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Disclosure to Promote the Right To Information
Whereas the Parliament of India has set out to provide a practical regime of right to
information for citizens to secure access to information under the control of public authorities,
in order to promote transparency and accountability in the working of every public authority,
and whereas the attached publication of the Bureau of Indian Standards is of particular interest
to the public, particularly disadvantaged communities and those engaged in the pursuit of
education and knowledge, the attached public safety standard is made available to promote the
timely dissemination of this information in an accurate manner to the public.
Mazdoor Kisan Shakti Sangathan
'The Right to Information, The Right to Live"
Jawaharlal Nehru
"Step Out From the Old to the New'
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National Building Code of India 2005, Bureau of Indian
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Satyanarayan Gangaram Pitroda
Invent a New India Using Knowledge
Bhartrhari — Nitisatakam
"Knowledge is such a treasure which cannot be stolen"
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Code of India 20JSS
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BUREAU OF INDIAN STANDARDS
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NATIONAL BUILDING CODE
OF INDIA 2005
NATIONAL
BUILDING
CODE OF INDIA
2005
BUREAU OF INDIAN STANDARDS
SP 7 : 2005
FIRST PUBLISHED 1970
FIRST REVISION 1983
SECOND REVISION 2005
© BUREAU OF INDIAN STANDARDS
ICS 0.120; 91.040.01
ISBN 81-7061-026-5
PRICE Rs. 7 550.00
PUBLISHED BY BUREAU OF INDIAN STANDARDS, MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR
MARG, NEW DELHI 110 002, PRINTED AT SUNSHINE PROCESS, C- 105/5, NARAINA INDUSTRIAL
AREA, PHASE I, NEW DELHI 1 10 028 (INDIA).
(iv)
FOREWORD
Construction programmes are interwoven in a large measure in all sectors of development, be it housing, transport,
industry, irrigation, power, agriculture, education or health. Construction, both public and private, accounts for
about fifty percent of the total outlay in any Five Year Plan. Half of the total money spent on construction
activities is spent on buildings for residential, industrial, commercial, administrative, education, medical, municipal
and entertainment uses. It is estimated that about half of the total outlay on buildings would be on housing. It is
imperative that for such a large national investment, optimum returns are assured and wastage in construction is
avoided.
Soon after the Third Plan, the Planning Commission decided that the whole gamut of operations involved in
construction, such as, administrative, organizational, financial and technical aspects, be studied in depth. For this
study, a Panel of Experts was appointed in 1965 by the Planning Commission and its recommendations are found
in the 'Report on Economies in Construction Costs' published in 1968.
One of the facets of building construction, namely, controlling and regulating buildings through municipal byelaws
and departmental handbooks received the attention of the Panel and a study of these regulatory practices revealed
that some of the prevailing methods of construction were outmoded; some designs were overburdened with
safety factors and there were other design criteria which, in the light of newer techniques and methodologies,
could be rationalized; and building byelaws and regulations of municipal bodies which largely regulate the
building activity in the country wherever they exist, were outdated. They did not cater to the use of new building
materials and the latest developments in building designs and construction techniques. It also became clear that
these codes and byelaws lacked uniformity and they were more often than not 'specification oriented' and not
'performance oriented*.
These studies resulted in a recommendation that a National Building Code be prepared to unify the building
regulations throughout the country for use by government departments, municipal bodies and other construction
agencies. The then Indian Standards Institution (now Bureau of Indian Standards) was entrusted by the Planning
Commission with the preparation of the National Building Code. For fulfilling this task a Guiding Committee for
the preparation of the Code was set up by the Civil Engineering Division Council of the Indian Standards Institution
in 1967. This Committee, in turn, set up 18 specialist panels to prepare the various parts of the Code. The
Guiding Committee and its panels were constituted with architects, planners, materials experts, structural,
construction, electrical illumination, air conditioning, acoustics and public health engineers and town planners.
These experts were drawn from the Central and State Governments, local bodies, professional institutions and
private agencies. The first version of the Code was published in 1970.
After the National Building Code of India was published in 1970, a vigorous implementation drive was launched
by the Indian Standards Institution to propagate the contents and use of the Code among all concerned in the field
of planning, designing and construction activities. For this, State-wise Implementation Conferences were organized
with the participation of the leading engineers, architects, town planners, administrators, building material
manufacturers, building and plumbing services installation agencies, contractors, etc.
These Conferences were useful in getting across the contents of the Code to the interests concerned. These
Conferences had also helped in the establishment of Action Committees to look into tfie actual implementation
work carried out by the construction departments, local bodies and other agencies in different States. The main
actions taken by the Action Committees were to revise and modernize their existing regulatory media, such as,
specifications, handbooks, manuals, etc, as well as building byelaws of local bodies like municipalities at city
and town levels, zilla parishads, panchayats and development authorities, so as to bring them in line with the
provisions contained in the National Building Code of India. In this process, the Indian Standards Institution
rendered considerable support in redrafting process.
Since the publication in 1970 version of the National Building Code of India, a large number of comments and
useful suggestions for modifications and additions to different parts and sections of the Code were received as a
result of use of the Code by all concerned, and revision work of building byelaws of some States. Based on the
comments and suggestion received the National Building Code of India 1970 was revised in 1983.
(v)
Some of the important changes in 1983 version included : addition of development control rules, requirements
for greenbelts and landscaping including norms for plantation of shrubs and trees, special requirements for low
income housing; fire safety regulations for high rise buildings; revision of structural design section based on new
and revised codes, such as Concrete Codes (plain and reinforced concrete and prestressed concrete), Earthquake
Code, Masonry Code; addition of outside design conditions for important cities in the country, requirements
relating to noise and vibration, air filter, automatic control, energy conservation for air conditioning; and guidance
on the design of water supply system for multi-storeyed buildings.
The National Building Code of India is a single document in which, like a network, the information contained in
various Indian Standards is woven into a pattern of continuity and cogency with the interdependent requirements
of Sections carefully analyzed and fitted in to make the whole document a cogent continuous volume. A continuous
thread of 'preplanning' is woven which, in itself, contributes considerably to the economies in construction
particularly in building and plumbing services.
The Code contains regulations which can be immediately adopted or enacted for use by various departments,
municipal administrations and public bodies. It lays down a set of minimum provisions designed to protect the
safety of the public with regard to structural sufficiency, fire hazards and health aspects of buildings; so long as
these basic requirements are met, the choice of materials and methods of design and construction is left to the
ingenuity of the building professionals. The Code also covers aspects of administrative regulations, development
control rules and general building requirements; fire protection requirements; stipulations regarding materials
and structural design; rules for design of electrical installations, lighting, air conditioning and lifts; regulation for
ventilation, acoustics and plumbing services, such as, water supply, drainage, sanitation and gas supply; measures
to ensure safety of workers and public during construction; and rules for erection of signs and outdoor display
structures.
Some other important points covered by the Code include 'industrialized systems of building' and 'architectural
control' . The increase in population in the years to come will have a serious impact on the housing problem. It
has been estimated that the urban population of India will continue to increase with such pace as to maintain the
pressure on demand of accommodation for them. Speed of construction is thus of an utmost importance and
special consideration has to be given to industrialized systems of building. With increased building activity, it is
also essential that there should be some architectural control in the development of our cities and towns if
creation of ugliness and slum-like conditions in our urban areas is to be avoided.
Since the publication of 1983 version of National Building Code of India, the construction industry has gone
through major technological advancement. In the last two decades, substantial expertise has been gained in the
areas of building planning, designing and construction. Also, lot of developments have taken places in the techno-
legal regime and techno-financial regime, apart from the enormous experience gained in dealing with natural
calamities like super cyclones and earthquakes faced by the country. Further, since the last revision in 1983
based on the changes effected in the Steel Code, Masonry Code and Loading Code as also in order to update the
fire protection requirements, three amendments were brought out to the 1983 version of the Code. Considering
these, it was decided to take up a comprehensive revision of the National Building Code of India.
The changes incorporated in the present Code, which is second revision of the Code, have been specified in the
Foreword to each Part/Section of the Code. Some of the important changes are:
a) A new Part 'Integrated Approach — Prerequisite for Applying the Provisions of the Code' emphasizing
on multi-disciplinary team approach for successfully accomplishing building/development project, has
been incorporated.
b) New chapters on significant areas like structural design using bamboo, mixed/composite construction
and landscaping have been added.
c) Number of provisions relating to reform in administration of the Code as also assigning duties and
responsibilities to all concerned professionals, have been incorporated/modified. Also detailed provisions/
performance to ensure structural sufficiency of buildings, have been prescribed so as to facilitate
implementation of the related requirements to help safely face the challenges during natural disasters
like earthquake.
d) Planning norms and requirements for hilly areas and rural habitat planning, apart from detailed planning
norms for large number of amenities have been incorporated.
e) Fire safety aspects have been distinctly categorized into fire prevention, life safety and fire protection
(vi)
giving detailed treatment to each based on current international developments and latest practices followed
in the country.
f) Aspects like energy conservation and sustainable development have been consistently dealt with in
various parts and sections through appropriate design, usage and practices with regard to building
materials, construction technologies and building and plumbing services. Renewable resources like
bamboo and practices like rain water harvesting have been given their due place.
g) The latest revised earthquake code, IS 1893 (Part 1) : 2002 'Criteria for earthquake resistant design of
structures: Part 1 General provisions and buildings', has been incorporated, due implementation of the
provisions of which in applicable seismic zone of the country, needs to be duly adhered to by the
Authorities.
The Code now published is the third version representing the present state of knowledge on various aspects of
building construction. The process of preparation of the 2005 version of the Code had thrown up a number of
problems; some of them were answered fully and some partially. Therefore, a continuous programme will go on
by which additional knowledge that is gained through technological evolution, users' views over a period of time
pinpointing areas of clarification and coverage and results of research in the field, would be incorporated in to
the Code from time to time to make it a living document. It is, therefore, proposed to bring out changes to the
Code periodically.
The provisions of this Code are intended to serve as a model for adoption by Public Works Departments and
other government construction departments, local bodies and other construction agencies. Existing PWD codes,
municipal byelaws and other regulatory media could either be replaced by the National Building Code of India
or suitably modified to cater to local requirements in accordance with the provisions of the Code. Any difficulties
encountered in adoption of the Code could be brought to the notice of the Sectional Committee for corrective
action.
(vii)
National Building Code Sectional Committee, CED 46
Chairman
Dr H. C. Visvesvaraya
'Chandrika\ at 15th Cross, 63-64 East Park Road
Malleswaram, Bangalore 560 003
Vice-chairman
SHRI V. SURESH
P-233/3, Officers Enclave,
Air Force Station, Rajokari, New Delhi 1 10 038
Organization
Ahmedabad Municipal Corporation, Ahmedabad
Bangalore Mahanagara Palike, Bangalore
Builders Association of India, Mumbai
Building Materials and Technology Promotion Council, New Delhi
Bureau of Energy Efficiency (Ministry of Power), New Delhi
Central Building Research Institute (CSIR), Roorkee
Central Public Health and Environmental Engineering Organisation
(Ministry of Urban Development and Poverty Alleviation),
New Delhi
Central Public Works Department (Central Designs Organization),
New Delhi
Central Public Works Department (Electrical Department),
New Delhi
Centre for Disaster Mitigation and Management, Anna University,
Chennai
Chennai Metropolitan Development Authority, Chennai
Construction Industry Development Council, New Delhi
Council of Architecture, New Delhi
Delhi Development Authority, New Delhi
Delhi Fire Service, Government of National Capital Territory
of Delhi, Delhi
Department of Science and Technology (Ministry of Science
and Technology), New Delhi
Directorate General of Employment and Training, New Delhi
Engineer-in-Chief s Branch, Army Headquarters, New Delhi
Forest Research Institute (Indian Council for Forestry Research
and Education), Dehra Dun
Housing and Urban Development Corporation Ltd, New Delhi
Indian Geotechnical Society, New Delhi
Representative(s)
Shri Vatsal S. Patel
Shri Jagdish A. Patel {Alternate)
Shri M. R. Sreenivasa Murthy
Shri R. Ramegowda {Alternate I)
Shri N. Krishna {Alternate II)
Shri B. G. Ahuja
Shri T. N. Gupta & Shri D. B. N. Rao
Representative
Shri V. K. Mathur
Shri B. S. Gupta {Alternate)
Shri B. B. Uppal
Shri V. K. Chaurasia {Alternate)
Chief Engineer (Designs)
Superintending Engineer (S & S) {Alternate)
Chief Engineer (Electrical) I
Director
Member Secretary
Shri N. V. Rakhunath {Alternate)
Shri P. R. Swarup
Shri Anil Chadha {Alternate)
Shri Premendra Raj Mehta
Shri Sudhir Vohra {Alternate)
Engineer Member
Chief Engineer (HQ) {Alternate)
Shri R. C. Sharma
Shri V. Rao Alyagari s--
Shri Ashwani Kumar
Brig S. K. Sharma
Shri D. K. Dinker {Alternate)
Director General
Director {Alternate)
Chairman & Managing Director
Shri R. K. Safaya {Alternate)
Shri D. B. Mahajan
Dr M. D. Desai {Alternate)
(viii)
Organization
Indian Institute of Technology (Centre for Energy Studies),
New Delhi
Indian Roads Congress, New Delhi
Institute of Town Planners, India, New Delhi
Institution of Fire Engineers (India), New Delhi
Ministry of Home Affairs, New Delhi
Ministry of Home Affairs (Disaster Management Division),
New Delhi
Ministry of Non-Conventional Energy Sources, New Delhi
Ministry of Road Transport and Highways, New Delhi
Municipal Corporation of Greater Mumbai, Mumbai
National Buildings Construction Corporation, New Delhi
National Council for Cement and Building Materials, Ballabgarh
National Design and Research Forum, The Institution of Engineers
(India), Bangalore
National Environmental Engineering Research Institute (CSIR),
Nagpur
North Eastern Council, Shillong
Public Works Department (Roads and Buildings), Gandhinagar
Research, Designs and Standards Organization (Ministry of Railways),
Lucknow
School of Planning and Architecture, New Delhi
Structural Engineering Research Centre (CSIR), Chennai
Suri and Suri Consulting Acoustical Engineers, New Delhi
The Energy and Resources Institute, New Delhi
The Indian Institute of Architects, New Delhi
The Institution of Engineers (India), Kolkata
The Institution of Surveyors, New Delhi
Town and Country Planning Organization, New Delhi
U.P. Housing and Development Board, Lucknow
Unitech Ltd, Gurgaon
In personal capacity (5, Sunder Nagar, New Delhi 110 003)
BIS Directorate General
Representative(s)
Prof N. K. Bansal
Chief Engineer (Design), CPWD
Superintending Engineer (Design), CPWD (Alternate)
dr s. k. kulshrestha
President
General Secretary (Alternate)
Fire Advisor
Shri M. P. Sajnani
Shri S. K. Swami (Alternate)
Dr T. C. Tripathi
Shri S. B. Basu
Shri P. Halder (Alternate)
Director (Engg Services & Projects)
City Engineer (Alternate)
Shri B. Prasad
Shri N. P. Agarwal (Alternate)
Shri Shiban Raina
Dr Anil Kumar (Alternate)
Prof R. Narayana Iyengar
Shri B. Suresh (Alternate)
Dr Arindam Ghosh
Dr V. P. Deshpande (Alternate)
Shri P. K. Deb
Shri V. P. Jamdar
Shri M. S. Jallundhwala (Alternate)
Shri R. K. Gupta
Shri J. P. Das (Alternate)
Director
Shri C. V. Vaidyanathan
Shri K. Mani (Alternate)
Shri Gautam Suri
Ms Mili Majumdar
Ms Vidisha Salunke-Palsule (Alternate)
Shri Balbir Verma
Shri Abhijit Ray (Alternate)
Prof G. P. Lal
Shri O. P. Goel (Alternate)
Shri K. S. Kharb
Shri R. K. Bhalla (Alternate)
Shri K. T. Gurumukhi
Shri J. B. Kshirsagar (Alternate)
Shri Hari Gopal
Shri Sushil Sharma
Shri Shahid Mahmood (Alternate)
Dr J. R. Bhalla
Shri S. K. Jain, Director & Head (Civil Engineering)
[Representing Director General (Ex-officio Member)]
Member Secretary
Shri Sanjay Pant
Joint Director (Civil Engineering)
(ix)
Special Panel for Guiding and Co-ordinating the
Revision of National Building Code of India, CED 46:SP
Organization
In personal capacity (P-233/3, Officers Enclave, Air Force Station,
Rajokari, New Delhi 110 038)
Building Materials and Technology Promotion Council, New Delhi
Central Building Research Institute (CSIR), Roorkee
Central Public Works Department, New Delhi
Council of Architecture, New Delhi
Engineer-in-Chief s Branch, Army Headquarters, New Delhi
The Institution of Engineers (India), Kolkata
Bureau of Indian Standards, New Delhi
Rep resenta tive( s )
Shri V. Suresh (Convener)
Shri T, N. Gupta
Shri V. K. Mathur
Shri H. S. Dogra
Shri Premendra Raj Mehta
Lt-Gen Hari Uniyal
Prof G. P. Lal
Shri O. P. Goel (Alternate)
Shri Sanjay Pant
Ad-hoc Group for Part of NBC, CED 46: AG
Organization
In personal capacity ('Chandrika', at 15th Cross, 63-64, East Park Road,
Malleswaram, Bangalore 560 003)
Council of Architecture, New Delhi
In personal capacity (P-233/3, Officers Enclave, Air Force Station,
Rajokari, New Delhi 110 038)
In personal capacity (A-39/B, DDA Flats, Munirka, New Delhi 110 067)
In personal capacity (EA-345, Maya Enclave, New Delhi 110 064)
Representative(s)
Dr H. C. Visvesvaraya (Convener)
Shri Premendra Raj Mehta
Shri V. Suresh
Shri P. B. Vuay
Shri J. N. Bhavani Prasad
Panel for Administration, Development Control Rules and
General Building Requirements, CED 46:P1
Organization
In personal capacity (P-233/3, Officers Enclave, Air Force Station,
Rajokari, New Delhi 110 038)
Ahmedabad Municipal Corporation, Ahmedabad
Building Materials and Technology Promotion Council, New Delhi
Central Building Research Institute (CSIR), Roorkee
Central Public Works Department, New Delhi
Consulting Engineers Association of India, New Delhi
Council of Architecture, New Delhi
Delhi Development Authority, New Delhi
Housing and Urban Development Corporation Ltd, New Delhi
Indian Association of Structural Engineers, New Delhi
Institute of Town Planners (India), New Delhi
Municipal Corporation of Delhi, Delhi
Municipal Corporation of Greater Mumbai, Mumbai
National Council for Cement and Building Materials, Ballabgarh
Representative(s)
Shri V. Suresh (Convener)
Representative
Shri T. N. Gupta
Shri Rajesh Malik (Alternate)
Shri V. K. Mathur
Shri N. K. Shangari (Alternate)
Shri R. S. Kaushal
Shri Sanjib Sengupta (Alternate)
Shri S. C. Mehrotra
Shri N. F. Patel (Alternate)
Shri Premendra Raj MjSHta
Shri Sudhjr Vohra (Alternate)
Shri R. C. Kinger
Shri A. K. Gupta (Alternate)
Shri K. C. Batra
Shri Mahendra Raj
Dr S. K. Kulshrestha
Engineer-in-Chief
Shri M. M. Das (Alternate)
Chief Engineer (Development Plan)
Deputy Chief Engineer (Development Plan)-I (Alternate)
Dr Anil Kumar
(x)
Organization
National Real Estate Development Council, New Delhi
School of Planning and Architecture, New Delhi
The Indian Institute of Architects, Mumbai
The Institution of Engineers (India), Kolkata
Town and Country Planning Organization, New Delhi
Representative(s)
Brig R. R. Singh (Retd)
Prof Subir Saha
Shri Balbir Verma
Shri Abhijit Ray {Alternate)
Shri A. D. Shirode
Shri P. B. Vuay {Alternate)
Shri J. B. Kshirsagar
Shri R. Srinivas {Alternate)
Panel for Fire Protection, CED 46:P2
Organization
In personal capacity {29/25, Old Rajendra Nagar, New Delhi 110 060)
Central Building Research Institute (CSIR), Roorkee
Central Public Works Department, New Delhi
Deolalikar Consultants Pvt Ltd, New Delhi
Directorate of Town and Country Planning, Government of Tamil Nadu,
Chennai
Engineer-in-Chief s Branch, Army Headquarters, New Delhi
Institution of Fire Engineers (India), New Delhi
Lloyd Insulations (India) Ltd, New Delhi
Ministry of Home Affairs, New Delhi
Delhi Fire Service, Government of National Capital Territory of Delhi,
Delhi
Municipal Corporation of Greater Mumbai (Mumbai Fire Brigade),
Mumbai
National Council for Cement and Building Materials, Ballabgarh
National Fire Service College (Ministry of Home Affairs), Nagpur
Oil Industry Safety Directorate, New Delhi
Regional Research Laboratory (CSIR), Jorhat
Spectral Services Consultants Pvt Ltd, New Delhi
Tariff Advisory Committee, Mumbai
The Institution of Engineers (India), Kolkata
In personal capacity {P-233/3, Officers Enclave, Air Force Station,
Rajokari, New Delhi 110 038)
Representative(s)
Shri S. K. Dheri {Convener)
Dr T. P. Sharma
Dr Gopal Krishna {Alternate)
Shri Arvind Kansal
Shri R. S. Kaushal {Alternate)
Shri S. G. Deolalikar
Shri S. Dhanasekaran
Shri R. Rajagopalan {Alternate)
Shri R. A. Dubey
Shri Ajay Shankar {Alternate)
Shri U. S. Chhillar
Shri S. P. Batra {Alternate)
Shri Sanjeev Angra
Shri K. K. Mitra {Alternate)
Shri Om Prakash
Shri D. K. Shammi {Alternate)
Shri R. C. Sharma
Shri G. C. Misra {Alternate)
Shri A. D. Jhandwal
Shri V. H. Naik {Alternate)
Dr Anil Kumar
Dr K. C. Wadhwa
Shri Shamim {Alternate)
Shri D. Jagannath
Shri S. K. Aggarwal {Alternate)
Representative
Shri Sandeep Goel
Shri Z. U. Islam
Shri D. N. Saha {Alternate)
Prof M. P. Chowdiah
Shri K. B. Rajoria {Alternate)
Shri V. Suresh
Panel for Building Materials, CED 46:P3
Organization
Building Materials and Technology Promotion Councils, New Delhi
Central Building Research Institute (CSIR), Roorkee
Central Public Works Department, New Delhi
Representative(s)
Shri T. N. Gupta {Convener)
Dr C. L. Verma
Shri L. K. Agarwal {Alternate)
Shri H. K. L. Mehta
Shri R. C. Gupta {Alternate)
(xi)
Organization
Council of Architecture, New Delhi
Department of Science and Technology (Ministry of Science and
Technology), New Delhi
Engineer-in-Chief s Branch, Army Headquarters, New Delhi
Housing and Urban Development Corporation Ltd, New Delhi
Indian Plywood Industries Research and Training Institute,
Bangalore
National Council for Cement and Building Materials, Ballabgarh
The Institution of Engineers (India), Kolkata
Representative(s)
Shri Anurag Roy
Shri Atul Gupta (Alternate)
Shri Soumitra Biswas
Shri G. Srikanth (Alternate)
Shri A. K. Singh
Shri P. K. Gupta (Alternate)
Chairman and Managing Director
Shri S. K. Taneja (Alternate)
Shri K. Shyamasundar
Shri M. Pawan Kumar (Alternate)
Shri Shiban Raina
Dr K. Mohan (Alternate)
Shri G. L. Rao
Shri R. S. Goel (Alternate)
Panel for Loads, Forces and Effects, CED 46:P4
Organization
National Council for Cement and Building Materials, Ballabgarh
Building Materials and Technology Promotion Council, New Delhi
Central Building Research Institute, Roorkee
Central Public Works Department, New Delhi
Centre for Disaster Mitigation and Management, Anna University,
Chennai
Mahendra Raj Consultants Pvt Ltd, New Delhi
Structural Engineering Research Centre (CSIR), Chennai
The Institution of Engineers (India), Kolkata
In personal capacity (Professor of Bridge Engineering, Railway Chair,
Department of Civil Engineering, Indian Institute of Technology,
Roorkee 247 667)
In personal capacity (Emeritus Scientist, Structural Engineering
Research Centre, Madras CSIR Campus, Taramani,
Chennai 600 113)
In personal capacity (P-233/3, Officers Enclave, Air Force Station,
Rajokari, New Delhi 110 038)
Representative(s)
Dr Anil Kumar (Convener)
Shri T. N. Gupta
Shri I. S. Sidhu (Alternate)
Shri B. S. Gupta
Shri A. K. MrrTAL (Alternate)
Shri N. M. D. Jain
Shri Abhay Sinha (Alternate)
Dr R. K. Bhandari
Shri Mahendra Raj
Shri J. Ghose (Alternate)
Shri C. V. Vaidyanathan
Shri K. Mani (Alternate)
Shri P. P. Dharwadkar
Dr Prem Krishna
Dr T. V. S. R. Appa Rao
Shri V. Suresh
Panel for Soils and Foundations, CED 46:P5
Organization
Centre for Disaster Mitigation and Management, Anna University,
Chennai
Central Building Research Institute (CSIR), Roorkee
Afcons Infrastructure Limited, Mumbai
Central Public Works Department, New Delhi
Delhi Development Authority, New Delhi
Representative(s)
Dr R. K. Bhandari (Convener before 19 September 2003)
Shri Chandra Prakash (Convener since 19 September 2003)
Dr Surendra Kumar (Alternate)
Shri S. B. Joshi
Shri D. G. Bhagwat (Alternate)
Shri Bhagwan Singh
Shri R. K. Singhal (Alternate)
Shri S. P. Rustogi
Shri J. M. Joshi (Alternate)
(xii)
Organization
Engineer-in-Chief s Branch, Army Headquarters, New Delhi
Indian Geotechnical Society, New Delhi
National Council for Cement and Building Materials, Ballabgarh
The Institution of Engineers (India), Kolkata
Representative(s)
Col R. N. Malhotra
Col N. B. Saxena (Alternate)
Maj Gen S. N. Mukerjee
Shri Sanjay Gupta (Alternate)
Dr Anil Kumar
Shri H. K. Julka (Alternate)
Prof Janardan Jha
Panel for Timber, CED 46:P6
Organization
In personal capacity (Pratap Nursery Lane, Near Gurdwara,
Panditwari, Dehra Dun 248007)
Bamboo Society of India, Bangalore
Building Materials and Technology Promotion Council, New Delhi
Central Building Research Institute (CSIR), Roorkee
Central Public Works Department, New Delhi
Engineer-in-Chief's Branch, Army Headquarters, New Delhi
Forest Research Institute (Indian Council for Forestry Research
and Education), Dehra Dun
Housing and Urban Development Corporation Ltd, New Delhi
Indian Plywood Industries Research and Training Institute,
Bangalore
North Eastern Council, Shillong
The Institution of Engineers (India), Kolkata
In personal capacity [No. 179 (710), 24th B-Cross, 3rd Block,
Jayanagar, Bangalore 560 Oil]
In personal capacity (103/H, Vasant Vihar, P. 0. New Forest,
Dehra Dun 248 006)
Representative(s)
Shri K. S. Pruthi (Convener)
Shri A. C. Lakshmanan
Dr K. A. Kushalappa (Alternate)
Shri T. N. Gupta
Shri Rajesh Malik (Alternate)
Shri S. K. Mittal
Shri B. S. Rawat (Alternate)
Shrimati P. Verma
Shri G. C. Khattar (Alternate)
Shri A. K. Singh
Shri P. K. Gupta (Alternate)
Shri B. K. Bhatia
Chairman and Managing Director
Shri S. K. Taneja (Alternate)
Shri K. Shyamasundar
Shri H. Guruva Reddy (Alternate)
Shri P. K. Deb
Shri Krishna Kumar
Dr H. N. Jagadeesh
Shri S. S, Rajput
Panel for Masonry, CED 46:P7
Organization
Delhi Tourism and Transportation Development Corporation,
New Delhi
Building Materials and Technology Promotion Council, New Delhi
Central Building Research Institute (CSIR), Roorkee
Central Public Works Department, New Delhi
Delhi Development Authority, New Delhi
Engineer-in-Chief's Branch, Army Headquarters, New Delhi
Indian Institute of Science (Centre for Astra), Bangalore
Representative(s)
Shri Jose Kurian (Convener)
Shri T. N. Gupta
Shri Pankaj Gupta (Alternate)
Shri A. K. Mittal
Shri Shailesh Kumar (Alternate)
Dr A. K. Mittal
Shri Neeraj Mishra (Alternate I)
Shri A. K. Jha (Alternate II)
Shri S. P. Rustogi
Shri J. M. Joshi (Alternate)
Shri D. R. Kurdiya
Shri Subodh Kumar (Alternate)
Dr B. V. Venkatarama Reddy
Dr K. S. Nanjunda Rao (Alternate)
(xiii)
Organization
Indian Institute of Technology, Kanpur
Indian Institute of Technology, New Delhi
Public Works Department, Government of Maharashtra, Mumbai
Structural Engineering Research Centre (CSIR), Chennai
The Institution of Engineers (India), Kolkata
Representative(s)
Dr Durgesh C. Rai
Dr C. V. R. Murty {Alternate I)
Dr Sudhir K. Jain {Alternate II)
Dr S. N. Sinha
Shri P. K. Ninave
Shri R. Jayaraman
Shri A. Chellappan {Alternate)
Shri S. L. Garg
Panel for Plain, Reinforced and Prestressed Concrete, CED 46:P8
Organization
In personal capacity {35, Park Avenue, Annamma, Naicker Street,
Kuniamuthur, Coimbatore 641 008)
Central Building Research Institute (CSIR), Roorkee
Central Public Works Department, New Delhi
Delhi Tourism and Transportation Development Corporation,
New Delhi
Gammon India Ltd, Mumbai
Hindustan Prefab Limited, New Delhi
Larsen and Toubro Ltd, ECC Construction Group, Chennai
Ministry of Road Transport and Highways, New Delhi
National Council for Cement and Building Materials, Ballabgarh
Research, Designs and Standards Organization (Ministry of Railways),
Lucknow
Structural Engineering Research Centre (CSIR), Chennai
Tandon Consultants, New Delhi
The Institution of Engineers (India), Kolkata
Representative(s)
Dr C. Rajkumar {Convener)
Dr B. S. Gupta
Dr B. K. Rao {Alternate I)
Dr Awadesh Kumar {Alternate II)
Shri N. M. D. Jain
Shri Abhay Sinha {Alternate)
Shri Jose Kurian
Shri S. A. Reddi
Shri Hazari Lal
Shri M. Kundu {Alternate)
Shri K. P. Raghavan
Shri S. Kanappan {Alternate)
Shri T. B. Banerjee
Shri Satish Kumar {Alternate)
Dr Anil Kumar
Shri H. K. Julka {Alternate)
Shri R. K. Gupta
Shri J. P. Das {Alternate I)
Shri A. K. Gupta {Alternate H)
Dr N. Lakshmanan
Shri H. G. Sreenath {Alternate)
Shri Mahesh Tandon
Shri S. S. Chakrabarty
Organization
MECON Ltd, Ranchi
Central Public Works Department, New Delhi
Panel for Steel, CED 46:P9
Representa tive(s)
Shri A. Basu {Convener)
Chief Engineer
Engineer-in-Chief s Branch, Army Headquarters, New Delhi
Indian Institute of Technology, Chennai
Institute for Steel Development and Growth, Kolkata
Kalpataru Power Transmission Ltd, Gandhinagar
M. N. Dastur and Co Ltd, Kolkota
Suprintending Engineer (P & A) {Alternate)
Shri D. K. Dinker
Col V. K. Tyagi {Alternate)
Dr V. Kalyanaraman
Dr T. K. Bandyopadhyay
Shri Ardit Guha {Alternate I)
Shri P. L. Rao {Alternate II)
Shri M. C. Mehta
Shri B. K. Satish {Alternate)
Shri Satyaki Sen
Shri Tapan Kumar Bhaumik {Alternate)
(xiv)
Organization
Research, Designs and Standards Organization (Ministry of Railways),
Lucknow
SPECO Engineering Pvt Ltd, New Delhi
Structural Engineering Research Centre (CSIR), Chennai
The Institute of Engineers (India), Kolkata
Representative(s)
Shri R. K. Gupta
Shri D. K. Singh (Alternate)
Shri Onkar Singh
Dr S. Seetharaman
Shri S. Arul Jayachandran {Alternate)
Shri R. P. Gupta
Panel for Prefabrication and Systems Buildings, CED46:P10
Organization
Larsen and Toubro Ltd, Chennai
B. G. Shrike Construction Technology Pvt Ltd, Pune
Central Building Research Institute (CSIR), Roorkee
Central Public Works Department, New Delhi
Engineer-in-Chief's Branch, Army Headquarters, New Delhi
Hindustan Prefab Limited, New Delhi
Institute for Steel Development and Growth, Kolkata
Lloyd Insulations (India) Ltd, New Delhi
National Council for Cement and Building Materials, Ballabgarh
Shirish Patel and Associates Consultants Pvt Ltd, Mumbai
Structural Engineering Research Centre (CSIR), Chennai
System Building Technologists, New Delhi
The Indian Institute of Architects, Mumbai
The Institution of Engineers (India), Kolkata
Representative(s)
Shri A. Ramakrishna (Convener)
Shri K. V. Rangaswami (Alternate)
Shri G. R. Bharitkar
Shri R. P. Jakhalekar (Alternate)
Shri B. N. Hira
Shri D. K. Gautam (Alternate)
Chief Engineer (NDZ-III)
Shri A. K. Garg (Alternate)
Col R. N. Malhotra
Shri P. K. Gupta (Alternate)
Shri Hazari Lal
Shri M. Kundu (Alternate)
Dr T. K. Bandyopadhyay
Shri Alok Baishya (Alternate)
Shri Mohit Khanna
Shri K. K. Mitra (Alternate)
Shri H. K, Julka
Shri Satish Sharma (Alternate)
Shri Shirish B. Patel
Shri P. H. Srinivasachar (Alternate)
Shri H. G, Sreenath
Shri R. Jayaraman (Alternate)
Shri G. B. Singh
Shri S. R. Sikka
Dr R. K. Bhandari
Shri P. B. Vuay (Alternate)
Panel for Constructional Practices and Safety, CED 46:P11
Organization
In personal capacity (103, Charak Sadan, Vikaspuri,
New Delhi 110 018)
Adlakha and Associates, New Delhi
Builders Association of India, Mumbai
Central Building Research Institute (CSIR), Roorkee
Central Public Works Department, New Delhi
Construction Industries Development Council, New Delhi
Director General of Factory Advice Service and Labour Institute
(Ministry of Labour), Mumbai
Representative(s)
Shri P. Krishnan (Convener)
Shri Pramod Adlakha
Shri Raj Pal Arora
Shri N. K. Shangari
Shri B. S. Gupta (Alternate)
Shri R. P. Bhardwaj
Shri P. R. Swarup
Shri Sunil Mahajan (Alternate)
Shri S. K. Dutta
Shri I. Roychowdhuri (Alternate)
(XV)
Organization
Engineer-in-Chief s Branch, Army Headquarters, New Delhi
Engineers India Limited, New Delhi
Gammon India Ltd, Mumbai
Indian Plywood Industries Research and Training Institute,
Bangalore
Larsen and Toubro Ltd, Chennai
National Building Construction Corporation, New Delhi
School of Planning and Architecture, New Delhi
The Indian Institute of Architects, Mumbai
The Institution of Engineers (India), Kolkata
Representative(s)
Shri Dinesh Sikand
Shri A. K. Singh {Alternate)
Shri M. P. Jain
Shri A. K. Tandon {Alternate)
Shri K. N. Chatterjee
Shri S. C. Sarin {Alternate)
Shri H. Guruva Reddy
Shri M. Pa van Kumar {Alternate)
Shri R. P. Sakunia
Shri B. Prasad
Shri N. P. Agarwal {Alternate)
Dr V. Thiruvengadam
Shri Kailash Chandra Jaitia
Shri C. M. Sapra {Alternate)
Shri H. P. Jamdar
Shri K. B. Rajoria {Alternate)
Panel for Lighting and Ventilation, CED 46:P12
Organization
Central Building Research Institute (CSIR), Roorkee
All India Institute of Hygiene and Public Health, Kolkata
Bureau of Energy Efficiency (Ministry of Power), New Delhi
Central Public Works Department, New Delhi
Council of Architecture, New Delhi
Director General Factory Advice Service and Labour Institute
(Ministry of Labour), Mumbai
Engineer-in-Chief s Branch, Army Headquarters, New Delhi
Indian Society for Lighting Engineers, New Delhi
Ministry of Non-Conventional Energy Sources, New Delhi
Municipal Corporation of Greater Mumbai, Mumbai
National Physical Laboratory (CSIR), New Delhi
Philips India Ltd, Mumbai
School of Planning and Architecture, New Delhi
The Indian Institute of Architects, Mumbai
The Institution of Engineers (India), Kolkata
Representative(s)
Shri V. K. Mathur {Convener)
Dr Ishwar Chand {Alternate I)
Shri Shree Kumar {Alternate II)
Dr Gautam Banerjee
Representative
Chief Engineer (E) II
Superintending Engineer (E) P {Alternate)
Prof Vinod Kumar Gupta
Shri S. K. Dutta
Shri I. Roychowdhuri {Alternate)
Shri S. K. Maheshwari
Shri A. C. Verma {Alternate)
Shri P. K. Bandyopadhyay
Shri Bibek Bandyopadhyay
Shri P. G. Chavan
Shri R. K. Rahate {Alternate)
Dr H. C. Kandpal
Shrimati Sudeshna Mukhopadhyay
Shri S. P. Tambe {Alternate)
Prof Arvind Kishan
Prof Ashok B. Lall
Prof C S. Jha
Panel for Electrical Installations, CED 46:P13
Organization
In personal capacity {EA 345, Maya Enclave, New Delhi 1 10 064)
Bureau of Energy Efficiency (Ministry of Power), New Delhi
Central Electricity Authority, New Delhi
Chief Electrical Inspectorate, Tamil Nadu
Representative(s)
Shri J. N. Bhavani Prasad {Convener)
Representative
Chief Engineer (DP & D)
Director (UT) {Alternate)
Shri S. Subramanian
Shri M. Kamal Batcha {Alternate)
(xvi)
Organization
Engineer-in-Chief s Branch, Army Headquarters, New Delhi
Engineers India Ltd, New Delhi
Fairwood Consultants Pvt Ltd, New Delhi
Siemens Ltd, Chennai
The Institution of Engineers (India), Kolkata
Representative(s)
Shri Ajay Shankar
Shri Shiv Om Prakash {Alternate)
Shri A. Ananthanarayan
Shri N. Sethi {Alternate) •
Smt Shruti Goel
Shri Hemant Tungare
Shri Ajit Deshpande {Alternate)
Prof Samiran Choudhary
Lt Gen S. K. Jain {Alternate)
Panel for Air Conditioning and Heating, CED 46:P14
Organization
Spectral Services Consultants Pvt Ltd, New Delhi
Airtron Consultants, Bangalore
Air Treatment Engineering Pvt Ltd, Chennai
Blue Star Limited, Mumbai
Bureau of Energy Efficiency (Ministry of Power), New Delhi
Central Building Research Institute (CSIR), Roorkee
Central Public Works Department, New Delhi
Engineer-in-Chief s Branch, Army Headquarters, New Delhi
Hi-Tech Consultant, New Delhi
Indian Institute of Technology, New Delhi
Indian Society for Heating, Refrigeration and Air-Conditioning
Engineers, New Delhi
Sterling India Consulting Engineers, New Delhi
Suvidha Engineers India Ltd, Noida
The Institution of Engineer (India), Kolkata
Voltas Limited, New Delhi
In personal capacity (K-43, Kailash Colony, New Delhi 110 048)
Representative(s)
Dr Prem C. Jain {Convener)
Shri Ashish Rakheja {Alternate)
Shri R. V. Simha
Shri K. P. S. Ramesh
Shri Jitendra Moreshwar Bhambure
Representative
Dr Ishwar Chand
Shri B. M Suman {Alternate)
Shri S. R. Subramanian
Shri S. P. Baranwal {Alternate)
Shri Narendra Kumar
Shri R. A. Dubey {Alternate)
Shri N. S. Hukmani
Dr R. S. Agarwal
Shri N. S. Hukmani
Shri G. C. Modgil
Shri Alok C, Tandon
Shri Pradeep Chaturvedi
Shri S. M. Kulkarni
Shri Atul Malik {Alternate)
Shri M. M. Pande
Panel for Acoustics, Sound Insulation and Noise Control, CED 46:P15
Organization
Suri and Suri Consulting Acoustical Engineers, New Delhi
All India Radio, New Delhi
Central Building Research Institute (CSIR), Roorkee
Central Public Works Department, New Delhi
Engineer-in-Chief s Branch, Army Headquarters, New Delhi
Indian Institute of Science, Bangalore
Indian Institute of Technology, Chennai
Indian Institute of Technology, Kharagpur
Representati ve ( s )
Shri Gautam Suri {Convener)
Shri Deepak Mehrotra
Shri S. Muthuswamy (Alternate)
Shri R. K. Srivastava
Shri R. L. Dhabal {Alternate)
Shri K. A. Ananthanarayanan
Shri N. Nagarajan {Alternate)
Brig S. K. Sharma
Shrimati Anuradha Bhasin (Alternate)
Prof M. L. Munjal
Prof S. Naryanan
Dr A. Ramachandraiah (Alternate)
Dr A. R. Mohanty
( xvii )
Organization
Lloyd Insulations (India) Pvt Ltd, New Delhi
National Physical Laboratory (CSIR), New Delhi
School of Planning and Architecture, New Delhi
The Indian Institute of Architects, Mumbai
The Institution of Engineers (India), Kolkata
Representative(s)
Shri N. Srinivas
Shri B. S. Jamwal (Alternate)
Dr V. Mohanan
Dr Omkar Sharma (Alternate)
Prof (Dr) Shovan K. Saha
Shri Indranath Basu
Shri K. V. Chaubal
Shri P. K. Adlakha (Alternate)
Panel for Installation of Lifts and Escalators, CED 46:P16
Organization
KONE Elevators India Ltd
Central Public Works Department, New Delhi
Chief Electrical Inspectorate, Government of Delhi, New Delhi
Chief Electrical Inspectorate, Govt of Tamil Nadu, Chennai
Delhi Development Authority, New Delhi
ECE Industries Ltd, Ghaziabad
Engineer-in-Chief's Branch, Army Headquarters, New Delhi
Otis Elevator Company (India) Ltd, New Delhi
Public Works Department, Government of Maharashtra, Mumbai
Schindler India Pvt Ltd, Mumbai
The Institution of Engineers (India), Kolkata
In personal capacity [4, Vidharbha Samrat Co-operative Housing
Society, 93 C, V. P. Road, Vile Parle (West), Mumbai 400 056]
Representative(s)
Shri A. Sankarakrishnan (Convener)
Shri L. N. Venkatraman (Alternate I)
Shri S. Emanuel Rajasekaran (Alternate II)
Shri J. K. Chaudhury
Shri A. S. Luthra (Alternate)
Shri K. L. Grover
Shri A. K. Aggarwal (Alternate)
Shri S. Subramanian
Shri M. Kamal Batcha (Alternate)
Shri S. K. Sinha
Shri N. K. Gupta (Alternate)
Shri P. K. Banka
Shri Jagat Mohan (Alternate)
Shri Rama Nath
Shri M. L. Bansal (Alternate)
Shri V. S. Mohan
Shri S. P. Rao (Alternalte I)
Shri Anurag Manglk (Alternate II)
Shri A. M. Thatte
Shri S. D. Mahajan (Alternate)
Shri Ronnie Dante
Shri T. A. K. Mathews (Alternate)
Shri Jagman Singh
Dr R. K. Dave (Alternate)
Shri A. S. Herwadkar
Panel for Plumbing Services, CED 46:P17
Organization
Deolalikar Consultants Pvt Ltd, New Delhi
Birhan Mumbai Licenced Plumbers Association, Mumbai
Central Building Research Institute (CSIR), Roorkee
Central Ground Water Board, New Delhi
Central Pollution Control Board, New Delhi
Central Public Works Department, New Delhi
Delhi Development Authority, New Delhi
Representative(s)
Shri S. G. Deolalikar (Convener)
President ^
Shri H. Gfl Gandhi (Alternate)
Shri Suresh Kumar Sharma
Shri Ajay Singh (Alternate I)
Shri R. S. Chimote (Alternate II)
Dr Saleem Romani
Shri S. K. Sharma (Alternate)
Dr A. B. Akolkar
Dr M. Sundarevadival (Alternate)
Shri H. S. Dogra
Shri A. K. Sinha (Alternate)
Shri S. P. Rustogi
Shri G. K. Sethi (Alternate)
( xviii )
Organization
Delhi Jal Board, New Delhi
Engineer- in-Chief s Branch, Army Headquarters, New Delhi
Indian Plumbing Association, New Delhi
Indraprastha Gas Ltd, New Delhi
Municipal Corporation of Delhi, Delhi
Municipal Corporation of Greater Mumbai, Mumbai
National Environmental Engineering Research Institute (CSIR),
Nagpur
Spectral Services Consultants Pvt Ltd, New Delhi
The Indian Institute of Architects, Mumbai
The Institution of Engineers (India), Kolkata
In personal capacity (B/58A, Gangotri Enclave, Alaknanda,
New Delhi 110 019)
In personal capacity (Principal Advisor, School of Environment
Management, Guru Gobind Singh Indraprastha University,
Keshmere Gate, Delhi 110 006)
In personal capacity (610, Technology Apartments, 24, Patparganj,
Delhi 110 092)
Representative(s)
Shri Subhash Chander
Shri Jitendra Singh
Shri Surya Prakash {Alternate)
Shri Sudhakaran Nair
Shri P. Ramachandran (Alternate)
Shri Peeyush Tripathi
Shri C. S. Sagar (Alternate)
Engineer-in-Chief
Shri M. M. Das (Alternate)
Shri T. V. Shah
Shri V. R. Pedhnekar (Alternate)
Dr Apurba Gupta
Shri P. S. Kelkar (Alternate)
Shri Sandeep Goel
Shri Uday Pande
Shri P. C. Tyagi
Shri J. D' Cruz
Dr D. K. Chadha
Shri Subir Paul
Panel for Landscaping, Signs and Outdoor
Organization
In personal capacity (5, Sunder Nagar, New Delhi 110003)
Central Public Works Department, New Delhi
Council of Architecture, New Delhi
Delhi Urban Arts Commission, New Delhi
Housing and Urban Development Corporation, New Delhi
Institute of Town Planners, India, New Delhi
Municipal Corporation of Delhi, Delhi
Municipal Corporation of Greater Mumbai, Mumbai
National Institute of Design, Ahmedabad
Selvel Publicity and Consultants Pvt Ltd, Mumbai
Shaheer Associates, New Delhi
Town and Country Planning Organization, New Delhi
The Indian Institute of Architects, Mumbai
The Institution of Engineers (India), Kolkata
In personal capacity (D-198, Defence Colony, New Delhi 110024)
Display Structures, CED 46:P18
Representative(s)
Dr J, R. Bhalla (Convener)
Shri Arvind Kansal
Shri A. N. Devikar (Alternate)
Kumari Vinita C. K. Vijayan
Shri H. K. Yadav
Shri Dina Nath (Alternate)
Shri R. K. Safaya
Dr S. K. Kulshrestha
Shri S. S. Hadke
Shri S. Ramesh (Alternate)
Shri M. S. Ghag
Shri R. K. Rahate (Alternate)
Shri Anando Dutta
Shri J. G. Sevak (Alternate)
Shri K. S. Nicholson
Prof M. Shaheer
Shri J. B. Kshirsagar
Shri Y. Ramesh (Alternate)
Shri Mahesh Paliwal
Prof Jitendra Singh
Shri Ravindra Bhan
Member Secretary
Shri Sanjay Pant
Joint Director (Civil Engineering)
Joint Member Secretary
Shri S. K. Verma
Deputy Director (Civil Engineering)
(xix)
Important Explanatory Note for Users of Code
In this Code, where reference is made to 'accepted standards' in relation to
material specification, testing or other related information or where reference
is made to 'good practice' in relation to design, constructional procedures or
other related information, the Indian Standards listed at the end of the
concerned Parts/Sections may be used to the interpretation of these terms.
At the time of publication, the editions indicated in the above Indian Standards
were valid. All standards are subject to revision and parties to agreements
based on the Parts/Sections are encouraged to investigate the possibility of
applying the most recent editions of the standards.
In the list of standards given at the end of each Part/Section, the number
appearing in the first column indicates the number of the reference in that
Part/Section. For example:
a) accepted standard [3(1)] refers to the standard given at serial number
1 of the list of standards given at the end of Part 3, that is IS 8888
(Part 1) : 1993 'Guide for requirements of low income housing:
Part 1 Urban area (first revision)' .
b) good practice [6-5 A(22)] refers to the standard given at serial number
22 of the list of standards given at the end of sub-section 5 A of Part 6,
that is IS 4926 : 2003 'Code of practice for ready-mixed concrete
(second revision) 9 .
c) accepted standard 7(9) refers to the standard given at serial number 9
of the list of standards given at the end of Part 7, that is IS 2925 : 1984
'Specification for industrial safety helmets (second revision)'.
d) accepted standard [8-5(4)] refers to the standard given at serial number
2 of the list of standards given at the end of Section 5 of Part 8, that
is IS 14665 (Part 3/Sec 1 and 2) : 2000 'Electric traction lifts: Part 3
Safety rules, Section 1 Passenger and goods lifts, Section 2 Service
lifts'.
e) good practice [9-2(3)] refers to the standard given at serial number 3
of the list of standards given at the end of Section % of Part 9, that
is IS 8198 (Part 5) : 1984 'Code of practice for steel cylinders for
compressed gases: Part 5 Liquefied petroleum gas (LPG) (first
revision)'. /
(xxi)
INFORMATION FOR THE USERS
For the convenience of the users, this publication is also available in the following five groups of the National
Building Code of India 2005 each incorporating the related Parts/Sections dealing with particular area of building
activity:
Group 1
For Development, Building
Planning and Related
Aspects
Group 2
For Structural Design and
Related Aspects
PartO:
Part 2.
Part 4
Part 5
Part 10
PartO:
Part 6:
Group 3 For Construction Related
Aspects including Safety
Group 4 For Aspects Relating to
Building Services
PartO:
Part 7:
PartO:
Part 8:
Group 5 For Aspects Relating to
Plumbing Services
including Solid Waste
Management
PartO:
Part 9:
Integrated Approach — Prerequisite for Applying
Provisions of the Code
Administration Part 3: Development Control Rules
Fire and Life Safety and General Building Requirements
Building Materials
Landscaping, Signs and Outdoor Display Structures
Section 1 Landscape Planning and Design
Section 2 Signs and Outdoor Display Structures
Integrated Approach — Prerequisite for Applying
Provisions of the Code
Structural Design
Section 1 Loads, Forces and Effects
Section 2 Soils and Foundations
Section 3 Timber and Bamboo
3A Timber
3B Bamboo
Section 4 Masonry
Section 5 Concrete
5 A Plain and Reinforced Concrete
5B Prestressed Concrete
Section 6 Steel
Section 7 Prefabrication, Systems Building and
Mixed/Composite Construction
7A Prefabricated Concrete
7B Systems Building and Mixed/
Composite Construction
Integrated Approach — Prerequisite for Applying
Provisions of the Code
Constructional Practices and Safety
Integrated Approach — Prerequisite for Applying
Provisions of the Code
Building Services
Section 1 Lighting and Ventilation
Section 2 Electrical and Allied Installations
Section 3 Air conditioning, Heating and Mechanical
Ventilation
Section 4 Acoustics, Sound Insulation and Noise
Control
Section 5 Installation of Lifts and Escalators
Integrated Approach — Prerequisite for Applying
Provisions of the Code
Plumbing Services
Section 1 Water Supply, Drainage and Sanitation
(including Solid Waste Management)
Section 2 Gas Supply
The information contained in different groups will essentially serve the concerned professionals dealing in the
respective areas.
( xxii )
CONTENTS
Total Pages
Part Integrated Approach — Prerequisite for Applying Provisions of the Code ... 12
Part 1 Definitions ••• 16
Part 2 Administration * * • 24
Part 3 Development Control Rules and General Building Requirements ... 64
Part 4 Fire and Life Safety • • • 88
Part 5 Building Materials • • • 40
Part 6 Structural Design
Section 1 Loads, Forces and Effects ... 104
Section 2 Soils and Foundations • • • 48
Section 3 Timber and Bamboo
3A Timber ... 50
3B Bamboo ... 24
Section 4 Masonry • • * 44
Section 5 Concrete
5 A Plain and Reinforced Concrete ... 90
5B Prestressed Concrete ... 6
Section 6 Steel ... 8
Section 7 Prefabrication, Systems Building and Mixed/Composite
Construction
7 A Prefabricated Concrete ... 22
7B Systems Building and Mixed/Composite Construction ... 12
Part 7 Constructional Practices and Safety ... 70
Part 8 Building Services
Section 1 Lighting and Ventilation ... 48
Section 2 Electrical and Allied Installations ... 68
Section 3 Air Conditioning, Heating and Mechanical Ventilation ... 48
Section 4 Acoustics, Sound Insulation and Noise Control ... 44
Section 5 Installation of Lifts and Escalators ... 42
Part 9 Plumbing Services
Section 1 Water Supply, Drainage and Sanitation (including Solid ... 90
Waste Management)
Section 2 Gas Supply - • • 14
Part 10 Landscaping, Signs and Outdoor Display Structures
Section 1 Landscape Planning and Design ... 30
Section 2 Signs and Outdoor Display Structures ... 24
( xxiii )
NATIONAL BUILDING CODE OF INDIA
PART INTEGRATED APPROACH — PREREQUISITE FOR
APPLYING PROVISIONS OF THE CODE
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 GENERAL
4 TEAM APPROACH
5 PLANNING, DESIGNING AND DEVELOPMENT
6 CONSTRUCTION/EXECUTION (ACTUALIZATION)
7 OPERATION AND MAINTENANCE
ANNEX A BRIEF DETAILS OF THE COVERAGE OF VARIOUS PROVISIONS
UNDER DIFFERENT OTHER PARTS/SECTIONS OF THIS CODE
5
5
5
5
6
7
8
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
In order to provide safe and healthy habitat, careful consideration needs to be paid to the building construction
activity. Building planning, designing and construction activities have developed over the centuries. Large number
of ancient monuments and historical buildings all over the world bear testimony to the growth of civilization
from the prehistoric era with the extensive use of manual labour and simple systems as appropriate to those ages
to the present day mechanized and electronically controlled operations for designing and constructing buildings
and for operating and maintaining systems and services. In those days those buildings were conceptualized and
built by master builders with high levels of artisan skills. Technological and socio-economic developments in
recent times have led to remarkable increase in demand for more and more sophistication in buildings resulting
in ever increasing complexities. These perforce demand high levels of inputs from professionals of different
disciplines such as architecture, civil engineering, structural engineering, functional and life safety services
including special aspects relating to utilities, landscaping, etc in conceptualization, spatial planning, design and
construction of buildings of various material and technology streams, with due regard to various services including
operation, maintenance, repairs and rehabilitation aspects throughout the service life of the building.
This Code, besides prescribing the various provisions, also allows freedom of action to adopt appropriate practices
and provides for building planning, designing and construction for absorbing traditional practices as well as
latest developments in knowledge in the various disciplines as relevant to a building including computer aided
and/or other modern sensors aided activities in the various stages of conceptualization, planning, designing,
constructing, maintaining and repairing the buildings. India being a large country with substantial variations
from region to region, this Code has endeavoured to meet the requirements of different regions of the country,
both urban and rural, by taking into consideration factors, such as, climatic and environmental conditions,
geographical terrain, proneness to natural disasters, ecologically appropriate practices, use of eco-friendly materials,
reduction of pollution, protection and improvement of local environment and also socio-economic considerations,
towards the creation of sustainable human settlements.
This Part of the Code dealing with 'integrated approach' is being included for the first time. It gives an overall
direction for practical applications of the provisions of different specialized aspects of spatial planning, designing
and construction of buildings, creation of services, and proposes an integrated approach for utilizing appropriate
knowledge and experience of qualified professionals right from the conceptualization through construction and
completion stages of a building project and indeed during the entire life cycle. The 'integrated approach' should
not only take care of functional, aesthetic and safety aspects, but also the operational and maintenance requirements.
Also, cost optimization has to be achieved through proper selection of materials, techniques, equipment
installations, etc. Further, value engineering and appropriate management techniques should be applied to achieve
the aim set forth for the purpose of construction of a building fully meeting the specified and implied needs of
spatial functions, safety and durability aspects, life and health safety, comfort, services, etc in the building.
The aim of the 'integrated approach 7 is to get the maximum benefit from the building apd its services in terms of
quality, timely completion and cost-effectiveness. In the team approach which is an essential pre-requisite for
integrated approach, the aim clearly is to maximize the efficiency of the total system through appropriate
optimization of each of its sub- systems. In other words, in the team, the inputs from each of the professional
disciplines have to be so optimized that the total system's efficiency becomes the maximum. It may be re-
emphasized that maximizing the efficiencies of each sub-system may not necessarily assure the maximization of
the efficiency of the total system. It need hardly to be stated that specified or implied safety will always get
precedence over functional efficiency and economy. Further, progressive approach such as that relating to the
concept of intelligent buildings would be best taken care of by the 'integrated approach' as laid down in this Part.
Quality systems approach and certification thereunder covering the various dimensions brought out above may
go a long way in achieving the above goal of real integrated approach.
PART INTEGRATED APPROACH
NATIONAL BUILDING CODE OF INDIA
PART INTEGRATED APPROACH — PREREQUISITE FOR
APPLYING PROVISIONS OF THE CODE
1 SCOPE
This Part covers guidelines to be followed for judicious
implementation of the provisions of various Parts/
Sections of the Code.
2 TERMINOLOGY
2.0 For the purpose of this Part, the following
definitions and those given in Part 1 'Definitions' shall
apply.
2.1 Authority Having Jurisdiction — The Authority
which has been created by a statute and which, for the
purpose of administering the Code/Part, may authorize
a committee or an official or an agency to act on its
behalf; hereinafter called the 'Authority'.
2.2 Building — Any structure for whatsoever purpose
and of whatsoever materials constructed and every part
thereof whether used as human habitation or not and
includes foundation, plinth, walls, floors, roofs,
chimneys, plumbing and building services, fixed
platforms, VERANDAH, balcony, cornice or projection,
part of a building or anything affixed thereto or any
wall enclosing or intended to enclose any land or space
and signs and outdoor display structures. Tents/
SHAMIANAHS/PANDALS, tarpaulin shelters, etc,
erected for temporary and ceremonial occasions shall
not be considered as building.
2.3 Owner — Person or body having a legal interest
in land and/or building thereon. This includes free
holders, leaseholders or those holding a sub-lease
which both bestows a legal right to occupation and
gives rise to liabilities in respect of safety or building
condition.
In case of lease or sub-lease holders, as far as ownership
with respect to the structure is concerned, the structure
of a flat or structure on a plot belongs to the allottee/
lessee till the allotment/lease subsists.
NOTE — For the purpose of the Code, the word 'owner' will
also cover the generally understood terms like 'client', 'user',
etc.
3 GENERAL
3.1 Buildings, shall be classified as Residential,
Educational, Institutional, Assembly, Business,
Mercantile, Industrial, Storage and Hazardous in
groups and sub-division as classified in Part 4 Tire
and Life Safety'.
For further sub-classification of buildings and various
related provisions thereof with respect to administration;
development control rules and general building
requirements; building materials; fire and life safety;
structural design; constructional practices and safety;
building and plumbing services; and landscaping, signs
and outdoor display structures, other parts/sections of
the Code may be referred to.
3.2 The scope of various Parts/Sections of the Code
which cover detailed provisions on different aspects
of development of land/building construction activity,
are given in Annex A, with a view to providing an
overview for the users of the Code.
4 TEAM APPROACH
A land development/building project comprises the
following major stages:
a) Location/siting,
b) Conceptualization and planning,
c) Designing and detailing,
d) Construction/execution, and
e) Maintenance and repair.
Each stage necessarily requires professionals of many
disciplines who should work together as a well
coordinated team to achieve the desired product
delivery with quality, in an effective manner.
Appropriate multi-disciplinary teams need to be
constituted to successfully meet the requirements of
different stages. Each team may comprise need based
professionals out of the following depending upon the
nature, magnitude and complexity of the project:
a) Architect,
b) Civil engineer,
c) Structural engineer,
d) Electrical engineer,
e) Plumbing engineer,
f) Fire protection engineer,
g) HVAC engineer,
h) Environment specialist,
j) Town planner,
k) Urban designer,
m) Landscape architect,
n) Security system specialist,
p) Interior designer,
q) Quantity surveyor,
r) Project/construction manager, and
s) Other subject specialist(s).
PART INTEGRATED APPROACH
4.1 Design Team
In building projects various aspects like form; space
planning; aesthetics; fire and life safety; structural
adequacy; plumbing services; lighting and natural
ventilation; electrical and allied installations; air
conditioning, heating and mechanical ventilation;
acoustics, sound insulation and noise control;
installation of lifts and escalators; building automation;
data and voice communication; other utility services
installations; landscape planning and design; urban
planning; etc need to be kept in view right at the
concept stage. The project requiring such multi-
disciplinary inputs need a co-ordinated approach
among the professionals for proper integration of
various design inputs. For this, and to take care of the
complexities of multi-disciplinary requirements, a
design team of professionals from required disciplines
shall be constituted at the appropriate stage. Here, it is
desirable that the multi-disciplinary integration is
initiated right from the concept stage. The team shall
finalize the plan. The composition of the team shall
depend on the nature and magnitude of the project.
Design is an evolutionary and participatory process,
where participation of owner constitutes a very
important input at all stages, and the same shall be
ensured by the design team.
To ensure proper implementation of the design, the
design team, may be associated during the construction/
execution stage.
4.2 Project Management and Construction
Management Teams
The objective of project management or construction
management is primarily to achieve accomplishment
of project in accordance with the designs and
specifications in a stipulated time and cost framework,
with a degree of assurance prior to commencement and
satisfaction on accomplishment.
For large projects, separate teams of experienced
professionals from the required disciplines may
be constituted for project management and for
construction management depending upon the
complexities of the project. However, for smaller
projects these teams may be combined. The teams shall
be responsible for day-to-day execution, supervision,
quality control, etc and shall ensure inter-disciplinary
co-ordination during the construction stage. The team
shall be responsible to achieve satisfactory completion
of the project with regard to cost, time and quality.
Some members of the design team may also be
included in the project management team and/or
associated actively during the project execution stage.
It is important that leaders and members of project
management/construction management teams,
depending on the size and complexity of the project,
are carefully selected considering their qualification,
experience and expertise in these fields.
4.3 Operation and Maintenance Team
Operation, maintenance and repairs also require a
multi-disciplinary approach to ensure that all the
requirements of the users are satisfactorily. met. During
maintenance and repairs, the jobs requiring inter-
disciplinary co-ordination have to be executed in such
a manner as not only to cause least inconvenience to
the user but also to ensure that there is no mismatch or
damage to the structure, finishings, fittings and fixtures.
For carrying out routine maintenance/repair jobs,
utilization of the services of trained technicians
preferably having multi-disciplinary skills should be
encouraged.
Special repairs, rehabilitation and retrofitting are
specialized jobs which demand knowledge of the
existing structure/installations. Association of
concerned specialists may be helpful for these works.
The Operation and Maintenance Team may also be
known as Asset Management or Estate Management
Team.
5 PLAN^mVG,DESIGMNGA]^roDEVELOPMENT
5.1 The main functions of design team (see 4.1)
constituted for the planning, designing and development,
are as under:
a) Formalization of design brief in consultation
with the owner.
b) Site investigation/survey.
c) Preparation of alternative concept designs.
d) Selection of a concept in consultation with
and with the consent of owner.
e) Sizing the system.
f) Development of design, covering :
1) Integration of architecture, structure and
services,
2) Synthesis of requirements of each
discipline, and
3) Interaction with each other and with the
owner.
g) Preparation of preliminary designs and
drawings and obtaining owner's approval.
h) Preparation of preliminary cost estimates for
approval of owner,
j) Preparation of work-breakdown structure and
programme for pre-construction activities,
k) Assisting client to obtain approvals of the
Authority,
m) Preparation of detailed specification and
NATIONAL BUILDING CODE OF INDIA
construction working drawings with integration
of engineering inputs of all concerned
disciplines,
n) Preparation of detailed design of each
discipline for various services,
p) Peer review/proof checking of the drawings/
designs in case of important projects,
depending upon their complexity and
sensitivity.
q) Preparation of detailed cost estimate,
r) Obtaining final approval of client.
s) Preparation of bill of quantities, specifications
and tender documents.
5.2 The following considerations, as may be
applicable to the project, may be considered during
planning, notwithstanding other relevant aspects
specifically prescribed in concerned parts/sections of
this Code; these considerations in general are with the
objective of addressing to the important issues like
environmental protection, energy conservation,
cultural issues, creating barrier free built-environment,
safety aspects, etc, all of these leading towards
sustainable development, and have to be applied with
due regard to the specific requirements of size and type
of project:
a) Geoclimatic, geological and topographical
features.
b) Varied sociological pattern of living in the
country.
c) Effective land use to cater to the needs of the
society in a most convenient manner.
d) Modular planning and standardization to
take care of future planning giving due
consideration to the specified planning
controls.
e) Emphasis on daylight utilization, natural
ventilation, shielding, and window area
and its disposition; daylighting to be
supplemented with an integrated design of
artificial lighting.
f) Optimum utilization of renewable energy
sources duly integrated in the overall energy
system design; with consideration of active
and passive aspects in building design
including thermal performance of building
envelope.
g) Rain water harvesting, and use of appropriate
building materials considering aspects
like energy consumption in production,
transportation and utilization, recyclability,
etc for promoting sustainable development.
h) Requisite mandatory provisions for
handicapped persons.
j) Acoustical controls for buildings and the
surroundings,
k) Promotion of artwork in buildings, specially
buildings of importance,
m) Due cognizance of recommendations of the
Archeological Survey of India with regard to
national monuments and construction in
archeologically important sites,
n) Due cognizance of relevant provisions of
applicable coastal zone regulation act.
p) Conservation of heritage structures and areas,
q) Environmental and social impact analysis.
r) Design of services with emphasis on aspects
of energy efficiency, environment friendliness
and maintainability.
s) Integrated waste management,
t) Voice and data communication, automation
of building services, and intelligent building;
use of security and surveillance system in
important and sensitive buildings, such as,
access control for the people as well as for
vehicle,
u) Interlinking of fire alarm system, fire
protection system, security system, ventilation,
electrical systems, etc.
v) Analysis of emergency power, standby power
requirement and captive power systems,
w) Cost optimization through techniques like
value engineering.
y) Adoption of innovative technologies giving
due consideration to constructability and
quality aspects.
z) Instrumentation of buildings and monitoring
and use of information so generated to effect
improvements in planning and design of
future building projects.
6 CONSTRUCTION/EXECUTION
(ACTUALIZATION)
6.1 The main functions of the teams (see 4.2)
constituted for Project Management/Construction
Management may be, to :
a) specify criteria for selection of constructors;
b) specify quality control, quality audit system
and safety system;
c) short-list constructors;
d) have pre-bid meetings with the intending
constructors;
e) receive and evaluate tenders;
f) select constructors;
g) execution and supervision;
h) monitor quality, time and cost control;
PART INTEGRATED APPROACH
j) prepare/certify the completion (as-built)
drawings; and
k) ensure availability of operation manuals for
field use.
6.2 Apart from the specific provisions laid down in
the concerned Parts/Sections of the Code, the following
considerations, as may be applicable to the project
concerned, shall be given due attention:
a) Adopting scientific principles of construction
management, quality management, cost and
time control.
b) Engagement of executing and supervising
agencies, which meet the specified norms of
skills, specialization, experience, resource-
fulness, etc for the work.
c) Ensuring inter-disciplinary co-ordination
during construction.
d) Contract management and techno-legal
aspects.
e) Completion, commissioning and trial run of
installations/equipments and their operation
and maintenance through the suppliers/other
teams, where necessary.
f) Make available shop drawings as well as as-
built drawings for the building and services.
g) Arrange all maintenance and operation
manual from the concerned suppliers/
manufacturers.
6.3 The team of professionals (see 4.2) shall work
and monitor the project activities for successful
construction/execution of the project with regard to
cost, time, quality and safety.
7 OPERATION AND MAINTENANCE
7.1 The team of professionals (see 4.3) shall set up a
system of periodic maintenance and upkeep of
constructed buildings.
7.2 The operation and maintenance team shall be
responsible for preparation/application of operation
and maintenance manual, and draw maintenance
schedule/frequencies and guidelines for maintenance
personnel. Apart from the specific provisions laid down
in concerned Parts/Sections of the Code, the following,
as may be applicable to the project concerned shall
additionally be taken into account:
a) Periodic validation of buildings by competent
professionals through inspection of the
buildings in respect of structural safety and
safety of electrical and other installations and
ensuring that all fire safety equipments/
systems are in proper working condition.
b) Preparation of preventive maintenance
schedules for all installations in the building
and strictly following the same; the record of
the preventive maintenance to be properly
kept.
c) Ensuring inter-disciplinary co-ordination
during maintenance and repairs; deployment
of trained personnel with multi-disciplinary
skills to be encouraged.
d) Condition survey of structures and
installations, identification of distress of
various elements and initiating plans for
rehabilitation/retrofitting well in time.
7.3 The proposals for rehabilitation/retrofitting should
be prepared after detailed investigations through visual
inspection, maintenance records and testing as required
and got executed through specialized agencies
under the guidance and supervision of competent
professionals.
NATIONAL BUILDING CODE OF INDIA
ANNEX A
(Clause 3.2)
BRIEF DETAILS OF THE COVERAGE OF VARIOUS PROVISIONS UNDER
DIFFERENT OTHER PARTS/SECTIONS OF THIS CODE
A-l PART 1 DEFINITIONS
It lists the terms appearing in all the Parts/Sections of
the Code. However, some common definitions are
reproduced in this Part also.
A-2 PART 2 ADMINISTRATION
It covers the administrative aspects of the Code, such
as applicability of the Code, organization of building
department for enforcement of the Code, procedure
for obtaining development and building permits, and
responsibility of the owner and all professionals
involved in the planning, design and construction of
the building.
A-3 PART 3 DEVELOPMENT CONTROL RULES
AND GENERAL BUILDING REQUIREMENTS
It covers the development control rules and general
building requirements for proper planning and design
at the layout and building level to ensure health safety,
public safety and desired quality of life.
A-4 PART 4 FIRE AND LIFE SAFETY
It covers the requirements for fire prevention, life
safety in relation to fire, and fire protection of
buildings. The Code specifies planning and
construction features and fire protection features for
all occupancies that are necessary to minimize danger
to life and property.
A-5 PART 5 BUILDING MATERIALS
It covers the requirements of building materials and
components, and criteria for accepting new or
alternative building materials and components.
A-6 PART 6 STRUCTURAL DESIGN
This Part through its seven sections provides for
structural adequacy of buildings to deal with both
internal and external environment, and provide
guidance to engineers/structural engineers for varied
usage of material/technology types for building
design.
A-6.1 Section 1 Loads, Forces and Effects
it covers basic design loads to be assumed in the design
of buildings. The live loads, wind loads, seismic loads,
snow loads and other loads, which are specified therein,
are minimum working loads which should be taken
into consideration for purposes of design.
A-6.2 Section 2 Soils and Foundations
It covers structural design (principles) of all building
foundations, such as, raft, pile and other foundation
systems to ensure safety and serviceability without
exceeding the permissible stresses of the materials of
foundations and the bearing capacity of the supporting
soil.
A-6.3 Section 3 Timber and Bamboo
A-6.3.1 Section 3A Timber
It covers the use of structural timber in structures or
elements of structures connected together by fasteners/
fastening techniques.
A-6.3.2 Section 3B Bamboo
It covers the use of bamboo for constructional purposes
in structures or elements of the structure, ensuring
quality and effectiveness of design and construction
using bamboo. It covers minimum strength data,
dimensional and grading requirements, seasoning,
preservative treatment, design and jointing techniques
with bamboo which would facilitate scientific
application and long-term performance of structures.
It also covers guidelines so as to ensure proper
procurement, storage, precautions and design
limitations on bamboo.
A-6.4 Section 4 Masonry
It covers the structural design aspects of unreinforced
load bearing and non-load bearing walls, constructed
using various bricks, stones and blocks permitted in
accordance with this Section. This, however, also
covers provisions for design of reinforced brick and
reinforced brick concrete floors and roofs. It also
covers guidelines regarding earthquake resistance of
low strength masonry buildings.
A-6.5 Section 5 Concrete
A-6.5.1 Section 5A Plain and Reinforced Concrete
It covers the general structural use of plain and
reinforced concrete.
A-6.5.2 Section 5B Prestressed Concrete
It covers the general structural use of prestressed
concrete. It covers both work carried out on site and
the manufacture of precast prestressed concrete
units.
PART INTEGRATED APPROACH
A-6.6 Section 6 Steel
It covers the use of structural steel in general building
construction including the use of hot rolled steel
sections and steel tubes.
A-6.7 Section 7 Prefabrication, Systems Building
and Mixed/Composite Construction
A-6.7.1 Section 7 A Prefabricated Concrete
It covers recommendations regarding modular
planning, component sizes, prefabrication systems,
design considerations, joints and manufacture, storage,
transport and erection of prefabricated concrete
elements for use in buildings and such related
requirements for prefabricated concrete.
A-6.7.2 Section 7B Systems Building and Mixed/
Composite Construction
It covers recommendations regarding modular
planning, component sizes, joints, manufacture,
storage, transport and erection of prefabricated
elements for use in buildings and such related
requirements for mixed/composite construction.
A-7 PART 7 CONSTRUCTIONAL PRACTICES
AND SAFETY
It covers the constructional planning, management and
practices in buildings; storage, stacking and handling
of materials and safety of personnel during construction
operations for all elements of a building and demolition
of buildings. It also covers guidelines relating to
maintenance management, repairs, retrofitting and
strengthening of buildings. The objective can be best
achieved through proper coordination and working by
the project management and construction management
teams.
A-8 PART 8 BUILDING SERVICES
This Part through its five elaborate sections on utilities
provides detailed guidance to concerned professionals/
utility engineers for meeting necessary functional
requirements in buildings.
A-8.1 Section 1 Lighting and Ventilation
It covers requirements and methods for lighting and
ventilation of buildings.
A-8.2 Section 2 Electrical and Allied Installations
It covers the essential requirements for electrical and
allied installations in buildings to ensure efficient use
of electricity including safety from fire and shock. This
Section also includes general requirements relating to
lightning protection of buildings.
A-8.3 Section 3 Air Conditioning, Heating and
Mechanical Ventilation
This Section covers the design, construction and
installation of air conditioning and heating systems and
equipment installed in buildings for the purpose
of providing and maintaining conditions of air
temperature, humidity, purity and distribution suitable
for the use and occupancy of the space.
A-8.4 Section 4 Acoustics, Sound Insulation and
Noise Control
It covers requirements and guidelines regarding
planning against noise, acceptable noise levels and the
requirements for sound insulation in buildings with
different occupancies.
A-8.5 Section 5 Installation of Lifts and
Escalators
It covers the essential requirements for the installation,
operation, maintenance and also inspection of lifts
(passenger lifts, goods lifts, hospital lifts, service lifts
and dumb-waiter) and escalators so as to ensure safe
and satisfactory performance.
A-9 PART 9 PLUMBING SERVICES
This Part through its two sections gives detailed
guidance to concerned professionals/plumbing
engineers with regard to plumbing and other related
requirements in buildings.
A-9.1 Section 1 Water Supply, Drainage and
Sanitation (Including Solid Waste Management)
It covers the basic requirements of water supply for
residential, business and other types of buildings,
including traffic terminal stations. This Section also
deals with general requirements of plumbing connected
to public water supply and design of water supply
systems.
It also covers the design, layout, construction and
maintenance of drains for foul water, surface water
and sub-soil water and sewage; together with all
ancillary works, such as connections, manholes and
inspection chambers used within the building and from
building to the connection to a public sewer, private
sewer, individual sewage-disposal system, cess-pool,
soakaway or to other approved point of disposal/
treatment work. It also includes the provisions on solid
waste management.
A-9.2 Section 2 Gas Supply
It covers the requirements regarding the safety of persons
and property for all piping uses and for all types of gases
used for fuel or lighting purposes in buildings.
10
NATIONAL BUILDING CODE OF INDIA
A-10 PART 10 LANDSCAPING, SIGNS AND A-10.2 Section 2 Signs and Outdoor Display
OUTDOOR DISPLAY STRUCTURES Structures
A-10.1 Section 1 Landscape Planning and Design It covers the requirements with regard to public safety,
It covers requirements of landscape planning and struct » ral safety and fire safety of all signs and outdoor
design with the view to promoting quality of outdoor dls P la y structures including the overall aesthetical
built environment and protection of land and its as P ects of imposition of signs and outdoor display
resources structures in the outdoor built environment.
PART INTEGRATED APPROACH 11
NATIONAL BUILDING CODE OF INDIA
PART 1 DEFINITIONS
BUREAU OF INDIAN STANDARDS
National Building Code Sectional Committee, CED 46
FOREWORD
Each Part or Section of the National Building Code gives the definitions of the special terms used in it. These
definitions may be found in the clause Terminology' normally placed immediately after the 'Scope' in each
Part/Section. However, users may find this part very convenient for reference as it gives the alphabetically
arranged list of terms defined in all the parts along with the location of the definition.
PART 1 DEFINITIONS
NATIONAL BUILDING CODE OF INDIA
PART 1 DEFINITIONS
1 SCOPE
This Part lists the terms appearing in all the Parts/
Sections of the National Building Code of India. The
terms have been arranged in their alphabetical order.
The Part(s)/Section(s) in which these terms are
appearing, have been indicated against the terms.
However, some common definitions are reproduced
in this part also; the definitions being placed
immediately below the term concerned.
Abandoned Sign — Part 10/Section 2
Access — Part 3
Access Panel — Part 9/Section 1
Accessory — Part 8/Section 2
Accessory Use — Part 2, Part 3
Any use of the premises subordinate to the principal
use and customarily incidental to the principal use.
Advertising Sign — Part 10/Section 2
Air Change per Hour — Part 8/Section 1
Air Conditioning — Part 8/Section 3
Air Gap — Part 9/Section 1
Air-Break — Part 9/Section 1
Alteration — Part 2, Part 3
A change from one occupancy to another, or a
structural change, such as an addition to the area or
height, or the removal of part of a building, or any
change to the structure, such as the construction of,
cutting into or removal of any wall, partition, column,
beam, joist, floor or other support, or a change to or
closing of any required means of ingress or egress or a
change to the fixtures or equipment.
Alternating Current Variable Voltage (ACW) Control
— Part 8/Section 5
Alternating Current Variable Voltage Variable
Frequency (ACVWF) Control — Part 8/Section 5
Altitude (6) — Part 8/Section 1
Ambient Noise — Part 8/Section 4
Anatomical Purpose Definitions for Engineers —
Part 6/Section 3B
Apparatus — Part 8/Section 2
Appliance — Part 8/Section 2
Appliance Valve — Part 9/Section 2
Approved — Part 2, Part 3, Part 10/Section 2
Approved by the Authority having jurisdiction.
Area of Special Control — Part 10/Section 2
Atmospheric Pressure — Part 8/Section 3
Audible Frequency Range — Part 8/Section 4
Authority Having Jurisdiction — Part 2, Part 3,
Part 6/Section 7B, Part 9/Section 1, Part 9/Section 2,
Part 10/Section 2
The Authority which has been created by a statute and
which, for the purpose of administering the Code/Part,
may authorize a committee or an official or an agency
to act on its behalf; hereinafter called the 'Authority'.
Automatic Fire Detection and Alarm System — Part 4
Automatic Operation — Part 8/Section 5
Automatic Sprinkler System — Part 4
Available Head — Part 9/Section 1
Avenue — Part 10/Section 1
A-Weighted Sound Pressure Level, L A — Part 8/
Section 4
A-Weighted Sound Pressure, p A — Part 8/Section 4
Axial Flow Fan — Part 8/Section 1
Azimuth (())) — Part 8/Section 1
B
Back Fill — Part 6/Section 2
Back Siphonage — Part 9/Section 1
Back to Back Cluster — Part 3
Back Up — Part 9/Section 1
Backflow Prevention Device — Part 9/Section 1
Backflow — Part 9/Section 1
Background Noise — Part 8/Section 4
Balcony — Part 3
Baluster — Part 8/Section 5
Balustrade — Part 8/Section 5
Bamboo — Part 6/Section 3B
Bamboo Borer (Bamboo GHOON)— Part 6/Section 3B
Bamboo Clump — Part 6/Section 3B
Bamboo Culm — Part 6/Section 3B
Bamboo Mat Board — Part 6/Section 3B
Banner — Part 10/Section 2
Banner Sign — Part 10/Section 2
Barrel — Part 9/Section 1
Base — Part 9/Section 1
Basement or Cellar — Part 3
Basic Module — Part 6/Section 7A, Part 6/Section 7B
Basic or Ultimate Stress — Part 6/Section 3,
Part 6/Section 3B
Batter Pile (Raker Pile) — Part 6/Section 2
Battery of Fixtures — Part 9/Section 1
PART 1 DEFINITIONS
Beam — Part 6/Section 3B
Beam, Built-Up-Laminated — Part 6/Section 3
Beam, Glued-Laminated — Part 6/Section 3
Bearing Capacity, Safe — Part 6/Section 2
Bearing Capacity, Ultimate — Part 6/Section 2
Bearing Pile — Part 6/Section 2
Bearing Pressure, Allowable (Gross or Net) — Part 6/
Section 2
Bearing Pressure, Allowable — Part 6/Section 2
Bearing Pressure, Safe — Part 6/Section 2
Bed Block — Part 6/Section 4
Bedding — Part 9/Section 1
Benching — Part 9/Section 1
Bond — Part 6/Section 4
Bored Cast in-situ Pile — Part 6/Section 2
Bored Compaction Pile — Part 6/Section 2
Bored Pile — Part 6/Section 2
Bottom Car Clearance — Part 8/Section 5
Bottom Car Runby — Part 8/Section 5
Bottom Coutnerweight Runby — Part 8/Section 5
Boucherie Process — Part 6/Section 3B
Branch — Part 9/Section 1
Branch Soil Pipe (BSP) — Part 9/Section 1
Branch Soil Waste Pipe (BSWP) — Part 9/Section 1
Branch Ventilating Pipe (BVP) — Part 9/Section 1
Branch Waste Pipe (BWP) — Part 9/Section 1
Break-in — Part 8/Section 4
Breaking Strength — Part 6/Section 3B
Break-out — Part 8/Section 4
Brightness Ratio or Contrast — Part 8/Section 1
Broad Band Noise — Part 8/Section 4
Buffer — Part 10/Section 1, Part 8/Section 5
Building (House) Drain — Part 9/Section 1
Building (House) Drain-Combined — Part 9/Section 1
Building (House) Drain-Sanitary — Part 9/Section 1
Building (House) Drain-Storm — Part 9/Section 1
Building (House) Sewer — Part 9/Section 1
Building (House) Sub-Drain — Part 9/Section 1
Building (House) Trap — Part 9/Section 1
Building — Part 2, Part 3, Part 4
Any structure for whatsoever purpose and of
whatsoever materials constructed and every part
thereof whether used as human habitation or not and
includes foundation, plinth, walls, floors, roofs,
chimneys, plumbing and building services, fixed
platforms, verandah, balcony, cornice or projection,
part of a building or anything affixed thereto or any
wall enclosing or intended to enclose any land or space
and signs and outdoor display structures. Tents/
SHAMIANAHS, tarpaulin shelters, etc, erected for
temporary and ceremonial occasions with the
permission of the Authority shall not be considered as
building.
Building, Height of— Part 2, Part 3, Part 4
The vertical distance measured, in the case of flat roofs
from the average level of the ground around and
contiguous to the building or as decided by the
Authority to the terrace of last livable floor of the
building adjacent to the external walls; and in the case
of pitched roofs, up to the point where the external
surface of the outer wall intersects the finished surface
of the sloping roof, and in the case of gables facing the
road, the mid-point between the eaves level and the
ridge. Architectural features serving no other function
except that of decoration shall be excluded for the
purpose of measuring heights.
Building Line — Part 2, Part 3, Part 10/Section 2
The line up to which the plinth of a building adjoining
a street or an extension of a street or on a future street
may lawfully extend. It includes the lines prescribed,
if any, in any scheme. The building line may change
from time-to-time as decided by the Authority.
Buildings Related Illnesses (BRI) — Part 8/Section 3
Bunched — Part 8/Section 2
Cabin — Part 3
Cable — Part 8/Section 2
Cable Armoured — Part 8/Section 2
Cable, Crossed Linked Insulated — Part 8/Section 2
Cable, Flexible — Part 8/Section 2
Cable, Lead-Covered — Part 8/Section 2
Cable, Metal-Sheathed — Part 8/Section 2
Cable, PVC-Insulated — Part 8/Section 2
Cable, PVC-Sheathed — Part 8/Section 2
Cable, Tough Rubber-Sheathed (Cable, TRS) — Part 8/
Section 2
Cable, Weatherproof— Part 8/Section 2
Cable, XLPE — Part 8/Section 2
Call Indicator — Part 8/Section 5
Candela (cd) — Part 8/Section 1
Canopy — Part 3
Canopy Sign — Part 10/Section 2
Car Bodywork — Part 8/Section 5
Car Door Electric Contact — Part 8/Section 5
Car Platform — Part 8/Section 5
Car Switch Operation — Part 8/Section 5
Carframe — Part 8/Section 5
Carpet Area — Part 3
NATIONAL BUILDING CODE OF INDIA
Ceiling Rose — Part 8/Section 2
Cell — Part 6/Section 3B
Cellular Concrete — Part 6/Section 7B, Part 6/
Section 7A
Cellulose — Part 6/Section 3B
Central Field — Part 8/Section 1
Centre Internode — Part 6/Section 3B
Centrifugal Fan — Part 8/Section 1
Cesspool — Part 9/Section 1
Chair — Part 9/Section 1
Channel — Part 9/Section 1
Characteristic Load — Part 6/Section 3B
Characteristic Strength — Part 6/Section 3B
Check — Part 6/Section 3
CHHAJJA — Part 3
Chimney — Part 3
Chowk or Courtyard — Part 3
Chowk, Inner — Part 3
Chowk, Outer — Part 3
Chute — Part 9/Section 1
Circuit — Part 8/Section 2
Circuit Breaker — Part 8/Section 2
Circuit Final, Sub — Part 8/Section 2
Cistern — Part 9/Section 1
Clay — Part 6/Section 2
Clay, Firm — Part 6/Section 2
Clay, Soft — Part 6/Section 2
Clay, Stiff— Part 6/Section 2
Cleaning Eye — Part 9/Section 1
Clear Design Sky — Part 8/Section 1
Clear Waste Water — Part 9/Section 1
Clearance — Part 8/Section 5
Cleat — Part 8/Section 2
Cleavability — Part 6/Section 3B
Cleavage — Part 6/Section 3B
Climber (Creeper/Vine) — Part 10/Section 1
Closed Clusters — Part 3
Closed Sign — Part 10/Section 2
Cluster — Part 3
Cluster Court Town House — Part 3
Cluster Plot — Part 3
Collapse — Part 6/Section 3B
Collection Chamber — Part 9/Section 1
Column — Part 6/Section 3B
Column, Pier and Buttress — Part 6/Section 4
Columnar — Part 10/Section 1
Combination Sign — Part 10/Section 2
Combustible Material — Part 4, Part 10/Section 2
The material which either burns itself or adds heat to a
fire, when tested for non-combustibility in accordance
with accepted standard [4(1)].
Common Rafter — Part 6/Section 3B
Communication Pipe — Part 9/Section 1
Components — Part 6/Section 7A, Part 6/Section 7B
Composite Members — Part 6/Section 7A, Part 6/
Section 7B
Compression Wood — Part 6/Section 3
Conductor of a Cable or Core — Part 8/Section 2
Conductor, Aerial — Part 8/Section 2
Conductor, Bare — Part 8/Section 2
Conductor, Earthed — Part 8/Section 2
Conductor, Insulated — Part 8/Section 2
Connection — Part 9/Section 1
Connector — Part 8/Section 2
Connector Box or Joint Box — Part 8/Section 2
Connector for Portable Appliances — Part 8/Section 2
Conservation (Preservation) — Part 10/Section 1
Consumer — Part 9/Section 1
Consumer's Pipe — Part 9/Section 1
Consumer's Terminals — Part 8/Section 2
Contaminants — Part 8/Section 1
Contour — Part 10/Section 1
Contour Interval — Part 10/Section 1
Contour Line — Part 10/Section 1
Control — Part 8/Section 5
Conventional Symbols — Part 8/Section 2
Conversion — Part 2
Cooking Alcove — Part 3
Cord, Flexible — Part 8/Section 2
Core of a Cable — Part 8/Section 2
Counterweight — Part 8/Section 5
Cover — Part 9/Section 1
Covered Area — Part 3, Part 4
Ground area covered by the building immediately
above the plinth level. The area covered by the
following in the open spaces is excluded from covered
area:
a) garden, rockery, well and well structures,
plant nursery, waterpool, swimming pool (if
uncovered), platform round a tree, tank,
fountain, bench, CHABUTARA with open top
and unenclosed on sides by walls and the
like;
b) drainage culvert, conduit, catch-pit, gully pit,
chamber, gutter and the like;
c) compound wall, gate, unstoreyed porch and
portico, slide, swing, uncovered staircases,
PART 1 DEFINITIONS
ramp areas covered by CHHAJJA and the like;
and
d) watchman's booth, pumphouse, garbage
shaft, electric cabin or sub-stations, and such
other utility structures meant for the services
of the building under consideration.
NOTE — For the purpose of this part, covered area
equals the plot area minus the area due for open spaces
in the plot.
Crookedness — Part 6/Section 3B
Cross Wall — Part 6/Section 3B
Cross-Connection — Part 9/Section 1
Cross-Sectional Area of Masonry Unit — Part 6/
Section 4
Cross-Talk — Part 8/Section 4
Crown of Trap — Part 9/Section 1
'Cul-de-Sac' Cluster — Part 3
Curtain Wall — Part 6/Section 4
Curvature — Part 6/Section 3B
Customer's/Consumer's Connection — Part 9/
Section 2
Cut-off Level — Part 6/Section 2
Cut-out — Part 8/Section 2
D
Damp Situation — Part 8/Section 2
Daylight Area — Part 8/Section 1
Daylight Factor — Part 8/Section 1
Daylight Penetration — Part 8/Section 1
Dead — Part 8/Section 2
Dead Knot — Part 6/Section 3
Decay or Rot — Part 6/Section 3
Decayed Knot — Part 6/Section 3
Decibels — Part 8/Section 4
Deciduous Tree — Part 10/Section 1
Deep Manhole — Part 9/Section 1
Definitions of Defects in Bamboo — Part 6/Section 3B
Definitions of Defects in Timber — Part 6/Section 3
Deflector Shieve — Part 8/Section 5
Delamination — Part 6/Section 3B
Density — Part 3
Depth of Manhole — Part 9/Section 1
Detached Building — Part 3
Development — Part 2, Part 3
'Development' with grammatical variations means the
carrying out of building, engineering, mining or other
operations in, or over, or under land or water, or in
the use of any building or land, and includes
redevelopment and layout and subdivision of any land;
and 'to develop' shall be construed accordingly.
Dewpoint Temperature — Part 8/Section 3
Diameter — Part 9/Section 1
The nominal internal diameter of pipes and fittings.
Diameter of Knot — Part 6/Section 3
Diaphragm, Structural — Part 6/Section 3B
Dilution Ventilation — Part 8/Section 1
Direct Earthing System — Part 8/Section 2
Direct Solar Illuminance — Part 8/Section 1
Direct Tap — Part 9/Section 1
Direction Sign — Part 10/Section 2
Discolouration — Part 6/Section 3, Part 6/Section 3B
Discrimination (Over-Current Discrimination) —
Part 8/Section 2
Distance Area of Resistance Area (for Earth Electrode
only) — Part 8/Section 2
Distribution Board — Part 8/Section 2
Door — Part 8/Section 5
Door Closer — Part 8/Section 5
Door Operator — Part 8/Section 5
Door, Centre Opening Sliding — Part 8/Section 5
Door, Mid-Bar Collapsible — Part 8/Section 5
Door, Single Slide — Part 8/Section 5
Door, Swing — Part 8/Section 5
Door, Two Speed Siding — Part 8/Section 5
Door, Vertical Bi-parting — Part 8/Section 5
Door, Vertical Lifting — Part 8/Section 5
Double Button (Continuous Pressure) Operation —
Part 8/Section 5
Downcomer — Part 4
Downtake Tap — Part 9/Section 1
Drain — Part 2, Part 3, Part 9/Section 1
A conduit, channel or pipe for the carriage of storm
water, sewage, waste water or other water-borne wastes
in a building drainage system.
Drain Ventilating Pipe (DVP) — Part 9/Section 1
Drainage — Part 2, Part 9/Section 1
The removal of any liquid by a system constructed for
the purpose.
Drainage Work — Part 9/Section 1
Driven Cast in-situ Pile — Part 6/Section 2
Driven Precast Pile — Part 6/Section 2
Drop Connection — Part 9/Section 1
Drop Manhole — Part 9/Section 1
Dry Bulb Temperature — Part 8/Section 1
Dry Riser — Part 4
Dry-Bulb Temperature — Part 8/Section 3
Drying Degrades in Round Bamboo — Part 6/
Section 3B
8
NATIONAL BUILDING CODE OF INDIA
Duct System — Part 8/Section 3
Duration of Load — Part 6/Section 3
Dwelling Unit/Tenement — Part 3
E
Earth — Part 8/Section 2
Earth Continuity Conductor — Part 8/Section 2
Earth Electrode — Part 8/Section 2
Earth Fault — Part 8/Section 2
Earth Leakage Circuit Breaker System — Part 8/
Section 2
Earthing Lead — Part 8/Section 2
Edge Distance — Part 6/Section 3
Effective Height — Part 6/Section 4
Effective Length — Part 6/Section 4
Effective Opening — Part 9/Section 1
Effective Temperature (ET) — Part 8/Section 1
Effective Thickness — Part 6/Section 4
Efficiency of a Pile Group — Part 6/Section 2
Egress — Part 10/Section 1
Electric Sign — Part 10/Section 2
Electrical and Mechanical Interlock — Part 8/Section 5
Electro- Mechanical Lock — Part 8/Section 5
Electronic Devices — Part 8/Section 5
Elevation — Part 10/Section 1
Emergency Lighting — Part 4
Emergency Lighting System — Part 4
Emergency Stop Push or Switch — Part 8/Section 5
Enclosed Distribution Board — Part 8/Section 2
End Distance — Part 6/Section 3, Part 6/Section 3B
End Splitting — Part 6/Section 3B
Enthalphy — Part 8/Section 3
Equivalent Continuous A — Weighted Sound Pressure
Level, L Ae T — Part 8/Section 4
Equivalent Sound Absorption Area of a Room, A —
Part 8/Section 4
Escalator — Part 8/Section 5
Escalator Installation — Part 8/Section 5
Escalator Machine — Part 8/Section 5
Escape Lighting — Part 4
Evaporative Air Cooling — Part 8/Section 3
Evergreen — Part 10/Section 1
Exhaust of Air — Part 8/Section 1
Exit — Part 3
Exotic — Part 10/Section 1
Exposed Metal — Part 8/Section 2
Exterior Sign — Part 10/Section 2
External Faces of Cluster — Part 3
External Reflected Component (ERC) — Part 8/Section 1
Facade Level — Part 8/Section 4
Factor of Safety (with Respect to Bearing Capacity) —
Part 6/Section 2
Factor of Safety — Part 6/Section 2
Feed Cistern — Part 9/Section 1
Fencing — Part 10/Section 1
Finger Joint — Part 6/Section 3
Finished Grade — Part 10/Section 1
Fire Damper — Part 8/Section 3
Fire Door — Part 4
Fire Exit — Part 4
Fire Lift — Part 4
Fire Load — Part 4
Fire Load Density — Part 4
Fire Resistance Rating — Part 4
Fire Resistance, Criteria of — Part 4
Fire Resisting Wall — Part 4
Fire Separating Wall — Part 4
*Fire Separation — Part 3, Part 4
The distance in metres measured from the external wall
of the building concerned to the external wall of any
other building on the site, or from other site, or from
the opposite side of street or other public space to the
building for the purpose of preventing the spread of
fire.
Fire Separation Wall — Part 8/Section 3
Fire Stop — Part 4
Fire Survival Cable — Part 8/Section 2
Fire Tower — Part 4
Fitting, Lighting — Part 8/Section 2
Fittings — Part 9/Section 1
Fittings shall mean coupling, flange, branch, bend, tees,
elbows, unions, waste with plug, P or S trap with vent,
stop ferrule, stop tap, bib tap, pillar tap, globe tap, ball
valve, cistern storage tank, baths, water-closets, boiler,
geyser, pumping set with motor and accessories, meter,
hydrant, valve and any other article used in connection
with water supply, drainage and sanitation.
Fixture Unit — Part 9/Section 1
Fixture Unit Drainage — Part 9/Section 1
Flame Retardant Cable — Part 8/Section 2
Flameproof Enclosure — Part 8/Section 2
Flatten Bamboo — Part 6/Section 3B
Float Operated Valve — Part 9/Section 1
Floor — Part 3
* Definitions are different.
PART 1 DEFINITIONS
The lower surface in a storey on which one normally
walks in a building. The general term 'floor' unless
specifically mentioned otherwise shall not refer to a
'mezzanine floor'.
Floor Area Ratio (FAR) — Part 3, Part 4
The quotient obtained by dividing the total covered
area (plinth area) on all floors by the area of the plot:
FAR =
Tot al covered area of all floors
Plot area
Floor Levelling Switch — Part 8/Section 5
Floor Selector — Part 8/Section 5
Floor Stopping Switch — Part 8/Section 5
Flushing Cistern — Part 9/Section 1
Foliage — Part 10/Section 1
Footing — Part 6/Section 2
Formation — Part 9/Section 1
Foundation — Part 6/Section 2
Foundation, Raft — Part 6/Section 2
Free-Field Level — Part 8/Section 4
Freestanding Sign — Part 10/Section 2
French Drain or Rubble Drain — Part 9/Section 1
Frequency — Part 8/Section 4
Fresh Air or Outside Air — Part 8/Section 1
Frost Line — Part 9/Section 1
Full Culm — Part 6/Section 3B
Fuse — Part 8/Section 2
Fuse-Element — Part 8/Section 2
G
Gallery — Part 3
Garage, Private — Part 3
Garage, Public — Part 3
Gas Fitter — Part 9/Section 2
Geared Machine — Part 8/Section 5
Gearless Machine — Part 8/Section 5
General — Part 6/Section 2, Part 10/Section 2
General Ventilation — Part 8/Section 1
General Washing Place — Part 9/Section 1
Geyser — Part 9/Section 1
Glare — Part 8/Section 1
Global Warming Potential (GWP) — Part 8/Section 3
Globe Temperature — Part 8/Section 1
Goods Lift — Part 8/Section 5
Grade — Part 10/Section 1
Gradient — Part 10/Section 1
Grading — Part 10/Section 1
Grasses — Part 10/Section 1
Gravel — Part 6/Section 2
Ground Sign — Part 10/Section 2
Groundcover — Part 10/Section 1
Group Automatic Operation — Part 8/Section 5
Group Housing — Part 3
Group Open Space — Part 3
Grout — Part 6/Section 4
Guide Rails — Part 8/Section 5
Guide Rails Fixing — Part 8/Section 5
Guide Rails Shoe — Part 8/Section 5
Gully Chamber — Part 9/Section 1
Gully Trap — Part 9/Section 1
H
Habitable Room — Part 3
Hard Landscape — Part 10/Section 1
Hardy Plant — Part 10/Section 1
Harmonics — Part 8/Section 2
Haunching — Part 9/Section 1
Hedge — Part 10/Section 1
Heel Rest Bend or Duck-Foot Bend — Part 9/Section 1
Hemi Cellulose — Part 6/Section 3B
Herb — Part 10/Section 1
High Altitudes — Part 9/Section 1
High Rise Building — Part 4
Highway Authority — Part 9/Section 1
Hollow Unit — Part 6/Section 4
Horizontal Exit — Part 4
Horizontal Pipe — Part 9/Section 1
Hospital Lift — Part 8/Section 5
Hot Water Tank — Part 9/Section 1
Humidification — Part 8/Section 1
Humidity, Absolute — Part 8/Section 1
Humidity, Relative — Part 8/Section 1
Hydronic Systems — Part 8/Section 3
I
Identification Sign — Part 10/Section 2
Illuminance — Part 8/Section 1
Illuminated Sign — r Part 10/Section 2
Impact Sound Pressure Level, L. — Part 8/Section 4
Increments — Part 6/Section 7 A, Part 6/Section 7B
Independent Cluster — Part 3
Indoor Air Quality (IAQ) — Part 8/Section 3
Indoor Ambient Noise — Part 8/Section 4
Inflammable — Part 8/Section 2
Informational Sign — Part 10/Section 2
Ingress — Part 10/Section 1
Inlet Hopper — Part 9/Section 1
Inner Diameter — Part 6/Section 3B
10
NATIONAL BUILDING CODE OF INDIA
Insertion Loss (L^) — Part 8/Section 4
Inside Location — Part 6/Section 3, Part 6/Section 3B
Inspection Chamber — Part 9/Section 1
Installation (Electrical), of Buildings — Part 8/
Section 2
Insulated — Part 8/Section 2
Insulation (Electrical) — Part 8/Section 2
Insulation, Basic — Part 8/Section 2
Insulation, Double — Part 8/Section 2
Insulation, Reinforced — Part 8/Section 2
Insulation, Supplementary — Part 8/Section 2
Interceptor — Part 9/Section 1
Interceptor Manhole or Interceptor Chamber — Part 9/
Section 1
Interlocking Cluster — Part 3
Internal Faces of Cluster — Part 3
Internal Reflected Component (IRC) — Part 8/
Section 1
Invert — Part 9/Section 1, Part 10/Section 1
J
Joint — Part 6/Section 3B, Part 6/Section 4
Joist — Part 6/Section 3B
Junction Pipe — Part 9/Section 1
K
Kerb — Part 10/Section 1
Kerb-Stone — Part 10/Section 1
Knot — Part 6/Section 3
Knot Hole — Part 6/Section 3
Lagging — Part 9/Section 1
Laminated Veneer Lumber — Part 6/Section 3
Landing — Part 8/Section 5
Landing Call Push — Part 8/Section 5
Landing Door — Part 8/Section 5
Landing Zone — Part 8/Section 5
Lateral Support — Part 6/Section 4
Leaf— Part 6/Section 4
Ledge or TAND — Part 3
Length oflnternode — Part 6/Section 3B
Levelling Device, Lift Car — Part 8/Section 5
Levelling Device, One-Way Automatic — Part 8/
Section 5
Levelling Device, Two-Way Automatic Non-Maintaining
— Part 8/Section 5
Levelling Device, Two-Way Automatic Maintaining —
Part 8/Section 5
Levelling Devices — Part 8/Section 5
Levelling Zone — Part 8/Section 5
Licensed Plumber — Part 9/Section 1
Lift — Part 3, Part 8/Section 5
An appliance designed to transport persons or materials
between two or more levels in a vertical or substantially
vertical direction by means of a guided car platform.
Lift Car — Part 8/Section 5
Lift Landing — Part 8/Section 5
Lift Machine — Part 8/Section 5
Lift Pit — Part 8/Section 5
Lift Well — Part 8/Section 5
Lift Well Enclosure — Part 8/Section 5
Lifting Beam — Part 8/Section 5
Light Output Ratio (r\) — Part 8/Section 1
Lighting — Part 8/Section 1
Lignin — Part 6/Section 3B
Linked Switch — Part 8/Section 2
Live Knot — Part 6/Section 3
Live or Alive — Part 8/Section 2
Load Bearing Wall — Part 6/Section 4
Loaded Edge Distance — Part 6/Section 3
Loaded End or Compression End Distance — Part 6/
Section 3B
Local Exhaust Ventilation — Part 8/Section 1
Location — Part 6/Section 3
Locations, Industrial — Part 8/Section 2
Locations, Non-Industrial — Part 8/Section 2
Loft — Part 3
Loose Grain (Loosened Grain) — Part 6/Section 3
Loose Knot — Part 6/Section 3
Lumen (lm) — Part 8/Section 1
Luminance (At a Point of a Surface in a Given
Direction) (Brightness) — Part 8/Section 1
Luminous Flux (<()) — Part 8/Section 1
M
Main Soil Pipe (MSP) — Part 9/Section 1
Main Soil Waste Pipe (MSWP) — Part 9/Section 1
Main Ventilating Pipe (MVP) — Part 9/Section 1
Main Waste Pipe (MWP) — Part 9/Section 1
Maintenance Factor (d) — Part 8/Section 1
Make-up Air — Part 8/Section 1
Make-up Ground — Part 6/Section 2
Manhole — Part 9/Section 1
Manhole Chamber — Part 9/Section 1
Mansard — Part 10/Section 2
Marquee Sign — Part 10/Section 2
Masonry — Part 6/Section 4
PART 1 DEFINITIONS
11
Masonry Unit — Part 6/Section 4
Matchet — Part 6/Section 3B
Mats — Part 6/Section 3B
Means of Egress — Part 4
Mechanical Ventilation — Part 8/Section 1
Meridian — Part 8/Section 1
Mezzanine Floor — Part 3
Miniature Circuit Breaker — Part 8/Section 2
Modular Co-ordination — Part 6/Section 7 A, Part 6/
Section 7B
Modular Grid — Part 6/Section 7 A, Part 6/Section 7B
Module — Part 6/Section 7 A, Part 6/Section 7B
Mortise and Tenon — Part 6/Section 3B
Mould — Part 6/Section 3
Mound — Part 10/Section 1
Multimodule — Part 6/Section 7A, Part 6/Section 7B
Multiple Earthed Neutral System — Part 8/Section 2
Multi-Under-Reamed Pile — Part 6/Section 2
N
Native — Part 10/Section 1
Natural Grade — Part 10/Section 1
Natural Ventilation — Part 8/Section 1
Negative Skin Friction — Part 6/Section 2
Net Section — Part 6/Section 3B
Neutral Conductor — Part 8/Section 2
Node — Part 6/Section 3B
Noise — Part 8/Section 4
Noise Exposure Forecast (NEF) — Part 8/Section 4
Noise Rating (NR) — Part 8/Section 4
Noise Reduction Co-efficient (NRC) — Part 8/
Section 4
Non-Selective Collective Automatic Operation —
Part 8/Section 5
Non-Service Laterine — Part 9/Section 1
Normalized Impact Sound Pressure Level L — Part 8/
Section 4
North and South Points — Part 8/Section 1
O
Occupancy or Use Group — Part 2, Part 3, Part 4
The principal occupancy for which a building or a
part of a building is used or intended to be used; for
the purposes of classification of a building according
to occupancy, an occupancy shall be deemed to
include the subsidiary occupancies which are
contingent upon it.
Occupier — Part 2
Octave Band — Part 8/Section 4
^Offset — Part 6/Section 2, Part 9/Section 1
Oil Buffer — Part 8/Section 5
Oil Buffer Stroke — Part 8/Section 5
Open Clusters — Part 3
Open Sign — Part 10/Section 2
Open Space — Part 3
Open Space, Front — Part 3
Open Space , Rear — Part 3
Open Space, Side — Part 3
Operating Device — Part 8/Section 5
Operation — Part 8/Section 5
Operational Construction/Installation — Part 2
Orientation of Buildings — Part 8/Section 1
Outdoor Furniture — Part 10/Section 1
Outer Diameter — Part 6/Section 3B
Outside Location — Part 6/Section 3A, Part 6/
Section 3B
Over Speed Governor — Part 8/Section 5
Overhead Beams — Part 8/Section 5
Owner — Part 2, Part 3, Part 10/Section 2
Person or body having a legal interest in land and/or
building thereon. This includes free holders,
leaseholders or those holding a sub-lease which both
bestows a legal right to occupation and gives rise to
liabilities in respect of safety or building condition.
In case of lease or sub-lease holders, as far as ownership
with respect to the structure is concerned, the structure
of a flat or structure on a plot belongs to the allottee/
lessee till the allotment/lease subsists.
Ozone Depletion Potential (ODP) — Part 8/Section 3
Panel Wall — Part 6/Section 4
Parapet — Part 3, Part 10/Section 2
Parking Space — Part 3
Partition — Part 3
Partition Wall — Part 6/Section 4
Passenger Lift — Part 8/Section 5
Peat — Part 6/Section 2
Percentile Level, L AN T — Part 8/Section 4
Period of Supply — Part 9/Section 1
Peripheral Field — Part 8/Section 1
Permanent Load — Part 6/Section 2
Permissible Stress — Part 6/Section 3, Part 6/
Section 3B
Permit — Part 2
Pile Foundation — Part 6/Section 2
* Definitions are different.
12
NATIONAL BUILDING CODE OF INDIA
Pilot — Part 9/Section 2
Pink Noise — Part 8/Section 4
Pipe System — Part 9/Section 1
Pipe Work — Part 9/Section 1
Pitch Pocket — Part 6/Section 3
Plenum — Part 8/Section 3
Plinth — Part 3
The portion of a structure between the surface of
the surrounding ground and surface of the floor,
immediately above the ground.
Plinth Area — Part 3, Part 4
The built up covered area measured at the floor level
of the basement or of any storey.
Plug — Part 8/Section 2
Plumbing System — Part 9/Section 1
Plumbing — Part 9/Section 1
Point (in Wiring) — Part 8/Section 2
Porch — Part 3
Portable Sign — Part 10/Section 2
Position and/or Direction Indicator — Part 8/Section 5
Positive Ventilation — Part 8/Section 1, Part 8/
Section 3
Potable Water — Part 9/Section 1
Prefabricate — Part 6/Section 7 A, Part 6/Section 7B
Prefabricated Building — Part 6/Section 7A, Part 6/
Section 7B
Premises — Part 9/Section 1
Pressure Regulator — Part 9/Section 2
Pressurization — Part 4
Pressurization Level — Part 4
Principal Rafter — Part 6/Section 3B
Projecting Sign — Part 10/Section 2
Propeller Fan — Part 8/Section 1
Psychrometric Chart — Part 8/Section 3
Psychrometry — Part 8/Section 3
Puff Ventilation — Part 9/Section 1
Pure Tone — Part 8/Section 4
Purge — Part 9/Section 2
Purlins — Part 6/Section 3B
Qualified Installing Agency — Part 9/Section 2
R
Rated Load (Escalator) — Part 8/Section 5
Rated Load — Part 8/Section 5
Rated Speed (Escalator) — Part 8/Section 5
Rated Speed — Part 8/Section 5
Rating Level L Ar , 7. — Part 8/Section 4
Recirculated Air — Part 8/Section 3
Reflected Glare — Part 8/Section 1
Reflection Factor (Reflectance) — Part 8/Section 1
Refrigerant — Part 8/Section 3
Registered Architect, Engineer, Structural Engineer,
Supervisor, Town Planner — Part 2
Regulatory Sign — Part 10/Section 2
Relative Humidity — Part 8/Section 3
Residual Current Circuit Breaker — Part 8/Section 2
Residual Head — Part 9/Section 1
Retiring Cam — Part 8/Section 5
Return Air — Part 8/Section 3
Reveal — Part 8/Section 1
Reverberation Time, T — Part 8/Section 4
Rheostatic Control — Part 8/Section 5
Riser — Part 9/Section 2
Road — Part 2, Part 3
Road Line — Part 2, Part 3
Roof Battens — Part 6/Section 3B
Roof Exits — Part 4
Roof Sign — Part 10/Section 2
Roof Skeleton — Part 6/Section 3B
Room Height — Part 2, Part 3
The vertical distance measured from the finished floor
surface to the finished ceiling surface. Where a finished
ceiling is not provided, the underside of the joists or
beams or tie beams shall determine the upper point of
measurement for determining the head room.
Room Index (fc. ) — Part 8/Section 1
Roping Multiple — Part 8/Section 5
Row Housing/Row Type Building — Part 3
Saddle — Part 9/Section 1
Safety Gear — Part 8/Section 5
Sanctioned Plan — Part 2
Sand — Part 6/Section 2
Sand, Coarse — Part 6/Secjion 2
Sand, Fine — Part 6/Section 2
Sand, Medium — Part 6/Section 2
Sandwich Panels — Part 6/Section 7A, Part 6/
Section 7B
Sandwich, Structural — Part 6/Section 3
Sanitary Appliances — Part 9/Section 1
Sap Stain — Part 6/Section 3
Sapwood — Part 6/Section 3
Scaffold — Part 6/Section 3B
Screen — Part 10/Section 1
PART 1 DEFINITIONS
13
Sediment — Part 10/Section 1
Selective Collective Automatic Operation — Part 8/
Section 5
Self Compacting Concrete — Part 6/Section 7 A, Part 6/
Section 7B
Semi-Detached Building — Part 3
Service — Part 8/Section 2
Service Laterine — Part 9/Section 1
Service Lift {Dumb-Waiter) — Part 8/Section 5
* Service Pipe — Part 9/Section 1, Part 9/Section 2
Service Road — Part 2, Part 3
Service Shut-Off Valve (Isolation Valve) — Part 9/
Section 2
Set-back Line — Part 2, Part 3
A line usually parallel to the plot boundaries and laid
down in each case by the Authority, beyond which
nothing can be constructed towards the site boundaries.
Sewer — Part 9/Section 1
Shade Factor — Part 8/Section 3
Shake — Part 6/Section 3
Shallow Foundation — Part 6/Section 2
Shear Connectors — Part 6/Section 7 A, Part 6/
Section 7B
Shear Wall — Part 6/Section 4
Sheave — Part 8/Section 5
Shrub — Part 10/Section 1
Sick Building Syndrome (SBS) — Part 8/Section 3
Sign — Part 10/Section 2
Sign Area — Part 10/Section 2
Sign Copy — Part 10/Section 2
Sign Face — Part 10/Section 2
Sign Structure — Part 10/Section 2
Signal Operation — Part 8/Section 5
Signs — Part 10/Section 2
Silt — Part 6/Section 2
Single Automatic Operation — Part 8/Section 5
Single-Speed Alternating Current Control — Part 8/
Section 5
Site (Plot) — Part 2, Part 3, Part 4
A parcel (piece) of land enclosed by definite boundaries.
Site, Corner — Part 3
Site, Depth of— Part 3
Site, Double Frontage — Part 3
Site, Interior or Tandem — Part 3
Sky Component (SC) — Part 8/Section 1
Sky Sign — Part 10/Section 2
Slack Rope Switch — Part 8/Section 5
* Definitions are different.
Slenderness Ratio — Part 6/Section 4
Sliver — Part 6/Section 3B
Slop Hopper (Slop Sink) — Part 9/Section 1
Slope of Grain — Part 6/Section 3
Smoke Damper — Part 8/Section 3
Soakaway — Part 9/Section 1
Socket-Outlet — Part 8/Section 2
Soffit (Crown) — Part 9/Section 1
Soft Landscape — Part 10/Section 1
Soft Rock — Part 6/Section 2
Soil Appliances — Part 9/Section 1
Soil Pipe — Part 9/Section 1
Soil Waste — Part 9/Section 1
Soil, Black Cotton — Part 6/Section 2
Soil, Coarse Grained — Part 6/Section 2
Soil, Find Grained — Part 6/Section 2
Solar Load — Part 8/Section 1
Solid-State d.c. Variable Voltage Control — Part 8/
Section 5
Sound — Part 8/Section 4
Sound Exposure Level, L^ — Part 8/Section 4
Sound Knot — Part 6/Section 3
Sound Power — Part 8/Section 4
Sound Power Level (L w ) — Part 8/Section 4
Sound Pressure Level, L — Part 8/Section 4
p
Sound Pressure, p — Part 8/Section 4
Sound Receiver — Part 8/Section 4
Sound Reduction Index, R — Part 8/Section 4
Sound Source — Part 8/Section 4
Spaced Column — Part 6/Section 3
Spectrum — Part 8/Section 4
Speech Interference Level (SIL) — Part 8/Section 4
Split — Part 6/Section 3
Splits — Part 6/Section 3B
Spot Elevation — Part 10/Section 1
Spray-Head System — Part 8/Section 1
Spread Foundation — Part 6/Section 2
Spring Buffer — Part 8/Section 5
Spring Buffer Load Rating — Part 8/Section 5
Spring Buffer Stroke — Part 8/Section 5
Stack Effect — Part 8/Section 1
Stack Pressure — Part 4
Staircover (or Mumty) — Part 3
Standardized Impact Sound Pressure Level, L nT —
Part 8/Section 4
Standardized Level Difference, D aT — Part 8/Section 4
Static Pressure — Part 8/Section 3
Stop Tap — Part 9/Section 1
14
NATIONAL BUILDING CODE OF INDIA
Stop-Cock — Part 9/Section 1
Storage Tank — Part 9/Section 1
Store v — Part 3
The portion of a building included between the surface
of any floor and the surface of the floor next above it,
or if there be no floor above it, then the space between
any floor and the ceiling next above it.
Storey, Topmost — Part 3
Street — Part 2, Part 3
Any means of access, namely, highway, street, lane,
pathway, alley, stairway, passageway, carriageway,
footway, square, place or bridge, whether a
thoroughfare or not, over which the public have a right
of passage or access or have passed and had access
uninterruptedly for a specified period, whether existing
or proposed in any scheme and includes all bunds,
channels, ditches, storm-water drains, culverts,
sidewalks, traffic islands, roadside trees and hedges,
retaining walls, fences, barriers and railings within the
street lines.
Street Furniture — Part 10/Section 1
Street Level or Grade — Part 2, Part 3
The officially established elevation or grade of the
centre line of the street upon which a plot fronts and if
there is no officially established grade, the existing
grade of the street at its mid-point.
Street Line — Part 2, Part 3, Part 10/Section 2
The line defining the side limits of a street.
Structural Element — Part 6/Section 3
Structural Grades — Part 6/Section 3
Structural Purpose Definitions — Part 6/Section 3,
Part 6/Section 3B
Structural Timber — Part 6/Section 3
Structure Borne Noise — Part 8/Section 4
Structure, Permanent — Part 6/Section 3
Structure, Temporary — Part 6/Section 3
Sub-Soil Water — Part 9/Section 1
Sub-Soil Water Drain — Part 9/Section 1
Sub-Zero Temperature Regions — Part 9/Section 1
Supply Air — Part 8/Section 3
Supply and Return Air Grilles and Diffusers — Part 8/
Section 3
Supply Pipe — Part 9/Section 1
Supports — Part 9/Section 1
Surface Cracking — Part 6/Section 3B
Surface Water — Part 9/Section 1
Surface Water Drain — Part 9/Section 1
Suspension Ropes — Part 8/Section 5
Swale — Part 10/Section 1
Switch — Part 8/Section 2
Switch Disconnector Fuse — Part 8/Section 2
Switch Disconnectors — Part 8/Section 2
Switchboard — Part 8/Section 2
Switchgear — Part 8/Section 2
System — Part 6/Section 7 A, Part 6/Section 7B,
Systems of Drainage — Part 9/Section 1
T
Taper — Part 6/Section 3B
Temporary Sign — Part 10/Section 2
Terminal Slow Down Switch — Part 8/Section 5
Terminal Stopping Device Final — Part 8/Section 5
Terminal Stopping Switch Normal — Part 8/Section 5
Termites — Part 6/Section 3
Thermal Energy Storage — Part 8/Section 3
Thermal Transmittance — Part 8/Section 3
Third Octave Band — Part 8/Section 4
Threshold Limit Value (TLV) — Part 8/Section 1
Threshold of Hearing — Part 8/Section 4
Tight Knot — Part 6/Section 3
Tissue — Part 6/Section 3B
To Abut — Part 3
To Erect — Part 2, Part 3
Top Car Clearance — Part 8/Section 5
Top Counterweight Clearance — Part 8/Section 5
Topsoil — Part 10/Section 1
Tot Lot — Part 10/Section 1
Total Headroom — Part 8/Section 5
Total Settlement — Part 6/Section 2
Tower-like Structures — Part 3
Trade Effluent — Part 9/Section 1
Transient Sound — Part 8/Section 4
Transplanting — Part 10/Section 1
Trap — Part 9/Section 1
Travel — Part 8/Section 5
Travel Distance — Part 4
Tree — Part 10/Section 1
Tree Grate — Part 10/Section 1
Tree/Plant Guard — Part 10/Section 1
Tropical Summer Index (TSI) — Part 8/Section 1
Two-Speed Alternating Current Control — Part 8/
Section 5
Types of Walls — Part 6/Section 4
U
Ultimate Load Capacity — Part 6/Section 2
Under-Reamed Pile — Part 6/Section 2
PART 1 DEFINITIONS
15
Unit — Part 6/Section 7 A, Part 6/Section 7B
Unloaded End Distance — Part 6/Section 3B
Unsafe Building — Part 2
Usable Wall Space — Part 8/Section 2
Utilization Factor (Coefficient of Utilizaiton) (|l) —
Part 8/Section 1
Variable Voltage Motor Control (Generator Field
Control) — Part 8/Section 5
Velocity, Capture — Part 8/Section 1
Vent Pipe — Part 9/Section 2
Vent StackNent Pipe — Part 9/Section 1
Vent System — Part 9/Section 1
Ventilation — Part 4, Part 8/Section 1
Venting Fire — Part 4
Verandah — Part 3
Verandah Sign — Part 10/Section 2
Vertical Pipe — Part 9/Section 1
Vibration Isolation — Part 8/Section 4
Visual Field — Part 8/Section 1
Voltage Extra Low — Part 8/Section 2
Voltage Extra High — Part 8/Section 2
Voltage, High — Part 8/Section 2
Voltage, Low — Part 8/Section 2
Voltage, Medium — Part 8/Section 2
Volume to Plot Area Ratio (VPR) — Part 3, Part 4
The ratio of volume of building measured in cubic
metres to the area of the plot measured in square metres
and expressed in metres.
W
Wall Sign — Part 10/Section 2
Wall Thickness — Part 6/Section 3B
Wane — Part 6/Section 3
Warning Pipe — Part 9/Section 1
Warp — Part 6/Section 3
Wash-Out Valve — Part 9/Section 1
Waste Appliance — Part 9/Section 1
Waste Pipe — Part 9/Section 1
Waste-Water (Sullage) — Part 9/Section 1
Water Conditioning — Part 8/Section 3
Water Hardness — Part 8/Section 3
Water Main (Street Main) — Part 9/Section 1
Water Outlet — Part 9/Section 1
Water Seal — Part 9/Section 1
Water Supply System — Part 9/Section 1
Water-Closet (WC) — Part 3
Waterworks — Part 9/Section 1
Wavelength — Part 8/Section 4
Weatherproof— Part 8/Section 2
Weighted Level Difference, D w — Part 8/Section 4
Weighted Normalized Impact Sound Pressure Level,
L nw — Part 8/Section 4
Weighted Sound Reduction Index, R w — Part 8/
Section 4
Weighted Standardized Impact Sound Pressure Level,
i nT , w — Part 8/Section 4
Weighted Standardized Level Difference, D n Tw —
Part 8/Section 4
* Wet Bulb Temperature — Part 8/Section 1, Part 8/
Section 3
Wet Location — Part 6/Section 3, Part 6/Section 3B
Wet Riser — Part 4
White Noise — Part 8/Section 4
Window — Part 3
Window Sign — Part 10/Section 2
Working Plane — Part 8/Section 1
Worm Holes — Part 6/Section 3
Wrinkled and Deformed Surface — Part 6/Section 3B
* Definitions are different.
16
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 2 ADMINISTRATION
BUREAU OF INDIAN STANDARDS
FOREWORD
CO NTE NTS
SECTION 1 GENERAL
1 SCOPE
2 TERMINOLOGY
3 APPLICABILITY OF THE CODE
4 INTERPRETATION
5 ALTERNATIVE MATERIALS, METHODS OF DESIGN AND
CONSTRUCTION, AND TESTS
SECTION 2 ORGANIZATION AND ENFORCEMENT
6 DEPARTMENT OF BUILDINGS
7 POWER AND DUTIES OF TEAM OF BUILDING OFFICIALS
8 BOARD OF APPEALS
9 VIOLATIONS AND PENALTIES
10 POWER TO MAKE RULES
5
5
6
7
7
9
9
9
SECTION 3 PERMIT AND INSPECTION
1 1 DEVELOPMENT/BUILDING PERMIT
12 APPLICATION FOR DEVELOPMENT/BUILDING PERMIT
13 RESPONSIBILITIES AND DUTIES OF THE OWNER
14 INSPECTION, OCCUPANCY PERMIT AND POST- OCCUPANCY
INSPECTION
15 UNSAFE BUILDING
16 DEMOLITION OF BUILDING
17 VALIDITY
18 ARCHITECTURAL CONTROL
ANNEX A GUIDE FOR THE QUALIFICATIONS AND COMPETENCE OF
PROFESSIONALS
ANNEX B FORM FOR FIRST APPLICATION TO DEVELOP, ERECT,
RE-ERECT OR TO MAKE ALTERATION IN ANY PLACE IN A
BUILDING
ANNEX C FORM FOR CERTIFICATE FOR STRUCTURAL DESIGN
SUFFICIENCY
ANNEX D FORM FOR SUPERVISION
ANNEX E FORM FOR SANCTION OR REFUSAL OF DEVELOPMENT/
BUILDING PERMIT
ANNEX F FORM FOR NOTICE FOR COMMENCEMENT
ANNEX G FORM FOR CERTIFICATE FOR EXECUTION OF WORK AS
PER STRUCTURAL SAFETY REQUIREMENTS
ANNEX H FORM FOR COMPLETION CERTIFICATE
ANNEX J FORM FOR OCCUPANCY PERMIT
9
10
15
15
16
16
17
17
18
20
21
21
22
22
23
23
24
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
A need for codifying and unifying administrative provisions in different development control rules and building
byelaws had been felt, particularly in regard to the applicability of the Code, desirable qualifications for the enforcing
Authority and the representative of the owner and responsibilities and duties of the Authority and the owner.
It is expected that the town and country planning department will co-ordinate the administrative provisions of
this Part and the same given in the State Town and Country Planning Acts.
This Part recommends the setting up of a 'Board of Appeal'. The 'Board of Appeal' gives the owner/architect/
engineer an opportunity to defend the schemes which are based on conventional or new methods of design and
construction or using new materials, which have been otherwise rejected by the Authority.
This Part also emphasizes the need for setting up an Arts Commission for metropolitan areas to safeguard existing
aesthetics in the event of new schemes proposed for buildings of public importance or buildings coming up in an
important area near historic/monumental buildings. The Commission can assist the civic authorities in reviewing
plans for development from the stand point of assuring good taste and regard for often threatened natural beauties.
The Commission can serve as a means whereby by the government and public bodies and individuals could get
advice on artistic questions in connection with building schemes.
The first version of this Part was brought out in 1970, which was subsequently revised in 1983. As a result of
implementing 1970 version of this Part in rewriting building byelaws and development control rules of some
municipal corporations and municipalities, some useful suggestions were emerged. These were incorporated in
the first revision to the extent possible. The significant changes in 1983 version of this Part included the new
administrative provisions related to development control rules, additional information to be furnished/indicated
in the building plan for multi-storeyed and special buildings and modified provisions regarding submission of
building plans by Government Departments to the Authority.
In this second revision, number of modifications have been incorporated based on the experience gained over the
years specially in view of different techno-administrative and techno-legal regime encountered in various situations
faced. Specially the provisions of this Part have been thoroughly reviewed in the context of the natural calamities
faced by the country, such as the devastating earthquake in Gujarat in the year 2001, and provisions have been
accordingly modified to further ensure structural adequacy of the buildings. In this context, structural design of
buildings in accordance with the provisions of the Code and construction and supervision thereof by competent
professionals to ensure structural safety have been given due importance in this revision. Other significant
modifications incorporated include:
a) Modifications in the definitions of certain terms;
b) Inclusion of the concept of team of building officials;
c) Inclusion of provision of single window approach for permit for all services;
d) Inclusion of provisions regarding computerization of approval processes for building permits;
e) Inclusion of provision to certify safety of buildings against natural disaster by engineer/structural engineer
and owner;
f) Inclusion of provision of two stage permit for high rise residential buildings and special buildings;
g) Provisions regarding inspection of completed and occupied building by the Authority from safety point
of view have been made comprehensive;
h) Inclusion of provision empowering engineers/architects for sanctioning plans of residential buildings
up to 500 m 2 ;
j) Provisions for architectural control to effectively take care of the urban aesthetics, have been modified;
and
k) Inclusion of landscape architect and urban designer among the registered professionals for the concerned
applicable works.
PART 2 ADMINISTRATION 3
The Sectional Committee responsible for revision of the Code has examined the use of the words 'surveyor/
building surveyor/supervisor', etc under various building bye-laws with varying qualifications in different states
It has been decided not to use the generic word 'surveyor' or such other words. The Sectional Committee has, on
the other hand recommended association of various professionals for various job responsibilities depending
upon their qualifications/competence.
Also, it is noted that the words 'licencing/licensed, etc' are in use by local bodies in different states. The Sectional
Committee, however, decided for use of words 'registration/registered, etc' for the same, which may now be
adopted uniformly. The registration requirements of professionals are given in Annex A.
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 2 ADMINISTRATION
SECTION 1 GENERAL
1 SCOPE
This Part covers the administrative aspects of the Code,
such as applicability of the Code, organization of
building department for enforcement of the Code,
procedure for obtaining development and building
permits, and responsibility of the owner.
NOTE — This Code is called the National Building Code of
India, hereinafter referred to as 'the Code' .
2 TERMINOLOGY
2.0 For the purpose of this part, the following
definitions shall apply.
2.1 Accessory Use — Any use of the premises
subordinate to the principal use and customarily
incidental to the principal use.
2.2 Alteration — A change from one type of
occupancy to another, or a structural change, such as
an addition to the area or height, or the removal of part
of a building, or any change to the structure, such as
the construction of, cutting into or removal of any wall,
partition, column, beam, joist, floor or other support,
or a change to or closing of any required means of
ingress or egress or a change to the fixtures or
equipment.
2.3 Approved — Approved by the Authority having
jurisdiction.
2.4 Authority Having Jurisdiction — The Authority
which has been created by a statute and which, for the
purpose of administering the Code/Part, may authorize
a committee or an official or an agency to act on its
behalf; hereinafter called the 'Authority'.
2.5 Building — Any structure for whatsoever purpose
and of whatsoever materials constructed and every part
thereof whether used as human habitation or not and
includes foundation, plinth, walls, floors, roofs,
chimneys, plumbing and building services, fixed
platforms, verandah, balcony, cornice or projection, part
of a building or anything affixed thereto or any wall
enclosing or intended to enclose any land or space
and signs and outdoor display structures. Tents/
SHAMIANAHS, tarpaulin shelters, etc, erected for
temporary and ceremonial occasions with the permission
of the Authority shall not be considered as building.
2.6 Building, Height of — The vertical distance
measured, in the case of flat roofs from the average
level of the ground around and contiguous to the
building or as decided by the Authority to the terrace
of last livable floor of the building adjacent to the
external walls; and in the case of pitched roofs, up to
the point where the external surface of the outer wall
intersects the finished surface of the sloping roof, and
in the case of gables facing the road, the midpoint
between the eaves level and the ridge. Architectural
features serving no other function except that of
decoration shall be excluded for the purpose of
measuring heights.
2.7 Building Line — The line up to which the plinth
of a building adjoining a street or an extension of a
street or on a future street may lawfully extend. It
includes the lines prescribed, if any, in any scheme.
The building line may change from time-to-time as
decided by the Authority.
2.8 Conversion — The change of occupancy or
premises to any occupancy or use requiring additional
occupancy permit.
2.9 Development — 'Development' with grammatical
variations means the carrying out of building,
engineering, mining or other operations in, or over, or
under land or water, or in the use of any building or
land, and includes redevelopment and layout and
subdivision of any land; and 'to develop' shall be
construed accordingly.
2.10 Drain — A conduit or channel for the carriage
of storm water, sewage, waste water or other water-
borne wastes in a building drainage system.
2.11 Drainage — The removal of any liquid by a
system constructed for the purpose.
2.12 Occupancy or Use Group — The principal
occupancy for which a building or a part of a building
is used or intended to be used; for the purposes of
classification of a building according to occupancy,
an occupancy shall be deemed to include the subsidiary
occupancies which are contingent upon it.
2.13 Occupier — Occupier includes any person for
the time being, paying or liable to pay rent or any
portion of rent of the building in respect of which the
ward is used, or compensation or premium on account
of the occupation of such building and also a rent-free
tenant, but does not include a lodger, and the words
'occupy' and 'occupation' do not refer to the lodger.
An owner living in or otherwise using his own building
shall be deemed to be the occupier thereof.
2.14 Operational Construction/Installation — A
construction/installation put up by Government
Departments for operational purposes (see 12.1.1.1).
PART 2 ADMINISTRATION
2.15 Owner — Person or body having a legal interest
in land and/or building thereon. This includes free
holders, leaseholders or those holding a sub-lease
which both bestows a legal right to occupation and
gives rise to liabilities in respect of safety or building
condition.
In case of lease or sub-lease holders, as far as ownership
with respect to the structure is concerned, the structure
of a flat or structure on a plot belongs to the allottee/
lessee till the allotment/lease subsists.
2.16 Permit — A permission or authorization in
writing by the Authority to carry out work regulated
by the Code.
2.17 Registered Architect, Engineer, Structural
Engineer, Supervisor, Town Planner, Landscape
Architect, Urban Designer — A qualified architect,
engineer, structural engineer, supervisor, town
planner, landscape architect or urban designer who
has been registered by the Authority or by the body
governing such profession and constituted under a
statute, as may be applicable. The registration
requirements of these professionals shall be as given
in Annex A.
NOTES
1 Unless specified otherwise, the word 'engineer* shall mean
'civil engineer' or 'architectural engineer'.
2 The word 'licencing/licensed, etc' if used by the Authority
in the above context shall be deemed to mean 'registration/
registered', etc.
2.18 Road — See 2.25.
2.19 Road Line — See 2.27.
2.20 Room Height — The vertical distance measured
from the finished floor surface to the finished ceiling
surface. Where a finished ceiling is not provided, the
underside of the joists or beams or tie beams shall
determine the upper point of measurement for
determining the head room.
2.21 Sanctioned Plan — The set of plans and
specifications submitted in connection with a building
or development and duly approved and sanctioned by
the Authority.
2.22 Service Road — A road/lane provided at the rear
or side of a plot for service purposes.
2.23 Set-back Line — A line usually parallel to the
plot boundaries and laid down in each case by the
Authority, beyond which nothing can be constructed
towards the site boundaries.
2.24 Site (Plot) — A parcel (piece) of land enclosed
by definite boundaries.
2.25 Street — Any means of access, namely, highway,
street,' lane, pathway, alley, stairway, passageway,
carriageway, footway, square, place or bridge, whether
a thoroughfare or not, over which the public have a
right of passage or access or have passed and had access
uninterruptedly for a specified period, whether existing
or proposed in any scheme and includes all bunds,
channels, ditches, storm-water drains, culverts,
sidewalks, traffic islands, roadside trees and hedges,
retaining walls, fences, barriers and railings within the
street lines.
2.26 Street Level or Grade — The officially
established elevation or grade of the centre line of the
street upon which a plot fronts and if there is no
officially established grade, the existing grade of the
street at its mid-point.
2.27 Street Line — The line defining the side limits
of a street.
2.28 To Erect — To erect a building means:
a) to erect a new building on any site whether
previously built upon or not;
b) to re-erect any building of which portions
above the plinth level have been pulled down,
burnt or destroyed.
2.29 Unsafe Building — Buildings which are
structurally and constructionally unsafe or insanitary
or not provided with adequate means of egress or
which constitute a fire hazard or are otherwise
dangerous to human life or which in relation to
existing use constitute a hazard to safety or health or
public welfare, by reason of inadequate maintenance,
dilapidation or abandonment.
3 APPLICABILITY OF THE CODE
3.1 All Parts of the Code and their sections shall apply
to all buildings described in 3.2 to 3.8, as may be
applicable.
3.2 Where a building is erected, the Code applies to
the design and construction of the building.
3.3 Where the whole or any part of the building is
removed, the Code applies to all parts of the building
whether removed or not.
3.4 Where the whole or any part of the building is
demolished, the Code applies to any remaining part
and to the work involved in demolition.
3.5 Where a building is altered {see 12.4 and 12.4.1),
the Code applies to the whole building whether existing
or new except that the Code applies only to part if that
part is completely self-contained with respect to
facilities and safety measures required by the Code.
3.6 Where the occupancy of a building is changed,
the Code applies to all parts of the building affected
by the change.
NATIONAL BUILDING CODE OF INDIA
3.7 Where development of land is undertaken the Code
applies to the entire development of land.
3.8 Existing Buildings/Development
Nothing in the Code shall require the removal,
alteration or abandonment, nor prevent continuance
of the use or occupancy of an existing building/
development, unless in the opinion of the Authority,
such building/development constitutes a hazard to the
safety of the adjacent property or the occupants of the
building itself.
4 INTERPRETATION
4*1 The heading which appears at the beginning of a
clause or sub-clause of the Code shall be deemed to be
a part of such clause or sub-clause respectively.
4.2 The use of present tense includes the future tense,
the masculine gender includes the feminine and the
neuter, the singular number includes the plural and the
plural includes the singular. The word 'person' includes
a corporation as well as an individual; writing includes
printing and typing and 'signature* includes thumb
impression made by a person who cannot write if his
name is written near to such thumb impression.
5 ALTERNATIVE MATERIALS, METHODS OF
DESIGN AND CONSTRUCTION, AND TESTS
5.1 The provisions of the Code are not intended to
prevent the use of any material or method of design or
construction not specifically prescribed by the Code,
provided any such alternative has been approved,
5.2 The Authority may approve any such alternative
provided it is found that the proposed alternative is
satisfactory and conforms to the provisions of relevant
parts regarding material, design and construction and
that material, method, or work offered is, for the purpose
intended, at least equivalent to that prescribed in the
Code in quality, strength, compatibility, effectiveness,
fire and water resistance, durability and safety.
5.3 Tests
Whenever there is insufficient evidence of compliance
with the provisions of the Code or evidence that any
material or method of design or construction does not
conform to the requirements of the Code or in order to
substantiate claims for alternative materials, design or
methods of construction not specifically prescribed in
the Code, the Authority may require tests sufficiently
in advance as proof of compliance. These tests shall
be made by an approved agency at the expense of the
owner.
5.3.1 Test methods shall be specified by the Code for
the materials or design or construction in question. If
there are no appropriate test methods specified in the
Code, the Authority shall determine the test procedure.
For methods of test for building materials, reference
may be made to Part 5 Building Materials.
5.3.2 Copies of the results of all such tests shall be
retained by the Authority for a period of not less than
two years after the acceptance of the alternative material.
SECTION 2 ORGANIZATION AND
ENFORCEMENT
6 DEPARTMENT OF BUILDINGS
6.1 The department of buildings shall be created by
the Authority and a team of building officials shall be
appointed to carry out work of such department.
6.2 Appointment of Team of Building Officials
The team of building officials shall be appointed by
the Authority. The team shall comprise officials drawn
from concerned disciplines such as engineer, architect,
town planner, landscape architect and urban designer
as may be decided by the Authority. For scrutiny of
layout plans of plots of one hectare and above in metro
cities and two hectares and above in other places, town
planner, shall be part of the team of building officials.
For plots of five hectares and above, landscape architect
shall also be part of the team. An urban designer shall
also be required to be the part of team of building
officials for examining proposals on integrated urban
design and development for residential/business/
institutional and assembly building.
NOTE — Metro cities are cities with population more than
1 000 000.
6.3 Organization
In the department of buildings, such number of officers,
technical assistants, inspectors and other employees
shall be appointed to assist the team of building officials
as shall be necessary for the administration of the Code
and as authorized by the Authority.
6.4 Delegation of Powers
The Authority may designate one of the building
officials who shall exercise all the powers of the team
of building officials. The work of the team of building
officials may be outsourced to competent professional/
agency/group as may be deemed necessary.
6.5 Qualification of Building Officials
The qualification of building officials scrutinizing the
plans and carrying out inspection of buildings shall
not in any case be less than those prescribed in
Annex A.
6.5.1 In small local bodies having insufficient
resources to appoint such officials with the above
PART 2 ADMINISTRATION
qualifications, two or three such bodies contiguously
located could join together and share the services of
one team of building officials.
6.6 Qualifications of Assistant
No person shall be appointed as Assistant unless he
has got the qualifications prescribed in Annex A for a
registered Supervisor.
6.7 Restriction on Employees
No official or employee connected with the department
of buildings except one whose only connection is that
of a member of the Board of Appeals, established
under 8 shall be engaged directly or indirectly in a work
connected with the furnishing of labour, materials
or appliances for the construction, alteration or
maintenance of a building, or the preparation of plans
or of specifications thereof unless he is the owner of
building; nor shall such official or employee engage
in any work which conflicts with his official duties or
with the interests of the Department.
6.8 Records
Proper records of all applications received, permits and
orders issued, inspections made shall be kept and copies
of all papers and documents connected with the
administration of its duties shall be retained and all
such records shall be open to public inspection at all
appropriate times.
7 POWER AND DUTIES OF TEAM OF BUILDING
OFFICIALS
7.0 The team of building officials shall enforce all the
provisions of the Code and shall act on any question
relative to the mode or manner of construction and the
materials to be used in the erection, addition, alteration,
repair, removal, demolition, installation of service
equipment and the location, use, occupancy and
maintenance of all buildings except as may otherwise
be specifically provided.
7.1 Application and Permits
The team of building officials shall receive all
applications and issue permits (see 12.10) for the
erection and alteration of buildings and examine the
premises for which such permits have been issued and
enforce compliance with the Code.
7.2 Building Notices and Orders
The team of building officials shall issue all necessary
notices or orders to remove illegal or unsafe conditions,
to require the necessary safeguards during construction,
to require adequate exit facilities in existing buildings
and to ensure compliance with all the requirements of
safety, health and general welfare of the public as
included in the Code.
7.3 Right of Entry
Upon presentation of proper credentials and with
advance notice, the team of building officials or its
duly authorized representative may enter at any
reasonable time any building or premises to perform
any duty imposed upon him by the Code.
7.4 Inspection
The team of building officials shall make all the
required inspections or it may accept reports of
inspections of authoritative and recognized services
or individuals; and all reports of inspections shall be
in writing and certified by a responsible officer of such
authoritative service or by the responsible individual
or engage any such expert opinion as he may deem
necessary to report upon unusual technical issues that
may arise, subject to the approval of the Authority.
7.5 Construction Not According to Plan
Should the team of building officials determine at any
stage that the construction is not proceeding according
to the sanctioned plan or is in violation of any of the
provisions of the Code, or any other applicable Code
Regulation, Act or Byelaw, it shall notify the owner,
and all further construction shall be stayed until
correction has been effected and approved.
7.5.1 Should the owner fail to comply with the
requirements at any stage of construction, the Authority
shall issue a notice to the owner asking explanation
for non-compliance. If the owner fails to comply within
14 days from the date of receiving the notice, the
Authority shall be empowered to cancel the building
permit issued and shall cause notice of such
cancellation to be securely pasted upon the said
construction, if the owner is not traceable at his address
given in the notice. Pasting of such a notice shall be
considered sufficient notification of cancellation to the
owner thereof. No further work shall be undertaken or
permitted upon such construction until a valid building
permit thereafter has been issued. If the owner, in
violation of the notice for cancellation, continues the
construction, the Authority may take all necessary
means to stop such work and further appropriate actions
including demolitions. The owner shall, however, have
right to appeal against cancellation of permit, to the
board of appeal, within a stipulated period, as may be
decided by the Authority.
7.6 Modification
Wherever practical difficulties are involved in carrying
out any provision of the Code, the team of building
officials may vary or modify such provisions upon
application of the owner or his representative provided
the spirit and intent of the Code shall be observed and
public welfare and safety be assured. The application
8
NATIONAL BUILDING CODE OF INDIA
for modification and the final decision of the team of
building officials shall be in writing and shall be
officially recorded with the application for the permit
in the permanent records of the Department of Building
Inspection.
7.7 Occupancy Violations
Wherever any building is being used contrary to
provisions of the Code, the team of building officials
may order such use discontinued and the building or
portion thereof, vacated by the notice served on any
person, causing such use to be discontinued. Such
person shall discontinue the use within 10 days after
receipt of such notice or make the building or portion
thereof, comply with the requirements of the Code.
8 BOARD OF APPEALS
In order to determine the suitability of alternative
materials or methods of design or construction and to
provide for reasonable interpretation of the provisions
of the Code or in the matter of dispute relating to an
ongoing construction vis-a-vis the sanctioned plan, a
Board of Appeals consisting of members who are
qualified by experience and training and to pass
judgement upon matters pertaining to building
construction, shall be appointed by the Authority. A
representative of the team of building officials shall
be an ex-officio member and shall act as secretary to
the Board. The Board shall adopt reasonable rules and
regulations for conducting its investigations and shall
render all decisions and findings in writing to the team
of building officials with a duplicate copy to the
appellant and may recommend such modifications as
are necessary.
9 VIOLATIONS AND PENALTIES
9.1 Offences and Penalties
9.1.1 Any person who contravenes any of the
provisions of the Code or any requirements of
obligations imposed on him by virtue of the Code, or
who interferes with or obstructs any person in the
discharge of his duties, shall be guilty of an offence
and the Authority shall levy suitable penalty or take
other actions as per the Code (see also 7.5 and 15).
NOTE — The penalty may be in the form of collection of
arrears of tax.
9.1.2 The buildings/developments violating any
applicable statutory rules shall be demolished/brought
within the limits as prescribed in such rules at the
expense of the owner. The buildings coming up in the
vicinity of an aerodrome in violation of the height
restriction laid down by the Directorate General of Civil
Aviation shall be accordingly demolished/brought
within the limits prescribed by DGCA rules.
9.1.3 The registered architect, engineer, structural
engineer, supervisor, town planner, landscape architect,
urban designer and utility service engineer (see
Annex A) responsible for the services rendered for
supervision of the construction/development and for the
completion certificate; in the event of violation of the
provisions of the Code, shall be liable to penalties as
prescribed by the Authority including cancellation of
registration done by it or make such recommendation
to the statutory body governing such profession.
9.2 Further Obligation of Offender
The conviction of any person for an offence under the
provision of 9.1 shall not relieve him from the duty of
carrying out the requirements or obligations imposed
on him by virtue of the provisions of the Code; and if
such requirements or obligations are not complied with
in accordance with an order made under provisions
of 9.1, the Authority under the provisions of the Code
may, if necessary and advisable, enter upon the
premises in respect of which a conviction has been
made and carry out at the expense of the convicted
person, the requirements or obligations referred to in
the said order and the expense, if not paid on demand,
may be recovered with cost in a court.
9.3 Conviction No Bar to Further Prosecution
The conviction of any person under the provisions of
this part for failing to comply with any of the said
requirements or obligations shall not operate as a bar
to further prosecution under this part for any
subsequent failure on the part of such person to comply.
10 POWER TO MAKE RULES
The Authority may make rules for carrying out the
provisions and intentions of the Code provided that
any rule shall not be in direct/indirect conflict or
nullify/dilute any of the provisions of the Code.
SECTION 3 PERMIT AND INSPECTION
11 DEVELOPMENT/BUHJ)ING PERMIT
11.1 Permit Required
No person shall carry out any development, erect, re-
erect or make alterations or demolish any building or
cause the same to be done without first obtaining a
separate permit for each such development/building
from the Authority. No permits shall, however, be
required for works referred to in 12.1.1.1 and 12.4.1.
11.1.1 The development/building permit shall take
into cognizance the provisions under the relevant Town
Planning Act/Development Act/Municipal Act/any
other applicable statutes for layout, building plans,
water supply, sewerage, drainage, electrification, etc,
as provided in the said Act/statute. Also, if so directed
PART 2 ADMINISTRATION
by the Authority, the permit shall take care of the need
for landscape development plan incorporating rain-
water harvesting proposals in the layout and building
plans.
11.1.2 Specific approvals shall be obtained from
Civil Aviation Authorities, Fire Services Department
(in case the building proposed is 15 m and above),
Pollution Control Board, designated authorities under
Factories Act/Cinema Regulation Act, Urban Arts
Commission, designated Coastal Regulation Zone
Authority, Archeological Survey of India, Heritage
Committee and any such other authority as may be
applicable.
11.1.3 In order to facilitate clearance from above
bodies with the concept of single window clearance
approach and thereby final approval by the Authority
within the stipulated time frame, the Authority may
constitute a Development/Building Permit Approval
Committee consisting of representative of the team of
building officials, representatives of all bodies/
organizations from whom clearance for development/
building permit clearance is required.
Recommendations from such Committee shall be
summarily utilized by the team of building officials
in sanctioning process. The Committee may meet
once in 15/30 days depending upon the work load.
The first response/invalid notice/non-compliance
intimation shall be issued by the Authority to the
owner within 30 days of submission of the plans to
the Authority.
11.1.4 The Authority shall permit a registered
architect/engineer to approve the building proposals
including plans, and certify completion of building for
issue of related regulatory building permits and
occupancy certificate for residential buildings designed
by self or otherwise, on plot size up to 500 m 2 . The
responsibility of compliance with respect to provisions
of Code shall rest with the registered architect/engineer.
However, the plans shall be required to be submitted
to the Authority for information and record.
NOTE — Where the experience clearly shows that satisfactory
building permit activities are being carried out through the
above empowerment of professionals, the Authority may
extend such provision for larger areas and other building
occupancies.
11.2 Pre-Code Development/Building Permit
If any development/building, permit for which had
been issued before the commencement of the Code, is
not wholly completed within a period of three years
from the date of such permit, the said permission shall
be deemed to have lapsed and fresh permit shall be
necessary to proceed further with the work in
accordance with the provisions of the Code.
12 APPLICATION FOR DEVELOPMENT/
BUILDING PERMIT
12,1 Notice
Every owner who intends to develop, erect, re-erect or
make alterations in any place in a building shall give
notice in writing to the Authority of his said intention
in the prescribed form (see Annex B) and such notice
shall be accompanied by plans and statements in
triplicate as required under 12.2 and 12.3 except for
special buildings (high rise, non-residential) where
additional copies may be submitted as desired by the
Authority. The Authority shall permit submission of
plans/documents in electronic form in addition to hard
copy. The Authority should also progressively
computerize the approval process.
12.1.1 Regarding submission of plans by Government
Departments, the procedure shall be as given
in 12.1.1.1 and 12.1.1.2
12.1.1.1 The operational construction/installation of
the Government, whether temporary or permanent,
which is essential for the operation, maintenance,
development or execution of any of the following
services may be exempted from the point of view of
the byelaws:
a) Railways;
b) National highways;
c) National waterways;
d) Major ports;
e) Airways and aerodromes;
f) Posts and telegraphs, telephones, wireless,
broadcasting, and other like forms of
communications ;
g) Regional grid for electricity;
h) Defence; and
j) Any other service which the Central/State
Government may, if it is of opinion that the
operation, maintenance, development of
execution of such service is essential to the
life of the community, by notification, declare
to be a service for the purpose of this clause.
In case of construction/installation where no approvals
are required, the concerned agencies which are
exempted from seeking approval shall submit the
drawings/plans/details for information and records of
the Authority before construction/installation.
12.1.1.2 However, the following construction of the
Government departments do not come under the
purview of operational construction for the purpose of
exemption under 12.1.1.1:
a) New residential building (other than gate
lodges, quarters for limited essential operational
10
NATIONAL BUILDING CODE OF INDIA
b)
staff and the like), roads and drains in railway
colonies, hospitals, clubs, institutes and
schools, in the case of railways; and
A new building, new construction or new
installation or any extension thereof in the
case of any other services.
12.2 Information Accompanying Notice
The notice shall be accompanied by the key plan, site
plan, building plan, services plans, specifications
structural sufficiency certificate and certificate of
supervision as prescribed in 12.2.2 to 12.2.8.
12.2.1 Sizes of Drawing Sheets and Recommended
Notation for Colouring Plans
12.2.1.1 The size of drawing sheets shall be any of
those specified in Table 1.
Table 1 Drawing Sheet Sizes
(Clause 12.2.1.1)
SI No.
Designation
Trimmed Size
mm
(1)
(2)
(3)
i)
AO
841 x 1 189
ii)
Al
594 x 841
iii)
A2
420 x 594
iv)
A3
297 x 420
v)
A4
210 x 297
vi)
A5
148 x 210
12.2.1.2 The plans shall be coloured as specified in
Table 2.
12.2.2 Key Plan
A key plan drawn to a scale of not less than 1 in 10 000
shall be submitted along with the application for a
development/building permit showing the boundary
locations of the site with respect to neighbourhood
landmarks. The minimum dimension of the key plan
shall be not less than 75 mm.
12.2.3 Site Plan
The site plan sent with an application for permit shall
be drawn to a scale of not less than 1 in 500 for a site
up to one hectare and not less than 1 in 1 000 for a site
more than one hectare and shall show:
a) the boundaries of the site and of any contiguous
land belonging to the owner thereof;
b) the position of the site in relation to
neighbouring street;
c) the name of the streets in which the building
is proposed to be situated, if any;
d) all existing buildings standing on, over or
under the site including service lines;
e) the position of the building and of all other
buildings (if any) which the applicant intends
to erect upon his contiguous land referred to
in (a) in relation to:
Table 2 Colouring of Plans
(Clause 12.2.1.2)
SI
Item
Site Plan
_-* —
Building Plan
No.
• — '
~-»
s~
^
White Plan
Blue Print
Ammonia Print
White Plan
Blue Print
Ammonia Print
(1)
(2)
(3)
(4)
(5)
(6)
(7)-
(8)
i)
Plot lines
Thick black
Thick black
Thick black
Thick black
Thick black
Thick black
ii)
Existing street
Green
Green
Green
—
—
—
iii)
Future street, if any
Green dotted
Green dotted
Green dotted
—
—
—
iv)
Permissible building
Thick dotted
Thick dotted
Thick dotted
—
—
—
lines
black
black
black
v)
Open spaces
No colour
No colour
No colour
No colour
No colour
No colour
vi)
Existing work
Black (outline)
White
Blue
Black
White
Blue
vii)
Work proposed to be
demolished
Yellow hatched
Yellow hatched
Yellow hatched
Yellow hatched
Yellow hatched
Yellow hatched
viii) Proposed work
Red rilled in
Red
Red
Red
Red
Red
(see Note 1)
ix)
Drainage and sewerage
work
Red dotted
Red dotted
Red dotted
Red dotted
Red dotted
Red dotted
x)
Water supply work
Black dotted
Black dotted
Black dotted
Black dotted
Black dotted
Black dotted
thin
thin
thin
thin
thin
-thin
NOTES
1 For entirely new construction this need not be done; for extension of an existing work this shall apply.
2 For land development, subdivision, layout, suitable colouring notations shall be used which shall be indexed.
PART 2 ADMINISTRATION
11
1) the boundaries of the site and in case
where the site has been partitioned, the
boundaries of the portion owned by the
applicant and also of the portions owned
by others;
2) all adjacent street, buildings (with
number of storeys and height) and
premises within a distance of 12 m of the
site and of the contiguous land (if any)
referred to in (a); and
3) if there is no street within a distance of
12 m of the site, the nearest existing
street;
f) the means of access from the street to the
building, and to all other buildings (if any)
which the applicant intends to erect upon his
contiguous land referred to in (a);
g) space to be left about the building to secure a
free circulation of air, admission of light and
access for scavenging purposes;
h) the width of the street (if any) in front and of
the street (if any) at the side or near the
buildings;
j ) the direction of north point relative to the plan
of the buildings;
k) any physical features, such as wells, drains,
etc; and
m) such other particulars as may be prescribed
by the Authority.
12.2.4 Sub -Division/Layout Plan
In the case of development work, the notice shall be
accompanied by the sub-division/layout plan which
shall be drawn on a scale of not less than 1 : 500
containing the following:
a) Scale used and north point;
b) The location of all proposed and existing
roads with their existing/proposed/prescribed
widths within the land;
c) Dimensions of plot along with building lines
showing the setbacks with dimensions within
each plot;
d) The location of drains, sewers, public facilities
and services, and electrical lines, etc;
e) Table indicating size, area and use of all the
plots in the sub-division/layout plan;
f) A statement indicating the total area of the
site, area utilized under roads, open spaces
for parks, playgrounds, recreation spaces for
parks, playgrounds, recreation spaces and
development plan reservations, schools,
shopping and other public places alongwith
their percentage with reference to the total
area of the site proposed to be subdivided;
and
g) In case of plots which are subdivided in built-
up areas in addition to the above, the means
of access to the sub-division from existing
streets.
12.2.5 Building Plan and Details
The plan of the buildings and elevations and sections
accompanying the notice shall be drawn to a scale of
1 : 100. The plans and details shall:
a) include floor plans of all floors together with
the covered area clearly indicating the size
and spacings of all framing members and sizes
of rooms and the position of staircases, ramps
and liftwells;
b) show the use or occupancy of all parts of the
buildings;
c) show exact location of essential services, for
example, WC, sink, bath and the like;
d) include at least one elevation from the front
showing height of building and rooms and
also the height of parapet;
e) include at least one section through the
staircase;
f) include the structural arrangements with
appropriate sections showing type/
arrangement of footings, foundations,
basement walls; structural load bearing walls,
columns and beams, and shear walls; and
arrangement/spacing of framing members,
floor slabs and roof slabs with the material
used for the same;
g) show all street elevations;
h) give dimensions of the projected portions
beyond the permissible building line;
j) include terrace plan indicating the drainage
and the slope of the roof; and
k) give indications of the north point relative to
the plan.
NOTE — The requirement of 1 : 100 is permitted to
be flexible for specific details needed for further
illustration; andJlso for drawings for these in electronic
form.
12.2.5.1 Building plan for multi-stor eyed/ special
buildings
For all multi-storeyed buildings which are 15 m or more
in height and for special buildings like educational,
assembly, institutional, industrial, storage and
hazardous and mixed occupancies with any of the
aforesaid occupancies having covered area more than
500 m 2 , the building sanction shall be done in two
stages.
12
NATIONAL BUILDING CODE OF INDIA
Stage 1: First stage for planning clearance
The following additional information shall be
furnished/indicated in the building plan in addition to
the items given in 12.2.5 as applicable:
a) Access to fire appliances/vehicles with details
of vehicular turning circle and clear motorable
accessway around the building;
b) Size (width) of main and alternative staircases
along with balcony approach, corridor,
ventilated lobby approach;
c) Location and details of lift enclosures;
d) Location and size of fire lift;
e) Smoke stop lobby/door, where provided;
f) Refuse chutes, refuse chamber, service duct,
etc;
g) Vehicular parking spaces;
h) Refuse area, if any;
j) Details of building services — Air-conditioning
system with position of fire dampers,
mechanical ventilation system, electrical
services, boilers, gas pipes, etc;
k) Details of exits including provision of ramps,
etc, for hospitals and special risks;
m) Location of generator, transformer and
switchgear room;
n) Smoke exhauster system, if any;
p) Details of fire alarm system network;
q) Location of centralized control, connecting
all fire alarm systems, built-in-fire protection
arrangements and public address system,
etc;
r) Location and dimensions of static water
storage tank and pump room along with fire
service inlets for mobile pump and water
storage tank;
s) Location and details of fixed fire protection
installations, such as, sprinklers, wet risers,
hose-reels, drenchers, etc; and
t) Location and details of first-aid fire fighting
equipments/installations.
Stage 2: Second stage for building permit clearance
After obtaining the sanction for planning (Stage 1)
from the Authority, a complete set of structural plans,
sections, details and design calculations duly signed
by engineer/structural engineer {see Annex A) along
with the complete set of details duly approved in
Stage 1 shall be submitted. The building plans/details
shall be deemed sanctioned for the commencement of
construction only after obtaining the permit for Stage 2
from the Authority.
12.2.6 Services Plans
The services plans shall include all details of building
and plumbing services, and also plans, elevations and
sections of private water supply, sewage disposal system
and rainwater harvesting system, if any {see Part 8
'Building Services' and Part 9 'Plumbing Services').
12.2.7 Specifications
Specifications, both general and detailed, giving type
and grade of materials to be used, duly signed by the
registered architect, engineer, structural engineer or
supervisor shall accompany the notice {see Annex B).
12.2.8 Structural Sufficiency Certificate
The plans shall be accompanied by structural
sufficiency certificate in the prescribed form {see
Annex C) signed by the engineer/structural engineer
{see Annex A) and the owner jointly to the effect that
the building is safe against various loads, forces and
effects including due to natural disasters, such as,
earthquake, landslides, cyclones, floods, etc as per
Part 6 'Structural Design' and other relevant Codes.
The engineer/structural engineer shall also have the
details to substantiate his design.
12.2.9 Supervision
The notice shall be further accompanied by a certificate
in the prescribed form {see Annex D) by the registered
architect/engineer/structural engineer/supervisor/town
planner {see Annex A) undertaking the supervision
{see 9.3).
12.3 Preparation and Signing of Plans
The registered architect/engineer/supervisor/town
planner/landscape architect/urban designer/utility
service engineer shall prepare and duly sign the plans
as per their competence {see Annex A) and shall
indicate his/her name, address, qualification and
registration number as allotted by the Authority or the
body governing such profession. The structural plans
and details shall also be prepared and duly signed by
the competent professionals like registered engineer/
structural engineer {see Annex A). The plans shall also
be duly signed by the own^r indicating his address.
The type and volume of buildings/development work
to be undertaken by the registered professionals may
generally be as in Annex A.
12.4 Notice for Alteration only
When the notice is only for an alteration of the building
{see 3.5), only such plans and statements, as may be
necessary, shall accompany the notice.
12.4.1 No notice and building permit is necessary for
the following alterations, and the like which do not
otherwise violate any provisions regarding general
PART 2 ADMINISTRATION
13
building requirements, structural stability and fire and
health safety requirements of the Code:
a) Opening and closing of a window or door or
ventilator;
b) Providing intercommunication doors;
c) Providing partitions;
d) Providing false ceiling;
e) Gardening;
f) White washing;
g) Painting;
h) Re-tiling and re-roofing;
j) Plastering and patch work;
k) Re-flooring; and
m) Construction of sunshades on one's own land.
12.5 Fees
No notice as referred to in 12.1 shall be deemed valid
unless and until the person giving notice has paid the
fees to the Authority and an attested copy of the receipt
of such payment is attached with the notice.
NOTE — The fees may be charged as a consolidated fee. In
the event of a building/development permit is not issued, the
fees so paid shall not be returned to the owner, but he shall be
allowed to re-submit it without any fees after complying with
all the objections raised by the Authority within a period of
one year from the date of rejection after which fresh fees shall
have to be paid.
12.6 Duration of Sanction
The sanction once accorded shall remain valid up to
three years. The permit shall be got revalidated before
the expiration of this period. Revalidation shall be
subject to the rules then in force.
12.7 Deviations During Construction
If during the construction of a building any departure
(excepting for items as given in 12.4.1) from the
sanctioned plan is intended to be made {see 7.5),
sanction of the Authority shall be obtained before the
change is made. The revised plan showing the
deviations shall be submitted and the procedure laid
down for the original plan heretofore shall apply to all
such amended plans except that the time limit specified
in 12.10.2 shall be three weeks in such cases.
12.8 Revocation of Permit
The Authority may revoke any permit issued under
the provisions of the Code, wherever there has been
any false statement, misrepresentation of any material
fact in the application on which the permit was
based or violation of building permit or in case of
noncompliance thereof, and shall state the reasons for
revoking the permit.
12.9 Qualifications of Architects/Engineers/
Structural Engineers/Landscape Architect/Urban
Designer/Supervisors/Town Planners/Services
Personnel
Architects, engineers, structural engineers, landscape
architect, urban designer, supervisors and town
planners wherever referred in the Code, shall be
registered by the Authority or the body governing such
profession constituted under a statute, as competent to
do the work for which they are employed. A guide for
the equivalent technical qualifications and professional
experience required for such registration with the
Authority is given in Annex A. In case of building and
plumbing services, qualifications for engineers for
utility services shall be as given in A-2.8.
12.9.1 In case the registered professional associated
with the preparation and signing of plans or for
supervision, is being changed during any stage of
building/land development process, the professional
shall intimate the Authority in writing about the further
non-association with the project.
12.10 Grant of Permit or Refusal
The Authority may either sanction or refuse the plans
and specifications or may sanction them with such
modifications or directions as it may deem necessary
and thereupon shall communicate its decision to the
person giving the notice {see Annex E).
12.10.1 The building plans for buildings identified
in 12.2.5.1 shall also be subject to the scrutiny of the
Fire Authority and the sanction through building permit
shall be given by the Authority after the clearance from
the Fire Authority {see also 11.1.3).
12.10.2 If within 30 days of the receipt of the notice
under 12.1 of the Code, the Authority fails to intimate
in writing to the person, who has given the notice, of
its refusal or sanction, the notice with its plans and
statements shall be deemed to have been sanctioned;
provided the fact is immediately brought to the notice
of the Authority in writing by the person who has given
notice and having not received any intimation from
the Authority within fifteen days of giving such written
notice. Subject to the conditions mentioned in this
clause, nothing shall be construed to authorize any
person to do anything in contravention of or against
the terms of lease or titles of the land or against any
other regulations, byelaws or ordinance operating on
the site of the work.
12.10.3 In the case of refusal, the Authority shall quote
the reason and relevant sections of the Code which the
plans contravene. The Authority shall as far as possible
advise all the objections to the plans and specifications
in the first instance itself and ensure that no new
14
NATIONAL BUILDING CODE OF INDIA
objections are raised when they are resubmitted after
compliance of earlier objections.
12.10.4 Once the plan has been scrutinized and
objections have been pointed out, the owner giving
notice shall modify the plan to comply with the
objections raised and re-submit it. The Authority shall
scrutinize the re-submitted plan and if there be further
objections, the plan shall be rejected.
13 RESPONSIBILITIES AND DUTIES OF THE
OWNER
13.1 Neither the granting of the permit nor the approval
of the drawings and specifications, nor inspections
made by the Authority during erection of the building
shall in any way relieve the owner of such building
from full responsibility for carrying out the work in
accordance with the requirements of the Code (see 9).
13.2 Every owner shall:
a) permit the Authority to enter the building or
premises for which the permit has been
granted at any reasonable time for the purpose
of enforcing the Code;
b) submit a document of ownership of the site;
c) obtain, where applicable, from the Authority,
permits relating to building, zoning, grades,
sewers, water mains, plumbing, signs,
blasting, street occupancy, electricity,
highways, and all other permits required in
connection with the proposed work;
d) give notice to the Authority of the intention
to start work on the building site (see
Annex F);
e) give written notice to the Authority intimating
completion of work up to plinth level;
f) submit the certificate for execution of work
as per structural safety requirements (see
Annex G); and give written notice to the
Authority regarding completion of work
described in the permit (see Annex H);
g) give written notice to the Authority in case of
termination of services of a professional
engaged by him; and
h) obtain an occupancy permit (see Annex J)
from the Authority prior to any:
1 ) occupancy of the building or part thereof
after construction or alteration of that
building or part, or
2) change in the class of occupancy of any
building or part thereof.
13.2.1 Temporary Occupancy
Upon the request of the holder of the permit, the
Authority may issue a temporary certificate of
occupancy for a building or part thereof, before the
entire work covered by permit shall have been
completed, provided such portion or portions may be
occupied safely prior to full completion of building
without endangering life or public welfare.
13.3 Documents at Site
13.3.1 Where tests of any materials are made to ensure
conformity with the requirements of the Code, records
of the test data shall be kept available for inspection
during the construction of the building and for such a
period thereafter as required by the Authority.
13.3.2 The person to whom a permit is issued shall
during construction keep pasted in a conspicuous place
on the property in respect of which the permit was
issued:
a) a copy of the building permit; and
b) a copy of the approved drawings and
specifications referred in 12.
14 INSPECTION, OCCUPANCY PERMIT AND
POST-OCCUPANCY INSPECTION
14.1 Generally all construction or work for which a
permit is required shall be subject to inspection by the
Authority and certain types of construction involving
unusual hazards or requiring constant inspection shall
have continuous inspection by special inspectors
appointed by the Authority.
14.2 Inspection, where required, shall be made within
7 days following the receipt of notification, after
which period the owner will be free to continue the
construction according to the sanctioned plan. At the
first inspection, the Authority shall determine to the
best of its ability that the building has been located
in accordance with the approved site plans. The final
inspection of the completion of the work shall be
made within 21 days following the receipt of
notification [see 13.2(f)] for the grant of occupancy
certificate.
14.2.1 The owner/concerned registered architect/
engineer/structural engineer/town planner will serve
a notice/completion certificate to the Authority that
the building has been completed in all respects as per
the approved plans. The deviations shall also be
brought to the notice of the Authority (with relevant
documents). The team of building officials or its duly
authorized representative shall then visit the site and
occupancy certificate shall be given in one instance.
14.2.2 The occupancy certificate should clearly state
the use/type of occupancy of the building. However,
the applicant can apply for change of use/occupancy
permitted within the purview of the Master Plan/Zonal
Plan/Building Byelaws, where so required.
PART 2 ADMINISTRATION
15
14.3 When inspection of any construction operation
reveals than any lack of safety precautions exist, the
Authority shall have right to direct the owner to stop
the work immediately until the necessary remedial
measures to remove the violation of safety precautions
are taken.
14.4 Periodic Occupancy Renewal Certificate
14.4.1 For buildings covered in 12.2.5.1 after
completion of the building and obtaining the occupancy
certificate, periodic inspections of buildings shall be
made by the Fire Authority to ensure the fire safety of
the building and compliance with the provisions of fire
and life safety requirements (see Part 4 Tire and Life
Safey'). Periodic occupancy renewal certificate shall
be made available by the Authority/Fire Authority which
shall also include safekeep of fire fighting installations
and equipments for such buildings.
14.4.2 All occupied building and buildings covered
under 12.2.5.1 shall also be subjected to periodic
physical inspection by a team of multi-disciplinary
professionals of local Authority. The work by team of
professionals may be outsourced by the Authority to
competent professionals as may be deemed necessary.
The team shall ensure the compliance of byelaws,
natural lighting, ventilation, etc, besides structural and
electrical safety. After checking, the team shall be
required to give the certificate for above aspects. If
any shortcoming/deficiencies or violations are noticed
during inspection, the Authority shall ensure the
compliance of these within a specified time frame of
six months. If not complied with, the building shall be
declared unsafe. The period of inspection shall usually
be 3 to 5 years but in any case not more than 5 years.
15 UNSAFE BUILDING
15.1 All unsafe buildings shall be considered to
constitute danger to public safety and shall be restored
by repairs or demolished or dealt with as otherwise
directed by the Authority (see 15.2 to 15.5).
15.2 Examination of Unsafe Building
The Authority shall examine or cause to be examined
every building reported to be unsafe or damaged, and
shall make a written record of such examination.
15.3 Notice to Owner, Occupier
Whenever the Authority finds any building or portion
thereof to be unsafe, it shall, in accordance with
established procedure for legal notice, give to the owner
and occupier of such building written notices stating
the defects thereof. This notice shall require the owner
or the occupier within a stated time either to complete
specified repairs or improvements or to demolish and
remove the building or portion thereof.
15.3.1 The Authority may direct in writing that the
building which in his opinion is dangerous, or has
no provision for exit if caught fire, shall be vacated
immediately or within the period specified for the
purpose; provided that the Authority concerned shall
keep a record of the reasons for such action with
him.
If any person does not comply with the orders of
vacating a building, the Authority may direct the police
to remove the person from the building and the police
shall comply with the orders.
15.4 Disregard of Notice
In case the owner or occupier fails, neglects, or refuses
to comply with the notice to repair or to demolish the
said building or portion thereof, the Authority shall
cause the danger to be removed whether by demolition
or repair of the building or portion thereof or otherwise.
15.5 Cases of Emergency
In case of emergency, which, in the opinion of the
Authority involves imminent danger to human life or
health, the decision of the Authority shall be final. The
Authority shall forthwith or with such notice as may
be possible promptly cause such building or portion
thereof to be rendered safe by retrofitting/strengthening
to the same degree of safety or removed. For this
purpose, the Authority may at once enter such structure
or land on which it stands, or abutting land or structure,
with such assistance and at such cost as may be deemed
necessary. The Authority may also get the adjacent
structures vacated and protect the public by an
appropriate fence or such other means as may be
necessary.
15.6 Costs
Costs incurred under 15.4 and 15.5 shall be charged to
the owner of the premises involved. Such costs shall
be charged on the premises in respect of which or for
the benefit of which the same have been incurred and
shall be recoverable as provided under the laws (see
Note).
NOTE — The costs may be in the form of arrears of taxes.
16 DEMOLITION OF BUILDING
Before a building is demolished, the owner shall notify
all utilities having service connections within the
building, such as water, electric, gas, sewer and other
connections. A permit to demolish a building shall not
be issued until a release is obtained from the utilities
stating that their respective service connections and
appurtenant equipment, such as, meters and regulators
have been removed or sealed and plugged in a safe
manner.
16
NATIONAL BUILDING CODE OF INDIA
17 VALIDITY
17.1 Partial Invalidity
In the event any part or provision of the Code is held
to be illegal or void, this shall not have the effect of
making void or illegal any of the other parts or
provisions thereof, which may or shall be determined
to be legal, and it shall be presumed that the Code
would have been passed without such illegal or invalid
parts or provisions.
17.2 Segregation of Invalid Provisions
Any invalid part of the Code shall be segregated
from the remainder of the Code by the court holding
such part invalid, and the remainder shall remain
effective.
17.3 Decisions Involving Existing Buildings
The invalidity of any provision in any clause of the
Code as applied to existing buildings and structures
shall not be held to effect the validity of such section
in its application to buildings hereafter erected.
18 ARCHITECTURAL CONTROL
18.1 Compliance with the provisions of the Code is
adequate for normal buildings. But for major public
building complexes or buildings coming up in an
important area near historic/monumental buildings and
areas of heritage, the aesthetics of the whole scheme
may also have to be examined, vis-a-vis existing
structures. In addition, any development which may
mar the general characteristics and environment of
historical, architectural or other monuments should also
be subject to the provisions of this clause. This clause
is intended to cover very few structures to come up in
the vicinity of other declared/historically important
structures, and the scrutiny shall be limited to the
external architectural features only so as to ensure an
aesthetic continuance of the existing structures with
the new. The scrutiny shall not deal with the routine
building plan scrutiny from other requirements of
Code from the point of view of structural safety and
functional requirements.
18.2 An Urban Arts Commission shall be established
at the city/state level on issues related to urban
aesthetics, through a statute. This statutory authority/
commission established by an Act of State Legislative
Assembly, shall accord approval to all major buildings/
important development projects having bearing on the
urban aesthetics, depending upon the importance of
the area with respect to natural or built heritage or
projects on plot areas above 1 hectare and located
in specifically identified areas. The Urban Arts
Commission shall act as guardian of urban architecture;
mainly with regard to building form and envelope, the
relationship between the building, and the ambient
environment vis-a-vis other dependants should be seen
in depth.
18.3 The Commission may work in the following
manner:
a) The Commission may select only the
important buildings as in 18.1 and examine
the same. The person responsible for the
schemes, say an architect or an engineer, may
examine either alone or with the owner. A
study of the plans, elevations, models, etc,
should be made. The architect/engineer
should explain in general terms the purposes
which the building is to serve and the main
conditions which have influenced him in
preparing the design.
b) The Commission after full discussion, may
communicate their decision in writing to the
parties concerned. The Commission may
recommend a change in the whole scheme or
suggest modifications in the existing scheme,
if so required.
18.4 The Urban Arts Commission should also be
charged with advising the city government, on schemes
which will beautify the city and add to its cultural
vitality.
PART 2 ADMINISTRATION
17
ANNEX A
(Foreword and Clauses 2.17, 6.5, 6.6, 9.1.3, 12.2.8, 12.3 and 12.9)
GUIDE FOR THE QUALIFICATIONS AND COMPETENCE OF PROFESSIONALS
A-l ESSENTIAL REQUIREMENTS
A-l.l Every building/development work for which
permission is sought under the Code shall be planned,
designed and supervised by registered professionals.
The registered professionals for carrying out the
various activities shall be: (a) architect, (b) engineer,
(c) structural engineer, (d) supervisor, (e) town planner,
(f) landscape architect, (g) urban designer, and
(h) utility service engineer. Requirements of
registration for various professionals by the Authority
or by the body governing such profession and
constituted under a statute, as applicable to practice
within the local body's jurisdiction, are given in A-2.1
to A-2.5. The competence of such registered personnel
to carry out various activities is also indicated
inA-2.1.1 to A-2.5.1.
A-2 REQUIREMENTS FOR REGISTRATION
AND COMPETENCE OF PROFESSIONALS
A-2.1 Architect
The minimum qualifications for an architect shall be
the qualifications as provided for in the Architects Act,
1972 for registration with the Council of Architecture.
A-2. 1.1 Competence
The registered architect shall be competent to carryout
the work related to the building/development permit
as given below:
a) All plans and information connected with
building permit except engineering services
of multistoreyed/special buildings given
in 12.2.5.1.
b) Issuing certificate of supervision and
completion of all buildings pertaining to
architectural aspects.
c) Preparation of sub-division/layout plans and
related information connected with
development permit of area up to 1 hectare
for metro-cities and 2 hectare for other places.
d) Issuing certificate of supervision for
development of land of area up to 1 hectare
for metro-cities and 2 hectare for other places.
A-2.2 Engineer
The minimum qualifications for an engineer shall be
graduate in civil engineering/architectural engineering
of recognized Indian or foreign university, or the
Member of Civil Engineering Division/ Architectural
Engineering Division of the Institution of Engineers
(India) or the statutory body governing such profession,
as and when established.
A-2.2.1 Competence
The registered engineer shall be competent to carryout
the work related to the building/development permit
as given below:
a) All plans and information connected with
building permit;
b) Structural details and calculations of buildings
on plot up to 500 m 2 and up to 5 storeys or
16 m in height;
c) Issuing certificate of supervision and
completion for all buildings;
d) Preparation of all service plans and related
information connected with development
permit; and
e) Issuing certificate of supervision for
development of land for all area.
A-2.3 Structural Engineer
The minimum qualifications for a structural engineer
shall be graduate in civil engineering of recognized
Indian or foreign university, or Corporate Member of
Civil Engineering Division of Institution of Engineers
(India), and with minimum 3 years experience in
structural engineering practice with designing and field
work.
NOTE — The 3 years experience shall be relaxed to 2 years in
the case of post-graduate degree of recognized Indian or foreign
university in the branch of structural engineering. In case of
doctorate in structural engineering, the experience required
would be one year.
A-2.3.1 Competence
The registered structural engineer shall be competent
to prepare the structural design, calculations and details
for all buildings and supervision.
A-2.3.1.1 In case of buildings having special structural
features, as decided by the Authority, which are within
the horizontal areas and vertical limits specified
in A-2.2.1 (b) and A-2.4.1(a) shall be designed only
by structural engineers.
A-2.4 Supervisor
The minimum qualifications for a supervisor shall
be diploma in civil engineering or architectural
assistantship, or the qualification in architecture or
18
NATIONAL BUILDING CODE OF INDIA
engineering equivalent to the minimum qualification
prescribed for recruitment to non-gazetted service by
the Government of India plus 5 years experience in
building design, construction and supervision.
A-2.4.1 Competence
The registered supervisor shall be competent to carryout
the work related to the building permit as given below:
a) All plans and related information connected
with building permit for residential buildings
on plot up to 100 m 2 and up to two storeys or
7.5 m in height; and
b) Issuing certificate of supervision for buildings
as per (a).
A-2.5 Town Planner
The minimum qualification for a town planner shall
be the Associate Membership of the Institute of Town
Planners or graduate or post-graduate degree in town
and country planning.
A-2.5.1 Competence
The registered town planner shall be competent to
carryout the work related to the development permit
as given below:
a) Preparation of plans for land sub-division/
layout and related information connected with
development permit for all areas.
b) Issuing of certificate of supervision for
development of land of all areas.
NOTE — However, for land layouts for development
permit above 5 hectare in area, landscape architect
shall also be associated, and for land development
infrastructural services for roads, water supplies,
sewerage/drainage, electrification, etc, the registered
engineers for utility services shall be associated.
A-2.6 Landscape Architect
The minimum qualification for a landscape architect
shall be the bachelor or master' s degree in landscape
architecture or equivalent from recognized Indian or
foreign university.
A-2,6.1 Competence
The registered landscape architect shall be competent
to carryout the work related to landscape design for
building/development permit for land areas 5 hectares
and above. In case of metro-cities, this limit of land
area shall be 2 hectares and above.
NOTE — For smaller areas below the limits indicated above,
association of landscape architect may also be considered from
the point of view of desired landscape development.
A-2.7 Urban Designer
The minimum qualification for an urban designer shall
be the master's degree in urban design or equivalent
from recognized Indian or foreign university.
A-2.7.1 Competence
The registered urban designer shall be competent to
carryout the work related to the building permit for
urban design for land areas more than 5 hectares and
campus area more than 2 hectares. He/She shall also
be competent to carryout the work of urban renewal
for all areas.
NOTE — For smaller areas below the limits indicated above,
association of urban designer may be considered from the point
of view of desired urban design.
A-2.8 Engineers for Utility Services
For buildings identified in 12.2.5.1, the work of
building and plumbing services shall be executed under
the planning, design and supervision of competent
personnel. The qualification for registered mechanical
engineer (including HVAC), electrical engineer and
plumbing engineers for carrying out the work of Air-
conditioning, Heating and Mechanical Ventilation,
Electrical Installations, Lifts and Escalators and Water
Supply, Drainage, Sanitation and Gas Supply
installations respectively shall be as given in Part 8
'Building Services' and Part 9 'Plumbing Services' or
as decided by the Authority taking into account
practices of the National professional bodies dealing
with the specialist engineering services.
A-3 BUILDER/CONSTRUCTOR ENTITY
The minimum qualification and competence for the
builder/constructor entity for various categories of
building and infrastructural development shall be as
decided by the Authority to ensure compliance of
quality, safety and construction practices as required
under the Code.
PART 2 ADMINISTRATION
19
ANNEX B
(Clause 12.1)
FORM FOR FIRST APPLICATION TO DEVELOP, ERECT, RE-ERECT OR TO MAKE
ALTERATION IN ANY PLACE IN A BUILDING
To
Sir,
I hereby give notice that I intend to develop, erect, re-erect or to make alteration in the building No
or to on/in Plot No in Colony/
Street MOHALLA/BAZAR/Rond City and
in accordance with the building code of Part II, Clauses and
I f orw ard herewith the following plans and specifications in triplicate duly signed by me and
the Architect/Engineer/Structural Engineer/Supervisor/Town Planner/Landscape Architect/Urban Designer 1 *,
Registration No who will supervise its erection.
(Name in block letters)
1 . Key plan
2. Site plans
3. Sub-division/layout plan
4. Building plans
5. Services plans
6. Specifications, general and detailed 2)
7 . Title of ownership of land/building
8. Certificates for structural sufficiency and supervision
I request that the development/construction may be approved and permission accorded to me to execute the
work.
Signature of Owner
Name of the Owner
(in block letters)
Address of Owner
Date:
Strike out whichever is not applicable.
2) A format may be prepared by the Authority for direct use.
20
NATIONAL BUILDING CODE OF INDIA
ANNEX C
(Clause 12.2.8)
FORM FOR CERTIFICATE FOR STRUCTURAL DESIGN SUFFICIENCY
With respect to the building work of erection, re-erection or for making alteration in the building
No or to on/in Plot No Colony/
Street MOHALLA/BAZARfRozd City ,
we certify that the structural plans and details of the building submitted for approval satisfy the structural safety
requirements for all situations including natural disasters, as applicable, as stipulated under Part 6 Structural
Design of the National Building Code of India and other relevant Codes; and the information given therein is
factually correct to the best of our knowledge and understanding.
Signature of owner
with date
Name:
Signature of the
Registered Engineer/
Structural Engineer with
date and registration No.
Address:
ANNEX D
(Clause 12.2.9)
FORM FOR SUPERVISION
I hereby certify that the development, erection, re-erection or material alteration in/of building No
or the on/in Plot No in Colony/
Street MOHALLAIBAZARfRozd City
shall be carried out under my supervision and I certify that all the materials (type and grade) and the workmanship
of the work shall be generally in accordance with the general and detailed specifications submitted along with,
and that the work shall be carried out according to the sanctioned plans.
Signature of Architect/Engineer/Structural Engineer/Supervisor/Town Planner/Landscape Architect/Urban
Designer^
Name of Architect/Engineer/Structural Engineer/Supervisor/Town Planner/Landscape Architect/Urban
Designer
(in block letters)
Registration No. of Architect/Engineer/Structural Engineer/Supervisor/Town Planner/Landscape Architect/Urban
Designer^
Address of Architect/Engineer/Structural Engineer/Supervisor/Town Planner/Landscape Architect/Urban
Designer ])
Date:
Strike out whichever is not applicable.
PART 2 ADMINISTRATION 21
ANNEX E
(Clause 12.10)
FORM FOR SANCTION OR REFUSAL OF DEVELOPMENT/BUILDING PERMIT
To
Sir,
With reference to your application dated for grant of permit
for the development, erection, re-erection or material alteration in the building No
or to on/in Plot No in Colony/
Street MOHALLA/BAZAR/Rozd City
I have to inform you that the sanction has been granted/refused by the Authority on the following grounds:
1.
2.
3.
4.
5.
6.
Office Stamp Signature of the Authority
Office (Communication) No Name, Designation and Address
of the Authority
Date:
ANNEX F
[Clause 13.2 (d)]
FORM FOR NOTICE FOR COMMENCEMENT
I hereby certify that the development, erection, re-erection or material alteration in/of building No
or the on/in Plot No in Colony/Street MOHALLA/
BAZAR/Road City will be commenced on as per your permission,
vide No dated under the supervision of Registered
Architect/Engineer/Structural Engineer/Supervisor/Town Planner/Landscape Architect/Urban Designer 1 *,
Registration No and in accordance witji the plans sanctioned, vide
No dated
Signature of Owner
Name of Owner
(in block letters)
Address of Owner.
Date:
1} Strike out whichever is not applicable.
22 NATIONAL BUILDING CODE OF INDIA
ANNEX G
[Clause 13.2(f)]
FORM FOR CERTIFICATE FOR EXECUTION OF WORK AS PER
STRUCTURAL SAFETY REQUIREMENTS
With respect to the building work of erection, re-erection or for making alteration in the building No
or to on/in Plot No Colony/Street MOHALLA/
BAZARfRoad City , we certify:
a) that the building has been constructed according to the sanctioned plan and structural design (one set of
drawings as executed enclosed), which incorporates the provisions of structural safety as specified in
Part 6 'Structural Design' of the National Building Code of India and other relevant Codes; and
b) that the construction has been done under our supervision and guidance and adheres to the drawings and
specifications submitted and records of supervision have been maintained.
Any subsequent changes from the completion drawings shall be the responsibility of the owner.
Signature of owner Signature of the
with date Registered Engineer/
Structural Engineer with
date and registration No.
Name:
Address:
ANNEX H
[Clause 13.2(f)]
FORM FOR COMPLETION CERTIFICATE
I hereby certify that the development, erection, re-erection or material alteration in/of building No
or the on/in Plot No in Colony/Street MOHALLA/ BAZAR/
Road City has been supervised by me and has been completed on
according to the plans sanctioned, vide No dated The work
has been completed to my best satisfaction, the workmanship and all the materials (type and grade) have been
used strictly in accordance with general and detailed specifications. No provisions of the Code, no requisitions
made, conditions prescribed or orders issued thereunder have been transgressed in the course of the work. The
land is fit for construction for which it has been developed or re-developed or the building is fit for use for which
it has been erected, re-erected or altered, constructed and enlarged.
I hereby also enclose the plan of the building completed in all aspects.
Signature of Architect/Engineer/Structural Engineer/Supervisor/Town Planner/Landscape Architect/Urban
Designer
Name of Architect/Engineer/Structural Engineer/Supervisor/Town Planner/Laridscape Architect/Urban
Designer
(in block letters)
Registration No. of Architect/Engineer/Structural Engineer/Supervisor/Town Planner/Landscape Architect/Urban
Designer
Address of Architect/Engineer/Structural Engineer/Supervisor/Town Planner/Landscape Architect/Urban
Designer
Date: Signature of the Owner
Strike out whichever is not applicable.
PART 2 ADMINISTRATION 23
ANNEX J
[Clause 13.2(h)]
FORM FOR OCCUPANCY PERMIT
The work of erection, re-erection or alteration in/of building No or the on/
in Plot No in Colony/Street.... MOHAIIAIBAZARIRozd
City completed under the supervision of. Architect/Engineer/Structural
Engineer/Supervisor, Registration No has been inspected by me. The building can be permitted/
not permitted for occupation for occupancy subjected to the following:
1.
2.
3.
One set of completion plans duly certified is returned herewith.
Signature of the Authority
Office Stamp
Date:
24 NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 3 DEVELOPMENT CONTROL RULES AND
GENERAL BLTLDING REQUIREMENTS
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD ... 3
1 SCOPE ... 7
2 TERMINOLOGY ... 7
3 LAND USE CLASSIFICATION AND USES PERMITTED ... 12
4 MEANS OF ACCESS ... 13
5 COMMUNITY OPEN SPACES AND AMENITIES ... 15
6 REQUIREMENTS OF PLOTS ... 21
7 CLASSIFICATION OF BUILDINGS ... 22
8 OPEN SPACES (WITHIN A PLOT) ... 23
9 AREA AND HEIGHT LIMITATIONS ... 26
10 OFF-STREET PARKING SPACES ... 28
1 1 GREENBELTS, LANDSCAPING AND WATER CONSERVATION ... 29
1 2 REQUIREMENTS OF PARTS OR BUILDINGS ... 29
13 FIRE AND LIFE SAFETY ... 34
1 4 DESIGN AND CONSTRUCTION ... 34
1 5 LIGHTING AND VENTILATION ... 34
1 6 ELECTRICAL AND ALLIED INSTALLATIONS (INCLUDING LIGHTNING ... 35
PROTECTION OF BUILDINGS)
17 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION ... 35
1 8 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL ... 35
19 HEAT INSULATION ... 35
20 INSTALLATION OF LIFTS AND ESCALATORS ... 35
21 PLUMBING SERVICES AND SOLID WASTE MANAGEMENT ... 35
ANNEX A CIVIL AVIATION REQUIREMENTS FOR CONSTRUCTION IN ... 36
THE VICINITY OF AN AERODROME.
ANNEX B OFF-STREET PARKING SPACES ... 41
ANNEX C SPECIAL REQUIREMENTS FOR LOW INCOME HOUSING IN ... 42
URBAN AREAS
ANNEX D SPECIAL REQUIREMENTS FOR PLANNING OF PUBLIC ... 45
BUILDINGS MEANT FOR USE OF PHYSICALLY CHALLENGED
ANNEX E SPECIAL REQUIREMENTS OF CLUSTER PLANNING FOR ... 56
HOUSING
ANNEX F SPECIAL REQUIREMENTS FOR LOW INCOME HABITAT ... 57
PLANNING IN RURAL AREAS
ANNEX G SPECIAL REQUIREMENTS FOR DEVELOPMENT PLANNING ... 60
IN HILLY AREAS
LIST OF STANDARDS ... 63
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
This Part covers development control rules, including such aspects as sub-division and layout rules, land use
classifications, open spaces, area and height limitations, means of access, and parking spaces; this part also
covers the general building requirements, such as the requirements of parts of buildings, provision of lifts, etc.
It is expected that for proper coordination and enforcement of the development control rules and general building
requirements, the departments concerned, namely, the town planning department and the building department,
will coordinate the total development and building activity at both organizational and technical levels.
Particular attention is invited to Table 3 on floor area ratio (FAR) limitations. It is emphasized that the floor area
of a single storey building is limited in absolute terms by the type of construction and occupancy class. Also, the
absolute floor areas for different types of construction and different occupancies have a definite ratio among
them. The ratios as recommended in the American Iron and Steel Institute publication 1961 Tire Protection
Through Modern Building Codes' have been generally adopted in this Part and Table 3 has been developed on
this basis. Table 3 is repeated in Part 4 Tire and Life Safety' also for convenience of reading.
Limitation of areas and heights of buildings is achieved in this country by specifying it in terms of floor area ratio
(FAR) or floor space index (FSI). The significance of the contribution of different types of construction giving
different fire resistances has not been taken cognizance of in specifying FAR for different occupancies, in the
present development control rules and municipal byelaws of the country. Table 3, therefore, gives the comparative
ratios of FAR between types of buildings and occupancy classes and these have been specified mainly from the
fire protection aspect of buildings. To arrive at the actual FAR for different buildings coming up in different
areas, the Authority should further modify them, by taking into consideration other aspects like density of any
area, parking facilities required, the traffic load (road width) and the services available. The heights of buildings
shall also be regulated, keeping in view the local fire fighting facilities.
In some state byelaws, the FAR (or FSI) has been expressed in the form of percentage. However, the Committee
responsible for preparation of this Code is of the opinion that, it being a ratio should be expressed only in the
form of a ratio, as done in this Part.
It is particularly to be borne in mind by the Authority that the ratios are definitive and it can assess the particular
FAR for a type of construction and for an occupancy and establish a new table, but retaining the comparative
ratios as given in Table 3.
Keeping in view the enormous problems faced by the country with regard to the ever increasing squatter settlements/
pavement dwellers in urban areas (cities of all sizes), it is imperative that all the urban local bodies sooner or later
evolve schemes for their rehabilitation. The resources are meagre and the problems are enormous. There has
been a tendency on the part of a number of development agencies/local bodies to link space norms with
affordability. Affordability is an important criterion but at the same time a public agency cannot ignore the basic
minimum needs of the family to be housed (including the mental, physical and social health of the marginalized
groups, which is linked with shelter). The local bodies shall have to evolve appropriate policies for their integration
with the broad urban society and generate/allocate resources and more importantly adopt a planning process,
which are people friendly. The Government of India has also formulated the National Slum Policy to this effect
Therefore, keeping in view the needs of low income housing, to cater to Economically Weaker Sections of
Society (EWS) and Low Income Group (LIG), the requirements on planning, design of layout/shelter have
been rationalized and the same are provided in this Part. This will contribute significantly in the massive
housing programmes undertaken for the low income sector. This information is based on the provisions
of IS 8888 (Part 1) : 1993 'Guide for requirements of low income housing: Part 1 Urban areas (first revision)' .
Further, city development process would need a dynamic approach to take care of urban renewal and also
development needs in dense core areas of the cities. Innovative approaches in planning and design with participating
models of public private-people's partnership become necessary to solve the emerging development needs. With
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS 3
this in view, many city development agencies have evolved innovative planning and development tools like
transferable development rights (TDR) where the developer would receive a portion of the development rights in
a new location, keeping in view the constraints in the existing land area and the development potential. Such
development rights can be transferred into outskirts or new developed areas where land availability is assured.
This would encourage the professionals and developers to participate in urban renewal and at the same time
ensure that the developments in both the inner core areas and new areas take place in an orderly and efficient
manner. The TDR concept should be increasingly encouraged by the authority dealing with urban renewal, re-
development projects including housing and re-development projects for slum including dwellers.
Urbanization in India is taking place at a rapid pace. With 5 million population in cities at the time of independence,
it has already crossed 28 million (2001 census). It is likely to be 50 million by 2021. The number of cities and
towns have been expanding and there are 5 161 cities and towns of various sizes. In the Indian practice cities
over 50 lakhs population have been identified as mega-cities (6 in number) and cities over 10 lakhs (29 in
number) population as metro-cities. These 35 cities above 10 lakhs population is likely to be above 70 by 2021.
The other cities are either small or medium towns or cities with different population limits. Urbanization in each
of above cities and towns (mega-cities, metro-cities, small and medium towns and cities) will be different in
nature and the development challenges are also different keeping in view the extent of urbanization,
industrialization, commercialization and the nature of transportation needs. Therefore, the Code provisions should
be appropriately utilized depending upon the need of hierarchy of cities for which the administrative and technical
requirements have been covered in the Code for various facets of the activity.
The first version of this Part was prepared in 1970. As a result of incorporation of this Part in the revised
development control rules and building byelaws of some municipal corporations and municipalities, some useful
suggestions had emerged. First revision of this part was brought out in 1983, where these suggestions were
incorporated to the extent possible. The major modifications incorporated in the first revision included:
a) Addition of development control rules giving guidance on means of access, community spaces and
other aspects required for planning layouts.
b) Addition of provisions regarding plot sizes and frontage for different types of buildings, such as detached,
semi-detached, row type and special housing schemes.
c) Requirements of open spaces for other occupancies, such as educational, institutional, assembly, industrial
buildings, etc, were included.
d) Provisions relating to interior open space were elaborated, including requirements for ventilation shaft.
e) Requirements of open spaces for group housing development were covered.
f) Requirements of off-street parking spaces were covered.
g) Requirements for greenbelts and landscaping including norms for plantations of shrubs and trees were
covered.
h) Requirements of certain parts of buildings, such as loft, store room, garage, basement, chimney, parapet,
cabin, boundary wall, wells, septic tanks, office-cum-letter box room, meter room were included.
j) Special requirements of low income housing were covered.
The term Development Control Rules used in this Part encompasses the related aspects comprehensively with a
view to promoting orderly development of an area.
This second revision is being brought out to incorporate the modifications found necessary in light of the experience
gained with the use of this Part. Significant modifications incorporated in this revision include:
a) Terminology given in this Part has been made exhaustive by incorporating definitions of additional
terms used, such as, access, chimney, to erect, etc, and number of terms pertaining to cluster planning
for housing.
b) Detailed planning norms/open spaces for various amenities such as educational facilities, health care
facilities, socio-cultural facilities, distribution services, police, civil defence and home guards, and fire
services have been included.
c) Off-street parking requirements have now been also included for cities with population (i) between
1 000 000 and 5 000 000, and (ii) above 5 000 000 (see Annex B).
d) Special requirements for low income housing given in the earlier version have been modified and
updated (see Annex C) based on IS 8888 (Part 1) : 1993 'Guide for requirements of low income housing:
4 NATIONAL BUILDING CODE OF INDIA
Part 1 Urban area (first revision)' . In these revised provisions, single room dwelling has been discouraged,
guidelines for water seal latrine have also been incorporated, and cluster planning approach has been
recommended.
e) Requirements for cluster planning for housing have been added (see Annex E), which are based on the
guidelines given in IS 13727 : 1993 'Guide for requirements of cluster planning for housing'.
f) Special requirements for low income housing for rural habitat planning has been added (see Annex F).
g) Special requirements for development planning in hilly areas has been added (see Annex G).
h) The requirements for buildings and facilities for the physically challenged have been revised, with
listing of additional categories of physically challenged; modifications in requirements of ramps, stairs,
doors, handrails and controls; and incorporation of additional requirements regarding windows.
j) Also, the opportunity has been utilized to update the reference to Indian Standards.
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
NATIONAL BUILDING CODE OF INDIA
PART 3 DEVELOPMENT CONTROL RULES AND
GENERAL BUILDING REQUIREMENTS
1 SCOPE
This Part deals with the development control rules and
general building requirements to ensure health and
safety of the public.
2 TERMINOLOGY
2.0 For the purpose of this part, the following
definitions shall apply:
2.1 Access — A clear approach to a plot or a building.
2.2 Accessory Use — Any use of the premises
subordinate to the principal use and customarily
incidental to the principal use.
2.3 Alteration — A change from one occupancy to
another, or a structural change, such as an addition to
the area or height, or the removal of part of a building,
or any change to the structure, such as the construction
of, cutting into or removal of any wall, partition,
column, beam, joist, floor or other support, or a change
to or closing of any required means of ingress or egress
or a change to the fixtures or equipment.
2.4 Approved — Approved by the Authority having
jurisdiction.
2.5 Authority Having Jurisdiction — The Authority
which has been created by a statute and which for the
purpose of administering the Code/Part may authorize
a committee or an official to act on its behalf;
hereinafter called the 'Authority'.
2.6 Back-to-Back Cluster — Clusters when joined
back to back and/or on sides (see Fig. 1).
Fig. 1 Back-to-Back Cluster
2.7 Balcony — A horizontal projection, with a
handrail or balustrade or a parapet, to serve as passage
or sitting out place.
2.8 Basement or Cellar — The lower storey of a
building below or partly below ground level.
2.9 Building — Any structure for whatsoever purpose
and of whatsoever materials constructed and every part
thereof whether used as human habitation or not and
includes foundation, plinth, walls, floors, roofs,
chimneys, plumbing and building services, fixed
platforms, VERANDAH, balcony, cornice or projection,
part of a building or anything affixed thereto or any
wall enclosing or intended to enclose any land or space
and signs and outdoor display structures. Tents,
SHAMIANAHS, tarpaulin shelters, etc, erected for
temporary and ceremonial occasions with the permission
of the Authority shall not be considered as building.
2.10 Building, Height of — The vertical distance
measured in the case of flat roofs, from the average
level of the ground around and contiguous to the
building or as decided by the Authority to the terrace
of last livable floor of the building adjacent to the
external walls; and in the case of pitched roofs, up to
the point where the external surface of the outer wall
intersects the finished surface of the sloping roof; and
in the case of gables facing the road, the mid-point
between the eaves level and the ridge. Architectural
features serving no other function except that of
decoration shall be excluded for the purpose of
measuring heights.
2.11 Building Envelope — The horizontal spatial
limits up to which a building may be permitted to be
constructed on a plot.
2.12 Building Line — The line up to which the plinth
of a building adjoining a street or an extension of a
street or on a future street may lawfully extend. It
includes the lines prescribed, if any, in any scheme.
The building line may change from time-to-time as
decided by the Authority.
2.13 Cabin — A non-residential enclosure constructed
of non-load bearing partition.
2.14 Canopy — A projection over any entrance.
2.15 Carpet Area — The covered area of the usable
rooms at any floor level (excluding the area of the wall).
2.16 CHHAJJA — A sloping or horizontal structural
overhang usually provided over openings on external
walls to provide protection from sun and rain.
2.17 Chimney — An upright shaft containing one or
more flues provided for the conveyance to the outer
air of any product of combustion resulting from the
operation of heat producing appliance or equipment
employing solid, liquid or gaseous fuel.
2.18 Chowk or Courtyard — A space permanently
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BtlLDING REQUIREMENTS
open to the sky, enclosed fully or partially by building
and may be at ground level or any other level within
or adjacent to a building.
2.19 Chowk, Inner — A chowk enclosed on all sides.
2.20 Chowk, Outer — A chowk one of whose sides
is not enclosed.
2.21 Closed Clusters — Clusters with only one
common entry into cluster open space (see Fig. 2).
2.22 Cluster — Plots or dwelling units or housing
grouped around an open space (see Fig. 3).
Ideally housing cluster should not be very large. In
ground and one storey ed structures not more than 20
houses should be grouped in a cluster. Clusters with
more dwelling units will create problems in identity,
encroachments and of maintenance.
2.23 Cluster Court Town House — A dwelling in a
cluster plot having 100 percent or nearly 100 percent
ground coverage with vertical expansion, generally
limited to one floor only and meant for self use.
2.24 Cluster Plot — Plot in a cluster.
2.25 Cooking Alcove — A cooking space having
direct access from the main room without any inter-
communicating door.
2.26 Covered Area — Ground area covered by the
building immediately above the plinth level. The area
covered by the following in the open spaces is excluded
from covered area (see Table 3):
a) Garden, rockery, well and well structures,
plant nursery, waterpool, swimming pool (if
uncovered), platform round a tree, tank,
fountain, bench, CHABUTRA with open top
and unenclosed on sides by walls and the like;
b) Drainage culvert, conduit, catch-pit, gully pit,
chamber, gutter and the like;
c) Compound wall, gate, unstoreyed porch and
portico, canopy, slide, swing, uncovered
staircase, ramps areas covered by CHHAJJA
and the like; and
d) Watchmen's booth, pumphouse, garbage
shaft, electric cabin or sub-stations, and such
other utility structures meant for the services
of the building under consideration.
NOTE — For the purpose of this Part, covered area
equals the plot area minus the area due for open spaces.
-one common entry-
Fig. 2 Closed Cluster
GROUP OPEN
SPACE IN A, CLUSTER -
12
13
14
15
\
\
10
\
ie
18
Fig. 3 Cluster
NATIONAL BUILDING CODE OF INDIA
2.27 <Cul-de-Sac' Cluster
Plots/dwelling units when located along a
pedestrianised or vehicular 'cul-de-sac' road (see
Fig. 4).
Fig. 4 Cul-de-Sac Cluster
2.28 Density — The residential density expressed in
terms of the number of dwelling units per hectare.
NOTE — Where such densities are expressed exclusive of
community facilities and provision of open spaces and major
roads (excluding incidental open spaces), these will be net
residential densities. Where these densities are expressed taking
into consideration the required open space provision and
community facilities and major roads, these would be gross
residential densities at neighbourhood level, sector level or
town level, as the case may be. The provision of open spaces
and community facilities will depend on the size of the
residential community.
Incidental open spaces are mainly open spaces required to be
left around and in between two buildings to provide lighting
and ventilation.
2.29 Detached Building — A building detached on
all sides.
230 Development — 'Development' with grammatical
variations means the carrying out of building,
engineering, mining or other operations, in, or over,
or under land or water, on the making of any material
change, in any building or land, or in the use of any
building, land, and includes re-development and layout
and subdivision of any land and 'to develop' shall be
construed accordingly.
2.31 Drain — A conduit, channel or pipe for the
carriage of storm water, sewage, waste water or other
water borne wastes in a building drainage system.
2.32 Drainage — The removal of any liquid by a
system constructed for the purpose.
2.33 Dwelling Unit/Tenement — An independent
housing unit with separate facilities for living, cooking
and sanitary requirements.
2.34 Escalator — A power driven, inclined, continuous
stairway used for raising or lowering passengers.
2.35 Exit — A passage, channel or means of egress
from any building, storey or floor area to a street or
other open space of safety.
2.36 External Faces of Cluster — Building edges
facing the cluster open spaces.
2.37 Fire Separation — The distance in metres
measured from the external wall of the building
concerned to the external wall of any other building
on the site, or from other site, or from the opposite
side of a street or other public space for the purpose of
preventing the spread of fire.
2.38 Floor — The lower surface in a storey on which
one normally walks in a building. The general term
'floor' unless specifically mentioned otherwise shall
not refer to a 'mezzanine floor'.
2.39 Floor Area Ratio (FAR) — The quotient
obtained by dividing the total covered area (plinth area)
on all floors by the area of the plot:
FAR =
Total covered area of the floors
Plot area
2.40 Gallery — An intermediate floor or platform
projecting from a wall of an auditorium or a hall
providing extra floor area, additional seating
accommodation, etc. It shall also include the structures
provided for seating in stadia.
2.41 Garage, Private — A building or a portion
thereof designed and used for parking of private owned
motor driven or other vehicles.
2.42 Garage, Public — A building or portion thereof,
other than a private garage, designed or used for
repairing, servicing, hiring, selling or storing or parking
motor driven or other vehicles.
2.43 Group Housing — Housing for more than one
dwelling unit, where land is owned jointly (as in the
case of co-operative societies or the public agencies,
such as local authorities or housing boards, etc) and
the construction is undertaken by one Agency.
2.44 Group Open Space — Open space within a
cluster.
Group open pace is neither public open space nor
private open space. Each dwelling unit around the
cluster open space have a share and right of use in it.
The responsibility for maintenance of the same is to
be collectively shared by all the dwelling units around.
2.45 Habitable Room — A room occupied or
designed for occupancy by one or more persons for
study, living, sleeping, eating, kitchen if it is used as a
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
living room, but not including bathrooms, water-closet
compartments, laundries, serving and store pantries,
corridors, cellars, attics, and spaces that are not used
frequently or during extended periods.
2.46 Independent Cluster — Clusters surrounded
from all sides by vehicular access roads and/or
pedestrian paths {see Fig. 5).
Fig. 5 Independent Cluster
2.47 Interlocking Cluster — Clusters when joined
at back and on sides with at least one side of a cluster
common and having some dwelling units opening onto
or having access from the adjacent clusters.
Dwelling units in such clusters should have at least
two sides open to external open space. Houses in an
interlocking cluster can have access, ventilation and
light from the adjacent cluster and should also cater
for future growth {see Fig. 6).
2.48 Internal Faces of Cluster — Building edges
facing the adjacent cluster open space (as in case of
interlocking cluster) of the surrounding pedestrian
paths or vehicular access roads.
2.49 Ledge or TAND — A shelf-like projection,
supported in any manner whatsoever, except by means
of vertical supports within a room itself but not having
projection wider than 1 m.
2.50 Lift — An appliance designed to transport
persons or materials between two or more levels in a
vertical or substantially vertical direction by means of
a guided car or platform. The word 'elevator' is also
synonymously used for 'lift'.
2.51 Loft — A structure providing intermediate
storage space in between two floors with a maximum
height of 1.5 m, without having a permanent access.
2.52 Mezzanine Floor — An intermediate floor
between two floors of any storey forming an integral
part of floor below.
2.53 Occupancy or Use Group — The principal
occupancy for which a building or a part of a building
is used or intended to be used; for the purposes of
classification of a building according to occupancy;
an occupancy shall be deemed to include subsidiary
occupancies which are contingent upon it.
2.54 Occupancy, Mixed — The occupancy, where
more than one occupancy are present in different
portions of-the building.
2.55 Open Clusters — Cluster where cluster open
spaces are linked to form a continuous open space {see
Fig. 7).
2.56 Open Space — An area, forming an integral part
of the plot, left open to the sky.
NOTE — The open space shall be the minimum distance
measured between the front, rear and side of the building and
the respective plot boundaries.
2.57 Open Space, Front — An open space across the
front of a plot between the building line and front
boundary of the plot.
2.58 Open Space, Rear — An open space across the
rear of a plot between the rear of the building and the
rear boundary of the plot.
2.59 Open Space, Side — An open space across the
side of the plot between the side of the building and
the side boundary of the plot.
Fig. 6 Interlocking Cluster
10
NATIONAL BUILDING CODE OF INDIA
lTjv ? i'M ;
". * . V..V.VH-;
W
.fey
.;V:rJ-.*.'">"
H:> '•;**? '?r'
..^■^^','v
;■;■:>>
r- lS '"" ; '-/'-, '' '
Fig. 7 Open Cluster
2.60 Owner — Person or body having a legal interest
in land and/or building thereon. This includes free
holders, leaseholders or those holding a sub-lease
which both bestows a legal right to occupation and
gives rise to liabilities in respect of safety or building
condition.
In case of lease or sub-lease holders, as far as ownership
with respect to the structure is concerned, the structure
of a flat or structure on a plot belongs to the allottee/
lessee till the allotment/lease subsists.
2.61 Parapet — A low wall or railing built along the
edge of a roof or floor.
2.62 Parking Space — An area enclosed or unenclosed,
covered or open, sufficient in size to park vehicles,
together with a drive- way connecting the parking space
with a street or alley and permitting ingress and egress
of the vehicles.
2.63 Partition — An interior non-load bearing barrier,
one storey or part-storey in height.
2.64 Plinth — The portion of a structure between the
surface of the surrounding ground and surface of the
floor, immediately above the ground.
2.65 Plinth Area — The built up covered area
measured at the floor level of the basement or of any
storey.
2.66 Porch — A covered structure supported on
pillars or otherwise for the purpose of pedestrian or
vehicular approach to a building.
2.67 Road — See 2.82.
2.68 Road Line — See 2.84.
2.69 Room Height — The vertical distance measured
from the finished floor surface to the finished ceiling
surface. Where a finished ceiling is not provided, the
underside of the joists or beams or tie beams shall
determine the upper point of measurement.
2.70 Row Housing/Row Type Building — A row of
buildings, with only front, rear and interior open spaces
where applicable.
2.71 Semi-Detached Building — A building detached
on three sides.
2.72 Service Road/Lane — A road/lane provided
adjacent to a plot(s) for access or service purposes as
the case may be.
2.73 Set-Back Line — A line usually parallel to the
plot boundaries and laid down in each case by the
Authority, beyond which nothing can be constructed
towards the plot boundaries.
2.74 Site (Plot) — A parcel (piece) of land enclosed
by definite boundaries.
2.75 Site, Corner — A site at the junctions of and
fronting on two or more intersecting streets.
2.76 Site, Depth of — The mean horizontal distance
between the front and rear site boundaries.
2.77 Site, Double Frontage — A site, having a
frontage on two streets, other than a corner plot.
2.78 Site, Interior or Tandem — A site access to
which is by a passage from a street whether such
passage forms part of the site or not.
2.79 Staircover (or MUMTY) — A structure with a
roof over a staircase and its landing built to enclose
only the stairs for the purpose of providing protection
from weather and not used for human habitation.
2.80 Storey — The portion of a building included
between the surface of any floor and the surface of the
floor next above it, or if there be no floor above it,
then the space between any floor and the ceiling next
above it.
2.81 Storey, Topmost — The uppermost storey in a
building whether constructed wholly or partly on the
roof.
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
11
2.82 Street — Any means of access, namely,
highway, street, lane, pathway, alley, stairway,
passageway, carriageway, footway, square, place or
bridge, whether a thoroughfare or not, over which the
public have a right of passage or access or have passed
and had access uninterruptedly for a specified period,
whether existing or proposed in any scheme, and
includes all bunds, channels, ditches, storm-water
drains, culverts, sidewalks, traffic islands, roadside
trees and hedges, retaining walls, fences, barriers and
railings within the street lines.
2.83 Street Level or Grade — The officially
established elevation or grade of the central line of the
street upon which a plot fronts and if there is no
officially established grade, the existing grade of the
street at its mid-point.
2.84 Street Line
of a street.
■ The line defining the side limits
2.85 To Abut — To abut on a street boundary such
that any portion of the building is on the road boundary .
2.86 To Erect — To erect a building means:
a) to erect a new building on any site whether
previously built upon or not; and
b) to re-erect any building of which portions
above the plinth level have been pull down,
burnt or destroyed.
2.87 Tower-like Structures — Structures shall be
deemed to be tower-like structures when the height of
the tower-like portion is at least twice the height of the
broader base at ground level.
2.88 VERANDAH — A covered area with at least one
side open to the outside with the exception of 1 m high
parapet on the upper floors to be provided on the open
side.
2.89 Volume to Plot Area Ratio (VPR) — The ratio
of volume of building measured in cubic metres to the
area of the plot measured in square metres and
expressed in metres.
2.90 Water-Closet (WC) — A water flushed
plumbing fixture designed to receive human excrement
directly from the user of the fixture. The term is used
sometimes to designate the room or compartment in
which the fixture is placed.
2.91 Window — An opening to the outside other than
a door, which provides all or part of the required natural
light or ventilation or both to an interior space.
3 LAND USE CLASSIFICATION AND USES
PERMITTED
3.1 Land Use Classification
The land use classification may be as indicated
below:
SI No. Use Zone (Level 1)
(1) (2)
Use Zone (Level 2)
(3)
i) Residential (R)
ii) Commercial (C)
iii) Manufacturing (M)
iv) Public and Semi-Public (PS)
v) Recreational (P)
Primary Residential Zone (R-l)
Mixed Residential Zone (R-2)
Unplanned/Informal Residential Zone (R-3)
Retail Shopping Zone (C-l)
General Business and Commercial District/Centres (C-2)
Wholesale, Godowns, Warehousing/Regulated Markets (C-3)
Service and Light Industry (M-l)
Extensive and Heavy Industry (M-2)
Special Industrial Zone Hazardous, Noxious and Chemical (M-3)
Government/Semi-Government/Public Offices (PS- 1 )
Government Land (use determined) (PS-2)
Educational and Research (PS-3)
Medical and Health (PS-4)
Social, Cultural and Religious (PS-5)
Utilities and Services (PS-6)
Cremation and Burial Grounds (PS-7)
Playgrounds/Stadium/Sports Complex (P-l)
Parks and Gardens — Public Open Spaces (P-2)
Special Recreational Zone — Restricted Open Spaces (P-3)
Multi-Open Space (Maidan) (P-4)
12
NATIONAL BUILDING CODE OF INDIA
SI No. Use Zone (Level 1)
(1) (2)
Use Zone (Level 2)
(3)
vi) Transportation and
Communication (T)
vii) Agriculture and Water Bodies
viii) Special Area
Roads (T-l)
Railways (T-2)
Airport (T-3)
Seaports and Dockyards (T-4)
Bus Depots/Truck Terminals and Freight Complexes (T-5)
Transmission and Communication (T-6)
Agriculture (A-l)
Forest (A-2)
Poultry and Dairy Farming (A-3)
Rural Settlements (A-4)
Brick Kiln and Extractive Areas (A-5)
Water Bodies (A-6)
Old Built-up (Core) Area (S-l)
Heritage and Conservation Areas (S-2)
Scenic Value Areas (S-3)
Village Settlement (S-4)
Other Uses (S-5)
NOTES
1 Areas of informal activities may be identified in the above land use categories at Level 2.
2 Mixed use zone may be identified at the development plan level, having more than one use zone with mixed activities of
such use zones.
3 In all, there could be 35 use zones at the development plan level within eight land use categories at the perspective plan
level as given in the above table.
4 Use premises for different activities could be provided at the project/action plan level or with the approval of the Authority
as the case may be.
5 Use zone regulations for the use permissibility could be decided by the town planner depending upon the requirement/
feasibility.
3.2 The various building uses and occupancies (see 7)
permitted on the various zones shall be as given in the
Master Plan.
3.3 Uses to be in Conformity with the Zone
Where the use of buildings or premises is not
specifically designated on the Development Plan or in
the absence of Development Plan, shall be in
conformity with the zone in which they fall.
3.4 Uses as Specifically Designated on Development
Plan
Where the use of a site is specifically designated on
the Development Plan, it shall be used only for the
purpose so designated.
3.5 Non-conforming Uses
No plot shall be put to any use, occupancy or premises
other than the uses identified in 3.1, except with the
prior approval of the Authority.
3.6 Fire Safety
Buildings shall be so planned, designed and constructed
as to ensure fire safety and this shall be done as per
Part 4 Tire and Life Safety'.
4 MEANS OF ACCESS
4.1 Every building/plot shall abut on a public/private
means of access like streets/roads duly formed.
4.2 Every person who erects a building shall not at
any time erect or cause or permit to erect any building
which in any way encroaches upon or diminishes the
area set apart as means of access required in the Code.
No buildings shall be erected so as to deprive any other
building of the means of access.
4.3 Width of Means of Access
The residential plots shall abut on a public means of access
like street/road. Plots which do not abut on a street/road
shall abut/front on a means of access, the width and other
requirements of which shall be as given in Table 1.
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
13
Table 1 Width and Length of Means of Access
(Clause 4.3)
SI
Width of Means
Length of Means
No.
of Access
of Access
m
m
(1)
(2)
(3)
i)
6.0
75
ii)
7.5
150
iii)
9.0
250
iv)
12.0
400
v)
18.0
1000
vi)
24.0
above 1 000
NOTE-
— If the development is only
on one side of the means of
access, the prescribed widths may be reduced by 1 m in each case.
In no case, development on plots shall be permitted
unless it is accessible by a public street of width not
less than 6 m.
4.3.1 Other Buildings
For all industrial buildings, theatres, cinema houses,
assembly halls, stadia, educational buildings, markets,
other buildings which attract large crowd, the means
of access shall not be less than the following:
Width of Means of
Length of Means
Access
of Access
m
m
12.0
200
15.0
400
18.0
600
24.0
above 600
Further, in no case shall the means of access be lesser
in width than the internal accessways in layouts and
subdivision.
4.3.2 Pathways
The approach to the buildings from road/street/internal
means of access shall be through paved pathway of
width not less than 1.5 m, provided its length is not
more than 30 m.
4.3.2.1 In the case of special housing schemes for low
income group and economically weaker section of
society developed up to two storeyed row/cluster
housing scheme, the pedestrian pathway width shall
be 3 m subject to provisions of 9.4.1(a). The pedestrian
pathway shall not serve more than 8 plots on each side
of the pathway; the length of the pathway shall be not
more than 50 m.
4.3.3 The length of the main means of access shall
be determined by the distance from the farthest plot
(building) to the public street. The length of the
subsidiary accessway shall be measured from the
point of its origin to the next wider road on which it
meets.
4.3.4 In the interest of general development of an area,
the Authority may require the means of access to be of
larger width than that required under 4.3 and 4.3.1.
4.3.5 In existing built-up areas in the case of plots
facing street/means of access less than 4.5 m in width,
the plot boundary shall be shifted to be away by 2.25 m
from the central line of the street/means of accessway
to give rise to a new street/means of accessway of 4.5 m
width.
4.4 The means of access shall be levelled, metalled,
flagged, paved, sewered, drained, chanelled, lighted,
laid with water supply line and provided with trees for
shade to the satisfaction of the Authority free of
encroachment by any structure or fixture so as not to
reduce its width below the minimum required under 4.3
and shall be maintained in a condition to the satisfaction
of the Authority.
44.1 If any private street or any other means of access
to a building is not levelled, metalled, flagged or paved,
sewered, drained, channelled, lighted or laid with water
supply line or provided with trees for shade to the
satisfaction of the Authority, who may, with the sanction
of the Authority, by written notice require the owner or
owners of the several premises fronting or adjoining the
said street or other means of access or abutting thereon
or to which access is obtained through such street or
other means of access or which shall benefit by works
executed, to carry out any or more of the aforesaid
requirements in such manner as he shall direct.
4.4.2 If any structure or fixture is set upon a means of
access so as to reduce its width below the minimum
required, the Authority may remove the same further
and recover the expenses so incurred from the owner.
4.5 Access from Highways/Important Roads
No premises other than highway amenities like petrol
pumps, motels, etc, shall have an access direct from
highways and such other roads not less than 52 m in
width, which the Authority with the approval of the
Highway Authority shall specify from time-to-time.
The Authority shall maintain a register of such roads
which shall be open to^public inspection at all times
during office hours. The portion of such roads on which
direct access may be permitted shall be as identified in
the Development Plan. However, in the case of existing
development on highways/other roads referred to
above, the operation of this clause shall be exempted.
These provisions shall, however, be subject to the
provisions of the relevant State Highway Act, and
National Highway Act.
4.6 For high rise buildings and buildings other than
residential, the following additional provisions of
means of access shall be ensured:
14
NATIONAL BUILDING CODE OF INDIA
a) The width of the main street on which the
building abuts shall not be less than 12m and
one end of this street shall join another street
not less than 12 m in width;
b) The approach to the building and open spaces
on all its sides up to 6 m width and the layout
for the same shall be done in consultation with
the Chief Fire Officer of the city and the same
shall be hard surface capable of taking the
mass of fire engine, weighing up to 45 tonnes.
The said open space shall be kept free of
obstructions and shall be motorable.
c) The main entrance to the plot shall be of
adequate width to allow easy access to the fire
engine and in no case shall it measure less than
6 m. The entrance gate shall fold back against
the compound wall of the premises, thus
leaving the exterior accessway within the plot
free for movement of fire service vehicle. If
the main entrance at the boundary wall is built
over, the minimum clearance shall be 4.5 m.
A turning radius of 9 m shall be provided for
fire tender movement.
4.7 Cul-de-sacs giving access to plots and extending
from 150 m to 275 m in length with an additional
turning space at 150 m will be allowed only in
residential areas, provided cul-de-sacs would be
permissible only on straight roads and further provided
the end of cul-de-sacs shall be higher in level than the
level of the starting point of such dead end road. The
turning space, in this case shall be not less than 81 m 2
in area, with no dimension less than 9 m.
4.8 Intersection of Roads
For intersection junctions of roads meeting at right
angles as well as other than right angles, the rounding
off or cut off or splay or similar treatment shall be
done, to the approval of the Authority, depending upon
the width of roads, the traffic generated, the sighting
angle, etc, to provide clear sight distance.
4.9 The building line shall be set back at least 3 m
from internal means of access in a layout of buildings
in a plot subject to provisions of 8.2.1.
5 COMMUNITY OPEN SPACES AND AMENITIES
5.1 Residential and Commercial Zones
In any layout or sub-division of land measuring 0.3
hectare of more in residential and commercial zones,
the community open spaces shall be reserved for
recreational purposes which shall as far as possible be
provided in one place or planned out for the use of the
community in clusters or pockets.
5.1,1 The community open spaces shall be provided
catering to the needs of area of layout, population for
which the layout is planned and the category of
dwelling units. The following minimum provision shall
be made:
a) 15 percent of the area of the layout, or
b) 0.3 to 0.4 ha/1 000 persons; for low income
housing the open spaces shall be 0.3 ha/1 000
persons.
5.2 No recreational space shall generally be less than
450 m 2 .
5.2.1 The minimum average dimension of such
recreational space shall be not less than 7.5 m; if the
average width of such recreational space is less than
24 m, the length thereof shall not exceed 2.5 times
the average width. However, depending on the
configuration of the site, commonly open spaces of
different shapes may be permitted by the Authority, as
long as the open spaces provided serve the needs of the
immediate community contiguous to the open spaces.
5.2.2 In such recreational spaces, a single storeyed
structure as pavilion or gymnasia up to 25 m 2 in area
may be permitted; such area may be excluded from
FAR calculations.
5.3 Each recreational area and the structure on it shall
have an independent means of access. Independent
means of access may not be insisted upon if
recreational space is approachable directly from every
building in the layout. Further, the building line shall
be at least 3 m away from the boundary of recreational
open space.
5.4 Industrial Zones
In the case of sub-division of land in industrial zones
of area 0.8 hectare or more, 5 percent of the total area
shall be reserved as amenity open space which shall
also serve as a general parking space; when such
amenity open space exceeds 1 500 m 2 , the excess area
could be utilized for the construction of buildings for
banks, canteens, welfare centres and such other
common purposes considered necessary for the
industrial user, as approved by the Authority.
5.4.1 In all industrial plots measuring 1 000 m 2 or more
in area, 10 percent of the total area shall be provided as
an amenity open space to a maximum of 2 500 m 2 . Such
an amenity open space shall have a means of access and
shall be so located that it could be conveniently utilized
as such by the persons working in the industry.
5.5 Other Amenities
In addition to community open spaces, the layouts shall
provide for the amenities as given in 5.5.1 to 5.5.6.
These provisions may be modified based on specific
requirements, as decided by the Authority.
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
15
5.5.1 Educational Facilities
Land Area Required, Min
a) Pre-Primary to Secondary Education
1) Pre-primary, nursery school (1 for every 2 500 population)
i) Area per school 0.08 ha
ii) Location of pre-primary/nursery school Near a park
2) Primary school (class 1 to 5) (1 for every 5 000 population)
i) Strength of school — 500 students
ii) Area per school 0.40 ha
a) School building area 0.20 ha
b) Play field area (with a minimum of 18 m x 36 m to be ensured for effective play) 0.20 ha
3) Senior secondary school (class 6 to 12) (1 for every 7 500 population)
° i) Strength of the school — 1 000 students
ii) Area per school 1.80 ha
a) School building area 0.60 ha
b) Play field area (with a minimum of 68 m x 126 m to be ensured for effective play) 1.00 ha
c) Parking area 0.20 ha
4) Integrated school without hostel facility (class 1 to 12) (1 for every 90 000 to 100 000
population)
i) Strength of the school — 1 500 students
ii) Area per school 3.50 ha
a) School building area 0.70 ha
b) Play field area 2.50 ha
c) Parking 0.30 ha
5) Integrated school with hostel facilities (class 1 to 12) (1 for every 90 000 to 100 000
population)
i) Strength of school — 1 500 students
ii) Area per school 3.90 ha
a) School building area 0.70 ha
b) Play field area 2.50 ha
c) Residential (including hostel area) 0.40 ha
d) Parking area 0.30 ha
6) School for physically challenged (class 1 to 12) (1 for every 45 000 population)
i) Strength of school — 400 students
ii) Area per school 0.70 ha
a) School building area 0.20 ha
b) Play field area 0.30 ha
c) Parking area 0.20 ha
b) Higher Education — General
1) College (1 for every 125 000 population)
i) Student strength of college — 1 000 to 1 500 students
ii) Area per college 5.00 ha
a) College building area 1.80 ha
b) Play field area 2.50 ha
c) Residential (including hostel area) 0.40 ha
d) Parking area 0.30 ha
2) University campus/centre area 10.00 ha
3) New university area 60.00 ha
16 NATIONAL BUILDING CODE OF INDIA
Land Area Required, Min
c) Technical Education
1) Technical education centre (A) (1 for every 1 000 000 population to include 1 ITI and
1 polytechnic)
i) Strength of ITI — 400 students
ii) Strength of polytechnic — 500 students
iii) Area per technical education centre
a) Area for ITI
b) Area for polytechnic
2) Technical education centre (B) (1 for every 1 000 000 population to include 1 ITI y
1 technical centre and 1 coaching centre)
Area per technical education centre
a) Area for ITI
b) Area for technical centre
c) Area for coaching centre
d) Professional Education
1) Engineering college (1 for every 1 000 000 population)
i) Strength of the college — 1 500 students
ii) Area per college 6.00 ha
2) Medical college (1 for every 1 000 000 population)
Area of site including space for general hospital 15.00 ha
3) Other professional colleges (1 for every 1 000 000 population)
i) Area of site for students strength upto 250 students 2.00 ha
ii) Additional area of site for every additional 100 students or part thereof upto
total strength of 1 000 students 0.50 ha
iii) Area of site for strength of college — From 1 000 to 1 500 students 6.00 ha
4.00 ha
1.60 ha
2.40 ha
4.00 ha
1.60 ha
2.10 ha
0.30 ha
5.5.2 Health Care Facilities
1) Dispensary (1 for every 15 000 population)
Area
2) Nursing home, child welfare and maternity centre (1 for every 45 000 to
100 000 population)
i) Capacity 25 to 30 beds
ii) Area
3) Poly-clinic with some observation beds (1 for every 100 000 population)
Area
4) Intermediate hospital (category B) (1 for every 100 000 population)
i) Capacity 80 beds (initially the provision may be for 50 including 20 maternity
beds)
ii) Total area
a) Area for hospital
b) Area for residential accommodation
5) Intermediate hospital (category A) (1 for every 100 000 population)
i) Capacity 200 beds (initially the provision may be for 100 beds)
ii) Total area
a) Area for hospital
b) Area for residential accommodation
Land Area Required, Min
0.08 ha to 0.12 ha
0.20 ha to 0.30 ha
0.20 ha to 0.30 ha
1.00 ha
0.60 ha
0.40 ha
3.70 ha
2.70 ha
1.00 ha
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
17
Land Area Required, Min
6) General hospital (1 for every 250 000 population)
i) Capacity 500 beds (initially the provision may be for 300 beds)
ii) Total area 6.00 ha
a) Area for hospital 4.00 ha
b) Area for residential accommodation 2.00 ha
7) Multi-speciality hospital (1 for 100 000 population)
i) Capacity 200 beds (initially the provision may be for 100 beds)
ii) Total area 9.00 ha
a) Area for hospital 6.00 ha
b) Area for residential accommodation 3.00 ha
8) Speciality hospital (1 for every 100 000 population)
i) Capacity 200 beds (initially the provision may be for 100 beds)
ii) Total area 3.70 ha
a) Area for hospital 2.70 ha
b) Area for residential accommodation 1.00 ha
5.5.3 Socio-cultural facilities
Land Area Required, Min
1) Community room (1 for every 5 000 population)
Area 750 m 2
2) Community hall, mangal karyayala/kalyana mandapam/barat ghar/library
(1 for every 15 000 population)
Area 2 000 m 2
3) Recreational club (1 for every 100 000 population) (see also 5.2, 5.2.1, 5.2.2 and 5.3)
Area 10 000 m 2
4) Music, dance and drama centre (1 for every 100 000 population)
Area 1 000 m 2
5) Meditation and spiritual centre (1 for every 100 000 population)
Area 5 000 m 2
6) Socio-cultural centre (1 for every 1 000 000 population)
Area 15 ha
5.5.4 Distribution Services
Land Area Required, Min
1) Petrol/diesel filling and servicing centre
May be permitted in central as well as sub-central business district, district centres,
community centres (only filling station), residential and industrial use zones in urban
areas, along the national highways, state highways, villages identified as growth centres,
freight complex and on proposed major roads.
Shall not be located on the road having right of way less than 30 m.
Shall be approved by the explosive/fire department.
Area/Size
i) Only filling station 30 m x 17 m
ii) Filling-cum-service station 36 m x 30 m
iii) Filing-cum-service station-cum-workshop 45 m x 36 m
iv) Filling station only for two and three wheelers 18 m x 15 m
2) Compressed natural gas (CNG)/filling centre
Permitted in all use zones (except in regional parks and Developed District Parks) and
along the national highways, state highways and villages identified as growth centres,
freight complex and on proposed major roads
18 NATIONAL BUILDING CODE OF INDIA
Land Area Required y Min
Shall not be located on the road having right of way less than 30 m.
Shall be approved by the explosive/fire department.
Area/size for mother station (building component — control room/office/dispensing 1 080 m 2
room, store, pantry and W.C. (36 m x 30 m)
3) LPG godowns/Gas godown 1 for every 40 000 to 50 000 population
The major concern for its storage and distribution is the location which shall be away
from the residential areas and shall have open spaces all around as per the Explosive
Rules.
i) Capacity — 500 cylinders or 8 000 kg of LPG 520 m 2
ii) Area (inclusive of chowkidar hut) (26 m x 20 m)
4) Milk distribution (1 milk booth for every 5 000 population)
Area inclusive of service area 150 m 2
5.5.5 Police, Civil Defence and Home Guards
Land Area Required, Min
1) Police station (1 for every 90 000 population)
Area (inclusive of essential residential accommodation 0.05 ha additional to be 1.50 ha
provided for civil defence and home guards)
2) Police post (1 for every 40 000 to 50 000 population) (not served by a police station)
Area (inclusive of essential residential accommodation) 0.16 ha
3) District office and battalion (1 for every 1 000 000 population)
i) Area for district office 0.80 ha
ii) Area for battalion 4.00 ha
iii) Total area 4.80 ha
4) Police line (1 for every 2 000 000 population)
Area 4.00 to 6.00 ha
5) District Jail (1 for every 1 000 000 population)
Area 10.00 ha
6) Civil defence and home guards (1 for every 1 000 000 population)
Area 2.00 ha
5.5.6 Fire
Land Area Required, Min
One fire station or sub-fire station within 1 km to 3 km (for every 200 000 population)
i) Area for fire station with essential residential accommodation 1 .00 ha
ii) Area for sub-fire station with essential residential accommodation 0.60 ha
5.5.7 Telephone, Telegraphs, Postal and Banking Facilities
Land Area Required, Min
a) Telephone and Telegraphs
1) Telephone exchange of 40 000 lines (1 for every 400 000 population)
Area 4.00 ha
2) Telegraph booking counter (1 for every 100 000 population)
Floor area to be provided in community centre 200 m 2
3) Telegraph booking and delivery office (1 for every 500 000 population)
Floor area to be provided in district centres 1 700 m 2
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS 19
b) Postal
1) Post office counter without delivery (1 for every 15 000 population)
Floor area to be provided in local shopping centre
2) Head post office with delivery office (1 for 250 000 population)
Area
3) Head post office and administrative office (1 for 500 000 population)
Area
c) Banking
1) Extension counters with ATM facility (1 for every 15 000 population)
i) Floor area for counters
ii) Floor area for ATM
2) Bank with locker, ATM and other banking facilities (1 for 100 000 population)
Area
Land Area Required, Min
85 m 2
750 m 2
2 500 m 2
75 m 2
6 m 2
2 500 m 2
5.5.8 Sports Activity
1 ) Divisional sports centre (1 for 1 000 000 population)
Area
2) District sport centre (1 for 100 000 population)
Area
3) Neighbourhood play area (1 for 15 000 population)
Area
4) Residential unit play area (1 for 5 000 population)
Area
Land Area Required, Min
20.00 ha
8.00 ha
1.50 ha
5 000 m 2
5.5.9 Shopping
Land Area Required, Min
1500 m 2
4 600 m 2
5.00 ha
1 ) Convenience shopping (1 for 5 000 population)
Area
2) Local shopping including service centre (1 for 15 000 population)
Area
3) Community centre with service centre (1 for 100 000 population)
Area
4) District centre (1 at district level/1 for 500 000 population)
Area 7.50 ha
5) Local wholesale market (1 for 1 000 000 population)
Area 10.00 ha
6) Weekly markets (1 to 2 locations for every 100 000 populations with 300 to 400 units per
location)
Parking and other open spaces within the commercial centres could be so designed that
weekly markets can operate in these areas during non-working hours.
The area of informal sector should have suitable public conveniences and solid waste
disposal arrangements.
Area per location 0.40 ha
7) Organized informal sector eating places (1 for 100 000 population)
Area 2 000 m 2
20
NATIONAL BUILDING CODE OF INDIA
5.5.10 Religious
1) Religious campus (1 for 100 000 population)
Area
Land Area Required, Min
5.00 ha
5.5.11 Electrical Sub-station
1) 11 kV Substation (1 for 15 000 population)
Area
2) 66 kV Sub-station (2 for 100 000 population)
Area for each Sub-station
3) 220 kV Sub-station (1 for 500 000 population)
Area
Land Area Required, Min
500 m 2
6 000 m 2
(that is 60 m x 100 m)
4.00 ha
5.5.12 Transport
1) Three wheeler and taxi stand (1 for 15 000 population)
Area
2) Bus terminal (1 for 100 000 population)
Area
3) Bus depot (1 for 500 000 population)
Area
Land Area Required, Min
500 m 2
4 000 m 2
2.00 ha
5.5.13 Cremation/Burial Ground
The site shall be identified in locations, which are not proximous to residential areas
1) Electric crematorium (1 for large size towns)
Area
2) Cremation ground (1 for 500 000 population)
Area
3) Burial ground (1 for 500 000 population)
Area
Land Area Required, Min
2.00 ha
2.50 ha
4.00 ha
5.5.14 Dhobi Ghat
Land Area Required, Min
1) Dhobi ghat with appropriate arrangements for water and drainage facilities
and it shall be ensured that the water bodies are not polluted as a result of
such activities (1 for 100 000 population)
Area 5 000 m 2
5.6 Every layout or sub-division shall take into account 6 REQUIREMENTS OF PLOTS
the provisions of development plan and if the land is 61 No building shall be constructed on any site, on
affected by any reservation for public purposes, the any part of which mere is deposited refuse, excreta or
Authority may agree to adjust the location of such other offensive matter objectionable to the Authority,
reservations to suit the development.
until such refuse has been removed therefrom and the
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
21
site has been prepared or left in a manner suitable for
building purposes to the satisfaction to the Authority.
6.2 Damp Sites
Wherever the dampness of a site or the nature of the
soil renders such precautions necessary, the ground
surface of the site between the walls of any building
erected thereon shall be rendered damp-proof to the
satisfaction of the Authority.
6.3 Surface Water Drains
Any land passage or other area within the curtilage of
a building shall be effectively drained by surface water
drains or other means.
6.3.1 The written approval of the Authority shall be
obtained for connecting any sub-soil or surface water
drain to a sewer.
6.4 Distance from Electric Lines
No VERANDAH, balcony, or the like shall be allowed
to be erected or re-erected or any additions or alterations
made to a building within the distances quoted below in
accordance with the current Indian Electricity Rules as
amended from time-to-time between the building and
any overhead electric supply line:
corresponding to the type of development as given
below:
Vertically
Horizontally
m
m
(1) (2)
(3)
(4)
a) Low and medium
2.5
1.2
voltage lines and
service lines
b) High voltage lines up
to and including
1 1 000 V
3.7
1.2
c) High voltage lines
above 11 000 V and
3.7
2.0
up to and including
33 000 V
d) Extra high voltage
line beyond 33 000 V
3.7
(plus 0.3 m
2.0
(plus 0.3 m
for every
additional
for every
additional
33 000 V
or part
thereof)
33 000 V
or part
thereof)
6.5 Distance of site from the normal edge of water
course/area may be specified by the Authority, keeping
in view the normal maximum flood/tide level.
6.6 Size of Plots
6.6.1 Residential
Each plot shall have a minimum size/frontage
Type of Development
Plot Size
Frontage
m 2
m
(1)
(2)
(3)
Detached building Above 250 Above 12
Semi-detached building 125-250 8 to 12
Row type building 50-125 4.5 to 8
NOTE — For low income housing see 12.20.
6.6.1.1 The minimum size of the site for group housing
development shall be as given in the Master Plan and
local development control rules.
6.6.2 Industrial
The size of the plot shall not be less than 300 m 2 and
its width shall not be less than 15 m.
6.6.3 Other Land Uses
The minimum size of plots for buildings for other uses
not covered under 5.5 shall be as decided by the
Authority.
7 CLASSIFICATION OF BUILDINGS
7.0 Buildings are classified based on occupancy and
types of construction.
7.1 For the purpose of the Code, the following
shall be the occupancy classification and types of
construction; for more detailed information, reference
may be made to Part 4 'Fire and Life Safety'.
7.1.1 Occupancy Classification
a) Residential;
b) Educational;
c) Institutional;
d) Assembly;
e) Business;
f) Mercantile (will include both retail and
wholesale stores);
g) Industrial (will include low, moderate and
high fire hazards);
h) Storage; and
j) Hazardous.
7.1.2 Types of Construction
a) Type 1,
b) Type 2,
c) Type 3, and
d) Type 4.
22
NATIONAL BUILDING CODE OF INDIA
8 OPEN SPACES (WITHIN A PLOT)
8.1 General
Every room intended for human habitation shall abut
on an interior or exterior open space or an open
VERANDAH open to such interior or exterior open
space.
8.1.1 The open spaces inside and around a building
have essentially to cater for the lighting and ventilation
requirements of the rooms abutting such open spaces,
and in the case of buildings abutting on streets in the
front, rear or sides, the open spaces provided shall be
sufficient for the future widening of such streets.
8.1.2 Open Spaces Separate for each Building or Wing
The open spaces shall be separate or distinct for each
building and where a building has two or more wings,
each wing shall have separate or distinct open spaces
for the purposes of lighting and ventilation of the wings.
However, separation between accessory and main
buildings more than 7 m in height shall not be less
than 1.5 m; for buildings up to 7 m in height no such
separation shall be required.
8.1.3 The open space shall be the minimum distance
measured between the front, rear and side of the
building and the respective plot boundaries. The front,
rear and side of the building shall be the point of the
building nearest to the boundary.
8.2 Residential Buildings
8.2.1 Exterior Open Spaces
8.2.1.1 Front open space
a) Every building fronting a street shall have a
front space, forming an integral part of the
site as below:
SI
Front Open
Space,
Width of Street
No.
Min
Fronting the Plot
m
m
(1)
(2)
(3)
i)
1.5 1}
Upto7.5 1}
ii)
3.0
7.5 to 18
iii)
4.5
18 to 30
iv)
6.0
Above 30
For buildings up to a maximum height 7 m.
NOTE — In case a building abuts two or more streets, the
value of open paces is to be based on the average width of
streets, subject to a minimum of 1.8 m for cases (ii), (iii) and
(iv) above.
b) For streets less than 7.5 m in width, the
distance of the building (building line) shall
be at least 5 m from the centre line of the street
{see 4.3.5),
NOTE — This limiting distance has to be determined
by the Authority for individual road/street widths taking
into account the traffic flow.
8.2.1.2 Rear open space
a)
b)
c)
Every residential building shall have a rear
open space, forming an integral part of the
site, of an average width of 3 m and at no
place measuring less than 1.8 m, except that
in the case of a back-to-back sites, the width
of the rear open space shall be 3 m throughout.
Subject to the condition of free ventilation,
the open space left up to half the width of the
plot shall also be taken into account for
calculating the average width of the rear open
space. For plots of depths less than 9 m, for
buildings up to 7 m in height, the rear open
space may be reduced to 1.5 m.
Rear open space to extend the rear wall
The rear open space shall be co-extensive with
the entire face of the rear wall. If a building
abuts on two or more streets, such rear open
space shall be provided throughout the face
of the rear wall. Such rear wall shall be the
wall on the opposite side of the face of the
building abutting on the wider street unless
the Authority directs otherwise.
In case of corner plots less than 300 m 2 in
area, the rear open space should be 2.4 m
minimum.
8.2.1.3 Side open space
a) Every semi-detached and detached building
shall have a permanently open air space,
forming an integral part of the site as below:
1) For detached buildings there shall be a
minimum side open space of 3 m on both
the sides.
NOTE — For detached residential buildings up
to 7 m in height on plots with a frontage less than
12 m {see 6.6.1), one of the side open spaces may
be reduced to 1.5 m.
2) For semi-detached buildings, there shall
be a minimum side open space of 3 m on
one side.
NOTE — For semi-detached buildings up to 7 m
in height on plots with a frontage less than 9 m
{see 6.6.1), the side open spaces may be reduced
to 1.5 m.
3) For row-type buildings, no side open is
required.
b) In the case of semi-detached buildings, the
open spaces provided on one side shall be as
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
23
in 8.2.1.3 (a) and all habitable rooms shall
abut either on this side open space or front
and rear open spaces or an interior open space
(see 8.2.5).
8.2.2 The provisions of 8.2.1.2 and 8.2.1.3 are not
applicable to parking lock-up garages up to 3 m in
height located at a distance of 7.5 m from any street
line or front boundary of the plot.
8.2.3 The open spaces mentioned in 8.2.1.1 to 8.2.1.3
shall be for residential buildings up to a height of 10 m.
8.2.3.1 For buildings of height above 10 m, the open
spaces (side and rear) shall be as given in Table 2. The
front open spaces for increasing heights of buildings
shall be governed by 9.4.1 (a).
Table 2 Side and Rear Open Spaces for Different
Heights of Buildings
(Clause 8.2.3.1)
SI
Height of
Side and Rear Open Spaces to
No.
Buildings
be Left Around Building
m
m
(1)
(2)
(3)
i)
10
3
ii)
15
5
iii)
18
6
iv)
21
7
v)
24
8
vi)
27
9
vii)
30
10
viii)
35
11
ix)
40
12
x)
45
13
«)
50
14
xii)
55 and above
16
NOTES
1 For buildings above 24 m in height, there shall be a minimum
front open space of 6 m.
2 Where rooms do not derive light and ventilation from the
exterior open space, the width of such exterior open space as
given in col 3 may be reduced by 1 m subject to a minimum of
3 m and a maximum of 8 m. No further projections shall be
permitted.
3 If the length or depth of the building exceeds 40 m, add
to col (3) 10 percent of length or depth of building minus
4.0 m.
8.2.3.2 For tower-like structures, as an alternative
to 8.2.3.1, open spaces shall be as below:
a) Up to a height of 24 m, with one set-back, the
open spaces at the ground level, shall be not
less than 6 m;
b) For heights between 24 m and 37.5 m with
one set-back, the open spaces at the ground
level, shall be not less than 9 m;
c) For heights above 37.5 m with two set-backs,
the open spaces at the ground level, shall be
not less than 12 m; and
d) The deficiency in the open spaces shall be
made good to satisfy 8.2.3.1 through the set-
backs at the upper levels; these set-backs shall
not be accessible from individual rooms/flats
at these levels.
8.2.4 The front open space would govern the height
of the building (see 9.4).
8.2.5 Interior Open Spaces
a) Inner courtyard — In case the whole of one
side of every room excepting bath, WC and
store room is not abutting on either the front,
rear or side open spaces, it shall abut on an
inner courtyard, whose minimum width shall
be 3 m.
Further, the inner courtyard shall have an area,
throughout its height, of not less than the
square of one-fifth the height of the highest
wall abutting the courtyard. Provided that
when any room (excluding staircase bay,
bathroom and water-closet) is dependent for
its light and ventilation on an inner courtyard,
the dimension shall be such as is required for
each wing of the building.
Where only water-closet and bath room are
abutting on the interior courtyard, the size of
the interior courtyard shall be in line with the
provision for ventilation shaft as given
in 8.2.5 (b).
b) Ventilation shaft — For ventilating the spaces
for water-closets and bath rooms, if not
opening on to front, side, rear and interior
open spaces, these shall open on the
ventilation shaft, the size of which shall not
be less than the values given below:
Height of
Size of
Minimum
Buildings
Ventilation
One Dimension of
Shaft
the Shaft
m
m 2
m
(1)
(2)
(3)
Up to 10
1.2
0.9
12
2.8
1.2
18
4.0
1.5
24
5.4
1.8
30
8.0
2.4
Above 30
9.0
3.0
NOTES
1 For buildings of height above 30 m, a mechanical ventilation
system shall be installed besides the provision of minimum
ventilation shaft.
2 For fully air-conditioned residential buildings for lodging
purposes, the ventilation shaft need not be insisted upon,
provided the air-conditioning system works in an uninterrupted
manner, also, provided there is an alternative source of power
supply.
24
NATIONAL BUILDING CODE OF INDIA
c) Outer courtyard — The minimum width of
the outer courtyard (as distinguished from its
depth) shall be not less than 2.4 m. If the width
of the outer courtyard is less than 2.4 m, it
shall be treated as a notch and the provisions
of outer courtyard shall not apply. However,
if the depth of the outer courtyard is more than
the width, the provisions of 8.1.2 shall apply
for the open spaces to be left between the
wings.
8.2.6 Joint Open Air Space
Every such interior or exterior open air space, unless
the latter is a street, shall be maintained for the benefit
of such building exclusively and shall be entirely within
the owner's own premises.
8.2.6.1 If such interior or exterior open air space is
intended to be used for the benefit of more than one
building belonging to the same owner, the width of
such open air space shall be the one specified for the
tallest building as specified in 8.2.3 abutting on such
open air space.
8.2.6.2 If such interior or exterior open air space is
jointly owned by more than one person, its width shall
also be as specified in 8.2, provided every such person
agrees in writing to allow his portion of such joint open
air space to be used for the benefit of every building
abutting on such joint open air space and provided he
sends such written consent to the Authority for record.
Such common open air space shall thenceforth be
treated as a permanently open air space required for
the purposes of the Code. No boundary wall between
such joint open air space shall be erected or raised to a
height of more than 2.0 m.
8.3 Other Occupancies
8.3.1 Open spaces for other occupancies shall be as
below:
a) Educational buildings — Except for nursery
schools, the open spaces around the building
shall be not less than 6 m.
b) Institutional buildings — The open spaces
around the building shall be not less than 6 m.
c) Assembly buildings — The open space at front
shall be not less than 12 m and the other open
spaces around the building shall be not less
than 6 m.
NOTE — However, if assembly buildings are permitted
in purely residential zones, the open spaces around the
building shall be not less than 12 m.
d) Business, mercantile and storage buildings —
The open spaces around the building shall be
not less than 4.5 m. Where these occur in a
purely residential zone or in a residential with
shops line zone the open spaces may be
relaxed.
e) Industrial buildings — The open spaces
around the building shall be not less than
4.5 m for heights up to 16 m, with an increase
of the open spaces of 0.25 m for every
increase of 1 m or fraction thereof in height
above 16 m.
NOTE — Special rules for narrow industrial plots in
the city, namely plots less than 15 m in width, and with
appropriate set-backs from certain streets and highways,
shall be applicable.
f) Hazardous occupancies — The open spaces
around the building shall be as specified for
industrial buildings [see 8.3.1 (e)].
8.4 Exemption to Open Spaces
8.4.1 Projections into Open Spaces
Every open space provided either interior or exterior
shall be kept free from any erection thereon and shall
be open to the sky, except as below:
a) Cornice, roof or weather shade not more than
0.75 m wide;
b) Sunshades over windows/ventilators or other
openings not more than 0.75 m wide; #
c) Canopy not to be used as a sit out with
clearance of 1 .5 m between the plot boundary
and the canopy;
d) Projected balcony at higher floors of width
not more than 1.2 m; and
e) Projecting rooms/balconies [see (d)] at
alternate floors such that rooms of the lower
two floors get light and air and the projection
being not more than the height of the storey
immediately below.
However, these projections into open spaces shall not
reduce the minimum required open spaces.
8.4.1.1 Accessory building
The following accessory buildings may be permitted
in the open spaces:
a) In an existing building, sanitary block of
2.4 m in height subject to a maximum of 4 m 2
in the rear open space at a distance of 1 .5 m
from the rear boundary may be permitted,
where facilities are not adequate.
b) Parking lock up garages not exceeding 2.4 m
in height shall be permitted in the side or
rear open spaces at a distance of 7.5 m from
any road line or the front boundary of the plot;
and
c) Suction tank and pump room each up to
2.5 m 2 in area.
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
25
8.4.2 Projection into Street
8.4.2.1 In existing built-up or congested areas, no
projection of any sort whatsoever, except sunshades
{see 8.4.2.3) extending more than 23 cm below a height
of 4.3 m, shall project over the road or over any drain
or over any portion outside the boundaries of the site,
provided the projection arising out of the vertical part
of the rain-water spouts projecting at the road level or
the water pipe may be permitted in accordance with
the drainage plan.
8.4.2.2 Porticos in existing developed area
Porticos in bazaar areas of existing developed areas
may be permitted to project on road land subject to the
following limitations:
a) Porticos may be allowed on such roads
leaving a minimum clear space of 18 m
between kerbs;
b) The porticos shall not be less than 3 m wide;
c) Nothing shall be allowed to be constructed
on the portico which shall be used as an open
terrace;
d) Nothing shall be allowed to project beyond
the line of arcades; and
e) The space under the portico shall be paved
and channelled according to the directions of
the Authority.
8.4.2.3 Sunshades over windows and ventilators
Projections of sunshades over windows or ventilators
in existing built-up or congested areas when permitted
by the Authority shall fulfil the following conditions:
a) No sunshade shall be permitted over the road
or over any drain or over any portion outside
the boundaries of the site below a height of
2.8 m from the road level;
b) Sunshades provided above a height of 2.8 m
from the ground level shall be permitted to
project up to a maximum width of 60 cm, if
the road over which they project exceeds 9 m
in width; and
c) No sunshade shall be permitted on roads less
than 9 m in width or on roads having no
footpaths.
8.5 Limitations to Open Spaces
8.5.1 Safeguard Against Reduction of Open Space
No construction work on a building shall be allowed
if such work operates to reduce an open air space of
any other adjoining building, belonging to the same
owner to an extent less than what is prescribed at the
time of the proposed work or to reduce further such
open space if it is already less than that prescribed.
8.5.2 Additions or Extensions to a Building
Additions or extensions to a building shall be allowed,
provided the open spaces for the additions/extensions
satisfy 8.2 after such additions/extensions are made.
9 AREA AND HEIGHT LIMITATIONS
9.1 General
The limitation of area and height of buildings of
different occupancy classes and types of construction
shall be achieved by specifying it in terms of FAR,
which shall take into account the various aspects that
govern in specifying FAR as given below:
a) Occupancy class;
b) Types of construction;
c) Width of street fronting the building and the
traffic load;
d) Locality where the building is proposed and
the density;
e) Parking facilities;
f) Local fire fighting facilities; and
g) Water supply and drainage facilities.
9.2 The comparative FAR's for different occupancies
and types of construction are as given in Table 3 and
the Authority shall select a basic FAR for one
occupancy and a type of construction and arrive at the
FAR values for other combinations taking into account
the other local factors (see 9.1).
9.2.1 Unlimited Areas
The minimum fire separation on all sides of buildings
of unlimited areas (see Table 3) and of Type 1
construction shall be 9 m.
9.3 Street Width
The area limits shall apply to all buildings fronting on
a street or public space not less than 9 m in width
accessible to a public street.
9.4 Height Limit
The height and number of storeys shall be related to
FAR and the provisions of 8.
9.4.1 Where a building height is not covered by
Table 3, the maximum height shall be limited
according to the width of the street as follows:
a) The maximum height of building shall not
exceed 1 .5 times the width of road abutting
plus the front open space;
b) If a building abuts on two or more streets of
different widths, the building shall be deemed
to face upon the street that has the greater
width and the height of the building shall be
26
NATIONAL BUILDING CODE OF INDIA
Table 3 Comparative Floor Area Ratios for
Occupancies Facing One Public Street
of at Least 9 m Width
(Clauses 2.26, 9.2 and 9.2.1)
Occupancy
Type of Construction
Classification
^^s^
Typel
Type 2
Type 3
— V
Type 4
(1)
(2)
(3)
(4)
(5)
Residential
UL
2.0
1.4
1.0
Educational
UL
2.0
1.4
1.0
Institutional
UL
1.5
1.0
0.8
Assembly
UL
1.0
0.7
0.5
Business
UL
2.9
2.3
1.6
Mercantile
8.0
1.8
1.4
1.0
Industrial
7.5
1.9
1.6
1.3
Storage
6.0
.1.5
1.3
1.0
(see Note 4)
Hazardous
2.8
1.1
0.9
NP
(see Note 4)
UL — Unlimited
NP — Not Permitted
NOTES
1 This table has been prepared, taking into account the
combustible content in the different occupancies as well as
the fire resistance offered by the type of construction (see Part 4
'Fire and Life Safety').
2 This table shall be modified by the Authority, taking into
account the other aspects as given below (see 9.1):
a) Density in terms of dwelling units/hectare;
b) Traffic considerations;
c) Parking spaces;
d) Local fire fighting facilities; and
e) Water supply, drainage and sanitation requirements.
3 The FAR specified may be increased by 20 percent for the
following:
a) A basement or cellar and space under a building
constructed on stilts and used as a parking space, and air-
conditioning plant room used as accessory to the principal
use;
b) Electric cabin or sub-station, watchman's booth of
maximum size of 1.6 m 2 with minimum width or diameter
of 1.2 m, pumphouse, garbage shaft, space required for
location of fire hydrants, electric fittings and water tank;
c) Projections and accessory buildings as specifically
exempted (see 8.4.1); and
d) Staircase room and lift rooms above the topmost storey,
architectural features; and chimneys and elevated tanks of
dimensions as permissible under the Code; the area of the
lift shaft shall be taken only on one floor.
4 In so far as single storey storage and hazardous occupancies
are concerned, they would be further governed by volume to
plot area ratio (VPR), to be decided by the Authority.
regulated by the width of that street and may
be continued to this height to a depth of
24 m along the narrower street subject to
conformity of 8; and
For buildings in vicinity of aerodromes,
provisions of 9.5 shall apply.
c)
9.4.2 Height Exceptions
9.4.2.1 Roof structures
The following appurtenant structures shall not be
included in the height of the building unless the
aggregate area of such structures, including pent-
houses, exceeds one-third of the area of the roof of
building upon which they are erected:
a) Roof tanks and their supports (with support
height not exceeding 1 m);
b) Ventilating, air-conditioning, lift rooms and
similar service equipment;
c) Stair cover (MUMTY) not exceeding 3 m in
height; and
d) Chimneys, parapet walls and architectural
features not exceeding 1.2 m in height.
9.4.2.2 The building height for different occupancy
types shall not exceed the maximum height prescribed
in Part 4 'Fire and Life Safety'.
9.5 Restrictions in the Vicinity of Aerodromes
9.5.1 For buildings in the vicinity of aerodromes, the
maximum height of such buildings shall be decided in
consultation with the Civil Aviation Authorities. This
shall be regulated by the rules for giving no objection
certificate for construction of buildings in the vicinity
of aerodromes of Directorate General of Civil Aviation,
which are given in Annex A. However, the latest rules
of Directorate General of Civil Aviation shall be
followed in all cases of buildings coming up in the
vicinity of an aerodrome.
9.5.1.1 For the purpose of 9.5.1 new buildings,
structures which rise to 30 m or more in height and are
to be located within 20 km of the aerodrome reference
point, shall be constructed only if no objection
certificate has been obtained from the Directorate
General of Civil Aviation.
9.5.1.2 In the case of buildings to be erected in the
vicinity of defence aerodromes, the maximum height
of such buildings shall be decided by the Defence
Authority.
9.5.2 This will apply specially to new constructions,
overhead high voltage/medium voltage lines,
telephones/telegraph lines, factories, chimneys, wire/
TV antennas.
9.5.2.1 No new chimneys or smoke producing
factories shall be constructed within a radius of 8 km
from the aerodrome reference point (ARP).
9.5.2.2 Overhead high voltage/medium voltage lines
or telephone/telegraph lines shall not be permitted in
the approach/take-off climb areas within 3 000 m of
the inner edge of these areas.
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
27
9.5.2.3 A 3 m margin shall be allowed in new
constructions for wireless/TV antennas, cooling towers
and MUMTIES.
9.5.3 Butcheries, tanneries and solid waste disposal
sites shall not be permitted within 10 km from the
aerodrome reference point.
9.6 Group Housing
9.6.1 Group housing development may be in low rise
house clusters or multi-storeyed apartments for high
density development.
9.6.2 No limit to floors and height shall be applicable,
but the coverage and floor area ratio for various
densities may be as given in Table 4 unless otherwise
provided in the Master Plan and local development
control rules.
Table 4 Floor Area Ratio and Coverage for
Group Housing
(Clause 9.6.2)
SI Net Residential
No. Density in Dwelling
Units/ Hectare
(1) (2)
Maximum
Coverage in
Percent
(3)
Floor Area
Ratio
(4)
i)
25
25
0.50
ii)
50
30
0.75
iii)
75
33
0.90
iv)
100
35
1.00
v)
125
35
1.25
vi)
150
35
1.50
vii)
175
35
1.75
NOTE
— The coverage
shall be calculated on the basis of the
whole <
area reserved for group housing.
9.6.3 The minimum size of the site for group housing
multi-storeyed apartment shall be 3 000 m 2 .
9.6.3.1 The number of dwelling units are calculated
on the basis of the density pattern given in the
Development Plan taking into consideration a
population of 4.5 persons per dwelling unit.
9.6.3.2 The basement may vary between 33.33
to 50 percent of the plot area and is to be used for
parking, servicing and for essential household storage
without counting in FAR.
9.6.3.3 One car parking space for every two flats up
to 90 m 2 floor area and one for every flat for 100 m 2 or
more shall be provided.
9.6.4 With a view to providing adequate parking for
occupancies and the vehicular load, appropriate off-
street parking provisions have to be made in the
building/on-site. This could also be permitted in
basement areas and the footprint for the basement
parking can exceed the ground coverage of the
building subject to no basement building construction
to cross the building line and all other safety features
for structural, fire, health and public safety being
ensured.
10 OFF-STREET PARKING SPACES
10.1 The off-street parking (on-site parking) spaces
in a plot to be provided shall be in accordance with
Annex B. The spaces given in Annex B shall be
considered by the Authority in conjunction with the
Development Rules, in force, if any.
10.2 The spaces to be left out for off-street parking as
given in 10.3 to 10.6 shall be in addition to the open
spaces left out for lighting and ventilation purposes as
given in 15.
10.2.1 Further 50 percent of the open spaces required
around buildings under 8 may be allowed to be utilized
for parking or loading or unloading spaces, provided a
minimum distance of 3.6 m around the building is kept
free from any parking, loading or unloading spaces
subject to the provisions of Part 4 Tire and Life Safety ' .
10.3 Each off-street parking space provided for
vehicles shall be as follows:
a) For car, the minimum parking space to be
3 m x 6 m when individual parking space is
required and 2.75 m x 5 m when common
parking space is required.
b) Space for scooter/two wheeler and bicycle
to be not less than 1.25 m 2 and 1.00 m 2
respectively.
c) Area for each equivalent car space inclusive
of circulation area is 23 m 2 for open parking,
28 m 2 for ground floor covered parking and
32 m 2 for basement.
10.4 For buildings of different occupancies, off-street
parking space for vehicles shall be provided as
stipulated below:
a) Motor Vehicles — Space shall be provided
as specified in Annex B for parking motor
vehicles (cars).
b) Other Types of Vehicles — For non-residential
building, in addition to the parking areas
provided in (a) above, 25 to 50 percent
additional parking space shall be provided for
parking other types of vehicles and the additional
spaces required for other vehicles shall be as
decided by the Authority, keeping in view the
nature of traffic generated in the city.
10.5 Off-street parking space shall be provided with
adequate vehicular access to a street; and the area of
drives, aisles and such other provisions required for
adequate manoeuvering of vehicle shall be exclusive
of the parking space stipulated in these provisions.
28
NATIONAL BUILDING CODE OF INDIA
10.6 If the total parking space required by these
provisions is provided by a group of property owners
for their mutual benefits, such use of this space may
be construed as meeting the off-street parking
requirements under these provisions, subject to the
approval of the Authority.
10.7 In buildings of mercantile (commercial),
industrial and storage type, in addition to the parking
spaces provided, a space at the rate of 3.5 m x 7.5 m,
shall be provided for loading and unloading activities,
for each 1 000 m 2 of floor area or fraction thereof.
10.8 Parking spaces shall be paved and clearly marked
for different types of vehicles.
10.9 Apart from parking at ground level, provision of
underground or multistoreyed parking may be
permitted. The parking of vehicles at different level
may also be mechanized. In the case of parking spaces
provided in basement(s), at least two ramps of adequate
width and slope shall be provided, located preferably
at opposite ends. In case of underground/multistoreyed
parking, special measures with regard to fire safety
shall be taken (see Part 4 Tire and Life Safety').
11 GREENBELTS, LANDSCAPING AND WATER
CONSERVATION
11.1 General
Greenbelts and landscaping including plantation of
shrubs and trees help to certain extent in enhancing
the environmental quality.
11.1.1 Planting of trees in streets and in open spaces
should be done carefully to take advantage of both
shades and sunshine without obstructing the flow of
wind circulation and sight. Their advantage for abating
glare and for providing cool and/or warm pockets in
developed areas should also be taken,
11.2 Norms for Planting of Shrubs and Trees
11.2.1 Suitable provisions may be made for greeneries
including plantation of shrubs and trees as a part of
environmental protection in general. This aspect shall
be taken care of from the initial stage of town and
country planning, zoning and planning of development
of particular area and group housing. Finally, this
aspect shall also be taken into account in planning
individual building of different occupancies.
11.2.2 The types of plants, the distance between trees/
plants from the building and the distance between plants
shall be carefully worked out keeping in view the
structural safety and aesthetic requirements of buildings.
11.3 Trees shall be numbered area-wise, plot-wise and
road-wise by the concerned authority and they shall
be checked periodically.
11.4 Cutting and pruning of trees in public as well as
private areas shall be suitably regulated. Trees shall
be cut only after obtaining the permission of the
Authority designated for this purpose.
11.5 The landscape planning and design shall be done
in accordance with Part 10 'Landscaping, Signs and
Outdoor Display Structures, Section 1 Landscape
Planning and Design'.
11.6 Water Conservation and Augmentation
In view of critical shortage of water, conservation of
water by rain water harvesting and by use of recycled
water to the maximum extent possible will be
required. In this regard the following provisions may
be adopted.
11.6.1 The local authority preparing a town-planning
scheme or a development plan should see that the local
water bodies are preserved, and if dry, are activated
by directing water-courses appropriately. If required,
the same should be enlarged, deepened, etc.
11.6.2 The water body should be protected by
ensuring that no permanent/temporary construction
development takes place around it up to a distance of
50 m from the edge of the water body and the same
shall be suitably landscaped. Further, the public shall
have easy access to the water body.
11.6.3 The rain water run-off shall be suitably directed
to Recharging Wells in plots belonging to the local
authority and of appropriate design.
11.6.4 The local authority should encourage for
collection of rain water from roofs and terraces and direct
the same either to a storage tank or to a recharging well.
11.6.5 Buildings having central air-conditioning plants
requiring water for cooling purposes may not be
allowed to use fresh water for the purpose.
11.6.6 Commercial or residential multi-storey complexes
may use recycled water for flushing of toilets. Separate
storage tanks and separate distribution pipes shall be
provided for the purpose.
12 REQUIREMENTS OF PARTS OR BUILDINGS
12.1 Plinth
12.1.1 Main Buildings
The plinth or any part of a building or outhouse shall
be so located with respect to the surrounding ground
level that adequate drainage of the site is assured. The
height of the plinth shall be not less than 450 mm from
the surrounding ground level.
12.1.2 Interior Courtyards and Covered Parking
Every interior courtyard shall be raised at least 150 mm
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
29
above the determining ground level and shall be
satisfactorily drained.
12.2 Habitable Rooms
12.2.1 Height
The height of all rooms for human habitation shall not
be less than 2.75 m measured from the surface of the
floor to the lowest point of the ceiling (bottom of slab).
In the case of pitched roof, the average height of rooms
shall not be less than 2.75 m. The minimum clear head
room under a beam, folded plates or eaves shall be
2.4 m. In the case of air-conditioned rooms, a height
of not less than 2.4 m measured from the surface of
the floor to the lowest point of air-conditioning duct
or the false ceiling shall be provided.
12.2.1.1 The requirements of 12.2.1 apply to
residential, business and mercantile buildings. For
educational and industrial buildings, the following
minimum requirements apply:
a) Educational Ceiling height 3.6 m for all
Buildings regions; in cold regions, 3 m
b)
Industrial
Buildings
Ceiling height 3.6 m, except
when air-conditioned, 3 m
(Factory Act 1948 and Rules
therein shall govern such
heights, where applicable).
12.2.2 Size
The area of habitable room shall not be less than 9.5 m 2 ,
where there is only one room with a minimum width
of 2.4 m. Where there are two rooms, one of these
shall not be less than 9.5 m 2 and the other not less than
7.5 m 2 , with a minimum width of 2.1 m.
12.3 Kitchen
12.3.1 Height
The height of a kitchen measured from the surface of
the floor to the lowest point in the ceiling (bottom slab)
shall not be less than 2.75 m, except for the portion to
accommodate floor trap of the upper floor.
12.3.2 Size
The area of a kitchen where separate dining area is
provided, shall be not less than 5.0 m 2 with a minimum
width of 1.8 m. Where there is a separate store, the
area of the kitchen may be reduced to 4.5 m 2 . A kitchen,
which is intended for use as a dining area also, shall
have a floor area of not less than 7.5 m 2 with a
minimum width of 2.1 m.
12.3.3 Other Requirements
Every room to be used as kitchen shall have:
a) unless separately provided in a pantry, means
for the washing of kitchen utensils which
shall lead directly or through a sink to a
grated and trapped connection to the waste
pipe;
b) an impermeable floor;
c) a flue, if found necessary; and
d) a window or ventilator or opening of size not
less than as specified in 15.1.1 subject to
increase in area of opening in accordance with
Note 3 of 15.1.2.
12.4 Bathrooms and Water-Closets
12.4.1 Height
The height of a bathroom or water-closet measured
from the surface of the floor to the lowest point in
the ceiling (bottom of slab) shall not be less than
2.1m.
12.4.2 Size
The area of a bathroom shall not be less than 1.8 m 2
with a minimum width of 1.2 m. The floor area of
water-closet shall be 1.1 m 2 with a minimum width of
0.9 m. If bath and water-closet are combined, its floor
area shall not be less than 2.8 m 2 with a minimum width
of 1.2 m.
12.4.3 Other Requirements
Every bathroom or water-closet shall:
a) be so situated that at least one of its walls shall
open to external air;
b) not be directly over or under any room other
than another water-closet, washing place, bath
or terrace, unless it has a water-tight floor;
c) have the platform or seat made of water-tight
non-absorbent material;
d) be enclosed by walls or partitions and the
surface of every such wall or partition shall
be finished with a smooth impervious material
to a height of not less than 1 m above the floor
of such a room;
e) be provided with an impervious floor
covering, sloping towards the drain with a
suitable grade and not towards VERANDAH
or any other room; and
f) have a window or ventilator, opening to a
shaft or open space, of area not less than
0.3 m 2 with side not less than 0.3 m.
12.4.4 No room containing water-closets shall be used
for any purpose except as a lavatory and no such room
shall open directly into any kitchen or cooking space
by a door, window or other opening. Every room
containing water-closet shall have a door completely
closing the entrance to it.
30
NATIONAL BUILDING CODE OF INDIA
12.5 Ledge or TAND/Loft
12.5.1 Height
The minimum head-room of ledge or TAND/loft shall
be 2.2 m. The maximum height of loft shall be 1.5 m.
12.5.2 Size
A ledge or TANDfloft in a habitable room shall not
cover more than 25 percent of the area of the floor on
which it is constructed and shall not interfere with the
ventilation of the room under any circumstances.
12.6 Mezzanine Floor
12.6.1 Height
It shall have a minimum height of 2.2 m.
12.6.2 Size
The minimum size of the mezzanine floor, if it is to be
used as a living room, shall not be less than 9.5 m 2 .
The aggregate area of such mezzanine floor in a
building shall in no case exceed one-third the plinth
area of the building.
12.6.3 Other Requirements
A mezzanine floor may be permitted over a room or a
compartment provided:
a) it conform to the standard of living rooms as
regards lighting and ventilation in case the
size of mezzanine floor is 9.5 m 2 or more
(see 14.1.2);
b) 'it is so constructed as not to interfere under
any circumstances with the ventilation of the
space over and under it;
c) such mezzanine floor is not sub-divided into
smaller compartments;
d) such mezzanine floor or any part of it shall
not be used as a kitchen; and
e) in no case shall a mezzanine floor be closed
so as to make it liable to be converted into
unventilated compartments.
12.7 Store Room
12.7.1 Height
The height of a store room shall be not less than 2.2 m.
12.7.2 Size
The size of a store room, where provided in a residential
building, shall be not less than 3 m 2 .
12.8 Garage
12.8.1 Height
The height of a garage shall be not less than 2.4 m.
12.8.2 Size
The size of garages shall be as below:
a) Private Garage — 3.0 m x 6.0 m, minimum;
and
b) Public Garage — Based on the number of
vehicles parked, etc (see 10).
12.9 Basement
12.9.1 The basement shall not be used for residential
purposes.
12.9.2 The construction of the basement shall be
allowed by the Authority in accordance with the
land use and other provisions specified under the
Development Control Rules.
12.9.2.1 The basement to be constructed within the
building envelope and subject to maximum coverage
on floor 1 (entrance floor) may be put to only the
following uses:
a) Storage of household or other goods of
ordinarily non-combustible material;
b) Strong rooms, bank cellars, etc;
c) Air-conditioning equipment and other
machines used for services and utilities of the
building; and
d) Parking spaces.
12.9.3 The basement shall have the following
requirements:
a) Every basement shall be in every part at least
2.4 m in height from the floor to the underside
of the roof slab or ceiling;
b) Adequate ventilation shall be provided for the
basement. The ventilation requirements shall
be the same as required by the particular
occupancy according to byelaws. Any
deficiency may be met by providing adequate
mechanical ventilation in the form of blowers,
exhaust fans, air-conditioning systems, etc;
c) The minimum height of the ceiling of any
basement shall be X).9 m and the maximum,
1.2 m above the average surrounding ground
level;
d) Adequate arrangements shall be made such
that surface drainage does not enter the
basement;
e) The walls and floors of the basement shall be
watertight and be so designed that the effects
of the surrounding soil and moisture, if any,
are taken into account in design and adequate
damp proofing treatment is given; and
f) The access to the basement shall be separate
from the main and alternative staircase
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
31
providing access and exit from higher floors.
Where the staircase is continuous in the case
of buildings served by more than one
staircase, the same shall be of enclosed type
serving as a fire separation from the basement
floor and higher floors. Open ramps shall be
permitted if they are constructed within the
building line subject to the provision of (d).
The exist requirements in basements shall comply with
the provisions of Part 4 Tire and Life Safety'.
12.10 Chimneys
The chimneys shall be built at least 0.9 m above flat
roofs, provided the top of the chimneys is not below
the top of the adjacent parapet wall. In the case of
sloping roofs, the chimney top shall not be less than
0.6 m above the ridge of the roof in which the chimney
penetrates.
12.11 Parapet
Parapet walls and handrails provided on the edges of
roof terraces, balcony, VARANDAH, etc shall not be
less than 1 .0 m and not more than 1 .2 m in height from
the finished floor level.
12.12 Cabin
The size of cabins shall not be less than 3.0 m 2 with a
minimum width of 1 .0 m. The clear passages within
the divided space of any floor shall not be less than
0.75 m and the distance from the farthest space in a
cabin to any exit shall not be more than 18.5 m. In
case the sub-divided cabin does not derive direct
lighting and ventilation from any open spaces/
mechanical means, the maximum height of the cabin
shall be 2.2 m.
12.13 Boundary Wall
12.13.1 The requirements of the boundary wall are
given below:
a) Except with the special permission of the
Authority, the maximum height of the
compound wall shall be 1.5 m above the
centre line of the front street. Compound wall
up to 2.4 m height may be permitted if the
top 0.9 m is of open type construction of a
design to be approved by the Authority.
b) In the case of a corner plot, the height of the
boundary wall shall be restricted to 0.75 m
for a length of 10 m on the front and side of
the inter-sections and the balance height of
0.75 m if required in accordance with (a) may
be made up of open type construction
(through railings) and of design to be
approved by the Authority.
c) However, the provisions of (a) and (b) are not
applicable to boundary walls of jails. In
industrial buildings, electric sub-stations,
transformer stations, institutional buildings
like sanitoria, hospitals, industrial buildings
like workshops, factories and educational
buildings like schools, colleges, including
hostels, and other uses of public utility
undertakings and strategically sensitive
buildings, a height up to 2.4 m may be
permitted by the Authority.
12.14 Wells
Wells, intended to supply water for human consumption
or domestic purposes, where provided, shall comply with
the requirements of 12.14.1 and 12.14.2.
12.14.1 Location
The well shall be located:
a) not less than 15 m from any ash pit, refuse
pit, earth closet or privy and shall be located
on a site upwards from the earth closet or
privy;
b) not less than 18 m from any cess pit soakway
or borehole latrine and shall be located on a
site upwards from the earth closet or privy;
c) that contamination by the movement of sub-
soil or other water is unlikely; and
d) not under a tree or otherwise it should have a
canopy over it, so that leaves and twigs may
not fall into the well and rot.
12.14.2 Requirements
The well shall:
a) have a minimum internal diameter of not less
than 1 m;
b) be constructed to a height not less than 1 m
above the surrounding ground level, to form a
parapet or kerb and to prevent surface water
from flowing into a well, and shall be
surrounded with a paving constructed of
impervious material which shall extend for a
distance of not less than 1 .8 m in every direction
from the parapetfrom the kerb forming the well
head and the upper surface of such a paving
shall be sloped away from the well;
c) be of sound and permanent construction
(PUCCA) throughout. Temporary or exposed
(KUTCHA) wells shall be permitted only in
fields or gardens for purposes of irrigation; and
d) have the interior surface of the lining or walls
of the well be rendered impervious for a
depth of not less than 1.8 m measured
from the level of the ground immediately
adjoining the well-head.
32
NATIONAL BUILDING CODE OF INDIA
12.15 Septic Tanks
Where a septic tank is used for sewage disposal, the
location, design and construction of the septic tank shall
conform to requirements of 12.15.1 and 12.15.2 [see
also Part 9 'Plumbing Services, Section 1 Water
Supply, Drainage and Sanitation (Including Solid
Waste Management)'].
12.15.1 Location of the Septic Tanks and Subsurface
Absorption Systems
A sub-soil dispersion system shall not be closer than
18 m from any source of drinking water, such as well,
to mitigate the possibility of bacterial pollution of water
supply. It shall also be as far removed from the nearest
habitable building as economically feasible but not
closer than 6 m, to avoid damage to the structures.
12.15.2 Requirements
a) Dimensions of septic tanks — Septic tanks
shall have a minimum width of 750 mm, a
minimum depth of 1 m below the water level
and a minimum liquid capacity of 1 m 3 . The
length of tanks shall be 2 to 4 times the width;
b) Septic tanks may be constructed of brickwork,
stone masonry, concrete or other suitable
materials as approved by the Authority;
c) Under no circumstances shall effluent from a
septic tank be allowed into an open channel
drain or body of water without adequate
treatment;
d) The minimum nominal diameter of the pipe
shall be 100 mm. Further, at junctions of pipes
in manholes, direction of flow from a branch
connection shall not make an angle exceeding
45° with the direction of flow in the main pipe;
e) The gradients of land drains, under-drainage
as well as the bottom of dispersion trenches
and soakways shall be between 1:300 and
1:400;
f) Every septic tank shall be provided with
ventilating pipe of at least 50 mm diameter.
The top of the pipe shall be provided with a
suitable cage of mosquito-proof wire mesh.
The ventilating pipe shall extend to a height
which would cause no smell nuisance to any
building in the area. Generally, the ventilating
pipe may extend to a height of about 2 m,
when the septic tank is at least 15 m away
from the nearest building and to a height of
2 m above the top of the building when it is
located closer than 15 m;
g) When the disposal of septic tank effluent is
to a seepage pit, the seepage pit may be of
any suitable shape with the least cross-
sectional dimension of 0.90 m and not less
than 1 .00 m in depth below the invert level of
the inlet pipe. The pit may be lined with stone,
brick or concrete blocks with dry open joints
which should be backed with at least 15 mm
of clean coarse aggregate. The lining above
the inlet level should be finished with mortar.
In the case of pits of large dimensions, the
top portion may be narrowed to reduce the
size of the RCC cover slabs. Where no lining
is used, specially near trees, the entire pit
should be filled with loose stones. A masonry
ring may be constructed at the top of the pit
to prevent damage by flooding of the pit by
surface runoff. The inlet pipe may be taken
down a depth of 0.90 m from the top as an
anti-mosquito measure; and
h) When the disposal of the septic tank effluent
is to a dispersion trench, the dispersion trench
shall be 0.50 m to 1.00 m deep and 0.30 m to
1.00 m wide excavated to a slight gradient
and shall be provided with 150 mm to 250 mm
of washed gravel or crushed stones. Open
jointed pipes placed inside the trench shall
be made of unglazed earthenware clay or
concrete and shall have a minimum internal
diameter of 75 mm to 100 mm. Each
dispersion trench shall not be longer than
30 m and trenches shall not be placed closer
than 1.8 m.
12.16 Office-cum-Letter Box Room
In the case of multi-storeyed multi-family dwelling
apartments constructed by existing and proposed
Cooperative Housing Societies or Apartment Owners
Associations, limited companies and proposed
societies, an office-cum-letter box room of dimension
3.6 m x 3 m shall be provided on the ground floor. In
case the number of flats is more than 20, the maximum
size of the office-cum-letter box room shall be 20 m 2 .
12.16.1 Business Buildings
Provision shall be made for letter boxes on the entrance
floor as per the requirements of the postal department.
12.17 Meter Rooms
For all buildings above 15 m in height and in special
occupancies, like educational, assembly, institutional,
industrial, storage, hazardous and mixed occupancies
with any of the aforesaid occupancies having area more
than 500 m 2 on each floor, provision shall be made for
an independent and ventilated meter (service) room,
as per requirements of electric (service) supply
undertakings on the ground floor with direct access
from outside for the purpose of termination of electric
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
33
supply from the licensee's service and alternative
supply cables. The door/doors provided for the service
room shall have fire resistance of not less than two
hours.
12.18 Staircase/Exit Requirements
12.18.1 The minimum clear width, minimum tread
width and maximum riser of staircases for buildings
shall be as given in 12.18.1.1 to 12.18.1.3 {see also
Part 4 'Fire and Life Safety').
12.18.1.1 Minimum width — The minimum width of
staircase shall be as follows:
a) Residential buildings (dwellings) 1.0 m
NOTE — For row housing with 2 storeys,
the minimum width shall be 0.75 m.
b)
Residential hotel buildings
1.5 m
c)
Assembly buildings like
auditoria, theatres and cinemas
2.0 m
d)
Educational building
1.5 m
e)
Institutional buildings
2.0 m
f)
All other buildings
1.5 m
12.18.1.2 Minimum tread
The minimum width of tread without nosing shall be
250 mm for residential buildings. The minimum width
of tread for other buildings shall be 300 mm.
12.18.1.3 Maximum riser
The maximum height of riser shall be 190 mm for
residential buildings and 150 mm for other buildings
and these shall be limited to 12 per flight.
12.18.2 The minimum head-room in a passage under
the landing of a staircase shall be 2.2 m. The minimum
clear head-room in any staircase shall be 2.2 m.
12.18.3 Exit Requirements
All aspects of exit requirements for corridors, doors,
stair cases, ramps, etc in respect of widths, travel
distance shall be as per Part 4 Tire and Life Safety'.
12.19 Roofs
12.19.1 The roof of a building shall be so designed
and constructed as to effectively drain water by means
of sufficient rain-water pipes of adequate size,
wherever required, so arranged, jointed and fixed as
to ensure that the rain-water is carried away from the
building without causing dampness in any part of the
walls, roof or foundations of the building or an adjacent
building.
12.19.2 The Authority may require rain-water pipes
to be connected to a drain or sewer to a covered channel
formed beneath the public footpath to connect the rain-
water pipe to the road gutter or in any other approved
manner.
12.19.3 Rain-water pipes shall be affixed to the
outside of the external walls of the building or in
recesses or chases cut or formed in such external walls
or in such other manner as may be approved by the
Authority.
12.19.4 It is desirable to conserve rain water using
suitable rain water harvesting techniques including by
roof water collection. In this context, reference may
be made to Part 9 'Plumbing Services, Section 1 Water
Supply, Drainage and Sanitation (Including Solid
Waste Management)'.
12.20 Special Requirements of Low Income
Housing
Special requirements of low income housing shall be
as given in Annex C. For detailed information in this
regard, reference may be made to the accepted
standards [3(1)].
12.21 Special Requirements for Physically Challenged
Special requirements for planning of buildings and
facilities keeping in view the needs of the physically
challenged, applicable particularly to public buildings
meant for their use, are given in Annex D.
12.22 Special Requirements for Cluster Planning
for Housing
Special requirements for cluster planning for housing
shall be as given in Annex E.
12.23 Special Requirements for Low Income
Habitat Planning in Rural Areas
Special requirements for low income habitat planning
in rural areas shall be as given in Annex F.
12.24 Special Requirements for Development
Planning in Hilly Areas
Special requirements for development planning in hilly
areas is given in Annex G.
13 FIRE AND LIFE SAFETY
For requirements regarding fire and life safety for
different occupancies, reference shall be made to Part 4
Tire and Life Safety'.
14 DESIGN AND CONSTRUCTION
For requirements regarding structural design, reference
shall be made to Part 6 * Structural Design' and for
construction (including safety) reference shall be made
to Part 7 'Constructional Practices and Safety'.
15 LIGHTING AND VENTILATION
15.1 For requirements regarding lighting and
34
NATIONAL BUILDING CODE OF INDIA
ventilation for different uses and occupancies,
reference shall be made to Part 8 'Building Services,
Section 1 Lighting and Ventilation'.
15.1.1 Lighting and Ventilation of Rooms
Rooms shall have, for the admission of light and air,
one or more openings, such as windows and ventilators,
opening directly to the external air or into an open
VERANDAH.
15.1.2 Notwithstanding the area of openings obtained
through 15.1, the minimum aggregate area (see Notes
1 to 3) of such openings, excluding doors inclusive of
frames, shall be not less than:
a) one-tenth of the floor area for dry hot climate;
b) one-sixth of the floor area for wet hot
climate;
c) one-eighth of the floor area for intermediate
climate; and
d) one-twelfth of the floor area for cold climate,
NOTES
1 If a window is partly fixed, the openable area shall
be counted.
2 No portion of a room shall be assumed to be lighted,
if it is more than 7.5 m away from the opening assumed
for lighting that portion.
3 The area of openings as given in (a) to (d) above
shall be increased by 25 percent in the case of a kitchen
[see 12.3.3(d)].
16 ELECTRICAL AND ALLIED INSTALLATIONS
(INCLUDING LIGHTNING PROTECTION OF
BUILDINGS)
For requirements regarding electrical installations in
buildings including lightning protection of buildings,
reference shall be made to Part 8 'Building Services,
Section 2 Electrical and Allied Installations'.
17 AIR CONDITIONING, HEATING AND
MECHANICAL VENTILATION
For requirements regarding design, construction and
installation of air conditioning, heating and mechanical
ventilation systems, reference shall be made to Part 8
'Building Services, Section 3 Air Conditioning,
Heating and Mechanical Ventilation'.
18 ACOUSTICS, SOUND INSULATION AND
NOISE CONTROL
For requirements regarding the desired noise levels and
sound insulation in different occupancies, reference
shall be made to Part 8 'Building Services, Section 4
Acoustics, Sound Insulation and Noise Control' .
19 HEAT INSULATION
For calculation of solar radiation on buildings and
recommended limits of thermal transmittance of roofs
and walls for different parts of the country and heat
transmission losses due to different constructions,
reference may be made to good practice [3(2)].
20 INSTALLATION
ESCALATORS
OF LIFTS AND
Provision for lifts shall be made for buildings 15 m or
more in height. For requirements regarding planning,
designing and installation, etc of lifts and escalators,
reference shall be made to Part 8 'Building Services,
Section 5 Installation of Lifts and Escalators'.
21 PLUMBING SERVICES AND SOLID WASTE
MANAGEMENT
For requirements regarding water supply, drainage and
sanitation (including solid waste management) and gas
supply, reference shall be made to Part 9 'Plumbing
Services'.
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
35
ANNEX A
(Clause 9.5.1)
CIVIL AVIATION REQUIREMENTS FOR CONSTRUCTION IN THE
VICINITY OF AN AERODROME
A-0 GENERAL
A-0.1 For the purpose of this Annex, the following
definitions shall apply.
A -0.1.1 Aerodrome Reference Point (ARP) — This is
a designated point, which is established in the
horizontal plane at or near the geometric centre of the
landing area.
A-0.1.2 Approach Funnel — See Fig. 8.
A-0. 1.3 Elevation or Reduced Level — The vertical
distance of a point or a level, on or affixed to the surface
of the earth, measured from the mean sea level.
A-0.1.4 Transitional Area — An area which is below
a specified surface sloping upwards and outwards from
the edge of the approach funnel and from a line
originating at the end of the inner edge of each
approach area, drawn parallel to the runway centre line
in the direction of landing (see Fig. 8).
A-0.1.5 Runway Strip — See Fig. 8.
A-l PROHIBITED AREA
A-l.l No building or structure shall be constructed
or erected, or no tree shall be planted, on any land
within the limits specified in A-1.2 and A-1.3 in respect
of the aerodromes listed in A-3 and in respect of the
aerodrome at Thiruvananthapuram.
A-1.2 For the Aerodromes (see A-3)
These requirements shall be applicable for the land
enclosed in approach funnels of the runway with a
maximum distance of 360 m measured from each
runway and along the extended centre line of the
runway. For the purpose of this clause, the requirements
of approach funnel and an instrument runway shall be
as given in A-l.2.1 to A-l.2.3.
A-l.2.1 Approach funnel in the case of an instrument
runway means the area in the shape of an isosceles
trapezium having the longer parallel side 4 800 m long
(2 400 m on either side of the extended centre line of
the runway) and smaller parallel side 300 m long
(150 m on either side of the extended centre line of
the runway) where the smaller and longer parallel sides
are placed at a distance of 60 m and 15 060 m,
respectively, from the end of the runway and at right
angles to the extended centre line.
A-l.2.2 In the case of a non-instrument runway, the
approach funnel means the area in the shape of an
isosceles trapezium having the longer parallel side
1 800 m long (900 m on either side of the extended
centre line of the runway) and smaller parallel side
180 m long (90 m on either side of the extended centre
line of the runway), where the smaller and longer
parallel sides are placed at a distance of 60 m and
6 540 m, respectively, from the end of the runway and
at right angles to the extended centre line. Thereafter,
the trapezium is followed by a contiguous rectangular
area of that width for the remainder of the length up to
a distance of 15 060 m from the end of the runway.
A-l.2.3 An instrument runway is a runway served by
visual and non-visual aid or aids providing at least
directional guidance adequate for a straight in approach
and intended for the operation of aircraft using
instrument approach procedures.
A-1.3 For the Aerodrome at Thiruvananthapuram
These requirements shall be applicable for the land
enclosed in approach funnels of all runways with a
maximum distance of 304.80 m, measured from each
runway and along extended centre line of the runway,
and the land enclosed in a belt of 30.48 m width outside
the operational boundary of the aerodrome. For the
purpose of this clause, the requirements of approach
funnel and operational boundary shall be as given
in A-l.3,1 and A-l.3.2.
A-l.3.1 Approach funnel means the area in the shape
of an isosceles trapezium having the longer parallel side
of length 4 724.4 m (2 362.2 m on either side of the
extended centre line of the runway) and smaller parallel
side of 152.4 m (76.2 m on either side of the extended
centre line of the runway) where the smaller and longer
parallel sides are placed at a distance of 60.9 m and
15 301 m, respectively, from the end of the runway and
at right angles to the extended centre line.
A-l.3.2 Operational boundary means an area enclosed
between parallel lines at a distance of 152.4 m on either
side of the centre line of the runways or 30.4 m from
the boundary fencing of the aerodrome, whichever is
greater.
A-2 HEIGHT RESTRICTION
A-2.1 For the Aerodromes (see A-3)
No building or structure higher than the height
specified in Tables 5 and 6 shall be constructed or
36
NATIONAL BUILDING CODE OF INDIA
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8A INSTRUMENT RUNWAY
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J NON-INSTRUMENT RUNWAY
All dimensions in metres.
Fig. 8 Runway
erected, or no tree which is likely to grow or ordinarily
grows higher than the height specified in the Tables 5
and 6, shall be planted, on any land within a radius of
20 km from ARP of the aerodromes listed in A-3,
excluding the land covered by A-1.2.
Table 5 Height Restriction with Respect to
Approach Funnels
(Clauses A-2.1 and A-2.1.1)
SI
No.
(1)
Area
(2)
Maximum Permissible
Height Above the
Elevation of the Nearest
Runway End
(3)
i) More than 360 m but not
exceeding 510 m
ii) More than 510 m but not
exceeding 660 m
iii) More than 660 m but not
exceeding 810 m
iv) More than 810 m but not
exceeding 960 m
v) More than 960 m but not
exceeding 1 1 10 m
vi) More than 1 110 m but not
exceeding 1 260 m
vii) More than 1 260 m but not
exceeding 1 410 m
viii) More than 1 410 m but not
exceeding 1 560 m
ix) More than 1 560 m
6
9
12
15
18
.21
24
27
30
A-2.1.1 Table 5 gives the height restriction with
respect to approach funnels and shall be applicable for
the land enclosed in the approach funnels of all runways
where distances are measured from each end of the
runway, along extended centre line of the runway.
A-2.1.2 Table 6 gives height restriction with respect
to transitional area and shall be applicable for the land
enclosed in the transitional area of all runways at an
aerodrome listed in A-3 where distances are measured
from the associated runway strip and the edge of the
associated approach funnels, forming the inner
boundary of the transitional area and along a line at
right angles to the centre line of the runway.
A-2.2 For the Aerodrome at Thiruvananthapuram
No building or structure higher than the height
specified in Table 7 shall be constructed or erected, or
no tree which is likely to grow or ordinarily grows
higher than the height specified in Table 7, shall be
planted, on any level within a radius of 20 km from
ARP of the aerodrome at Thiruvananthapuram,
excluding the land covered by A-1.3.
Table 6 Height Restriction with Respect to
Transitional Area
(Clauses A-2.1 and A-2.1.2)
SI
Distance from the Inner
Maximum Permissible
No.
Boundary of the Transitional
Height Above the
Area Specified Above
Elevation of the ARP
(1)
(2)
(3)
i) Up to a distance of 21 m
ii) More than 21 m but not
exceeding 42 m
iii) More than 42 m but not
exceeding 63 m
iv) More than 63 m but not
exceeding 84 m
v) More than 84 m but not
exceeding 105 m
vi) More than 105 m but not
exceeding 126 m
vii) More than 1 26 m but not
exceeding 147 m
viii) More than 147 m but not
exceeding 168 m
ix) More than 168 m but not
exceeding 189 m
x) More than 189 m but not
exceeding 210m
xi) Morethan210m
3
6
9
12
15
18
21
24
27
30
Table 7 Height Restriction
(Clause A-2.2)
SI
No.
(1)
Area
(2)
Maximum
Permissible Height
Above Ground
Level
(3)
i) The area lying between the coastline 3
and the Chakai canal other than
specified in A-13
ii) The area lying in a belt of 457.2 m 6
width between the Eastern Bank of
the Chakai canal and a line running
parallel to this canal for the entire
length
iii) A parallel belt of 762 m width 15.2
running East of area (ii) above
iv) A parallel belt of 609.6 m width 24.3
running East of area (iii) above
v) Rest of the area extending up to 20 30.4
km from ARP
A-3 AERODROMES
A-3.1 A list of aerodromes indicating runway
directions, runway elevations and ARP elevations is
given in Table 8.
38
NATIONAL BUILDING CODE OF INDIA
Table 8 Runway Directions, Runway End
Table 8
— Continued
Elevations and ARP Elevations for Aerodromes
(1)
(2)
(3)
(4)
(5)
(Clause A-3.1)
17.
Chennai
10.5
07
25
12
SI Aerodrome
ARP
Runway
Runway End
15.5
No.
Elevation
m
No.
Elevation
12
30
9
13
(1) (2)
(3)
(4)
(5)
18.
Coimbatore
396
05
23
402
391
1. Ahmadabad
55
14
32
54
56
19.
Cooch-Behar
41.5
04
22
41.5
41.5
05
54
20.
Delhi (Palam)
227
10
219
23
56
28
236.5
2. Agartala
14
05
23
12
14.5
09
27
220
229
18
13.5
21.
Delhi (Safdarjung)
212
12
215
36
13.5
30
212
3. Akola
305
10
28
303
303
22.
Dibrugarh
109.5
05
23
109
109.5
4. Amritsar
229
07
25
229
230
23.
Gauhati
48
03
21
49
48
16
230
24.
Gaya
110
10
108
34
229
28
115.5
5. Aurangabad
581
09
27
582
573.5
01
19
109
111
6. Belgaum
758
08
26
755
747
25.
Hyderabad
531
09
27
530
522
7. Balurghat
24
09
27
24
23
14
32
531
528
8. Bangalore
888
09R
27L
875
881
26.
Indore
561
07
25
563.5
559.5
09L
876
27.
Jabalpur
495
06
480
27R
882.5
24
494.5
9. Vadodara
37
04
22
09
27
36.5
37.5
36.5
38.7
28.
Jaipur
385
15
33
09
27
389.5
384.4
383.7
381.3
10. Behala
2.6
18
36
3.5
3.5
29.
Jhansi
236
15
33
236.5
236.5
1 1 . Bhavnagar
5.4
07
25
11
6
30.
Jharsuguda
228
06
24
228.20
229.14
12. Bhopal
523
06
24
522.5
521
31.
Kailashadar
27.5
03
21
28.5
27.5
12
521.5
32.
Kamalpur
39
01
45
30
523
19
41
13. Bhubaneshwar
44.5
05
23
33
41.5
33.
Kandla
29
05
23
29
29
14
38
34.
Kanpur
m
10
125
32
37
28
124.5
14. Bhuj
78.5
05
23
11
29
81.5
74.5
79
77.5
35.
Keshod
49.5
05
23
18
36
50.5
50.5
50
52
15. Bilaspur
274
06
24
270
282
36.
Khajuraho
217.4
01
19
222
210
17
276
37.
Kolhapur
607
07
609.6
35
269
25
605.6
16. Chakulia
129
08
26
17
38
135
132
130
27
38.
Kolkata
5.3
OIL
19R
01R
19L
4.8
5
5
4.5
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
39
Table 8 — Continued
Table 8 — Concluded
(1) (2)
(3)
(4)
(5)
(1) (2)
(3)
(4)
(5)
39. Kota
273
08
272
57. Pantnagar
233
10
234
26
272
28
234
40. Kulu
1084
16
1089
58. Porbandar
5
09
6.7
34
1088
27
4.5
41. Khowai
29
18
26
59. Port Blair
6
04
3.66
36
27
22
17.8
42. Lalitpur
367
10
368.5
60. Raipur
313.6
06
309
28
363
24
316
43. Lilabari
100.2
04
101.5
61. Rajahmundry
45
05
34
22
101.5
23
46
44. Lucknow
122
09
122
62. Rajkot
134
05
133
27
122
23
128.5
01
122
14
130
19
123
32
133.5
45. Madurai
136.30
09
140
63. Ranchi
646
13
654
27
130
31
632.5
13
138.5
64. Satna
319
11
316.5
31
136
29
316
46. Malda
24
11
24
65. Sholapur
418
15
478.5
29
23.5
33
478
47. Mangalore
102
09
97
66. Silchar
102
06
98.5
27
89
24
107.5
48. Mumbai (Juhu)
3
08
5
67. Tanjore
76
14
77
26
2.5
32
70.5
04
2.5
07
76.5
22
2.5
25
74.5
16
2.5
68. Tiruchchirappalli
85
15
84
34
2.5
33
85
49. Mumbai (Santacruz)
8
09
4
09
88
27
10
27
84
14
11
69. Tirupati
103
08
106.4
32
7.5
26
102
50. Muzaffarpur
53
11
53
70. Tulihal (Imphal)
774.5
04
773.5
29
53
22
775
5 1 . Mysore
715.5
05
720
71. Udaipur
509
08
511.5
23
710
26
508
09
717.5
72. Varanasi
80
09
80
27
708
27
80
52. Nagpur
308.5
09
309
73. Vijayawada
21
08
25
27
301
26
21.5
14
315
74. Vishakhapatnam
3
05
4
32
307
23
2
53. Panagarh
73
15
71
09
4
33
73
27
2
54. Panna
425
17
435.80
18
4
35
410.35
36
4
55. Passighat
155.5
17
156.5
75. Warangal
285
15
290
35
153
33
276.5
56. Patna
51
07
52
09
289
25
52
27
280.5
40
NATIONAL BUILDING CODE OF INDIA
ANNEX B
(Clause 10.1)
OFF-STREET PARKING SPACES
The off-street parking spaces shall be as given below:
SI
Occupancy
One Car Parking Space
for Every
No.
Population
less than
50 000
Population
50 000 to
200 000
Population
Between
200 000 to
1 000 000
Population
Between
1000 000 to
5 000 000
Population
Above
5 000 000
(1)
(2)
(3)
(4)
(5)
(6)
(7)
i)
Residential
a) Multi-family
—
—
a) 2 tenements
having built-
up area 101
to 200 m 2
b) 1 tenement of
200 m 2 built-
up area
1 tenement of
100 m 2 built-
up area
1 tenement of
75 m 2 built-up
area
b) Lodging
establishments,
tourist homes and
hotels, with lodging
accommodation
12 guest
rooms
8 guest
rooms
4 guest
rooms
3 guest
rooms
2 guest
rooms
ii)
Educational
(see Note 1)
—
—
2
70 m area or
fraction
50 m area or
fraction
35 m area or
fraction
iii) Institutional (Medical)
iv) a) Assembly halls,
cinema theatres
b) Restaurants
c) Marriage halls,
community halls
d) Stadia and
exhibition centre
v) a) Business offices
and firms for
private business
b) Public or semi-
public offices
20 beds
(Private)
30 beds
(Public)
120 seats
60 seats
thereof of the
administrative
office area and
public service
areas
15 beds 10 beds (Private)
(Private)
25 beds 15 beds (Public)
(Public)
80 seats 25 seats
40 seats
600 m 2 plot 400 m 2 plot
area
240 seats
2
300 m area
or fraction
thereof
500 m area
or fraction
thereof
area
160 seats
2
200 m area
or fraction
thereof
2
300 m area
or fraction
thereof
20 seats
200 m 2 plot
area
50 seats
2
100 m area
or fraction
thereof
200 m area
or fraction
thereof
thereof of the
administrative
office area and
public service
areas
5 beds
(Private)
10 beds
(Public)
15 seats
10 seats
50 m plot
area
30 seats
50 m area
or fraction
thereof
100 m area
or fraction
thereof
thereof of the
administrative
office area and
public service
areas
2 beds
(Private)
5 beds
(Public)
10 seats
5 seats
25 m 2 plot
area
20 seats
2
25 m area
or fraction
thereof
50 m area
or fraction
thereof
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
41
(1)
(2)
(3)
(4)
(5)
(6)
(7)
vi) Mercantile
(see Note 2)
vii) Industrial
viii) Storage
300 m area
or fraction
thereof
400 m 2 area
or fraction
thereof
200 m area
or fraction
thereof
300 m 2 area
or fraction
thereof
100 m area
or fraction
thereof
200 m 2 area
or fraction
thereof
500 m 2 floor
area or part
thereof
50 m area
or fraction
thereof
100 m 2 area
or fraction
thereof
250 m 2 area
or fraction
thereof
25 m area
or fraction
thereof
50 m 2 area
or fraction
thereof
125 m 2 area
or fraction
thereof
NOTES
1 In the case of auditoria for educational buildings, parking space shall be provided as per SI No. (iv)
2 For plots up to 50 m 2 , as in the case of shops, parking spaces need not be insisted upon.
3 For other institutions, transport/communication centre, parking space requirement shall be assessed based on the proposed building.
ANNEX C
(Clause 12.20)
SPECIAL REQUIREMENTS FOR LOW INCOME HOUSING IN URBAN AREAS
C-l GENERAL
C-l.l These guidelines cover the planning and
general building requirements of low income housing
for houses having a maximum plinth area of 40 m 2
including future expansion. The requirement
regarding layout planning of low income housing
colonies are applicable to public and private agencies/
government bodies. The requirements on design and
construction of buildings for low income housing in
approved layouts are applicable to all private and
public agencies.
C-1.2 In these planning standards, the general master
plan requirement for community open spaces estimated
at 0.3 ha for thousand persons is provided; road areas
are worked out between 10 and 20 percent of the site
area; one nursery school of 0.1 ha is provided for a
population of 1 500 and shopping centres at 4 shops
per thousand population are also covered.
C-1.3 It is emphasized that this type of development
should apply to clusters of 400 dwelling units, so
distributed in the development under consideration as
to maintain the overall densities of the master plan for
the area.
C-2 PLANNING
C-2.1 Type of Development
The type of development for low income housing shall
be plotted developments as row housing/flatted
development as row housing or group housing on
cluster pattern.
C-2.2 Layout Pattern
C-2.2.1 In the land to be developed, at least 75 percent
of the plots may be of the size less than or up to 60 m 2
per dwelling unit in metropolitan towns and 100 m 2 in
other towns and hill areas. Remaining 25 percent of
the plots may be more than 60 m 2 , however, no plot
shall be more than 200 m 2 . In case of group housing or
flatted development at least 75 percent units should
have a plinth area (excluding external circulation such
as stairs, lifts, lobbies, etc) up to or not exceeding 40 m 2
including future expansion.
C-2.2.2 The mix of plot of different sizes should have
a wide range to accommodate the need of lower income
group. The project may include more than one site
provided they are in the same neighbourhood.
C-2.2.3 The layout should generally conform to the
following land use:
Land Under Each Use
Saleable
i) Residential
General Hill Area
50 percent, 35 percent
Min
ii) Work places, schools, 20 percent, 15 percent
institutions, shops, Max
community places, etc
Non-Saleable
Roads, pedestrian paths, 30 percent, 50 percent
drains, public and semi- Max
public open spaces
NOTES
1 Any neighbourhood development should have provision for
42
NATIONAL BUILDING CODE OF INDIA
basic civic and community facilities, however, where such
facilities are available in proximity the same could be considered
and, in that case, the area under residential use could be increased
correspondingly.
2 If land required under statutory provisions of master plan/
development plan is proportionately higher but serves larger
city needs, re-adjustment of the recommended land use pattern
can be considered. Such provisions should, however, be
carefully reviewed by the planning authorities to keep them to
the barest minimum levels.
C-2.3 Plot Area
C-2.3.1 Plot Size
The minimum plot size with ground coverage not
exceeding 75 percent, shall not be less than 40 m 2 in
small and medium town and not less than 30 m 2 in
metropolitan cities. Plot sizes below 30 m 2 but not less
than 15 m 2 may be permitted in case of cluster planning ,
however, in such cases the ground coverage and FSI
shall be 100 percent and 2 percent respectively (see
also Annex E for Special requirements for cluster
planning for housing).
NOTES
1 In exceptional cases in metropolitan cities with population
more than 1 million the size of plots may be brought down to
25 m 2 in cases of low income housing colonies located in
congested areas as decided by the Authority. In mega-cities it
may be further reduced to 15 m 2 . In such cases where plot size
is below 25 m 2 , only cluster planning or group housing may
be adopted.
2 A minimum of 25 percent of the plot size shall be left open
without adversely affecting light and ventilation for habitable
spaces and toilet. It shall not be made mandatory to leave set
back on any side.
C-2.3.2 Minimum Frontage
The minimum frontage of the plot shall be 3.6 m in
width.
C-2.4 Density
The density norms for plotted development and mixed
development shall be as follows:
Type of Development
a) Plotted development
b) Mixed development
i) Small towns
Range of Densities
(Gross)
65-120 plots per hectare
75-100 dwelling units
per hectare
ii) Cities 100-125 dwelling units
per hectare
iii) Metropolitan Cities 125-150 dwelling units
per hectare
C-2.4.2 In case of developments with per dwelling
unit covered area of 15 m 2 maximum densities of 500
dwelling units per hectare shall be permissible.
C-2.5 Height of Building
The height of building shall not exceed 15 m.
NOTES
1 For buildings up to the height of 15 m, there is no need to
provide lifts.
2 Housing for the low-income group shall preferably be up to
a maximum of two storeys.
3 Buildings for housing beyond 15 m in height should be
resorted to in exceptional circumstances and it should be
governed by provisions laid down in this Code.
C-2.6 Cluster Planning
For size of open cluster and open space, set backs,
vehicular access and pedestrian paths in cluster
planning, the provisions given in Annex E shall apply.
C-3 GENERAL BUILDING REQUIREMENTS
C-3.1 General
The requirements of parts of buildings shall be as given
in C-3.2 to C-3.9.
C-3.2 Plinth
The minimum height of plinth shall be regulated on
the basis of environmental and topographical condition
and higher plinth height may be required in areas prone
to flooding.
C-3.3 Size of Room
C -3.3.1 Habitable Room
Every dwelling unit to be provided should have at least
two habitable rooms. Even if one room house is
provided initially it should be capable of adding a new
second room in future. However, in case single room
tenements are required to be provided where future
additions are not possible, the carpet area of
multipurpose single room should be at least 12.5 m 2 .
Such one room dwelling units with 12.5 m 2 carpet area
of habitable space is permitted only in case of on site
rehabilitation of slum dwellers. In a house of two
rooms, first room shall not be less than 9.0 m 2 with
minimum width of 2.5 m and second room shall not
be less than 6.5 m 2 with^a minimum width of 2.1 m
provided the total area of both the rooms is not less
than 15.5 m 2 . In incremental housing the bigger room
shall always be the first room.
C-3.3.1.1 To facilitate incremental housing in case of
flatted development or otherwise, habitable space at
mezzanine level may be permitted. The minimum size
of such a mezzanine floor should not be lesser than
6.5 m 2 and such a floor should occupy not more than
50 percent of the room area of which it is a part. Such
a mezzanine floor should have appropriate openings
to facilitate light and ventilation as per C-3.6. Minimum
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
43
clear height below and above the mezzanine floor
should be 2.4 m and 2.1 m respectively.
As far as possible mezzanine floor should have direct
ventilation from the external face of the building.
Where this is not possible ventilation through main
room may be allowed provided total area of openings
in the main room is provided taking into consideration
area of mezzanine floor.
Such mezzanine floor may be accessible through the
main room by a ladder, whose minimum angle with
vertical plane should be 22 1 /2°. Height of the riser
should be less than 250 mm.
C-3.3.2 Water Closet/Bathroom
1) The size of independent water-closet shall be
0.90 m 2 with minimum width of 0.9 m;
2) The size of independent bathroom shall be
1.20 m 2 with a minimum width of 1.0 m; and
3) The size of combined bathroom and water-
closet shall be 1.80 m 2 with minimum width
of 1.0 m.
C-3.3.3 Kitchen
The size of a cooking alcove serving as cooking space
shall not be less than 2.4 m 2 with a minimum width of
1.2 m. The size of individual kitchen provided in a
two-roomed house shall not be less than 3.3 m 2 with a
minimum width of 1.5 m.
C-3.3.4 Balcony
The minimum width of individual balcony, where
provided, shall be 0.9 m and shall not be more than
1.2 m and it shall not project beyond the plot line and
on roads or pathway.
C-3.4 Basement
No basement floor shall be allowed.
C-3.5 Minimum Height
The minimum height of rooms/spaces shall be as
follows:
a)
Habitable room
2.6 m
b)
Kitchen
2.6 m
c)
Bath/water-closet
2.1 m
d)
Corridor
2.1 m
C-3.5.1 In the case of sloping roofs, the average height
of roof for habitable rooms shall be 2.6 m and the
minimum height at eaves shall be 2.0 m.
C-3.6 Lighting and Ventilation
The openings through windows, ventilators and other
openings for lighting and ventilation shall be in
accordance with 15.1.2.
NOTE — The windows and other openings shall abut onto
open spaces either through areas left open within the plot or
the front, side and rear spaces provided in the layouts which
shall be deemed to be sufficient for light and ventilation
purposes. Wherever ventilation/lighting is provided by means
of JAU or grill of any material, total area of openings shall
calculated excluding solid portion of the JAU or grill.
C-3.7 Stairs
The following criteria shall be adopted for internal
individual staircase:
a) Minimum Width
1)2 storeyed — straight
0.60 m
2) 2 storeyed — winding
0.75 m
3) 3 or more storeyed —
0.75 m
straight
4) 3 or more storeyed —
0.90 m
winding
b) Riser
200 mm, Max
c) Tread
1) 2 storeyed
225 mm, Min
(see Note)
2) 3 storeyed or more
250 mm, Min
d) Head Room — The minimum
clear head room shall be 2.1 m.
NOTE — This could be reduced to 200 mm as the clear tread
between perpends, with possibility of open riser as well as
nosing and inclined riser to have an effective tread of 225 mm.
C-3.8 Circulation Area
The circulation area on any floor including staircase,
shall not exceed 8 m 2 /dwelling unit.
C-3.9 Water Seal Latrine
No building plan shall be approved and no building
shall be deemed to have been completed and fit for
human occupation unless provision is made for water
seal latrine. No dry latrine shall be allowed. Water seal
latrines can also be provide on the basis of community
toilets or shared toilets as per the recommendation
given in good practice [3(3)].
Where leaching pits are used, it should be constructed
within the premises of the households as it would be
economical as well as facilitate their cleaning. However,
where, due to space constraint, construction of pits
within the premises may not be possible, pits may be
constructed in places like lanes, streets and roads.
In case the pit is located under the road, street or foot
path, the inverted level of the pipe connecting the
latrine pan with the pit shall be at least 1.1 m below
ground level or below the bottom of the water main
existing within a distance of 3 m from the pits
whichever is more. Construction of such pits may be
in accordance with good practice [3(4)].
44
NATIONAL BUILDING CODE OF INDIA
The water seal latrine should be properly maintained
and kept in sanitary condition by the owner or the
occupier. The contents of the septic tanks, soak pits,
leach pits, etc should be periodically emptied.
The leach pits should be cleaned only after 2 years of
their being put out of service after they were full.
C-4 ROADS AND PATHWAYS
The area under roads and pathways in such housing
projects should normally not exceed 20 percent of the
total land area of the project.
Access to the dwelling units, particularly where
motorized vehicles are not normally expected should
be by means of paved footpaths with a right of way
of 6 m and a pathway of 2 m only. The right of way
should be adequate to allow for the plying of
emergency vehicles and also for road side drains and
plantation.
Where pedestrian pathways are not meant for
motorable access to the minimum, right of way of such
pedestrian pathway shall be 3 m. Where houses are
accessible from one side only pathway can be 2 m wide.
The maximum length of such pathways should not be
more than 60 m.
C-5 OTHER REQUIREMENTS
C-5.1 Requirements of fire safety, structural design,
building services and plumbing services shall be as
specified in the Code.
C-5. 2 One water tap per dwelling unit may be
provided, where adequate drinking water supply is
available. If supply is inadequate, public hydrants shall
be provided. In the absence of piped water supply, hand
pumps may be used for provision of water supply.
C-5.3 Recognising the need for informal use of space
for shopping and informal occupation like road side
repairs, pan shops, etc, it is suggested that about Va of
the total shopping area in a layout should be reserved
for such informal uses to cater to the needs of low
income families.
C-5.4 The infrastructural services shall be provided
before the plots are handed over to individual owners.
C-6 SITE AND SERVICES SCHEMES
C-6.1 The developed plot sizes shall be as per C-2.3.1 .
Services would have to be laid by the Agency
concerned as per the provisions of the Code. In so far
as roads and pathways are concerned, they could also
be in line with C-4.
C-6.2 Site and services schemes shall provide for the
following.
a)
b)
c)
d)
Complete infrastructural needs for a
permanent housing, on the periphery of
individual plot or a group/cluster plots;
A service sanitary core in the plot;
A skeletal structure of columns and roof or a
developed plinth; and
Permission to allow temporary construction
on the plot.
While provisions in C-6.2(a) and C-6.2(d) are
essential in site and services projects provisions,
recommendations in C-6.2(b) and C-6.2(c) are
additional provisions depending upon affordability.
ANNEX D
{Clause 12.21)
SPECIAL REQUIREMENTS FOR PLANNING OF PUBLIC BUILDINGS
MEANT FOR USE OF PHYSICALLY CHALLENGED
D-l GENERAL
D-l.l These requirements apply to all buildings and
facilities used by the public. These apply to temporary
or emergency conditions as well as permanent
conditions. It does not apply to private residences.
These requirements are concerned with non-
ambulatory disabilities, semi-ambulatory disabilities,
sight disabilities, hearing disabilities, disabilities of
inco-ordination, aging, allergies, heart and lung
diseases, epilepsy, haemophilia, incontinence and
enterostomy.
It is intended to make all buildings and facilities used by
the public accessible to, and functional for the physically
challenged through and within^heir doors, without loss
of function, space or facility where the general public is
concerned. It supplements the general requirements of
the Code, and reflects greater concern for safety of life
and limb. In cases of practical difficulty, unnecessary
hardship, or extreme differences, the Authority may grant
exceptions from the literal requirements of this Annex or
permit the use of other methods or materials, but only
when it is clearly evident that equivalent facilities and
protection are thereby secured.
D-1.2 For the purpose of this Annex, the following
definitions shall apply.
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
45
D-l.2.1 Aging
Those manifestations of the aging processes that
significantly reduce mobility, flexibility, co-ordination,
and perceptiveness but are not accounted for in the
categories mentioned in D-l.2.3.1 to D-l.2.3.9.
D-l.2.2 Appropriate Number
The number of a specific item that would be necessary,
in accordance with the purpose and function of building
or facility, to accommodate individuals with specific
disabilities in proportion to the anticipated number or
individuals with disabilities who would use a particular
building or facility.
D-l.2.3 Disabilities
D-l.2.3.1 Non-ambulatory disabilities
Impairments that, regardless of cause or manifestation,
for all practical purposes, confine individuals to
wheelchairs.
D-l.2.3.2 Semi-ambulatory disabilities
Impairments that cause individuals to walk with
difficulty or insecurity. Individuals using braces or
crutches, amputees, arthritis, spastics and those with
pulmonary and cardiac ills may be semi-ambulatory.
D-l.2.3.3 Sight disabilities
Total blindness or impairments affecting sight to the
extent that the individual functioning in public areas
is insecure or exposed to danger.
D-l.2.3.4 Hearing disabilities
Deafness or hearing handicaps that might make an
individual insecure in public areas because he is unable
to communicate or hear warning signals.
D-l.2.3.5 Disabilities of inco-ordination
Faulty co-ordination or palsy from brain spinal, or
peripheral nerve injury.
D-l.2.3.6 People with allergies
People with allergies may be sensitive to dust, mildew,
pollen, animal hair, formalin, turpentine, etc. Some are
sensitive to contact with substances and materials, such
as, nickel, chromium and rubber.
D-l.2.3.7 People with heart and lung diseases
People with heart and lung diseases may only be able
to walk short distances and may be unable to climb
stairs. The requirements of these people are similar to
those with impaired mobility.
D-l.2.3.8 People with epilepsy, haemophilia, etc
The requirements of those with epilepsy, heamophilia,
etc, are related primarily to the design of buildings and
the need to minimize the risk of injury caused by falling
or encountering obstacles.
D-l.2.3.9 People with incontinence, enterostomy
operations, etc
The requirements of people with incontinence,
enterostomy operations, etc (colostomies, ileostomies
and urostomies) are mainly related to bathroom
provision. In certain circumstances, for example, in
public water-closet compartments, it may be desirable
to provide a special sink for emptying urine bags.
D-l.2.4 Fixed Turning Radius, Front Structure to Rear
Structure
The turning radius of a wheelchair, left front-foot
platform to right rear wheel, or right front-foot platform
to left rear wheel, when pivoting on a spot.
D-l.2.5 Fixed Turning Radius Wheel
The tracking of the caster wheels and large wheels of
a wheelchair when pivoting on a spot.
D- 1.2.6 Involved (Involvement)
A portion or portions of the human anatomy or
physiology, or both, that have a loss or impairment of
normal function as a result of genesis, trauma, disease,
inflammation or degeneration.
D-l.2.7 Ramps, Ramps with Gradients
Because the term 'ramp' has a multitude of meanings
and uses, its use in this text is clearly defined as ramps
with gradients (gradual slope joining two level
surfaces) that deviate from what would otherwise be
considered the normal level. An exterior ramp, as
distinguished from a 'walk', would be considered an
appendage to a building leading to a level above or
below the existing ground level.
D-l.2.8 Walk, Walks
Because the terms 'walk' and 'walks' have a multitude
of meanings and uses, their use in this standard is
clearly defined as a predetermined prepared surface,
exterior pathway leading to or from a building or
facility, or from one exterior area to another, placed
on the existing ground level and not deviating from
the level of the existing ground immediately adjacent.
D-2 SITE DEVELOPMENT
D-2.1 Almost any building can be made accessible to
physically challenged persons by so planning the site
that the terraces, retaining walls and winding walks
are used effectively.
D-2.1. 1 Site development is the most effective means
to resolve the problems created by topography,
definitive architectural designs or concepts, water table,
existing streets, and typical problems, singularly or
collectively, so that aggress, ingress and egress to
buildings by physically challenged may be facilitated
while preserving the desired design and effect of the
architecture.
46
NATIONAL BUILDING CODE OF INDIA
D-2.2 Walks
D-2.2.1 Public walks should be at least 1 200 mm wide
and should have a gradient not greater than 1 in 20.
D-2.2.1. 1 It is essential that the gradient of walks and
driveways be less than that prescribed for ramps, since
walks would be devoid of handrails and kerbs and
would be considerably longer and more vulnerable to
the elements. Walks of near maximum grade and
considerable length should have level areas at intervals
for purposes of rest and safety. Walks or driveways
should have a non-slip surface.
D-2.2.2 Such walks shall be of a continuing common
surface not interrupted by steps or abrupt changes in level.
D-2.2.3 Wherever walks cross other walks, driveways,
or parking lots they should blend to a common level.
D-2.2.3. 1 This requirement, does not require the
elimination of kerbs, which, particularly if they occur
at regular intersections, are a distinct safety feature for
all of the challenged, particularly the blind. The
preferred method of meeting the requirement is to have
the walk incline to the level of the street. However, at
principal intersections, it is vitally important that the
kerbs run parallel to the street, up to the point where
the walk is inclined, at which point the kerb would
turn in and gradually meet the level of the walk at its
highest point. A less preferred method would be to
gradually bring the surface of the driveway or street to
the level of the walk. The disadvantage of this method
is that a blind person would not know when he has left
the protection of a walk and has entered the hazards of
a street or driveway (see Fig. 9).
D-2.2.4 A walk shall have a level platform at the top
which is at least 1 500 mm long, if a door swings out
onto the platform or towards the walk. This platform
shall extend at least 300 mm beyond each side of the
doorway.
D-2.2.5 A walk shall have a level platform at least
900 mm deep, if the door does not swing onto the
platform or towards the walk. This platform shall extend
at least 300 mm beyond each side of the doorway.
D-2.3 Parking Space
D-2.3.1 Spaces that are accessible and approximate
to the facility should be set aside and identified for use
by individuals with physical disabilities.
D-2.3.2 A parking space open on one side, allowing
room for individuals in wheelchairs or individuals on
braces and crutches to get in and out of an automobile
onto a level surface, is adequate. It should have a
minimum width of 2 700 mm preferably 2 800 mm
for ambulant disabled and minimum 3 000 mm
preferably 3 300 mm for wheel chair users.
D-2.3.3 Parking spaces for individuals with physical
disabilities when placed between two conventional
diagonal or head-on parking spaces should be 3.6 m
to 3.8 m wide and the length of the aisle should 7.3 m,
6.1 m and 6.5 m for head-on, 90° and 60° parking
respectively.
D-2.3.4 Care in planning should be exercised, so that
individuals in wheelchairs and individuals using braces
and crutches are not compelled to wheel or walk behind
parked cars.
D-2.3.5 Consideration should be given to the
distribution of spaces for use by the disabled in
accordance with the frequency and persistency of
parking needs.
D-2.3.6 Walks shall be in conformity with D-2.2.
MAX. GRADIENT 1 IN 10
KERB MAX. 25mm HIGH
Fig. 9 Suitable Method of Blending Pavement and Roadway Surfaces
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
47
D-3 BUILDINGS
D=3.1 Ramps with Gradients
Where ramps with gradients are necessary or desired, they
shall conform to the following requirements (see Fig. 10).
D-3.L1 A ramp when provided should not have a
slope greater than 1 in 20 or maximum of 1 in 12 for
short distance up to 9 000 mm.
D-3. 1,2 A ramp shall have handrails on at least one
side, and preferably two sides, that are 900 mm high,
measured from the surface of the ramp, that are smooth,
and that extend 300 mm beyond the top and bottom of
the ramp. Where major traffic is predominantly
children, the handrails should be placed 760 mm high.
NOTES
1 Where handrails are specified to be of heights other than
80 cm, it is recommended that two sets of handraJS be installed
to serve all people. Where major traffic is predominantly
children, particularly physically disabled children, extra care
should be exercised in the placement of handrails, in
accordance with the nature of the facility and the age group or
groups being serviced (see also D-3).
2 Care should be taken that the extension of the handrails is
no! in itself a hazard. Extension up to 300 mm may be made
on the side of a continuing wall.
D-3. 1.3 A ramp shall have a surface that is non-slip
surface and if length is 3 500 mm, the minimum width
shall be 1 500 mm.
D-3.1.3.1 The provision of non-slip surfaces on ramps
RECESS ENTRANCE DOOR
WHERE IN EXPOSED POSiTiON
1800 x 1800mmMIN.
LEVEL PLATFORM
50 mm KERB
greatly assists the challenged persons with semi-
ambulatory and ambulatory disabilities. Non-slip
surfaces are provided by many finishes and materials.
The surfaces of the concrete ramps can be made non-
skid by brooming the surface or by finishing with an
indenting roller.
D-3.1.4 A ramp shall have a level platform at the top
which is at least 1 800 mm long, if a door swings out
onto the platform or toward the ramp. This platform
shall extend at least 300 mm beyond each side of the
doorway (see Fig. 11).
D-3.1.5 Each ramp shall have at least I 800 mm of
straight clearance at the bottom.
D-3.1.6 Ramps shall have level platforms at 10 m to
12 m intervals for purposes of rest and safety, and shall
have platforms minimum 1.5 m length wherever they
turn.
D-3.1.7 For visually impaired people, ramps may be
colour contrasted with landing.
D-3.1.8 To minimize rise to wheelchair users, ramps
should be equipped with herbs approximately 50 mm
high at exposed sides.
D-3.2 Entrances
D-3.2.1 At least one primary entrance to each building
shall be usable by individuals in wheelchairs (see
Fig. 1 2A) and shall be indicated by a sign (see Fig. 12B).
EXTENDED HANDRAIL AT
HEAD OF RAMP
50 mm KERB TO EXPOSED
SIDE OF RAMP
HANDRAILS
ALTERNATIVE STEPPED
APPROACH WHERE RAMP
GRADIENT EXCEEDS 1 IN 12
TREAD MIN. 300 mm
RISERS MAX. 150 mm
RAMP WITH SLOPE NOT
GREATER THAN 1 IN 20
OR MAXIMUM OF 1:12
FOR SHORT DISTANCE
EXTENDED HANDRAIL
AT FOOT OF RAMP
Fig. 10 Example of Ramped Approach
48
NATIONAL BUILDING CODE OF INDIA
r300 min
1
1800-^— |ar 1800
1
RAMP
UP OR
DOWN t
1800
All dimensions in millimetres.
Fig. 11 Level Areas Required at End of Ramps Leading to Doorways
-ORANGE
.(LUMINOUS COLOUR)
WHITE
BLACK-
12A PLAN OF DOORS
SUITABLE FOR THE
WHEELCHAIR BOUND
12B SIGN FOR USE AT
THE ENTRANCE
Fig. 12 Entrances
D-3.2.2 At least one entrance usable by individuals
in wheelchairs shall be on a level that would make the
elevators accessible.
D-3.3 Doors and Doorways
D-3.3.1 Doorwidth
To enable wheelchair users to pass through doors, the
minimum clear width should be 900 mm and shall be
operable by a single effort. In certain cases the clear
width should be 900 mm to 1 000 mm; for example, if
the wheelchair has to be turned in the doorway, where
there is a door-closer or at entrance doors to public
buildings and in other situations where there is
considerable traffic.
D-3.3.1.1 Two-leaf doors are not usable by those with
disabilities defined in D-l.2.1, D-l.2.2 and D-l.2.5
unless they operate by a single effort, or unless one of
the two leaves meets the requirements of D-3.3.1.
D-3.3.1.2 Side-hung doors
To facilitate wheelchair manoeuvre, doors should be
hung with the hinges in room corners. Doors opening
out into corridors or circulation spaces should be
avoided as far as possible.
D-3.3.1.3 It is recommended that all doors have kick
plates extending from the bottom of the door to at least
400 mm from the floor, or be made of a material and
finish that would safely withstand the abuse they might
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
49
receive from canes, crutches, wheelchair foot-
platforms, or wheelchair wheels.
D-3.3.2 Wheelchair Manoeuvring Space
To enable wheelchair users to approach doors
manoeuvring space is needed as shown in the Fig. 13.
A corridor should have a width of at least 1 200 mm to
allow a 90° turn to be made through a door. In narrow
spaces sliding doors may be preferable.
8
b
450
1500
550
1400
All dimensions in millimetres.
NOTE — Depending on the free space beside the opening side
(450 or 550 mm), the depth of free space should be 1 500 or
1 400 mm.
Fig. 13 Manoeuvring Space Needed for
Wheelchair Users to Approach Doors
D-3.3.3 Thresholds
Raised thresholds should be avoided, but where this is
not possible, their height should not exceed 25 mm.
Rubber thresholds are advantageous for wheelchair
users.
D-3.3.3. 1 Care should be taken in the selection,
placement and setting of door closers so that they do
not prevent the use of doors by the physically disabled.
Time-delay door closers are recommended.
D-3.3.3.2 Self-closing doors
Wheelchair users and other with impaired mobility
have difficulty in using self-closing doors. The force
required to open them should be reduced as far as
possible. Public buildings should preferably have
sliding automatic doors.
D-3.3.4 Door Identification
To help people with impaired vision to see doors, the
door and frame should be in a colour which contrasts
with the adjoining wall. Glass or glazed doors should
be marked with a coloured band or frame, a little below
eye-level.
D-3.3.5 Handles
Door handles and locks should be easy to manipulate.
To facilitate the closing of a door by wheelchair users
(for example, a water-closet compartment), the door
should have a horizontal handle approximately 800 mm
from the floor. Self-closing doors should be equipped
with an easy gripped vertical pull-handle with a
length of at least 300- mm, and with the lower end
approximately 800 mm above floor. For many people
and specially those with impaired vision, it is helpful
to make clear whether doors are to be pulled or pushed
(see Fig. 14).
AH dimensions in millimetres.
fte. 14 Position of Handle
D-3.4 Windows
Windows should be designed to avoid the glare which
is a particular problem for people with impaired
vision. Large glass areas close to circulation spaces
should be marked a little below eye-level with a
coloured band or frame. To enable wheelchair users
to see through a window comfortably, the sill should
be not higher than 800 mm from the floor. Windows
should be easy to open and close. Their controls
should be placed in the zone 900 to 1 200 mm from
the floor (see Fig. 15).
50
NATIONAL BUILDING CODE OF INDIA
All dimensions in millimetres.
Fig. 15 Position of Sill and Window Control
D-3.5 Stairs
Stairs should not be the only means of moving between
floors. They should be supplemented by lifts or ramps.
D-3.5. 1 Straight flights of steps are preferred
by ambulant disabled people. Treads should be
approximately 300 mm deep and risers not higher than
150 mm. Steps should be of a consistent height and
depth throughout the stair. Projecting nosings and open
stairs should be avoided to minimize the risk of
stumbling.
D-3.5.2 Handrails should be provided to both sides
of any stairway. They should be continuous and extend
not less than 300 mm beyond the top and bottom step
(otherwise it is difficult for the disabled to use the rail
at the first and last step; see Fig. 16).
D-3.5.3 For people with impaired vision, there should
be a colour contrast between landings, and top and
bottom steps of a flight of steps, or the front edge of
each step should have a contrasting colour.
D-3.6 Floors
D-3.6.1 Floors shall have a non-slip surface.
D-3.6.2 Floors on a given storey shall be of a common
level through out or be connected by a ramp in
accordance with D-3.1.1 to D-3.1.8.
D-3.6.2.1 A gentle slope up to 10 mm may be given
between the level of the floor of the corridor and the
level of the floor of the toilet rooms.
D-3.6.2.2 There should not be a difference between
the level of the floor of a corridor and the level of a
meeting room, dining room, or any other room, unless
proper ramps are provided.
D-3.7 Sanitary Facilities
It is essential that sanitary facilities, in accordance with
the nature and use of a specific building or facility, be
made accessible to, and usable by, the physically
challenged.
D-3.7.1 Sanitary facihties shall have space to allow traffic
of individuals in wheelchairs (see Fig. 17 and 18).
All dimensions in millimetres.
Fig. 16 Extension of Handrail in Stairs
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
51
VERTICAL
RAIL
ALTERNATIVE
FOR DOOR
RISING BUTT
HINGES
455
1370 mm mln. OR 1520 mm WHERE
DEPTH IS LESS THAN 1750 mm OR
DOOR IN ALTERNATIVE POSITION
TOILET PAPER
HOLDER
WASH HAND BASIN WITH
TOWEL DISPENSER OVER
RiM AT 810 mm ABOVE
FLOOR
VERTICAL
RAIL
All dimensions in millimetres.
Fig. 17 Suggested Plan of WC Compartment for the Wheelchair Bound
RAIL AT 280 mm
ABOVE WC SEAT -
PAPER
TOWEL
DISPENSER
TOILET
PAPER
HOLDER
li
VERTICAL RAIL
835mm TO 1295 nrmnT
ABOVE FLOOR
BASIN RIM AT
780 mm
WC SEAT AT ABOVE FLOOR
500mm
ABOVE FLOOR
-i tz:
O
UJ
2*8
<
AH dimensions in millimetres.
Fig. 18 Section Through WC Compartment for the Wheelchair Bound
52
NATIONAL BUILDING CODE OF INDIA
D-3.7.2 Sanitary facilities shall have at least one water-
closet cubical for the ambulant disabled (see Fig. 19
and 20), that:
a)
b)
c)
d)
e)
is 900 mm wide;
is at least 1 500 mm, preferably 1 600 mm deep;
has a door (where doors are used), that is,
800 mm wide and swings out;
has handrails on each side, 780 mm high and
parallel to the floor, 40 mm clearance between
rail and wall, and fastened securely at ends
and centre; and
has a water-closet with the seat 500 mm from
the floor.
NOTE — The design and mounting of the water-closet
is of considerable importance. A wall-mounted water-
closet with a narrow understructure that recedes sharply
is most desirable. If a floor mounted water-closet must
be used, it should not have a front that is wide and
perpendicular to the floor at the front of the seat. The
bowl should be shallow at the front of the seat and turn
backwards more than downwards to allow the individual
in a wheelchair to get close to the water-closet with the
seat of the wheelchair.
D-3.7.3 Sanitary facilities shall have wash basins with
narrow aprons, which when mounted at standard height
are usable by individuals in wheelchairs; or they shall
have wash basins mounted higher, when particular
designs demand, so that they are usable by individuals
in wheelchairs.
D-3.7.3.1 The drain pipes and hot-water pipes under
a sanitary appliance shall be covered or insulated so
that a wheelchair individual do not find it inconvenient.
D-3.7.4 Some mirrors and shelves shall be provided
above the wash basins at a height as low as possible
and not higher than 1 m above the floor, measured
from the top of the shelf and the bottom of the mirror.
D-3.7.5 Sanitary facilities for men shall have wall-
mounted urinals with the opening of the basin 460 mm
from the floor, or shall have floor-mounted urinals that
are on level with the main floor of the toilet room.
D-3.7.6 Toilet rooms shall have an appropriate number
of towel racks, towel dispensers, and other dispensers
and disposal units mounted not higher than 910 mm
from the floor.
D-3.8 Drinking Fountains
An appropriate number of drinking fountains or other
water-dispensing means shall be accessible to and
usable by the physically disabled.
D-3.8.1 Drinking water fountains or water coolers
shall have up front spouts and control.
TOILET PAPER
HOLDER
HORIZONTAL RAIL AT
280 mm ABOVE WC
SEAT LEVEL
■ \/y
VERTICAL RAIL
1295 mm HIGH
RECOMMENDED
EXTENSIONTO
HORIZONTAL RAIL
HORIZONTAL
PULL RAIL
Fig* 19 Suggested Plan WC Compartment for the Ambulant
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
53
280 mm
RAIL AT 280 mm
ABOVE WC SEAT
^ TOILET PAPER
VERTICAL RAIL c
835mm TO 1295 mm
ABOVE FLOOR
i
WC SEAT AT
500 mm
ABOVE FLOOR
a:
■=*lS!
Fig. 20 Section Through WC Compartment for the Ambulant Disabled
D-3.8.2 Drinking water fountains or water coolers
shall be hand-operated or hand and foot-operated.
D-3.8.2. 1 Conventional floormounted water coolers
may be convenient to individuals in wheelchairs if a
small fountain is mounted on the side of the cooler
800 mm above the floor.
D-3.8.2.2 Fully recessed drinking water fountains are
not recommended.
D-3.8.2.3 Drinking water fountains should not be set into
an alcove unless the alcove is wider than a wheelchair.
D-3.9 Public Telephones
An appropriate number of public telephones should be
made accessible to and usable by the physically disabled.
NOTE — The conventional public telephone booth is not
usable by most physically disabled individuals. There are many
ways in which public telephones may be made accessible and
usable. It is recommended that architects and builders confer
with the telephone companies in the planning of the building
or facility.
D-3.9.1 Such telephones should be kept so that the dial
is placed at minimum 1 200 mm from floor and the
handset may be reached by individuals in wheelchairs.
D-3.10 Handrails
Handrails are used as a locational and mobility aid by
blind and visually impaired people, and as a support for
people with mobility impairments. The handrail should
be securely fitted to the wall to withstand heavy pressure.
Handrails should turn in towards the wall at either end.
D-3.10.1 Handrails should be approximately 900 mm
from the floor. The rail should be easy to grip, having
a circular section with a diameter of approximately
40 mm and fixed as shown in Fig. 21.
120
1
jj
All dimensions in millimetres.
Fig. 21 Fixing of Hand Rail
54
NATIONAL BUILDING CODE OF INDIA
D-3.10.2 To aid indentification, the colour of the rail
should contrast with the wall behind.
D-3.11 Elevators
In a multi-storey building, elevators are essential to
the successful functioning of physically disabled
individuals. They shall conform to the requirements
given in D-3.11.1 and D-3.11.2.
D-3.11.1 Elevators shall be accessible to, and usable
by the physically disabled on the level that they use to
enter the building, and at all levels normally used by
the general public.
D-3.11.2 Elevators shall allow for traffic by wheelchairs
(see also D-3.3).
D-3.12 Controls
It is advantageous for wheelchair users if controls are
placed at low level. For visually impaired people, they
should be at eye-level.
D-3.12.1 To enable wheelchair users to reach controls
while not placing them too low for visually impaired
people, controls should be in the zone 900 mm to
1 200 mm from the floor. It is advantageous if controls
in, for example, lifts are placed at an angle of
approximately 45° to the wall so that they are easier to
read and operate. To cater for wheelchair users,
controls should be placed not less than 400 mm from
room corners. All the power and electric points should
be placed at one metre above the floor level and should
not project outside walls.
D-3.12.2 Again, to cater for visually impaired people,
controls should be colour-contrasted with
backgrounds. Information should preferably be in relief
for tactile reading.
D-3.12.3 To aid operation for people with impaired
co-ordination or impaired vision, switches, etc, should
have large push plates.
D-3.12.4 Controls for powered door openers to hinged
doors should be located so that the doors do not conflict
with wheelchairs, sticks, walking aids, etc.
D-3.12.5 To facilitate operation for people with
limited strength in arms and hands, handles should be
easy to grip and turn.
D-3.13 Identification
Appropriate identification of specific facilities within
a building used by the public is particularly essential
to the blind.
D-3.13.1 Raised letters or numbers shall be used to
identify rooms or offices.
D-3.13.2 Such identification should be placed on the
wall, to left of the door, preferably at a height of
1 500 mm from the floor.
D-3.13.3 Doors that are not intended for normal use,
and that might prove dangerous if a blind person were
to exit or enter by them, should be made quickly
identifiable to the touch by knurling the door handle
or knob (see Fig. 22).
KNURLINGS
Fig. 22 Door Handle
D-3.14 Warning Signals
D-3.14.1 Audible warning signals shall be accompanied
by simultaneous visual signals for the benefit of those
with hearing disabilities.
D-3.14.2 Visual signals shall be accompanied by
simultaneous audible signals for the benefit of the
blind. To assist blind people, lettering and symbols on
signs should be in relief for tactile reading.
D-3.14.3 Signs should be designed and located so that
they are easy to read. For visually impaired people,
signs should preferably be at eye-level and it should
be possible to approach them closely. Text and symbols
should be colour-contrasted with the background. The
letters should not be less than 12 mm high.
D-3.14.4 Signs should pe well illuminated and
surfaces should not cause mirroring or reflections.
Signs should not be behind glass or similar materials.
D-3.14.5 Information baspd on colour codes only
should be avoided; colourblind people may find them
difficult to understand.
D-3.15 Work Bench
This should be at least 800 mm wide, 600 mm deep
and 650 mm to 700 mm high. For wheelchair users,
the convenient height of work tops is between
750 mm and 850 mm; flexible provision is preferred.
Further, for wheelchair access to a work bench, wash
basin or table, a clear space for knees and footrests is
needed.
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BLTLDING REQUIREMENTS
55
D-3.16 Hazards
Every effort shall be exercised to obviate hazards to
individuals with physical disabilities.
D-3.16.1 Access panels or manholes in floors, walks,
and walls may be extremely hazardous, particularly
when in use, and should be avoided.
D-3.16.2 When manholes or access panels are open
and in use, or when an open excavation exists on a
site, particularly when it is in proximity of normal
pedestrian traffic, barricades shall be placed on all open
sides, at least 8.5 m from the hazard, and warning
devices shall be installed in accordance with D-3.14.2.
D-3.16.3 Low-hanging door closers that remain within
the opening of a doorway, when the door is open or
that protrude hazardously into regular corridors or
traffic ways when the door is closed, shall be avoided.
D-3.16.4 Low-hanging signs, ceiling lights, and
similar objects or signs and fixtures that protrude into
regular corridors or traffic way shall be avoided. A
minimum height of 2.1 m measured from the floor is
recommended.
D-3.16.5 Ramps shall be adequately lighted.
D-3.16.6 Exit signs shall be in accordance with good
practices [3(5)].
D-3.16.7 Equipment and materials causing allergic
reactions should as far as possible be avoided in
dwellings and buildings.
D-4 DESIGNING FOR CHILDREN
The dimensions given in this Annex are for adults of
average stature. In designing buildings for use by
children, it may be necessary to alter some dimensions,
such as, height of handrails, in accordance with
accepted standards [3(6)].
D-5 For additional information regarding other
facilities and conveniences required in buildings meant
for use of physically challenged, reference may be
made to accepted standards [3(7)].
ANNEX E
(Clauses 12.22, C-2.3.1 and C-2.6)
SPECIAL REQUIREMENTS OF CLUSTER PLANNING FOR HOUSING
E-l GENERAL
E-1.1 These guidelines cover planning and building
requirements of housing developed as clusters. These
requirements are applicable to all housing projects
taken up by public, private or co-operative agencies.
E-2 PLANNING
E-2.1 Plot Size
The minimum plot size permissible shall be 15 m 2 with
100 percent ground coverage and an FSI of two.
Hundred percent ground coverage and FSI of 2 will
be applicable up to plot size of 25 m 2 . For plot sizes
beyond 25 m 2 , provision in accordance with good
practice [3(1)] shall be applicable.
E-2.2 Plot/Plinth Area for Slum Resettlement on
Same Site
In case of slum resettlement on the same site, minimum
area may be reduced to 12.5 m 2 with potential for adding
another 12.5 m 2 on first floor with an internal staircase.
E-2.3 Group Housing
Group housing may be permitted within cluster housing
concept. However, dwelling units with plinth areas up
to 20 m 2 should have scope for adding a habitable
room. Group housing in a cluster should not be more
than 15 m in height.
E-2.4 Size of Cluster
In ground and one storeyed structures not more than
20 houses should be grouped in a cluster. Clusters with
more dwelling units may create problems relating to
identity, encroachment and maintenance.
E-2.5 Size of Cluster Open Space
Minimum dimensions ofopen spaces shall be not less
than 6 m or 3/4th of the height of buildings along the
cluster open space, whichever is higher. The area of
such cluster court shall not be less than 36 m 2 . Group
housing around a cluster open space should not be
normally more than 15 m in height. Maximum cluster
courtyard width and breadth shall be 13 m.
E-2.6 Setbacks
No setbacks are needed from the edges of cluster as
pedestrian/vehicular access roads surrounding the
cluster.
56
NATIONAL BUILDING CODE OF INDIA
E-2.7 Right to Build in Sky
Pedestrian paths and vehicular access roads to clusters
separating two adjacent clusters may be bridged to
provide additional dwelling units. While bridging the
pedestrian path way minimum clearance should be one
storey height; length of such bridging should be not more
than two dwelling units. While bridging the vehicular
access roads minimum clearance should be 6 m.
E-2.8 Vehicular Access
A right of way of at least 6 m width should be provided
up to the entrance to the cluster to facilitate emergency
vehicle movement up to cluster.
E-2.9 Pedestrian Paths
Minimum width of pedestrian paths shall be 3 m.
E-2.10 Width of Access Between Two Clusters
Built area of dwelling unit within cluster shall have no
setbacks from the path or road, space. Hence, the height
of the building along the pathway or roads shall be not
less than 60 percent of the height of the adjacent
building subject to minimum of 3 m in case of pathway
and 6 m in case of vehicular access.
E-2.11 Density
Cluster planning methodologies result in higher
densities with low rise structures. With per dwelling
unit covered area of 15 m 2 densities of 500 dwelling
units per hectare (net) shall be permissible. Densities
higher than this should not allowed.
E-2.12 Group Toilet
Cluster housing for economically weaker section
families can have group toilets at the rate of one water-
closet, one bath and a washing place for three families.
These shall not be community toilets, as keys to these
toilets shall be only with these three families, making
them solely responsible for the maintenance and
upkeep of these toilets.
E-3 OTHER REQUIREMENTS
E-3.1 Requirements of Building Design
With the exception of clauses mentioned above,
requirements of building will be governed by the
provision of this Code and good practice [3(1)].
E-3.2 Requirements of fire safety, structural design,
building services and plumbing services shall be as
specified in this Code.
ANNEX F
(Clause 12.23)
SPECIAL REQUIREMENTS FOR LOW INCOME HABITAT PLANNING
IN RURAL AREAS
F-l GENERAL
F-l.l These guidelines cover planning and general
building requirements for low-income houses having
a maximum built-up area of 40 m 2 including future
expansion, built on notified (as notified by the State
Governments) rural areas. The provisions on layout
planning of low-income housing colonies in rural areas
are applicable to public and private agencies/
government bodies. The provisions of this Code on
design and construction of buildings for low income
housing in approved layouts are applicable to all private
and public agencies.
F-2 SETTLEMENT
PLANNING
AND ENVIRONMENT
F-2.1 While planning for rural settlements the
following factors shall be taken into consideration:
a) Ecosystem and Biodiversity.
b) Topography with its direct effect on climate,
likelihood of natural disasters, natural
drainage, etc.
c) Identity of the place rooted in its culture and
heritage.
d) Nearness and connectivity with nearby urban
centres.
e) Occupation related requirements.
f) Water management
g) Waste management,
h) Land tenure.
j) Site selected shall be conveniently
approachable and suitably developed and
shall not be subjected to water logging/
flooding.
k) Plot size
m) Density (Gross)
n) Minimum frontage
80 m 2 , Min
60 plots per hectare,
Max
6m
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
57
p) Ground Coverage
q)
r)
s)
Floor area ratio (FAR) :
Open spaces
t)
33 percent (subject to
a maximum of 50
percent)
2, Max
1.21 hectare open
space for a village
with 200 houses.
Facilities like branch of co-operative bank, a
fertilizer depot, a veterinary hospital, market
place and a branch of the co-operative
consumer store besides facilities for
educational and health care should be
available within a maximum distance of 5 km
from any settlement.
Proposed Road Hierarchy
Road Road
Road
Function/Remarks
Type Description
Width
(1) (2)
(3)
(4)
Ri
R2
R3
Road which
connects
village to
nearby areas
Road which
take major
traffic to the
village
9 m Widest road
6 m
Internal
village road
R4 Internal
village road
Main village roads
with drain on both
sides to facilitate
drainage system of
the village
4.5 m Other village roads
3 m Village lanes
F-3 GENERAL BUILDING REQUIREMENTS
(HOMESTEAD)
F-3.1 General
The requirements of parts of buildings shall be as given
in F-3.2 to F-3.7.
F-3.2 Plinth
The minimum height of plinth shall be regulated on
the basis of environmental and topographical condition
and higher plinth height may be required in areas prone
to flooding.
F-3.3 Size of Room
F-3.3.1 Habitable Room
Every dwelling unit to be provided should have at least
two habitable rooms. Even if one room house is
provided initially it should be capable of adding a new
second room in future. In a house of two rooms, first
room shall not be less than 9.0 m 2 with minimum width
of 2.5 m and second room shall not be less than 6.5 m 2
with a minimum width of 2. 1 m provided the total area
of both the rooms is not less than 15.5 m 2 . In
incremental housing the bigger room shall always be
the first room.
F-3.3. 1.1 To facilitate incremental housing in case
of flatted development or otherwise, habitable space
at mezzanine level may be permitted. The minimum
size of such a mezzanine floor should not be lesser
than 6.5 m 2 and such a floor should occupy not more
than 50 percent of the room area of which it is a part.
Such a mezzanine floor should have appropriate
openings to facilitate light and ventilation as
perF-3.5. Minimum clear height below and above
the mezzanine floor should be 2.4 m and 2.1 m
respectively.
As far as possible mezzanine floor should have direct
ventilation from the external face of the building.
Where this is not possible ventilation through main
room may be allowed provided total area of openings
in the main room is provided taking into consideration
area of mezzanine floor.
Such mezzanine floor may be accessible through the
main room by a ladder, whose minimum angle with
vertical plane should be 22 1 /2°. Height of the riser
should be less than 250 mm.
F-3.3.2 Water-Closet/Bathroom
a) The size of independent water-closet shall be
0.9 m 2 ; with minimum width of 90 cm.
b) The size of independent bathroom shall be
1.2 m 2 with minimum width of lm, and
c) The size of combined bath and water closet
shall be 1.8 m 2 with minimum width of 1 m.
F-3.3.3 Kitchen
The size of a cooking alcove serving as cooking space
shallnot be less than 2.4 m 2 with a minimum width of
1 .2 m. The size of individual kitchen shall not be less
than 3.3 m 2 with a minimum width of 1.5 m. Semi-
open spaces with low walls and roof may also be
provided for cooking in areas where such provision is
suitable with respect to climatic comfort. Provision for
smokeless CHULLHA shall be made in all kitchens
considering fuel efficiency and health hazard due to
smoke inhalation.
F-3.3.4 Balcony
The minimum width of individual balcony, where
provided, shall be 0.9 m and shall not be more than
1.2 m and it shall not project beyond the plot line and
on roads or pathway.
F-3.4 Minimum Height
The minimum height of rooms/spaces shall be as
follows:
58
NATIONAL BUILDING CODE OF INDIA
a) Habitable room
b) Kitchen
c) Bath/water-closet
d) Corridor
2.75 m
2.6 m
2.2 m
2.1m
F-3.4.1 In the case of sloping roofs, the average height
of roof for habitable rooms shall be 2.75 m and the
minimum height at eaves shall be 2.10 m.
F-3.5 Lighting and Ventilation
The openings through windows, ventilators and other
openings for lighting and ventilation shall be as per in
accordance with 15.1.2.
NOTE — The windows and other openings shall abut onto
open spaces either through areas left open within the plot or
the front, side and rear spaces provided in the layouts which
shall be deemed to be sufficient for light and ventilation
purposes. Wherever ventilation/lighting is provided by means
of JALJ or grill of any material, total area of openings shall
calculated excluding solid portion of the JALJ or grill.
F-3.6 Stairs
The following criteria shall be adopted for internal
individual staircase:
a) Minimum width
1) 2 storeyed-straight 0.60 m
2) 2 storeyed-winding 0.75 m
3) 3 or more storeyed-straight 0.75 m
4) 3 or more storeyed-winding 0.90 m
b) Riser 200 mm, Max
c) Tread
1) 2 storeyed 225 mm, Min
2) 3 storeyed or more 250 mm, Min
NOTE — This could be reduced to 20 cm as the clear tread
between perpends, with possibility of open riser as well as
nosing and inclined riser to have an effective going of
22.5 cm.
F-3.7 Water Seal Latrine
No building plan shall be approved and no building
shall be deemed to have been completed and fit for
human occupation unless provision is made for water
seal latrine. No dry latrine shall be allowed. Water seal
latrines can also be provide on the basis of community
toilets or shared toilets as per the recommendation
given in [3(3)].
Where leaching pits are used, it should be constructed
within the premises of the households as it would be
economical as well as facilitate their cleaning. However,
where, due to space constraint, construction of pits
within the premises may not be possible, pits may be
constructed in places like lanes, streets and roads.
In case the pit is located under the road, street or foot
path, the inverted level of the pipe connecting the
latrine pan with the pit shall be at least 1.1m below
ground level or below the bottom of the water main
existing within a distance of 3 m from the pits
whichever is more. Construction of such pits may be
in accordance with [3(4)].
The water seal latrine should be properly maintained
and kept in sanitary condition by the owner or the
occupier. The contents of the septic tanks, soak pits,
leach pits, etc, should be periodically emptied.
The leach pits should be cleaned only after 2 years of
their being put out of service after they were full.
Location of sanitary facility either as part of the house
or separately shall be decided on the basis of felt
perceptions.
F-3.8 The house site shall provide space for storage of
food grains and keeping cattle. A manure pit having a
minimum area of 1.0 m 2 shall also be catered for. This
will take care of composting of biodegradable waste.
F-4 OTHER REQUIREMENTS
F-4.1 Requirements of fire safety, structural design,
building services and plumbing services shall be as
specified in relevant parts of the Code.
F-4.2 One water tap per dwelling unit may be
provided, where adequate drinking water supply is
available. If supply is inadequate, public hydrants shall
be provided. In the absence of piped water supply, hand
pumps may be used for provision of water supply.
F-4.3 Drainage System
F-4.3.1 Water from drains shall be connected to
village ponds and appropriate eco-friendly methods
like growing of duck weed plants shall be adopted to
treat waste water.
F-4.3.2 This treated water may be used for irrigation
and agriculture.
F-4.4 Appropriate methods (namely conservation,
ground water recharging, rain water harvesting, etc.)
should be employed to ensure effective water
management.
F -4.5 Community Facilities
F-4.5.1 A community hzlUBARAAT GHAR shall be
established.
F-4.5.2 Rural Development Centre shall include
PANCHAYAT GHAR, a MAHILA KENDRA that may
also serve as a vocational training centre.
F-4.5.3 School, health centre, post office, police post,
shopping, work sheds for the artisans, telephone
facilities, etc should also be established.
F-4.6 The use (to the extent possible) of locally
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
59
available building materials and cost effective
substitutes for scarce building materials. Appropriate
technology inputs shall be introduced for improving
the local materials or conventional or traditional
practices for improved efficiency.
F-4.7 The concept of 'aided self-help' shall be ensured
for active participation of the prospective users and
association in the construction and development of
dwelling units and other community building.
F-4.8 The special needs of women headed households/
single and working women/woman in difficult
circumstances should be addressed. The specific
requirement of women in terms of providing necessary
facilities in homes to lessen their drudgery would be
given sufficient attention.
F-4.9 Protecting and promoting our cultural heritage,
architecture and traditional skills should be given due
importance.
ANNEX G
(Clause 12.24)
SPECIAL REQUIREMENTS FOR DEVELOPMENT PLANNING IN HILLY AREAS
G-l GENERAL
G-l.l These guidelines provides requirements relating
to development planning and design of buildings in
hilly areas. Any area above 600 m in height form mean
sea level may be classified as hilly, or any area with
average slope of 30° may also be classified as hilly,
considering the sensitive and fragile eco-system of hills
and mountains. However, the State Governments
may identify and notify areas to be covered under
'Hilly Area', which need to be dealt with special
consideration, when developmental activities are
taken up.
G-l. 2 Hilly areas have one of the most fragile eco-
systems, which need to be conserved. Therefore
planning and development strategies for hilly areas
shall have to be designed with added sensitivity and
stress on integrated development. The development
approach shall comprise sound land use planning and
settlement planning.
G-1.3 Settlement planning in the hill areas has
extremely large implications on the environment. For
planning of the new settlements or working out the
strategies for the growth of the existing settlements, it
is necessary to conduct detailed environmental
inventory/impact assessment. The inventory would
involve geological investigations, slope analysis, soil,
flora and fauna analysis, climatic inventories,
vulnerability to natural disasters, etc. In addition to
this the aesthetic factors, cultural, architectural and
historical heritage, scenic/landscape value should also
be taken into consideration. Keeping in view the
scarcity of good buildable land and also the high cost
of the construction, it is necessary to optimize the use
of land and at the same time, use cost effective,
appropriate building materials and technologies.
G-2 LAND USE PLANNING
G-2.1 The following land use structure shall be
adopted in Development Planning in Hilly areas:
Land Use
(1)
Percentage of Developed Area
Small Towns
Medium Towns
Large Cities
(2)
(3)
(4)
50-55
48-52
45-50
2-3
2-3
4-5
3-4
4-5
5-7
8-10
8-10
12-15
15-18
15-18
18-20
5-6
5-6
6-8
8-10
8-10
8-10
Residential
Commercial
Industrial
Public and semi-public
Recreational
Transport and commerce
Ecological
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NATIONAL BUILDING CODE OF INDIA
G-3 OPEN SPACES
G-3.1 The following standards shall be adopted in Development Planning in Hilly areas.
Type
(1)
Area Range Area per 1 000
Population
(in ha) (in ha)
(2) (3)
Remarks
(4)
Tot lot
0.03-0.05
—
Playground
0.50-1.00
0.12 to 0.20
Parks
1.20-2.00
0.12 to 0.20
City parks/playgrounds/ma/dan/
exhibition grounds/cultural
gathering grounds
0.12 to 0.20
Botanical garden
10-20
—
Recreational complex
including zoo
10-12
—
Minimum width 15 m
One for every 5 000 may be combined
with schools.
One for every 10 000 population.
For the entire town at one of more sites,
depending upon design and space
availability.
One for every town
One for every settlement with tourist
potential
G-4 ROADS AND PATHS
G-4.1 Street orientation shall preferably be East- West
to allow for maximum South sun to enter the buildings.
The street shall be wide enough to ensure that the
buildings on one side do not shade those on the other
side.
G-4.2 The following road widths shall be adopted for
urban roads in Hilly areas.
Road Type
Width (in m)
Open Areas
Built-up Areas
Plains
(1)
(2)
(3)
(4)
Arterial road
18-24
15-18
50-60
Sub-arterial road
15-18
12-15
30-40
Collector road
9-12
7.5-9
20-30
Local street
4.5-6
3-6
10-20
Loop street (maximum length =
= 500
m)
4.5
4.5
9
Cul-de-sac (maximum length =
= 500
m)
4.5
4.5
7.5
Pedestrian path
1.5-2.5
1-1.5
1.5-4.5
G-4.3 Hill Road Manual (IRC:SP:48-1998), a
publication of the Indian Roads Congress shall be
referred to for detailed guidelines for planning roads
in Hilly areas.
G-5 COMMUNITY FACILITIES AND SERVICES
G-5.1 The following standards shall be adopted for
community facilities and Services in Hilly areas.
Type
(1)
Population
Distance
Area Range
(in ha)
(2)
(3)
(4)
4 000
1-2
0.20 to 0.30
15 000
5-7
0.30 to 0.50
—
8-12
0.30 to 0.60
30 000
8-12
2.00 to 3.00
Educational
Primary school
Secondary school (10+2)
Industrial training centre
College
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
61
Type
Population
Distance
Area Range
(in ha)
(1)
(2)
(3)
(4)
B. Health
Health sub-centre
Primary health centre
(25-50 beds)
Hospital (200-250 beds)
Veterinary centre
C Other facilities
Community welfare centre
D. Services
Fire station
General post office
Post office
Rural post office
Rural post office
Bank (tribal areas)
Telephone exchange
Electric sub-station (66 kV)
Electric sub-station (11 kV)
LPG godown
3000
2-4
0.025 to 0.067
20000
16-20
0.105 to 0.210
80000
16-20
0.840 to 2.100
1000
16-20
0.050 to 0.100
16 000
5-7
0.10 to 0.15
50 000
_
0.30 to 0.80
50 000
10-15
0.20 to 0.40
10 000
5-7
0.10 to 0.15
2 000
2-4
0.025 to 0.050
1000
1-2
—
10 000
16-20
0.100 to 0.150
50 000
10-15
0.20 to 0.40
—
—
1.00
__
—
0.05
—
—
0.15
G-6 GENERAL BUILDING REQUIREMENTS
G-6.1 General
The provisions contained in this Part shall
apply excepting for the specific provisions given
hereunder.
G-6.2 Siting
G-6.2.1 No house shall preferably be located closer
than 1 m to another house.
G-6.2.2 No house shall be located closer than 10 m
to a steep slope.
G-6.2.3 No house shall be built on a landfill or on the
edge of a slope known to have been levelled.
G-6.2.4 Buildings in hills shall be clustered together
to minimise the exposure to cold winds. Open spaces
provided shall allow for maximum South sun.
G-6.2.5 Buildings shall be located on the south slope
of a hill or mountain for better exposure to solar
radiation. At the same time, exposure to cold winds
may be minimized by locating the building on the
leeward side.
G-6.3 Passive Systems for Climatic Control
G-6.3.1 Appropriate solar passive methods, such as
orientation, double-glazing, trombe walls and solar
collectors, shall be adopted to achieve climatic comfort
with little use of conventional energy.
G-6.3.2 Care shall be taken in siting and design of
buildings to provide passive controls to modify the
effect of cold/strong winds.
G-6.4 Flat land is normally not available in hilly
regions. The houses are required to be constructed on
partially sloping land made available by cutting and
filling. It shall be necessary to protect the house by
building retaining walls/breast walls [see 3(8)] to avoid
landslides occurring at time of earthquakes or heavy
rains.
G-6.5 Disaster Resistance
All necessary steps shall be taken in designing and
building in hilly regions to achieve disaster resistance
as per the relevant codes and Part 6 'Structural Design' .
All natural disasters likely to affect the locality shall
be taken into consideration, namely earthquakes,
cyclones, avalanches, flash floods, landslides etc.
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NATIONAL BUILDING CODE OF INDIA
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and 'accepted standards'
in the fulfillment of the requirements of the Code. The
latest version of a standard shall be adopted at the time
of enforcement of the Code. The standards listed may
be used by the Authority as a guide in conformance
with the requirements of the referred clauses in the Code.
(1)
IS No.
8888
(Part 1) : 1993
(2) 3792 : 1978
11907: 1986
(3) 13727 : 1993
Title
Guide for requirements of low
income housing: Part 1 Urban
area (first revision)
Guide for heat insulation of non-
industrial buildings {first revision)
Recommendations for calculation
of solar radiation on buildings
Guide for requirements of cluster
planning for housing
IS No.
(4)
12314 : 1987
(5)
4878 : 1986
(6)
4838 : 1990
(7) 4963 : 1987
(8) 14458
(Part 1) : 1998
(Part 2) : 1997
Title
Code of practice for sanitation
for leaching pits for rural
community
Byelaws for construction of
cinema buildings (first revision)
Anthropometric dimensions for
school children age group 5-17
years (second revision)
Recommendations for buildings
and facilities for the physically
challenged (first revision)
Guidelines for retaining walls
for hill area:
Selection of type of wall
Design of retaining/breast walls
PART 3 DEVELOPMENT CONTROL RULES AND GENERAL BUILDING REQUIREMENTS
63
NATIONAL BUILDING CODE OF INDIA
PART 4 FIRE AND LIFE SAFETY
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 FIRE PREVENTION
4 LIFE SAFETY
5 FIRE PROTECTION
6 ADDITIONAL OCCUPANCY- WISE REQUIREMENTS
ANNEX A CALORIFIC VALUES OF COMMON MATERIALS AND
TYPICAL VALUES OF FIRE LOAD DENSITY
ANNEX B BROAD CLASSIFICATION OF INDUSTRIAL AND
NON-INDUSTRIAL OCCUPANCIES INTO DIFFERENT
DEGREE OF HAZARD
ANNEX C FIRE PROTECTION REQUIREMENTS FOR HIGH RISE
BUILDINGS — 15 m IN HEIGHT OR ABOVE
ANNEX D FIRE PROTECTION CONSIDERATIONS FOR VENTING IN
INDUSTRIAL BUILDINGS
ANNEX E GUIDELINES FOR FIRE DRILL AND EVACUATION
PROCEDURES FOR HIGH RISE BUILDINGS
(ABOVE 15 m IN HEIGHT)
LIST OF STANDARDS
7
7
9
26
32
49
62
63
65
71
77
83
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
This Part of the Code deals with safety from fire. It specifies the demarcation of fire zones, restrictions on
construction of buildings in each fire zone, classification of buildings based on occupancy, types of building
construction according to fire resistance of the structural and non-structural components and other restrictions
and requirements necessary to minimize danger to life from fire, smoke, fumes or panic before the buildings can
be evacuated. The Code recognizes that safety of life is more than a matter of means of exits and accordingly
deals with various matters which are considered essential to the safety of life.
Fire protection techniques have to be based on the fire behaviour characteristics of different materials and structural
elements of buildings. The activities pursued by the occupants of buildings must also be taken into consideration
for assessing the extent of hazards, and method should then be devised by which the hazards could be minimized.
An indefinite combination of variables is involved in the phenomenon of fire, all of which cannot be quantified.
The requirements of this Code should, therefore, be taken as a guide and an engineering design approach should
be adopted for ensuring a fire safe design for buildings. It would also be necessary for this purpose to associate
qualified and trained fire protection engineers with the planning of buildings, so that adequate fire protection
measures could be incorporated in the building design right from the beginning.
Absolute safety from fire is not attainable in practice. The objective of this Part is to specify measures that will
provide that degree of safety from fire which can be reasonably achieved. The Code endeavours to avoid
requirements that might involve unreasonable hardships or unnecessary inconvenience or interference with normal
use and occupancy of buildings, but insists upon compliance with minimum standards for fire safety necessary in
public interest. For ensuring compliance of fire protection equipments/installations to the laid down quality
requirements, it is desirable to use such equipments/installation duly certified under the BIS Certification Marks
Scheme.
While providing guidelines for minimizing chances of occurrence of fire through passive fire protection measures,
this Part does not intend to cover all aspects of general fire prevention including sources of ignition. Nor does it
cover the prevention of accidental personal injuries during the course of normal occupancy of buildings.
This Part while recognizing that panic in a building on fire may be uncontrollable, deals with the potential panic
hazard through measures designed to prevent the development of panic. Experience indicates that panic seldom
develops even in the presence of potential danger, so long as occupants of buildings are moving towards exits
which they can see within a reasonable distance and with no obstruction or undue congestion in the path of
travel However, any uncertainty as to the location or adequacy of means of egress, the presence of smoke or
fumes and the stoppage of travel towards the exit, such as may occur when one person stumbles and falls on
stairs, may be conducive to panic. Danger from panic is greater when a large number of people are trapped in a
confined area.
Experience has shown that concealed spaces within a building, such as, space between ceiling and false ceiling,
horizontal and vertical ducts, etc, tend to act as flues/tunnels during a fire. Provision should, therefore, be made
to provide fire stopping within such spaces.
Nothing in this Part of the Code shall be construed to prohibit better types of building construction, more exits or
otherwise safer conditions than the minimum requirements specified in this Part.
Compliance with this Part shall not be construed as eliminating or reducing the necessity for other provisions for
safety of persons using a building or structure under normal occupancy conditions. Nor shall any provision of
this Code be construed as requiring or permitting any addition that may be hazardous under normal occupancy
conditions.
One of the major points brought out in this Part is the limitation of heights and areas of buildings based on fire
safety of the occupants. Individual municipal corporations are free to alter Table 19 based on local conditions,
PART 4 FIRE AND LIFE SAFETY 3
but the ratios of areas as maintained in the table for different occupancies and types of construction shall be
adhered to.
Advantage has been taken of the developments, particularly in fire resistance rating of materials, designating
types of construction in a rational manner and relating the area limitations of different occupancies to different
types of construction.
Halons (halogenated hydrocarbons) which exhibit exceptional fire fighting and explosion prevention/suppression
characteristics have been found to possess high ozone depleting potential. They come under Group II of Annex
A of the Montreal Protocol on Substances that Deplete the Ozone Layer, the international environmental agreement
for phasing out ozone depleting substances. Due to increasing evidence that the ozone layer is getting depleted at
a faster rate than thought earlier, the developed countries accelerated their phase-out schedule with a view to
achieving 100 percent phase-out of halons by 1 January 1994, instead of the earlier target date of 1 January 2000
after which only essential use of halon was allowed. For developing countries like India, the total phase-out of
halons is to be achieved by 1 January 2010, as per Montreal Protocol, unless a decision is taken in between to
hasten up the phase-out of ozone depleting substances. India, having become a signatory to the Protocol in June
1992, is committed to abide by the Montreal Protocol decisions. In accordance with Ministry of Environment
and Forests, Government of India, Ozone Depleting Substances (Regulations), Rules, 2000, the manufacture of
halon based fire extinguishers and extinguishing systems has been phased out by 1 January 2001. Meanwhile,
the practical implications of the phasing out of the halons cover, by and large, the following aspects:
a) Availability of halons will be restricted;
b) Non-standard halon extinguishers, like aerosol type, shall not be permitted;
c) Discharge of halons for training/testing, etc shall not be permitted;
d) All efforts shall be made for avoiding/minimizing halon emissions at various levels such as production,
fire equipment manufacture, use, service and maintenance;
e) Since 'drop-in' substitutes for halons are not likely to be available on a commercial scale in the near
future, wherever possible, instead of halon, use of suitable alternative extinguishing media/methods
will be resorted to, even accepting some trade-offs, if necessary; and
f) Halons shall be restricted for 'essential uses' only, for protection of critical fire explosion risk areas
which would otherwise result in serious impairment of an essential service to society, or pose an
unacceptable threat to life, the environment, or national security.
NOTE — Detailed instructions which will be issued by the Government of India from time-to-time for implementation of the
Country Programme for the phasing out of ozone depleting substance (ODS) and regarding permitting use of halons for
applications till the availability of proper substitutes, shall have to be complied with.
The first version of this Part was formulated in 1970 and first revision was brought out in 1983. Subsequently the
first revision of this Part was modified in 1997 through Amendment No. 3 to 1983 version of the Code. This
modified version of this part included few tables for the fire resistance ratings of various building components,
such as walls, columns, beams and floors. The requirements for wet riser, down-comer, automatic sprinkler
installation, high velocity (10-15 m/s) water spray or foam generating system, etc, for buildings were modified.
Annex giving guidelines for selection of fire detectors had been deleted and relevant Indian Standards on fire
alarm system and smoke detectors had been referred. Also, Annex for determination of fire loads and fire load
density for arriving at the classification of occupancy hazard and calorific values of some common materials
were included. Annex for broad classification of industrial and non-industrial occupancies into low, moderate
and high hazard had also been included.
As a result of implementation of this Part, some useful suggestions have emerged. This revision has, therefore,
been prepared to take care of the same. The significant modifications incorporated include:
a) The text has now been divided into the following broad clauses:
1) Fire Prevention — Covering aspects of fire prevention pertaining to design and construction of
buildings on passive fire protection measures, also describing the various types of building materials
and their fire rating.
2) Life Safety — Covering life safety provisions in the event of fire and similar emergencies, also
addressing construction and occupancy features that are necessary to minimize danger to life from
fire, smoke, fumes or panic.
NATIONAL BUILDING CODE OF INDIA
3) Fire Protection — covering the significant appurtenances and their related components and guidelines
for selecting the correct type of equipment and installation meant for fire protection of the building,
depending upon the classification and type of the building.
b) The classification of building based on occupancy has been elaborated, with:
1) Starred hotels now covered as a new sub-division A-6 under occupancy Group A Residential.
2) Heritage structures and archeological monuments now covered under sub-division D-3 occupancy
Group D Assembly buildings.
3) Mixed assembly occupancies now covered as a new sub-division D-6 and under ground elevated
railways have been covered as a new sub-division D-7 under occupancy Group D Assembly
buildings.
4) TV stations now covered under sub-division E-5 of occupancy Group E Business buildings.
c) The minimum capacity of smoke exhaust equipment has been increased to 12 air changes per hour.
d) For the external stairs for exit requirements, the width and treads have been increased to 1 250 mm and
250 mm respectively.
e) Under the requirements for institutional buildings the clear width of all required exits which serve as
egress from hospital or infirmary section has been increased from 1.5 m to 2 m. Also, provision of
patient-lift has been included.
f) Due cognizance of halon phase out programme has been taken, while specifying provisions in this Part
with respect to fire protection using fire extinguishers/systems.
All standards cross-referred to in the main text of this section, are subject to the revision. The parties to agreement
based on this Part are encouraged to investigate the possibility of applying the most recent editions of the
standards.
PART 4 FIRE AND LIFE SAFETY
NATIONAL BUILDING CODE OF INDIA
PART 4 FIRE AND LIFE SAFETY
1 SCOPE
This Part covers the requirements for fire prevention,
life safety in relation to fire and fire protection of
buildings. The Code specifies construction, occupancy
and protection features that are necessary to minimize
danger to life and property from fire.
2 TERMINOLOGY
2.0 For the purpose of this Part, the following
definitions shall apply.
2.1 Automatic Fire Detection and Alarm System
— Fire alarm system comprising components for
automatically detecting a fire, initiating an alarm of
fire and initiating other actions as appropriate.
NOTE — The system may also include manual fire alarm call
points.
2.2 Automatic Sprinkler System — A system of water
pipes fitted with sprinkler heads at suitable intervals and
heights and designed to actuate automatically, control
and extinguish a fire by the discharge of water.
2.3 Building — Any structure for whatsoever purpose
and of whatsoever materials constructed and every part
thereof whether used as human habitation or not and
includes foundation, plinth, walls, floors, roofs,
chimneys, plumbing and building services, fixed
platforms, VERANDAH, balcony, cornice or projection,
part of a building or anything affixed thereto or any wall
enclosing or intended to enclose any land or space
and signs and outdoor display structures. Tents,
SHAMIANAHS, tarpaulin shelters, etc, erected for
temporary and ceremonial occasions with the permission
of the Authority shall not be considered as building.
2.4 Building, Height of — The vertical distance
measured in the case of flat roofs, from the average level
of the ground around and contiguous to the building or
as decided by the Authority to the terrace of the last
livable floor of the building adjacent to the external wall;
and in the case of pitched roofs, up to the point where
the external surface of the outer wall intersects the
finished surface of the sloping roof; and in the case of
gables facing the road, the mid-point between the eaves
level and the ridge. Architectural features serving no
other function except that of decoration, shall be
excluded for the purpose of measuring heights.
2.5 Combustible Material — The material which
either burns itself or adds heat to a fire, when tested
for non-combustibility in accordance with accepted
standard [4(1)].
2.6 Covered Area — Ground area covered by the
building immediately above the plinth level. The area
covered by the following in the open spaces is excluded
from covered area (see Table 19):
a) garden, rockery, well and well structures,
plant nursery, waterpool, swimming pool (if
uncovered), platform round a tree, tank,
fountain, bench, CHABUTARA with open top
and unenclosed on sides by walls and the like;
b) drainage culvert, conduit, catch-pit, gully pit,
chamber, gutter and the like;
c) compound wall, gate, unstoreyed porch and
portico, slide, swing, uncovered staircases,
ramp areas covered by CHHAJJA and the like;
and
d) watchman's booth, pumphouse, garbage
shaft, electric cabin or sub-stations, and such
other utility structures meant for the services
of the building under consideration.
NOTE — For the purpose of this Part, covered area
equals the plot area minus the area due for open spaces
in the plot.
2.7 Down-comer — An arrangement of fire fighting
within the building by means of down-comer pipe
connected to terrace tank through terrace pump, gate
valve and non-return valve and having mains not less
than 100 mm internal diameter with landing valves on
each floor/landing. It is also fitted with inlet
connections at ground level for charging with water
by pumping from fire service appliances and air release
valve at roof level to release trapped air inside.
2.8 Dry Riser — An arrangement of fire fighting
within the building by means of vertical rising mains
not less than 100 mm internal diameter with landing
valves on each floor/landing which is normally dry
but is capable of being charged with water usually by
pumping from fire service appliances.
2.9 Emergency Lighting — Lighting provided for use
when the supply to the normal lighting fails.
2.10 Emergency Lighting System — A complete but
discrete emergency lighting installation from the
standby power source to the emergency lighting
lamp(s), for example, self-contained emergency
luminaire or a circuit from central battery generator
connected through wiring to several escape luminaries.
2.11 Escape Lighting — That part of emergency
lighting which is provided to ensure that the escape
route is illuminated at all material times, for example,
at all times when persons are on the premises, or at
times the main lighting is not available, either for the
whole building or for the escape routes.
PART 4 FIRE AND LIFE SAFETY
2.12 Fire Door — A fire-resistive door approved for
openings in fire separation.
2.13 Fire Exit — A way out leading to an escape route
having panic bar hardware provided on the door.
2.14 Fire Lift — The lift installed to enable fire
services personnel to reach different floors with
minimum delay, having such features as required in
accordance with this Part.
2.15 Fire Load — Calorific energy, of the whole
contents contained in a space, including the facings of
the walls, partitions, floors and ceilings.
2.16 Fire Load Density — Fire load divided by floor
area.
2.17 Fire Resistance Rating — The time that a
material or construction will withstand the standard
fire exposure as determined by fire test done in
accordance with the standard methods of fire tests of
materials/structures.
2.18 Fire Resistance — Fire resistance is a property
of an element of building construction and is the
measure of its ability to satisfy for a stated period some
or all of the following criteria:
a) resistance to collapse,
b) resistance to penetration of flame and hot
gases, and
c) resistance to temperature rise on the unexposed
face up to a maximum of 180°C and/or
average temperature of 150°C.
2.19 Fire Separation — The distance in metres
measured from the external wall of the building
concerned to the external wall of any other building
on the site, or from other site, or from the opposite
side of street or other public space for the purpose of
preventing the spread of fire.
2.20 Fire Separating Wall — The wall provides
complete separation of one building from another or
part of a building from another or part of a building
from another part of the same building to prevent any
communication of fire or heat transmission to wall itself
which may cause or assist in the combustion of
materials on the side opposite to that portion which
may be on fire.
2.21 Fire Stop — A fire resistant material, or
construction, having a fire resistance rating of not lesss
than the fire separating elements, installed in concealed
spaces or between structural elements of a building to
prevent the spread/propagation of fire and smoke through
walls, ceilings and like as per the laid down criteria.
2.22 Fire Tower — An enclosed staircase which can
only be approached from the various floors through
landings or lobbies separated from both the floor areas
and the staircase by fire-resisting doors, and open to
the outer air.
2.23 Fire Resisting Wall — A fire resistance rated
wall, having protected openings, which restricts the
spread of fire and extends continuously from the
foundation to at least 1 m above the roof.
2.24 Floor Area Ratio (FAR) — The quotient
obtained by dividing the total covered area (plinth area)
on all floors by the area of the plot:
FAR =
Total covered area of all floors
Plot area
2.25 High Rise Building — For the purpose of this
Part, all buildings 15 m or above in height shall be
considered as high rise buildings.
2.26 Horizontal Exit — An arrangement which
allows alternative egress from a floor area to another
floor at or near the same level in an adjoining building
or an adjoining part of the same building with adequate
fire separation.
2.27 Means of Egress — A continuous and
unobstructed way of travel from any point in a building
or structure to a place of comparative safety.
2.28 Occupancy or Use Group — The principal
occupancy for which a building or a part of a building
is used or intended to be used; for the purpose of
classification of a building according to the occupancy,
an occupancy shall be deemed to include subsidiary
occupancies which are contingent upon it.
2.29 Plinth Area — The built-up covered area measured
at the floor level of the basement or of any storey.
2.30 Pressurization — The establishment of a
pressure difference across a barrier to protect a
stairway, lobby, escape route or room of a building
from smoke penetration.
2.31 Pressurization Level — The pressure difference
between the pressurized space and the area served by
the pressurized escape route, expressed in pascals (Pa).
2.32 Roof Exits — A means of escape on to the roof
of a building, where the roof has access to it from the
ground. The exit shall have adequate cut-off within
the building from staircase below.
2.33 Site Plot — A parcel (piece) of land enclosed by
definite boundaries.
2.34 Stack Pressure — Pressure difference caused
by a temperature difference creating an air movement
within a duct, chimney or enclosure.
2.35 Travel Distance — The distance to be travelled
from any point in a building to a protected escape route,
external escape route or final exit.
8
NATIONAL BUILDING CODE OF INDIA
2.36 Ventilation — Supply of outside air into, or the
removal of inside air from an enclosed space.
2.37 Venting Fire — The process of inducing heat
and smoke to leave a building as quickly as possible
by such paths that lateral spread of fire and heat is
checked, fire fighting operations are facilitated and
minimum fire damage is caused.
2.38 Volume to Plot Area Ratio (VPR) — The ratio
of volume of building measured in cubic metres to the
area of the plot measured in square metres and
expressed in metres.
2.39 Wet Riser — An arrangement for fire fighting
within the building by means of vertical rising mains
not less than 100 mm nominal diameter with landing
valves on each floor/landing for fire fighting purposes
and permanently charged with water from a pressurized
supply.
NOTE — For definitions of other terms, reference shall be
made to good practice [4(2)].
3 FIRE PREVENTION
3.1 Classification of Building Based on Occupancy
3.1.1 General Classification
All buildings, whether existing or hereafter erected
shall be classified according to the use or the character
of occupancy in one of the following groups:
Group A Residential
Group B Educational
Group C Institutional
Group D Assembly
Group E Business
Group F Mercantile
Group G Industrial
Group H Storage
Group J Hazardous
3.1.1.1 Minor occupancy incidental to operations in
another type of occupancy shall be considered as part
of the main occupancy and shall be classified under
the relevant group for the main occupancy.
Examples of buildings in each group are given in 3.1.2
to 3.1.10.
3.1.2 Group A Residential Buildings
These shall include any building in which sleeping
accommodation is provided for normal residential
purposes with or without cooking or dining or both
facilities, except any building classified under Group C.
Buildings and structures under Group A shall be further
sub-divided as follows:
Sub-division A-l Lodging or rooming houses
Sub-division A-2 One or two-family private
dwellings
Sub-division A-3 Dormitories
Sub-division A-4 Apartment houses (flats)
Sub-division A-5 Hotels
Sub-division A-6 Hotels (Starred)
a) Sub-division A-l Lodging or rooming houses
— These shall include any building or group
of buildings under the same management, in
which separate sleeping accommodation for
a total of not more than 40 persons (beds), on
transient or permanent basis, with or without
dining facilities but without cooking facilities
for individuals is provided. This includes inns,
clubs, motels and guest houses.
A lodging or rooming house shall be classified
as a dwelling in sub-division A-2 if no room
in any of its private dwelling units is rented
to more than three persons.
b) Sub-division A-2 One or two-family private
dwellings — These shall include any private
dwelling which is occupied by members of
one or two families and has a total sleeping
accommodation for not more than 20 persons.
If rooms in a private dwelling are rented to
outsiders, these shall be for accommodating
not more than three persons per room.
If sleeping accommodation for more than 20
persons is provided in any one residential
building, it shall be classified as a building in
sub-division A-l, A-3 or A-4 as the case may
be.
c) Sub-division A-3 Dormitories — These shall
include any building in which group sleeping
accommodation is provided, with or without
dining facilities for persons who are not
members of the same family, in one room or
a series of closely associated rooms under
joint occupancy and single management, for
example, school and college dormitories,
students, and other hostels and military
barracks.
d) Sub-division A-4 Apartment houses (flats) —
These shall include any building or structure
in which living quarters are provided for three
or more families, living independently of each
other and with independent cooking facilities,
for example, apartment houses, mansions and
chawls.
e) Sub-division A-5 Hotels — These shall
include any building or group of buildings
under single management, in which sleeping
accommodation is provided, with or without
dining facilities for hotels classified up to
4 Star Category.
PART 4 FIRE AND LIFE SAFETY
f) Sub-division A-6 Hotels (starred) — These
shall include the hotels duly approved by the
concerned authorities as Five Star and above
Hotels.
3.1.3 Group B Educational Buildings
These shall include any building used for school,
college, other training institutions for day-care
purposes involving assembly for instruction, education
or recreation for not less than 20 students.
Buildings and structures under Group B shall be further
sub-divided as follows:
Sub-division B-l Schools up to senior secondary
level
Sub-division B-2 All others/training institutions
a) Sub-division B-l Schools up to senior
secondary level — This sub-division shall
include any building or a group of buildings
under single management which is used for
students not less than 20 in number.
b) Sub-division B-2 All others/training
institutions — This sub-division shall include
any building or a group of buildings under
single management which is used for students
not less than 100 in number.
In the case of temporary buildings/structures which
are utilized for educational purposes, the provisions
of 3.2.5.3 shall apply.
If residential accommodation is provided in the
schools/institutions, that portion of occupancy shall be
classified as a building in sub-division A-3.
3.1.4 Group C Institutional Buildings
These shall include any building or part thereof, which
is used for purposes, such as medical or other treatment
or care of persons suffering from physical or
mental illness, disease or infirmity; care of infants,
convalescents or aged persons and for penal or
correctional detention in which the liberty of the
inmates is restricted. Institutional buildings ordinarily
provide sleeping accommodation for the occupants.
Buildings and structures under Group C shall be further
sub-divided as follows:
Sub-division C-l Hospitals and sanatoria
Sub-division C-2 Custodial institutions
Sub-division C-3 Penal and mental institutions
a) Sub-division C-l Hospitals and sanatoria —
This sub-division shall include any building or
a group of buildings under single management,
which is used for housing persons suffering
from physical limitations because of health
or age, for example, hospitals, infirmaries,
sanatoria and nursing homes.
b) Sub-division C-2 Custodial institutions —
This sub-division shall include any building
or a group of buildings under single
management, which is used for the custody
and care of persons, such as children,
convalescents and the aged, for example,
homes for the aged and infirm, convalescent
homes and orphanages.
c) Sub-division C-3 Penal and mental institutions
— This sub-division shall include any
building or a group of buildings under single
management, which is used for housing
persons under restraint, or who are detained
for penal or corrective purposes, in which the
liberty of the inmates is restricted, for
example, jails, prisons, mental hospitals,
mental sanatoria and reformatories.
3.1.5 Group D Assembly Buildings
These shall include any building or part of a building,
where number of persons not less than 50 congregate
or gather for amusement, recreation, social, religious,
patriotic, civil, travel and similar purposes, for
example, theatres, motion picture houses, assembly
halls, auditoria, exhibition halls, museums, skating
rinks, gymnasiums, restaurants, places of worship, dance
halls, club rooms, passenger stations and terminals of
air, surface and marine public transportation services,
recreation piers and stadia, etc.
Buildings under Group D shall be further sub-divided
as follows:
Sub-division D-l Buildings having a theatrical or
motion picture or any other stage and fixed seats
for over 1 000 persons
Sub-division D-2 Buildings having a theatrical or
motion picture or any other stage and fixed seats
upto 1 000 persons
Sub-division D-3 Buildings without a permanent
stage having accommodation for 300 or more
persons but no permanent seating arrangement.
Sub-division D-4 Buildings without a permanent
stage having accommodation for less than 300
persons with no permanent seating arrangement.
Sub-division D-5 All other structures including
temporary structures designed for assembly of
people not covered by sub-divisions D-l to D-4,
at ground level.
Sub-division D-6 Buildings having mixed
occupancies providing facilities such as shopping,
cinema theatres, and restaurants.
Sub-division D-7 All other structures, elevated or
underground, for assembly of people not covered
by sub-divisions D-l to D-6.
a) Sub-division D-l — This sub-division shall
10
NATIONAL BUILDING CODE OF INDIA
include any building primarily meant for
theatrical or operatic performances and
exhibitions and which has a raised stage,
proscenium curtain, fixed or portable scenery
or scenery loft, lights, motion picture houses,
mechanical appliances or other theatrical
accessories and equipment and which is
provided with fixed seats for over 1 000 persons.
b) Sub-division D-2 — This sub-division shall
include any building primarily meant for use
as described for sub-division D-l, but with
fixed seats up to 1 000 persons.
c) Sub-division D-3 — This sub-division shall
include any building, its lobbies, rooms and
other spaces connected thereto, primarily
intended for assembly of people, but which
has no theatrical stage or permanent theatrical
and/or cinematographic accessories and has
accommodation for 300 persons or more, for
example, dance halls, night clubs, halls for
incidental picture shows, dramatic, theatrical
or educational presentation, lectures or other
similar purposes having no theatrical stage
except a raised platform and used without
permanent seating arrangement; art galleries
exhibition halls, community halls, marriage
halls, places of worship, museums, lecture
halls, passenger terminals and Heritage and
Archeological Monuments.
d) Sub-division D-4 — This sub-division shall
include any building primarily intended for
use as described in sub-division D-3, but with
accommodation for less than 300 persons with
no permanent seating arrangements.
e) Sub-division D-5 — This sub-division shall
include any building or structure permanent
or temporary meant for assembly of people not
covered by sub-divisions D-l to D-4, for
example, grandstands, stadia, amusement park
structures, reviewing stands and circus tents.
f) Sub-division D-6 — This sub-division shall
include any building for assembly of people
provided with multiple services/facilities like
shopping, cinema theatres and restaurants, for
example, multiplexes.
g) Sub-division D-7 — This sub-division shall
include any building or structure permanent
or temporary meant for assembly of people
not covered by D-l to D-6, for example,
underground or elevated railways.
3.1.6 Group E Business Buildings
These shall include any building or part of a building
which is used for transaction of business (other than
that covered by Group F and part of buildings covered
by 3.1.1.1); for keeping of accounts and records and
similar purposes, professional establishments, service
facilities, etc. City halls, town halls, court houses and
libraries shall be classified in this group so far as the
principal function of these is transaction of public
business and keeping of books and records.
Business buildings shall be further sub-divided as
follows:
Sub-division E-l Offices, banks, professional
establishments, like offices of architects,
engineers,: doctors, lawyers and police stations.
Sub-division E-2 Laboratories, research
establishments, libraries and test houses.
Sub-division E-3 Computer installations.
Sub-division E-4 Telephone exchanges.
Sub-division E-5 Broadcasting stations and T.V.
stations.
3.1.7 Group F Mercantile Buildings
These shall include any building or part of a building,
which is used as shops, stores, market, for display and
sale of merchandise, either wholesale or retail.
Mercantile buildings shall be further sub-divided as
follows:
Sub-division F-l Shops, stores, departmental
stores markets with area up to 500 m 2 .
Sub-division F-2 Shops, stores, departmental
stores markets with area more than 500 m 2 .
Sub-division F-3 Underground shopping centres.
Storage and service facilities incidental to the sale
of merchandise and located in the same building
shall be included under this group.
3.1.8 Group G Industrial Buildings
These shall include any building or part of a building
or structure, in which products or materials of all kinds
and properties are fabricated, assembled, manufactured
or processed, for example, assembly plants, industrial
laboratories, dry cleaning plants, power plants,
generating units, pumping stations, fumigation
chambers, laundries, buildings or structures in gas
plants, refineries, dairies and saw-mills, etc.
Buildings under Group G shall be further sub-divided
as follows:
Sub-division G-l Buildings used for low hazard
industries.
Sub-division G-2 Buildings used for moderate
hazard industries.
Sub-division G-3 Buildings used for high hazard
industries.
The hazard of occupancy, for the purpose of the Code,
shall be the relative danger of the start and spread of
PART 4 FIRE AND LIFE SAFETY
11
fire, the danger of smoke or gases generated, the danger
of explosion or other occurrences potentially
endangering the lives and safety of the occupants of
the buildings.
Hazard of occupancy shall be determined by the
Authority on the basis of the fire loads of the contents,
and the processes or operations conducted in
the building, provided, however, that where the
combustibility of the material, the flame spread rating
of the interior finish or other features of the building
or structure are such as to involve a hazard greater than
the occupancy hazard, the greater degree of hazard shall
govern the classification.
For determination of fire loads and fire load density
for arriving at the classification of occupancy hazard,
guidance including the calorific values of some
common materials, is given at Annex A.
A broad classification of industrial and non-industrial
occupancies into low, moderate and high hazard classes
is given at Annex B, for guidance. Any occupancy not
covered in Annex B, shall be classified in the most
appropriate class depending on the degree of hazard.
Where different degrees of hazard of occupancy exist
in different parts of a building, the most hazardous of
those shall govern the classification for the purpose of
this Code, except in cases where hazardous areas are
segregated or protected as specified in the Code.
a) Sub-division G-l — This sub-division shall
include any building in which the contents are
of such comparative low combustibility and the
industrial processes or operations conducted
therein are of such a nature that there are hardly
any possibilities for any self propagating fire to
occur and the only consequent danger to life
and property may arise from panic, fumes or
smoke, or fire from some external source.
b) Sub-division G-2 — This sub-division shall
include any building in which the contents or
industrial processes or operations conducted
therein are liable to give rise to a fire which
will burn with moderate rapidity or result in
other hazardous situation and may give off a
considerable volume of smoke, but from
which neither toxic fumes nor explosions are
to be feared in the event of fire.
c) Sub-division G-3 — This sub-division shall
include any building in which the contents or
industrial processes or operations conducted
therein are liable to give rise to a fire which
will burn with extreme rapidity or result in
other hazardous situation or from which
poisonous fumes or explosions are to be
feared in the event of a fire. For fire safety in
petroleum and fertilizer plant, good practice
[4(3)] may be referred.
3.1.9 Group H Storage Buildings
These shall include any building or part of a building
used primarily for the storage or sheltering (including
servicing, processing or repairs incidental to storage)
of goods, ware or merchandise (except those that
involve highly combustible or explosive products
or materials) vehicles or animals, for example,
warehouses, cold storage, freight depots, transit sheds,
storehouses, truck and marine terminals, garages,
hangers, grain elevators, barns and stables. Storage
properties are characterized by the presence of
relatively small number of persons in proportion to
the area. Any new use which increase the number of
occupants to a figure comparable with other classes of
occupancy shall change the classification of the
building to that of the new use, for example, hangars
used for assembly purposes, warehouses used for office
purposes, garage buildings used for manufacturing.
3.1.10 Group J Hazardous Buildings
These shall include any building or part of a building
which is used for the storage, handling, manufacture
or processing of highly combustible or explosive
materials or products which are liable to burn with
extreme rapidity and or which may produce poisonous
fumes or explosions for storage, handling,
manufacturing or processing which involve highly
corrosive, toxic or noxious alkalis, acids or other liquids
or chemicals producing flame, fumes and explosive,
poisonous, irritant or corrosive gases; and for the
storage, handling or processing of any material
producing explosive mixtures of dust which result in
the division of matter into fine particles subject to
spontaneous ignition. Examples of buildings in this
class are those buildings which are used for:
a) Storage, under pressure of more than
0.1 N/mm 2 and in quantities exceeding 70 m 3 ,
of acetylene, hydrogen, illuminating and
natural gases, ammonia, chlorine, phosgene,
sulphur dioxide, carbon dioxide, methyloxide
and all gases subject to explosion, fume or
toxic hazard, cryogenic gases, etc;
b) Storage and handling of hazardous and highly
flammable liquids, liquefiable gases like LPG,
rocket propellaflts, etc;
c) Storage and handling of hazardous and highly
flammable or explosive materials (other than
liquids); and
d) Manufacture of artificial flowers, synthetic
leather, ammunition, explosives and fireworks.
NOTE — A list of hazardous substances giving
quantities, for which or exceeding which owners
handling such substances are required to be covered
under the Public Liability Insurance Act, has been
notified under Government of India, Ministry of
Environment and Forests Notification No. G.S.R.
347(E) dated 1 August 1996.
12
NATIONAL BUILDING CODE OF INDIA
3.1.11 Any building not covered by Annex B or 3.1.8
shall be classified in the group which most nearly
resembles its existing or proposed use.
3.1.12 Where change in the occupancy of any building
places it in a different group or in a different sub-
division of the same group, such building shall be made
to comply with the requirements of the Code for the
new group or its sub-division.
3.1.13 Where the new occupancy of a building is less
hazardous, based on life and fire risk, than its existing
occupancy, it shall not be necessary to conform to the
requirements of the Code for the new group or its sub-
division.
3.1.14 A certificate of occupancy shall be necessary, as
required under Part 2 4 Administration' , before any change
is effected in the character of occupancy of any building.
3.2 Fire Zones
3.2.1 Demarcation
The city or area under the jurisdiction of the Authority
shall for the purpose of the Code, be demarcated into
distinct zones, based on fire hazard inherent in the
buildings and structures according to occupancy
(see 3.1), which shall be called as Tire Zones'.
3.2.2 Number and Designation of Fire Zones
3.2.2.1 The number of fire zones in a city or area under
the jurisdiction of the Authority depends upon the
existing layout, types of building construction (see 3.3),
classification of existing buildings based on occupancy
(see 3.1) and expected future development of the city
or area. In large cities or areas, three fire zones may be
necessary, while in smaller ones, one or two may be
adequate.
3.2.2.2 The fire zones shall be made use of in land use
development plan and shall be designated as follows:
a) Fire Zone No. 1 — This shall comprise areas
having residential (Group A), educational
(Group B), institutional (Group C), and
assembly (Group D), small business (Sub-
divisions E- 1 ) and retail mercantile (Group F)
buildings, or areas which are under development
for such occupancies.
b) Fire Zone No. 2 — This shall comprise
business (Sub-divisions E-2 to E-5) and
industrial buildings (Sub-division G-l and
G-2), except high hazard industrial buildings
(Sub-division G-3) or areas which are under
development for such occupancies.
c) Fire Zone No. 3 — This shall comprise areas
having high hazard industrial buildings (Sub-
division G-3), storage buildings (Group H)
and buildings for hazardous used (Group J)
or areas which are under development for
such occupancies.
3.2.3 Change in the Fire Zone Boundaries
When the boundaries of any fire zone are changed, or
when it is intended to include other areas or types of
occupancies in any fire zone, it shall be done by
following the same procedure as for promulgating new
rules or ordinances or both.
3.2.4 Overlapping Fire Zones
3.2.4.1 When any building is so situated that it extends
to more than one fire zone, it shall be deemed to be in
the fire zone in which the major portion of the building
or structure is situated.
3.2.4.2 When any building is so situated that it extends
equally to more than one fire zone, it shall be deemed
to be in the fire zone having more hazardous occupancy
buildings.
3.2.5 Temporary Buildings or Structures
3.2.5.1 Temporary buildings and structures shall be
permitted only in Fire Zones No. 1 and 2 as the case
may be, according to the purpose for which these are
to be used, by special permit from the Authority for a
limited period and subject to such conditions as may
be imposed in the permit.
3.2.5.2 Such buildings and temporary structures shall
be completely removed on the expiry of the period
specified in the permit.
3.2.5.3 Adequate fire precautionary measures in the
construction of temporary structures and PANDALS
shall be taken in accordance with good practice [4(4)].
3.2.6 Restrictions on the Type of Construction for New
Buildings
3.2.6.1 Buildings erected in Fire Zone No. 1 shall
conform to construction of Type 1, 2, 3 or 4.
3.2.6.2 Buildings erected in Fire Zone No. 2 shall
conform to construction of Type 1, 2 or 3.
3.2.6.3 Buildings erected in Fire Zone No. 3 shall
conform to construction of Type 1 or 2.
3.2.7 Restrictions on Existing Buildings
The existing buildings in any fire zone shall not be
required to comply with the requirement of the Code
unless these are altered, or in the opinion of the
Authority, such building constitutes a hazard to the
safety of the adjacent property or the occupants of the
building itself or is an unsafe building. In the event of
alteration, it shall be necessary to obtain permission
of the Authority for such alteration consistent with fire
hazard (see Part 2 'Administration').
Alterations/modifications/renovations shall be
accomplished so as to ensure conformity with all the
PART 4 FIRE AND LIFE SAFETY
13
safety requirements of the new buildings. Such
alterations shall not in anyway bring down level of
fire and life safety below that which existed earlier.
Any addition or alterations or construction of cubicles
or partitioning for floor area exceeding 500 m 2 for all
high rise buildings shall be with approval of local fire
authority.
3.3 Types of Construction
3.3.1 General
The design of any building and the type of materials
used in its construction are important factors in making
the building resistant to a complete burn-out and in
preventing the rapid spread of fire, smoke or fumes,
which may otherwise contribute to the loss of lives
and property.
The fire resistance of a building or its structural and
non-structural elements is expressed in hours against
a specified fire load which is expressed in kcal/m 2 , and
against a certain intensity of fire. The fire-resistance
test for structural element shall be done in accordance
with good practice [4(5)]. For the purpose of the Code,
the types of construction according to fire resistance
shall be classified into four categories, namely,
Type 1 Construction, Type 2 Construction, Type 3
Construction and Type 4 'Construction'. The fire
resistance ratings for various types of construction for
structural and non-structural members shall be as given
in Table 1 .
For buildings 15 m in height or above non-combustible
materials should be us^ed for construction and the
internal walls of staircase enclosures should be of
brick work or reinforced concrete or any other
material of construction with minimum of 2 h rating.
The walls for the chimney shall be of Type 1 and
Type 2 Construction depending on whether the gas
temperature is above 200°C or less.
33.2 It is required that an element/component shall
have the requisite fire resistance rating when tested in
accordance with the accepted standard [4(1)].
Tables 2 to 18 provide available data regarding fire
resistance ratings of various building components such
as walls, columns, beams and floors. Fire damage
assessment, post fire structural safety assessment of
various structural elements of the building and
adequacy of the structural repairs can be done by the
fire resistance ratings mentioned in Tables 2 to 18.
Table 1 Fire Resistance Ratings of Structural and Non-Structural Elements (Hours)
(Clause 3.3.1)
lent Type of Construction
SI
Structural
No.
(1)
(2)
i)
Exterior walls:
a) Fire separation less than 3.7 m
a)
Bearing
b)
Non-bearing
b) Fire separation of 3.7 m or more
a)
Bearing
but less than 9 m
b)
Non-bearing
c) Fire separation of 9 m or more
a)
Bearing
b)
Non-bearing
ii)
iii)
iv)
v)
vi)
vii)
viii)
ix)
x)
xi)
xii)
Fire resisting walls
Fire separation assemblies (like fire
check doors)
Fire enclosures of exitways, hallways
and stairways
Shaft other than exitways, elevator
and hoistways
Exitway access corridors
Vertical separation of tenant spaces
Dwelling unit separation
Non-load bearing partitions
Interior bearing walls, bearing
partitions, columns, girders, trusses
(other than roof trusses) and framing
Structural members support walls
Floor construction including walls
Roof construction
Typel
Type 2
Type3
Type 4
(3)
(4)
(5)
(6)
4
2
2
2
\Vi
1
4
2
2
Wi
1
1
4
2
2
1
1
1
4
2
2
2
4
2
2
2
a) Supporting more than one floor
b) Supporting one floor only
c) Supporting a roof only
a) 5 m or less in height to lowest member
b) More than 5 m but less than 6.7 m in
height to lowest member
c) 6.7 m or more in height to lowest
member
1
/' 1
1
1
1
1
1
1
1
1
1
1
— At least half
an hour —
4
2
2
2
3
1*4
1
1
3
Vh
1
1
3
\Vi
1
1
3
\Yi
1
1
2
Vh
1
1
1
1
1
1
14
NATIONAL BUILDING CODE OF INDIA
Table 2 Masonry Walls: Solid (Required to Resist Fire from One Side at a Time)
(Clause 3.3.2)
SI Nature of Construction
Minimum Thickness (mm
), Excluding any
Finish for
a
No. and Materials
Fire Resistance (Hours) of
^-*
Load Bearing
Non-load Bearing
--*-
*
<*-*"
~"N
' —N
1
V/2
2
3
4
1
Vh
2
3
4
(1) (2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
i) Reinforced^ cement concrete
120
(25) 2)
140
(25) 2)
160
(25) 2)
200
(25) 2)
240
(25) 2)
ii) Unreinforced cement concrete
150
175
—
—
—
iii) No-fines concrete with :
a) 13 mm cement/sand or gypsum/sand
150
150
150
150
150
b) 13 mm light weight aggregate gypsum
150
150
150
150
150
plaster
iv) Bricks of clay:
a) Without finish
90
100
100
170
170
75
90
100
170
170
b) With 13 mm lightweight aggregate
90
90
90
100
100
75
90
90
90
100
gypsum plaster
v) Bricks of sand lime:
a) Without finish
90
100
100
190
190
75
90
, 100
170
170
b) With 13 mm lightweight aggregate
90
90
90
100
100
75
90
90
90
100
gypsum plaster
vi) Blocks of concrete:
a) Without finish
90
100
100
—
—
75
90
100
140
150
b) With 13 mm lightweight aggregate
90
90
90
100
100
75
75
75
90
100
gypsum plaster
c) With 13 mm cement/sand or gypsum/
75
90
90
100
140
sand
vii) Blocks of lightweight concrete:
a) Without finish
90
100
100
140
150
75
75
75
125
140
b) With 13 mm lightweight aggregate
90
90
90
100
100
50
63
75
75
75
gypsum plaster
c) With 13 mm cement/sand or gypsum/
75
75
75
90
100
sand
viii) Blocks of aerated concrete:
a) Without finish
90
100
100
140
180
50
63
63
75
100
b) With 13 mm lightweight aggregate
90
90
100
100
150
gypsum plaster
forceme
:nt.
Walls containing at least 1 percent of vertical rein
2) Minimum thickness of actual cover to reinforcement.
Table 3 Masonry Walls: Hollow (Required to Resist Fire from One Side at a Time)
(Clause 3.3.2)
SI
Nature of Construction
]
Minimum Thickness (mm), Excluding any Finish for a
i
No.
and Materials
Fire Resistance (Hours) of
•j..
*^
Load Bearing
fJon-load
Bering
~~ "*"**.
-*-,
1
Wi
2
3
4
Vi
1
\V2
2
3
4
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(ID
(12)
(13)
i)
Bricks of clay:
■'
a)
Without finish
170
170
170
200
200
75
75
90
100
170~
* 170
b)
With 13 mm
gypsum plaster
lightweight
aggregate
100
100
170
170
170
75
75
90
90
90
100
ii)
Blocks of concrete:
a)
Without finish
90
125
125
140
140
150
b)
With 13 mm cement/sand or gypsum/sand
190
200
200
—
—
90
125
125
140
140
140
c)
With 13 mm
gypsum plaster
lightweight
aggregate
75
90
90
100
125
125
iii)
Blocks of lightweight
t concrete:
a)
Without finish
100
100
100
—
—
75
90
90
100
140
150
b)
With 13 mm cement/sand or gypsum/sand
75
75
75
100
140
140
c)
With 13 mm
gypsum plaster
lightweight
aggregate
"
63
63
63
75
90
100
PART 4 FIRE AND LIFE SAFETY
15
Table 4 Framed Construction, Load Bearing (Required to Resist Fire
from One Side at a Time)
(Clause 3.3.2)
SI Nature of Construction and Materials/Timber Studs at Centres not Minimum Thickness (mm) of Protection
No. Exceeding 600 mm, Faced on Each Side with for a Fire Resistance of lh
(1) (2) (3) '
i) Plasterboard layers with joints staggered, joints in outer layer taped and filled — Total 25
thickness for each face
ii) One layer of 12.7 mm plasterboard with a finish of lightweight aggregate gypsum 13
plaster
iii) Metal lath and plaster, thickness of plaster:
a) Sanded gypsum plaster (metal lathing grade) 22
b) Lightweight aggregate gypsum plaster 13
Table 5 Framed Construction, Non-Load Bearing (Required to Resist Fire
from One Side at a Time)
(Clause 3.3.2)
Nature of Construction and Materials/Steel or Timber Frame at Stud Minimum Thickness (mm) of Protection
Centres not Exceeding 600 mm, Facings on Both Sides of Construction for a Fire Resistance
Vih lh lVih 2h
0) (2) (3) (4) (5) (6)
A) Dry lining with materials fixed direct to studs
(without plaster finish)
1 . One layer of plasterboard with taped and filled joints Timber or steel 1 2.7
2. Two layers of plasterboard with joints staggered, joints in Timber or steel 19 25
outer layer taped and filled — Total thickness for each face
3. One layer of asbestos insulating board with transverse joints Timber or steel 9 12
backed by fillers of asbestos insulating board not less than 9
mm thick, or by timber
4. One layer of wood wool slabs Timber 25
5 . One layer of chipboard or of plywood Timber or steel 1 8
B) Lining with materials fixed direct to suds, with plaster finish:
Plasterboard of thickness: Timber or steel
a) With not less than 5 mm gypsum plaster finish 9.5
b) With not less than 13 mm gypsum plaster finish 12.7
C) Wet finish:
Metal lath and plaster, thickness of plaster:
a) Sanded gypsum plaster Timber or steel 1 3
b) Lightweight aggregate gypsum plaster Timber
Steel
Table 6 Framed External Walls Load Bearing (Required to Resist Fire
from One Side at a Time)
(Clause 3.3.2)
13 19 25
13
SI
No.
Nature of Construction and Materials Minimum Thickness (mm) of Protection
for a Fire Resistance of 1 h
(1)
(2) (3)
Timber studs at centers not exceeding 600 mm with internal linings of :
i)
Plasterboard layers with joints in outer layer taped and filled, total thickness of 25
plasterboard
16 NATIONAL BUILDING CODE OF INDIA
Table 7 Framed External Walls Non-Load Bearing Required to Resist Fire only
from Inside the Building (A)
(Clause 3.3.2)
Nature of Construction and Materials
Minimum Thickness (mm) of Protection for a
Fire Resistance
(1)
Vih
(2)
lh
(3)
(4)
Steel frame with an external cladding of non-combustible sheets (excluding
sheet steel), with a steel supporting framework and internal lining of:
1 . Metal lath and plaster, thickness of plaster:
a) Sanded gypsum plaster (metal lathing grade)
b) Lightweight aggregate gypsum plaster
2. Two layer of plasterboard with joints staggered joints in outer layer
taped and filled — Total thickness
3. Plasterboard of thickness:
a) With not less than 5 mm gypsum plaster finish
b) With not less than 13 mm gypsum plaster finish
c) With not less than 10 mm lightweight aggregate gypsum plaster
4. One layer of asbestos insulating board with transverse joints backed by
fillers of asbestos insulating board not less than 9 mm thick, or by timber
5. One layer of wood/wool slabs without finish
6. One layer of compressed straw building slabs:
a) Without finish
b) With not less than 5 mm gypsum plaster finish
7. Aerated concrete blocks
8. Bricks of clay:
2h
(5)
3h
(6)
4h
(7)
Without finish
With not less than 13 mm lightweight aggregate gypsum plaster
13
13
10
13
15
15
15
19
21
32
12.7
9.5
9.5
9
9
50
12
12
12
12
50
50
50
50
63
63
75
100
75 r
75
90
90
100
100
75
75
90
90
Table 8 Framed External Walls Non-Load Bearing Required to Resist Fire only
from Inside the Building (B)
(Clause 3.3.2)
Nature of Construction and Materials
(1)
Minimum Thickness (mm) of Protection to
Provide Sufficient Insulation to Achieve a
Modified Fire Resistance of Up to 4 h
(2)
Steel frame with an external cladding of sheet steel fully lapped, steel bolted and
fixed to steel sheeting rails, with timber or steel supporting framework and internal
lining of:
1 . Metal lath and plaster, thickness of plaster:
a) Sanded gypsum plaster (metal lathing grade) 13
b) Lightweight aggregate gypsum plaster 10
2. One layer of plasterboard with joints taped and filled 12.7
3. Plasterboard of thickness with not less than 5 mm gypsum plaster finish 9.5
4. One layer of asbestos insulating board with transverse joints backed by 9
fillers of asbestos insulating board not less than 9 mm thick, or by timber
5. One layer of wood/wool slabs 25
6. One layer of compressed straw building slabs 50
7. One layer of chipboard or of plywood 18
8. Aerated concrete blocks 50
9. Bricks of clay 75
10. Any internal decorative lining with a cavity fill independently supported 50
and retained in position of mineral fibre insulating material (excluding
glass) at a density of 48 kg/m 3
PART 4 FIRE AND LIFE SAFETY
17
Table 9 Framed Walls Non-Load Bearing Required to Resist Fire only from Inside the Building (C)
{Clause 3.3.2)
Nature of Construction and Materials
(1)
Minimum Thickness (mm) of Protection for a
Fire Resistance of IV2 h
(2)
Timber frame with external cladding of weather boarding or external plywood,
9.5 mm with an internal lining of:
1. Plasterboard not less than 9.5 mm thick, finished with:
a) Gypsum plaster
b) Lightweight aggregate gypsum plaster
2. Plasterboard not less than 12.7 mm thick, finished with:
a) Gypsum plaster
b) Lightweight aggregate gypsum plaster
3. One layer of asbestos insulating board with transverse joints backed by fillers
of asbestos insulating board not less than 9 mm thick, or by timber
13
10
10
10
9
12
Table 10 Reinforced Concrete Columns
(Clause 3.3.2)
SI
Nature of Construction and Materials
Minimum Dimensions (mm) Excluding
any finish,
No.
for a Hre Resistance of
Vih
lh
lVzh
2h
3h
4h
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
i)
Fully exposed
Width
150
200
250
300
400
450
Cover
40
40
40
40
40
40
ii)
50 percent exposed
Width
125
160
200
200
300
350
Cover
40
40
40
40
40
40
iii)
One face exposed
Thickness
100
120
140
160
200
240
Cover
40
40
40
40
40
40
Table 11 Concrete Beams
(Clause 3.3.2)
SI Nature of Construction and Materials
No.
Minimum Danensions (mm) Excluding any Finish,
for a Fire Resistance of
(1)
(2)
Vih
lh
l^h
2h
3h
4h
(3)
(4)
(5)
(6)
(7)
(8)
Width
200
200
200
200
240
280
Cover
20
20
20
40
60^
70^
Width
200
200
200
200
240
280
Cover
20
20
20
30
40
50 l)
Width
100
120
150
200
240
280
Cover
25
40
55
70
80
90
Width
80
100
120
150
200
240
Cover
20
30
40
55
70
80
i) Reinforced concrete (simply supported)
ii) Reinforced concrete (continuous)
iii) Prestressed concrete (simply supported)
iv) Prestressed concrete (continuous)
1 Require attention to the additional measures necessary to reduce the risk of spalling.
Table 12 Concrete Floors
(Clause 3.3.2)
SI
No.
(1)
Nature of Construction and Materials
(2)
Minimum Dimensions (mm) Excluding any Finish,
for a fire Resistance of
^— ■
— *
Vih
lh
IVih
2h
3h
4h
(3)
(4)
(5)
(6)
(7)
(8)
Thickness
75
95
110
125
150
170
Cover
20
20
25
35
45'>
55 1}
Thickness
75
95
110
125
150
170
Cover
20
20
20
25
35
45°
i) Reinforced concrete (simply supported)
ii) Reinforced concrete (continuous)
n Require attention to the additional measures necessary to reduce the risk of spalling.
18
NATIONAL BUILDING CODE OF INDIA
Table 13 Concrete Floors: Ribbed Open Soffit
(Clause 3.3.2)
SI
No.
(1)
Nature of Construction and Materials
(2)
Minimum Dimensions (mm) Excluding any Finish,
for a Fire Resistance of
Vi h
lh
lV4h
2h
3h
4h
(3)
(4)
(5)
(6)
(7)
(8)
Thickness of floor
75
95
110
125
150
170
Rib width
125
125
125
125
150
175
Cover
20
20
35
45
55
65
Thickness
75
95
110
125
150
170
Width
125
125
125
125
150
175
Cover
20
20
20
35
45
55
i) Reinforced concrete (simply supported)
ii) Reinforced concrete (continuous)
Table 14 Encased Steel Columns, 203 mm x 203 mm
(Protection Applied on Four Sides)
(Clause 3.3.2)
Nature of Construction and Materials
Minimum Dimensions (mm) Excluding any Finish,
for a Fire Resistance of
(1)
lh
(2)
A) Hollow protection (without an air cavity over the flanges):
1 . 1} Metal lathing with trowelled lightweight aggregate gypsum plaster
2. Plasterboard with 1.6 mm wire binding at 100 mm pitch, finished with
lightweight aggregate gypsum plaster not less than the thickness
specified:
a) 9.5 mm plaster board
b) 1 9 mm plaster board
3. Asbestos insulating boards, thickness of board:
a) Single thickness of board, with 6 mm cover fillets at transverse
joints
b) Two layers, of total thickness
4. Solid bricks of clay, composition or sand lime, reinforced in every
horizontal joint, unplastered
5. Aerated concrete blocks
6. Solid blocks of lightweight concrete hollow protection (with an air
cavity over the flanges)
B) Asbestos insulating board screwed to 25 mm asbestos battens
C) Solid protections
1. Concrete, not leaner than 1:2:4 mix (unplastered):
a) Concrete not assumed to be load bearing, reinforced 2)
b) Concrete assumed to be load bearing
2. Lightweight concrete, not leaner than 1:2:4 mix (unplastered): concrete
not assumed to be load bearing, reinforced 2)
13
10
12
lHh
(3)
2h
(4)
15
15
19
19
20
10
25
3h
(5)
32
13
4h
(6)
20
38
50
50
50
50
75
100
60
60
60
50
50
50
60
75
25
25
25
50
75
50
50
50
75
75
25
25
25
40
60
So fixed or designed, as to allow full penetration for mechanical bond.
2) Reinforcement shall consist of steel binding wire not less than 2.3 mm in thickness, or a steel mesh weighing not less than 0,5 kg/m . In
concrete protection, the spacing of that reinforcement shall not exceed 200 mm in any direction.
PART 4 FIRE AND LIFE SAFETY
19
Table 15 Encased Steel Beams, 406 mm x 176 mm (Protection Applied on Three Sides)
(Clause 3.3.2)
Nature of Construction and Materials Minimum Thickness (mm) of Protection for a
Fire Resistance of
Vih lh Wih 2h 3h 4h
0) (2) (3) (4) (5) (6) (7)
A) Hollow protection (without an air cavity beneath the lower flange):
1. ]> Metal lathing with trowelled lightweight aggregate gypsum plaster 13 13 15 20 25
2. Plasterboard with 1.6 mm wire binding 2) at 100 mm pitch, finished
with lightweight aggregate gypsum plaster not less than the
thickness specified:
a) 9.5 mm plaster board 10 10 15
b) 19 mm plaster board 10 10 13 20
3. Asbestos insulating boards, thickness of board:
a) Single thickness of board, with 6 mm cover fillets at transverse 19 25
joints
b) Two layers, of total thickness 38 50
B) Hollow protection (with an air cavity below the lower flange):
1 . Asbestos insulating board screwed to 25 mm asbestos battens 9 12
C) Solid protection:
1 . Concrete, not leaner than 1 :2:4 mix (unplastered):
a) Concrete not assumed to be load bearing, reinforced 3)
b) Concrete assumed to be load bearing
2. Lightweight concrete 4) , not leaner than 1:2:4 (mix) unplastered
25
25
25
25
50
75
50
50
50
50
75
75
25
25
25
25
40
60
n So fixed or designed, as to allow full penetration for mechanical bond.
2) Where wire binding cannot be used, expert advice should be sought regarding alternative methods of support to enable the lower edges
of the plasterboard to be fixed together and to the lower flange, and for the top edge of the plasterboard to be held in position.
3) Reinforcement shall consist of steel binding wire not less than 2.3 mm in thickness or a steel mesh weighing not less than 0.5 kg/m 2 . In
concrete protection, the spacing of that reinforcement shall not exceed 200 mm in any direction.
4) Concrete not assumed to be load bearing, reinforced.
Table 16 Timber Floors — Tongued and Grooved Boarding, or Sheets of Tongued and Grooved
Plywood or Wood Chipboard, of not Less than 21 nun Finished Thickness
(Clause 3.3.2)
Nature of Construction and Materials Minimum TWckness (mm) of Protection For a
Fire Resistance of
Hh lh 2h
(i) m o) (4)
37 mm (minimum) timber joists with a ceiling of:
1. Timber lathing and plaster, plaster of thickness 15
2. Metal lathing and plaster, thickness of plaster:
a) Sanded gypsum plaster (metal lathing grade) 15
b) Lightweight aggregate gypsum plaster 15 13 25
3. One layer of plasterboard with taped and filled joints 12.7
4. Two layers of plasterboard with joints staggered, joints in outer layer 19 31
taped and filled total thickness
5. One layer of plasterboard not less than 9.5 mm thick, finished with:
a) Gypsum plaster 5
b) Sanded gypsum plaster 13
c) Lightweight aggregate gypsum plaster 13
6. One layer of plasterboard not less than 12.7 mm thick, finished with:
a) Gypsum plaster 5
b) Lightweight aggregate gypsum plaster 10
7. One layer of asbestos insulating board with any transverse joints 9 12
backed by fillets of asbestos insulating board not less than 9 mm
thick, or by timber
20 NATIONAL BUILDING CODE OF INDIA
Table 17 Timber Floors — Tongued and Grooved Boarding, or Sheets of Tongued and Grooved
Plywood or Wood Chipboard, of not Less than 15 mm Finished Thickness
(Clause 3.3.2)
Nature of Construction and Materials Minimum Thickness (mm) of Protection for i
Fire Resistance of
VAh lh 2h
(1) (2) (3) (4)
37 mm (minimum) timber joists with a ceiling of:
1 . Timber lathing and plaster, plaster of thickness 1 5
2. Metal lathing and plaster, thickness of plaster for:
a) Sanded gypsum plaster (metal lathing grade) 15
b) Lightweight aggregate gypsum plaster 13 13 25
3 . One layer of plasterboard with taped and filled joints 1 2.7
4. Two layers of plasterboard with joints staggered, joints in outer layer taped 22 31
and filled total thickness
5. One layer of plasterboard not less than 9.5 mm thick, finish with:
a) Gypsum plaster 5
b) Sanded gypsum plaster 15
c) Lightweight aggregate gypsum plaster 13
6. One layer of plasterboard not less than 12.7 mm thick, finished with:
a) Gypsum plaster 5
b) Lightweight aggregate gypsum plaster 10
1. One layer of asbestos insulating board, with any transverse joints backed by 9 12 1 '
fillets of asbestos insulating board not less than 9 mm thick, or by timber
^ Finished on top with 25 mm minimum thick glass fibre or mineral wool laid between joints.
Table 18 Timber Floors — Any Structurally Suitable Flooring of
Timber or Lignocelluloses Boards
(Clause 3.3.2)
Nature of Construction and Materials Minimum Thickness (mm) of Protection for i
Fire Resistance of
V4h lh
(1) (2) (3)
37 mm (minimum) timber joists with a ceiling of:
1 . Timber lathing and plaster, plaster of thickness 1 5
2. Metal lathing and plaster, thickness of plaster for:
a) Sanded gypsum plaster (metal lathing grade) 1 5
b) Lightweight aggregate gypsum plaster 13 19
3. One layer of plasterboard with joints taped and filled and backed by timber 12.7
4. Two layers of plasterboard with joints staggered, joints in outer layer taped 25
and filled total thickness
5. Two layers of plasterboard, each not less than 9.5 mm thick, joints between 5
boards staggered and outer layer finished with gypsum plaster
6. One layer of plasterboard not less than 9.5 mm thick, finish with:
a) Sanded gypsum plaster 13
b) Lightweight aggregate gypsum plaster 15
7. One layer of plasterboard not less than 12.7 mm thick, finished with:
a) Sanded gypsum plaster 15
b) Lightweight aggregate gypsum plaster 1 3
8. One layer of asbestos insulating board with any transverse joints backed by 12
fillets of asbestos insulating board not less than 9 mm thick, or by timber
3.3.3 Steel Construction f f ire j^ s could be ac hi e ved by use of appropriate
Load hearing steel beams and columns of buildings methodology using suitable fire resistance rated
having total covered area of 500 m 2 and above shall be materials alongwith suppression system {see Table 14,
protected against failure/collapse of structure in case Table 15 and also accepted standard [4(5)]}.
PART 4 FIRE AND LIFE SAFETY 21
3.4 General Requirements of All Individual
Occupancies
3.4.1 General
All buildings shall satisfy certain requirements which
contribute, individually and collectively, to the safety
of life from fire, smoke, fumes and panic arising from
these or similar causes. There are, however, certain
general principles and common requirements which
are applicable to all or most of the occupancies.
3.4.2 Exceptions and Deviations
Exceptions and deviations to the general provisions of
requirements of individual occupancies are given as
applicable to each type of occupancy in 6.1 to 6.9. In
case of practical difficulty or to avoid unnecessary
hardship, without sacrificing reasonable safety, the
Authority may grant exemptions from the Code.
3.4.3 Occupation of Buildings under Construction
3.4.3.1 A building or portion of the building may be
occupied during construction, repairs, alterations or
additions only if all means of exit and fire protection
measures are in place and continuously maintained for
the occupied part of the building.
3.4.3.2 A high rise building during construction shall
be provided with the following fire protection
measures, which shall be maintained in good working
condition at all the times:
a) Dry riser of minimum 100 mm diameter pipe
with hydrant outlets on the floors constructed
with a fire service inlet to boost the water in the
dry riser and maintenance should be as per the
requirements laid down in good practice [4(6)].
b) Drums filled with water of 2 000 litres capacity
with two fire buckets on each floor; and
c) A water storage tank of minimum 20 000
litres capacity, which may be used for other
construction purposes also.
3.4.4 Maximum Height
Every building shall be restricted in its height above
the ground level and the number of storeys, depending
upon its occupancy and the type of construction. The
height shall be measured as specified in Part 3
'Development Control Rules and General Building
Requirements'. The maximum permissible height
for any combination of occupancy and types of
construction should necessarily be related to the width
of street fronting the building, or floor area ratios and
the local fire fighting facilities available.
3.4.5 Floor Area Ratio
The comparative floor area ratios for different
occupancies and types of construction are given in
Table 19 (see also Part 3 'Development Control Rules
and General Building Requirements').
Table 19 Comparative Floor Area Ratios for
Occupancies Facing One Public Street
Atleast 9 m Wide
(Clauses 2.6 and 3.4.5)
Occupancy
f^lsic<cifi{*nHftn
Type of Construction
V/iarauiui uuii
Type 1
Type2
Type 3
Type 4
(1)
(2)
(3)
(4)
(5)
Residential
UL
2.0
1.4
1.0
Educational
UL
2.0
1.4
1.0
Institutional
UL
1.5
1.0
0.8
Assembly
UL
1.0
0.7
0.5
Business
UL
2.9
2.3
1.6
Mercantile
8.0
1.8
1.4
1.0
Industrial
7.5
1.9
1.6
1.3
Storage (see Note 5)
6.0
1.5
1.3
1.0
Hazardous (see Note 5)
2.8
1.1
0.9
NP
UL — Unlimited.
NP — Not permitted.
NOTES
1 The FAR values given in this table are subject to overall
restrictions on the heights of buildings in the case of
educational, institutional, assembly, storage and hazardous
occupancies as specified in col 2 of Table 23.
2 This table has been prepared, taking into account the
combustible content in the different occupancies as well as
the fire resistance offered by the type of construction.
3 This table should be modified by the Authority, taking into
account the other aspects as given below:
a) Density in terms of dwelling units per hectare;
b) Traffic considerations;
c) Parking spaces;
d) Local fire fighting facilities; and
e) Water supply, drainage and sanitation requirements.
4 The FAR values specified in this table may be increased
by 20 percent for the following services:
a) A basement or cellar space under a building constructed
on stilts and used as a parking space and air-
conditioning plant room used as accessory to the
principal use;
b) Watchman's booth, pumphouse, garbage shaft, electric
cabin or sub-station and other utility structures meant
for the services of the building under considerations;
c) Projections and accessory buildings as specifically
exempted under the Code; and
d) Staircase room and lift rooms above the topmost storey;
architectural feature; and chimneys and elevated tanks
of dimensions as permissible under the Code; the area
of the lift shaft shall be taken only on one floor.
5 In so far as single storey storage and hazardous occupancies
are concerned, they would be further governed by volume to
plot area ratio (VPR) to be decided by the Authority.
3.4.5.1 Each portion of a building, which is separated
by one or more continuous fire resisting walls, having
a fire resistance of not less than 2 h, extending from
the foundation to 1 m above the roof at all points, may
22
NATIONAL BUILDING CODE OF INDIA
be considered to be a separate building for the
calculation of maximum permissible height and floor
area, provided openings, if any, in the separating
wall are also protected by fire assemblies of not less
than 2 h.
3.4.6 Open Spaces
The open spaces around or inside a building shall
conform to the requirements of Part 3 'Development
Control Rules and General Building Requirements'.
3.4.6.1 For high rise buildings, the following
additional provisions of means of access to the building
shall be ensured (see Part 3 'Development Control
Rules and General Building Requirements'):
a) The width of the main street on which the
building abuts shall not be less than 12 m and
one end of this street shall join another street
not less than 12 m in width;
b) The road shall not terminate in a dead end;
except in the case of residential building, up
to a height of 30 m.
c) The compulsory open spaces around the
building shall not be used for parking; and
d) Adequate passageway and clearances
required for fire fighting vehicles to enter the
premises shall be provided at the main
entrance; the width of such entrance shall be
not less than 4.5 m. If an arch or covered gate
is constructed, it shall have a clear head-room
of not less than 5 m.
3.4.7 Mixed Occupancy
When any building is used for more than one type of
occupancy, then in so far as fire safety is concerned, it
shall conform to the requirements for the occupancies
of higher hazard. Unless the high hazard area is
separated by separating walls of 4 h rating, the
occupancies shall not be treated individually.
3.4.8 Openings in Separating Walls and Floors
At the time of designing openings in separating walls
and floors, particular attention shall be paid to all such
factors as will limit fire spread through these openings
and maintain fire rating of the structural member.
3.4.8.1 For Types 1 to 3 construction, a doorway or
opening in a separating wall on any floor shall be
limited to 5.6 m 2 in area with a maximum height/width
of 2.75 m. Every wall opening shall be protected with
fire-resisting doors having the fire rating of not less
than 2 h in accordance with accepted standard [4(7)].
All openings in the floors shall be protected by vertical
enclosures extending above and below such openings,
the walls of such enclosures having a fire resistance of
not less than 2 h and all openings therein being
protected with a fire-resisting assembly as specified
in 3.4.9.
3.4.8.2 For Type 4 construction, openings in the
separating walls or floors shall be fitted with 2 h fire-
resisting assemblies.
3.4.8.3 Openings in walls or floors which are
necessary to be provided to allow passages of all
building services like cables, electrical wirings,
telephone cables, plumbing pipes, etc, shall be
protected by enclosure in the form of ducts/shafts
having a fire resistance not less than 2 h. The inspection
door for electrical shafts/ducts shall be not less than
2 h and for other services shafts/ducts, the same shall
have fire resistance not less than 1 h. Medium and low
voltage wiring running in shafts/ducts, shall either be
armoured type or run through metal conduits. Further,
the space between the conduits pipes and the walls/
slabs shall be filled in by a filler material having fire
resistance rating of not less than 1 h.
NOTE — In the case of buildings where it is necessary to lower
or lift heavy machinery or goods from one floor to the other, it
may be necessary to provide larger openings in the floor. Such
openings shall be provided with removable covers which shall
have the same strength and fire resistance as the floor.
3.4.8.4 Vertical opening
Every vertical opening between the floors of a building
shall be suitably enclosed or protected, as necessary,
to provide the following:
a) Reasonable safety to the occupants while
using the means of egress by preventing
spread of fire, smoke, or fumes through
vertical openings from floor to floor to allow
occupants to complete their use of the means
of egress. Further it shall be ensured to
provide a clear height of 2 100 mm in the
passage/escape path of the occupants.
b) Limitation of damage to the building and its
contents.
3.4.9 Fire Stop or Enclosure of Openings
Where openings are permitted, they shall not exceed
three-fourths the area of the wall in the case of an
external wall and they shall be protected with fire
resisting assemblies or enclosures having a fire
resistance equal to that of the wall or floor in which
these are situated. Such assemblies and enclosures shall
also be capable of preventing the spread of smoke or
fumes through the openings so as to facilitate the safe
evacuation of building in case of a fire {see also
accepted standard [4(8)]}.
3.4.10 Electrical Installations
For requirements regarding electrical installations from
the point of view of fire safety, reference may be made
PART 4 FIRE AND LIFE SAFETY
23
to good practice [4(9)] {see also Part 8 'Building
Services, Section 2 Electrical and Allied Installations').
3.4.11 Air-conditioning and Ventilation
Air-conditioning and ventilation requirements of
different rooms or areas in any occupancy shall be as
given in Part 8 'Building Services, Section 1 Lighting
and Ventilation and Section 3 Air-conditioning,
Heating and Mechanical Ventilation'.
3.4.11.1 Air-conditioning and ventilating systems
shall be so installed and maintained as to minimize the
danger of spread of fire, smoke or fumes from one
floor to other or from outside to any occupied building
or structure {see C-1.17).
3.4.11.2 Air-conditioning and ventilating systems
circulating air to more than one floor or fire area shall be
provided with dampers designed to close automatically
in case of fire and thereby preventing spread of fire or
smoke and shall be in accordance with the accepted
standard [4(10)]. Such a system shall also be provided
with automatic controls to stop fans in case of fire, unless
arranged to remove smoke from a fire, in which case these
shall be designed to remain in operation.
3.4.11.3 Air-conditioning system serving large places
of assembly (over 1 000 persons), large departmental
stores or hotels with over 100 rooms in a single block
shall be provided with effective means for preventing
circulation of smoke through the system in the case of
a fire in air filters or from other sources drawn into the
system, and shall have smoke sensitive devices for
actuation in accordance with the accepted standards
[4(H)].
3.4.11.4 From fire safety point of view, separate air
handling units for the various floors shall be provided
so as to avoid the hazards arising from spread of fire
and smoke through the air-conditioning ducts. The
requirements of air-conditioning ducts shall be in
accordance with good practice [4(12)].
3.4.11.5 For normal operation, air changes schedule
shall be as given in Part 8 'Building Services, Section 3
Air-conditioning, Heating and Mechanical Ventilation'.
3.4.12 Smoke Venting
3.4.12.1 Smoke venting facilities for safe use of exits
in windowless buildings, underground structures, large
area factories, hotels and assembly buildings (including
cinema halls) shall be automatic in action with manual
controls in addition.
3.4.12.2 Natural draft smoke venting shall utilize roof
vents or vents in walls at or near the ceiling level; such
vents shall be normally open, or, if closed, shall be
designed for automatic opening in case of fire, by
release of smoke sensitive devices.
3.4.12.3 Where smoke venting facilities are installed
for purposes of exit safety, these shall be adequate to
prevent dangerous accumulation of smoke during the
period of time necessary to evacuate the area served,
using available exit facilities with a margin of safety to
allow for unforeseen contingencies. It is recommended
that smoke exhaust equipment should have a minimum
capacity of 12 air changes per hour. Where mechanical
venting is employed, it shall be firesafe.
3.4.12.4 The discharge apertures of all natural draft
smoke vents shall be so arranged as to be readily
accessible for opening by fire service personnel.
3.4.12.5 Power operated smoke exhausting systems
shall be substituted for natural draft* vents only by
specific permission of the Authority.
3.4.13 Heating
Installation of chimney and heating apparatus shall be
in accordance with good practice [4(13)].
3.4.14 Additional Precautions
In addition to the factors covered by 3.4.2 to 3.4.12
there are certain aspects, applicable to particular
occupancies only, which may effect the spread of
fumes and thus the safe evacuation of the building in
case of fire. Some such aspects are:
a) interior finish and decoration;
b) seating, aisles, railings, turnstiles and
revolving doors in places of assembly;
c) service equipment and storage facilities in
buildings other than storage buildings; and
d) hazards on stage, in waiting spaces, projection
booths, etc, in theatres and cinemas.
3.4.15 Surface Interior Finishes
3.4.15.1 The use of combustible surface finishes on
walls (including facade of the building) and ceilings
affects the safety of the occupants of a building. Such
finishes tend to spread the fire and even though the
structural elements may be adequately fire resistant,
serious danger to life may result. It is, therefore,
essential to have adequate precautions to minimize
spread of flame on wall, facade of building and ceiling
surfaces.
The finishing materials used for various surfaces and
decor shall be such that it shall not generate toxic
smoke/fumes.
3.4.15.2 The susceptibility to fire of various types
of wall surfaces is determined in terms of the rate of
spread of flame. Based on the rate of spread of flame,
surfacing material shall be considered as divided into
four classes as follows {see also good practice
[4(14)]}.
24
NATIONAL BUILDING CODE OF INDIA
Class 1 Surfaces of very low flame spread.
Class 2 Surfaces of low flame spread.
Class 3 Surfaces of medium flame spread.
Class 4 Surfaces of rapid flame spread.
3.4.15.3 The uses for which surface materials falling
into various classes shall be adopted in building
construction are given below:
Class 1
Class 2
Class 3
May be May be used in May be used only
used in any any situation, in living rooms and
situation except on walls, bed rooms (but not
facade of the in rooms on the
building, roof) and only as a
staircase and lining to solid walls
corridors and partitions; not
on staircases or
corridors or facade
of the building.
NOTE — Panelling (lining) shall be permitted in a limited
area. It shall not be permitted in a vestibule.
3.4.15.4 Materials of Class 4 which include untreated
wood fibreboards may be used with due fire retardant
treatment as ceiling lining, provided the ceiling is at
least, 2.4 m from the top surface of the floor below,
and the wall surfaces conform to requirements of class
[see Note under 3.4.15.3] Class 4 materials shall not
be used in kitchens, corridors and staircases. Some
materials contain bitumen and, in addition to risk from
spread of fire, emit dense smoke on burning; such
materials shall be excluded from use under these
conditions and shall also not be used for construction
of ceiling where the plenum is used for return air in
air-conditioned buildings [see also 5.1.7(m)].
3.4.15.5 When frames, walls, partitions or floors are
lined with combustible materials, the surfaces on both
sides of the materials shall conform to the appropriate
class, because there is considerable danger from fire
starting and rapidly spreading within the concealed
cavity unknown to the occupants whose escape may
be hampered there by. For detailed information on
materials and details of construction with their fire-
resistance rating, reference may be made to good
practice [4(15)].
3.4.16 Glazing
3.4.16.1 Building of Types 1 to 4 construction shall
employ one of the two types of glazing described
in 3.4. 16.2 and 3.4. 16.3 except that Type 4 construction
may have the alternative of hardwood sashes or frames
or both.
3.4.16.2 Wired glass shall comply with the following
requirements:
a) Wired glass — The wired glass shall be of
minimum half hour fire resistance rating.
b) Sashes and frames — The sashes or frames
or both shall be entirely of iron or other
suitable metal such as stainless steel, securely
bolted or keyed into the wall, except in the
case of panels in internal doors.
c) Setting of glass — The panels of glass shall
be set in rebates or grooves not less than
6.0 mm in width or depth, with due allowance
for expansion, and shall be secured by hard
metal fastenings to the sashes or frames
independently of any cement or putty used
for weather-proofing purposes.
3.4.16.3 Electro-copper glazing shall comply with the
following requirements:
a) Electro-copper glazing — The electro-copper
glazing shall be of minimum half hour fire
resistance rating.
b) Sashes and frames — The sashes or frames
or both shall be entirely of iron or other hard
metal, securely bolted or keyed into the wall,
except when in panels in internal doors.
c) Fixing of sectional lights — The sectional
lights shall be set in rebate or grooves not less
than 6.5 mm in width or depth, with due
allowance for expansion and shall be secured
by hard metal fastenings to the sashes or
frames independently of any lead, cement or
putty used for weather-proofing purposes.
3.4.16.4 Maximum permissible area shall be 5 m 2 for
protection by wired glass or electro-copper glazing.
3.4.16.5 Casement
Hard metal casements, not exceeding 0.8 m 2 fitted with
wired glass or electro-copper glazing in accordance
with 3.4.16.2 and 3.4.16.3, secured to the frames by
hard metal hinges not more than 600 mm apart and by
fastening at top, centre and bottom shall be permissible.
3.4.17 Skylights
3.4.17.1 Wired glass for skylights or monitor lights
shall comply with the following requirements:
a) Wired glass for skylights or monitor lights —
The wired glass for skylights or monitor lights
shall be of minimum half hour fire resistance
rating.
b) Frames and glazing — The frame shall be
continuous and divided by bars spaced at not
more than 700 mm centres. The frame and
bars shall be of iron or other hard metal, and
supported on a curb either of metal or of wood
covered with sheet metal. The toughened glass
PART 4 FIRE AND LIFE SAFETY
25
shall be secured by hard metal fastenings to
the frame and bars independently of any lead,
cement or putty used for weather-proofing
purposes.
3.4.18 Louvers
Louvers wherever provided shall be of minimum half
hour fire resistance rating.
3.4.19 Glass of facade for high rise buildings, etc shall
be of minimum 1 h fire resistance rating.
4 LIFE SAFETY
4.1 General
Every building shall be so constructed, equipped,
maintained and operated as to avoid undue danger to
the life and safety of the occupants from fire, smoke,
fumes or panic during the time period necessary for
escape.
4.2 General Exit Requirements
4.2.1 An exit may be a doorway; corridor; passageway(s)
to an internal staircase, or external staircase, or to a
VERANDAH or terrace(s), which have access to the
street, or to the roof of a building or a refuge area. An
exit may also include a horizontal exit leading to an
adjoining building at the same level.
4.2.2 Lifts and escalators shall not be considered as
exits.
4.2.3 Every exit, exit access or exit discharge shall be
continuously maintained free of all obstructions or
impediments to full use in the case of fire or other
emergency.
4.2.4 Every building meant for human occupancy shall
be provided with exits sufficient to permit safe escape
of occupants, in case of fire or other emergency.
4.2.5 In every building or structure, exits shall comply
with the minimum requirements of this part, except
those not accessible for general public use.
4.2.6 No building shall be so altered as to reduce the
number, width or protection of exits to less than that
required.
4.2.7 Exits shall be clearly visible and the route to
reach the exits shall be clearly marked and signs posted
to guide the occupants of the floor concerned. Signs
shall be illuminated and wired to an independent
electrical circuit on an alternative source of supply.
The sizes and colours of the exit signs shall be in
accordance with good practice [4(16)]. The colour of
the exit signs shall be green.
NOTE — This provision shall not apply to A-2 and A-4
occupancies less than 15 m in height.
4.2.8 The floors of areas covered for the means of exit
shall be illuminated to values not less than 1 ft candle
(10 lux) at floor level. In auditoriums, theatres, concert
halls and such other places of assembly, the
illumination of floor exit/access may be reduced during
period of performances to values not less than 1/5 ft
candle (2 lux).
4.2.9 Fire doors with 2 h fire resistance shall be
provided at appropriate places along the escape route
and particularly at the entrance to lift lobby and stair
well where a 'funnel or flue effect' may be created,
inducing an upward spread of fire to prevent spread of
fire and smoke.
4.2.10 All exits shall provide continuous means of
egress to the exterior of a building or to an exterior
open space leading to a street.
4.2.11 Exits shall be so arranged that they may be
reached without passing through another occupied
unit.
4.3 Occupant Load
For determining the exits required, the number of
persons within any floor area or the occupant load shall
be based on the actual number of occupants, but in no
case less than that specified in Table 20.
4.3.1 Mezzanine
The occupant load of a mezzanine floor discharging
to a floor below shall be added to that floor occupancy
and the capacity of the exits shall be designed for the
total occupancy load thus established.
4.4 Capacities of Exits
4.4.1 The unit of exit width, used to measure the
capacity of any exit, shall be 500 mm. A clear width
of 250 mm shall be counted as an additional half unit.
Clear widths less than 250 mm shall not be counted
for exit width.
NOTE — The total occupants from a particular floor must
evacuate within 2Vi minutes for Type 1 construction,
\Yi minutes for Type 2 construction and 1 minute for Type 3
construction. Size of the exit door/exitway shall be calculated
accordingly keeping in view the travel distance as per
Table 22. /
4.4.2 Occupants per unit exit width shall be in
accordance with Table 21.
4.4.3 Horizontal Exit Allowance
When horizontal exit is provided in buildings of
mercantile, storage, industrial, business and assembly
occupancies, the capacity per storey per unit width of
exit of stairways in Table 21 may be increased by 50
percent and in buildings of institutional occupancy it
may be increased by 100 percent.
26
NATIONAL BUILDING CODE OF INDIA
Table 20 Occupant Load
(Clause 4.3)
SI
Group of Occupancy
Occupant Load, floor
No.
Area in m /Person
(1)
(2)
(3)
i)
Residential (A)
12.5
ii)
Educational (B)
4
iii)
Institutional (C)
15 (see Note})
iv)
Assembly (D)
a) With fixed or loose seats
0.6 (see Note 2)
and dance floors
b) Without seating facilities
1.5 (see Note 2)
including dining rooms
v)
Mercantile (F)
a) Street floor and sales
3
basement
b) Upper sale floors
6
vi)
Business and industrial (E&G)
10
vii)
Storage (H)
30
viii)
Hazardous (J)
10
NOTES
1 Occupant load in dormitory portions of homes for the
aged, orphanages, insane asylums, etc, where sleeping
accommodation is provided, shall be calculated at not less than
7.5 m 2 gross floor area/person.
2 The gross floor area shall include, in addition to the main
assembly room or space, any occupied connecting room or
space in the same storey or in the storeys above or below, where
entrance is common to such rooms and spaces and they are
available for use by the occupants of the assembly place. No
deductions shall be made in the gross area for corridors, closets
or other sub-divisions; the area shall include all space serving
the particular assembly occupancy.
Table 21 Occupants per Unit Exit Width
(Clauses 4.4.2, 4.43 and C-l.6.2)
SI
No.
(1)
Group of
Occupancy
(2)
Number of Occupants
Stairways
(3)
Ramps
(4)
Doors
(5)
i)
ii)
iii)
iv)
v)
vi)
vii)
viii)
ix)
Residential (A)
Educational (B)
Institutional (C)
Assembly (D)
Business (E)
Mercantile (F>
Industrial (G)
Storage (H)
Hazardous (J)
25
25
25
40
50
50
50
50
25
50
50
50
50
60
60
60
60
30
75
75
75
60
75
75
75
75
40
4.5 Arrangement of Exits
4.5.1 Exits shall be so located that the travel distance
on the floor shall not exceed the distance given in
Table 22.
4.5.2 The travel distance to an exit from the dead end
of a corridor shall not exceed half the distance specified
in Table 22, except in assembly and institutional
occupancies in which case it shall not exceed 6 m.
4.5.3 Whenever more than one exit is required for any
room space or floor of a building, exits shall be placed
as remote from each other as possible and shall be
arranged to provide direct access in separate directions
from any point in the area served.
Table 22 Travel Distance for Occupancy and
Type of Construction
(Clauses 4.4.1, 4.5.1 and 4.5.2)
SI
No.
Group of Occupancy
Maximum Travel Distance
Construction
Types 1 & 2
Types 3 & 4
m
m
(1)
(2)
(3)
(4)
i)
Residential (A)
30.0
22.5
ii)
Educational (B)
30.0
22.5
iii)
Institutional (C)
30.0
22.5
iv)
Assembly (D)
30.0
30.0
v)
Business (E)
30.0
30.0
vi)
Mercantile (F)
30.0
30.0
vii)
Industrial (G)
45.0
i)
viii)
Storage (H)
30.0
i)
ix)
Hazardous (J)
22.5
D
NOTES
1 For fully sprinklered building, the travel distance may be
increased by 50 percent of the values specified,
2 Ramps shall be protected with automatic sprinkler system
and shall be counted as one of the means of escape.
Construction of type 3 or 4 is not permitted.
4.6 Number of Exits
4.6.1 General
The general requirements of number of exits shall
supplement the requirement of different occupancies
in 6.1 to 6.9.
4.6.2 All buildings, which are 1 5 m in height or above,
and all buildings used as educational, assembly,
institutional, industrial, storage, and hazardous
occupancies and mixed occupancies with any of the
aforesaid occupancies, having area more than 500 m 2
on each floor shall have a minimum of two staircases.
They shall be of enclosed type; at least one of them
shall be on external walls of buildings and shall open
directly to the exterior, interior open space or to an
open place of safety. Further, the provision or otherwise
of alternative staircases shall be subject to the
requirements of travel distance being complied with.
4.7 Doorways
4.7.1 Every exit doorway shall open into an enclosed
stairway or a horizontal exit of a corridor or passageway
providing continuous and protected means of egress.
PART 4 FIRE AND LIFE SAFETY
27
4.7.2 No exit doorway shall be less than 1 000 mm in
width except assembly buildings where door width
shall be not less than 2 000 mm. Doorways shall be
not less than 2 000 mm in height.
4.7.3 Exit doorways shall open outwards, that is, away
from the room, but shall not obstruct the travel along
any exit. No door, when opened, shall reduce the
required width of stairway or landing to less than
900 mm; overhead or sliding doors shall not be
installed.
NOTE — In the case of buildings where there is a central
corridor, the doors of rooms shall open inwards to permit
smooth flow of traffic in the corridor.
4.7.4 Exit door shall not open immediately upon a
flight of stairs; a landing equal to at least the width of
the door shall be provided in the stairway at each
doorway; the level of landing shall be the same as that
of the floor which it serves.
4.7.5 Exit doorways shall be openable from the side
which they serve without the use of a key.
4.7.6 Mirrors shall not be placed in exit ways or exit
doors to avoid confusion regarding the direction of exit.
4.8 Corridors and Passageways
4.8.1 Exit corridors and passageways shall be of width
not less than the aggregate required width of exit
doorways leading from them in the direction of travel
to the exterior.
4.8.2 Where stairways discharge through corridors and
passageways, the height of corridors and passageways
shall be not less than 2.4 m.
4.8.3 All means of exit including staircases lifts lobbies
and corridors shall be adequately ventilated.
4.9 Internal Staircases
4.9.1 Internal stairs shall be constructed of non-
combustible materials throughout.
4.9.2 Internal stairs shall be constructed as a self-
contained unit with an external wall of the building
constituting at least one of its sides and shall be
completely enclosed.
4.9.3 A staircase shall not be arranged round a lift shaft.
4.9.4 Hollow combustible construction shall not be
permitted.
4.9.5 No gas piping or electrical panels shall be
allowed in the stairway. Ducting in stairway may be
permitted if it is of 1 h fire resistance rating.
4.9.6 Notwithstanding the detailed provision for exits
in accordance with 4.3, 4.4 and 4.5, the following
minimum width shall be provided for staircases:
a) Residential buildings (dwellings) 1.0 m
b) Residential hotel buildings 1.5 m
c) Assembly buildings like auditorium, 2.0 m
theatres and cinemas
d) Educational buildings up to 30 m in 1.5 m
height
e) Institutional buildings like hospitals 2.0 m
f) All other buildings 1.5 m
4.9.7 The minimum width of tread without nosing
shall be 250 mm for internal staircase of residential
buildings. This shall be 300 mm for assembly, hotels,
educational, institutional, business and other buildings.
The treads shall be constructed and maintained in a
manner to prevent slipping.
4.9.8 The maximum height of riser shall be 190 mm
for residential buildings and 150 mm for other buildings
and the number shall be limited to 15 per flight.
4.9.9 Handrails shall be provided at a height of
1 000 mm to be measured from the base of the middle
of the treads to the top of the handrails. Balusters/railing
shall be provided such that the width of staircase does
not reduce {see Fig. 1).
4.9.10 The number of people in between floor landings
in staircase shall not be less than the population on
each floor for the purpose of design of staircase. The
design of staircase shall also take into account the
following:
a) The minimum headroom in a passage under
the landing of a staircase and under the
staircase shall be 2.2 m.
b) For building 15 m in height or more, access
to main staircase shall be through a fire/smoke
check door of a minimum 2 h fire resistance
rating. Fire resistance rating may be reduced
to 1 h for residential buildings (except hotels
and starred hotels).
c) No living space, store or other fire risk shall
open directly into the staircase or staircases.
d) External exit door of staircase enclosure at
ground level shall open directly to the open
spaces or through a large lobby, if necessary,
e) The main and external staircases shall be
continuous from ground floor to the terrace
level.
f) No electrical shafts/ AC ducts or gas pipes, etc,
shall pass through or open in the staircases.
Lifts shall not open in staircase.
g) No combustible material shall be used for
decoration/wall paneling in the staircase.
h) Beams/columns and other building features
shall not reduce the head room/width of the
staircase.
28
NATIONAL BUILDING CODE OF INDIA
BLUSTER
All dimensions in millimetres.
Fig. 1 Typical Detail for Handrail/Blusters of a Staircase
j) The exit sign with arrow indicating the way
to the escape route shall be provided at a
suitable height from the floor level on the wall
and shall be illuminated by electric light
connected to corridor circuits. All exit way
marking signs should be flush with the wall
and so designed that no mechanical damage
shall occur to them due to moving of furniture
or other heavy equipments. Further, all
landings of floor shall have floor indicating
boards prominently indicating the number of
floor as per bye-laws.
The floor indication board shall be placed on
the wall immediately facing the flight of stairs
and nearest to the landing. It shall be of size
not less than 0.5 m x 0.5 m.
k) Individual floors shall be prominently
indicated on the wall facing the staircases.
m) In case of single staircase it shall terminate
at the ground floor level and the access to
the basement shall be by a separate staircase.
The second staircase may lead to basement
levels provided the same is separate at
ground level by ventilated lobby with
discharge points to two different ends
through enclosures.
4.10 Pressurization of Staircases (Protected Escape
Routes)
4.10.1 Though in normal building design,
compartmentation plays a vital part in limiting the
spread of fire, smoke will readily spread to adjacent
spaces through the various leakage openings in the
compartment enclosure, such as cracks, openings
around pipes ducts, airflow grills and doors, as perfect
sealing of all these openings is not possible. It is smoke
and toxic gases, rather than flame, that will initially
obstruct the free movement of occupants of the
building through the means of escape (escape routes).
Hence the exclusion of smoke and toxic gases from
the protected routes is of great importance.
4.10.2 Pressurization is a method adopted for protected
escape routes against ingress of smoke, especially in
high-rise buildings. In pressurization, air is injected
into the staircases, lobbies or corridors, to raise their
pressure slightly above the pressure in adjacent parts
of the building. As a result, ingress of smoke or toxic
gases into the escape routes will be prevented. The
pressurization of staircases shall be adopted for high
rise buildings and building having mixed occupancy/
multiplexes having covered area more than 500 m 2 .
4.10.3 The pressure difference for staircases shall be
as under:
PART 4 FIRE AND LIFE SAFETY
29
Building
Pressure Difference
Height
<*•*" ^*" ->»
Reduced Emergency
Operation Operation
(Stage 1 of (Stage 2 of a
a 2-Stage 2-Stage System
System) or Single
Stage System)
(Pa) (Pa)
Less than 15 m
8 50
15 m or above
15 50
If possible, the same levels shall be used for lobbies
and corridors, but levels slightly lower may be used
for these spaces if desired. The difference in
pressurization levels between staircase and lobbies (or
corridors) shall not be greater than 5 Pa.
4.10.4 Pressurization system may be of two types:
a) Single-stage, designed for operation only in
the event of an emergency, and
b) Two-stage, where normally a level of
pressurization is maintained in the protected
escape routes and an increased level of
pressurization can be brought into operation
in an emergency.
4.10.5 The normal air-conditioning system and the
pressurization system shall be treated as an integral
one, especially for a two-stage system. When the
emergency pressurization is brought into action, the
following changes in the normal air-conditioning
system shall be effected:
a) Any re-circulation of air shall be stopped and
all exhaust air vented to atmosphere;
b) Any air supply to the spaces/areas other than
escape routes shall be stopped;
c) The exhaust system may be continued
provided:
1) the positions of the extraction grills
permit a general air flow away from the
protected escape route entry;
2) the construction of the ductwork and fans
is such that, it will not be rendered
inoperable by hot gases and smoke; and
3) there is no danger of spread of smoke to
other floors by the path of the extraction
system which can be ensured by keeping
the extraction fans running.
4.10.6 The pressurization system can be
interconnected with the automatic/manual fire alarm
system for actuation.
4.10.7 It will be desirable to have all the staircases in
a building pressurized, if pressurization system is to
be resorted to. The use of pressurized and naturally
ventilated staircases in the same building may introduce
difficulties and hence shall be avoided. Under no
circumstances shall a pressurized staircase be
connected by a corridor or lobby to an un-pressurized
staircase. Wherever pressurized staircase is to be
connected to un-pressurized area, the two areas shall
be segregated.
4.11 External Stairs
An external staircase is desirable to be provided for
high rise buildings.
External stairs, when provided shall comply the
following:
4.11.1 External stairs shall always be kept in sound
operable conditions.
4.11.2 All external stairs shall be directly connected
to the ground.
4.11.3 Entrance to the external stairs shall be separate
and remote from the internal staircase.
4.11.4 Care shall be taken to ensure that no wall
opening or window opens on to or close to an external
stairs.
4.11.5 The route to the external stairs shall be free of
obstructions at all times.
4.11.6 The external stairs shall be constructed of non-
combustible materials, and any doorway leading to it
shall have the required fire resistance.
4.11.7 No external staircase, used as a fire escape, shall
be inclined at an angle greater than 45° from the
horizontal.
4.11.8 External stairs shall have straight flight not less
than 1 250 mm wide with 250 mm treads and risers
not more than 190 mm. The number of risers shall be
limited to 15 per flight.
4.11.9 Handrails shall be of a height not less than
1 000 mm and not exceeding 1 200 mm. There shall
be provisions of balusters with maximum gap of
150 mm.
4.11.10 The use of spiral staircase shall be limited to
low occupant load and to a building not exceeding 9 m
in height.
A spiral stair case shall be not less than 1 500 mm in
diameter and shall be designed to give adequate
headroom.
4.11.11 Unprotected steel frame staircase will not be
accepted as means of escape. However, steel staircase
in an enclosed fire rated compartment of 2 h will be
accepted as means of escape.
30
NATIONAL BUILDING CODE OF INDIA
4.12 Horizontal Exits
4.12.1 The width of horizontal exit shall be same as
for the exit doorways.
4.12.2 A horizontal exit shall be equipped with at least
one fire/smoke door of minimum 1 h fire resistance,
of self-closing type. Further, it is required to have direct
connectivity to the fire escape staircase for evacuation.
4.12.3 For buildings more than 24 m in height, refuge
area of 15 m 2 or an area equivalent to 0.3 m 2 per person
to accommodate the occupants of two consecutive
floors, whichever is higher, shall be provided as under:
The refuge area shall be provided on the periphery of
the floor or preferably on a cantilever projection and
open to air at least on one side protected with suitable
railings.
a) For floors above 24 m and Up to 39 m —
One refuge area on the floor immediately
above 24 m.
b) For floors above 39 m — One refuge area on
the floor immediately above 39 m and so on
after every 15 m. Refuge area provided in
excess of the requirements shall be counted
towards FAR.
NOTE — Residential flats in multi-storied building with
balcony, need not be provided with refuge area,
however flats without balcony shall provide refuge area
as given above.
4.12.4 Where there is a difference in level between
connected areas for horizontal exits, ramps, not more
than 1 in 10 m slope shall be provided; steps shall not
be used.
4.12.5 Doors in horizontal exits shall be openable at
all times from both sides.
4.13 Fire Tower
Fire towers are the preferred type of escape route for
storeyed buildings and these shall be considered as the
safest route for escape. Their number, location and size
shall depend on the building concerned, and its
associated escape routes.
4.13.1 In high rise buildings with over 8 storeys or
24 m in height, at least one required means of egress
shall preferably be a fire tower.
4.13.2 The fire towers shall be constructed of walls
with a 2 h fire resistance rating without openings other
than the exit doorways, with platforms, landings and
balconies having the same fire-resistance rating.
4.14 Ramps
4.14.1 Ramps shall comply with all the applicable
requirements for stairways regarding enclosure,
capacity and limiting dimensions except where
specified in 6.1 to 6.9 for special uses and occupancies.
4.14.2 The slope of a ramp shall not exceed 1 in 10.
In certain cases steeper slopes may be permitted but in
no case greater than 1 in 8.
4.14.3 For all slopes exceeding 1 in 10 and wherever
the use is such as to involve danger of slipping, the
ramp shall be surfaced with approved non-slipping
material.
4.15 Fire Lifts
4.15.1 Where applicable, fire lifts shall be provided
with a minimum capacity for 8 passengers and fully
automated with emergency switch on ground level. In
general, buildings 15 m in height or above shall be
provided with fire lifts.
4.15.2 In case of fire, only fireman shall operate the fire
lift. In normal course, it may be used by other persons.
4.15.3 Each fire lift shall be equipped with suitable
inter-communication equipment for communicating
with the control room on the ground floor of the
building.
4.15.4 The number and location of fire lifts in a
building shall be decided after taking into consideration
various factors like building population, floor area,
compartmentation, etc.
4.16 Emergency and Escape Lighting
4.16.1 Emergency lighting shall be powered from a
source independent of that supplying the normal
lighting [see good practice [4(17)].
Escape lighting shall be capable of:
a) Indicating clearly and unambiguously the
escape routes,
b) Providing adequate illumination along such
routes to allow safe movement of persons
towards and through the exits,
c) Ensuring that fire alarm call points and fire-
fighting equipments provided along the
escape routes can be readily located.
4.16.2 The horizontal luminance at floor level on the
centreline of an escape route shall be not less than
10 lux. In addition, for escape routes up to 2 m wide,
50 percent of the route width shall be lit to a minimum
of 5 lux.
4.16.3 The emergency lighting shall be provided to
be put on within 1 s of the failure of the normal lighting
supply.
4.16.4 Escape lighting luminaries should be sited to
cover the following locations:
PART 4 FIRE AND LIFE SAFETY
31
a) Near each intersection of corridors,
b) at each exit door,
c) Near each change of direction in the escape
route,
d) Near each staircase so that each flight of stairs
receives direct light,
e) Near any other change of floor level,
f) Outside each final exit and close to it,
g) Near each fire alarm call point,
h) Near fire-fighting equipment, and
j) To illuminate exit and safety signs as required
by the enforcing authority.
NOTE — For the purposes of this clause 'near' is
normally considered to be within 2 m measured
horizontally.
4.16.5 Emergency lighting systems shall be designed
to ensure that a fault or failure in any one luminaire
does not further reduce the effectiveness of the
system.
4.16.6 The luminairies shall be mounted as low as
possible, but at least 2 m above the floor level.
4.16.7 Signs are required at all exits, emergency
exits and escape routes, which should comply with
the graphic requirements of the relevant Indian
Standards.
4.16.8 Emergency lighting luminaires and their fittings
shall be of non-flammable type.
4.16.9 It is essential that the wiring and installation of
the emergency lighting systems are of high quality so
as to ensure their perfect serviceability at all times.
4.16.10 The emergency lighting system shall be
capable of continuous operation for a minimum
duration of 1 h and 30 m even for the smallest
premises.
4.16.11 The emergency lighting system shall be well
maintained by periodical inspections and tests so as to
ensure their perfect serviceability at all times.
4.17 Illumination of Means of Exit
Staircase and corridor lights shall conform to the
following:
a) The staircase and corridor lighting shall be
on separate circuits and shall be independently
connected so that it could be operated by one
switch installation on the ground floor easily
accessible to fire fighting staff at any time
irrespective of the position of the individual
control of the light points, if any. It should be
of miniature circuit breaker type of switch so
as to avoid replacement of fuse in case of
crisis;
b) Staircase and corridor lighting shall also
be connected to alternative supply. The
alternative source of supply may be provided
by battery continuously trickle charged from
the electric mains; and
c) Suitable arrangements shall be made by
installing double throw switches to ensure that
the lighting installed in the staircase and the
corridor does not get connected to two sources
of supply simultaneously. Double throw
switch shall be installed in the service room
for terminating the stand-by supply.
4.18 Fire Detection and Warning
In buildings of such size, arrangement or occupancy
where a fire may not itself provide adequate warning
to occupants, automatic fire detection and alarm
facilities shall be provided, where necessary, to warn
occupants early of the existence of fire, so that they
may escape, and to facilitate the orderly conduct of
fire exit drills.
4.18.1 The fire detection system shall be in accordance
with accepted standards [4(18)]. Guidelines for
selection of various types of fire detectors for different
occupancies and their installation and maintenance
shall be in accordance with [4(19)].
4.18.2 The requirements of fire detection and alarm
systems are covered for each occupancy in Table 23
and under 6.1 to 6.9; attention is also drawn to such
requirements in case of high rise buildings (15 m or
more in height) as given in Annex C.
5 FIRE PROTECTION
5.1 Fire Extinguishers/Fixed Fire Fighting
Installations
5.1.1 All buildings depending upon the occupancy use
and height shall be protected by fire extinguishers, wet
riser, down-comer, automatic sprinkler installation,
high/medium velocity water spray, foam, gaseous or
dry powder system in accordance with the provisions
of 5.1.2 to 5.1.9.
5.1.2 These fire extinguf&hers/fixed installations shall
be in accordance with accepted standards [4(20)]. The
typical requirements of fire extinguishers/wet riser/
down-comer installation and capacity of water storage
tanks and fire pumps, etc shall be as specified in
Table 23. The requirements regarding size of mains/
risers shall be as given in Table 24. The typical
arrangements of down-comer and wet riser installations
are shown in Fig. 2 and Fig. 3. The wet riser shall be
designed for zonal distribution ensuring that unduly
high pressures are not developed in risers and hose-
pipes.
32
NATIONAL BUILDING CODE OF INDIA
-AIR RELEASE VALVE
3 WAY FIRE
SERVICE INLET
SLUCE AND NR
TERRACE TANK
FOR FIRE FIGHTING/
DOMESTIC SUPPLY -
DRAIN VALVE
Fig. 2 Typical Arrangement of Down-Comer for Building Above 15 m
but not Exceeding 30 m in Height
PART 4 FIRE AND LIFE SAFETY
33
O. H. TANK
HXKh
6 6 6 6 6 (Jltl
ra
8
6 6 6 6 oi^
HP - HYDRANT PUMP /
MAIN ELECTRIC PUMP
JP - JOCKEY PUMP
DP - DIESEL PUMP
SP - SPRINKLER PUMP
SH - SUCTION HEADER
DH - DLIVERY HEADER
R - PIPE TO RISER
Y - PIPE TO YARD
HYDRANT
S - PIPE TO SPRINKLER
SYSTEM
AV - AIR VESSEL
iCV- INSTALLATION
CONTROL VALVE
6 6 6 6 6 6!^
JL
SPRINKLER RISER -^
SPRINKLER LINE TEST DRAIN
1
1-1
1
1 ''iii
i4J
It
WET RISER
O C C\ 9 —
6 6 6 O O l^
6 6 1??
6 6 6
6 6 6 6 6 6|trn_..
FIRST FLOOR
YARD
HYDRANT
H^PJmM s
^! j ♦♦ TPFT ni DP
666606666
GROUND FLOOR
HT^o
3"^
ICV
AV l
TO DRAIN SUMP gl
TT1
an.
! fill —
!!
8
— 4 HOSE REEL
4 SINGLE HEAD
LANDING VALVE
f AIR RELEASE VALVE
_^j_ SLUICE VALVE
-*- NON - RETURN VALVE
-s- FLOW SWITCH
=y SPRINKLER HEAD
CABLE TO ANNUNCIATION
PANEL
CABLE CONDUITE FOR
HOOTER
CABLE CONDUIT FOR
MANUAL CALL BOX
Wi -
H 1
i
Hi Hi
HOOTER
HZ] MANUAL CALL BOX
1!!!
I
IIIMi
|IIHI
illllli
mm
,ihii
I — I FIRE BRIGADE DRAW
FROM TANK
|—< FIRE BRIGADE INLET
TANK FILLING
fl=ipr
hill
FIRE ALARM PANEL WITH
BATTERY BACK-UP AND
P.A. SYSTEM
ZONAL SPRINKLER
ANNUNCIATION PANEL
UG FIRE
TANK
Fig. 3 Typical Arrangement of Wet Riser and Total Sprinkler System of Building
Other than Appartment Exceeding 30 m in Height
34
NATIONAL BUILDING CODE OF INDIA
*0
>
H
>
r
w
Table 23 Minimum Requirements for Fire Fighting Installations
(Clauses 4.18.2, 6.1.2, 6.2.3, 6.3.2, 6.4.3, 6.5.2, 6.5.2.1, 6.5.2.2, 6.5.2.3, 6.5,2.4, 6.5.2.5, 6.6.2, 6.7.2, 6.8.2 and 6.9.2)
SI Type of Building
No. Occupancy
Type of Installation
Water Supply
(ml)
Pump Capacity
(in I/min)
Fire
Ex tin-
gusher
Hose
Reel
Dry
Riser
(see
Note 6)
Wet
Riser
Down- Yard
Comer Hydrant
Automatic
Sprinkler
System
Manually
Operated
Electric
Fire Alarm
Systems
Automatic
Detection
and Alarm
System
Underground
Static Water
Storage
Tank
Terrace
Tank
Pump Near
Underground
Static Water
Storage Tank
(Fire Pump)
with Minimum
Pressure of
3.5 kg/cm 2
at
Terrace Level
At the
Terrace
Tank Level
with
Minimum
Pressure
of
2.0 kg/cm 2
(1) (2) (3)
(4)
(5)
(6)
(7) (8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
RESIDENTIAL BUILDINGS (A)
a) Lodging or Rooming
Houses (A-l)
(see Note 1)
1) Less than 15 m in
height
i) Up to 15 rooms
ii) More than 15 and
up to 30 rooms
iii) More than
30 rooms
NR NR NR
NR NR
NR
NR
NR
NR
NR
NR
R
(see Note 2)
NR
NR
R
(see Note 2)
NR
NR
R
(see Note 2)
R
(see Note 5)
NR
NR
NR
NR
NR
NR
5 000
(see Note 3)
5 000
(5 000)
(see Note 4)
10 000
(5 000)
(see Note 4)
NR
NR
NR
NR
450
(450)
(see Note 4)
450
(450)
(see Note 4)
b) One or two Family
Private Dwellings
(A-2)
(see Note 1)
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
in
Table 23 — Continued
(l)
(2)
(3) (4) (5) (6) (7)
(8) (9)
(10) (II) (12)
(13)
(14)
(15)
c) Dormitories (A-3)
Apartment
Houses (A-4)
1) Less than 15 m
in height
2) 15 m and above but
not exceeding 35 m
in height
R R NR NR NR
R R NR NR R
NR R
(see Note 2)
NR
NR
NR R R NR
(see Note 2) (see Note 7)
NR
NR
5 000
(5 000)
(see Note 4)
25 000
NR
NR
450
(450)
(see Note 4)
900
3) Above 35 m but not
exceeding 45 m in
height
4) Above 45 m in height
but not exceeding
60 m in height
R R NR R NR
R R NR R NR
NR
R
(see Notes
2 and 8)
R
NR
NR
75 000
75 000
5 000
(5 000)
(see Note 4)
10 000
(see Note 1 9)
(see Note 20)
NR
NR
5) Above 60 m
in height
R R NR R NR
100 000
25 000 (see Note 21) NR
d) Hotels (A-5)
1) Less than 15 m
in height
2
>
1
>
r
w
d
F
o
o
3
w
o
i) Covered area not
exceeding 300 m 2
on each floor
ii) Covered area
exceeding 300 m 2
but not more
1 000 m 2 on
each floor
iii) Covered area
exceeding
1 000 m 2 on
each floor
R R
R R
R R
NR NR NR
NR R NR
(see
Note 5)
NR R NR
(see
Note 9)
NR R
(see Note 2)
NR R
(see Note 2)
NR
R R R
(see Note 10)
NR
5 000
NR
450
(see Note 2)
(see Note 3)
10 000 for
10 000
(see Notes 5
NR
every 500 m 2
(see Note 2)
and 19)
covered area
subject to
minimum of
50 000
(see Note 5)
100 000
10 000
(see Notes 9
NR
(see Note 9)
(see Note 2)
and 19)
5
O
r
c/3
3
Table 23 — Continued
(i)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
2) 15 m and above but
not exceeding 30 m
3) Above 30 m in
height
NR
NR
e) Hotels (A-6) R R NR R
EDUCATIONAL BUILDINGS (B) (see Note 12)
1) Less than 15 m in height
R NR NR NR
i) Ground plus one
storey
ii) Ground plus two
or more storeys
2) 15 m and above but not
exceeding 30 m in height
NR
INSTITUTIONAL BUILDINGS (C) (see Note 12)
a) Hospitals, Sanatoria
and Nursing Homes
(C-l)
1) Less than 15 m in height
with plot area up to
1 000 m 2
i) Up to ground plus R R NR
one storey, with
no beds
ii) Up to ground plus R R NR
one storey with beds
iii) Ground plus two R R NR
or more storeys,
with no beds
iv) Ground plus two or R R NR
more storeys, with
beds
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
R R
(see Note 10)
R R
(see Note 10)
R R
(see Note 10)
NR R
(see Note 2)
NR NR NR NR
NR
NR
NR
NR
NR
R
(see Note 2)
R
(see Note 2)
R
(see Note 2)
R
(see Note 2)
R
(see Note 2)
R
(see Note 2)
NR
NR
NR
NR
NR
NR
NR
150 000
200 000
200 000
NR
NR
NR
NR
NR
NR
50 000
20 000
20 000
20 000
5 000
(see Note 3)
10 000
(5 000)
(see Note 4)
25 000
{see Note 20) NR
(w Note 21) NR
(see Note 22) NR
NR
NR
NR
450
(see Note 3)
450
(450)
(see Note 4)
900
2 500
NR
NR
(2 500)
(see Note 4)
5 000
NR
450
(5 000)
(450)
(see Note 4)
(see Note 4)
5 000
NR
450
(5 000)
(450)
(see Note 4)
(see Note 4)
5 000
(see Note 19)
NR
(5 000)
(see Note 4)
00
Table 23 — Continued
0)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
I
2) Less than 15 m in height
wiih plot area more
than i 000 m 2
3) 1 5 rn and above but not
exceeding 24 m in height
4) Above 24 m and not
exceeding 30 m in height
b) Custodial (C-2) t and
Penal and Plental (C-3)
1) Less than 10 m in
height
i) Up to 300 persons
ii) More than 300
persons
2) 10 in and above but
not exceeding 15 m
in height
3) 15m and above but
not exceeding 24 m in
height
4) 24 m and above but
not exceeding 30 m in
height
NR
NR
NR
NR NR
NR NR
NR
NR
R NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
R
(see Note 2)
(see Note il)
(see Note 11)
R
(see Note 2)
R
(see Note 2)
R
(see Note 2)
(see Note 11)
(see Note 11)
NR
NR
1 00 000
100 000
150 000
NR
NR
50 000
75 000
100 000
10 000
20 000
(see Note 19)
20 000 (see Note 21)
NR
(see Note 20) NR
NR
10 000
(5 000)
(see Note 4)
NR
450 (900)
(see Note 4)
15000
(5 000)
(see Note 4)
NR
450 (900)
(see Note 4)
5000
(5 000)
(see Note 4)
(see Note 20)
NR
10 000
(see Note 20)
NR
20000
(see Note 21)
NR
p
I
n
o
©
ASSEMBLY BUILDINGS (D) (see Note 12)
a) Buildings
(D-l to D-5)
1) Less than 10 rn in height
i) Up to 300 persons R R
NR NR
NR
(see Note 2)
NR
NR
10000
(5 000)
(see Note 4)
NR
450
(450)
(see Note 4)
>
o
r 1
<Z3
m
H
Table 23 — Continued
(1)
(2)
(3)
(4) (5)
(6)
(7)
(8)
(9)
(10)
CM
ii) More than
300 persons
2) Above 10m but not
exceeding 15 m in height
3) Above 15 m but not
exceeding 24 m in height
4) Above 24 m but not
exceeding 30 m in height
b) Multiplex D-6
c) D-7
BUSINESS BUILDINGS (E)
1) Less than 10 m in
height
2) Above 10 m but not R
exceeding 15 m in
height
3) Above 15 m arid up to R
24 m in height
4) Above 24 m and up to R
30 m in height
5) Above 30 m in height R
MERCANTILE BUILDINGS (F)
a) F-l & F-2
(see Note 12)
1) Less than 15 m in height
i) Ground plus one R
storey, with total
covered area not
exceeding 500 m 2
NR NR
NR
NR
NR
R NR
For details see 6.4.8
NR NR
NR R
(see Note 2)
NR NR R
(see Note 2)
NR R R
(.see Note 11)
NR R R
(see Note 10)
NR R R
(see Note 10)
R
NR
NR
R
NR
R
(see Note 2)
R
R
NR
R
NR
NR
R
(see Note 2)
R
R
NR
R
NR
R
R
(see Note 11)
R
R
NR
R
NR
R
R
(see Note 10)
R
^ R
NR
R
NR
R
R
(see Note 10)
R
NR R
(see Note 2)
NR
(11)
NR
NR
R
R
R
NR
(12)
NR
50000
75 000
100 000
200 000
NR
50000
75 000
100 000
200000
NR
(13)
(14)
(15)
15 000
(5 000)
(see Note 4)
5 000
(5 000)
(see Note 4)
10 000
20 000
20 000
10000
(5 000)
(see Note 4)
5000
(5 000)
(see Note 4)
10 000.
20000
20 000
5000
(5 000)
(see Note 4)
NR
900
(see Note 20) 450
(450)
(see Note 4)
(see Note 20) NR
(see Note 21) NR
(see Note 22) NR
NR
450
(450)
(see Note 4)
(see Note 20) 450
(450)
(see Note 4)
(see Note 20) NR
(see Note 21)
(see Note 22)
NR
NR
NR
450
(450)
(see Note 4)
Table 23 — Continued
$
_0) Ph (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15)
ii) Ground plus one RRNRNRRNRR R NR NR 25 000 NR 900
storey and covered ( see Note 2)
area exceeding
500 m 2
hi) More than ground R R R NR R NR R R NR NR
plus one storey { see Note 2)
2) Above 15 m but not R R NR R NR NR R R R 100 000
exceeding 24 m in ( see Note 1 1)
height
5000
(5 000)
{see Note 4)
NR
10 000
{see Note 20)
10 000
(.see Note 21)
10000
(see Note 21)
J* ii) Built up area more RRNRNRRNR R NR NR NR
^ than 100 m 2 and (, e£ Note 2)
O up to 500 m 2
Z ■ '
iii) Built up area more R JR NR R R R R NR R 100 000
W than ^m m 2
than 500 m z {see Note 7)
5000
{see Note 3)
NR
5000
(5 000)
{see Note 4)
NR
10000
{set
? Note 20)
i) Built up area
uptolOOm 2
R
R
NR
NR
NR
NR
ii) Built up area more
than 100 m 2 and
up to 500 m 2
R
R
NR
NR
NR
NR
900
NR
3) Above 24 m but not RRNRRNRR R R R 150 000 10 000 {see Note 21) NR
exceeding 30 m in ( see Note 1 0)
height
b) Underground shopping R RNRR NR R R R R 1 50 000 10000 {see Note 2 1 ) NR
complex (F-3) ( Jee Note 10)
(jeeNotel3)
INDUSTRIAL BUILDINGS (G) {see Note 14)
a) Low Hazard (G-l)
(see Note 15)
i) Builtuparea R NR NR' NR NR NR R NR NR NR 5 000 NR 450
uptolOOm 2 (see Note 2) { see Note 3) (see Note 3)
450
450
2 b) Moderate Hazard
g (G-2) {see Note 14)
Q i) Builtuparea RRNRNRNRNR R NR NR NR 10000 NR 450
W
£ u> Built up area more R R NR NR NR NR R NR NR NR 10 000 NR 900
gg Table 23 — Continued
w _ .
2 0) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) ( 13 ) ( 14 ) i^L
S iii) Built up area more R R NR R R R R R R 75 000 20 000 (see Note 20) 900
W than 500 m 2 and (see Note 7)
£ up to 1 000 m 2
g iv) Built up area more RRNRR R R R R R 100000 20 000 (see Note 20) 900
|j than 1000 m 2 (see Note 7)
CO
*j c) High Hazard (G-3)
3 (we Note 16)
i) Builtuparea R R NR NR NR NR R NR NR NR 5 000 NR 450
up to 50 m 2
ii) Built up area more R R NR NR NR NR R NR R NR 5 000 NR 450
than 50 m 2 and
up to 150 m 2
iii) Built up area more RRNRR NR NR R NR R 25 000 10 000 (see Note 19) 450
than 150 m 2 and
up to 300 m 2
iv) Built up area more RRNRR NR R R R R 50 000 20 000 (see Note 19) 900
than 300 m 2 and
up to 500 m 2
v) Built up area more R R NR R R R R R R 100 000 20 000 (see Note 20) 900
than 500 m 2 (we Note 7)
STORAGE BUILDINGS (H) (see Note 17)
1) Below 15 m in height R R NR NR NR NR R NR NR 25 000 5 000 (see Note 19) 450
and covered area less
than 250 m 2 ^
2) Below 15 m in height
and covered area more
than 250 m 2
i) Ground floor only
R
R
NR
R
NR
R
R
NR
R
50000
10 000
(see Note 20)
450
ii) Ground plus
R
R
NR
R
NR
R
R
NR
R
75 000
10000
(see Note 20)
450
one floor
Table 23 — Concluded
(l)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(ID
(12)
(13)
(14)
(15)
r
©
i
o
©
o
iii) More than ground R R
plus one floor
HAZARDOUS BUILDINGS (J) (see Note 17)
1) Up to 15 m in height
i) Single Storey R R
Building
NR
NR
NR
100 000
10 000
(see Note 20)
450
ii)
More than one floor
building but not
exceeding 15 m
NR
NR
NR
NR
Minimum
4 h fire
fighting
requirements
Minimum
4 h fire
fighting
requirements
NR
50 000
(see? Note 18)
(see Note 18)
NR
900
R — Required
NR — Not Required
NOTES
1 Buildings abovelS m in height not to be permitted for occupancies A-l and A-2.
2 Required to be installed in basement if area of basement exceeds 200 m 2 .
3 Required to be provided if basement area exceeds 200 m 2 .
4 Additional value given in parenthesis shall be added if basement area exceeds 200 m 2 .
5 Required to be provided for buildings with more than two storeys (Ground + One).
6 As per the requirement of local authority Dry Riser may be used in hilly areas, industrial areas or as required.
7 Required to be provided for buildings with height above 15 m.
8 To be installed in basement. If basement provided is used for car parking and area thereof exceeds 750 m 2 then the sprinklers shall be fed water from both underground static water storage tank and
terrace tank.
9 Required to be provided for buildings with more than one storey.
10 To be installed in entire building.
11 To be installed in all floors at appropriate places and in consultation with local fire authorities.
12 Buildings above 30 m in height not to be permitted for Group B, Group C, Group D and Group F occupancies.
13 All underground shopping areas should be fully air-conditioned,
14 The requirements given in this table for Group G Industrial Buildings are for small scale industry units. For other industries the requirements will have to be worked out on the basis of relevant Indian
Standards and also in consultation with the local fire authorities.
15 Buildings above 18 m in height not to be permitted for G-l and G-2 occupancies.
16 Buildings above 15 m in height not to be permitted for G-3 occupancies.
17 Buildings above 15 m in height not to be permitted for Group H and Group J occupancies.
J? 18 Pump capacity shall be based on the covered area of the building.
2 19 One electric and one diesel pump of capacity 1 620 1/min and one electric pump of capacity 180 1/min (see Fig, .4).
■* 20 One electric and one diesel pump of capacity 2 280 1/min and one electric pump of capacity 180 1/min (see Fig. 4).
3 21 Two electric and one diesel pump of capacity 2 280 1/min and one electric pump of capacity 180 1/min (see Fig. 5).
^ 22 Two electric and one diesel pump of capacity 2 850 1/min and one electric pump of capacity 180 1/min (see Fig. 5).
% 23 For buildings 45 m and above, the entire quantity of water for fire fighting purpose (as required in respective occupancy), if provided at the terrace level, the main pump qpgakjer pump, jockey pump
and common pump need not be provided, however one electric fire pump of 900 LPM capacity with automatic operation is required to be provided.
e
CM
ELEVATIONALVIEW
GR.FL
FIRE& SPRINKLER
• FROM FIRE PLANT ROOM
-SPRINKLER DRAIN PIPE
TO FIRE TANK
TO FIRE &
SPRINKLER SYSTEM «*-
(INTERNAL)
TO EXTERNAL FIRE
HYDRANT
(EXTERNAL)
**
«M-
F-2
FIRE PUMP ROOM
LEGEND :-
F-1 ELECTRICAL FIRE
PUMP
F-2 DIESEL DRIVEN FIRE
PUMP
F-3 JOCKEYPUMP
PV PRESSURE VESSEL
M FH FIRE HYDRANT
Q— VALVE
-R FLEXIBLE CONNECTION
NONRETURN VALVE
WIRING TO FAP
VALVE
€ JOINT
WITCH
TO SPRINKLERS SYSTEM
VALVE
TEST VALVE
SIGHT GLASS
DETAIL-'*
FIRE WATER TANK-1
FIRE WATER TANK-2
PLAN
Fig. 4 Typical System of Pumping with One Electric and
One Diesel Fire Pump
44
NATIONAL BUILDING CODE OF INDIA
ELEVATIONAL VIEW
FRFL,
i^H^^;ViW;v^i^::ja »
1 — *— i — i — T
SP
ORFL.
tFROM
"FIRE PLANT ROOM
-SPRINKLER RISER FROM
FIRE PLANT ROOM
"SPRINKLER DRAIN
PIPE TO FIRE TANK
LEGEND:-
F-1 DIESEL DRIVEN FIRE PUMP
F-2 EL. HYDRANT FIRE PUMP
F-3 JOCKEY PUMP
F-4 EL. SPRINKLER PUMP
PV PRESSURE VESSEL
FH FIRE HYDRANT
— M VALVE
— O— FLEXIBLE CONNECTION
— R NONRETURN VALVE
WIRING TO FAP
I VALVE
iE JOINT
FLOW SWITCH
TO SPRINKLERS
SYSTEM
IN VALVE
TEST VALVE
SIGHT GLASS
UNION
DETAIL-'*
TO FIRE
SYSTEM
(INTERNAL)
TO EXTERNAL FIRE
HYDRANT (EXTERNAL)
TO SPRINKLER
SYSTEM -*
-*K-F«3-^)a-M—
*-
<*■
•w
F-1
F-2
F-3
F-4
-*h-F+CJ-^)e*»—
-M-
FIRE PUMP ROOM
FIRE WATER TANK-1
FIRE WATER TANK-2
PLAN
Fig. 5 Typical System of Pumping with Two Electric,
One Diesel Fire Pump
PART 4 FIRE AND LIFE SAFETY
45
5.1.3 In situations where one occupancy is provided
with all the required fire protection arrangements but
due to proximity of unprotected buildings around,
causing exposure hazard to the protected building, the
protected building walls facing the unprotected
building shall be made of the requisite fire resistance
rated materials or alternatively provided with water
curtain/drencher system which can be actuated, when
necessary.
5.1.4 First-aid fire fighting appliances shall be
provided and installed in accordance with good practice
[4(21)]. The fire fighting equipment and accessories
to be installed in buildings for use in fire fighting shall
be in accordance with the accepted standards contained
in [4(20)] and shall be maintained periodically so as
to ensure their perfect serviceability at all times.
5.1.5 In addition to wet riser or down-comer, first-aid
hose reels shall be installed on all the floors of buildings
of 15 m in height or more and shall be in accordance
with accepted standards [4(22)]. The first-aid hose reel
shall be connected directly to the riser/down-comer
main and diameter of the hose reel shall not be less
than 19 mm.
5.1.6 Static Water Storage Tanks
A satisfactory supply of water for the purpose of fire
fighting shall always be available in the form of
underground/terrace level static storage tank with
capacity specified for each building with arrangements
or replenishment by mains of alternative source of
supply at the rate of 1 000 1/min for underground static
tank. When this is not practicable, the capacity of static
storage tank(s) shall be increased proportionately in
consultation with the local fire brigade.
The static storage water supply required for the above
mentioned purpose shall entirely be accessible to the
fire engines of the local fire service. Provision of
suitable number of manholes shall be made available
for inspection, repairs, insertion of suction hose,
etc. The covering slab shall be able to withstand the
total vehicular load of 45 T equally divided as a four
point load when the slab forms a part of pathway/
driveway.
The domestic suction tank connected to the static water
storage tank shall have an overflow capable of
discharging 2 250 1/min to a visible drain point from
which by a separate conduit, the overflow shall be
conveyed to a storm water drain.
a) To prevent stagnation of water in the static
water storage tank, the suction tank of the
domestic water supply shall be fed only
through an overflow arrangement to maintain
the level therein at the minimum specified
capacity (see Fig. 6).
b) The static water storage tank shall be provided
with a fire brigade collecting head with 4
number 63 mm diameter (2 number 63 mm
diameter for pump with capacity 1 400 1/min)
instantaneous male inlets arranged in a valve
box at a suitable point at street level and
connected to the static tank by a suitable fixed
pipe not less than 150 mm in diameter to
discharge water into the tank when required
at the rate of 2 250 1/min, if tank is in the
basement or not approachable for the fire
engines.
5.1.7 Automatic Sprinklers
Automatic sprinklers shall be installed in:
a) basements used as car parks or storage
occupancy, if the area exceeds 200 m 2 ;
b) multi-level basements, covered upper floors
used as car parks, and for housing essential
services ancillary to a particular occupancy
or for storage occupancy, excluding any area
to be used for sub-station, A.C. plant and DG
set;
c) any room or other compartment of a building
exceeding 1 125 m 2 in area except as in (g)
(see Note 1), if so advised by local authority;
d) departmental stores or shops, if the aggregate
covered area exceeds 500 m 2 ;
e) all non-domestic floors of mixed occupancy
which constitute a hazard and are not provided
with staircases independent of the remainder
of the buildings;
f) godowns and warehouses, as considered
necessary;
g) on all floors of the buildings other than
residential and educational buildings, if the
height of the building exceeds 15 m (45 m in
case of group housing and apartments) (see
Note 1);
h) dressing room, scenery docks, stages and
stage basements of theatres;
j) in hotels, hospitals, industries low and
moderate hazard mercantile buildings of
height 15 m or above;
k) in hotels below 15 m, if covered area at each
floor is more than 1 000 m 2 ;
m) false ceiling voids exceeding 800 mm in
height (see Note 2); and
n) canteen provided in upper floors of D-l
and D-2 occupancies shall be sprinklered.
NOTES
1 It is desirable that all high rise buildings should be fully
sprinklered irrespective of their height and occupancy. If
46
NATIONAL BUILDING CODE OF INDIA
4 Nos. 63 mm
INLET -
VALVE BOX
/ CABINET
PRIME
MOVER
TOWN MAIN
SUPPLY
0150 mm
MANHOLE
GL
FIRE
PUMP
{
SUCTION
FIRE
FIGHTING
TANK
2
as i— ~ — : ^v\v
SLOPJE
jD
OVERFLOW
AND VENT
GL
-SEPARATION
WALL
-DOMESTIC WATER
SUPPLY TANK (OTHER
THAN DRINKING WATER)
FOOT VALVES
6A WITH NEGATIVE SUCTION
DOMESTIC WATER
SUPPLY TANK (OTHER
THAN DRINKING WATER) -
SEPARATION WALL -
TO DOMESTIC
X PUMP SUCTION
SLUICE
VALVE -
VALVE BOX
/CABINET
OVERFLOW
AND VENT
4 Nos. 63 1
F. B. INLET
3B WITH POSITIVE SUCTION
Fig. 6 Typical Arrangement for Providing Combind Fire Fighting and
Domestic Water Storage Tank
PART 4 FIRE AND LIFE SAFETY
47
Table 24 Size of Rising Mains/Risers
(Clause 5.1.2)
Size of the Mains
Type of Building
(1)
(2)
100 mm as single outlet
landing valves
1.
Residential buildings (A)
i) l) Lodging or rooming houses
ii) Dormitories
iii) One or two family private dwellings
iv) Apartment houses (flats)
v) With shopping area not exceeding
500 m 2
vi) Hotels
-do-
2.
Educational buildings (B)
-do-
3.
Institutional buildings (C)
Height of Building
(3)
-do-
-do-
-do-
-do-
-do-
-do-
-do-
150 mm with twin outlet
landing valves
-do-
-do-
-do-
-do-
i) For hospitals and sanitorium
ii) For custodial institutions and mental
institutions
4. Assembly buildings (D)
5. Business buildings (E)
6. Mercantile buildings (F)
7. Industrial buildings (G)
8. All buildings classified under 1 (i) to (iv)
9. All buildings classified under 5 above with
shopping area exceeding 500 m 2
10. All buildings classified under 1 (v) above
11. Hotels
12; All buildings classified under 2 and 3 above
13. All buildings classified under 5 above
14. All storage buildings (H)
15. All Hazardous buildings (J)
15 m or above and not exceeding 45 m
Less than 15 m
15 m or above in height but not exceeding 30 m
and area not exceeding 600 m 2 per floor
15 m or above but not exceeding 30 m
15 m or above but not exceeding 30 m
15 m or above but not exceeding 30 m
15 m or above but not exceeding 30 m and total floor
area not exceeding 500 m 2 /floor (above 30 m, not to
be permitted)
15 m or above but not exceeding 30 m
15 m or above but not exceeding 30 m
(above 30 m, not to be permitted)
15 m or above but not exceeding 18 m
Above 45 m
Above 15 m
Above 30 m and area exceeding 500 m 2
Above 30 m
AtemMm
Above 30 m
Above 10 m but not exceeding 15 m
Above 10 m but not exceeding 15 m
l) Buildings above 15 m in height not permitted in case of high hazard industrial buildings.
selective sprinklering is adopted, there is a real danger of a fire
starting on one of the lower unsprinklered floors gathering
momentum, spreading upwards from floor to floor through the
unsprinklered floor and reaching the first sprinklered floor as
a fully developed fire. In such an event, the sprinklers can be
rendered useless or ineffective.
2 Use of false ceiling voids for storage or as return air plenums
should be discouraged,
3 For areas having very high ceiling height and other special
function areas, where automatic sprinklers cannot be provided,
appropriate sprinklers/provisions shall be provided in
consultation with local fire authorities.
5.1.8 Automatic High Velocity Water Spray or
Emulsifying System
Automatic high velocity water spray or emulsifying
system shall be provided for protection of indoor oil-
cooled transformers as applicable in accordance
with C-1.16 and good practice [4(23)].
5.1.9 Fixed Foam Installation
Fixed foam generating system shall be provided for
protection of oil storage area for boilers with its
ancillary storage of furnace oils in basement. Fixed
foam installations can be low, medium or high
expansion types, which can cover fire risks in oil
storage areas generally. High expansion foams are used
for cable tunnels and other confined areas.
5.1.10 Carbon Dioxide Fire Extinguishing System
Fixed carbon dioxide fire extinguishing installation
shall be provided in accordance with good practice
48
NATIONAL BUILDING CODE OF INDIA
[4(24)] on premises where water or foam cannot be
used for fire extinguishing because of the special nature
of the contents of the buildings/areas to be protected.
For some special fire risk/essential applications, carbon
dioxide may not be suitable and it may be necessary to
provide BCF (Bromochlorodifluoromethane) — Halon
1211 or BTM (Bromochlorotrifluoromethane) —
Halon 1301 or some other identified substitutes.
However, the use of halons shall be discouraged, as
halons are ozone depleting substances (ODS) and their
use is being phased out throughout the world.
5.1.11 Fire fighting equipment shall be suitably
located and clearly marked by luminous signs.
NOTE — This provision shall not apply to occupancies A-2
and A-4 less than 15 m in height.
5.2 Fire Detection/Extinguishing System
In buildings of such size, arrangement or occupancy
that a fire may not itself provide adequate warning to
occupants, automatic fire detection and alarm facilities
shall be provided, where necessary, to warn occupants
early of the existence of fire, so that they may escape,
or to facilitate the orderly conduct of fire exit drills.
5.2.1 The fire detection and extinguishing system shall
be in accordance with accepted standards [4(18)].
Guidelines for selection of various types of fire
detectors for different occupancies shall be in
accordance with good practice [4(19)]. Addressable
analog fire detection system shall be preferred.
5.2.2 The requirements of fire detection and alarm
systems are also covered for each occupancy in 6.1
to 6.9; and for high rise buildings (15 m or more in
height) in Annex C.
5.3 Fire Extinguisher/Extinguishing System Using
Halon Alternatives
Provisions for certain fire extinguishers and extinguishing
systems for fire protection which may be used as halon
alternatives, shall be in accordance in [4(25)].
6 ADDITIONAL OCCUPANCY-WISE
REQUIREMENTS
6.1 Requirements of Residential Buildings (Group A)
6.1.1 In addition to the general requirements for the
type of construction and occupancy group specified
in 3.4 and the exit requirements given in 4, the
requirements 6.1.2 to 6.1.4.10 shall be complied with.
The capacity of any open mezzanine or balcony shall
be added to the capacity of the floor below for the
purpose of determining exit capacity.
6.1.2 Fire Detection/Extinguishing System
The requirements for occupancy sub-divisions A-l to
A-5 as specified in Table 23 and Annex C (for High
Rise Buildings) shall apply.
6.1.3 Exit Facilities
The capacity of any open mezzanine or balcony shall
be added to the capacity of the floor for the purpose of
determining the exit capacity.
6.1.3.1 In addition to requirements specified for
occupancy sub-division A-2, the following shall be
provided for occupancy sub-division A-l:
Every sleeping room above the street floor shall
have access to two separate means of exits, 'at least
one of which shall consist of an enclosed interior
stairway, or a fire escape or horizontal exit all so
arranged as to provide a safe path of travel to the
outside of the building without traversing any
corridor or space exposed to an unprotected
vertical opening.
6.1.3.2 For occupancy sub-division A-2 of more than
two rooms, every occupied room, excluding areas used
solely for storage shall have at least two means of exits,
at least one of which shall be a door or a stairway
providing a means of un-obstructed travel to the outside
of the building or street or grade level. No room or
space shall be occupied which is accessible only by a
ladder, folding stairs or through a trap door.
Further the following provisions shall be made:
All locking devices, which would impede or
prohibit exit, such as chain type bolts, limited
opening sliding type locks and burglar locks,
which are not dis-engaged easily by quick-
releasing catches, shall be prohibited. All closet
door latches shall be such that even children can
open the doors from inside. All bathroom door
locks or fasteners shall be designed to permit the
opening of the locked or closed door from the
outside in an emergency without the use of a
special key.
6.1.3.3 For occupancy sub-division A-3, the following
provisions shall apply:
All dormitories shall lave exits so arranged that
from any sleeping room or open dormitory
sleeping area, there shall be access to two separate
and distinct exits in different directions with no
common path of travel unless the room or space
is subject to occupancy by not more than 10
persons and has a door opening directly to the
outside of the building at street or grade level, or
to an outside stairway in which case one means of
exit may be accepted.
6.1.3.4 For occupancy sub-division A-4, the following
provisions shall apply:
PART 4 FIRE AND LIFE SAFETY
49
a) Every individual living unit covered by
occupancy sub-division A-4 shall comply
with the requirement for occupancy sub-
division A-2 in respect of exits.
b) Every living unit shall have access to at least
two separate exits, which are remote from
each other and are reached by travel in
different directions, except that a common
path of travel may be permitted for the first
6 m (that is a dead end corridor up to 6 m long
may be permitted) provided that single exit
may be permitted under any of the conditions
given under (c).
c) Any part of building lower than the grade
level shall have direct accessibility from
outside.
d) At least half of required exits shall discharge
direct to the outside of the buildings; any
other exit shall be the same as required for
hotels.
6.1.3.5 For occupancy sub-divisions A-5 and A-6, the
following provisions shall apply:
a) Not less than two exits, as remote from each
other as practicable, shall be accessible from
every floor, including basements occupied for
hotel purpose, except as a single exit as
permitted in (b) below. Exits and ways of
access thereto shall be so arranged that they
are accessible in at least two different
directions from every point in any open area,
or from any room door.
b) Any room or section with an outside door at
street or grade level may have such outside
door as a single exit, provided no part of the
room or area is more than 15 m from the door
measured along the natural path of travel.
c) Provision of panic bars shall be provided in
the exits.
6.1.3.5.1 Where stairways or other exits serve two or
more upper floors, the same stairway or other exit
required to serve any one upper floor may also serve
other upper floors, except that no inside open stairway
or ramp may serve as a required egress facility from
more than one floor [see good practice 4(26)].
6.1.3.6 Basement Exits
a) Basements occupied for hotel purposes shall
have exits arranged in accordance with 6.1.3.5.
b) Basement exits shall be sufficient to provide
for the capacity of the basement as determined
in accordance with 6.1.1. In no case shall there
be less than two independent basement exits.
c) Basement or sub-basements not open to the
public and used only for heating equipment,
storage and service operations (other than
kitchens, which are considered part of the hotel
occupancy) shall have exits appropriate to the
actual occupancy, in accordance with other
applicable provisions of the Code, or in case
of mixed occupancy where there may be doubt
as to which other section is applicable, such
basements shall have exits determined on the
basis of lesser exit capacity.
6.1.4 Additional Precautions
6.1.4.1 Flammable liquids for household purposes
shall be kept in tightly stoppered or sealed containers.
For the limits of quantities of flammable liquids to be
allowed in various occupancies, reference may be made
to appropriate regulations.
6.1.4.2 No stove or combustion heater shall be located
directly under or immediately at the foot of stairs or
otherwise so located as to block escape in case of
malfunctioning of the stove or heater.
6.1.4.3 All kitchen exhaust fans, where provided, shall
be fixed to an outside wall or to a duct of non-
combustible material, which leads directly to the
outside. The ducts must not pass through areas having
combustible materials.
6.1.4.4 All wiring shall be done in accordance with
Part 8 'Building Services, Section 2 Electrical
Installations', good practice [4(10)] and National
Electric Code.
6.1.4.5 Where television is installed, all outdoor
antennae shall be properly grounded and protected
from lightning (see Part 8 'Building Services, Section 2
Electrical Installations').
6.1.4.6 Doors leading to rooms in which flammable
liquids are stored or used shall be as in 4.7. Such
assembly shall be self-closing and shall be posted with
a sign on each side of the door in 25 mm high block
letters stating — 'FIREDOOR — KEEP CLOSED'.
6.1.4.7 Where a boiler room is provided or a central
heating plant is installeq\ which uses solid or liquid
fuel, it shall be separated j&rom rest of the building by a
separation wall with all openings protected as in 3.4.7
and 3.4.8.
6.1.4.8 Rooms containing high pressure boilers,
refrigerating machinery, transformers or other service
equipment subject to possible explosion shall not be
located directly under or adjacent to exits. All such
rooms shall be effectively cut off from other parts of
the building and shall be provided with adequate vents
to the outside air.
6.1.4.9 All rooms or areas of high hazard in additions
to those herein before mentioned, shall be segregated
50
NATIONAL BUILDING CODE OF INDIA
or shall be protected as may be directed by the
enforcing Authority where, in the opinion of the
enforcing Authority, fire, explosion or smoke there
from is likely to interfere with safe egress from the
building.
6.1.4.10 For detailed information regarding fire safety
requirements for hazardous petroleum products,
reference may be made to the Petroleum Act, 1934
and the Rules thereof.
6.2 Requirements of Educational Buildings
(Group B)
6.2.1 In addition to the general requirements specified
in 3.4 for the type of construction and occupancy group
and the exit requirements given in 4, the requirements
given in 6.2.2 to 6.2.6.3 shall be complied with.
6.2.2 Buildings intended for educational occupancy
shall not be used for any hazardous occupancy.
6.2.3 Fire Detection/Extinguishing System
The requirements for occupancy sub-divisions B-l and
B-2 as specified in Table 23 and Annex C (for High
Rise Buildings) shall apply.
6.2.4 Exit Facilities
The capacity of any open mezzanine or balcony shall
be added to the capacity of the floor for the purpose of
determining the exit capacity.
In addition to the provisions in 4, the following shall
be provided:
6.2.4.1 Exits, in accordance with 4 shall be so arranged
that at least two separate exits are available in every
floor area. Exits shall be as remote from each other as
practicable and so arranged that there are no pockets
or dead ends of appreciable size in which occupants
may be trapped.
6.2.4.2 Every room with a capacity of over 45 persons
in area shall have at least two doorways.
6.2.4.3 Exterior doors shall be operated by panic bars
or some other panic hardware device, except that doors
leading from classrooms directly to the outside may
be equipped with the same type of lock as is used on
classroom doors leading to corridor, with no provision
whatsoever for locking against egress from the
classroom.
6.2.5 Additional Precautions
6.2.5.1 Storage of volatile flammable liquids shall be
prohibited and the handling of such liquids shall be
restricted to science laboratories only.
6.2.5.2 Each building shall be provided with an
approved outside gas shut-off valve conspicuously
marked. The detailed requirements regarding safe use
of gas shall be as specified in Part 9 'Plumbing
Services, Section 3 Gas Supply'.
6.2.5.3 All exterior openings in a boiler room or rooms
containing central heating equipment, if located below
opening in another storey or if less than 3 m from other
doors or windows of the same building, shall be
protected by a fire assembly as in 3.4.8. Such
assemblies shall be fixed, automatic or self-closing.
Provisions of 6.1.4.7 shall also apply to this group of
occupancy.
6.2.6 Exception and Deviation
6.2.6.1 Gymnasiums, indoor stadiums and similar
occupancies may have floors/running tracks of wood,
cinder, synthetic or unprotected steel or iron.
6.2.6.2 In gymnasiums and in multi-purpose school
rooms having an area not greater than 300 m\ 25 mm
nominal tight tongue-and-grooved or 20 mm plywood
wall covering may be used in the inner side in lieu of
fire-resistant plaster.
6.2.6.3 A building, which will have only the first floor
and is accessible to not more than 20 pupils at any
time, may be used for school purposes with the
following exceptions:
a) Exterior walls or parts of walls which are less
than 900 mm from adjacent property lines
shall have no openings therein.
b) Classrooms may have only one exit not less
than 900 mm wide.
6.3 Requirements of Institutional Buildings
(Group C)
6.3.1 In addition to the general requirements specified
in 3.4 for the type of construction and occupancy group
and the exit requirements given in 4, the requirements
given in 6.3.2 to 6.3.5 shall be complied with.
6.3.2 Fire Detection/Extinguishing System
The requirements for occupancy sub-divisions as
specified in Table 23 and Annex C (for High Rise
Buildings) shall apply.
6.3.3 Exit Facilities
In addition to the provisions of 4, the following
requirements shall be complied with.
6.3.3.1 In buildings or sections occupied by bed-
ridden patients where the floor area is over 280 m 2 ,
facilities shall be provided to move patients in hospital
beds to the other side of a smoke barrier from any part
of such building or section not directly served by
approved horizontal exits or exits from the first floor
(floor 2) of a building to the outside.
PART 4 FIRE AND LIFE SAFETY
51
6.3.3.2 Not less than two exits of one or more of the
following types shall be provided for every floor,
including basement, of every building or section:
a) Doors leading directly outside the building;
b) Stairways;
c) Ramps;
d) Horizontal exits; and
e) Fire tower.
6.3.3.3 All required exits that serve as egress from
hospital or infirmary sections shall be not less than
2 m in clear width including patient bedroom doors to
permit transportation of patients on beds, litters, or
mattresses. The minimum width of corridors serving
patients bedrooms in buildings shall be 2 400 mm. For
detailed information on recommendations for buildings
and facilities for the physically handicapped, reference
may be made to good practice [4(27)].
6.3.3.4 Elevators constitute a desirable supplementary
facility, but are not counted as required exits. Patient
lifts shall also be provided with enough room for
transporting a stretcher trolley.
6.3.3.5 Any area exceeding 500 m 2 shall be divided
into compartments by fire resistant walls.
6.3.3.6 Doors in fire resistant walls shall be so installed
that these may normally be kept in open position, but
will close automatically. Corridor door openings in
smoke barriers shall be not less than 2 000 mm in width.
Provision shall also be made for double swing single/
double leaf type door.
6.3.3.7 Exits and other features for penal and mental
institutions, and custodial institutions shall be the same
as specified for hospitals, in so far as applicable.
Reliable means shall be provided to permit the prompt
release of inmates from any locked section in case of
fire or other emergency.
6.3.3.8 Wherever any inmates are confined in any locked
rooms or spaces, adequate guards or other personnel shall
be continuously on duty or immediately available to
provide for release of inmates or for such other action as
may be indicated in case of fire or other emergency.
6.3.3.9 No building constructed in whole or in part of
combustible materials shall be used to confine inmates
in cells or sleeping quarters, unless automatic sprinkler
protection is provided.
6.3.3.10 All buildings or sections of buildings in penal
and mental institutions used for manufacturing, storage
or office purposes shall have exits in accordance with
the provisions of the Code for those occupancies.
6.3.4 Additional Precautions
6.3.4.1 No combustible material of any kind shall be
stored or used in any building or section thereof used
for institutional occupancy, except as necessary to
normal occupancy and use of the building.
6.3.4.2 Bare minimum quantities of flammable
material such as chloroform, ethyl alcohol, spirit, etc
shall be allowed to be stored and handled. The handling
of such liquids shall not be permitted by un-authorized
persons. Bulk storage of these items, will be governed
by relevant rules and safe practices.
6.3.5 Exceptions and Deviations
It is recognized that in institutions or part of buildings
housing various types of psychiatric patients, or used
as penal and mental institutions, it is necessary to
maintain locked doors and barred windows; and to such
extent the necessary provision in other sections of the
Code requiring the keeping of exits unlocked may be
waived. It is also recognized that certain type of
psychiatric patients are not capable of seeking safety
without adequate guidance. In buildings where this
situation prevails, reliable means for the rapid release
of occupants shall be provided, such as remote control
of locks, or by keying all locks to keys commonly used
by attendants.
6.4 Requirements of Assembly Buildings (Group D)
6.4.1 In addition to the general requirements specified
in 3.4 for type of construction and occupancy group
and the exit requirements given in 4, the requirements
given in 6.4.2 to 6.4.8.9 shall be complied with.
6.4.2 Mixed Occupancy
Places of assembly in buildings of other occupancy,
such as ballrooms in hotels, restaurants in stores and
assembly rooms in schools, shall be so located,
separated or protected as to avoid any undue danger to
the occupants of the place of assembly from a fire
originating in the other occupancy or smoke therefrom.
6.4.3 Fire Detection/Extinguishing System
The requirements for occupancy sub-divisions D-l to
D-5 as specified in Tible 23 and Annex C (for High
Rise Buildings) shall apply.
NOTE — Canteens shall not be provided in basements. If
provided in the upper floors, it shall be sprinklered.
6.4.4 Exit Facilities
6.4.4.1 Every place of assembly, every tier or balcony,
and every individual room used as a place of assembly
shall have exits sufficient to provide for the total
capacity thereof as determined in accordance with 4.
Door width for assembly buildings shall not be less
than 2 000 mm.
a) Every place of assembly of sub-division D-l
52
NATIONAL BUILDING CODE OF INDIA
shall have at least four separate exits as remote
from each other as practicable,
b) Every place of assembly of sub-division
D-2, shall have at least two separate exits as
remote from each other as practicable and if
of capacity over 600 at least three exits shall
be provided with each exit not less than of
2 000 mm width.
6.4.4.2 Clear aisles not less than 1.2 m in width shall
be formed at right angles to the line of seating in such
number and manner that no seat shall be more than seven
seats away from an aisle. Rows of seats opening on to
an aisle at one end only shall have not more than seven
seats. Under the conditions, where all these aisles do
not directly meet the exit doors, cross-aisles shall be
provided parallel to the line of seating so as to provide
direct access to the exit, provided that not less than one
cross aisle for every 10 rows shall be required. The width
of cross-aisles shall be minimum of 1 m. Steps shall not
be placed in aisles to overcome differences in levels,
unless the gradient exceeds 1 in 10.
6.4.4.3 The fascia of boxes, balconies and galleries
shall have substantial railings not less than 1 000 mm
high above the floor. The railings at the end of aisles
extending to the fascia shall be not less than 1 100 mm
high for the width of the aisle or 1 200 mm high at the
foot of steps.
6.4.4.4 Cross-aisles except where the backs of seats
on the front of the aisle project 600 mm or more above
the floor of the aisle shall be provided with railings
not less than 900 mm high.
6.4.4.5 No turnstiles or other devices to restrict the
movement of persons shall be installed in any place of
assembly in such a manner as to interfere in any way
with the required exit facilities.
6.4.4.6 In theatres and similar places of public
assembly where persons are admitted to the building
at a time when seats are not available for them and are
allowed to wait in a lobby or similar space until seats
are available, such use of lobby or similar space shall
not encroach upon the required clear width of exits.
Such waiting shall be restricted to areas separated from
the required exit ways by substantial permanent
partitions or fixed rigid railing not less than 105 cm
high. Exits shall be provided for such waiting spaces
on the basis o*f one person for each 0.3 m 2 of waiting
space area. Such exits shall be in addition to the exits
specified for the main auditorium area and shall
conform in construction and arrangement to the general
rules of exits given above.
6.4.4.7 No display or exhibit shall be so installed or
operated as to interfere in any way with access to any
required exit, or with any required exit sign.
All displays or exhibits of combustible material or
construction and all booths and temporary construction
in connection therewith shall be so limited in
combustibility or protected as to avoid any undue
hazard of fire which might endanger occupants before
they have opportunity to use the available exits, as
determined by the authority.
6.4.4.8 Places of assembly in buildings of other
occupancy may use exits common to the place of
assembly and the other occupancy, provided the
assembly area and the other occupancy are considered
separately, and each has exits sufficient to meet the
requirements of the Code.
6.4.4.9 Exits shall be sufficient for simultaneous
occupancy of both the places of assembly and other
parts of the building, unless the Authority determines
that the conditions are such that simultaneous
occupancy will not occur.
6.4.4.10 For any place of assembly under sub-division
D- 1 , at least half the required means of exits shall lead
directly outdoors or through exit ways completely
separated from exits serving other parts of the building.
6.4.4.11 For detailed information regarding cinema
buildings, reference may be made to good practice
[4(28)].
6.4.5 Lighting
No open flame lighting devices shall be used in any
place of assembly, except in the following cases:
a) Where necessary for ceremonial purposes, the
enforcing Authority may permit open flame
lighting under such restrictions as are
necessary to avoid danger of ignition of
combustible materials or injury to occupants.
b) Candles may be used on restaurant tables if
securely supported on non-combustible bases
and so located as to avoid danger of ignition
of combustible materials.
c) Open flame devices may be used on stages
where they are a necessary part of theatrical
performance, provided adequate precautions,
satisfactory to' the Authority are taken to
prevent ignition of combustible materials.
6.4.6 Additional Precautions
6.4.6.1 The decorations of places of assembly shall
be of non-flammable materials. Fabrics and papers used
for such purpose shall be treated with an effective
flame-retardant material. Stage settings made of
combustible materials shall likewise be treated with
fire retardant materials of Class 1 flame spread.
6.4.6.2 Seats in places of public assembly,
accommodating more than 300 persons, shall be
PART 4 FIRE AND LIFE SAFETY
53
securely fastened to the floor, except as permitted
in 6.4.6.3. All seats in balconies and galleries shall be
securely fastened to the floor, except that in nailed-in
enclosures, boxes with level floors and having not more
than 14 seats, the seats need not be fastened.
6.4.6.3 Chairs not secured to the floor may be
permitted in restaurants, night clubs and other
occupancies where the fastening of seats to the floor
may not be practicable, provided that in the area used
for seating, excluding dance floor, stage, etc, there shall
be not more than one seat for each 1 .4 m 2 of floor area
and adequate aisles to reach exits shall be maintained
at all times.
6.4.6.3.1 Rows of seats between aisles shall have not
more than 14 seats.
6.4.6.3.2 Rows of seats opening on to an aisle at one
end only shall have not more than 7 seats.
6.4.6.3.3 Seats without dividing arms shall have their
capacity determined by allowing 450 mm per person.
6.4.6.4 The spacing of rows of seats from back-to-
back shall be neither less than 850 mm nor less than
700 mm plus the sum of the thickness of the back and
inclination of the back. There shall be a space of not
less than 350 mm between the back of one seat and
the front of the seat immediately behind it as measured
between plumb lines.
6.4.6.5 Rooms containing high pressure boilers,
refrigerating machinery other than domestic
refrigerator type, large transformers or other service
equipments subject to possible explosion shall not be
located directly under or adjacent to the required exits.
All such rooms shall be effectively cut off from other
parts of the building and provided with adequate vents
to the outer air.
6.4.6.6 All rooms or areas used for storage of any
combustible materials or equipment, or for painting,
refinishing, repair or similar purposes shall be
effectively cut off from assembly areas or protected
with a standard system of automatic sprinklers. They
shall be located away from staircases.
6.4.6.7 Every stage equipped with fly galleries, grid
irons and rigging for movable theatre type scenery,
shall have a system of automatic sprinklers over and
under such stage areas or spaces and auxiliary spaces,
such as dressing rooms, store rooms and workshops,
and the proscenium opening shall be provided with a
fire- resisting curtain, capable of withstanding a lateral
pressure of 4 kN/m 2 over the entire area. The curtain
shall have an emergency closing device capable of
causing the curtain to close without the use of power
and when so closed, it shall be reasonably tight against
the passage of smoke.
6.4.6.8 The stage roof of every theatre using movable
scenery or having a motion picture screen of highly
combustible construction shall have a ventilator or
ventilators in or above it, openable from the stage floor
by hand and also opening by fusible links or some other
approved automatic heat/smoke actuated device, to
give a free opening equal to at least one-eighth the
area of the floor of the stage.
6.4.6.9 The proscenium wall of every theatre using
movable scenery of decorations shall have, exclusive
of the proscenium opening, not more than two openings
entering the stage, each not to exceed 2 m 2 and fitted
with self-closing fire resistant doors.
6.4.6.10 Every place of assembly in which projection
of motion pictures by light is made shall have the
projection apparatus enclosed in a fire-resisting fixed
booth in accordance with good practice [4(27)], except
that such booth shall not be required where no
nitrocellulose motion picture film is used.
6.4.6.11 Automatic smoke vents actuated by smoke
detectors shall be installed above the auditorium or
theatres, including motion picture houses, with vent
area equal to not less than 3 percent of the floor area
of the auditorium, including the sum of the floor areas
of all balconies, galleries, boxes and tiers. It may be
desirable to provide a large number of small vents
rather than a small number of large vents.
6.4.7 Exception and Deviation
6.4.7.1 Where boilers or central heating plants using
liquid or solid fuel are located at grade level, these
shall be separated from the remainder of the building
by a separating wall with openings protected as in 3.4.7
and 3.4.8.
6.4.7.2 Gymnasiums, indoor stadiums and similar
occupancies may have floors/running tracks of wood,
cinder, synthetic or un-protected steel or iron.
6.4.7.3 The underside of continuous steel deck grand
stands when erected outdoors need not be fire-protected
when occupied for public toilets.
6.4.8 Fire Protection and Fire Fighting System for
Metro Stations
6.4.8.1 Wet riser system
Main and diesel fire pump of 1 800 1/min capacity to
be provided to support 3 to 4 hydrants at a time. Jockey
pump capacity shall be 180 1/min. Where it is possible
to extend reliable DG supply to the fire pump room
without routing through the station building, the
provision of diesel pump can be dispensed with and
instead, two electric pumps may be provided out of
which at least one should have DG back-up. The jockey
pump should also have DG back-up.
54
NATIONAL BUILDING CODE OF INDIA
6.4.8.2 Internal hydrant
The internal hydrant is proposed to be provided with
2 number RRL hose pipes of 38 mm dia with 63 mm
standard instantaneous coupling along with associated
branch pipes and cabinet and a first aid hose reel of
25 mm dia, length 45 m and fitted with 6.5 mm
nozzle.
Two internal hydrants are proposed to be provided on
each platform in such a way so that most of the platform
is covered by hose. However, in case of necessity, the
hose pipes from other hose cabinets can be utilized for
extending the length of fire hose pipe for fire fighting,
if need be. At the concourse level minimum two
hydrants will be provided. In station where the
concourse is split into two halves at least one hydrant
is to be provided in each half of the concourse. Further,
in case the area is more than 2 000 m 2 , an additional
first aid hose-reel point shall be provided for every
additional 1 000 m 2 .
In addition, hydrants shall be provided in commercial
areas also.
One hydrant shall be provided at entry of each station
at ground floor for providing the coverage to the
parking area.
6.4.8.3 Sprinklers
Sprinklers are required to be provided only in the
commercial areas, if any, in the station. The commercial
areas will be segregated from the station area through
2 h fire rated walls and doors. Additional sprinkler
pumps are not required, as two pumps already provided
for hydrant system will take care of the sprinkler flow
requirements.
However, if such commercial areas in the premises of
stations are in isolated building separate from the
station building then the provision of sprinkler pump
and water tank capacities shall be as per this Code.
The water storage and pumps may however be
common.
6.4.8.4 Detectors
Detectors are required to be provided only in areas
where there are false ceiling and false floor and areas
of equipment rooms. Wherever there are false ceiling,
the detectors should be provided both above and below
false ceiling giving due consideration to depth of false
ceiling/flooring. However, in concourse, the detectors
below false ceiling may not be effective due to heights/
cross ventilation and therefore may not be provided.
In other areas, because of high heights and cross-
ventilations, detectors will not be effective and hence
therefore can be dispensed. A conventional detection
system will suffice at a normal station.
6.4.8.5 Manual call box
Manual call box should be provided at a central place
on each platform (near emergency plunger) and at least
two on the concourse, on each sidewall. When the
concourse in two halves there should be one manual
call box on each side.
6.4.8.6 Manual panel gas flooding
Electric panels should have provision of manual gas
flooding. Alternatively panels can be provided with
linear heat sensing tubes with C0 2 cylinder. This
required to be provided only in main power panels,
that is HT panel, main LT panel, main LT distribution
board and essential power panels and other such major
panels.
6.4.8.7 External area of the station
A 'two way/four way' fire brigade inlet to be provided
at ground level on each rising main for hydrants/
sprinkles.
The 'Draw Off Connection' shall be provided on the
underground tank for fire brigade.
6.4.8.8 Water tank capacity
Capacity of fire tanks at stations without any
commercial development (Beverage stall/ ATM/Florist/
Book stalls up to total 250 m 2 excluded) shall be 50 000
litres.
However, at stations having commercial development,
the fire tank capacity shall be 100 000 litres.
6.4.8.9 Portable fire extinguishers
For the purpose of standardization, the following
portable extinguishers are, recommended:
a) Water C0 2 type 9 litres
b) C0 2 fire extinguishers 4.5 kg
PART 4 FIRE AND LIFE SAFETY
55
They shall be provided in various areas as detailed hereunder:
SI
Item
Numbers and Location
No.
(1)
(2)
(3)
PLATFORM
1 . Internal Hydrants
2. Manual call box
3. Portable Extinguishers
CONCOURSE
1. Internal Hydrants
2. Additional first-aid reel point
3. Manual call box
4. Portable Extinguishers
5. Detectors
EQUIPMENT ROOM AREAS
1 . Internal Hydrants/first-aid reel
point
2. Manual call box
3. Portable Extinguishers
4. Detectors
5. Response Indicator
6. Panel gas flooding
EXTERNAL AREAS
1 . Hydrants
2. Two/four way fire brigade inlet
3. Fire brigade Draw-off connection
Two at each platform. The hydrants at two platforms may be
staggered for maximum coverage.
One on each platform preferably near emergency plunger.
One set of Water C0 2 and C0 2 type on each platform at a central
area.
Two at each concourse. When concourse is in two parts then each
part should have at least one hydrant.
Additional first-aid reel point for every additional 1 000 m 2 , if the
area is more than 2 000 m 2 . Similarly, if the concourse is in two parts
then additional first aid reel point for every additional
1 000 m 2 , if the area of the part is more than 1 000 m 2 .
Two at each concourse. When concourse is in two parts then each
part should have at least one.
Two sets at each concourse. When concourse is in two parts then
each part should have at least one set.
Above false ceiling where depth of false ceiling is greater than
800 mm. Required in commercial areas also.
The requirement shall get covered with platform/concourse.
Additional first-aid reel point may be provided, if required.
One at a central place. When the equipment rooms are in two/more
parts then each part should have one.
One set for each room.
Above and below false ceiling and below floor giving due
consideration to depth of false ceiling/floor.
To be provided.
To be provided for HT panel, main LT panel, main LT distribution
board and essential power panels and other such major panels.
One at ground floor at each entry to station near staircase/DG room.
To be provided for each riser/sprinkler riser.
To be provided on water tank.
6.5 Business Buildings (Group E)
6.5.1 In addition to the general requirements specified
in 3.4 for type of construction and occupancy group
and the exit requirements given in 4, the requirements
given in 6.5.2 to 6.5.5 shall be complied with.
6.5.2 Fire Detection/Extinguishing System
The requirements for occupancy sub-divisions as
specified in Table 23 and Annex C (for High Rise
Buildings) shall apply.
6.5.2.1 Occupancy sub-division E-l (except office
buildings)
Details of Fire Detection/Extinguishing
Occupancy System
E-l Automatic fire alarm system {good
practice [4(17)] and [4(18)], and
Table 23}.
56
NATIONAL BUILDING CODE OF INDIA
6.5.2.2 Occupancy sub-division E-2
Details of
Occupancy
a) Laboratory
with delicate
instruments
b) Solvent storage
and/or flammable
liquid
Fire Detection/Extinguishing
System
Fixed automatic C0 2 fire
extinguishing system or
automatic fire alarm system
{good practice [4( 1 8)] and
[4(19)], and Table 23}
Automatic foam installation
or automatic C0 2 fire
extinguishing system
6.5.2.3 Occupancy sub-division E-3
Details of
Occupancy
a) Area of computer
installations
b) Space under false
ceiling (floor)
c) Space above false
ceiling and below
false floor
d) Electrical switch
board
Fire Detection/Extinguishing
System
Automatic fire alarm system
{good practice [4(18)] and
[4(19)], and Table 23} any
suitable halon alternative fire
extinguishing system {see
5.3) or any other suitable fire
extinguishing installation
{see also [4(29)]}.
Automatic fire alarm system
{good practice [4(18)] and
[4(19)], and Table 23}
Automatic fire alarm system
{good practice [4(18)] and
[4(19)], and Table 23}
Automatic fire alarm system
{good practice [4(18)] and
[4(19)], and Table 23} and
C0 2 fire extinguishing
installation
6.5.2.4 Occupancy sub-division E-4
Details of
Occupancy
Telephone exchanges
Fire Detection/Extinguishing
System
Any suitable halon
alternative fire extinguishing
system (see 5.3) and/or
automatic sprinkler system as
per requirement (see also
Table 23)
6.5.2.5 Occupancy sub-division E-5
Details of
Occupancy
Broadcasting stations
Fire Detection/
Extinguishing System
Automatic fire alarm system
based on smoke detectors
and sprinkler system (see
also Table 23)
6.5.3 Exit Facilities
6.5.3.1 In the case of mezzanines or balconies open
to the floor below, or other unprotected vertical
openings between floors, the population of the
mezzanine or other subsidiary floor for level shall be
added to that of the main floor for the purpose of
determining the required exits, provided, however, that
in no case shall the total number of exit units be less
than that required if all vertical openings were enclosed.
6.5.3.2 Not less than two exits shall be provided for
every floor, including basements occupied for office
purposes or uses incidental thereto.
6.5.4 Additional Requirements
6.5.4.1 The handling and use of gasoline, fuel oil and
other flammable liquids shall not be permitted, unless
such use and handling complies with the appropriate
regulations.
6.5.4.2 Every boiler room or room containing a central
heating plant using solid or liquid fuel shall be
separated from the rest of the building by a separating
wall. Every boiler room or room containing a central
heating plant, which burns gas as a fuel shall be
adequately separated from the rest of the building.
6.5.5 Exception and Deviation
6.5.5.1 Basements used only for storage, heating, any
other service equipment shall conform to exit
requirements for Group H occupancies in all respects.
6.6 Requirements
(Group F)
of Mercantile Buildings
6.6.1 In addition to the general requirements specified
in 3.4 for type of construction and occupancy and the
exit requirements given in 4, the requirements given
in 6.6.1.1 to 6.6.5 shall be complied with.
6.6.1.1 Mixed occupancy
No dwelling unit shall have its sole means of exit
through any mercantile occupancy in the same building
except in the case of a single family unit where the
family operates the store.
6.6.2 Fire Detection/Extinguishing System
The requirements for occupancy sub-divisions F-l to
F-3 as specified in Table 23 and Annex C (for High
Rise Buildings) shall apply.
6.6.3 Exit Facilities
In addition to the provisions of 4, the following
requirements shall be complied with.
6.6.3.1 In the case of mezzanines or balconies open
to the floor below, or other un-protected vertical
openings between floors, the population or area of the
PART 4 FIRE AND LIFE SAFETY
57
mezzanine or other subsidiary floor level shall be added
to that of the main floor for the purpose of determining
the required exits, provided, however, that in no case
shall the total number of exit units be less than that
required if all vertical openings were enclosed.
6.6.3.2 At least two separate exits shall be accessible
from every part of every floor, including basements;
such exits shall be as remote from each other as
practicable and so arranged as to be reached by
different paths of travel in different directions, except
that a common path of travel may be permitted for the
first 15 m from any point.
6.6.4 Additional Precautions
6.6.4.1 Requirements specified in 6.5.4.1 shall be
applicable to all Group F occupancies also.
6.6.4.2 Hazardous areas of mercantile occupancies
shall be segregated or protected suitably.
6.6.4.3 In self-service stores, no check-out stand or
associated railings or barriers shall obstruct exits or
required aisles or approaches thereto.
6.6.4.4 Open-air mercantile operations, such as open-
air markets, gasoline filling stations, roadside stands
for the sale of a farm produce and other outdoor
mercantile operations shall be so arranged and
conducted as to maintain free and unobstructed ways
of travel at all times to permit prompt escape from any
point of danger in case of fire or other emergency, but
no dead-ends in which persons might be trapped due
to display stands, adjoining buildings, fences, vehicles
or other obstructions.
6.6.4.5 If mercantile operations are conducted in
roofed-over areas, these shall be treated as mercantile
buildings, provided canopies over individual small
stands to protect merchandise from the weather shall
not be constructed to constitute buildings for the
purpose of the Code.
6.6.5 Exception and Deviation
Any mercantile occupancy, where goods of a highly
hazardous nature are pre-dominant, shall be considered
under Group J occupancy for the purpose of the Code.
6.7 Requirements of Industrial Buildings (Group G)
6.7.1 In addition to the general requirements specified
in 3.4 for the type of construction and occupancy group
and the exit requirements given in 4, the requirements
given in 6.7.2 to 6.7.5 shall be complied with.
6.7.2 Fire Detection/Extinguishing System
The requirements for occupancy sub-divisions G- 1 to
G-3 as specified in Table 23 and Annex C (for High
Rise Buildings) shall apply.
6.7.3 Exit Facilities
In addition to the provisions of 4, the following
requirements shall be complied with.
6.7.3.1 Not less than two exits shall be provided for
every floor or section, including basements used for
industrial purposes or uses incidental thereto.
6.7.3.2 In buildings used for aircraft assembly or other
occupancy requiring undivided floor areas so large that
the distances from points within the area to the nearest
outside walls where exit doors could be provided are
in excess of 45 m, requirements for distance to exits
may be satisfied by providing stairs leading to exit
tunnels or to overhead passageways. In cases where
such arrangements are not practicable, the Authority
may, by special ruling, permit other exit arrangements
for one storey buildings with distances in excess of
the maximum distances specified in 4, if completely
automatic sprinkler protection is provided and if the
heights of ceiling curtain boards and roof ventilation
are such as to minimize the possibility that employees
will be overtaken by the spread of fire or smoke within
1 800 mm of the floor level before they have time to
reach exits, provided, however, that in no case may
the distance of travel to reach the nearest exit exceed
45 m where smoke venting is required as a condition
for permitting distances of travel to exits in excess of
the maximum otherwise allowed.
6.7.3.3 Additional precautions
a) In any room in which volatile flammable
substances are used or stored, no device
generating a glow or flame capable of igniting
flammable vapour shall be installed or used.
Such a room shall be provided with a suitably
designed exhaust ventilation system (see
Annex D). To ensure safety from fire due to
short circuit, faulty electrical connection or
some similar cause, proper care shall be taken
in designing electrical installations in such
room (see Part 8 'Building Services, Section 2
Electrical Installations').
b) The storage, use and handling of gasoline,
fuel oil and othej* flammable liquids shall
not be permitted in any Group G occupancy
unless it complies with regulations
pertaining to Petroleum Act, 1934 and Rules
thereunder.
c) Every boiler room or room below the first
floor containing a heating plant shall be
adequately separated from the rest of the
buildings.
d) For requirements regarding electrical
generating and distribution stations, reference
may be made to good practice [4(23)].
58
NATIONAL BUILDING CODE OF INDIA
6.7.3.4 Exception and deviation
a) Basements used only for storage, heating or
other service equipment, and not subject to
industrial occupancy, shall have exits in
accordance with the requirements of Group
H occupancies.
b) The following exceptions shall apply to
special purpose industrial occupancies:
1) Exits need be provided only for the
persons actually employed; spaces not
subject to human occupancy because of
the presence of machinery or equipment
may be excluded from consideration.
2) Where unprotected vertical openings are
necessary to manufacturing operations,
these may be permitted beyond the limits
specified for industrial occupancy,
provided every floor level has direct
access to one or more enclosed stairways
or other exits protected against obstruction
by any fire in the open areas connected
by the unprotected vertical openings or
smoke therefrom.
3) Industrial buildings of low and moderate
hazard are permitted only up to 18 m
height.
c) The following exceptions shall apply to high
hazard industrial occupancies:
1) Exits shall be so located that it will not
be necessary to travel more than 22.5 m
from any point to reach the nearest exit.
2) From every point in every floor area,
there shall be at least two exits accessible
in different directions; where floor areas
are divided into rooms, there shall be at
least two ways of escape from every
room, however small, except toilet
rooms, so located that the points of access
thereto are out of or suitably shielded
from areas of high hazard.
3) In addition to types of exits for upper
floors specified for Group G occupancies,
slide escapes may be used as required
exits for both new and existing
buildings.
4) All high hazard industrial occupancies
shall have automatic sprinkler protection
or such other protection as may be
appropriate to the particular hazard,
including explosion venting for any area
subject to explosion hazard, designed to
minimize danger to occupants in case of
fire or other emergency before they have
time to utilize exits to escape.
5) Industrial buildings of high hazard are
permitted only up to 15 m height.
6.7.4 For detailed information on fire safety of certain
individual (specific) industrial occupancies reference
may be made to good practice [4(39)].
6.7.5 Fire protection considerations for venting
industrial occupancies shall be as given in Annex D.
6.8 Requirements of Storage Buildings (Group H)
6.8.1 In addition to the general requirements
specified in 3.4 for type of construction and
occupancy group and the exit requirements given in 4,
the requirements given in 6.8.2 to 6.8.5 shall be
complied with.
6.8.2 Fire Detection/Extinguishing System
The requirements for occupancy group H, as specified
in Table 23 and Annex C (for High Rise Building)
shall apply.
NOTE — Automatic sprinklers are prohibited where water
reactive materials are kept. Instead automatic fire alarm system
coupled with suitable fire extinguishing systems shall be
installed.
6.8.3 Exit Facilities
In addition to the provisions of 4, the following
requirements shall also be complied with.
6.8.3.1 Every building or structure used for storage
and every section thereof considered separately, shall
have access to at least one exit so arranged and located
as to provide a suitable means of escape for any person
employed therein and in any room or space exceeding
1 400 m 2 gross area, or where more than 10 persons
may be normally present, at least two separate means
of exit shall be available, as remote from each other as
practicable.
6.8.3.2 Every storage area shall have access to at least
two means of exit, which can be readily opened. This
shall not be subject to locking so long as any persons
are inside and shall not depend on power operation.
6.8.3.3 The following special provisions shall apply
to parking garages of closed or open type, above or
below ground, but not to mechanical parking facilities
where automobiles are moved into and out of storage
mechanically which are not normally occupied by
persons and thus require no exit facilities. Where repair
operations are conducted, the exits shall comply with
the requirements of Group G occupancies in addition
to compliance with the following:
a) Where both parking and repair operations are
conducted in the same building, the entire
building shall comply with the requirements
for Group G occupancies, unless the parking
PART 4 FIRE AND LIFE SAFETY
59
and repair sections are effectively separated
by separation walls.
b) Every floor of every closed parking garage
shall have access to at least two separate
means of exit, so arranged that from any point
in the garage the paths of travel to the two
means of exit shall be in different directions,
except that a common path of travel may be
permitted for the first 15 m, from any point.
c) On the street floor, at least two separate exit
doors shall be provided, except that any
opening for the passage of automobiles may
serve as a means of exit, provided no door or
shutter is installed thereon. Street floor exits
in closed garages shall be so arranged that no
point in the area is more than 30 m from the
nearest exit, or 45 m in the case of garages
protected by automatic sprinklers, distance
being measured along the natural path of
travel.
d) On floors above the street, at least two means
of exit shall be provided, one of which shall
be an enclosed stairway. The other means of
egress may be a second exit of any of the
types, or in a ramp type garage with open
ramps not subject to closure, the ramp may
serve as the second means of exit.
e) Upper floor exits in closed garages shall be
so arranged that no point in the area shall be
more than 30 m from the nearest exit other
than a ramp on the same floor level or 45 m
in the case of garages protected by automatic
sprinklers.
f) On floors below the street (either basement
or outside underground garages) at least two
exits shall be provided, not counting any
automobile ramps, except that for garages
extending only one floor level below the
street, a ramp leading direct to the outside may
constitute one required means of exit. In
garages below street level, exits shall be so
arranged that no part of the area shall be more
than 30 m from the nearest stair exit.
g) If any gasoline pumps are located within any
closed parking garage, exits shall be so
located that travel away from the gasoline
pump in any direction shall lead to an exit;
with no dead-end in which occupants might
be trapped by fire or explosion at any
gasoline pump. Such exit shall lead to the
outside on the building on the same level, or
downstairs; no upward travel shall be
permitted unless direct outside exits are
available from that floor and any floor below
(as in the case of a basement garage where
the grade is one storey or more lower at the
rear than at the street).
6.8.3.4 Exits from aircraft hangers (storage or
servicing areas) shall be provided at intervals of not
more than 45 m on all exterior walls of aircraft hangers.
There shall be a minimum of two exits serving each
aircraft storage or servicing areas. Horizontal exits
through interior fire walls shall be provided at intervals
of not more than 30 m. 'Dwarf or 'smash' doors
accommodating aircraft may be used to comply with
these requirements. All doors designated as exits shall
be kept unlocked in the direction of exit travel while
the area is occupied.
6.8.3.5 Exits from mezzanine floors in aircraft storage
or servicing areas shall be so arranged that the
maximum travel to reach the nearest exits from any
point on the mezzanine shall not exceed 22.5 m. Such
exits shall lead directly to a properly enclosed stairwell
discharging directly to the exterior or to a suitably cut-
off area or to outside fire escape stairs.
6.8.3.6 The following special provisions shall apply
to grain elevators:
a) There shall be at least one stair tower from
basement to first floor and from the first floor
to the top floor of workhouse which is enclosed
in a dust-tight non-combustible shaft.
b) Non-combustible doors of self-closing type
shall be provided at each floor landing.
c) An exterior fire escape of the stair or basket
ladder type shall be provided from the roof
of the workshop to ground level or the roof
of an adjoining annexe with access from all
floors above the first.
d) An exterior fire escape of either the stair or
basket ladder type shall be provided from the
roof of each storage annexe to ground level.
6.8.4 Additional Precautions
Requirements specified in 6.7.3.3 shall apply to Group
H occupancies also.
6.8.5 Exceptions and Deviations
Every ,area used for the storage of hazardous
commodities shall have an exit within 22.5 m of any
point in the area where persons may be present or 35 m
where automatic sprinkler protection is provided.
6.9 Requirements of Buildings for Hazardous Uses
(Group J)
6.9.1 In addition to the general requirements specified
in 3.4 for type of construction and occupancy group
and the exit requirements given in 4, the requirements
given in 6.9.2 to 6.9.4 shall be complied with.
60
NATIONAL BUILDING CODE OF INDIA
6.9.2 Fire Detection/Extinguishing System
The requirements for occupancy Group J, as specified
in Table 23 and Annex C (for High Rise Building)
shall apply.
NOTE — Hazardous buildings shall have vapour detectors/
explosion suppression systems/automatic sprinklers, besides
hydrant system, wet risers and automatic fire alarm system
depending on the type of fire hazard involved.
6.9.3 Exit Facilities
Requirements specified in 4 and 6.7.3.4 (c) shall apply
to Group J occupancies also.
6.9.4 Additional Precautions
The following requirements shall apply to all Group J
occupancies, as applicable:
a) Each building where gas is employed for any
purpose shall be provided with an approved
outside gas shut-off valve conspicuously
marked. The detailed requirements regarding
safe use of gas shall be as specified in
Part 9 'Plumbing Services, Section 2 Gas
Supply'.
b) Each boiler room or room containing a
heating plant shall be separated from the rest
of the building by a separating wall.
c) In any room in which volatile flammable
substances are used or stored, no device
generating a spark, or glow flame capable of
igniting flammable vapour shall be installed
or permitted unless it is enclosed in a
flameproof enclosure.
d) The use, handling, storage and sale of
gasoline, fuel oil and other flammable liquids
snail not be permitted in Group J occupancies
unless such use, handling, storage and sale is
in accordance with appropriate legislation in
force.
e) All openings in exterior walls except wall
vents shall be protected by a fire stop
assembly as in 4 and they shall be fixed,
automatic or self-closing. Wall vents having
an area of not less than 100 cm 2 each shall be
placed in the exterior walls near the floor line,
not more than 1 800 mm apart horizontally.
Each building shall be provided with a power
driven fan exhaust system of ventilation
which shall be arranged and operated so as to
produce a complete change of air in each room
every 3 min.
f) Each machine in dry-cleaning establishments
which uses flammable liquid shall have an
adequate steam line or any other suitable
extinguishing agent directly connected to it,
so arranged as to have the agent automatically
released to the inside of each machine should
an explosion occur in the machine.
g) Equipment or machinery which generates or
emits combustible or explosive dust or fibres
shall be provided with an adequate dust
collecting and exhaust system.
PART 4 FIRE AND LIFE SAFETY
61
ANNEX A
(Clause 3.1.8)
CALORIFIC VALUES OF COMMON MATERIALS AND TYPICAL
VALUES OF FIRE LOAD DENSITY
A-l The calorific values of some common materials
are given in Table 25 for guidance.
Table 25 Calorific Values of Common Materials
Table 25 — Concluded
Material
(1)
Calorific Value Wood
(10 3 kj/kgr 1 ) l) Equivalent
(kg/kg)
(2) (3)
Solid Fuels
Anthracite
Bituminous Coal
Charcoal
Coke (average)
Peats
Sub-bituminous Coal
Woods (hard or softwood)
Hydrocarbons
Benzene
Butane
Ethane
Ethylene
Fuel Oil
Gas Oil
Hexane
Methane (natural gas)
Octane
Paraffin
Pentane
Propane
Propylene
Alcohols
Ethyl Alcohol
Methyl Alcohol
Propyl Alcohol
Polymers
Casein
Cellulose
Cellulose Acetate
Polyethylene
Polypropylene
Polystyrene
Polyvinylchloride
Polymethylmethacrylate
Polyurethane
Polyamide (nylon)
Polyester
Common Solids
Asphalt
Bitumen
Carbon
Cotton (Dry)
Flax
Furs and Skins
Hair (animal)
Leather
28,6
30,8
28;4
27:5
20$
22.0
17.6
39.6
47.1
49.1
47.7
41.6
42.9
44.9
52.8
45.3
39.6-44.0
46.0
47.3
46.2
28.4
21.1
31.9
23.1
16.5
17.8
48.4
48.4
41.8
20.9
24.6
35.2
22.0
22.0
38.3
33.4
32.1
15.8
14.3
18.7
20.9
17.6
1.66
1.75
1.61
1.56
1.19
1.25
1.00
2.25
2.68
2.79
2.71
2.36
2.44
2.55
3.00
2.58
2.3-2.5
2.61
2.69
2.63
1.61
1.20
1.81
1.31
0.94
1.01
2.75
2.75
2.38
1.19
1.40
2.00
1.25
1.25
2.13
1.90
1.83
0.90
0.81
1.06
1.19
1.00
(1)
(2)
(3)
Ozokerite (wax)
Paper (average)
Paraffin wax
Pitch
Rubber
Straw
Tallows
tan bait
lar (Diturninousj
Wool (raw)
Wool (scoured)
Foodstuffs
Barely
Bran
Bread
Butter
Cheese (Cheddar)
Commeal
Flour
Margarine
Oatmeal
Rice
Soyabean Flour
Sugar
Whole Wheat
Miscellaneous
Acetone
Acetaldehyde
Formaldehyde
Hydrogen
43.3
2.46
15.4
0.88
40.9
2.33
33.0
1.88
37.4
2.13
13.2
0.75
37.6
2.14
20.9
1.19
35.2
2.00
21.6
1.23
19,6
1.11
14.1
0.80
1L0
0.63
9J9
0.56
29.5
1.68
18.1
1.03
14.1
0.80
14.1
0,80
29.5
1.68
15.8
0.90
13.9
0.79
16.1
0.91
15.4
0.88
14.3
0.81
29.7
1.69
25.1
1.43
17.6
1.00
134,2
7.63
24.0
1.36
u 1 kJ is approximately equal to 1 Btu so the figures in the tables
are also equivalent to Btu/kg.
A-2 The typical values fire load density for arriving
at the classification of occupancy hazard is given in
Table 26 for guidance.
Table 26 Typical Values of Fire Load Density
SI Building Type
No.
Fire Load Density (Expressed
as Wood Equivalent
kg/m 2
(1) (2)
(3)
i) Residential (A-l and A-2)
25
ii) Residential (A-3 to A-5)
25
iii) Institutional and
25
Educational (B and C)
iv) Assembly (D)
25-50
v) Business (E)
25-50
vi) Mercantile (F)
Upto250
vii) industrial (G)
Up to 150
viii) Storage and Hazardous
(Hand J)
Up to 500
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NATIONAL BUILDING CODE OF INDIA
ANNEX B
(Clauses 3.1.8 and 3.1.11)
BROAD CLASSIFICATION OF INDUSTRIAL AND NON-INDUSTRIAL OCCUPANCIES
INTO DIFFERENT DEGREE OF HAZARD
B-l LOW HAZARD OCCUPANCIES
Abrasive manufacturing premises
Aerated water factories
Agarbatti manufacturing premises
Analytical and/or Q.C. Laboratories
Arecanut slicing and/or Betelnut factories
Asbestos steam packing and lagging manufacturers
Assembly buildings small (D-4 and D-5)
Battery charging and service stations
Battery manufacturing
Breweries
Brickworks
Canning factories
Cardamom factories
Cement factories and/or asbestos or concrete products
manufacturing premises
Ceramic factories, crockery, stoneware pipe
manufacturing
Clay works
Clock and watch manufacturing
Clubs
Coffee curing, roasting and grinding factories
Condensed milk factories, milk pasturising plants and
dairies
Confectionary manufacturing
Dwellings, lodges, dormitories, etc
Educational and research institutions
Electric lamps (incandescent and fluorescent) and T. V.
tube manufacturing
Electroplating works
Engineering workshops
Fruits and vegetables dehydrating and drying factories
Fruits products and condiment factories
Glass and glass fibre manufacturing
Godowns and warehouses (non-combustible goods)
Gold thread/gilding factories
Gum and/or glue and gelatine manufacturing
Ice candy and ice-cream and ice factories
Ink (excluding printing ink) factories
Mica products manufacturing
Office premises
Places of worship
Pottery works
Poultry farms
Residential buildings (A-l to A-4) (except hotels A-5)
Salt crushing factories/refineries stables
Sugar candy manufacturing
Sugar factories and refineries
Tanneries
Umbrella assembling factories
Vermicelli factories
Water treatment/filtration plants and water pump houses
Zinc/copper factories
B-2 MODERATE HAZARD OCCUPANCIES
Airport and other transportation terminal buildings
Aluminium factories
Assembly buildings (D-l to D-3)
Atta and cereal grinding
Bakeries and biscuit factories
Beedi factories
Bobbin factories
Book-binders, envelopes and paper bag manufacturing
Cable manufacturing
Camphor boiling
Candle works
Carbon paper/typewriter ribbon makers
Card board box manufacturing
Carpenters, wood wool and furniture makers
Carpet and durries factories
Cashewnut factories
Chemical manufacturers (using raw materials having
F.P > 23°C)
Cigar and cigarette factories
Coir factories
Cold storage premises
Computer installations
Cork products manufacturing (coir, carpets, rugs and
tobacco) (hides and skin presses)
Dry cleaning, dyeing and laundries
Electric sub-stations/distribution stations
PART 4 FIRE AND LIFE SAFETY
63
Electrical generating stations except under ground
powerhouses
Enamelware factories
Filler and wax paper manufacturing
Flour mills
Garment makers
Ghee factories (other than vegetable)
Godowns and warehouses (other than non-combustible
goods)
Grains and seed disintegrating or crushing
Grease manufacturing
Hosiery, lace, embroidery and thread
Hospitals including 'X'-ray and other diagonastic
clinics (institutional buildings)
Incandescent gas mantle manufacturers
Industrial gas manufacturing (only halogenated
hydrocarbons/inert gases)
Man-made yarn/fibre (except acrylic fibre/yarn)
Manure and fertilizer works (blending, mixing and
granulating only)
Mercantile occupancies (departmental stores, shopping
complex, etc)
Mineral oil blending and processing
Museums, archieves, record rooms
Oil and leather cloth factories
Open storage of flammable liquids (in drums, cans, etc)
Oxygen plants
Paper and cardboard mills (except raw material yard)
Piers, wharves, dockyards
Plastic goods manufacturing
Plywood/wood veneering factories
Printing press premises
Pulverizing and crushing mills
Residential apartments, hotels, cafes, restaurants
Rice mills
Rope works
Rubber goods manufacturing
Rubber tyres and tubes manufacturing
Shellac factories
Silk filiatures
Soaps and glycerine factories
Spray painting
Starch factories
Tea factories (including blending packing of tea)
Telephone exchanges, garages
Textile mills
Tobacco chewing and pan masala making
Tobacco re-drying factories
Woolen mills
B-3 HIGH HAZARD OCCUPANCIES
A)
Aircraft hangers
Aluminium/magnesium powder plants
Bitumanized paper/hessian cloth/tar felt manufacturing
Bulk storage of flammable liquids (tank farm, etc)
Celluloid goods making
Chemical manufacturers (where raw materials have a
F.P. < 23°C)
Cigarette filter manufacturing
Cinema films and T.V. production studios
Coal, coke and charcoal ball and briquettes making
Collieries, steel plants
Cotton seeds cleaning and delinting factories
Cotton waste factories
Distilleries
Duplicating/stencil paper making
Fire works manufacture
Foamed plastic and/or converting plants
Godowns of warehouses (combustible/hazardous
goods) (H)
Grass, hay, fodder and BHOOSA (chaff)
Hazardous occupancy buildings (J)
Industrial gas manufacturing (except halogenated
hydrocarbon gases/inert gases)
Industrial units (G-3 occupancies)
Jute mills and jute presses
Linoleum factories
Man-made fibres (only acrylic fibre/yarn making)
Match factories
Mattress and pillow makings (foam plastics)
Metal or tin printers (if more than 50 percent is
engineering, shift to oidinary hazard)
Oil mills
Oil extraction plants
Oil terminals/depots
Paints/Varnish factories
Paper and cardboard mills (only raw material yard)
Pressing factories
Printing ink making
Resin, lamp black and turpentine manufacture
Saw mills
64
NATIONAL BUILDING CODE OF INDIA
Surgical cotton manufacturing
Tarpaulin and canvas proofing factories
Turpentine and resin distilleries
Tyre retreading and resolving factories
Underground shopping complexes (F-3)
B)
Ammonia and urea synthesis plants
Explosive factories
LPG bottling plants
Petrochemical plants
Petroleum refineries
NOTE — In case of complexes having segregated plants with
varying degrees of hazards, the competent authority having
jurisdictions shall be consulted to decide the level of protections
to be provided.
ANNEX C
(Clauses 3.4.11.1, 4.18.2, 5.1.8, 5.2.2, 6.1.2, 6.2.3, 6.3.2, 6.4.3, 6.5.2, 6.6.2,
6.7.2, 6.8.2 and 6.9.2)
FIRE PROTECTION REQUIREMENTS FOR HIGH RISE BUILDINGS —
15 m IN HEIGHT OR ABOVE
C-0 GENERAL
In addition to the general provisions given in this Part,
the Authority may insist on suitable protection
measures (see C-l to C-ll) in abuilding 15 m in height
or above.
C-l CONSTRUCTION
C-l.l All materials of constructions in load bearing
elements, stairways and corridors and facades shall be
non-combustible.
C-1.2 The interior finish materials shall not have a flame
spreadability rating exceeding Class 1 (see 3.4.15.2).
C-1.3 The internal walls or staircase shall be of brick
or reinforced concrete with a minimum of 2 h fire
rating.
C-1.4 The staircase shall be ventilated to the
atmosphere at each landing and a vent at the top; the
vent openings shall be of 0.5 m 2 in the external wall
and the top. If the staircase cannot be ventilated,
because of location or other reasons, a positive pressure
50 Pa shall be maintained inside. The mechanism for
pressurizing the staircase shall operate automatically
with the fire alarm. The roof of the shaft shall be 1 m
above the surrounding roof. Glazing or glass bricks if
used in staircase, shall have fire resistance rating of
minimum 2 h.
C-1.5 Lifts
General requirements of lifts shall be as follows:
a) Walls of lift enclosures shall have a fire rating
of 2 h; lifts shafts shall have a vent at the top
of area not less than 0.2 m 2 .
b) Lift motor room shall be located preferably
on top of the shaft and separated from the shaft
by the floor of the room.
c) Landing doors in lift enclosures shall have a
fire resistance of not less than 1 h.
d) The number of lifts in one row for a lift bank
shall not exceed 4 and the total number of
lifts in the bank (of two rows) shall not exceed
8. A wall of 2 h fire rating shall separate
individual shafts in a bank.
e) Lift car door shall have a fire resistance rating
of half an hour.
f) Collapsible gates shall not be permitted for
lifts and shall have solid doors with fire
resistance of at least 1 h.
g) If the lift shaft and lobby is in the core of the
building, a positive pressure between 25 and
30 Pa shall be maintained in the lobby and a
positive pressure of 50 Pa shall be maintained
in the lift shaft. The mechanism for
pressurization shall act automatically with the
fire alarm; it shall be possible to operate this
mechanically also.
h) Exit from the lift lobby, if located in the
core of the building, shall be through a self-
closing smoke stop door of half an hour fire
resistance.
j) Lifts shall not normally communicate with
the basement; if, however, lifts are in
communication, the lift lobby of the
basements shall be pressurized as in (g), with
self-closing door as in (h).
k) Grounding switch(es), at ground floor level,
shall be provided on all the lifts to enable the
fire service to ground the lifts.
m) Telephone or other communication facilities
PART 4 FIRE AND LIFE SAFETY
65
shall be provided in lift cars for building of
30 m in height and above. Communication
system for lifts shall be connected to fire
control room for the building.
n) Suitable arrangements such as providing slope
in the floor of lift lobby, shall be made to
prevent water used during fire fighting, etc,
at any landing from entering the lift shafts.
p) A sign shall be posted and maintained on
every floor at or near the lift indicating that
in case of fire, occupants shall use the stairs
unless instructed otherwise. The sign shall
also contain a plan for each floor showing the
locations of the stairways.
Alternate source of power supply shall be
provided for all the lifts through a manually
operated changeover switch.
q) Fire Lifts — Following details shall apply for
a fire lift:
1) To enable fire services personnel to reach
the upper floors with the minimum delay,
one fire lift per 1 200 m 2 of floor area
shall be provided and shall be available
for the exclusive use of the firemen in an
emergency.
2) The lift shall have a floor area of not less
than 1 .4 m 2 . It shall have loading capacity
of not less than 545 kg (8 persons lift)
with automatic closing doors of
minimum 0.8 m width.
3) The electric supply shall be on a separate
service from electric supply mains in a
building and the cables run in a route safe
from fire, that is, within the lift shaft.
Lights and fans in the elevators having
wooden paneling or sheet steel
construction shall be operated on 24 V
supply.
4) Fire fighting lift should be provided with
a ceiling hatch for use in case of
emergency, so that when the car gets
stuck up, it shall be easily openable.
5) In case of failure of normal electric
supply, it shall automatically trip over to
alternate supply. For apartment houses,
this changeover of supply could be done
through manually operated changeover
switch. Alternatively, the lift shall be so
wired that in case of power failure, it
comes down at the ground level and
comes to stand-still with door open.
6) The operation of a fire lift is by a simple
toggle or two-button switch situated in a
glass-fronted box adjacent to the lift at
the entrance level. When the switch is on,
landing call-points will become
inoperative and the lift will be on car
control only or on a priority control
device. When the switch is off, the lift
will return to normal working. This lift
can be used by the occupants in normal
times.
7) The words 'Fire Lift' shall be
conspicuously displayed in fluorescent
paint on the lift landing doors at each
floor level.
8) The speed of the fire lift shall be such
that it can reach the top floor from ground
level within 1 min.
C-1.6 Basements
C-l.6.1 Each basement shall be separately ventilated.
Vents with cross-sectional area (aggregate) not less
than 2.5 percent of the floor area spread evenly round
the perimeter of the basement shall be provided in the
form of grills, or breakable stallboard lights or
pavement lights or by way of shafts. Alternatively, a
system of air inlets shall be provided at basement floor
level and smoke outlets at basement ceiling level. Inlets
and extracts may be terrninated at ground level with
stallboard or pavement lights as before, but ducts to
convey fresh air to the basement floor level have to be
laid. Stallboard and pavement lights should be in
positions easily accessible to the fire brigade and
clearly marked 'SMOKE OUTLET' or 'AIR INLET'
with an indication of area served at or near the opening.
C-l.6.2 The staircase of basements shall be of
enclosed type having fire resistance of not less than
2 h and shall be situated at the periphery of the
basement to be entered at ground level only from the
open air and in such positions that smoke from any
fire in the basement shall not obstruct any exit serving
the ground and upper stores of the building and shall
communicate with basement through a lobby provided
with fire resisting self closing doors of 1 h resistance.
For travel distance see 45. If the travel distance exceeds
as given in Table 21, additional staircases shall be
provided at proper places.
C-l.6.3 In multi-storey basements, intake ducts may
serve all basement levels, but each basement levels
and basement compartment shall have separate smoke
outlet duct or ducts. Ducts so provided shall have the
same fire resistance rating as the compartment itself.
Fire rating may be taken as the required smoke
extraction time for smoke extraction ducts.
C-l.6.4 Mechanical extractors for smoke venting
system from lower basement levels shall also be
provided. The system shall be of such design as to
66
NATIONAL BUILDING CODE OF INDIA
operate on actuation of heat/smoke sensitive detectors
or sprinklers, if installed, and shall have a considerably
superior performance compared to the standard units.
It shall also have an arrangement to start it manually.
C-l.6.4.1 Mechanical extractors shall have an internal
locking arrangement, so that extractors shall continue
to operate and supply fans shall stop automatically with
the actuation of fire detectors.
C-l.6.4.2 Mechanical extractors shall be designed to
permit 30 air changes per hour in case of fire or distress
call. However, for normal operation, air changes
schedule shall be as given in 3.4.11.5.
C-l.6.4.3 Mechanical extractors shall have an
alternative source of supply.
C-l.6.4.4 Ventilating ducts shall be integrated with
the structure and made out of brick masonry or
reinforced cement concrete as far as possible and when
this duct crosses the transformer area or electrical
switchboard, fire dampers shall be provided.
C-l.6.5 Use of basements for kitchens working on gas
fuel shall not be permitted, unless air conditioned.
The basement shall not be permitted below the ward block
of a hospital/nursing home unless it is fully sprinkled.
Building services such as electrical sub-stations, boiler
rooms in basements shall comply with the provisions
of the Indian Electricity Act/Rules.
C-l.6.6 If cut outs are provided from basements to
the upper floors or to the atmospheres, all sides cut
out openings in the basements shall be protected by
sprinkler head at close spacing so as to form a water
curtain in the event of a fire.
C-1.7 Openable windows on external walls shall be
fitted with such locks that can be opened by a fireman' s
axe.
C-1.8 All floors shall be compartmented with area not
exceeding 750 m 2 by a separation wall with 2 h fire
rating, for floors with sprinklers the area may be
increased by 50 percent. In long building, the fire
separation walls shall be at distances not exceeding
40 m. For departmental stores, shopping centres and
basements, the area may be reduced to 500 m 2 for
compartmentation. Where this is not possible, the
spacings of the sprinklers shall be suitably reduced.
When reducing the spacing of sprinklers, care should
be taken to prevent spray from one sprinkler impeding
the performance of an adjascent sprinkler head.
C-l.8.1 It is essential to make provisions for drainage
of any such water on all floors to prevent or minimize
water damage of the contents. The drain pipes should
be provided on the external wall for drainage of water
from all floors. On large area floors several such pipes
may be necessary which should be spaced 30 m apart.
Care shall be taken to ensure that the construction of
the drain pipe does not allow spread of fire/smoke from
floor to floor.
C-1.9 Service Ducts/Shafts
a) Service ducts and shafts shall be enclosed by
walls of 2 h and doors of 1 h, fire rating. All
such ducts/shafts shall be properly sealed and
fire stopped at all floor levels.
b) A vent opening at the top of the service shaft
shall be provided having between one-fourth
and one-half of the area of the shaft.
C-1.10 Refuse chutes shall have opening at least 1 m
above roof level or venting purpose and they shall have
an enclosure wall of non-combustible material with
fire resistance of not less than 2 h. They shall not be
located within the staircase enclosure or service shafts,
or air-conditioning shafts inspection panel and doors
shall be tight fitting with 1 h fire resistance; the chutes
should be as far away as possible from exits.
C-l.ll Refuge Area
Provisions contained in 4.12.3 shall apply for all
buildings except multi-family dwellings, refuge area
of not less than 15 m 2 shall be provided on the external
walls.
C-1.12 Electrical services shall conform to the
following;
a) The electric distribution cables/wiring shall
be laid in a separate duct. The duct shall be
sealed at every floor with non-combustible
materials having the same fire resistance as
that of the duct. Low and medium voltage
wiring running in shaft and in false ceiling
shall run in separate conduits;
b) Water mains, telephone lines, intercom lines,
gaspipes or any other service line shall not be
laid in the duct for electrical cables; use of
bus ducts/solid rising mains instead of cables
is preferred;
c) Separate circuits for fire fighting pumps, lifts,
staircases and corridor lighting and blowers
for pressurizing system shall be provided
directly from the main switch gear panel and
these circuits shall be laid in separate conduit
pipes, so that fire in one circuit will not affect
the others. Such circuits shall be protected at
origin by an automatic circuit breaker with
its no-volt coil removed. Master switches
controlling essential service circuits shall be
clearly labelled;
PART 4 FIRE AND LIFE SAFETY
67
d) The inspection panel doors and any other
opening in the shaft shall be provided with
air-tight fire doors having fire resistance of
not less than 2 h;
e) Medium and low voltage wiring running in
shafts, and within false ceiling shall run in
metal conduit. Any 230 V wiring for lighting
or other services, above false ceiling, shall
have 660 V grade insulation. The false ceiling,
including all fixtures used for its suspension,
shall be of non-combustible material and shall
provide adequate fire resistance to the ceiling
in order to prevent spread of fire across ceiling
reference may be made to good practice
[4(29)];
f) An independent and well ventilated service
room shall be provided on the ground level or
first basement with direct access from outside
or from the corridor for the purpose of
termination of electric supply from the
licensees 1 service and alternative supply cables.
The doors provided for the service room shall
have fire resistance of not less than 2 h;
NOTE — If service room is located at the first basement,
it should have automatic fire extinguishing system.
g) If the licensees agree to provide meters on
upper floors, the licensees' cables shall be
segregated from consumers' cables by
providing a partition in the duct. Meter rooms
on upper floors shall not open into stair case
enclosures and shall be ventilated directly to
open air outside; and
h) Suitable circuit breakers shall be provided at
the appropriate points.
C-1.13 Gas supply shall conform to the following:
a) Town Gas/L.P. Gas Supply Pipes — Where
gas pipes are run in buildings, the same shall
be run in separate shafts exclusively for this
purpose and these shall be on external walls,
away from the staircases. There shall no
interconnection of this shaft with the rest of
the floors. LPG distribution pipes shall always
be below the false ceiling. The length of these
pipes shall be as short as possible. In the case
of kitchen cooking range area, apart from
providing hood, covering the entire cooking
range, the exhaust system should be designed
to take care of 30 m 3 per minute per m 2 of
hood protected area. It should have grease
filters using metallic grill to trap oil vapours
escaping into the fume hood.
NOTE — For detailed information on gas pipe
installations, reference may be made to Part 9 'Plumbing
Services, Section 3 Gas Supply'.
b) All wiring in fume hoods shall be of fibre
glass insulation. Thermal detectors shall be
installed into fume hoods of large kitchens
for hotels, hospitals, and similar areas located
in high rise buildings. Arrangements shall be
made for automatic tripping of the exhaust
fan in case of fire. If LPG is used, the same
shall be shut off. The voltage shall be 24 V or
100 V dc operated with external rectifier. The
valve shall be of the hand re-set type and shall
be located in an area segregated from cooking
ranges. Valves shall be easily accessible. The
hood shall have manual facility for steam or
carbon dioxide gas injection, depending on
duty condition; and
c) Gas meters shall be housed in a suitably
constructed metal cupboard located in a well
ventilated space, keeping in view the fact that
LPG is heavier than air and town gas is lighter
than air.
C-1.14 Illumination of Means of Exit
Staircase and corridor lights shall conform to the
following (see 4.16 and 4.17 for additional details):
a) The staircase and corridor lighting shall be
on separate circuits and shall be independently
connected so as it could be operated by one
switch installation on the ground floor easily
accessible to fire fighting staff at any time
irrespective of the position of the individual
control of the light points, if any. It should be
of miniature circuit breaker type of switch so
as to avoid replacement of fuse in case of
crisis;
b) Staircase and corridor lighting shall also be
connected to alternative supply. The
alternative source of supply may be provided
by battery continuously trickle charged from
the electric mains;
c) Suitable arrangements shall be made by
installing double^throw switches to ensure that
the lighting installed in the staircase and the
corridor does not get connected to two sources
of supply simultaneously. Double throw
switch shall be installed in the service room
for terminating the stand-by supply;
d) Emergency lights shall be provided in the
staircase and corridor; and
e) All wires and other accessories used for
emergency light shall have fire retardant
property.
C-1.15 A stand-by electric generator shall be installed
to supply power to staircase and corridor lighting
circuits, fire lifts, the stand-by fire pump, pressurization
68
NATIONAL BUILDING CODE OF INDIA
fans and blowers, smoke extraction and damper
systems in case of failure of normal electric supply.
The generator shall be capable of taking starting current
of all the machines and circuits stated above
simultaneously. If the stand-by pump is driven by diesel
engine, the generator supply need not be connected to
the stand-by pump. Where parallel HV/LV supply from
a separate sub-station is provided with appropriate
transformer for emergency, the provision of generator
may be waived in consultation with the Authority.
C-1.16 Transformers shall conform to the following:
a) A sub-station or a switch-station with oil filled
equipment shall not be located in the building.
The sub-station structure shall have separate
fire resisting walls/surroundings and shall
necessarily be located at the periphery of the
floor having separate access from fire escape
stair case. The outside walls, ceiling, floor,
openings including doors and windows to the
sub-station area shall be provided with a fire
resisting door of 2 h fire rating. Direct access
to the transformer room shall be provided,
preferably from outside fire escape staircase.
b) The sub-station area needs to be maintained at
negative air pressures and area in sub-station
shall not be used as storage/dump areas.
c) When housed inside the building, the
transformer shall be of dry type and shall be
cut off from the other portion of premises by
walls/doors/cutout having fire resistance
rating of 4 h.
C-1.17 Air-conditioning shall conform to the
following:
a) Escape routes like staircases, common
corridors, lift lobbies, etc, shall not be used
as return air passage.
b) The ducting shall be constructed of substantial
gauge metal in accordance with good practice
[4(31].
c) Wherever the ducts pass through fire walls or
floors, the opening around the ducts shall be
sealed with materials having fire resistance
rating of the compartment.
d) Where duct crosses a compartment which is
fire rated, the ducts shall be fire rated for same
fire rating. Further depending on services
passing around the duct work, which may get
affected in case of fire temperature rising, the
ducts shall be insulated.
e) As far as possible, metallic ducts shall be used
even for the return air instead of space above
the false ceiling.
f) Where plenum is used for return air passage,
ceiling and its fixtures shall be of non-
combustible material.
g) The materials used for insulating the duct
system (inside or outside) shall be of non-
combustible materials. Glass wool shall not
be wrapped or secured by any material of
combustible nature.
h) Area more than 750 m 2 on individual floor
shall be segregated by a fire wall and
automatic fire dampers for isolation shall be
provided [see (j)].
j) Air ducts serving main floor areas, corridors,
etc, shall not pass through the staircase
enclosure.
k) The air-handling units shall be separate for
each floor and air ducts for every floor shall
be separated and in no way inter-connected
with the ducting of any other floor.
m) If the air-handling unit serves more than one
floor, the recommendations given above shall
be complied with in addition to the conditions
given below:
1) proper arrangements by way of automatic
fire dampers working on smoke detector/
or fusible link for isolating all ducting at
every floor from the main riser shall be
made.
2) When the automatic fire alarm operates,
the respective air-handling units of the air-
conditioning system shall automatically
be switched off.
n) The vertical shaft for treated fresh air shall
be of masonry construction.
p) The air filters of the air-handling units shall
be of non-combustible materials.
q) The air-handling unit room shall not be used
for storage of any combustible materials.
r) Inspection panels shall be provided in the
main trunking to facilitate the cleaning of
ducts of accumulated dust and to obtain access
for maintenance of fire dampers.
s) No combustible material shall be fixed nearer
than 150 mm to any duct unless such duct is
properly enclosed and protected with non-
combustible material (glass wool or spunglass
with neoprene facing enclosed and wrapped
with aluminimum sheeting) at least 3.2 mm thick
and which would not readily conduct heat.
t) Fire Dampers
1) These shall be located in conditioned air
ducts and return air ducts/passages at the
following points:
i) At the fire separation wall.
PART 4 FIRE AND LIFE SAFETY
69
ii) Where ducts/passages enter the
central vertical shaft,
iii) Where the ducts pass through floors,
iv) At the inlet of supply air duct and the
return air duct of each compartment
on every floor.
2) The dampers shall operate automatically
and shall simultaneously switch off the
air-handling fans. Manual operation
facilities shall also be provided.
NOTE — For blowers, where extraction system
and duct accumulators are used, dampers shall be
provided.
3) Fire/smoke dampers (for smoke extraction
shafts) for buildings more than 24 m in
height.
For apartment In non-ventilated
houses lobbies/ corridors
operated by fusible
link/smoke detectors
and with manual
control.
For other On operation of smoke
buildings detection system and
with manual control.
4) Automatic fire dampers shall be so
arranged as to close by gravity in the
direction of air movement and to remain
tightly closed on operation of a fusible
link/smoke detector.
C-1.18 Provisions of boiler and boiler rooms shall
conform to Indian Boiler Act. Further, the following
additional aspects may be taken into account in the
location of boiler room:
a) The boilers shall not be allowed in sub-
basement, but may be allowed in the
basements away from the escape routes.
b) The boilers shall be installed in a fire resisting
room of 4 h fire resistance rating, and this
room shall be situated on the periphery of the
basement. Catch-pits shall be provided at the
low level.
c) Entry to this room shall be provided with a
composite door of 2 h fire resistance.
d) The boiler room shall be provided with fresh
air inlets and smoke exhausts directly to the
atmosphere.
e) The furnace oil tank for the boiler, if located
in the adjoining room shall be separated by
fire resisting wall of 4 h rating. The entrance
to this room shall be provided with double
composite doors. A curb of suitable height
shall be provided at the entrance in order to
prevent the flow of oil into the boiler room in
case of tank rupture,
f) Foam inlets shall be provided on the external
walls of the building near the ground level to
enable the fire services to use foam in case of
fire.
C-2 PROVISION OF FIRST-AID FIRE FIGHTING
APPLIANCES
The first-aid fire fighting equipment shall be provided
on all floors, including basements, lift rooms, etc, in
accordance with good practice [4(21)] in consultation
with the Authority.
C-3 FIRE ALARM SYSTEM
C-3.1 All buildings with heights of 15 m or above
shall be equipped with manually operated electrical
fire alarm (MOEFA) system and automatic fire alarm
system in accordance with good practice [4(18)] and
[4(19)]. However, apartment buildings between 15 m
and 30 m in height may be exempted from the
installation of automatic fire alarm system provided
the local fire brigade is suitably equipped for dealing
with fire in a building of 15 m in height or above and
in the opinion of the Authority, such building does not
constitute a hazard to the safety of the adjacent property
or occupants of the building itself.
C-3.1. 1 Manually operated electrical fire alarm system
shall be installed in a building with one or more call
boxes located at each floor. The call boxes shall
conform to good practice [4(18)] and [4(19)].
C-3.1.2 The installation of call boxes in hostels and
such other places where these are likely to be misused
shall as far as possible be avoided. Location of call boxes
in dwelling units shall preferably be inside the building.
C-4 LIGHTNING PROTECTION OF BUILDINGS
The lightning protection for buildings shall be provided
as given in Part 8 'Building Services, Section 2
Electrical Installations'.
C-5 FIRE CONTROL ROOM
For all buildings 15 m in height or above and apartment
buildings with a height of 30 m and above, there shall
be a control room on the entrance floor of the building
with communication system (suitable public address
system) to all floors and facilities for receiving the
message from different floors. Details of all floor plans
along with the details of fire fighting equipment and
installations shall be maintained in the fire control
room. The fire control room shall also have facilities
to detect the fire on any floor through indicator boards
connection; fire detection and alarm systems on all
floors. The fire staff incharge of the fire control room
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NATIONAL BUILDING CODE OF INDIA
shall be responsible for the maintenance of the various
services and fire fighting equipment and installations
in co-ordination with security, electrical and civil staff
of the building.
C-6 FIRE OFFICER FOR HOTELS, BUSINESS
AND MERCANTILE BUILDINGS WITH HEIGHT
MORE THAN 30 m
C-6.1 A qualified Fire Officer with experience of not
less than 3 years shall be appointed who will be
available on the premises.
C-6.2 The Fire Officer shall:
a) maintain the fire fighting equipment in good
working condition at all times,
b) prepare fire orders and fire operational plans
and get them promulgated,
c) impart regular training to the occupants of the
buildings in the use of fire fighting
equipments provided on the premises and
keep them informed about the fire emergency
evacuation plan,
d) keep proper liaison with city Fire Brigade, and
e) ensure that all fire precautionary measures are
observed at the times.
NOTE — Competent authority having jurisdiction may
insist on compliance of the above rules in case of
buildings having very large areas even if the height is
less than 30 m.
C-7 HOUSE KEEPING
To eliminate fire hazards, good house keeping, both
inside and outside the building, shall be strictly
maintained by the occupants and/or the owner of the
building.
C-8 FIRE DRILLS AND FIRE ORDERS
Fire notices/orders shall be prepared to fulfil the
requirements of fire fighting and evacuation from the
buildings in the event of fire and other emergency. The
occupants shall be made thoroughly conversant with
their actions in the event of emergency, by displaying
fire notices at vantage points and also through regular
training. Such notices should be displayed prominently
in broad lettering.
For guidelines for fire drills and evacuation procedures
for high rise buildings, see Annex E.
C-9 COMPARTMENTATION
The building shall be suitably compartmentalized so
that fire/smoke remain confined to the area where fire
incident has occurred and does not spread to the
remaining part of the building.
C-10 HELIPAD
For high rise buildings above 60 m in height, provision
for helipad should be made.
C-ll MATERIALS FOR INTERIOR
DECORATION/FURNISHING
The use of materials which are combustible in nature
and may spread toxic fume/gases should not be used
for interior decoration/furnishing, etc.
ANNEX D
(Clauses 6.7.3.3 (a) and 6.7.5)
FIRE PROTECTION CONSIDERATIONS FOR VENTING IN INDUSTRIAL BUILDINGS
D-l APPLICATION AND SCOPE
D-l.l The provisions given below are applicable
only to single storey industrial buildings (factories
and storage buildings) covering large floor areas
without sub-dividing/separating walls which are
usually designed to meet modern production
methods.
D-l. 2 The requirements of fire and explosion venting
of industrial buildings, as dealt with in this section,
fall under two categories:
a) Smoke and fire venting, and
b) Explosion relief vents.
D-2 SMOKE AND FIRE VENTING
,/■■
D-2.1 The basic considerations for formulating the
design and other requirements for smoke and fire vents
are as given in D-2.1.1 to D-2. 1.20.
D-2.1.1 The smoke and hot combustion products from
a fire, being lighter than the surrounding air, tend to
rise and on reaching the roof or ceiling spread out
(mushroom) on all sides and form a layer which floats
on top of the cold air beneath. In the absence of vents,
this layer becomes progressively deeper until the whole
building is filled with hot smoky gases. The time
consumed for this to happen may be only a few
PART 4 FIRE AND LIFE SAFETY
71
minutes, depending on variables like, type of materials
on fire, process/storage conditions involved, etc.
D-2.1.2 The hot gases at the roof level moved by
convection currents contribute to rapid lateral spread
of fire.
D-2.1.3 The provision of properly designed and
suitably located vents in adequate number helps the
speedy removal of smoke and hot gases, thereby
preventing spread of fire, besides reducing risks of
explosion of unburnt gases and reducing damage to
the contents and structure of the building by heat and
smoke. In addition, they facilitate fire fighting
operations, and minimize personal hazards to the
firemen.
D-2.1.4 The time taken for accumulation of smoke
and hot gases within a building on fire being very short,
the venting devices installed shall be designed to
operate in the early stage of the fire and must be
automatic so as to ensure speed and efficiency in their
operation.
D-2.1.5 The smoke and fire venting system shall be
designed in such a manner as to keep the temperature
of the combustion products from the fire as low as
possible, preferably below approximately 150°C.
D-2.1.6 Automatic venting systems are complementary
to the fire extinguishing systems, and automatic
sprinklers, where provided, should operate before the
operation of the vents; otherwise, venting may delay
sprinkler operation.
D-2.1.7 It is easier to vent a building of smoke than
clear it of smoke once it has been filled.
D-2.1.8 Venting is particularly desirable in large area
industrial buildings or warehouses, windowless
buildings, underground structures or in areas housing
hazardous operations. Automatic fire vents shall be
provided for all industrial occupancies (including
storage buildings) classified as medium hazard or
above having floor areas exceeding 750 m 2 , irrespective
of whether they are compartmentalized or not.
D-2.1.9 These provisions do not cover other aspects,
of ventilation (or lighting) designed for regulation of
temperature within a building for personal comfort or
meeting process needs.
D-2.1.10 Similarly, fire and smoke venting requirements
as given here under are also not applicable to multi-storey
buildings, as their requirements are different and more
complex.
D-2.1,11 It is difficult to determine precise venting
requirements on account of the many variables
involved. For instance, the rate of combustion varies
appreciably according to the nature, shape, size and
packaging of the combustible materials as well as the
size, height and disposition of the stacks of materials.
D-2.1.12 In industrial buildings of floor area less than
750 m 2 and used as low fire hazard occupancies,
conventional ventilators fitted high up near the eaves
of the external walls may serve as vents for smoke and
hot gases, provided care is taken to ensure that they
are kept open at all times or are designed to open
automatically in case of fire.
D-2.1.13 Extinction of fires by closing the doors and
windows is not likely in the case of industrial buildings
because of their large size, where sufficient air to
sustain the fire at least in the initial stages can be
expected to be present.
D-2.1.14 Of the two types of building ventilation,
namely, vertical and horizontal, vertical ventilation is
the one commonly adopted in the case of single storey
industrial buildings.
D-2.1.15 Since 70 to 80 percent of heat produced in a
fire is convective heat, the ventilation system has to
be suitably designed to ensure early outflow of the heat
and thereby minimize fire spread.
D-2.1.16 Combustible roof linings shall be avoided,
as they themselves will contribute to the spread of fire,
thereby multiplying the venting problems.
D-2.1.17 A wind blowing across a flat roof or a roof
with a pitch under 40° produces a negative pressure,
that is, it tends to draw gases out of the building and so
aids venting of hot gases. Wind blowing across a roof
of pitch greater than 40° will draw gases out on the
leeward side, but oppose outward flow on the
windward side of the roof.
D-2.1.18 For vents to work at full efficiency, the area
of the inlets for cold air entering the compartment must
equal at least the total area of the vents. Ideally, the
inlets shall be as close to the ground as possible.
D-2.1.19 Where roof verits are installed in a single-
storey building any neighbouring buildings,
particularly those of more than one storey, will be
subject to some degree of exposure hazard either from
flying birds or radiation, or both, as a result.
D-2.1.20 If vents are to be installed, the size, design,
number and disposition of the vents and the associated
roof screens/curtain boards have to be assessed after
careful analysis of the various factors stated
under D-2.1.11 above, as well as other related factors
like type of building construction, nature and height
of roof, process hazards, exposure hazard, etc.
D-2.2 Venting Area
D-2.2.1 The estimated requirements for ventilation are
72
NATIONAL BUILDING CODE OF INDIA
largely based on the assumed build-up of the fire from
the time of initial outbreak to the time of effective fire
fighting action by fire brigade.
D-2.2.2 The vent area required to be provided shall
be approximately proportional to the perimeter of the
fire area, because the entrained air forms the bulk of
the vented gases.
D-2.2.3 The effective area shall be the minimum cross-
sectional area through which the hot gases must flow
out to the atmosphere.
D-2.2.4 No consideration shall be given to the
increased air movement obtained by power operated
fans, since it must be assumed that in the event of fire,
power will be interrupted, or fans damaged by heat.
D-2.2.5 The total vent areas to be provided shall be
as per the following ratios of effective area of vent
openings to floor area for various occupancy
classifications indicated:
a) Low heat release content 1: 150
(Sub-division G-l)
b) Moderate heat release content 1 : 1 00
(Sub-division G-2)
c) High heat release content 1:30 to 1 :50
(Sub-division G-3)
D-2.3 Types of Vents
D-2.3.1 Venting shall be accomplished by any of the
types such as monitors continuous gravity vents, until
type vents or sawtooth roof skylights.
D-2,3.2 Where monitor type vents are installed, wired
glass or metal panels shall be used only if the sash is
arranged to open automatically.
D-2.3.3 The use of plain thin glass for venting shall
be avoided on account of its unpredictable behaviour
during fire. However, if glass or other suitable plastic
sheet materials with early disintegration characteristics
are used, they should be designed for automatic
operation.
D-2.3.4 Where monitors or unit type vents are used,
the panels shall be hinged at the bottom and designed
to open automatically. Both sides of the vents shall be
designed to vent simultaneously to ensure that their
effectiveness at the time of fire is not in any way
impeded by wind direction.
D-2.3. 5 Where movable shutters are provided
for continuous gravity vents, these shall open
automatically in the event of fire.
D-2.3.6 Unit type vents shall be of relatively small
area, ranging between 1 m 2 and 9 m 2 , having light
weight metal frames and housing with hinged dampers
which shall be designed for both manual and automatic
operation.
D-2.3.7 Sawtooth roof skylight shall be considered as
satisfactory for venting purposes only when designed
for automatic operation.
D-2.3.8 Likewise, exterior wall windows shall not be
reckoned as satisfactory means for venting of fire gases
and smoke in industrial buildings. However, they may
be reckoned as additional means of venting when, they
are located close to the eaves and are provided with
ordinary glass or movable sash arranged for both
manual and automatic operation.
D-2.3.9 Baffles shall not be installed inside vents, as
they greatly reduce the effective area for venting.
D-2.4 Vent Operation
D-2.4.1 The vents shall be automatic in operation,
unless where specified in these provisions that they
shall be designed for both manual and automatic
operation.
D-2.4.2 The release mechanism shall be simple for
operation and independent of electrical power, since
electrical services may be interrupted by fire.
D-2.4.3 The automatic operation of vents shall be
achieved by actuation of fusible links or other types of
heat and smoke detectors, or by interlocking with
operation of sprinkler system or any other automatic
fire extinguishing system covering the area. Following
their release, the vents shall be designed to open by a
system of counterweights and associated equipment
utilizing the force of gravity or spring loaded levers.
D-2.4.4 Automatic fire alarm system, where installed,
shall be coupled to the automatic vents to ensure
simultaneous operation.
D-2.4.5 Automatic sprinklers, where installed, shall
operate before the vents open in order to avoid any
likely delay in sprinkler operation. However, heat
actuated devices used for vent release shall be suitably
shielded from sprinkler discharge so that water does
not delay their action.
D-2.4.6 Premises where height of roof apex is 10 m
or more or where the materials handled or stored have
high smoke producing characteristics, in addition to
fusible links, the vent release mechanism shall be
interlinked to smoke actuated automatic fire detectors
to ensure early operation of vents.
D-2.4.7 Non-corrosive materials shall be used for
hinges, hatches and other related parts to ensure long
fail-safe operation of the vents.
D-2.4.8 In case of any doubts regarding the types of
vents required to be installed for any particular
PART 4 FIRE AND LIFE SAFETY
73
occupancy, authorities having jurisdiction shall be
consulted.
D-2.5 Size, Spacing and Disposition of Vents
D-2.5.1 Vents shall be correctly sited to ensure their
functional efficiency. Ideally, they shall be sited at the
highest point in each area to be covered.
D-2.5. 2 They shall, as far as possible, be located
immediately above the risk to be protected so as to
allow free and speedy removal of smoke and other
combustion products in the event of fire.
D-2.5.3 The minimum dimension for an effective vent
opening shall be not less than 1.25 m in any direction.
D-2.5.4 The spacing of the individual vents shall be
based on the principle that more number of well
distributed smaller vents are more effective than less
number of badly located larger vents.
D-2.5.5 The maximum spacing between vents for the
three occupancy classifications shall be as follows:
a) Low heat release content — 45 m between
centres
b) Moderate heat release content — 36 to 37 m
between centres
c) High heat release content — 22.5 to 30 m
between centres, depending on the severity
of fire potential.
D-2.5.6 Vents shall be placed in a sheltered situation
where advantage can be taken of the prevailing wind.
The design of the vent shall be such as to produce a
suction effect. A wind blowing across a flat roof or
one with a pitch be 40° produces a negative pressure,
that is, it tends to draw gases out of the building and so
aids venting of hot gases. Wind blowing across a roof
of pitch greater than 40° will draw gases out on the
leeward side, but oppose outward flow on the
windward side of the roof.
D-2.5.7 Low level inlets, with total area not less than
the total area of vents, shall be provided to permit
outside air to be drawn in to aid automatic venting.
These inlets, which may be in the form of doors,
windows or such other openings, shall be designed for
manual operation when desired.
D-2.6 Roof Screens or Curtain Boards
D-2.6.1 Industrial buildings with large areas and
having no sub-division/separating walls limiting the
area of individual compartments to 750 m 2 or less, shall
be provided with roof screens or curtain boards.
These screens which extend from the roof downwards
at specific intervals not only prevent lateral spread of
heat and smoke in the event of fire below, but
substantially assist in early operation of automatic
sprinklers and vents.
D-2.6.2 They shall be of sheet metal or any other
substantial non-combustible material strong enough to
withstand damage by heat or impact.
D-2.6.3 They shall be reasonably gas-tight, although
small openings for passage of pipes, conduits, etc, shall
be permitted.
D-2.6.4 They shall extend down from the roof/ceiling
for a minimum depth of 2.2 m. Around specific
hazards, the depth shall be 4 m. Where roof/ceiling
height exceeds 15 m they shall extend down to within
3 m of the floor. For pitched sawtoothed roofs, they
shall extend down to truss level dividing the roof into
compartments.
D-2.6.5 In moderate hazard occupancies, the distance
between the screens/curtain boards shall not exceed
75 m and the curtained areas shall be limited to a
maximum of 4 500 m 2 .
D-2.6.6 In high hazard occupancies, the distance
between screens shall not exceed 30 m and the
curtained area shall be limited to 750 m 2 .
D-2.6.7 The curtained roof area shall be so arranged
that they effectively aid in the venting of smoke and
hot gases through the automatic vents provided in each
area.
D-2.6.8 In sprinklered buildings, the screens shall
preferably be so located as to coincide with the
individual sprinkler system areas.
D-3 EXPLOSION RELIEF VENTS
D-3.1 Industrial premises where combustible dusts can
accumulate or where flammable gases, vapours or mists
in explosive concentrations may be present are
constantly exposed to explosion hazards. Pressures
developed by such explosions may be of the order of
7 x 10 5 Pa and ordinary buildings will not be able to
withstand the shock of such pressures. Hence, such
buildings require explosion relief vents for preventing
structural damage.
D-3.2 Basic Principle/Considerations
D-3. 2.1 Most ordinary building walls will not
withstand a sustained internal pressure as great as
6.9 x 10 3 Pa. Hence, explosion relief vents for
buildings must be designed to operate at pressures well
below those at which the building walls will fail.
D-3.2.2 There is a rise in pressure during an explosion
within an enclosure even with open, unobstructed
vents, and any delay in opening the venting devices
increases that pressure.
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NATIONAL BUILDING CODE OF INDIA
D-3.2.3 Structural damage can be minimized by
locating hazardous operations or equipment outside
buildings and cut off from other operations by a
pressure resisting wall. Such isolated processes or
equipment shall be housed in single-storey buildings
properly vented and a device provided at the inlet of
the collector which will prevent an explosion from
blowing back through the duct work and into the
building.
D-3.2.4 Where highly hazardous operations cannot be
located outside of main buildings they shall be
segregated by pressure resisting walls and each such
unit shall be ventilated outdoors. External walls may
be of heavy construction if equipped with suitable vents
or high weight panels which blow out easily.
D-3.2.5 Operations or equipment involving explosion
hazards shall not be permitted in basements or areas
partially below grade.
D-3.2.6 Fire can be expected to follow an explosion in
most occupancies, so that any fixed fire extinguishing
equipment, like sprinklers, if installed, shall be such
that only the minimum damage is caused to it.
D-3.2.7 For a given material, the finer the particle size
of the dust, the more violent is the explosion. Some
materials, such as aluminium powder, hydrogen, and
acetylene, are difficult to vent effectively due to the
rapid rate of pressure rise. Some slow burning
materials, such as coal dust in a confined space, may
do much damage because of the longer duration of
their presence. Some dusts, such as magnesiusm,
titanium and zirconium and several metal hydrides may
react with water and ignite in some common inert
gases, such as nitrogen and carbon dioxide.
D-3.2.8 The maximum explosion pressure in a vented
structure decreases as the size of the vent increases, but
is independent of the rupturing pressure of a diaphragm.
D-3.2.9 The most effective vent for the release of
explosion pressures is an unobstructed vent opening.
D-3.2.10 Pressure required to rupture diaphragms of
the same area and material directly varies with the
thickness of the material.
D-3.2.11 The slower the rate of pressure rise, the more
easily can the explosion be vented.
D-3.2.12 The degree of venting required is directly
proportional to the degree of explosion hazard.
D-3.2.13 Experience has shown that most explosions
of dusts, vapours and gases do not involve a large part
of the total volume of the enclosure, and frequently
occur near the upper or lower limits of the explosive
range. Consequently, such explosions are relatively
weak compared with the optimum.
D-3.2.14 Rectangular unrestricted vents are as
effective as square vents of equal area.
D-3.3 Types of Explosion Relief Vents
D-3.3.1 The explosion relief vents shall be any one or
more of the following types, depending on individual
requirements as assessed by the Authority. Open or
unobstructed vents, louvers, open roof vents, hanger
type doors, building doors, windows, roof or wall
panels or movable fixed sash.
D-3.3.2 The effect of external wind pressure or suction
on these devices shall be taken into consideration while
designing and selecting the type of vents, since wind
pressures may reach over 2 x 10 5 Pa in severe wind
storms.
D-3.3.3 The type of vent for explosion relief for any
occupancy shall be selected with life safety as the
primary aim followed by minimum damage to
property.
D-3.3.4 Where large hanger type doors or metal
curtain doors in side walls are used as vents care shall
be taken to ensure that they are kept wide open during
operations.
D-3.3.5 Where weather hoods are used to cover roof
vents, they shall be as light as possible and lightly
attached so as to enable them to be blown off quickly
when an explosion occurs.
D-3.3.6 Doors and windows when used as explosion
vents shall be installed to swing outwards. Doors shall
have friction, spring or magnetic latches that will
function automatically to permit the door to open under
slight internal pressure.
D-3.3.7 Movable sash shall be of the top or bottom
hinged or protected type. These shall be equipped with
a latch or friction device to prevent accidental opening
due to wind action or intrusion. Such latches or locks
shall be well maintained.
D-3.3.8 Fixed sash shall be set in place with very light
wall anchorages, or, if right, shall be securely fitted
and glazed with plastic panes in plastic putty.
D-3.3.9 Where the process is such that the whole of a
building or a room may be desirable to arrange for a
lightly constructed wall or roof to collapse and thus
avert the worst effects of an explosion.
D-3.4 Design, Size and Disposition of Vents
D-3.4.1 The required area of explosion vents shall
ordinarily depend on the expected maximum intensity
of an explosion in the occupancy, the strength of the
structure, the type of vent closure and other factors.
D-3.4.2 Venting shall be planned in such a manner as
PART 4 FIRE AND LIFE SAFETY
75
to prevent injury to personnel and damage to
explosures. In congested locations, substantial ducts
or diverters shall be provided to direct the blast.
D-3.4.3 When ductwork is used, the ducts shall be of
sufficient strength to withstand the maximum expected
explosion pressure.
D-3.4.4 Where explosions are likely within duct and
piping systems, they shall be vented by the use of
suitable diaphragms designed to blow out at a
predetermined pressure. There shall be no physical
connection between ductwork system for more than
one collector.
D-3.4.5 In large structures, the position of vents shall
be relative to the point of origin of explosion, when it
can be determined.
D-3.4.6 Where relatively slow explosions involving
coal dust, chlorinated solvents, etc, are involved, light,
hinged swinging panels may be preferred to diaphragm
type of vents.
D-3.4.7 Obstructions of any kind blocking the vents
from the risk covered shall be avoided, particularly
where risks of rapid violent explosions are present.
D-3.4.8 Counter weights add to the inertia of the vents
and so shall be avoided.
D-3.4.9 Various relieving devices, including devices
actuated by detonators, shall start to open at as low a
pressure as possible. They shall be of light construction,
so that full opening can be quickly attained.
D-3.4.10 Vents shall be of such size and design as to
prevent rupture of the protected device or apparatus.
D-3.4.11 Skylights or monitors with movable sash that
will open outwards, or fixed sash containing panes of
glass or plastic that will blow out readily under pressure
from within, can be used to supplement wall vents or
windows, provided resistance to their displacement or
opening is kept as low as consistent with the
requirements for structural strength,
D-3.4.12 Flexible plastic sheets when used for vent
closures shall be installed in slotted frames in such a
way that pressure from within bulges the sheets and
releases them from the holding frame.
D-3.4.13 Fragile sheets made of plastic, when used
for vent closures, shall be thin sheets that will crack or
rupture under less pressure than single strength glass.
For this reason use of transparent or translucent plastic
sheets is more advantageous instead of glass in window
sash.
D-3.4.14 If closed vents are used they shall be larger
in area than unenclosed vents to provide equivalent
explosion pressure relief.
D-3.4.15 Small enclosures, such as machines, shall
be vented more generously than buildings, because if
an explosion occurs in a machine, its entire volume
may be involved.
D-3.4.16 Vents for the protection of buildings and
equipment shall be installed on the following basis:
D-3.4.16.1 Small enclosures of less than 30 m 3 ,
machines and ovens of light construction: 1 000 cm 2
for each 0.3 m 3 to 0.9 m 3 .
D-3.4.16.2 For small enclosures of more substantial
construction having reasonably high bursting strength:
1 000 cm 2 for each 0.9 m 3 .
D-3.4.16.3 Fairly large enclosures of 30 to 700 m 3 ,
such as bins, silos, rooms, storage tanks, etc: 1 000 cm 2
for each 0.9 m 3 to 1.5 m 3 . In these cases, attempt shall
be made to the extent possible to predict the likely point
of origin of the explosion in relation to the vent.
D-3.4.16.4 Large rooms and buildings over 700 m 3
containing hazardous equipment comprising a small
fraction of the entire volume:
a) For heavy reinforced concrete, walls —
100 cm 2 for each 2.25 m 3 .
b) For light reinforced concrete, brick or wood
construction — 1 000 cm 2 for each 1.65 m 3
to 2.25 m 3 .
c) For lightweight construction such as
prefabricated panels — 1 000 cm 2 for each
1.5 m 3 to 1.65 m 3 .
D-3.4.16.5 Large rooms or building over 700 m 3
containing hazardous equipment comprising a large
part of the entire volume of a room or building shall
be vented as generously as possible 1 000 cm 2 for each
0.3 m 3 to 1.05 m 3 .
D-3.4.16.6 In order to obtain these ratios, the size of
the building or room must be limited. For some
hazardous materials, such as hydrogen, acetylene,
carbon disulphide, etc, these limits are extremely low.
D-3.4.17 Emphasis shall always be placed on
segregating hazardous areas by means of firewalls or
separating walls to prevent spread of fire.
D-3.4.18 Interior walls of light construction, such as
tile, shall be avoided in hazardous locations, since they
can cause injuries to personnel in the event of an
explosion.
76
NATIONAL BUILDING CODE OF INDIA
ANNEX E
(Clause C-8)
GUIDELINES FOR FIRE DRILL AND EVACUATION PROCEDURES FOR
HIGH RISE BUILDINGS (ABOVE 15 m IN HEIGHT)
E-l INTRODUCTION
In case of fire in a high rise building, safe evacuation
of its occupants may present serious problems unless
a plan for orderly and systematic evacuation is prepared
in advance and all occupants are well drilled in the
operation of such plan. These guidelines are intended
to assist them in this task.
E-2 ALARMS
Any person discovering fire, heat or smoke shall
immediately report such condition to the fire brigade,
unless he has personal knowledge that such a report
has been made. No person shall make, issue, post or
maintain any regulation or order, written or verbal, that
would require any person to take any unnecessary
delaying action prior to reporting such condition to
the fire brigade.
E-3 DRILLS
E-3.1 Fire drills shall be conducted, in accordance with
the Fire Safety Plan, at least once every three months
for existing buildings during the first two years.
Thereafter, fire drills shall t^e conducted at least once
every six months.
E-3.2 All occupants of the building shall participate
in the fire drill. However, occupants of the building,
other than building service employees, are not required
to leave the floor or use the exits during the drill.
E-3.3 A written record of such drills shall be kept on
the premises for a three years period and shall be readily
available for fire brigade inspection.
E-4 SIGNS AND PLANS
E-4.1 Signs at Lift Landings
A sign shall be posted and maintained in a conspicuous
place on every floor at or near the lift landing in
accordance with the requirements, indicating that in
case of fire, occupants shall use the stairs unless
instructed otherwise. The sign shall contain a diagram
showing the location of the stairways except that such
diagram may be omitted, provided signs containing
such diagram are posted in conspicuous places on the
respective floor.
A sign shall read "IN CASE OF FIRE, USE STAIRS
UNLESS INSTRUCTED OTHERWISE". The lettering
shall be at least 12.5 mm block letters in red and white
background. Such lettering shall be properly spaced
to provide good legibility. The sign shall be at least
250 mm x 300 mm, where the diagram is also
incorporated in it and 62.5 mm x 250 mm where the
diagram is omitted. In the latter case, the diagram sign
shall be at least 200 mm x 300 mm. The sign shall be
located directly above a call-button and squarely
attached to the wall or partition. The top of the sign
shall not be above 2 m from the floor level.
E-4.2 Floor Numbering Signs
A sign shall be posted and maintained within each
stair enclosure on every floor, indicating the number
of the floor, in accordance with the requirements
given below.
The numerals shall be of bold type and at least 75 mm
high. The numerals and background shall be in
contrasting colours. The sign shall be securely attached
to the stair side of the door.
E-4.3 Stair and Elevator Identification Signs
Each stairway and each elevator back shall be identified
by an alphabetical letter. A sign indicating the letter of
identification shall be posted and maintained at each
elevator landing and on the side of the stairway door
from which egress is to be made, in accordance with
the requirements given below:
The lettering on the sign shall be at least 75 mm high,
of bold type and of contrasting colour from the
background. Such signs shall be securely attached.
E-4.4 Stair Re-entry Signs
A sign shall be posted and maintained on each floor
within each stairway and on the occupancy side of the
stairway where required, indicating whether re-entry
is provided into the buildjfcg and the floor where
such re-entry is provided, in accordance with the
requirements given below:
The lettering and numerals of the signs shall be at least
12.5 mm high of bold type. The lettering and
background shall be of contrasting colours and the
signs shall be securely attached approximately 1.5 m
above the floor level.
E-4.5 Fire command station shall be provided with
floor plan of the building and other pertinent
information relative to the service equipment of the
building.
PART 4 FIRE AND LIFE SAFETY
77
E-5 FIRE SAFETY PLAN
E-5.1 A format for the Fire Safety Plan shall be as
given in E-8.
E-5.2 The applicable parts of the approved Fire Safety
Plan shall be distributed to all tenants of the building
by the building management when the Fire Safety Plan
has been approved by the Fire Authority.
E-5.3 The applicable parts of the approved Fire Safety
Plan shall then be distributed by the tenants to all their
employees and by the building management to all their
building employees.
E-5.4 Where the owner of the building is also an
occupant of the building, he shall be responsible for
the observance of these rules and the Fire Safety Plan
in the same manner as a tenant.
E-5.5 In the event there are changes from conditions
existing at the time the Fire Safety Plan for the building
was approved, and the changes are such so as to require
amending the Fire Safety Plan, within 30 days after
such changes, an amended Fire Safety Plan shall be
submitted to the fire brigade for approval
E-6 FIRE COMMAND STATION
A Fire Command Station shall be established in the
lobby of the building on the entrance floor. Such
command station shall be adequately illuminated.
E-7 COMMUNICATIONS AND FIRE ALARM
A means of communication and fire alarm for use during
fire emergencies shall be provided and maintained by
the owner or person in charge of the building.
E-8 FIRE SAFETY PLAN FORMAT
E-8.1 Building Address
Street and Pin Code Number
Telephone Number
E-8.2 Purpose and Objective
E-8.2.1 Purpose
To establish method of systematic, safe and orderly
evacuation of an area or building by its occupants in
case of fire or other emergency, in the least possible
time, to a safe area by the nearest safe means of egress;
also the use of such available fire appliances (including
sounding of alarms) as may have been provided for
controlling or extinguishing fire and safeguarding of
human life.
E-8.2.2 Objective
To provide proper education as a part of continuing
employee indoctrination and through a continuing
written programme for all occupants, to ensure prompt
reporting of fire, the response of fire alarms as
designated, and the immediate initiation of fire safety
procedures to safeguard life and contain fire until the
arrival of the fire brigade.
E-8.3 Fire Safety Director
a) Name
b) Regularly assigned employment — Title
c) Regularly assigned location
d) How is he notified when at regular location?
e) How is he notified when not at regular location?
f) Normal working hours
g) Duties of Fire Safety Director {see E-9.1)
E-8.4 Deputy Fire Safety Director
a) Name
b) Regularly assigned employment — Title
c) Regularly assigned location
d) How is he notified when at regular location?
e) How is he notified when not at regular
location?
f) Normal working hours
g) Duties of Deputy Fire Safety Director
{see E-9.2)
E-8.5 Fire Wardens and Deputy Fire Wardens
a) Are their names on Organization Charts for
each floor and/or tenancy?
b) Submit typical completed Organization Chart
for Fire Drill and Evacuation Assignment.
c) Duties of Fire Wardens and Deputy Fire
Wardens {see E-9.3).
E-8.6 Building Evacuation Supervisor
a) Name
b) Regularly assigned employment — Title
c) Regularly assigned location
d) How is he notified when at regular location?
e) How is he notified when not at regular location?
f) Normal working hours
g) Duties of Building Evacuation Supervisor
{see E-9.4).
E-8.7 Fire Party
a) Submit a completed Organization Chart for
Fire Parties naming person in charge, and his
title in the building.
b) Indicate standards of selection from building
employees based on background and
availability.
78
NATIONAL BUILDING CODE OF INDIA
c) How are they notified?
d) How are they notified when they are not at
their regular locations?
e) Means of responding
f) Duties of each member of Fire Party
(see E-9.5).
E-8.8 Occupants Instructions
Distribution of instructions to all tenants, tenents'
employees and building employees (see E-9.6).
E-8.9 Evacuation Drills
a) Frequency of drills
b) How conducted?
c) Participation: Who participated? How?
d) Controls and supervision
e) Recording of details of drills
E-8.10 Fire Command Station
a) Location
b) Requirements
1) Adequate illumination
2) Adequate communication to mechanical
equipment room and elevator control
room on each floor
3) Copy of Fire Safety Plan
4) Copy of Building Information Form
5) Representative floor plans showing
location of signs, floor remote station,
communications, etc.
E-8.11 Signs
a) Signs at elevator landings, Floor diagrams
b) Floor numbering
c) Stairway identification
d) Elevator identification
e) Stair re-entry
E-8.12 Fire Prevention and Fire Protection
Programme (see E- 9.7).
E-8.13 Building Information Form (see E-9.8).
E-8.14 Representative Floor Plan (see E-9.9).
E-8.15 Fire Safety Plan Prepared by (see E-9.10).
a) Date when prepared.
b) Date when revised.
E-9 DUTIES
E-9.1 Fire Safety Director's Duties
E-9.1.1 Be familiar with the written Fire Safety Plan
providing for fire drill and evacuation procedure in
accordance with orders on the subject.
E-9.1.2 Select qualified building service employees
for a Fire Party and organize, train and supervise such
Fire Brigade.
E-9.1.3 Be responsible for the availability and state
of readiness of the Fire Party.
E-9.1.4 Conduct fire and evacuation drills.
E-9.1.5 Be responsible for the designation and training
of a Fire Warden for each floor, and sufficient Deputy
Fire Wardens for each tenancy in accordance with
orders on the subject.
E-9.1.6 Be responsible for a daily check for the
availability of the Fire Wardens, and see that up-to-
date organization charts are posted.
NOTE — If the number of Fire Wardens and Deputy Fire
Wardens in the building is such that it is impractical to
individually contact each one daily, a suggested method to
satisfy the requirements is to make provisions for the Fire
Warden, or a Deputy Fire Warden in the absence of the Fire
Warden, to notify the Fire Safety Director when the Fire
Warden or required number of Deputy Fire Wardens are not
available. In order to determine the compliance by the Fire
Warden and Deputy Fire Wardens, when this method is used,
the Fire Safety Director shall make a spot check of several
different floors each day.
E-9.1.7 Notify the owner or some other person having
charge of the building when any designated individual
is neglecting his responsibilities contained in Fire
Safety Plan. The owner or the other person in-charge
of the building shall bring the matter to the attention
of the firm employing the individual. If the firm fails
to correct the condition, the Fire Department shall be
notified by the owner/person in-charge of the building.
E-9,1.8 In the event of fire, shall report to the Fire
Command Station to supervise, provide for and
coordinate:
a) Ensure that the Fire Department has been
notified of any fire or fire alarm.
b) Manning of the Fire Command Station.
c) Direction of evacuating procedures as
provided in the Fire Safety Plan.
d) Reports on conditions on fire floor for
information of Fyee Department on their
arrival.
e) Advise the Fire Department Officer in-charge
in the operation of the Fire Command Station.
E-9.1.9 Be responsible for the training and activities
of the Building Evacuation Supervisor.
E-9.2 Deputy Fire Safety Director's Duties
E-9.2.1 Subordinate to the Fire Safety Director.
E-9.2.2 Perform duties of Fire Safety Director in his
absence.
PART 4 FIRE AND LIFE SAFETY
79
E-9.3 Fire Wardens and Deputy Fire Wardens
Duties
The tenant or tenants of each floor shall, upon request
of the owner or person in charge of buildings, make
responsible and dependable employees available for
designation by the Fire Safety Director as Fire Warden
and Deputy Fire Wardens.
E-9.3.1 Each floor of a building shall be under the
direction of a designated Fire Warden for the
evacuation of occupants in the event of fire. He shall
be assisted in his duties by the Deputy Fire Wardens.
A Deputy Fire warden shall be provided for each
tenancy. When the floor area of a tenancy exceeds
700 m 2 of occupiable space, a Deputy Fire Warden
shall be assigned for each 700 m 2 or part thereof.
E-9.3.2 Each Fire Warden and Deputy Fire Warden
shall be familiar with the Fire Safety Plan, the location
of exits and the location and operation of any available
fire alarm system.
E-9.3.3 In the event of fire, or fire alarm the Fire
Warden shall ascertain the location of the fire, and
direct evacuation of the floor in accordance with
directions received and the following guidelines:
a) The most critical areas for immediate
evacuation are the fire floor and floors
immediately above.
Evacuation from the other floors shall be
instituted when instructions from the Fire
Command Station or conditions indicate such
action. Evacuation shall be via uncontaminated
stairs. The Fire Warden shall try to avoid
stairs being used by the Fire Department. If
this is not possible, he shall try to attract the
attention of the Fire Department Personnel
before such personnel open the door to the
fire floor.
b) Evacuation to two or more levels below the
fire floor is generally adequate. He shall keep
the Fire Command Station informed regarding
his location.
c) Fire Wardens and their Deputies shall see that
all occupants are notified of the fire, and that
they proceed immediately to execute the Fire
Safety Plan.
d) The Fire Warden on the fire floor shall, as
soon as practicable, notify the Fire Command
Station of the particulars.
e) Fire Wardens on floors above the fire shall,
after executing the Fire Safety Plan, notify
the Fire Command Station of the means being
used for evacuation and any other particulars.
f) In the event that stairways serving fire floor
and/or floors above are unusable due to
contamination or cut off by fire and/or smoke
or that several floors above fire involve
large numbers of occupants who must be
evacuated, consideration may be given to
using elevators in accordance with the
following:
1) If the elevators servicing his floor also
service the fire floor, they shall not be
used. However, elevators may be used if
there is more than one bank of elevators,
and he is informed from the Fire Command
Station that one bank is unaffected by the
fire.
2) If elevators do not service the fire floor
and their shafts have no openings on the
fire floor, they may be used, unless
directed otherwise.
3) Elevators manned by trained building
personnel or firemen may also be used.
4) In the absence of a serviceable elevator,
the Fire Warden shall select the safest
stairway to use for evacuation on the
basis of the location of the fire and any
information received from the Fire
Command Station. The Fire Warden shall
check the environment in the stairs prior
to entry for evacuation. If it is affected
by smoke, alternative stair shall be
selected, and the Fire Command Station
notified.
5) The Fire Warden shall keep the Fire
Command Station informed of the means
being employed for evacuation by the
occupants of his floor.
g) Ensure that an alarm has been transmitted.
E-9.3. 4 Organization Chart for Fire Drill and
Evacuation Assignment
A chart designating employees and their assignments
shall be prepared and posted in a conspicuous place in
each tenancy and on each floor of a tenancy that
occupies more than one/floor and a copy shall be in
the possession of the Fire Safety Director.
E-9.3.5 Keep available an updated listing of all
personnel with physical disabilities who cannot use stairs
unaided. Make arrangements to have these occupants
assisted in moving down the stairs to two or more levels
below fire floor. If it is necessary to move such occupants
to a still lower level during the fire, move them down
the stairs to the uppermost floor served by an uninvolved
elevator bank and then remove them the street floor by
elevator. Where assistance is required for such
evacuation, notify Fire Safety Director.
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NATIONAL BUILDING CODE OF INDIA
E-9.3.6 Provide for Fire Warden identification during
fire drills and fires, such as using armband, etc.
E-9.3.7 Ensure that all persons on the floor are notified
of fire and all are evacuated to safe areas. A search
must be conducted in the lavatories to ensure all are
out. Personnel assigned as searchers can promptly and
efficiently perform this duty.
E-9.3.8 Check availability of applicable personnel on
Organization Chart and provide for a substitute when
the position on a chart is not covered.
E-9.3.9 After evacuation, perform a head count to
ensure that all regular occupants known to have
occupied the floor have been evacuated.
E-9.3.10 When alarm is received, the Fire Warden
shall remain at a selected position in the vicinity of the
communication station on the floor, in order to
maintain communication with the Fire Command
Station and to receive and give instructions.
E-9.4 Building Evacuation Supervisor's Duties
A building Evacuation Supervisor is required at all
times other than normal working or business hours
when there are occupants in the building and there is
no Fire Safety Director on duty in the building.
E-9.4. 1 He should be capable of directing the
evacuation of the occupants as provided by the Fire
Safety Plan.
E-9.4. 2 During fire emergencies, the primary
responsibility of the Building Evacuation Supervisor
shall be to man the Fire Command Station, and the
direction and execution of the evacuation as provided
in the Fire Safety Plan. The Building Evacuation
Supervisor's training and related activities shall be
under the direction of the Fire Safety Director in
accordance with these rules, and the Fire Safety Plan.
Such activities shall be subject to Fire Department
control.
E-9.5 Fire Party Duties
On receipt of an alarm for fire the Fire Party shall:
a) report to the floor below the fire to assit in
evacuation and provide information to the
Fire Command Station.
b) after evacuations of fire floor, endeavour to
control spread of fire by closing doors, etc.
c) attempt to control the fire until arrival of the
Fire Department, if the fire is small and
conditions do not pose a personal threat.
d) leave one member on the floor below the fire
to direct the Fire Department to the fire
location and to inform them of conditions.
e) on arrival of the Fire Department, the Fire
Party shall report to the Fire Command Station
for additional instructions.
f) have a member designated as runner, who
shall know the location of the nearest
telephone, and be instructed in its use. Such
member shall immediately upon receipt of
information that there is a fire or evidence of
fire, go to the telephone, transmit an alarm
and await the arrival of the Fire Department
and direct such department to the fire.
NOTE — A qhart designating employees and their
assignments shall be prepared.
E-9.6 Occupant's Instructions
a) The applicable parts of the approved Fire
Safety Plan shall be distributed to all tenants
of the building by the building management
when the Fire Safety Plan has been approved
by the Fire Commissioner.
b) The applicable parts of the approved Fire
Safety Plan shall then be distributed by the
tenants to all their employees and by the
building management to all their building
employees.
c) All occupants of the building shall participate
and cooperate in carrying out the provisions
of the Fire Safety Plan.
E-9.7 Fire Invention and Fire Protection Programme
a) A plan for periodic formal inspections of each
floor area, including exit facilities, fire
extinguishers and house keeping shall be
developed. A copy of such plan be submitted.
b) Provision shall be made for the monthly
testing of communication and alarm systems.
E-9.8 Building Information Form
It shall include the following information:
a) Building address.. Pin Code
b) Owner or person in-charge of building —
Name, Address and Telephone Number.
c) Fire Safety Director and Deputy Fire Safety
Director's Name and Telephone Number.
d) Certificate of occupancy. Location where
posted, or duplicate attached.
e) Height, area, class of construction.
f) Number, type and location of fire stairs and/
or fire towers.
g) Number, type and location of horizontal exits
or other areas of refuge.
h) Number, type, location and operation of
elevators and escalators.
PART 4 FIRE AND LIFE SAFETY
81
j) Interior fire alarms, or alarms to central
stations,
k) Communications systems and/or walkie
talkie, telephones, etc.
m) Standpipe system; size and location of risers,
gravity or pressure tank, fire pump, location
of Siamese connections, name of employee
with certificate of qualification and number
of certificate,
n) Sprinkler system; name of employee with
Certificate of Fitness and certificate number.
Primary and secondary water supply, fire
pump and areas protected,
p) Special extinguishing system, if any,
components and operation,
q) Average number of persons normally employed
in building. Daytime and night time,
r) Average number of handicapped people in
building. Location. Daytime and night time.
s) Number of persons normally visiting the
building. Daytime and night time,
t) Service equipment such as:
1) Electric power, primary, auxiliary;
2) Lighting, normal, emergency, type and
location;
3) Heating, type, fuel, location of heating
unit;
4) Ventilation — with fixed windows,
emergency means of exhausting heat and
smoke;
5) Air-Conditioning Systems — Brief
description of the system, including ducts
and floors serviced;
6) Refuse storage and disposal;
7) Fire fighting equipment and appliances,
other than standpipe and sprinkler
system; and
8) Other pertinent building equipment.
u) Alterations and repair operations, if any, and
the protective and preventive measures
necessary to safeguard such operations with
attention to torch operations,
v) Storage and use of flammable solids, liquids
and/or gases,
w) Special occupancies in the building and the
proper protection and maintenance thereof.
Places of public assembly, studios, and
theatrical occupancies.
E-9.9 Representative Floor Plan
A floor plan, representative of the majority or the floor
designs of the entire building, shall be at the Command
Post, in the main lobby, under the authority of the Fire
Safety Director. One copy of a representative floor plan
shall be submitted to the Fire Department with the Fire
Safety plan.
E-9.10 Fire Safety Plan
In planning, evaluate the individual floor layouts, the
population of floors, the number and kinds of exits,
the zoning of the floor by area and occupants.
Determine the movement of traffic by the most
expeditious route to an appropriate exit and alternative
route for each zone, since under fire conditions one or
more exits may not be usable. This format is to be used
in the preparation of the Fire Safety Plan. Nothing
contained in this Fire Safety Plan format is to be
construed as all inclusive. All rules and other
requirements are to be fully complied with.
E-9.11 Personal Fire Instruction Card
All the occupants of the building shall be given a
Personal Fire Instruction Card giving the details of the
floor plan and exit routes along with the instruction to
be followed in the event of fire. A typical Personal
Fire Instruction Card shall be as follows:
PERSONAL FIRE
INSTRUCTION CARD
SEAL
NAME OF THE ORGANIZATION
ADDRESS OF THE ORGANIZATION
NAME:
DESIGNATION:
FLOOR NO.:
DATE:
FIRE WARDEN
INSTRUCTIONS
FOR YOUR OWN SAFETY YOU SHOULD KNOW
1. Two push button fire alarm boxes are
provided per floor. You should read the
operating instructions.
2. You should read the operating instructions on
the body of the fire extinguishers provided
on your floor.
3. The nearest exit from your table.
4. Your assembly point on ground floor (check
with your Fire/Deputy Fire Warden).
5. FOR YOUR OWN PROTECTION YOU
SHOULD REPORT TO YOUR FIRE/
DEPUTY FIRE WARDEN
82
NATIONAL BUILDING CODE OF INDIA
a) If any exit door/route is obstructed by loose
materials, goods, boxes, etc.
b) If any staircase door, lift lobby door does not
close automatically, or does not close
completely.
c) If any push button fire alarm point, or fire
extinguisher is obstructed, damaged or
apparently out of order.
IF YOU DISCOVER A FIRE
1 . Break the glass of the nearest push button fire
alarm and push the button.
2. Attack the fire with extinguishers provided on
your floor. Take guidance from your Wardens.
3. Evacuate if your Warden asks you to do so.
IF YOU HEAR EVACUATION INSTRUCTIONS
1.
Leave the floor immediately by the south/
north staircase.
Report to your Warden, at your predetermined
assembly point outside the building.
Do not try to use lifts.
Do not go to cloakroom.
Do not run or shout.
Do not stop to collect personal belongings.
Keep the lift lobby and staircase doors shut.
YOUR ASSEMBLY POINT IS
2.
3.
4.
5.
6.
7.
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and 'accepted standards'
in the fulfillment of the requirements of the Code. The
standards listed may be used by the Authority as a guide
in conformance with the requirements of the referred
clauses in the Code.
IS No.
(1) 3808: 1979
(2) 8757 : 1999
7673 : 1975
(3) 15394:2003
(4) 8758 : 1993
(5) 3809 : 1979
1641 : 1988
15103:2002
(6) 9668 : 1990
Title
Method of test for non-
combustibility of building
materials (first revision)
Glossary of terms associated
with fire safety {first revision)
Glossary of terms for fire
fighting equipment
Fire safety in petroleum refinery
and fertilizer plants — Code of
practice
Recommendations for fire
precautionary measures in the
construction of temporary
structures and PANDALS (first
revision)
Fire resistance test of structure
(first revision)
Code of practice for fire safety
of buildings (general): General
principles of fire grading and
classification (first revision)
Specification for fire resistant
steel
Code of practice for provision
and maintenance of water
supplies and fire fighting
IS No.
3844 : 1989
(7) 3614
(Part 1) : 1966
(8) 12458 : 1988
(9) 1646 : 1997
2309 : 1989
(10)
(11) 11360:1985
(12) 659 : 1964
(13) 1649:1962
1642 : 1989
(14) 12777 : 1989
Title
Code of practice for installation
and maintenance of internal fire
hydrants and hose reels on
premises (first revision)
Specification for fire check
doors: Part 1 Plate, metal covered
and rolling type
Method of test for fire resistance
test for fire stops
Code of practice for fire safety
of buildings (general) :
Electrical installations (second
revision)
Code of practice for protection of
building and allied structures
against lighting (second revision)
Specification for fire dampers
for air conditioning ducts (under
preparation)
Specification for smoke
detectors for use in automatic
electrical fire alarm system
Safety code for air-conditioning
Code of practice for design and
construction of flues and
chimneys for domestic heating
appliances (first revision)
Code of practice for safety of
buildings (general): Details of
construction (first revision)
Fire safety-flame-spread of
products — Method for
classification
PART 4 FIRE AND LIFE SAFETY
83
IS No.
(15) 1642 : 1989
1643 : 1988
1644 : 1988
(16)9457: 1980
12349 : 1988
12407 : 1988
(17)2175: 1988
11360: 1985
(18)2189 : 1999
(19) 636 : 1988
884 : 1985
901 : 1988
902 : 1992
903 : 1993
904 : 1983
905 : 1980
Title
Code of practice for fire safety
of buildings (general): Details of
construction (first revision)
Code of practice for fire safety
of buildings (general): Exposure
hazard (first revision)
Code of practice for fire safety
of buildings (general): Exit
requirements and personal
hazard (first revision)
Safety colours and safety signs
Fire protection — Safety sign
Graphic symbols for fire
protection plan
Specification for heat sensitive
fire detectors for use in
automatic fire alarm system
(second revision)
Specification for smoke
detectors for use in automatic
electrical fire alarm system
Code of practice for selection,
installation and maintenance of
automatic fire detection
and alarm system (second
revision)
Non-percolating flexible fire
fighting delivery hose (third
revision)
Specification for first-aid hose
reel for fire fighting (first
revision)
Specification for couplings,
double male and double female
instantaneous pattern for fire
fighting (third revision)
Specification for suction hose
couplings for fire fighting
purposes (third revision)
Specification for fire hose
delivery couplings, branch pipe,
nozzles and nozzle spanner
(fourth revision)
Specification for two-way and
three-way suction collecting
heads for fire fighting purposes
(second revision)
Specification for delivery
breechings, dividing and
collecting, instantaneous pattern
for fire fighting purposes (second
revision)
IS No. Title
906 : 1988 Specification for revolving
branch pipe for fire fighting
(third revision)
907 : 1984 Specification for suction
strainers, cylindrical type for fire
fighting purpose (second revision)
908 : 1975 Specification for fire hydrant,
stand post type (second revision)
909 : 1992 Specification for underground
fire hydrant: Sluice valve type
(third revision)
910 : 1980 Specification for combined key
for hydrant, hydrant cover and
lower valve (second revision)
926 : 1985 Specification for fireman's axe
(second revision)
927 : 1981 Specification for fire hooks
(second revision)
928 : 1984 Specification for fire bells
(second revision)
937 : 1981 Specification for washers for
water fittings for fire fighting
purposes (second revision)
939 : 1977 Specification for snatch block
for use with fibre rope for fire
brigade use (first revision)
940 : 1989 Specification for portable fire
extinguisher, water type (gas
cartridge) (third revision)
941 : 1985 Specification for blowers and
exhauster for fire fighting
(second revision)
942 : 1982 Functional requirements for 275-
1/min portable pump set for fire
fighting (second revision)
943 : 1979 Functional requirement for 680-
1/min trailer pump for fire
brigade use (second revision)
944 : 1979 Functional requirement for
1800-1/min trailer pump for fire
brigade use (second revision)
947 : 1985 Functional requirement for
towing tender for trailer fire
pump for fire brigade use (first
revision)
948 : 1983 Functional requirement for water
tender, Type A, for fire brigade
use (second revision)
949 : 1985 Functional requirement for
emergency (rescue) tender for fire
brigade use (second revision)
84
NATIONAL BUILDING CODE OF INDIA
IS No.
950:
: 1980
952:
1986
955:
1980
957 : 1967
1941
(Part 1) : 1976
2097 : 1983
2171 : 1999
2175 : 1988
2298 : 1977
2546 : 1974
2696 : 1974
2745 : 1983
2871 : 1983
2878 : 2004
2930 : 1980
3582 : 1984
Title
Functional requirements
for water tender, Type B for fire
brigade use (second revision)
Specification for foghnozzle for
fire brigade use (first revision)
Functional requirements for dry
power tender for fire-brigade
use (150 kg capacity) (first
revision)
Specification for control van for
fire brigade
Functional requirements for
electric motor sirens: Part 1 ac 3
phase 50Hz, 415 V type (second
revision)
Specification for foam making
branch pipe (first revision)
Specification for portable fire
extinguishers, dry powder
(cartridge type) (third revision)
Specification for heat sensitive
fire detectors for use in
automatic detectors for use in
automatic fire alarm system
(second revision)
Specification for single-barrel
stirrup pump for fire fighting
purposes (second revision)
Specification for galvanized
mild steel fire bucket (first
revision)
Functional requirements for
1 125 1/min light fire engine
(first revision)
Specification for non-metal
helmet for firemen and civil
defence personnel (second
revision)
Specification for branch pipe,
universal for fire fighting
purposes (first revision)
Specification for fire
extinguisher, carbon-dioxide
type (portable and trolley
mounted) (third revision)
Functional requirements for
hose laying tender for fire
brigade use (first revision)
Specification for basket strainers
for fire fighting purposes
(cylindrical type) (first revision)
IS No.
4308 : 1982
4571 : 1977
4643 : 1984
4861 : 1984
4927 : 1992
4928 : 1986
4947 :^985
4989
(Part 1) : 2004
4989
(Part 2) : 1984
(Part 3) : 1987
5131 : 1986
5290 : 1993
5486 : 1985
5505 : 1985
5612
(Part 1) : 1977
(Part 2) : 1977
5714: 1981
Title
Specification for dry powder for
fire fighting (first revision)
Specification for aluminium
extension ladders for fire brigade
use (first revision)
Specification for suction
wrenches for fire brigade use
(first revision)
Specification for dry powder for
fighting fires in burning metals
(first revision)
Specification for unlined flax
canvas hose for fire fighting
(first revision)
Specification for delivery valve
for centrifugal pump outlets
(first revision)
Specification for gas cartridges
for use in fire extinguishers
(second revision)
Specifications for multipurpose
aqueous film forming foam
liquid concentrate for
extinguishing hydrocarbon
and polar solvent fires (third
revision)
Specification for foam concentrate
(compound) for producing
mechanical foam for fire
fighting: Part 2 Aqueous film
forming foam (AFFF)
Ruoro protein foam
Specification for dividing
breeching with control, for fire
brigade use (first revision)
Specification for landing valve
(third revision)
Specification for quick release
knife (first revision)
Specification for multi-edged
rescue axe (non-wedging) (first
revision)
Specification for hose-clamps
and hose-bandages for fire
brigade use:
Hose clamps (first revision)
Hose bandages (first revision)
Specification for hydrant, stand-
pipe for fire fighting (first
revision)
PART 4 FIRE AND LIFE SAFETY
85
IS No. Title
6026 : 1985 Specification for hand-operated
sirens (first revision)
6067 : 1983 Functional requirements for
water tender, Type 'X' for fire
brigade use (first revision)
6234 : 1986 Specification for portable fire
extinguishers, water type (stored
pressure) (first revision)
8090: 1992 Specification for couplings,
branch pipe, nozzle, used in hose
reel tubing for fire righting (first
revision)
8096 : 1992 Specification for fire beaters
(first revision)
8 1 49 : 1 994 Functional requirements for twin
C0 2 fire extinguishers (trolley
mounted) (first revision)
8423 : 1994 Specification for controlled
percolating hose for fire fighting
(first revision)
8442 : 1 977 Specification for stand post type
water monitor for fire fighting
9972 : 1981 Specification for automatic
sprinkler heads
10204 : 1982 Specification for portable fire
extinguisher mechanical foam
type
10460: 1983 Functional requirements for
small foam tender for fire
brigade use
10658 : 1999 Specification for higher capacity
dry powder fire extinguisher
(trolley mounted)
10993 : 1984 Functional requirements for
2000 kg dry powder tender for
fire brigade us
11070: 1984 Specification for bromo
chlorodifluoromethane (Halon-
1211) for fire fighting
111.01 : 1984 Specification for extended
branch pipe for fire brigade
use
11108 : 1984 Specification for portable fire
extinguisher halon- 12 11 type
11360: 1985 Specification for smoke
detectors for use in automatic
electrical fire alarm systems
11833 : 1986 Specification for dry powder
fire extinguisher for metal
fires
IS No. Title
12717 : 1989 Functional requirements of fire
fighting equipment — High
capacity portable pumpset
(1 100-1 600 1/min)
12796 : 1989 Specification for fire rake
13039 : 1991 Code of practice for provision
and maintenance of external
hydrant system
13385 : 1992 Specification for fire
extinguisher 50 capacity wheel
mounted water type (gas
cartridge)
13386 : 1992 Specification for 50 litre capacity
fire extinguisher, mechanical
foam type
13849 : 1993 Specification for portable fire
extinguisher dry powder type
(constant pressure)
14609 : 1999 Specification for ABC dry
powder for fire fighting
14933 : 2001 Specification for high pressure
fire fighting hose
14951 : 2001 Specification for fire
extinguisher, 135 litre capacity
mechanical foam type
15051 : 2002 Specification for high pressure
fire hose delivery couplings
15105 : 2002 Design and installation of
fixed automatic sprinkler fire
extinguishing system
15220 : 2002 Specification for halon 121 1 and
halon 1301 — Fire extinguishing
media for fire protection
15493 : 2004 Gaseous fire extinguishing
systems — General requirements
15497 : 2004 Specification for gaseous fire
extinguishing system — IG 01
extinguishing system
15501 : 2004 Specification for gaseous fire
extinguishing system — IG 541
extinguishing system
15505 : 2004 Gaseous fire extinguishing
systems — HCFC blend A
extinguishing systems
15506 : 2004 Specification for inert gaseous
total fire protection total flooding
system — Argonite, IG 55
extinguishing system
15517 : 2004 Gaseous fire extinguishing
systems — HFC 227 (heptafluoro
propane) extinguishing system
86
NATIONAL BUILDING CODE OF INDIA
IS No.
15519 : 2004
15525 : 2004
15528 : 2004
(20) 2190 : 1992
(21)884: 1985
15517 :2004
(22) 3034 : 1993
(23) 6382 : 1984
(24) 14609 : 2001
15493 : 2004
(25) 13716: 1993
(26) 4963 : 1987
(27) 4878 : 1986
(28) 12456 : 1988
(29) 1646: 1997
2726 : 1988
Title
Code of practice for water mist
fire protection systems —
System design, installation and
commissioning
Specification for gaseous fire
extinguishing system — IG 100
extinguishing system
Gaseous fire extinguishing
systems — Carbon dioxide, total
flooding and local application
(sub-flour and in-cabinet), high
and low pressure (refrigerated)
systems
Code of practice for selection,
installation and maintenance
of portable first-aid fire
extinguishers (third revision)
Specification for first-aid hose
reel for fire fighting (first revision)
Code of practice for inspection
and maintenance of gaseous fire
extinguishing systems
Code of practice for fire safety
of industrial buildings: Electrical
generating and distributing
stations (second revision)
Code of practice for design and
installation of fixed carbon
dioxide fire extinguishing
system (first revision)
Specification for dry powder for
fire fighting — Class ABC fires
General requirement for
commissioning of gaseous fire
extinguishing systems
Code of practice for fire safety
in hotels
Recommendations for buildings
and facilities for the physically
handicapped (first revision)
Bye-laws for construction of
cinema buildings (first revision)
Code of practice for fire
protection of electronic data
processing installations
Code of practice for fire safety
of buildings (general) :
Electrical installations (second
revision)
Code of practice for fire safety
of industrial buildings: Cotton
IS No, Title
ginning and pressing (including
cotton seed delintering) factories
(first revision)
3034 : 1993 Code of practice for fire safety
of industrial buildings: Electrical
generating and distributing
stations (second revision)
3058 : 1990 Code of practice for fire safety
of industrial buildings: Viscose
rayon yarn and/or staple fibre
plants (first revision)
3079 : 1990 Code of practice for fire safety
of industrial buildings: Cotton
textile mills (first revision)
3594 : 1991 Code of practice for fire safety
of industrial buildings: General
storage and warehousing
including cold storage (first
revision)
3595 : 1984 Code of practice for fire safety
of industrial buildings: Coal
pulverizers and associated
equipment (first revision)
3836 : 2000 Code of practice for fire safety
of industrial buildings: Jute
mills (second revision)
4209 : 1987 Code of safety in chemical
laboratories (first revision)
4226 : 1988 Code of practice for fire safety of
industrial buildings: Aluminium/
Magnesium powder factories
(first revision)
4886 : 1991 Code of practice for fire safety
of industrial buildings: Tea
factories (first revision)
6329 : 2000 Code of practice for fire safety
of. industrial buildings: Saw
mills and wood works (first
revision)
9109 : 2000 Code of practice for fire safety
of industrial buildings: Paint and
varnish factories
11457 Code of practice for fire safety
(Part 1) : 1985 of chemical industries: Part 1
Rubber and plastic
1 1460 : 1985 Code of practice for fire safety of
libraries and archives buildings
12349 : 1988 Fire protection — Safety signs
12407 : 1988 Graphic symbols for fire
protection plans
PART 4 FIRE AND LIFE SAFETY
87
IS No. Title
12456:1988 Code of practice for fire
protection of electronic data
processing installation
12458 : 1988 Method of test for fire resistance
test of fire stops
12459 : 1988 Code of practice for fire-
protection of cable runs
12777 : 1989 Fire safety — Flame spread of
products — Method for
classification
13045 : 1991 Code of practice for fire safety
in industrial buildings: Floor
mills
IS No.
13694 :
1993
13716 : 1993
14435 : 1997
14689 : 1999
14850 : 2000
(30) 655 : 1963
(31)9583: 1981
Title
Code of practice for fire safety
in iron and steel industries
Code of practice for fire safety
of hotels
Code of practice for fire safety
in educational institutions
Code of practice for fire safety in
printing and publishing industry
Code of practice for fire safety
of museums
Specification for metal air ducts
(revised)
Emergency lighting units
88
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 5 BUILDING MATERIALS
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 MATERIALS
3 NEW OR ALTERNATIVE MATERIALS
4 THIRD PARTY CERTIFICATION
5 USED MATERIALS
6 STORAGE OF MATERIALS
7 METHODS OF TEST
LIST OF STANDARDS
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
Ensuring the quality and effectiveness of building materials used in the construction and their storage are as
important as the other phases of building activity like planning, designing and constructing the building itself.
This Part, therefore, lists Indian Standards for materials used in building construction. The methods of tests, to
ensure the requirements demanded of the materials in the various situations, are also included.
Historically choice of building materials was determined by what was locally available, appropriateness to geo-
climatic conditions and affordability of users. In recent past, different initiatives have been taken in the areas of
research and development, standardization, and development and promotion of innovative materials. A review
of the recent trends indicates that the growth in the area of building materials covers emerging trends and latest
developments in the use of wastes, mineral admixtures in cement and concrete, substitutes to conventional timber,
composite materials and recycling of wastes, at the same time ensuring desired response of materials to fire, long
term performance and durability. In addition to these developments, the future decade may witness development
of specific materials which may be structured and designed to meet needs to specially developed construction
technologies, such as, for disaster prone areas or aggressive climatic and industrial situations.
In this context, the following factors have become important for facilitating application and adoption in practice,
of the materials:
a) Utilization of industrial, mining, mineral and agricultural wastes; plantation timbers; and renewable
natural fibres and residues for production of building materials.
b) Impact of production of building materials on the consumption levels of natural resources.
c) Change in energy demand in production of building materials due to development of efficient
manufacturing processes.
d) Impact of production and usage of materials and disposal thereof on the environment.
To encourage use of appropriate materials, it may be desirable to have, to the extent possible, performance
oriented approach for specifications rather than prescriptive approach. The approach has been already adopted in
some cases in development of standards, wherever found possible.
Indian Standards cover most of the requirements for materials in use. However, there may be a gap between
development of new materials and techniques of application and formulation of standards. It, therefore, becomes
necessary for a Building Code to be flexible to recognize building materials other than those for which Indian
Standards are available. This Part, therefore, since its first version, duly takes care of this aspect and explicitly
provides for use of new or alternate building materials, provided it is proved by authentic tests that the new or
alternative material is effective and suitable for the purpose intended. However, it is worthwhile that more and
more emphasis is given to the satisfaction of performance requirements expected of a building material, so that
a wide range of such new or alternate materials can be evaluated and used, if found appropriate.
As already emphasized, quality of material is quite important for their appropriate usage, whether it is a material
for which an Indian Standard is available or a new or alternative material as defined in 3 of this Part. Third party
certification schemes available in the country for quality assurance of above materials can be used with advantage
to ensure the appropriateness of these materials.
This Part of the Code was first published in 1970 and subsequently revised in 1983. The first revision of this Part
incorporated an updated version of the list of Indian Standards given at the end of this Part of the Code. The
present draft revision of this Part, while basically retaining the structure of 1983 version of the Code, explicitly
takes care of the following:
a) While continuing to emphasize on conformity of building materials to available Indian Standards, the
building regulating authority also recognizes use of building materials conforming to other specifications
and test methods (see 3), in case Indian Standards are not available for particular materials.
PART 5 BUILDING MATERIALS 3
b) The list at the end of this part has been completely reclassified to make it more user friendly and
updated to reflect the latest available Indian Standard and methods of test.
A reference to SP 21 'Summaries of Indian Standards for building materials' may be useful. This publication
gives the summaries of Indian Standards covering various building materials, fittings and components except
standards relating to paints.
All standards cross-referred to in the main text of this Part, are subject to revision. The parties to agreement
based on this section are encouraged to investigate the possibility of applying the most recent editions of the
standards.
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 5 BUILDING MATERIALS
1 SCOPE
This Part of the Code covers the requirements of building
materials and components, and criteria for accepting new
or alternative building materials and components.
2 MATERIALS
Every material used in fulfilment of the requirements
of this Part, unless otherwise specified in the Code or
approved, shall conform to the relevant Indian Standards.
A list of Indian Standards as the 'accepted standards' is
given at the end of this Part of the Code. At the time of
publication of the Code, the editions indicated were
valid. All standards are subject to amendments and
revisions. The Authority shall take cognizance of such
amendments and revisions. The latest version of a
standard shall, as far as possible, be adopted at the time
of enforcement of this Part of the Code.
3 NEW OR ALTERNATIVE MATERIALS
3.1 The provisions of this Part are not intended to
prevent the use of any material not specifically
prescribed under 2. Any such material may be approved
by the Authority or an agency appointed by them for
the purpose, provided it is established that the material
is satisfactory for the purpose intended and the
equivalent of that required in this Part or any other
specification issued or approved by the Authority, The
Authority or an agency appointed by them shall take
into account the following parameters, as applicable
to the concerned new or alternative building material:
a) Requirements of the material specified/
expected in terms of the provisions given in
the standards on its usage, including its
applicability in geo-climatic condition;
b) General appearance;
c) Dimension and dimensional stability;
d) Structural stability including strength properties;
e) Fire safety;
f) Durability;
g) Thermal properties;
h) Mechanical properties;
j) Acoustical properties;
k) Optical properties ;
m) Biological effect;
n) Environmental aspects;
p) Working characteristics;
q) Ease of handling; and
r) Consistency and workability.
For establishing the performance of the material/
component, laboratory/field tests, and field trials, as
required, and study of historical data are recommended.
3.2 Approval in writing of the Authority or an agent
appointed by them for the purpose of approval of
material, shall be obtained by the owner or his agent
before any new, alternative or equivalent material is
used. The Authority or their agent shall base such
approval on the principle set forth in 3.1 and shall
require that tests be made (see 7.1) or sufficient
evidence or proof be submitted, at the expense of the
owner or his agent, to substantiate any claim for the
proposed material.
NOTE — For interpretation of the term 'Authority' {see
also 7.1), the definition of 'Authority having jurisdiction' given
in Part 2 'Administration' shall apply.
4 THIRD PARTY CERTIFICATION
For ensuring the conformity of materials for which
Indian Standards exist and for new or alternative
building materials, to requisite quality parameters the
services under the third party certification schemes of
the Government, may be utilized with advantage.
5 USED MATERIALS
The use of used materials may not be precluded
provided these meet the requirements of this Part for
new materials (see Part 2 'Administration').
6 STORAGE OF MATERIALS
All building materials shall be stored on the building
site in such a way as to prevent deterioration or the
loss or impairment of their structural and other essential
properties (see Part 7 'Constructional Practices and
Safety').
7 METHODS OF TEST
7.1 Every test of material required in this Part or by
the Authority shall be carried out in accordance with
the Indian Standard methods of test. In the case of
methods of tests where Indian Standards are not
available, the same shall conform to the methods of
tests issued by the Authority or their agent. A list of
Indian Standard methods of test is given at the end of
this Part of the Code as the 'good practices' . Laboratory
tests shall be conducted by recognized laboratories
acceptable to the Authority.
7.1.1 The manufacturer/supplier shall satisfy himself
that materials conform to the requirements of the
specifications and if requested shall supply a certificate
to this effect to the purchaser or his representative.
When such test certificates are not available, the
specimen of the material shall be tested.
PART 5 BUILDING MATERIALS
LIST OF STANDARDS
Following are the Indian Standards for various building
materials and components, to be complied with in
fulfillment of the requirements of the Code.
In the following list, while enlisting the Indian
Standards, the materials have been categorized in such
a way as to make the list user friendly. In the process,
if so required, some of the standards have been included
even in more than one category of products, such as in
the category based on composition as well as on end
application of the materials. The list has been arranged
in alphabetical order of their principal category as given
below:
1. ALUMINIUM AND OTHER LIGHT METALS
AND THEIR ALLOYS
2. BITUMEN AND TAR PRODUCTS
3. BUILDER'S HARDWARES
4. BUILDING CHEMICALS
5. BUILDING LIME AND PRODUCTS
6. BURNT CLAY PRODUCTS
7. CEMENT AND CONCRETE (including concrete
reinforcement)
8. COMPOSITE MATRIX PRODUCTS (including
cement matrix products)
9. CONDUCTORS AND CABLES
10. DOORS, WINDOWS AND VENTILATORS
11. ELECTRICAL WIRING, FITTINGS AND
ACCESSORIES
12. FILLERS, STOPPERS AND PUTTIES
13. FLOOR COVERING, ROOFING AND OTHER
FINISHES
14. GLASS
15. GYPSUM BASED MATERIALS
16. LIGNOCELLULOSIC BUILDING MATERIALS
(including timber, bamboo and products thereof)
17. PAINTS AND ALLIED PRODUCTS
18. POLYMERS, PLASTICS AND
GEOSYNTHETICS/GEOTEXTILES
19. SANITARY APPLIANCES AND WATER
FITTINGS
20. SOIL-BASED PRODUCTS
21. STEEL AND ITS ALLOYS
22. STONES
23. STRUCTURAL SECTIONS
24. THERMAL INSULATION MATERIALS
25. THREADED FASTENERS AND RIVETS
26. UNIT WEIGHTS OF BUILDING MATERIALS
27. WATERPROOFING AND DAMP-PROOFING
MATERIALS
28. WELDING ELECTRODES AND WIRES
29. WIRE ROPES AND WIRE PRODUCTS
1. ALUMINIUM AND OTHER LIGHT METALS
AND THEIR ALLOYS
IS No. Title
733 : 1983 Specification for wrought
aluminium and aluminium alloys,
bars, rods and sections for general
engineering purposes (third
revision)
737 : 1986 Specification for wrought
aluminium and aluminium alloys,
sheet rods and strip for general
engineering purposes (third
revision)
738 : 1994 Specification for wrought
aluminium and aluminium alloy
drawn tube for general engineering
purposes (third revision)
740 : 1977 Specification for wrought
aluminium and aluminium alloy
rivet stock for general engineering
purposes (second revision)
1254 : 1991 Specification for corrugated
aluminium sheet (third revision)
1284 : 1975 Wrought aluminium alloy bolt and
screw stock for general engineering
purposes (second revision)
1285 : 2002 Specification for wrought
aluminium and aluminium alloys,
extruded round tube and hollow
sections for general engineering
purposes (third revision)
2479 : 1981 Colour code for the identification
of aluminium and aluminium
alloys for general engineering
purposes (second revision)
2676 : 1981 Dimensions for wrought
aluminium and aluminium alloy
sheet and strip
2677 : 1979 Dimensions for wrought
aluminium and aluminium alloys,
plates and hot rolled sheets
14712 : 1999 Wrought aluminium and its alloys
— Chequered/tread sheets for
general engineering purposes —
Specification
2. BITUMEN AND TAR PRODUCTS
73 : 1992 Specification for paving bitumen
(second revision)
NATIONAL BUILDING CODE OF INDIA
IS No.
212 : 1983
215 : 1995
216 : 1961
217 : 1988
218 : 1983
454 : 1994
702 : 1988
1201 to 1220
1201 : 1978
1202 : 1978
1203 : 1978
1204: 1978
1205 : 1978
1206
(Part 1) : 1978
(Part 2) : 1978
(Part 3) : 1978
1207 : 1978
1208 : 1978
1209 : 1978
1210: 1978
1211 : 1978
1212 : 1978
1213 : 1978
1215 : 1978
1216 : 1978
1217 : 1978
Title
Specification for crude coal tar for
general use (second revision)
Specification for road tar (third
revision)
Specification for coal tar pitch (first
revision)
Specification for cutback bitumen
(second revision)
Specification for creosote oil for
use as wood preservatives (second
revision)
Specification for cutback bitumen
from waxy crude (second revision)
Specification for industrial bitumen
(second revision)
Methods for testing tar and
bituminous materials
Sampling (first revision)
Determination of specific gravity
(first revision)
Determination of penetration (first
revision)
Determination of residue of
specified penetration (first revision)
Determination of softening point
(first revision)
Determination of viscosity:
Industrial viscosity (first revision)
Absolute viscosity (first revision)
Kinematic viscosity (first revision)
Determination of equiviscous
temperature (EVT) (first revision)
Determination of ductility (first
revision)
Determination of flash point and
fire point (first revision)
Float test (first revision)
Determination of water content
(Dean and Stark method) (first
revision)
Determination of loss of heating
(first revision)
Distillation test (first revision)
Determination of matter insoluble
in toluene (first revision)
Determination of solubility
in carbon disulphide or
trichloroethylene (first revision)
Determination of mineral matter
(ASH) (first revision)
IS No.
1218:
: 1978
1219:
: 1978
1220:
: 1978
3117
:2004
8887
:2004
9381 :
1979
9382 : 1979
10511 : 1983
10512 : 2003
13758
(Part 1) : 1993
(Part 2) : 1993
15172 : 2002
15173 : 2002
15174 : 2002
15462 : 2004
Title
Determination of phenols (first
revision)
Determination of naphthalene (first
revision)
Determination of volatile matter
content (first revision)
Specification for bitumen emulsion
for roads (anionic type) (first
revision)
Specification for bitumen emulsion
for roads (cationic type) (second
revision)
Methods for testing tar and
bituminous materials: Determination
of FRAASS breaking point of
bitumen
Methods for testing tar and
bituminous materials: Determination
of effect of heat and air by thin film
oven test
Method for determination of
asphaltenes in bitumen by
precipitation with normal haptane
Method for determination of wax
content in bitumen (first revision)
Coal tar pitch:
Determination of matter insoluble
in quinoline
Determination of coking value
Methods for testing tar and
bituminous materials —
Determination of curing index for
cutback bitumens
Methods for testing tars and
bituminous materials —
Determination of breaking point
for cationic bitumen emulsion
Methods for testing tar and
bituminous material —
Determination of breaking point
for anionic bitumen emulsion
Specification for polymer and
rubber modified bitumen
3. BUILDER'S HARDWARE
204 Specification for tower bolts:
(Part 1) : 1991 Ferrous metals (fifth revision)
(Part 2) : 1992 Non-ferrous metals (fifth revision)
205 : 1992 Specification for non-ferrous metal
butt hinges (fourth revision)
PART 5 BUILDING MATERIALS
IS No. Title
206 : 1992 Specification for tee and strap
hinges {fourth revision)
208 : 1996 Specification for door handles {fifth
revision)
281 : 1991 Specification for mild steel sliding
door bolts for use with padlock
{third revision)
362 : 1 99 1 Specification for parliament hinges
(fifth revision)
363 : 1993 Specification for hasps and staples
(fourth revision)
364 : 1993 Specification for fanlight catch
(third revision)
452 : 1973 Specification for door springs, rat-
tail type (second revision)
453 : 1993 Specification for double-acting
spring fringes (third revision)
729 : 1979 Specification for drawer locks,
cupboard locks and box locks
(third revision)
1019 : 1974 Specification for rim latches
(second revision)
1341 : 1992 Specification for steel butt hinges
(sixth revision)
1823 : 1980 Specification for floor door
stoppers (third revision)
1837 : 1966 Specification for fanlight pivots
(first revision)
2209 : 1976 Specification for mortice locks
(vertical type) (third revision)
2681 : 1993 Specification for non-ferrous metal
sliding door bolts for use with
padlocks (third revision)
3564 : 1995 Specification for door closers
(hydraulically regulated) (second
revision)
3818 : 1992 Specification for continuous
(piano) hinges (third revision)
3828 : 1966 Specification for ventilator chains
3843 : 1995 Specification for steel backflap
hinges (first revision)
3847 : 1992 Specification for mortice night
latches (first revision)
4621 : 1975 Specification for indicating bolts
for use in public baths and
lavatories (first revision)
4948 : 2002 Specification for welded steel wire
fabric for general use (second
revision)
IS No. Title
4992 : 1975 Specification for door handles for
mortice locks (vertical type) (first
revision)
5187 : 1972 Specification for flush bolts (first
revision)
5899 : 1970 Specification for bathroom latches
5930 : 1970 Specification for mortice latch
(vertical type)
6315 : 1992 Specification for floor springs
(hydraulically regulated) for heavy
doors (second revision)
6318 : 1971 Specification for plastic window
stays and fasteners
6343 : 1982 Specification for door closers
(pneumatically regulated) for light
door weighing up to 40 kg (first
revision)
6607 : 1972 Specification for rebated mortice
locks (vertical type)
7196 : 1974 Specification for hold fast
7197 : 1974 Specification for double action
floor springs (without oil check) for
heavy doors
7534 : 1985 Specification for sliding locking
bolts for use with padlocks (first
revision)
7540 : 1974 Specification for mortice dead
locks
8756 : 1978 Specification for ball catches for
use in wooden almirah
8760 : 1978 Specification for mortice sliding
door locks, with lever mechanism
9106 : 1979 Specification for rising butt hinges
9131 : 1979 Specification for rim locks
9460 : 1980 Specification for flush drop handle
for drawer
9899 : 1981 Specification for hat coat and
wardrobe hooks
10019 : 1981 Specification for mild steel stays
and fasteners
10090 : 1982 Specification for numericals
1 0342 : 1 982 Specification for curtain rail system
12817 : 1997 Specification for stainless steel butt
hinges (first revision)
12867 : 1989 Specification for PVC hand rails
covers
14912 : 2001 Specification for door closers
concealed type (hydraulically
regulated)
NATIONAL BUILDING CODE OF INDIA
IS No. Title
4. BUILDING CHEMICALS
a) Anti-termite Chemicals
632 : 1978 Specification for gamma-BHC
(lindane) emulsifiable concentrates
(fourth revision)
8944 : 1978 Specification for chlorpyrifos
emulsifiable concentrates
b) Chemical Admixture/Water Proofing Compounds
2645 : 2003 Specification for integral
waterproofing compounds for
cement mortar and concrete
(second revision)
6925 : 1973 Methods of test for determination
of water soluble chlorides in
concrete admixtures
9103 : 1999 Specification for concrete
admixtures (first revision)
c) Sealants/Fillers
1834: 1984
1838
(Part 1): 1983
(Part 2) : 1984
11433
(Part 1) : 1985
12118
(Part 1) : 1987
(Part 2) : 1987
d) Adhesives
848: 1974
849 : 1994
851 : 1978
852: 1994
Specification for hot applied
sealing compound for joint in
concrete (first revision)
Specification for preformed fillers
for expansion joint in concrete
pavements and structures (non-
extruding and resilient type):
Bitumen impregnated fibre (first
revision)
CNSL aldehyde resin and coconut
pith
Specification for one grade
polysulphide based joint sealant:
Part 1 General requirements
Specification for two parts
polysulphide based sealants:
General requirements
Methods of test
Specification for synthetic resin
adhesives for plywood (phenolic
and aminoplastic) (first revision)
Specification for cold setting case
in glue for wood (first revision)
Specification for synthetic resin
adhesives for construction work
(non-structural) in wood (first
revision)
Specification for animal glue for
general wood-working purposes
(second revision)
IS No. Title
1508 : 1972 Specification for extenders for use
in synthetic resin adhesives (urea-
formaldehyde) for plywood (first
revision)
4835 : 1979 Specification for polyvinyl acetate
dispersion-based adhesives for
wood (first revision)
9188 : 1979 Performance requirements for
adhesive for structural laminated
wood products for use under
exterior exposure condition
12830 : 1989 Rubber based adhesives for fixing
PVC tiles to cement
12994 : 1990 Epoxy adhesives, room temperature
curing general purpose
5. BUILDING LIME AND PRODUCTS
712 : 1984 Specification for building limes
(third revision)
1 624 : 1 986 Method of field testing of building
lime (first revision)
2686 : 1977 Specification for cinder as fine
aggregates for use in lime concrete
(first revision)
3068 : 1986 Specification for broken brick
(burnt-clay) coarse aggregates for
use in lime concrete (second
revision)
3115 : 1992 Specification for lime based blocks
(second revision)
3182 : 1986 Specification for broken bricks
(burnt clay) fine aggregates for use
in lime mortar (second revision)
4098 : 1983 Specification for lime-pozzolana
mixture (first revision)
4139 : 1989 Specification for calcium silicate
bricks (second revision)
6932 Method of tests for building limes:
(Part 1) : 1973 Determination of insoluble residue,
loss on ignition, insoluble matter,
silicon dioxide, ferric and
aluminium oxide, calcium oxide
and magnesium oxide
(Part 2) : 1973 Determination of carbon dioxide
content
(Part 3) : 1973 Determination of residue on
slaking of quicklime
(Part 4) : 1973 Determination of fineness of
hydrated lime
(Part 5) : 1973 Determination of unhydrated
oxide
PART 5 BUILDING MATERIALS
IS No.
(Part 6) : 1973
(Part 7) : 1973
(Part 8) : 1973
(Part 9) : 1973
(Part 10) : 1973
(Part 11): 1984
10360 : 1982
10772 : 1983
12894:2002
Title
Determination of volume yield of
quicklime
Determination of compressive and
transverse strength
Determination of workability
Determination of soundness
Determination of popping and
pitting of hydrated lime
Determination of setting time of
hydrated lime
Specification for lime pozzolana
concrete blocks for paving
Specification for quick setting lime
pozzolana mixture
Specification for pulverized fuel
ash lime bricks (first revision)
6. BURNT CLAY PRODUCTS
a) Blocks
3952 : 1988
Specification for burnt hollow
bricks for walls and partitions
(second revision)
b) Soil-Based Products
1725 : 1982 Specification for soil-based blocks
used in general building construction
c) Bricks
1077 : 1992 Specification for common burnt
clay building bricks (fifth revision)
2117 : 1991 Guide for manufacture of hand-
made-common burnt clay building
bricks (third revision)
2180 : 1988 Specification for heavy duty burnt
clay building bricks (third revision)
2222 : 1991 Specification for burnt clay
perforated building bricks (fourth
revision)
2691 : 1988 Specification for burnt clay facing
bricks (second revision)
3495 (Parts Methods of test of burnt clay
1 to 4) : 1992 building bricks (third revision)
3583 : 1988 Specification for burnt clay paving
bricks (second revision)
4885 : 1988 Specification for sewer bricks (first
revision)
5454 : 1978 Methods for sampling of clay
building bricks
5779 : 1986 Specification for burnt clay soling
bricks (first revision)
IS No.
6165 : 1992
11650: 1991
13757 : 1993
d) Jallies
7556 : 1988
e) Tiles
654 : 1992
1464 : 1992
1478 : 1992
2690
(Part 1) : 1993
(Part 2) : 1992
3367 : 1993
3951
(Part 1) : 1975
(Part 2) : 1975
13317 : 1992
Title
Dimensions for special shapes of
clay bricks (first revision)
Guide for manufacture of common
burnt clay building bricks by semi-
mechanized process (first revision)
Specification for burnt clay fly ash
building bricks
Specification for burnt clay jallies
(first revision)
Specification for clay roofing tiles,
Mangalore pattern (third revision)
Specification for clay ridge and
ceiling tiles (second revision)
Specification for clay flooring tiles
(second revision)
Specification for burnt clay flat
terracing tiles:
Machine made (second revision)
Handmade (second revision)
Specification for burnt clay tiles for
use in lining irrigation and drainage
works (second revision)
Specification for hollow clay tiles
for floor and roofs:
Filler type (first revision)
Structural type (first revision)
Specification for clay roofing
camty tiles, half round and flat tiles
7. CEMENT AND CONCRETE (including concrete
reinforcement)
a) Aggregates
383 : 1970 Specification for coarse and fine
aggregates from natural sources for
concrete (second revision)
1542 : 1992 Specification for sand for plaster
(second revision)
2116: 1980 Specification for sand for masonry
mortars (first revision)
2386 Methods of test for aggregates for
concrete:
(Part 1) : 1963 Particle size and shape
(Part 2) : 1963 Estimation of deleterious materials
and organic impurities
(Part 3) : 1963 Specific gravity, density, voids,
absorption and bulking
10
NATIONAL BUILDING CODE OF INDIA
IS No.
(Part 4) : 1963
(Part 5) : 1963
(Part 6) : 1963
(Part 7) : 1963
(Part 8) : 1963
2430 : 1986
6579 : 1981
9142: 1979
b) Cement
269 : 1989
455 : 1989
1489
(Part 1): 1991
(Part 2) : 1991
3466 : 1988
6452 : 1989
6909 : 1990
8041 : 1990
8042 : 1989
8043 : 1991
8112: 1989
12269: 1987
12330: 1988
12600: 1989
Title
Mechanical properties
Soundness
Measuring mortar making properties
of fine aggregates
Alkali aggregate reactivity
Petrographic examination
Methods of sampling of aggregates
of concrete (first revision)
Specification for coarse aggregate
for water bound macadam (first
revision)
Specification for artificial light-
weight aggregates for concrete
masonry units
Specification for ordinary portland
cement, 33 Grade (fourth revision)
Specification for Portland slag
cement (fourth revision)
Specification for Portland
pozzolana cement:
Flyash based (third revision)
Calcined clay based (third revision)
Specification for masonry cement
(second revision)
Specification for high alumina
cement for structural use (first
revision)
Specification for supers ulphated
cement
Specification for rapid hardening
Portland cement (second revision)
Specification for white Portland
cement (second revision)
Specification for hydrophobic
Portland cement (second revision)
Specification for 43 grade ordinary
Portland cement (first revision)
Specification for 53 grade ordinary
Portland cement
Specification for sulphate resisting
Portland cement
Specification for low heat Portland
cement
c) Mineral/Chemical Admixtures and Pozzolanas
1344 : 1981 Specification for calcined clay
pozzolana (second revision)
1121 : 1967 Methods of test for pozzolanic
materials (first revision)
IS No. Title
3812 Specification for pulverized fuel
ash:
(Part 1) : 2003 For use as pozzolana in cement,
cement mortar and concrete
(second revision)
(Part 2) : 2003 For use as admixture in cement
mortar and concrete (second
revision)
6491 : 1972 Method of sampling of flyash
6925 : 1973 Methods of test for determination
of water soluble chlorides in
concrete admixtures
9103 : 1999 Specification for admixtures for
concrete (first revision)
12089 : 1987 Specification for granulated slag
for manufacture of Portland slag
cement
12870 : 1989 Methods of sampling calcined clay
pozzolana
15388 : 2003 Specification for silica fume
d) Concrete
456 : 2000 Code of practice for plain and
reinforced concrete (fourth
revision)
1343 : 1980 Code of practice for prestressed
concrete (first revision)
4926 : 2003 Code of practice for ready-mixed
concrete (third revision)
e) Cement and Concrete Sampling and Methods of
Test
516 : 1959 Methods of test for strength of
concrete
1 199 : 1959 Methods of sampling and analysis
of concrete
2770 Methods of testing bond in
(Part 1) : 1967 reinforced concrete: Part 1 Pullout
test
3085 : 1965 Methods of test for permeability of
cement mortar and concrete
3535 : 1986 Methods of sampling hydraulic
cement (first revision)
4031 Methods of physical tests for
hydraulic cement:
(Part 1) : 1996 Determination of fineness by dry
sieving (second revision)
(Part 2) : 1999 Determination of fineness by
specific surface by Blaine air
permeability method (second
revision)
PART 5 BUILDING MATERIALS
11
IS No.
(Part 3) : 1988
(Part 4) : 1988
(Part 5) : 1988
(Part 6): 1988
(Part 7): 1988
(Part 8) : 1988
(Part 9) : 1988
(Part 10) : 1988
(Part 11): 1988
(Part 12): 1988
(Part 13) : 1988
(Part 14) : 1989
(Part 15): 1991
4032: 1985
5816: 1999
8142: 1976
9013 : 1978
9284 : 1979
12423 : 1988
12803 : 1989
Title
Determination of soundness (first
revision)
Determination of consistency of
standard cement paste (first
revision)
Determination of initial and final
setting times (first revision)
Determination of compressive
strength of hydraulic cement (other
than masonry cement) (first
revision)
Determination of compressive
strength of masonry cement (first
revision)
Determination of transverse and
compressive strength of plastic
mortar using prism (first revision)
Determination of heat of hydration
(first revision)
Determination of drying shrinkage
(first revision)
Determination of density (first
revision)
Determination of air content of
hydraulic cement mortar (first
revision)
Measurement of water retentivity
of masonry cement (first revision)
Determination of false set
Determination of fineness by wet
sieving
Methods of chemical analysis for
hydraulic cement (first revision)
Method of test for splitting
tensile strength of concrete (first
revision)
Methods of test for determining
setting time of concrete by
penetration resistance
Method of making, curing and
determining compressive strength
of accelerated cured concrete test
specimens
Method of test for abrasion
resistance of concrete
Methods for colorometric analysis
of hydraulic cement
Methods of analysis of hydraulic
cement by X-ray fluorescence
spectrometer
IS No. Title
12813 : 1989 Method of analysis of hydraulic
cement by atomic absorption
spectrophotometer
13311 Methods of non-destructive testing
of concrete:
Ultrasonic pulse velocity
Rebound hammer
(Part 1) : 1992
(Part 2) : 1992
f) Treatment of Concrete Joints
1834 : 1984
1838
(Part 1) :
(Part 2)
1983
1984
10566 : 1983
11433
(Part 1) : 1985
(Part 2) : 1986
12118
(Part 1) : 1987
(Part 2) : 1987
g) Concrete Reinforcement
Specification for hot applied
sealing compound for joint in
concrete (first revision)
Specification for preformed fillers
for expansion joint in concrete
pavements and structures (non-
extruding and resilient type):
Bitumen impregnated fibre (first
revision)
CNSL aldehyde resin and coconut
pith
Methods of test for preformed
fillers for expansion joints in
concrete paving and structural
construction
Specification for one grade
polysulphide based joint sealant:
General requirements
Methods of test
Specification for two parts
polysulphide based sealants:
General requirements
Methods of test
432 Specification for mild steel and
medium tensile steel bars and hard
drawn steel wire for concrete
reinforcement:
(Part 1) : 1982 Mild steel and medium tensile steel
bars (third revision)
(Part 2) : 1982 Hard drawn steel wire (third
revision)
1566 : 1982 Specification for hard drawn steel
wire fabric for concrete
reinforcement (second revision)
1608 : 1995 Mechanical testing of materials —
Tensile testing
1785 Specification for plain hard
drawn steel wire for prestressed
concrete:
12
NATIONAL BUILDING CODE OF INDIA
IS No. Title
(Part 1) : 1983 Cold drawn stress-relieved wire
(second revision)
(Part 2) : 1983 As drawn wire (first revision)
1786 : 1985 Specification for high strength
deformed steel bars and wires for
concrete reinforcement (third
revision)
2090 : 1983 Specification for high tensile steel
bars used in prestressed concrete
(first revision)
6003 : 1983 Specification for indented wire
for prestressed concrete (first
revision)
6006 : 1983 Specification for uncoated stress-
relieved strand for prestressed
concrete (first revision)
10790 Methods of sampling of steel
for prestressed and reinforced
concrete:
(Part 1) : 1984 Prestressing steel
(Part 2) : 1984 Reinforcing steel
13620 : 1993 Specification for fusion bonded
epoxy coated reinforcing bars
14268 : 1995 Specification for uncoated stress
relieved low relaxation seven ply
strand for prestressed concrete
8. COMPOSITE MATRIX PRODUCTS
a) Cement Matrix Products
i) Precast Concrete Products
21 85 Specification for concrete masonry
units:
(Part 1) : 1979 Hollow and solid concrete blocks
(second revision)
(Part 2) : 1983 Hollow and solid lightweight
concrete blocks (first revision)
(Part 3) : 1984 Autoclaved cellular (aerated)
concrete blocks (first revision)
4996 : 1984 Specification for reinforced
concrete fence posts (first revision)
5751 : 1984 Specification for precast concrete
coping blocks (first revision)
5758 : 1984 Specification for precast concrete
kerbs (first revision)
5820 : 1970 Specification for precast concrete
cable covers
6072 : 1971 Specification for autoclaved
reinforced cellular concrete wall
slabs
IS No.
6073 : 1971
6441
(Part 1) : 1972
(Part 2) : 1972
(Part 4)': 1972
(Part 5) : 1972
(Part 6) : 1973
(Part 7) : 1973
(Part 8) : 1973
(Part 9) : 1973
6523 : 1983
9872 : 1981
9893 : 1981
12440 : 1988
12592 : 2002
13356: 1992
13990 : 1994
14143 : 1994
14201 : 1994
14241 : !994
Title
Specification for autoclaved
reinforced cellular concrete floor
and roof slabs
Methods of test for autoclaved
cellular concrete products:
Determination of unit weight or
bulk density and moisture content
Determination of drying shrinkage
Corrosion protection of steel
reinforcement in autoclaved
cellular concrete
Determination of compressive
strength
Strength, deformation and cracking
of flexural members subject to
bending-short duration loading test
Strength, deformation and cracking
of flexural members subject to
bending-sustained loading test
Loading tests for flexural members
in diagonal tension
Jointing of autoclaved cellular
concrete elements
Specification for precast reinforced
concrete door and window frames
(first revision)
Specification for precast concrete
septic tanks
Specification for precast concrete
blocks for lintels and sills
Specification for precast concrete
stone masonry blocks
Specification for precast concrete
manhole covers and frames (first
revision)
Specification for precast
ferrocement water tanks (250 to
10 000 litres capacity)
Specification for precast reinforced
concrete planks and joists for
flooring and roofing
Specification for prefabricated
brick panel and partially precast
concrete joist for flooring and
roofing
Specification for precast reinforced
concrete channel unit for
construction of floors and roofs
Specification for precast L-Panel
units for roofing
PART 5 BUILDING MATERIALS
13
IS No. Title
ii) Asbestos Fibre Cement Products
459 : 1992 Specification for corrugated and
semi-corrugated asbestos cement
sheets (third revision)
1592 : 2003 Specification for asbestos cement
pressure pipes and joints (fourth
revision)
1626 Specification for asbestos cement
building pipes and pipe fittings,
gutters and gutter fittings and
roofing fittings:
(Part 1) : 1994 Pipes and pipe fittings (second
revision)
(Part 2) : 1994 Gutters and gutter fittings (second
revision)
(Part 3) : 1994 Roofing fittings (second revision)
2096 : 1992 Specification for asbestos cement
flat sheets (first revision)
2098 : 1997 Specification for asbestos cement
building boards (first revision)
5913: 2003 Methods of test for asbestos cement
products (second revision)
6908 : 1991 Specification for asbestos cement
pipes and fittings for sewerage and
drainage (first revision)
7639 : 1975 Method of sampling asbestos
cement products
9627 : 1980 Specification for asbestos cement
pressure pipes (light duty)
13000 : 1990 Silica-asbestos-cement flat sheets
— Specification
13008 : 1990 Specification for shallow corrugated
asbestos cement sheets
iii) Other Fibre Cement Products
14862 : 2000 Specification for fibre cement flat
sheets
14871 : 2000 Specification for products in
fibre reinforced cement long
corrugated or asymmetrical section
sheets and fittings for roofing and
cladding
iv) Concrete Pipes and Pipes Lined/Coated with
Concrete or Mortar
458 : 2003 Specification^or precast concrete
pipes (with and without
reinforcement) (fourth revision)
784 : 2001 Specification for prestressed
concrete pipes (including specials)
(second revision)
IS No,
1916: 1989
3597 : 1998
4350 : 1967
7319: 1974
7322 : 1985
15155 : 2002
Title
Specification for steel cylinder pipe
with concrete lining and coating
(first revision)
Methods of test for concrete pipes
(second revision)
Specification for concrete porous
pipes for under drainage
Specification for perforated
concrete pipes
Specification for specials for steel
cylinder reinforced concrete pipes
(first revision)
Specification for bar/wire wrapped
steel cylinder pipe with mortar
lining and coating
b) Resin Matrix Products
1998 : 1962 Methods of test for thermosetting
synthetic resin bonded laminated
sheets
2036 : 1995 Specification for phenolic
laminated sheets (second revision)
2046 : 1995 Specification for decorative
thermosetting synthetic resin
bonded laminated sheets (second
revision)
9. CONDUCTORS AND CABLES
694 : 1990 Specification for PVC insulated
cables for working voltages up to
and including 1 100 V (third
revision)
1554 Specification for PVC insulated
(heavy duty) electric cables:
(Part 1) : 1988 For working voltages up to and
including 1 100 V (third revision)
(Part 2) : 1988 For working voltages from 3.3 kV
up tp and including 1 1 kV (second
revision)
4289 Specification for flexible cables for
lifts and other flexible:
(Part 1) : 1984 Elastomer insulated cables (first
revision)
(Part 2) : 2000 PVC insulated circular cables
7098 Specification for cross-linked
#Pv polyethylene insulated PVC
sheathed cables:
(Part 1) : 1988 For working voltage up to
and including 1 100 V (second
revision)
14
NATIONAL BUILDING CODE OF INDIA
IS No,
Title
IS No.
(Part 2) : 1985
(Part 3) : 1993
For working voltages from 3.3 kV
up to and including 33 kV (first
revision)
For working voltages from 66 kV
up to and including 220 kV (first
revision)
(Part 24) :
(Part 25) :
(Part 26) :
1984
1984
1984
9968
Specification for elastomer-
insulated cables:
(Part 27) :
1984
(Part 1) : 1988
(Part 2) : 2002
10810
For working voltages up to and
including 1 100 V (first revision)
For working voltages from 3.3 kV
up to and including 33 kV (first
revision)
Methods of test for cables
(Part 28) :
(Part 29) :
(Part 30):
(Part 31):
(Part 32) :
(Part 33) :
(Part 34) :
(Part 35) :
1984
1984
1984
1984
1984
1984
1984
(PartO): 1984
General
(Part 1) : 1984
(Part 2) : 1984
Annealing test for wires used in
conductors
Tensile test for aluminium wires
1984
(Part 3) : 1984
Wrapping test for aluminium
(Part 36) :
1984
(Part 4) : 1984
wires
Persulphate test of conductor
(Part 37) :
1984
(Part 5): 1984
Conductor resistance test
(Part 38):
1984
(Part 6) : 1984
Thickness of thermoplastic and
elastomeric insulation and sheath
(Part 39) :
1984
(Part 7) : 1984
Tensile strength and elongation
at break of thermoplastic and
elastomeric insulation and sheath
(Part 40) :
1984
(Part 8) : 1984
(Part 9) : 1984
Breaking strength and elongation
at break for impregnated paper
insulation
Tear resistance for paper insulation
(Part 41) :
(Part 42) :
: 1984
: 1984
(Part 10) : 1984
(Part 11): 1984
(Part 12) : 1984
(Part 13) : 1984
(Part 14): 1984
(Part 15): 1984
Loss of mass test
Thermal ageing in air
Shrinkage test
Ozone resistance test
Heat shock test
Hot deformation test
(Part 43) :
(Part 44)
(Part 45)
(Part 46)
(Part 47)
: 1984
:1984
: 1984
:1984
:1984
(Part 16) : 1986
. Accelerated ageing test by oxygen
pressure method
(Part 48)
(Part 49)
: 1984
:1984
(Part 17): 1986
(Part 18) : 1984
Tear resistance test for heavy duty
sheath
Colour fastness to day light
(Part 50)
(Part 51)
(Part 52)
: 1984
: 1984
:1984
(Part 19) : 1984
Bleeding and blooming test
(Part 53)
:1984
(Part 20) : 1984
Cold bend test
(Part 54)
:1984
(Part 21): 1984
(Part 22) : 1984
Cold impact test
Vicat softening point
(Part 55)
(Part 56)
:1986
: 1987
(Part 23) : 1984 Melt-flow index
Title
Water soluble impurities test of
insulating paper
Conductivity of water extract test
of insulating paper
pH value of water extract test of
insulating paper
Ash content test of insulating
paper
Water absorption test (Electrical)
Environmental stress cracking test
Hot set test
Oil resistance test
Carbon content test for polyethylene
Water absorption test (Gravimetric)
Measurement of thickness of
metallic sheath
Determination of tin in lead alloy
for sheathing
Dimensions of armouring material
Tensile strength and elongation at
break of armouring materials
Torsion test on galvanized steel
wires for armouring
Winding test on galvanized steel
strips for armouring
Uniformity of zinc coating on steel
armour
Mass of zinc coating on steel
armour
Resistivity test of armour wires and
strips and conductance test of
armour (wires/strips)
Insulation resistance
Spark test
High voltage test
Partial discharge test
Impulse test
Dielectric power factor test
Heating cycle test
Bending test
Dripping test
^Drainage test
Rammability test
Static flexibility test
Abrasion test
Accelerated ageing by the air-
pressure method
PART 5 BUILDING MATERIALS
15
IS No.
(Part 57) : 1987
(Part 58) : 1998
(Part 59) : 1988
(Part 60) : 1988
(Part 61) : 1988
(Part 62) : 1993
(Part 63) : 1993
(Part 64) : 2003
12943 : 1990
Title
Flexing test
Oxygen index test
Determination of the amount of
halogen acid gas evolved during
combustion of polymeric materials
taken from cables
Thermal stability of PVC insulation
and sheath
Flame retardant test
Fire resistance test for bunched
cables
Smoke density of electric cables
under fire conditions
Measurement of temperature index
Brass glands for PVC cables
10. DOORS, WINDOWS AND VENTILATORS
a) Wooden Doors, Windows and Ventilators
1003 Specification for timber panelled
and glazed shutters:
(Part 1) : 2003 Door shutters (fourth revision)
(Part 2) : 1994 Window and ventilator shutters
(third revision)
1826 : 1961 Specification for Venetian blinds
for windows
2191 Specification for wooden flush
door shutters (cellular and hollow
core type):
(Parti): 1983 Plywood face panels (fourth
revision)
(Part 2) : 1983 Particle board face panels and
hardboard face panels (third
revision)
2202 Specification for wooden flush
door shutters (solid core type):
1 99 1 Plywood face panels (fifth revision)
1983 Particle board face panels and
hardboard face panels (third
revision)
4020 Method of tests for door shutters:
(Part 1) : 1998 General (third revision)
(Part 2) : 1998 Measurement of dimensions and
squareness (third revision)
(Part 3) : 1998 Measurement of general flatness
(third revision)
(Part 4) : 1998 Local planeness test (third revision)
(Part 5) : 1998 Impact indentation test (third
revision)
(Part 1)
(Part 2)
IS No.
(Part 6) : 1998
(Part 7) : 1998
(Part 8) : 1998
(Part 9) : 1998
(Part 10) : 1998
(Part 11): 1998
(Part 12) : 1998
(Part 13): 1998
(Part 14) : 1998
(Part 15) : 1998
(Part 16) : 1998
4021 : 1995
4962: 1968
6198 : 1992
b) Metal Doors,
1038 : 1983
1361 : 1978
1948: 1961
1949 : 1961
4351:2003
6248 : 1979
7452 : 1990
10451 : 1983
10521 : 1983
c) Plastic Doors and Windows
14856:2000
Title
Flexure test (third revision)
Edge loading test (third revision)
Shock resistance test (third revision)
Buckling resistance test (third
revision)
Slamming test (third revision)
Misuse test (third revision)
Varying humidity test (third
revision)
End immersion test (third revision)
Knife test (third revision)
Glue adhesion test (third revision)
Screw withdrawal resistance test
(third revision)
Specification for timber door,
window and ventilator frames
Specification for wooden side
sliding doors
Specification for ledged, braced
and battened timber shutters
(second revision)
Windows Frames and Ventilators
Specification for steel doors,
windows and ventilators (third
revision)
Specification for steel windows
for industrial buildings (first
revision)
Specification for aluminium doors,
windows and ventilators
Specification for aluminium
windows for industrial buildings
Specification for steel door frames
(second revision)
Specification for metal rolling
shutters and rolling grills (first
revision)^
Specification for hot rolled steel
sections for doors, windows and
ventilators (second revision)
Specification for steel sliding
shutters (top hung type)
Specification for collapsible gates
Specification for glass fibre
reinforced (GRP) panel type door
shutters for internal use
16
NATIONAL BUILDING CODE OF INDIA
IS No. Title
15380 : 2003 Specification for moulded raised
high density fibre (HDF) panel
doors
11. ELECTRICAL WIRING FITTINGS AND
ACCESSORIES
371 : 1999 Specification for ceiling roses
(third revision)
374 : 1979 Specification for electric ceiling
type fans and regulators {third
revision)
418 : 1978 Specification for tungsten filament
general service electric lamps
(third revision)
1258 : 1987 Specification for bayonet lamp
holders (third revision)
1293 : 1988 Specification for plugs and socket-
outlets rated voltage up to and
including 250 V and rated current
up to and including 16 amperes
(second revision)
1534 Specification for ballasts for
(Part 1): 1977 fluorescent lamps: Part I For
switch start circuits (second
revision)
1 554 PVC insulated (heavy duty) electric
cables:
(Part 1) : 1988 For working voltages upto and
including 1 100 V (third revision)
(Part 2) : 1988 For working voltages from 3.3 kV
upto and including 1 1 kV (second
revision)
1777 : 1978 Specification for industrial
luminaire with metal reflectors
(first revision)
2086 : 1 993 Specification for carriers and bases
used in re-wirable type electric
fuses up to 650 V (third revision)
2148 : 2004 Specification for flameproof
enclosures "d" for electrical
apparatus for explosive gas
atmospheres (third revision)
2206 Specification for flameproof
electric lighting fittings:
(Part 1): 1984 Well glass and bulkhead types (first
revision)
(Part 2) : 1976 Fittings using glass tubes
(Part 3) : 1989 Fittings using fluorescent lamps
and plastic covers
(Part 4) : 1987 Portable flame-proof handlamps
and approved flexible cables
IS No. Title
2215 : 1983 Specification for starters for
fluorescent lamps (third revision)
2412 : 1975 Specification for link clips for
electrical wiring (first revision)
2418 Specification for tubular
fluorescent lamps for general
lighting services:
(Parti): 1977 Requirements and tests (first
revision)
(Part 2) : 1977 Standard lamp data sheets (first
revision)
(Part 3) : 1977 Dimensions of G-5 and G-13 bi-
pin caps (first revision)
(Part 4) : 1977 Go and no-go gauges for G-5 and
G-13 bi-pin caps (first revision)
2667 : 1988 Specification for fittings for rigid
steel conduits for electrical wiring
(second revision)
2675 : 1983 Specification for enclosed
distribution fuseboards and cutouts
for voltages not exceeding 1 000 V
(second revision)
3287 : 1965 Specification for industrial lighting
fittings with plastic reflectors
3323 : 1980 Specification for bi-pin lamp
holders for tubular fluorescent
lamps (first revision)
3324 : 1982 Specification for holders for
starters for tubular fluorescent
lamps (first revision)
3419 : 1989 Specification for fittings for rigid
non-metallic conduits (second
revision)
3480 : 1966 Specification for flexible steel
conduits for electrical wiring
3528 : 1966 Specification for waterproof
electric lighting fittings
3553 : 1966 Specification for watertight electric
lighting fittings
3837 : 1976 Specification for accessories for
rigid steel conduits for electrical
wiring (first revision)
3854 : 1997 Specification for switches for
domestic and similar purposes
(second revision)
4012: 1967 Specification for dust-proof
electric lighting fittings
4013 : 1967 Specification for dust-tight electric
lighting fittings
PART 5 BUILDING MATERIALS
17
IS No.
Title
IS No.
Title
4160 : 1967
4615 : 1968
4649 : 1968
5077 : 1969
6538 : 1971
8030 : 1976
8828 : 1996
9537
(Part 1): 1980
(Part 2) : 1981
(Part 3) : 1983
(Part 4) : 1983
(Part 5) : 2000
(Part 6) : 2000
(Part 8) : 2003
9926: 1981
10322
(Part 1) : 1982
(Part 2) : 1982
(Part 3) : 1984
(Part 4) : 1984
(Part 5/Sec 1) :
1985
(Part 5/Sec 2) :
1985
(Part 5/Sec 3) :
1987
(Part 5/Sec 4) :
1987
Specification for interlocking
switch socket outlet
Specification for switch socket
outlets (non-interlocking type)
Specification for adaptors for
flexible steel conduits
Specification for decorative
lighting outfits
Specification for three-pin plugs
made of resilient material
Specification for luminaires for
hospitals
Specification for circuit-breakers
for over current protection for
household and similar installation
(second revision)
Specification for conduits for
electrical installations:
General requirements
Rigid steel conduits
Rigid plain conduits for insulating
materials
Pliable self-recovering conduits for
insulating materials
Pliable conduits of insulating
materials
Pliable conduits of metal or
composite materials
Rigid non-threadable conduits of
aluminium alloy
Specification for fuse wires used in
rewirable type electric fuses up to
650 V
Specification for luminaires:
General requirements
Constructional requirements
Screw and screwless terminations
Methods of tests
Particular requirements, Section 1
General purpose luminaires
Particular requirements, Section 2
Recessed luminaires
Particular requirements, Section 3
Luminaires for road and street
lighting
Particular requirements, Section 4
Portable general purpose
luminaires
(Part 5/Sec 5) :
1987
11037: 1984
13010 : 2002
13779 : 1999
13947
(Part 3) : 1993
14763 : 2000
14768
(Part 1) : 2000
(Part 2) : 2003
14772 : 2000
14927
(Part 1) : 2001
(Part 2) : 2001
14930
(Part 1) : 2001
(Part 2) : 2001
15368 : 2003
Particular requirements, Section 5
Flood light
Electronic type fan regulators
AC watt-hour meters, Class 0.5, 1
and 2 (first revision)
AC static watthour meters (Class 1
and 2) (first revision)
Specification for low-voltage
switchgear and controlgear: Part 3
Switches, disconnectors, switch
disconnectors and fuse
combination units
Conduit for electrical purposes,
outside diameters of conduits for
electrical installations and threads
for conduits and fittings
Conduit fittings for electrical
installations:
General requirements
Metal conduit fittings
Enclosures for accessories for
household and similar fixed
electrical installations
Cable trunking and ducting
systems for electrical installations
General requirements
Cable trunking and ducting
systems intended for mounting on
walls or ceilings
Conduit systems for electrical
installations:
General requirements
Particular requirements for conduit
system buried underground
Cable reels for household and
similar purposes
12. FILLERS, STOPPERS AND PUTTIES
110: 1983 Specification for ready mixed
paint, brushing, grey filler, for
enamels, for use over primers (first
revision)
419 : 1967 Specification for putty for use on
window frames (first revision)
423 : 1961 Specification for plastic wood, for
joiner's filler (revised)
3709 : 1 966 Specification for mastic cement for
bedding of metal windows
7164 : 1973 Specification for stopper
18
NATIONAL BUILDING CODE OF INDIA
IS No. Title
13184 : 1991 Specification for mastic filler,
epoxy based
13. FLOOR COVERING, ROOFING AND OTHER
FINISHES
a) Concrete Flooring
1237 : 1980 Specification for cement concrete
flooring tiles (first revision)
13801 : 1993 Specification for chequered cement
concrete tiles
b) Flooring Compositions
657 : 1982 Specification for materials for use
in the manufacture of magnesium
oxychloride flooring compositions
(second revision)
9162 : 1979 Methods of tests for epoxy resin,
hardeners and epoxy resin
composition for floor topping
9197 : 1979 Specification for epoxy resin,
hardness and epoxy resin
compositions for floor topping
10132: 1982 Method of test for materials
for use in the preparation of
magnesium oxychloride flooring
composition
c) Linoleum Flooring
653 : 1992 Specification for linoleum sheets
and tiles (third revision)
9704 : 1980 Methods of tests for linoleum
sheets and tiles
IS No. Title
heavy hydrocarbon products like
kerosene, diesel and furnace oil
d) Rubber Flooring
809 : 1992
Specification for rubber flooring
materials for general purposes
(second revision)
e) Bituminous Flooring
1195 : 2002 Specification for bitumen mastic
for flooring (third revision)
8374 ; 1977 Specification for bitumen mastic,
anti-static and electrically
conducting grade
9510 : 1980 Specification for bitumen mastic
acid resisting grade
13026 : 1991 Specification for bitumen mastic
for flooring for industries handling
LPG and other light hydrocarbon
products
15194 : 2002 Specification for pitch-mastic
flooring for industries handling
f) Plastic Flooring
3461 : 1980 .
3462 : 1986
3464 : 1986
Specification for PVC asbestos
floor tiles (first revision)
Specification for unbacked flexible
PVC flooring (second revision)
Methods of test for plastic flooring
and wall tiles (second revision)
g) Ceramic/Vitreous
2333 : 1992 Specification for plaster of Paris for
ceramic industry (second revision)
4457 : 1982 Specification for ceramic unglazed
vitreous acid resisting tile (first
revision)
13630 Method of test for ceramic tiles:
(Part 1) : 1993 Determination of dimensions and
surface quality
(Part 2) : 1992 Determination of water absorption
(Part 3) : 1992 Determination of moisture
expansion using boiling water —
Unglazed tiles
(Part 4) : 1992 Determination of linear thermal
expansion
(Part 5) : 1992 Determination of resistance to
thermal shock
(Part 6) : 1993 Determination of modulus of rupture
(Part 7) : 1993 Determination of chemical resistance
— Unglazed tiles
(Part 8) : 1993 Determination of chemical resistance
— Glazed tiles
(Part 9) : 1993 ^termination of crazing resistance
— Glazed tiles
(Part 10) : 1993 Determination of frost resistance
(Part 11) : 1993 Determination of resistance to
surface abrasion — Glazed tiles
(Part 12) : 1993 Deterrnjtnationofresistancetodeep
abrasion — Unglazed tiles
(Part 13) : 1993 Determination of scratch hardness
of surface according to Mohs'
13711 : 1993 Sampling and basis for acceptance
of ceramic tiles
13753 : 1993 Specification for dust pressed
ceramic tiles with water absorption
of E> 10% Group (Bill)
13754 : 1993 Specification for dust pressed
ceramic tiles with water absorption
of 6% < E < 10% Group (B II b)
PART 5 BUILDING MATERIALS
19
IS No.
13755 : 1993
Title
Specification for dust pressed
ceramic tiles with water absorption
of 3% < E < 6% Group (B II a)
13756: 1993 Specification for dust pressed
ceramic tiles with water absorption
of E < 3% Group B I
h) Other Floorings
4456
Methods of test for chemical
resistant mortars:
(Part 1) : 1967
(Part 1) : 1967
Silicate type and resin type
(Part 2) : 1967
(Part 2) : 1967
Sulphur type
4832
4457 : 1982
Specification for ceramic unglazed
vitreous acid resisting tile (first
(Part 1) : 1969
revision)
(Part 2) : 1969
4832
Specification for chemical resistant
(Part 3) : 1968
mortars:
15418:2003
(Part 1) : 1969
Silicate type
(Part 2) : 1969
Resin type
(Part 3) : 1968
Sulphur type
14. GLASS
4860 : 1968
Specification for acid resistant
bricks
2553
(Part 1) : 1990
j) Roofing
277 : 1992
Specification for galvanized steel
sheets (plain and corrugated (fifth
2835 : 1987
revision)
3438 : 1994
459 : 1992 Specification for corrugated and
semi-corrugated asbestos cement
sheets (third revision)
654 : 1992 Specification for clay roofing tiles,
Mangalore pattern (third revision)
1464 : 1992 Specification for clay ridge and
ceiling tiles (second revision)
2690 Specification for burnt clay flat
terracing tiles:
(Part 1) : 1993 Machine made (second revision)
(Part 2) : 1992 Hand-made (second revision)
395 1 Specification for hollow clay tiles
for floor and roofs:
(Part 1) : 1975 Filler type (first revision)
(Part 2) : 1975 Structural type (first revision)
10388 : 1982 Specification for corrugated coir
wood wool cement roofing sheets
12583 : 1988 Specification for corrugated
bitumen roofing sheets
12866 : 1989 Specification for plastic translucent
sheets made from thermosetting
polyester resin (glass fibre
reinforced)
IS No. Title
13317 : 1992 Specification for clay roofing
camty tiles, half round and flat
tiles
k) Wall Coverings/Finishing
1542 : 1992 Specification for sand for plaster
(second revision)
4456 Methods of test for chemical
resistant mortars:
Silicate type and resin type
Sulphur type
Specification for chemical resistant
mortars:
Silicate type
Resin type
Sulphur type
Specification for finished wall
papers, wall vinyls and plastic wall
coverings in roll form
Specification for safety glass:
Part 1 General purpose (third
revision)
Specification for flat transparent
sheet glass (third revision)
Specification for silvered glass
mirrors for general purposes
(second revision)
5437 : 1 994 Specification for figured rolled and
wired glass (first revision)
14900 : 2000 Specification for transparent float
glass
15. GYPSUM BASED MATERIALS
2095
(Part 1) : 1996
(Part 2) : 2001
(Part 3) : 1996
2542
(Part 1/Sec 1):
1978
(Part 1/Sec 2) :
1978
Specification for gypsum plaster
boards:
Plain gypsum plaster boards
Coated/laminated gypsum plaster
boards
Reinforced gypsum plaste^boards
(second revision)
Methods of test for gypsum plaster,
concrete and products:
Plaster and concrete, Section 1
Normal consistency of gypsum
plaster (first revision)
Plaster and concrete, Section 2
Normal consistency of gypsum
concrete (first revision)
20
NATIONAL BUILDING CODE OF INDIA
IS No.
(Part 1/Sec 3) ;
1978
(Part 1/Sec 4) :
1978
(Part 1/Sec 5):
1978
(Part 1/Sec 6) :
1978
(Part 1/Sec 7)
1978
(Part 1/Sec 8) :
1978
(Part 1/Sec 9) :
1978
(Part 1/Sec 10)
1978
(Part 1/Sec 11)
1978
(Part 1/Sec 12):
1978
(Part2/Sec 1):
1981
(Part 2/Sec 2) :
1981
(Part 2/Sec 3) :
1981
(Part 2/Sec 4) :
1981
(Part 2/Sec 5) :
1981
(Part 2/Sec 6) :
1981
(Part 2/Sec 7) :
1981
(Part 2/Sec 8) :
1981
2547
Title
Plaster and concrete, Section 3
Setting time of plaster and concrete
(first revision)
Plaster and concrete, Section 4
Transverse strength of gypsum
plaster (first revision)
Plaster and concrete, Section 5
Compressive strength and dry set
density of gypsum plaster (first
revision)
Plaster and concrete, Section 6
Soundness of gypsum plaster (first
revision)
Plaster and concrete, Section 7
Mechanical resistance of gypsum
plaster by dropping ball test (first
revision)
Plaster and concrete, Section 8
Freedom from coarse particles
(first revision)
Plaster and concrete, Section 9
Expansion of plaster (first revision)
Plaster and concrete, Section 10
Sand in set plaster (first revision)
Plaster and concrete, Section 1 1
Wood fibre content in gypsum
plaster (first revision)
Plaster and concrete, Section 12
Dry bulk density (first revision)
Gypsum products, Section 1
Measurement of dimensions (first
revision)
Gypsum products, Section 2
Determination of mass (first
revision)
Gypsum products, Section 3
Determination of mass and thickness
of paper surfacing (first revision)
Gypsum products, Section 4
Transverse strength (first revision)
Gypsum products, Section 5
Compressive strength (first revision)
Gypsum products, Section 6 .
Water absorption (first revision)
Gypsum products: Section 7
Moisture content (first revision)
Gypsum products, Section 8
Nail retention of precast reinforced
gypsum slabs (first revision)
Specification for gypsum building
plaster:
IS No. Title
(Part 1) : 1976 Excluding premixed lightweight
plaster (first revision)
(Part 2) : 1976 Premixed lightweight plaster (first
revision)
2849 : 1983 Specification for non-load bearing
gypsum partition blocks (solid and
hollow types)
8272: 1984 Specification for gypsum plaster or
use in the manufacture of fibrous
plasterboards (first revision)
9498 : 1980 Specification for inorganic
aggregates for use in gypsum
plaster
16. LIGNOCELLULOSIC BUILDING
MATERIALS
a) Timber and Bamboo
i) Timber Classification
399 : 1963 Classification of commercial
timbers and their zonal distribution
(revised)
1150:2000 Trade names and abbreviated
symbols for timber species (third
revision)
4970 : 1973 Key for identification of commercial
timber (first revision)
ii) Timber Conversion and Grading
190 : 1991 Specification for coniferous sawn
timber (baulks and scantlings)
(fourth revision)
1326 : 1992 Specification for non-coniferous
sawn timber (baulks and scantlings)
(second revision)
1331 : 1971 Specification for cut sizes of timber
(second revision)
3337 : 1978 Specification for bailies for general
purposes (first revision)
5966 : 1993 Specification for non-coniferous
timber in converted form for
general purpose (first revision)
14960 : 2001 Specification for preservative
treated and seasoned sawn timber
from rubberwood (Hevea
brasiliensis)
iii) Timber Testing
1708 Methods of testing small clear
specimens of timber:
(Part 1) : 1986 Determination of moisture content
(second revision)
PART 5 BUILDING MATERIALS
21
IS No.
(Part 2) : 1986
(Part 3) : 1986
(Part 4) : 1986
(Part 5) : 1986
(Part 6) : 1986
(Part 7) : 1986
(Part 8) : 1986
(Part 9) : 1986
(Part 10): 1986
(Part 11): 1986
(Part 12) : 1986
(Part 13) : 1986
(Part 14) : 1986
(Part 15): 1986
(Part 16): 1986
(Part 17) : 1986
(Part 18) : 1986
1900: 1974
2408 : 1963
2455 : 1990
2753
Title
Determination of specific gravity
(second revision)
Determination of volumetric
shrinkage (second revision)
Determination of radial and
tangential shrinkage and fibre
saturation point (second revision)
Determination of static bending
strength (second revision)
Determination of static bending
strength under two point loading
(second revision)
Determination of impact bending
strength (second revision)
Determination of compressive
strength parallel to grain (second
revision)
Determination of compressive
strength perpendicular to grain
(second revision)
Determination of hardness under
static indentation (second revision)
Determination of shear strength
parallel to grain (second revision)
Determination of tensile strength
parallel to grain (second revision)
Determination of tensile strength
perpendicular to grain (second
revision)
Determination of cleavage strength
parallel to grain (second revision)
Determination of nail and screw
holding power (second revision)
Determination of brittleness by
izod impact (second revision)
Determination of brittleness by
Charpy impact (second revision)
Determination of torsional strength
(second revision)
Method of testing wood poles (first
revision)
Methods of static tests of timbers
in structural sizes
Method of sampling of model trees
and logs for timber testing and their
conversion (second revision)
Methods for estimation of
preservatives in treated timber and
treating solutions:
IS No. Title
(Part 1) : 1991 Determination of copper, arsenic,
chromium, zinc, boron, creosote
and fuel oil (first revision)
Determination of copper (in copper
organic preservative salt) and
pentachlorophenol (first revision)
Method of testing timber connectors
Methods for evaluation of working
quality of timber under different
wood operations — Method of test
(first revision)
Methods of sampling of timber
scantlings from depots and their
conversion for testing
Methods of presentation of data of
physical and mechanical properties
of timber (first revision)
Method of determination of sound
absorption coefficient of timber by
standing wave method
Method of determination of thermal
conductivity of timber
Methods for determination of
moisture content of timber and
timber products (first revision)
Method of test for determination of
dielectric constant of wood under
microwave frequencies
iv) Structural Timber and Test
Specification for structural timber
in building (first revision)
Specification for preferred cut sizes
of structural timber (first revision)
4924 Method of test for nail jointed
timber trusses:
Destructive test
Proof test
(Part 2) : 1991
4907 : 1968
8292 : 1992
8720 : 1978
8745 : 1994
10420 : 1982
10754 : 1983
11215: 1991
13621 : 1993
3629 : 1986
4891 : 1988
(Part 1) : 1968
(Part 2) : 1968
v) Logs
3364
(Part 1) : 1976
(Part 2) : 1976
4895 : 1985
5246 : 2000
7308 : 1999
Method of measurement and
evaluation of defects in timber:
Logs (first revision)
Converted timber (first revision)
Specification for teak logs (first
revision)
Specification for coniferous logs
(first revision)
Specification for non-coniferous
logs (first revision)
22
NATIONAL BUILDING CODE OF INDIA
IS No.
vi) Bamboo
6874 : 1973
8242 : 1976
b) Reconstituted
i) Plywood
303 : 1989
1328: 1996
1734
(Part 1): 1983
(Part 2): 1983
(Part 3): 1983
(Part 4) : 1983
(Part5): 1983
(Part 6) : 1983
(Part 7) : 1983
(Part 8): 1983
(Part 9): 1983
(Part 10: 1983
(Part 11): 1983
(Part 12) : 1983
(Part 13) : 1983
(Part 14) : 1983
(Part 15): 1983
(Part 16): 1983
(Part 17) : 1983
(Part 18): 1983
(Part 19) : 1983
Title
Method of tests for round bamboos
Methods of tests for split bamboos
Products
Specification for plywood for
general purposes (third revision)
Specification for veneered
decorative plywood (third revision)
Method of test for plywood:
Determination of density and
moisture content (second revision)
Determination of resistance of dry
heat (second revision)
Determination of fire resistance
(second revision)
Determination of glue shear strength
(second revision)
Test for adhesion of plies (second
revision)
Determination of water resistance
(second revision)
Mycological test (second revision)
Determination of pH value (second
revision)
Determination of tensile strength
(second revision)
Determination of compressive
strength (second revision)
Determination of static bending
strength (second revision)
Determination of scarf joint
strength (second revision)
Determination of panel shear
strength (second revision)
Determination of plate shear
strength (second revision)
Central loading of plate test
(second revision)
Vibration of plywood plate test
(second revision)
Long time loading test of plywood
strips (second revision)
Impact resistance test on the
surface of plywood (second
revision)
Determination of nails and screws
holding power (second revision)
IS No.
(Part 20) : 1983
4990 : 1993
5509 : 2000
5539 : 1969
7316:
1974
10701
: 1983
13957
: 1994
Title
Acidity and alkalinity resistance
test (second revision)
Specification for plywood for
concrete shuttering work (second
revision)
Specification for fire retardant
plywood (second revision)
Specification for preservative
treated plywood
Specification for decorative
plywood using plurality of veneers
for decorative faces
Specification for structural plywood
Specification for metal faced
plywood
ii) Blockboards, Particle Boards and Fibre Boards
1658 : 1977 Specification for fibre hardboards
(second revision)
Specification for block boards
(third revision)
Methods of test for wood particle
boards and boards from other
lignocellulosic materials:
Preparation and conditioning of
test specimens (first revision)
Accuracy of dimensions of boards
(first revision)
Determination of moisture content
and density (first revision)
Determination of static bending
strength (first revision)
Determination of tensile strength
perpendicular to surface (first
revision)
Determination of tensile strength
parallel to surface (first revision)
Determination of compression —
Perpendicular to plane of the board
(first revision)
Compression parallel to surface
test (first revision)
Determination of resistance to
shear in plane of the board (first
revision)
Falling hammer impact test (first
revision)
Surface hardness (first revision)
Central loading of plate test (first
revision)
1659 : 1990
2380
(Part 1) : 1977
(Part 2) : 1977
(Part 3) : 1977
(Part 4) : 1977
(Part 5) : 1977
(Part 6) : 1977
(Part 7) ■: 1977
(Part 8) : 1977
(Part 9) : 1977
(Part 10) : 1977
(Part 11): 1977
(Part 12) : 1977
PART 5 BUILDING MATERIALS
23
IS No.
(Part 13): 1977
(Part 14) : 1977
(Part 15) : 1977
(Part 16) : 1977
(Part 17) : 1977
(Part 18): 1977
(Part 19) : 1977
(Part 20) : 1977
(Part 21) : 1977
(Part 22) : 1981
(Part 23): 1981
3087 : 1985
3097 : 1980
3129 : 1985
3308: 1981
3348 : 1965
3478 : 1966
12406 : 2003
12823 : 1990
13745 : 1993
14276 : 1995
14587 : 1998
Title
Long time loading bending test
(first revision)
Screw and nail withdrawal test
(first revision)
Lateral nail resistance (first
revision)
Determination of water absorption
(first revision)
Determination of swelling in water
(first revision)
Determination of mass and
dimensional changes caused by
moisture changes (first revision)
Durability cyclic test for interior
use (first revision)
Accelerated weathering cyclic test
for exterior use (first revision)
Planeness test under uniform
moisture content (first revision)
Determination of surface glueability
test
Vibration test for particle boards
Specification for wood particle
boards (medium density) for
general purposes (first revision)
Specification for veneered particle
boards (first revision)
Specification for low density
particle board (first revision)
Specification for wood wool
building slabs (first revision)
Specification for fibre insulation
boards
Specification for high density
wood particle boards
Specification for medium density
fibreboards for general purposes
(first revision)
Specification for prelaminated
particle boards
Method for determination of
formaldehyde content in particle
board by extraction method called
perforator method
Specification for cement bonded
particle boards
Specification for prelaminated
medium density fibre board
IS No.
iii) Wood-Based Laminates
Title
3513 (Part 3):
1989
3513 (Part 4):
1966
7638: 1998
9307
(Part 1) : 1979
(Part 2) : 1979
(Part 3) : 1979
(Part 4) : 1979
(Part 5) : 1979
(Part 6) : 1979
(Part 7) : 1979
(Part 8) : 1979
14315 : 1995
14616 : 1999
Specification for resin treated
compressed wood laminates
(compregs): Part 3 For general
purposes (first revision)
Specification for high and medium
density wood laminates (compreg):
Part 4 Sampling and tests
Methods of sampling for wood/
lignocellulosic based panel products
Methods of tests for wood-based
structural sandwich construction:
Flexure test
Edgewise compression test
Flatwise compression test
Shear test
Flatwise tension test
Flexure creep test
Cantilever vibration test
Weathering test
Specification for commercial
veneers
Specification for laminated veneer
lumber
iv) Bamboo and Coir Board Products
13958 : 1994 Specification for bamboo mat
board for general purposes
14588 : 1999 Specification for bamboo mat
veneer composite for general
purposes
14842 : 2000 Specification for coir veneer board
for general purposes
15476:2004 Specification for bamboo and
corrugated sheets
v) Adhesives
848 : 1974 Specification for synthetic resin
adhesives for plywood (phenolic
and aminoplastic) (first revision)
849 : 1994 Specification for cold setting case
in glue for wood (first revision)
851 : 1978 Specification for synthetic resin
adhesives for construction work
(non-structural) in wood (first
revision)
852 : 1994 Specification for animal glue for
general wood-working purposes
(second revision)
24
NATIONAL BUILDING CODE OF INDIA
IS No, Title
1508 : 1972 Specification for extenders for use
in synthetic resin adhesives (urea-
formaldehyde) for plywood (first
revision)
4835 : 1979 Specification for polyvinyl acetate
dispersion-based adhesives for
wood (first revision)
9188 : 1979 Performance requirements for
adhesive for structural laminated
wood products for use under
exterior exposure condition
17, PAINTS AND ALLIED PRODUCTS
a) Water Based Paints and Pigments
427 : 1965 Specification for distemper, dry,
colour as required (revised)
428 : 2000 Specification for distemper,
washable (second revision)
5410 : 1992 Specification for cement paint,
colour as required (first revision)
5411 Specification for plastic emulsion
paint:
(Part 1) : 1974 For interior use (first revision)
(Part 2) : 1972 For exterior use
b) Ready Mixed Paints, Enamels and Powder
Coatings
101
(Part l/Sec 1) :
1986
(Part l/Sec 2) :
1987
(Part l/Sec 3) :
1986
(Part l/Sec 4) :
1987
(Part l/Sec 5) :
1989
(Part l/Sec 6) :
1987
Methods of sampling and test for
paints, varnishes and related
products:
Test on liquid paints (general
and physical), Section 1 Sampling
(third revision)
Test on liquid paints (general
and physical), Section 2 Preliminary
examination and preparation
of samples for testing (third
revision)
Test on liquid paints (general and
physical), Section 3 Preparation of
panels (third revision)
Test on liquid paints (general and
physical), Section 4 Brushing test
(third revision)
Test on liquid paints (general and
physical), Section 5 Consistency
(third revision)
Test on liquid paints (general and
physical), Section 6 Flash point
(third revision)
IS No.
(Part l/Sec 7) :
1987
(Part2/Secl):
1988
(Part 2/Sec 2) ;
1986
(Part 3/Sec 1) ;
1986
(Part 3/Sec 2) :
1989
(Part 3/Sec 4) ;
1987
(Part 3/Sec 5) :
1987
(Part4/Sec 1) :
1988
(Part 4/Sec 2) :
1989
(Part 4/Sec 3) :
1988
(Part 4/Sec 4) :
1986
(Part 5/Sec 1) :
1988
(Part 5/Sec 2) :
1988
(Part 5/Sec 3) :
1986
(Part 5/Sec 4) :
1986
(Part 6/Sec 1) :
1988
(Part 6/Sec 2) :
1989
(Part 6/Sec 3) :
1990
Title
Test on liquid paints (general and
physical), Section 7 Mass per
10 litres (third revision)
Test on liquid paints (chemical
examination), Section 1 Water
content (third revision)
Test on liquid paints (chemical
examination), Section 2 Volatile
matter (third revision)
Tests on paint film formation,
Section 1 Drying time (third
revision)
Tests on paint film formation,
Section 2 Film thickness (third
revision)
Tests on paint film formation,
Section 4 Finish (third revision)
Tests on paint film formation,
Section 5 Fineness of grind (third
revision)
Optical test, Section 1 Opacity
(third revision)
Optical test, Section 2 Colour
(third revision)
Optical test, Section 3 Light
fastness test (third revision)
Optical test, Section 4 Gloss (third
revision)
Mechanical test on paint films,
Section 1 Hardness tests (third
revision)
Mechanical test on paint films,
Section 2 Flexibility and adhesion
(third revision)
Mechanical test on paint films,
Section 3 Impact resistance (fourth
revision)
Mechanical test on paint films,
Section^ Print free test (third
revision)
Durability tests, Section 1
Resistance to humidity under
conditions of condensation (third
revision)
Durability tests, Section 2 Keeping
properties (third revision)
Durability tests, Section 3 Moisture
vapour permeability (third
revision)
PART 5 BUILDING MATERIALS
25
IS No. Title
(Part 6/Sec 4) : Durability tests, Section 4
1991 Degradation of coatings (pictorial
aids for evaluation)
(Part 6/Sec 5) : Durability tests, Section 5
1997 Accelerated weathering test (third
revision)
(Part 7/Sec 1) : Environmental tests on paint films,
1989 Section 1 Resistance to water (third
revision)
(Part 7/Sec 2) : Environmental tests on paint films,
1990 Section 2 Resistance to liquids
(third revision)
(Part 7/Sec 3) : Environmental tests on paint films,
1990 Section 3 Resistance to heat (third
revision)
(Part 7/Sec 4) : Environmental tests on paint films,
1 990 Section 4 Resistance to bleeding of
pigments (third revision)
(Part 8/Sec 1) : Tests for pigments and other
1989 solids, Section 1 Residue on sieve
(third revision)
(Part 8/Sec 2) : Tests for pigments and other
1 990 solids, Section 2 Pigments and non-
volatile matter (third revision)
(Part 8/Sec 3) : Tests for pigments and other
1993 solids, Section 3 Ash content
(Part 8/Sec 4) : Tests for pigments and other
1 993 solids, Section 4 Phthalic anhydride
(Part 8/Sec 5) : Tests for pigments and other
1993 solids, Section 5 Lead restriction
test (third revision)
(Part 8/Sec 6) : Tests for pigments and other
1993 solids, Section 6 Volume solids
(Part 9/Sec 1) : Tests for lacquers and varnish,
1993 Section 1 Acid value
(Part 9/Sec 2) : Tests for lacquers and varnish,
1993 Section 2 Rosin test
104 : 1979 Specification for ready mixed
paint, brushing, zinc chrome,
priming (second revision)
109 : 1968 Specification for ready mixed
paint, brushing, priming, plaster to
Indian Standard colours No. 361
and 631 (first revision)
123 : 1962 Specification for ready mixed
paint, brushing, finishing, semi-
gloss, for general purposes, to
Indian Standard colours No. 445,
446, 448, 449, 451 and 473; and
red oxide (colour unspecified)
(revised)
IS No. Title
133 : 1993 Specification for enamel, interior
(a) undercoating, (b) finishing
(third revision)
137 : 1965 Specification for ready mixed
paint, brushing, matt or egg-shell
flat, finishing, interior, to Indian
Standard colour, as required
(revised)
158 : 1981 Specification for ready mixed
paint, brushing, bituminous, black,
lead-free, acid, alkali, and heat
resisting (third revision)
168 : 1993 Specification for ready mixed
paint, air-drying semi-glossy/matt,
for general purposes (third
revision)
341 : 1973 Specification for black Japan,
Types A, B and C (first revision)
2074 : 1992 Specification for ready mixed
paint, air drying red oxide-zinc
chrome, priming (second revision)
2075 : 2000 Specification for ready mixed paint,
stoving, red oxide-zinc chrome,
priming (second revision)
2339 : 1963 Specification for aluminium paint
for general purposes, in dual
container
2932 : 2003 Specification for enamel, synthetic,
exterior, (a) undercoating, (b)
finishing (third revision)
2933 : 1975 Specification for enamel, exterior,
(a) undercoating, (b) finishing (first
revision)
3536 : 1999 Specification for ready mixed
paint, brushing, wood primer (first
revision)
3537 : 1966 Specification for ready mixed
paint, finishing, interior for general
purposes, to Indian Standard
colours No. 101, 216, 217, 219,
275/281, 352, 353, 358 to 361,
363, 364, 388, 410, 442, 444, 628,
631, 632, 634, 693, 697, white and
black
3539 : 1966 Specification for ready mixed
paint, undercoating, for use under
oil finishes, to Indian Standard
colours, as required
3585 : 1966 Specification for ready mixed paint,
aluminium, brushing, priming,
water resistant, for wood work
26
NATIONAL BUILDING CODE OF INDIA
IS No. Title
3678 : 1966 Specification for ready mixed
paint, thick white, for lettering
8662 : 1993 Specification for enamel, synthetic,
exterior, (a) undercoating,
(b) finishing, for railway coaches
(first revision)
9862 : 1981 Specification for ready mixed
paint, brushing, bituminous black
lead free, acid, alkali, water and
chlorine resisting
11883 : 1986 Specification for ready mixed
paint, brushing, red oxide, priming
for metals
13183 : 1991 Specification for aluminium paints,
heat resistant
13213 : 1991 Specification for polyurethane full
gloss enamel (two pack)
13607 : 1992 Specification for ready mixed
paint, finishing, general purposes,
synthetic
13871 : 1993 Specification for powder coatings
c) Thinners and Solvents
82 : 1992 Methods of sampling and test for
thinners and solvents for paints
(first revision)
324: 1959 Specification for ordinary
denatured spirit (revised)
533 : 1998 Specification for gum spirit of
turpentine (oil of turpentine)
(second revision)
14314 : 1995 Specification for thinner general
purposes for synthetic paints and
varnishes
d) Varnishes and Lacquers
337 : 1975 Specification for varnish, finishing,
interior (first revision)
347 : 1975 Specification for varnish, shellac,
for general purposes (first revision)
348 : 1968 Specification for French polish
(first revision)
524 : 1983 Specification for varnish, finishing,
exterior, synthetic (second revision)
525 : 1968 Specification for varnish, finishing,
exterior and general purposes (first
revision)
642 : 1963 Specification for varnish medium
for aluminium paint (revised)
IS No.
Title
18. POLYMERS, PLASTICS AND
GEOSYNTHETICS/GEOTEXTILES
1998 : 1962
2036 : 1995
2046 : 1995
2076: 1981
2508 : 1984
6307 : 1971
9766 : 1992
10889 : 1984
12830 : 1989
13162
(Part 2) : 1991
(Part 3) : 1992
(Part 4) : 1992
(Part 5) : 1992
13262 : 1992
13325 : 1992
13326 (Part 1) :
1992
14182 : 1994
Methods of test for thermosetting
synthetic resin bonded laminated
sheets
Specification for phenolic
laminated sheets (second revision)
Specification for decorative
thermosetting synthetics resin
bonded laminated sheets (second
revision)
Specification for unsupported
flexible vinyl film and sheeting
(first revision)
Specification for low density
polyethylene films (second
revision)
Specification for rigid PVC sheets
Specification for flexible PVC
compound (first revision)
Specification for high density
polyethylene films
Specification for rubber based
adhesives for fixing PVC tiles to
cement
Methods of test for geotextiles:
Determination of resistance to
exposure of ultra-violet light and
water (Xenon arc type apparatus)
Determination of thickness at
specified pressure
Determination of puncture
resistance by falling cone method
Determination of tensile properties
using a wide width strip
Specification for pressure sensitive
adhesive tapes with plastic base
Method of test for the determination
to tensile properties of extruded
polymer geogrids using the wide
strip
Method of test for the evaluation
of interface friction between
geosynthetics and soil: Part 1
Modified direct shear technique
Specification for solvent cement
for use with unplasticized
polyvinylchloride plastic pipe and
fittings
PART 5 BUILDING MATERIALS
27
IS No.
Title
IS No.
Title
14293 : 1995
14294 : 1995
14324 : 1995
14443 : 1997
14643 : 1999
14706 : 1999
14714 : 1999
14715 : 2000
14716: 1999
14739 : 1999
14753 : 1999
14986 : 2001
15060 : 2001
19. SANITARY
FITTINGS
a) General
775 : 1970
782 : 1978
804 : 1967
1700 : 1973
2963 : 1979
3489 : 1985
Method of test for trapezoid tearing 5219 (Part 1) :
— Geotextiles 1969
Method of determination of 5455 : 1969
apparent opening size by dry
sieving technique — Geotextiles 6411 : 1985
Method of test for determination of
water permeability-permittivity —
Geotextiles 87 i 8 . i 97 g
Specification for polycarbonate
sheets 872 7 ; 1978
Specification for unsintered
polytetrafluoroethylene (PTFE) 9140 . 1995
tape for thread sealing applications
Sampling and preparation of test
specimen of geotextiles 12701 : 1996
Determination of abrasion
resistance of geotextiles
Specification for woven jute 13983 : 1994
geotextiles
Determination of mass per unit area 14399
of geotextiles
Methods for determination of creep
of geotextiles (Part 1): 1996
Specification for poly (methyl) (Part 2) : 1996
methacrylate (PMMA) (Acrylic)
sheets
Jute geo-grid for rain water erosion
control in road and railway
embankments and hill slopes
Tensile test for joints/seams by
wide width method of geotextiles 2501 : 1995
APPLIANCES AND WATER
Specification for cast copper alloy
traps: Part 1 T' and 'S' traps
Specification for cast-iron steps for
manholes
Specification for gel-coated glass
fibre reinforced polyester resin
bath tubs {first revision)
Specification for vitreous
enamelled steel kitchen sinks
Specification for vitreous
enamelled steel wash basins
Method of sampling of vitreous
and fire clay sanitary appliances
{second revision)
Specification for rotational moulded
polyethylene water storage tanks
(first revision)
Specification for stainless steel
sinks for domestic purposes
Hot press moulded thermosetting
glass fibre reinforced (GRP)
sectional water storage tanks:
Specification for panels
Guidelines for assembly, installation
and testing
b) Pipes and Fittings Excluding Valves
i) Brass and Copper Pipes and Fittings
407 : 1981
Specification for brass tubes for
general purposes {third revision)
Specification for solid drawn
copper tubes for general engineering
purposes {third revision)
ii) Cast Iron Pipes and Fittings
Specification for cast iron brackets 1 536 : 2001
and supports for wash basins and
sinks (second revision)
Specification for caulking lead
(third revision) 1537 : 1976
Specification for rectangular
pressed steel tanks (first revision)
Specification for drinking 1538 : 1993
fountains (first revision)
Specification for copper alloy
waste fittings for wash-basins and 1729 : 2002
sinks (first revision)
Specification for enamelled steel
bath tubs (first revision)
Specification for centrifugally cast
(spun) iron pressure pipes for
water, gas and sewage (fourth
revision)
Specification for vertically cast
iron pressure pipes for water, gas
and sewage (first revision)
Specification for cast iron fittings
for pressure pipes for water, gas
and sewage (third revision)
Specification for sand cast iron
spigot and socket soil, waste and
ventilating pipes, fittings and
accessories (second revision)
28
NATIONAL BUILDING CODE OF INDIA
IS No.
1879:
: 1987
3486:
: 1966
3989:
: 1984
5531 : 1988
6163 : 1978
6418 : 1971
7181 : 1986
8329 : 2000
8794 : 1988
9523 : 1980
10292 : 1988
10299 : 1982
11606: 1986
12820: 1989
12987: 1991
Title
Specification for malleable cast
iron pipe fittings (second revision)
Specification for cast iron spigot
and socket drain pipes
Specification for centrifugally cast
(spun) iron spigot and socket
soil, waste and ventilating pipes,
fittings and accessories (second
revision)
Specification for cast iron specials
for asbestos cement pressure pipes
for water, gas and sewage (second
revision)
Specification for centrifugally cast
(spun) iron low pressure pipes
for water, gas and sewage (first
revision)
Specification for cast iron and
malleable cast iron flanges for
general engineering purposes
Specification for horizontally cast
iron double flanged pipes for water,
gas and sewage (first revision)
Specification for centrifugally cast
(spun) ductile iron pressure pipes
for water, gas and sewage (third
revision)
Specification for cast iron
detachable joints for use with
asbestos cement pressure pipes
(first revision)
Specification for ductile iron
fittings for pressure pipes for water,
gas and sewage
Dimensional requirements for
rubber sealing rings for CID joints
in asbestos cement piping (first
revision)
Cast iron saddle pieces for service
connection from asbestos cement
pressure pipes
Methods of sampling cast iron
pipes and fittings
Dimensional requirements of
rubber gaskets for mechanical
joints and push on joints for use
with cast iron pipes and fittings for
carrying water, gas and sewage
Cast iron detachable joints for use
with asbestos cement pressure
pipes (light duty)
IS No. Title
12988 : 1991 Rubber sealing rings for CID
joints for light duty AC pipes —
Dimensional requirements
13382 : 1992 Cast iron specials for mechanical
and push on flexible joints for
pressure pipelines for water, gas
and sewage
iii) Lead Pipes and Fittings
404 (Part 1) ': Specification for lead pipes: Part 1
1993 For other than chemical purpose
(third revision)
iv) Fibre Pipes and Fittings
11925 : 1986 Specification for pitch-
impregnated fibre pipes and fittings
for drainage purposes
v) Plastic Pipes and Fittings
3076 : 1985 Specification for low density
polyethylene pipes for potable
water supplies (second revision)
4984 : 1995 Specification for high density
polyethylene pipes for water
supply (fourth revision)
4985 : 2000 Specification for unplasticized
PVC pipes for potable water
supplies (third revision)
7834 Specification for injection moulded
PVC socket fittings with solvent
cement joints for water supplies:
(Part 1) : 1987 General requirements (first revision)
(Part 2) : 1987 Specific requirements for 45°
elbows (first revision)
(Part 3) : 1987 Specific requirements for 90°
elbows (first revision)
(Part 4) : 1987 Specific requirements for 90° tees
(first revision)
(Part 5) : 1987 Specific requirements for 45° tees
(first revision)
(Part 6) : 1987 Specific requirements for sockets
(first revision)
(Part 7) : 1987 Specific requirements for unions
(first revision)
(Part 8) : 1987 Specific requirements for caps
(first revision)
8008 Specification for injection moulded
high density polyethylene (HDPE)
fittings for potable water supplies:
(Part 1) : 2003 General requirements
PART 5 BUILDING MATERIALS
29
IS No.
(Part 2) : 2003
(Part 3) : 2003
(Part 4) : 2003
(Part 5) : 2003
(Part 6) : 2003
(Part 7) : 2003
(Part 8) : 2003
(Part 9) : 2003
8360
(Part 1) : 1977
(Part 2) : 1977
(Part 3) : 1977
10124
(Part 1) : 1988
(Part 2) : 1988
(Part 3) : 1988
(Part 4) : 1988
(Part 5) : 1988
(Part 6) : 1988
(Part 7) : 1988
(Part 8): 1988
(Part 9) : 1988
(Part 10) : 1988
(Part 11): 1988
(Part 12) : 1988
(Part 13): 1988
Title
Specific requirements for 90°
bends {first revision)
Specific requirements for 90° tees
Specific requirements for reducers
Specific requirements for ferrule
reducers (first revision)
Specific requirements for pipe ends
Specific requirements for sandwich
flanges
Specific requirements for reducing
tests
Specific requirements for end caps
(first revision)
Specification for fabricated high
density polyethelene (HDPE)
fittings for potable water supplies:
General requirements
Specific requirements for 90° tees
Specific requirements for 90°
bends
Specification for fabricated PVC
fittings for potable water supplies:
General requirements (first revision)
Specific requirements for sockets
(first revision)
Specific requirements of straight
reducers (first revision)
Specific requirements for caps
(first revision)
Specific requirements for equal
tees (first revision)
Specific requirements for flanged
tail piece with metallic flanges
(first revision)
Specific requirements for threaded
adaptors (first revision)
Specific requirements for 90°
bends (first revision)
Specific requirements for 60°
bends (first revision)
Specific requirements for 45°
bends (first revision)
Specific requirements for 30°
bends (first revision)
Specific requirements for 22V2°
bends (first revision)
Specific requirements for \\ l A°
bends (first revision)
IS No. Title
12235 Methods of test for unplasticized
PVC pipes for potable water
supplies:
(Part 1) : 1986 Method of measurement of outside
diameter
1986 Measurement of wall thickness
1986 Test for opacity
1986 Determining the detrimental effect
on the composition of water
Reversion test
Stress relief test
Test for resistance to sulphuric acid
Internal hydrostatic pressure test
Impact strength test
Method for determination of
organotin as tin aqueous solution
Extractability of cadmium and
mercury occurring as impurities
Specification for glass-fibre
reinforced plastic (GRP) pipes
joints and fittings for use for
potable water supply (first revision)
Specification for unplasticized
PVC screen and casing pipes for
bore/tubewell (first revision)
Specification for UPVC pipes for
soil and waste discharge systems
inside buildings including
ventilation and rainwater system
Specification for high density
polyethylene pipes for sewerage
Specification for GRP pipes, joints
and fittings for use for sewerage,
industrial waste and water (other
than potable)
Specification for unplasticized
polyvinyl chloride (UPVC)
injection moulded fittings for soil
and waste discharge system for
inside buildings including
ventilation and rain water system
14885 : 2001 Specification for polyethylene pipe
for supply of gaseous fuel
15225 : 2002 Specification for chlorinated
polyvinyl chloride compounds
used for pipes and fittings
15328 : 2003 Specification for unplasticized
non-pressure polyvinyl chloride
(PVC-U) pipes for use in
underground drainage and sewerage
system
(Part 2)
(Part 3)
(Part 4)
(Part 5) : 1986
(Part 6) : 1986
(Part 7) : 1986
(Part 8) : 1986
(Part 9) : 1986
(Part 10) : 1986
(Part 11): 1986
12709 : 1994
12818 : 1992
13592: 1992
14333 : 1996
14402 : 1996
14735 : 1999
30
NATIONAL BUILDING CODE OF INDIA
IS No.
vi) Steel Tubes,
1239
(Part 1) : 1990
(Part 2) : 1992
3589 : 1991
4270 : 1992
5504: 1997
6286 : 1979
6392 : 1971
Title
Pipes and Fittings
Mild steel tubes, tubular and other
wrought steel fittings:
Mild steel tubes (fifth revision)
Mild steel tubular and other
wrought steel pipe fittings (third
revision)
Specification for seamless or
electrically welded steel pipes for
water, gas and sewage (168.3 to
2 032 mm outside size) (second
revision)
Steel tubes used for water wells
(second revision)
Specification for spiral welded
pipes (first revision)
Seamless and welded steel pipe for
sub-zero temperature service
Steel pipe flanges
vii) Stoneware Pipes and Fittings
651 : 1992
3006 : 1979
Specification for salt-glazed
stoneware pipes and fittings (fifth
revision)
Specification for chemically
resistant glazed stoneware pipes
and fittings (first revision)
viii) Asbestos Cement Pipes
[See 8 (a) (ii) under the category 'Composite Matrix
Products']
ix) Concrete Pipes and Pipes Lined/Coated with
Concrete or Mortar
[See 8 (a) (iv) under the category 'Composite Matrix
Products']
c) Kitchen and Sanitary Appliances
771 Specification for glazed fire clay
sanitary appliances:
(Part 1) : 1979 General requirements (second
revision)
(Part 2) : 1985 Specific requirements of kitchen
and laboratory sinks (third revision)
(Part 3/Sec 1) : Specific requirements of urinals,
1979 Section 1 Slab urinals (second
revision)
(Part 3/Sec 2) : Part 3 Specific requirements of
1985 urinals, Section 2 Stall urinals
(third revision)
IS No.
(Part 4) : 1979
(Part 5) : 1979
(Part 6) : 1979
(Part 7) : 1981
772 : 1973 ,
773 : 1988
774 : 1984
1726 : 1991
2326: 1987
2548
(Part 1) : 1996
(Part 2) : 1996
2556
(Part 1) : 1994
(Part 2) : 1994
(Part 3) : 1994
(Part 4) : 1994
(Part 5) : 1994
(Part 6) : 1995
(Part 7) : 1995
(Part 8) : 1995
Title
Specific requirements of post
mortom slabs (second revision)
Specific requirements of shower
trays (second revision)
Specific requirements of bed-pan
sinks (second revision)
Specific requirements of slop sinks
(second revision)
Specification for general
requirements of enamelled cast
iron sanitary appliances (second
revision)
Specification for enamelled cast
iron water-closets railway stock
type (fourth revision)
Specification for flushing cisterns
for water-closets and urinals (other
than plastic cisterns) (fourth revision)
Specification for cast iron manhole
covers and frames (third revision)
Specification for automatic flushing
cisterns for urinals (second
revision)
Specification for plastic seats and
covers for water-closets:
Thermoset seats and covers (fifth
revision)
Thermoplastic seats and covers
(fifth revision)
Specification for vitreous sanitary
appliances (vitreous china):
General requirements (third
revision)
Specific requirements of wash-
down water-closets (fourth
revision)
Specific requirements of squatting
pans (fourth revision)
Specific requirements of wash
basins (third revision)
Specific requirements of laboratory
sinks (third revision)
Specific requirements of urinals
and partition plates (fourth revision)
Specific requirements of accessories
for sanitary appliances (third
revision)
Specific requirements of siphonic
wash-down water closets (fourth
revision)
PART 5 BUILDING MATERIALS
31
IS No.
(Part 9) : 1995
Title
Specific requirements of bidets
(fourth revision)
(Part 14): 1995 Specific requirements of integrated
squatting pans (first revision)
(Part 15) : 1995 Specific requirements of universal
water closets (first revision)
(Part 16) : 2002 Specific requirements for wash
down wall mounted water-closets
(Part 17) : 1995 Specific requirements for wall
mounted bidets
5961 : 1970 Specification for cast iron gratings
for drainage purposes
7231 : 1984 Specification for plastic flushing
cisterns for water-closets and
urinals (second revision)
11246:1992 Specification for glass fibre
reinforced polyester resins (GRP)
squatting pans (first revision)
d) Valves and Fittings (Including Ferrules)
778 : 1984 Specification for copper alloy gate,
globe, and check valves for water
works purposes (fourth revision)
781 : 1984 Specification for cast copper alloy
screw-down bib taps and stop
valves for water services (third
revision)
1701 : 1960 Specification for mixing valves
for ablutionary and domestic
purposes
1 703 : 2000 Specification for copper alloy float
valves (horizontal plunger type)
for water supply fittings (third
revision)
1711 : 1984 Specification for self-closing taps
for water supply purposes (second
revision)
1795 : 1982 Specification for pillar taps for
water supply purposes (second
revision)
2692 : 1 989 Specification for ferrules for water
services (second revision)
3004 : 1979 Specification for plug cocks for
water supply purposes (first
revision)
3042 : 1965 Specification for single faced
sluice gates (200 to 1 200 mm size)
3311 : 1979 Specification for waste plug and
its accessories for sinks and
washbasins (first revision)
IS No.
3950:
: 1979
4038:
: 1986
4346:
: 1982
5312
(Part 1) : 1984
(Part 2) : 1986
8931 : 1993
9338 : 1984
9739: 1981
9758 : 1981
9762 : 1994
9763 : 2000
12234 : 1988
13049 : 1991
13114: 1991
14845 : 2000
14846 : 2000
e) Water Meters
779 : 1994
Title
Specification for surface boxes for
sluice valves (first revision)
Specification for foot valves for
water works purposes (second
revision)
Specification for washers for use
with fittings for water services (first
revision)
Specification for swing check type
reflux (non-return) valves:
Single door pattern (first revision)
Multi-door pattern
Specification for cast copper alloy
fancy single tap combination tap
and stop valves for water services
(first revision)
Specification for cast iron screw-
down stop valves and stop and
check valves for water works
purposes (first revision)
Specification for pressure reducing
valves for domestic water supply
systems
Specification for flush valves and
fittings for water-closets and urinals
Specification for polyethylene
floats (spherical) for float valves
(first revision)
Specification for plastic bib taps,
pillar taps, angle valves, hot and
cold water services (second revision)
Specification for plastic
equilibrium float valve for cold
water services
Specification for diaphragm type
(plastic body) float operated valves
for cold water services
Specification for forged brass gate,
globe aiid check valves for water
works purposes
Specification for resilient seated
cast iron air relief valves for water
works purposes
Specification for sluice valves
for water works purposes (50 to
1 200 mm)
Specification for water meters
(domestic type) (sixth revision)
32
NATIONAL BUILDING CODE OF INDIA
IS No.
Title
IS No.
2104: 1981
Specification for water meter boxes
(domestic type) (first revision)
8500 : 1991
2373 : 1981
Specification for water meters
(bulk type) (third revision)
8952 : 1995
6784 : 1996
Method for performance testing of
water meters (domestic type)
(second revision)
20. SOIL-BASED PRODUCTS
1725 : 1982 Specification for soil-based blocks
used in general building
construction
21. STEEL AND ITS ALLOYS
a) General
1030 : 1998 Carbon steel castings for general
engineering purposes (fifth
revision)
1136 : 1990 Preferred sizes for wrought metal
products (first revision)
1137 : 1990 Thickness of sheet and diameters
of wire (first revision)
1762 (Part 1) : Code for designation of steels:
1 974 Part 1 Based on letter symbols (first
revision)
2049 : 1978 Colour code for the identification
of wrought steel for general
engineering purposes (first
revision)
2644 : 1994 High tensile steel castings (fourth
revision)
7598 : 1990 Classification of steels (first revision)
b) Structural Steel
1977 : 1996 Specification for low tensile
structural steels (third revision)
2062 ; 1999 Specification for steel for general
structural purposes (fifth revision)
2830: 1992 Specification for carbon steel
billets ingots, blooms and slabs for
re-rolling into steel for general
structural purposes (second
revision)
2831 : 2000 Specification for carbon steel
billets ingots, blooms and slabs for
re-rolling into low tensile structural
steel (third revision)
8053 : 1976 Specification for steel ingots and
billets for the production of steel
wire for the manufacture of wood
screws
9467 : 1980
c) Sheet and
277 : 2003
412 : 1975
513 : 1994
1079 : 1994
6911 : 1992
7226 : 1974
11587: 1986
14246 : 1995
15103 : 2002
Title
Specification for structural steels
microalloyed (medium and high
strength qualities)
Steel ingots, blooms and billets for
production of mild steel wire rods
for general engineering purposes
(first revision)
Steel ingots and billets for
production of rivet bars for
structural purposes
Strip
Specification for galvanized steel
sheets (plain and corrugated) (sixth
revision)
Specification for expanded metal
steel sheets for general purposes
(second revision)
Specification for cold rolled low
carbon steel sheets and strips
(fourth revision)
Specification for hot rolled carbon
steel sheet and strip (fifth revision)
Stainless steel plate, sheet and strip
(first revision)
Specification for cold rolled
medium, high carbon and low alloy
steel strip for general engineering
purposes
Specification for structural weather
resistant steels
Specification for continuously pre-
painted galvanized steel sheets and
coils
Specification for fire resistant
steel
d) Bars, Rods, Wire and Wire Rods
280: 1978 Specification for mild steel wire for
general engineering purposes
(third revision)
1148 : 1982 Specification for hot rolled steel
rivet bars (up to 40 mm diameter)
for structural purposes (third
revision)
1149 : 1982 Specification for high tensile steel
rivet bars for structural purposes
(third revision)
1673 : 1984 Specification for mild steel wire
cold heading quality (second
revision)
PART 5 BUILDING MATERIALS
33
IS No.
1812: 1982
1835 : 1976
2591 : 1982
3150: 1982
4826: 1979
6527 : 1995
6528 : 1995
6603 : 2001
7887 : 1992
10631 : 1983
e) Plates
3502 : 1994
Title
Specification for carbon steel wire
for the manufacture of wood screw
(second revision)
Specification for round steel wire
for ropes (third revision)
Dimensions for hot rolled bars for
threaded components (second
revision)
Specification for hexagonal wire
netting for general purposes
Specification for hot-dipped
galvanized coatings on round steel
wires (first revision)
Stainless steel wire rod (first
revision)
Specification for stainless steel
wire (first revision)
Specification for stainless steel bars
and flats (first revision)
Specification for mild steel wire
rods for general engineering
purposes (first revision)
Stainless steel for welding
electrode core wire
Specification for steel chequered
plates (second revision)
f) Tubes and Tubulars
1161 : 1998 Specification for steel tubes
for structural purposes (fourth
revision)
4516 : 1968 Specification for elliptical mild
steel tubes
4923 : 1997 Specification for hollow mild steel
sections for structural use (first
revision)
g) Slotted Sections
8081 : 1976 Specification for slotted sections
22. STONES
1121
(Part 1): 1974
(Part 2) : 1974
(Part 3) : 1974
(Part 4) : 1974
Methods of test for determination
of strength properties of natural
building stones:
Compressive strength (first
revision)
Transverse strength (first revision)
Tensile strength (first revision)
Shear strength (first revision)
IS No, Title
1 1 22 : 1 974 Method of test for determination of
true specific gravity of natural
building stones (first revision)
1123 : 1975 Method of identification of natural
building stones (first revision)
1124 : 1974 Method of test for determination of
water absorption, apparent specific
gravity and porosity of natural
building stones (first revision)
1125 : 1974 Method of test for determination of
weathering of natural building
stones (first revision)
1126: 1974 Method of test for determination of
durability of natural building
stones (first revision)
1127 : 1970 Recommendations for dimensions
and workmanship of natural
building stones for masonry work
(first revision)
1128 : 1974 Specification for limestone (slab
and tiles) (first revision)
1129 : 1972 Recommendation for dressing
of natural building stones (first
revision)
1130 : 1969 Specification for marble (blocks,
slabs and tiles)
1706:1972 Method of determination of
resistance to wear by abrasion of
natural building stones (first
revision)
3316 : 1974 Specification for structural granite
(first revision)
3620: 1979 Specification for laterite stone
block for masonry (first revision)
3622 : 1977 Specification for sand stone (slabs
and tiles) (first revision)
4121 : 1967 Method of test for determination of
water transmission rate by capillary
action through natural building
stones
4 1 22 : 1 967 Method of test for surface softening
of natural building stones by
exposure to acidic atmospheres
4348 : 1973 Methods of test for determination
of permeability of natural building
stones (first revision)
5218 : 1969 Method of test for toughness of
natural building stones
5640 : 1970 Method of test for determining the
aggregate impact value of soft
coarse aggregates
34
NATIONAL BUILDING CODE OF INDL4
IS No. Title
6250 : 1981 Specification for roofing slate tiles
(first revision)
7779 Schedule for properties and
availability of stones for construction
purposes:
(Part 1/Sec 1) : Gujarat state, Section 1 Availability
1975 of stones
(Part 1/Sec 2) : Gujarat state, Section 2 Engineering
1975 properties of building stones
(Part 1/Sec 3) : Gujarat state, Section 3 Engineering
1975 properties of stone aggregates
(Part 2/Sec 1) : Maharashtra state, Section 1
1979 Availability of stones
(Part 2/Sec 2) : Maharashtra state, Section 2
1 979 Engineering properties of building
stones
(Part 2/Sec 3) : Maharashtra state, Section 3
1979 Engineering properties of stone
aggregates
(Part 3/Sec 2) : Tamil Nadu state, Section 2
1 990 Engineering properties of building
stones
(Part 3/Sec 3) : Tamil Nadu state, Section 3
1980 Engineering properties of stone
aggregates
(Part4/Sec 1 Karnataka state, Sections
to 3): 1996 (1 to 3)
(Part 5/Sec 1) : Andhra Pradesh, Section 1
1997 Availability of stones
(Part 5/Sec 2) : Andhra Pradesh, Section 2
1 997 Engineering properties of building
stones
(Part 5/Sec 3) : Andhra Pradesh, Section 3
1997 Engineering properties of stone
aggregates
9394 : 1979 Specification for stone lintels
14223 (Part 1) : Specification for polished building
1994 stones: Part 1 Granite
23. STRUCTURAL SECTIONS
a) Structural Shapes
811 : 1987 Specification for cold formed light
gauge structural steel sections
(revised)
1173 : 1978 Specification for hot rolled and slit
steel tee bars (second revision)
1852:1985 Specification for rolling and
cutting tolerances for hot rolled
steel products (fourth revision)
IS No. Title
1863 : 1979 Specification for hot rolled steel
bulb flats (first revision)
2314 : 1986 Specification for steel sheet piling
sections (first revision)
3443 : 1980 Specification for crane rail sections
(first revision)
3908 : 1986 Specification for aluminium equal
leg angles (first revision)
3909 : 1986 Specification for aluminium
unequal leg angles (first revision)
3921 : 1985 Specification for aluminium
channels (first revision)
3954 : 1991 Specification for hot rolled steel
channels sections for general
engineering purposes (first
revision)
3964 : 1980 Specification for light rails (first
revision)
5384: 1985 Specification for aluminium
I-beams (first revision)
6445 : 1985 Specification for aluminium tee
sections (first revision)
12779 : 1989 Rolling and cutting tolerances for
hot rolled parallel flange beam and
column sections
b) Dimensional Standards
808 : 1989 Dimensions for hot rolled steel
beam, column channel and angle
sections (third revision)
1730 : 1989 Dimensions for steel plates, sheets
strips and flats for general
engineering purposes (second
revision)
1732 : 1989 Dimensions for round and square
steel bars for structural and general
engineering purposes (second
revision)
2525 : 1982 Dimensions for wrought
alumiriium and aluminium alloy
wire (first revision)
2591 : 1982 Dimensions for hot rolled steel bars
for threaded components (second
revision)
2673 : 2002 Dimensions for wrought aluminium
and aluminium alloys, extruded
round tube (second revision)
2676 : 1981 Dimensions for wrought aluminium
and aluminium alloys, sheet and
strip (first revision)
PART 5 BUILDING MATERIALS
35
2678 : 1987
3577 : 1992
3965 : 1981
6477 : 1983
12778 : 1989
IS No. Title
2677 : 1979 Dimensions for wrought aluminium
and aluminium alloys, plates and
hot rolled sheets {first revision)
Dimensions and tolerances for
wrought aluminium and aluminium
alloys, drawn round tubes (second
revision)
Dimensions and tolerances for
wrought aluminium and aluminium
alloys rivet, bolt and screw stock
(first revision)
Dimensions for wrought aluminium
and aluminium alloys, bar, rod and
section (first revision)
Dimensions for wrought aluminium
and aluminium alloys, extruded
hollow sections
Dimensions for hot rolled steel
parallel flange beam and column
sections
24. THERMAL INSULATION MATERIALS
3144 : 1992 Methods of test for mineral wool
thermal insulation material (second
revision)
3346 : 1980 Methods for the determination of
thermal conductivity of thermal
insulation materials (two slab,
guarded hot-plate method) (first
revision)
3677 : 1985 Specification for unbonded rock
and slag wool for thermal insulation
(second revision)
4671 : 1984 Specification for expanded
polystyrene for thermal insulation
purposes (first revision)
5688 : 1982 Methods of test for preformed
block-type and pipe-covering type
thermal insulation (first revision)
5724: 1970 Methods of test for thermal
insulating cement
6598 : 1972 Specification for cellular concrete
for thermal insulation
7509 : 1993 Specification for thermal insulating
cement (first revision)
8154: 1 993 Specification for preformed calcium
silicate insulation for temperature
up to 650°C) (first revision)
8183 : 1993 Specification for bonded mineral
wool (first revision)
IS No.
9403 : 1980
9489 : 1980
9490 : 1980
9742 : 1993
9743 : 1990
9842 : 1994
11128: 1994
11129: 1984
11239
(Part 1) : 1985
(Part 2) : 1985
(Part 3) : 1985
(Part 4) : 1985
(Part 5) : 1985
(Part 6) : 1985
(Part 7) : 1985
(Part 8) : 1985
(Part 9) : 1985
(Part 10): 1985
(Part 11): 1985
(Part 12) : 1989
(Part 13): 1992
11307: 1985
11308: 1985
Title
Method of test for thermal
conductance and transmittance of
built up sections by means of
guarded hot box
Method of test for thermal
conductivity of materials by means
of heat flow meter
Method of determination for
thermal conductivity of insulation
materials (water calorimeter
method)
Specification for sprayed mineral
wool thermal insulation (first
revision)
Specification for thermal insulation
finishing cements (first revision)
Specification for preformed fibrous
pipe insulation (first revision)
Specification for spray applied
hydrated calcium silicate thermal
insulation
Method of test for tumbling
friability of preformed block-type
thermal insulation
Method of test for rigid cellular
thermal insulation materials:
Dimensions
Apparent density
Dimensional stability
Water vapour transmission rate
Volume percent of open and closed
cells
Heat distortion temperature
Coefficient of linear thermal
expansion at low temperatures
Flame height, time of burning and
loss of mass
Water absorption
Flexural strength
Compressive strength
Horizontal burning characteristics
Determination of flammability by
oxygen index
Specification for cellular glass
block and pipe thermal insulating
Specification for thermal insulating
castables (hydraulic setting) for
temperatures up to 1 250°C
36
NATIONAL BUILDING CODE OF INDIA
IS No. Title
12436 : 1988 Specification for preformed
rigid polyurethane (PUR) and
polyisocyanurate (Pir) foams for
thermal insulation
13204 : 1991 Specification for rigid phenolic
foams for thermal insulation
13286 : 1992 Methods of test for surface spread
of flame for thermal insulation
materials
25. THREADED FASTENERS AND RIVETS
207 : 1964 Specification for gate and shutter
hooks and eyes (revised)
451 : 1999 Specification for technical supply
conditions for wood screws (third
revision)
554 : 1999 Specification for pipe threads
where pressure-tide joints are made
on the threads — Dimensions,
tolerances and designation (fourth
revision)
723 : 1972 Specification for steel countersunk
head wire nails (second revision)
724 : 1964 Specification for mild steel and
brass cup, ruler and square hooks
and screw eyes (revised)
725 : 1961 Specification for copper wire nails
(revised)
730 : 1978 Specification for hook bolts for
corrugated sheet roofing (second
revision)
1120 : 1975 Specification for coach screws
(first revision)
1363 Specification for hexagon head
bolts, screws and nuts of product
grade C:
(Part 1 ) : 2002 Hexagon head bolts (size range M 5
to M64) (fourth revision)
(Part 2) : 2002 Hexagon head screws (size range
M5 to M64) (fourth revision)
(Part 3) : 2002 Part 3 Hexagon nuts (Size range
M5 to M64) (fourth revision)
1364 Specification for hexagon head
bolts, screws and nuts of product
Grades A and B:
(Part 1) : 2002 Hexagon head bolts (size range
Ml. 6 to M64) (fourth revision)
(Part 2) : 2002 Hexagon head screws (size range
Ml. 6 to M64) (fourth revision)
IS No.
(Part 3) :
2002
(Part 4) :
2003
(Part 5) :
2002
(Part 6) :
2002
365 : 1978
366 : 2002
367
(Part 1) :
2002
(Part 2) :
2002
(Part 3) :
2002
(Part 5) : 2002
(Part 6) : 1994
(Part 7) : 1980
(Part 8) : 2002
(Part 9/Sec 1) :
1993
(Part 9/Sec 2) :
1993
(Part 10) : 2002
(Part 11) :2002
(Part 12) : 1981
Title
Hexagon nuts (size range Ml. 6 to
M64) (fourth revision)
Hexagon thin nuts (chamfered)
(size range Ml. 6 to M64) (fourth
revision)
Hexagon thin nuts (unchamfered)
(size range M1.6 to M10) (fourth
revision)
Hexagon nuts, style 2
Specification for slotted countersunk
head screws (third revision)
Specification for slotted cheese
head screws (third revision)
Specification for technical supply
conditions for threaded steel
fasteners:
Introduction and general information
(third revision)
Product grades and tolerances
(third revision)
Mechanical properties and test
methods for bolts, screws and studs
with full loadability (fourth
revision)
Mechanical properties and test
methods for set screws and similar
threaded fasteners not under tensile
stresses (third revision)
Mechanical properties and test
methods for nuts with specified
proof loads (third revision)
Mechanical properties and test
methods for nuts without specified
proof loads (second revision)
Mechanical and performance
properties for prevailing torque
type steel hexagon nuts (third
revision)
Surface discontinuities, Section 1
Bolts, screws and studs for general
applications (third revision)
Surface discontinuities, Section 2
Bolts, screws and studs for special
applications (third revision)
Surface discontinuities on nuts
(third revision)
Electroplated coatings (third
revision)
Phosphate coatings on threaded
fasteners (second revision)
PART 5 BUILDING MATERIALS
37
IS No.
(Part 13): 1983
(Part 14/Sec 1) :
2002
(Part 14/Sec 2) :
2002
(Part 14/Sec 3) :
2002
(Part 16) : 2002
1929: 1982
2016 : 1967
2155 : 1982
2585 : 1968
2643 : 1999
2687 : 1991
2907 : 1998
2998 : 1982
3063 : 1994
3121 : 1981
3468 : 1991
3757 : 1985
Title
Hot dip galvanized coatings
on threaded fasteners (second
revision)
Mechanical properties of corrosion
resistance stainless steel fasteners,
Section 1 Bolts, screws and studs
(third revision)
Mechanical properties of corrosion
resistance stainless steel fasteners,
Section 2 Nuts (third revision)
Mechanical properties of corrosion
resistance stainless steel fasteners,
Section 3 Set screws and similar
fasteners not under tensile stress
(third revision)
Designation system and symbols
(third revision)
Specification for hot forged steel
rivets for hot closing (12 to 36 mm
diameter) (first revision)
Specification for plain washers
(first revision)
Specification for cold forged solid
steel rivets for hot closing (6 to
16 mm diameter) (first revision)
Specification for black square bolts
and nuts (dia range 6 to 39 mm)
and black square screws (dia range
6 to 24 mm) (first revision)
Dimensions, tolerances and
designation for pipe threads where
pressure-tight joints are not made
on the threads (second revision)
Specification for cap nuts (second
revision)
Specification for non-ferrous rivets
(first revision)
Specification for cold forged steel
rivets for cold closing (1 to 16 mm
diameter) (first revision)
Specification for fasteners single
coil rectangular section spring lock
washers (second revision)
Specification for rigging screws
and stretching screws (first
revision)
Specification for pipe nuts (second
revision)
Specification for high strength
structural bolts (second revision)
IS No.
4206:
1987
4762:
2002
5369:
1975
5372:
1975
5373:
1969
5374:
: 1975
5624:
: 1993
6113:
: 1970
6610:
: 1972
6623:
: 1985
6639
: 1972
6649
: 1985
6733 : 1972
6736 : 1972
6739 : 1972
6760 : 1972
8033: 1976
8412 : 1977
8822 : 1978
8869 : 1978
8911 : 1978
10102 : 1982
Title
Dimensions for nominal lengths,
and thread lengths for bolts, screws
and studs (first revision)
Specification for worm drive hose
clips for general purposes (second
revision)
General requirements for plain
washers and lock washers (first
revision)
Specification for taper washer for
channels (ISMC) (first revision)
Specification for square washers
for wood fastenings
Specification for taper washers for
L-beam (ISMB) (first revision)
Specification for foundation bolts
(first revision)
Specification for aluminium
fasteners for building purposes
Specification for heavy washers for
steel structures
Specification for high strength
structural nuts (first revision)
Specification for hexagon bolts for
steel structures
Specification for hardened and
tempered washers for high strength
structural bolts and nuts (first
revision)
Specification for wall and roofing
nails
Specification for slotted raised
countersunk head wood screws
Specification for slotted round
head wood screws
Specification for slotted
countersunk head wood screws
Specification for washers with
square hole for wood fastenings
Specification for slotted
countersunk head bolts for steel
structures
Specification for slotted mushroom
head roofing bolts
Specification for washers for
corrugated sheet roofing
Specification for slotted raised
countersunk head screws
Specification for technical supply
conditions for rivets
38
NATIONAL BUILDING CODE OF INDIA
IS No. Title
10238 : 2001 Specification for step bolts for steel
structures
12427 : 2001 Specification for transmission
tower bolts
26. UNIT WEIGHTS OF BUILDING MATERIALS
875 (Part 1) : Code of practice for design loads
1987 (other than earthquake) for
buildings and structures: Part 1
Dead loads — Unit weights of
building material and stored
materials (second revision)
27. WATERPROOFING AND DAMP-PROOFING
MATERIALS
IS No. Title
(Part 4) : 1993 Pressure head test
(Part 5) : 1993 Heat resistance test
(Part 6) : 1993 Water absorption test
(Part 7) : 1993 Determination of binder content
14695 : 1999 Specification for glass fibre base
coal tar pitch outer wrap
28. WELDING ELECTRODES AND WIRES
814 : 1991
1278 : 1972
1322: 1993
Specification for bitumen felts for
waterproofing and damp-proofing
(fourth revision)
1395
: 1982
1580 : 1991
Specification for bituminous
compound for waterproofing and
caulking purposes (first revision)
2879:
: 1998
3037 : 1986
Specification for bitumen mastic
for use in waterproofing of roofs
(first revision)
3613 :
: 1974
3384 : 1986
Specification for bitumen primer
for use in waterproofing and damp-
proofing (first revision)
4972:
: 1968
5871 : 1987
Specification for bitumen mastic
for tanking and damp-proofing
(first revision)
5206:
: 1983
7193 : 1994
12027 : 1987
Specification for glass fibre base
coal tar pitch and bitumen felts
(first revision)
Specification for silicone-based
water repellents
5511 :
1991
13435
Method of tests for acrylic based
waterproofing material:
5897:
1985
(Part 1): 1992
Determination of solid content
(Part 2) : 1992
Determination of coarse particle
(Part 3) : 1992
Determination of capillary water
take-up
5898:
1970
(Part 4) : 1992
(Part 5) : 1992
Determination of pH value
Determination of minimum film
forming temperature and white
point
6419:
1996
13826
Bitumen based felts — Method of
test:
6560:
1996
(Part 1) : 1993
Breaking strength test
(Part 2) : 1993
Pliability test
(Part 3) : 1993
Storage sticking test
Specification for covered
electrodes for manual metal arc
welding of carbon and carbon
manganese steel (fifth revision)
Specification for filler rods and
wires for gas welding (second
revision)
Specification for low and medium
alloy steel covered electrodes for
manual metal arc welding (third
revision)
Mild steel for metal arc welding
electrodes (third revision)
Acceptance tests for wire flux
combinations for submerged-arc
welding of structural steel (first
revision)
Specification for resistance spot-
welding electrodes
Covered electrodes for manual arc
welding of stainless steel and other
similar high alloy steels (first
revision)
Specification for covered
electrodes for manual metal arc
welding of cast iron (first revision)
Specification for aluminium and
aluminium alloy welding rods and
wires and magnesium alloy
welding rods (first revision)
Specification for copper and
copper alloy bare solid welding
rods and electrodes
Specification for welding rods and
bare electrodes for gas shielded arc
welding of structural steel (first
revision)
Specification for molybdenum and
chromium-molybdenum low alloy
steel welding rods and bare
electrodes for gas shielded arc
welding (first revision)
PART 5 BUILDING MATERIALS
39
Title
Specification for bare wire
electrodes for submerged-arc
welding of structural steels
Specification for bare wire electrodes
for electroslag welding of steels
Stainless steel for welding electrode
core wire
29. WIRE ROPES AND WIRE PRODUCTS
IS No.
7280:
1974
8363:
1976
10631
: 1983
278 : 1978
2140 : 1978
Specification for galvanized steel
barbed wire for fencing (third
revision)
Specification for stranded
galvanized steel wire for fencing
(first revision)
IS No, Title
2266 : 2002 Specification for steel wire ropes
for general engineering purposes
(fourth revision)
2365 : 1977 Specification for steel wire
suspension ropes for lifts , elevators
and hoists (first revision)
2721 : 2003 Specification for galvanized steel
wire chain link fences fabric
(second revision)
6594 : 1977 Specification for technical supply
conditions for wire ropes and
strands (first revision)
1 2776 : 2002 Specification for galvanized strand
for earthing (first revision)
40
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 1 Loads, Forces and Effects
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD ... 3
1 SCOPE ... 5
2 DEAD LOAD ... 5
3 IMPOSED LOAD ... 5
4 WIND LOAD ... 14
5 SEISMIC LOAD ... 53
6 SNOW LOAD ... 75
7 SPECIAL LOADS ... 81
8 LOAD COMBINATIONS ... 86
9 MULTI-HAZARD RISK IN VARIOUS DISTRICTS OF INDIA ... 86
ANNEX A ILLUSTRATIVE EXAMPLE SHOWING REDUCTION OF ... 88
UNIFORMLY DISTRIBUTED IMPOSED FLOOR LOADS IN
MULTI-STOREYED BUILDINGS FOR DESIGN OF COLUMNS
ANNEX B NOTATIONS ... 89
ANNEX C BASIC WIND SPEED A 10 m HEIGHT FOR SOME IMPORTANT ... 89
CITIES/TOWNS
ANNEX D CHANGES IN TERRAIN CATEGORIES ... 90
ANNEX E EFFECT OF A CLIFF OR ESCARPMENT ON THE EQUIVALENT ... 92
HEIGHT ABOVE GROUND (* 3 FACTOR)
ANNEX F WIND FORCE ON CIRCULAR SECTIONS ... 94
ANNEX G SYMBOLS ... 95
ANNEX H COMPREHENSIVE INTENSITY SCALE (MSK 64) ... 96
ANNEX J ZONE FACTORS FOR SOME IMPORTANT TOWNS ... 99
ANNEX K SHAPE COEFFICIENTS FOR MULTILEVEL ROOFS ... 100
ANNEX L VIBRATIONS IN BUILDINGS ... 101
ANNEX M SUMMARY OF DISTRICTS HAVING SUBSTANTIAL ... 102
MULTI-HAZARD RISK AREAS
LIST OF STANDARDS ... 103
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
This Section covers the various loads, forces and effects which are to be taken into account for structural design
of buildings. The various loads that are covered under this Section are dead load, imposed load, wind load,
seismic load, snow load, special loads and load combinations.
This Code was first published in 1970 and revised in 1983. Subsequently the first revision of this Section was
modified in 1987 through Amendment No. 2 to the 1983 version of the Code to bring this Section in line with the
latest revised loading code. Now, in view of the revision of the important Indian Standard on earthquake resistant
design of structure, that is IS 1893, a need to revise this Part was felt. This revision has therefore been prepared
to take into account this revised standard, IS 1893 (Part 1) : 2002 'Criteria for earthquake resistant design of
structures: Part 1 General provision and buildings (fifth revision)* and also incorporate latest information on
additional loads, forces and effects as also the details regarding multi-hazard risk in various districts of India.
The significant changes incorporated in this revision include:
a) The seismic zone map is revised with only four zones, instead of five. Erstwhile Zone I has been merged
in to Zone II. Hence, Zone I does not appear in the new zoning; only Zones II, III, IV and V do.
b) The values of seismic zone factors have been changed; these now reflect more realistic values of effective
peak ground acceleration considering Maximum Considered Earthquake (MCE) and service life of
structure in each seismic zone.
c) Response spectra are now specified for three types of founding strata, namely rock and hard soil, medium
soil and soft soil.
d) Empirical expression for estimating the fundamental natural period 7 of multi-storeyed buildings with
regular moment resisting frames has been revised.
e) This revision adopts the procedure of first calculating the actual force that may be experienced by the
structure during the probable maximum earthquake, if it were to remain elastic. Then, the concept of
response reduction due to ductile deformation or frictional energy dissipation in the cracks is brought in
this Section explicitly, by introducing the 'response reduction factor' in place of the earlier performance
factor.
f) A lower bound is specified for the design base shear of buildings, based on empirical estimate of the
fundamental natural period 7\
g) The soil-foundation system factor is dropped. Instead, a clause has been introduced to restrict the use of
foundations vulnerable to differential settlements in severe seismic zones.
h) Torsional eccentricity values have been revised upwards in view of serious damages observed in buildings
with irregular plans.
j) Modal combination rule in dynamic analysis of buildings has been revised.
k) Other clauses have been redrafted where necessary for more effective implementation.
m) A new clause on multi-hazard risk in various districts of India and a list of districts identified as multi-
hazard prone districts have been included.
n) Latest amendments issued to IS 875 have been incorporated.
p) A clause on vibration in buildings has been introduced for general guidance.
q) Reference has been included to the Indian Standards on landslide control and design of retaining walls,
formulated after the last revision of the Section.
The information contained in this Section is largely based on the following Indian Standards:
IS 1893 (Part 1) : 2002 Criteria for earthquake resistant design of structures: Part 1 General provisions
and buildings (fifth revision)
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS 3
IS 875 (Part 2) : 1987 Code of practice for design loads (other than earthquake) for buildings and
structures: Part 2 Imposed loads (second revision)
IS 875 (Part 3) : 1988 Code of practice for design loads (other than earthquake) for buildings and
structures: Part 3 Wind loads (second revision)
IS 875 (Part 4) : 1987 Code of practice for design loads (other than earthquake) for buildings and
structures: Part 4 Snow loads (second revision)
IS 875 (Part 5) : 1987 Code of practice for design loads (other than earthquake) for buildings and
structures: Part 5 Special loads and load combinations (second revision)
This Section has to be read together with Sections 2 to 7 of Part 6 'Structural Design'.
A reference to SP 64 (S&T) : 2001 'Explanatory Handbook on Indian Standard Code of practice for design
loads (other than earthquake) for buildings and structures: Part 3 Wind loads IS 875 (Part 3) : 1987' may be
useful. This publication gives detailed background information on the provisions for wind loads and also the use
of these provisions for arriving at the wind loads on buildings and structures while evaluating their structural
safety.
Reference may also be made to the Vulnerability Atlas of India, 1997 and Landslide Hazard Zonation Atlas of
India, 2003 Building Materials and Technology Promotion Council, Ministry of Urban Development and Poverty
Alleviation, Government of India. The vulnerability Atlas contains information pertaining to each State and
Union Territory of India, on (a) seismic hazard map, (b) cyclone, and wind map, (c) flood prone area map, and
(d) housing stock vulnerability table for each district indicating for each house type the level of risk to which it
could be subjected. The Atlas can be used to identify areas in each district of the country which are prone to high
risk from more than one hazard. The information will be useful in establishing the need of developing housing
designs to resist the combination of such hazards.
All standards, whether given herein above or cross-referred to in the main text of this Section, are subject to
revision. The parties to agreement based on this Section are encouraged to investigate the possibility of applying
the most recent editions of the standards.
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 1 Loads, Forces and Effects
1 SCOPE
1.1 This Section covers basic design loads to be
assumed in the design of buildings. The imposed loads,
wind loads, seismic loads, snow loads and other loads,
which are specified herein, are minimum working loads
which should be taken into consideration for purposes
of design.
1.2 This Section does not take into consideration loads
incidental to construction.
2 DEAD LOAD
2.1 Assessment of Dead Load
The dead load in a building shall comprise the weight
of all walls, partitions, floors and roofs, and shall include
the weights of all other permanent constructions in the
building and shall conform to good practice [6-1(1)].
3 IMPOSED LOAD
3.1 This clause covers imposed loads (live loads) to
be assumed in the design of buildings. The imposed
loads specified herein are minimum loads which should
be taken into consideration for the purpose of structural
safety of buildings.
NOTE — This Section does not cover detailed provisions for
loads incidental to construction and special cases of vibration,
such as moving machinery, heavy acceleration from cranes,
hoists and the like. Such loads shall be dealt with individually
in each case.
3.2 Terminology
3.2.1 For the purpose of imposed loads specified
herein, the following definitions shall apply:
3.2.1.1 Assembly Buildings — These shall include any
building or part of a building where groups of people
congregate or gather for amusement, recreation, social,
religious, patriotic, civil, travel and similar purposes;
for example, theatres, motion picture houses, assembly
halls, city halls, marriage halls, town halls, auditoria,
exhibition halls, museums, skating rinks, gymnasiums,
restaurants (also used as assembly halls), place of
worship, dance halls, club rooms, passenger stations
and terminals of air, surface and other public
transportation services, recreation piers and stadia, etc,
3.2.1.2 Business Buildings — These shall include any
building or part of a building, which is used for
transaction of business (other than that covered by
mercantile buildings); for keeping of accounts and
records for similar purposes; offices, banks,
professional establishments, courthouses, and libraries
shall be classified in this group so far as principal
function of these is transaction of public business and
the keeping of books and records.
3.2.1.3 Dwellings — These shall include any building
or part occupied by members of single/multi-family
units with independent cooking facilities. These shall
also include apartment houses (flats).
3.2.1.4 Educational Buildings — These shall include
any building used for school, college or day-care
purposes involving assembly for instruction, education
or recreation and which is not covered by assembly
buildings.
3.2.1.5 Imposed Load — The load assumed to be
produced by the intended use or occupancy of a
building including the weight of movable partitions,
distributed and concentrated loads, loads due to impact
and vibration, and dust loads but excluding wind,
seismic, snow and other loads due to temperature
changes, creep, shrinkage, differential settlement, etc.
3.2.1.6 Industrial Buildings — These shall include any
building or a part of a building or structure, in which
products or materials of various kinds and properties
are fabricated, assembled or processed like assembly
plants, power plants, refineries, gas plants, mills,
dairies, factories, workshops, etc.
3.2.1.7 Institutional Buildings — These shall include
any building or a part thereof, which is used for
purposes, such as, medical or other treatment in case
of persons suffering from physical and mental illness,
disease or infirmity; care of infants, convalescents or
aged persons and for penal or correctional detention
in which the liberty of the inmates is restricted.
Institutional buildings ordinarily provide sleeping
accommodation for the occupants. It includes hospitals,
sanitoria, custodial institutions or penal institutions like
jails, prisons and reformatories.
3.2.1.8 Occupancy or Use Group — The principal
occupancy for which a buijding or part of a building is
used or intended to be used; for the purpose of
classification of a building according to occupancy,
an occupancy shall be deemed to include subsidiary
occupancies which are contingent upon it. The
occupancy classification is given in the following
groups.
3.2.1.9 Office Buildings — The buildings primarily to
be used as an office or for office purposes; 'office
purposes' include the purpose of administration, clerical
work, handling money, telephone and telegraph operating,
and operating computers, calculating machines, 'clerical
work' includes writing, book-keeping, sorting papers,
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
typing, filing, duplicating, punching cards or tapes,
drawing of matter for publication and the editorial
preparation of matter for publication.
3.2.1.10 Mercantile Buildings — These shall include
any building or a part of a building which is used
as shops, stores, market for display and sale of
merchandize either wholesale or retail. Office, storage
and service and facilities incidental to the sale of
merchandize and located in the same building shall be
included under this group.
3.2.1.11 Residential Buildings — These shall include
any building in which sleeping accommodation is
provided for normal residential purposes with or
without cooking or dining or both facilities (except
buildings under institutional buildings). It includes one
or multi-family dwellings, apartment houses (flats),
lodging or rooming houses, restaurants, hostels,
dormitories and residential hotels.
3.2.1.12 Storage Buildings — These shall include any
building or part of a building used primarily for the
storage or sheltering of goods, wares or merchandize,
like warehouses, cold storages, freight depots, transity
sheds, store houses, garages, hangers, truck terminals,
grain elevators, barns and stables.
3.3 Imposed Loads on Floors Due to Use and
Occupancy
3.3.1 Imposed Loads
The imposed loads to be assumed in the design of
buildings shall be the greatest loads that probably will
be produced by the intended use or occupancy, but shall
not be less than the equivalent minimum loads specified
in Table 1 subject to any reductions permitted in 3.3.2.
Floors shall be investigated for both the uniformly
distributed load (UDL) and the corresponding
concentrated load specified in Table 1, and designed
for the most adverse effects but they shall not be
considered to act simultaneously. The concentrated
loads specified in Table 1 may be assumed to act over
an area of 0.3 m x 0.3 m. However, the concentrated
loads need not be considered where the floors are
capable of effective lateral distribution of this load.
All other structural elements shall be investigated for
the effects of uniformly distributed loads on the floors
specified in Table 1.
NOTES
1 Where, in Table 1 , no values are given for concentrated load,
it may be assumed that the tabulated distributed load is adequate
for design purposes.
2 The loads specified in Table 1 are equivalent uniformly
distributed loads on the plan area and provide for normal effects
of impact and acceleration. They do not take into consideration
special concentrated loads and other loads.
3 Where the use of an area or floor is not provided in Table 1,
the imposed load due to the use and occupancy of such an area
shall be determined from the analysis of loads resulting from:
a) weight of the probable assembly of persons;
b) weight of the probable accumulation of equipment and
furnishing;
c) weight of the probable storage materials; and
d) impact factor, if any.
4 While selecting a particular loading, the possible change in
use or occupancy of the building should be kept in view.
Designers should not necessarily select in every case the lower
loading appropriate to the first occupancy. In doing this they
might introduce considerable restrictions in the use of the
building at a later date, and thereby reduce its utility.
5 The loads specified herein, which are based on estimations,
may be considered as the characteristic loads for the purpose of
limit state method of design till such time statistical data are
established based on load surveys to be conducted in the country.
6 When an existing building is altered by an extension in
height or area, all existing structural parts affected by the
addition shall be strengthened where necessary and all new
structural parts shall be designed to meet the requirements for
building hereafter erected.
7 The loads specified in the section does not include loads
incidental to construction. Therefore, close supervision during
construction is essential to ensure that overloading of the building
due to loads by way of stacking of building materials or use of
equipment (for example, cranes and trucks) during construction
or loads which may be induced by floor to floor propping in
multi-storeyed construction, does not occur. However, if
construction loads were of short duration, permissible increase
in stresses in the case of working stress method or permissible
decrease in load factors in limit state method, as applicable to
relevant design codes, may be allowed for.
8 The loads in Table 1 are grouped together as applicable to
buildings having separate principal occupancy or use. For a
building with multiple occupancies, the loads appropriate to
the occupancy with comparable use shall be chosen from other
occupancies.
9 Regarding loading on lift machine rooms including storage
space used for repairing lift machines, designers should go by
the recommendations of lift manufacturers for the present.
Regarding loading due to fajse ceiling, the same should be
considered as imposed loads tin the roof/floor to which it is fixed.
Table 1 Imposed Floor Loads for Different Occupancies
{Clause 3.3.1)
Si
No.
(1)
Occupancy Classification
(2)
Uniformly Distributed
Load (UDL)
(3)
Concentrated Load
(4)
i) Residential Buildings
a) Dwelling houses:
1 ) All rooms and kitchens
2) Toilets and bathrooms
KN/m'
2.0
2.0
KN
1.8
NATIONAL BUILDING CODE OF INDIA
Table 1 — Continued
(1)
(2)
(3)
(4)
ii)
3) Corridors, passages, staircases including fire escapes
and store rooms
4) Balconies
b) Dwelling units planned and executed in accordance with
[6-1(2)] only:
1) Habitable rooms, kitchens, and toilets and bathrooms
2) Corridors, passages and staircases including fire escapes
3) Balconies
c) Hotels, hostels, boarding houses, lodging houses,
dormitories and residential clubs:
1) Living rooms, bed rooms and dormitories
2) Kitchen and laundries
3) Billiards room and public lounges
4) Store rooms
5) Dining rooms, cafeterias and restaurants
6) Office rooms
7) Rooms for indoor games
8) Baths and toilets
9) Corridors, passages staircases including fire escapes and
lobbies as per the floor services (excluding stores and
the like) but not less than
10) Balconies
d) Boiler rooms and plant roomsto be calculated but not less
than
e) Garages:
1) Garage floors (including parking area and repair
workshops for passenger cars and vehicles not
exceeding 2.5 tonnes gross weight, including access
ways and ramps — to be calculated but not less than
2) Garage floors for vehicles not exceeding 4.0 tonnes
gross weight (including access ways and ramps) — to be
calculated but not less than
Educational Buildings
a) Class rooms and lecture rooms (not used for assembly
purposes)
b) Dining rooms, cafeterias and restaurants
c) Offices, lounges and staff rooms
d) Dormitories
e) Projection rooms
f) Kitchens
g) Toilets and bathrooms
h) Storerooms
j) Libraries and archives:
1) Stack room/stack area
2) Reading rooms (without separate storage)
3) Reading rooms (with separate storage)
k) Boiler rooms and plant rooms — to be calculated but not
less than
m) Corridors, passages, lobbies, staircases including fire
escapes — as per the floor serviced (without accounting for
storage and projection rooms) but not less than
n) Balconies
3.0
3.0
1.5
1.5
.3.0
2.0
3.0
3.0
5.0
4.0
2.5
3.0
2.0
3.0
Same as rooms to which they
give access but with a
minimum of 4.0
5.0
2.5
5.0
3.0
4.5
1.5 per metre run
concentrated at the outer edge
1.4
1.4
1.5 per metre run
concentrated at the outer edge
1.8
4.5
2.7
4.5
2.7
2.7
1.8
4.5
1.5 per metre run
concentrated at the outer edge
6.7
9.0
9.0
2.7
3.0 l)
2.7
2.5
2.7
2.0
2.7
5.0
—
3.0
4.5
2.0
—
5.0
4.5
6.0 kN/m 2 for a
minimum
4.5
height of 2.2 m +
2.0 kN/m 2
per metre height beyond 2.2 m
4.0
4.5
3.0
4.5
4.0
4.5
4.0
Same as rooms to which they
give access but with a
minimum of 4.0
4.5
1.5 metre run concentrated at
the outer edge
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
Table 1 — Continued
(l)
(2)
(3)
(4)
iii) Institutional Buildings
a) Bed rooms, wards, dressing rooms, dormitories and lounges
b) Kitchens, laundries and laboratories
c) Dining rooms, cafeterias and restaurants
d) Toilets and bathrooms
e) X-ray rooms, operating rooms and general storage areas —
to be calculated but not less than
f) Office rooms and O.P.D. rooms
g) Corridors, passages, lobbies, staircases including fire
escapes — as per the floor serviced (without accounting for
storage and projection rooms) but not less than
h) Boiler rooms and plant rooms — to be calculated but not
less than
j) Balconies
iv) Assembly Building
a) Assembly areas:
1) With fixed seats 2)
2) Without fixed seats
b) Restaurants (subject to assembly), museums and art
galleries and gymnasia
c) Projection rooms
d) Stages
e) Office rooms, kitchens and laundries
f) Dressing rooms
g) Lounges and billiards rooms
h) Toilets and bathrooms
j) Corridors, passages and staircases including fire escapes
k) Balconies
m) Boiler rooms and plant rooms including weight of
machinery
n) Corridors, passages, subject to loads greater than from
crowds, such as wheeled vehicles, trolleys and the like
corridors, staircases and passages in grandstands
v) Business and Office Buildings (see also 3 2.1)
a) Rooms for general use with separate storage
b) Rooms without separate storage
c) Banking halls
d) Business computing machine rooms (with fixed computers
or similar equipment)
e) Records/files store rooms and storage space
f) Vaults and strong rooms — to be calculated but not less
than
g) Cafeterias and dinning rooms
h) Kitchens
j) Corridors, passages, lobbies, staircases including fire
escapes — as per the floor serviced (excluding stores) but
not less than
k) Bath and toilets rooms
m) Balconies
2.0
3.0
3.0 1}
2.0
3.0
2.5
4.0
5.0
Same as rooms to which they
give access but with a
minimum of 4.0
1.8
4.5
2.7
4.5
2.7
4.5
4.5
1.5 metre run concentrated at
the outer edge
4.0
_
5.0
3.6
4.0
4.5
5.0
5.0
4.5
3.0
4.5
2.0
1.8
2.0
2.7
2.0
—
4.0
4.5
Same as rooms to
give access but
minimum of 4.0
which they
with a
1.5 metre
the outer i
run concentrated at
edge
7.5
4.5
5.0
4.5
2.5
4.0
3.0
3.5
5.0
5.0
3.0 l >
3.0
4.0
2.0
n) Stationary stores
p) Boiler rooms and plant rooms — to be calculated but not
less than
q) Libraries
Same as rooms to which they
give access but with a
minimum of 4.0
4.0 for each metre of storage
height
5.0
S«?SlNo.(ii)
2.7
4.5
2.7
4.5
4.5
4.5
2.7
2.7
4.5
1.5 metre run concentrated at
the outer edge
9.0
6.7
NATIONAL BUILDING CODE OF INDIA
Table 1 — Concluded
(1)
(2)
(3)
(4)
vi)
vii)
Merchantile Buildings
a) Retail shops
b) Wholesale shops — to be calculated but not less than
c) Office rooms
d) Dining rooms, restaurants and cafeterias
e) Toilets
f) Kitchens and laundries
g) Boiler rooms and plant rooms — to be calculated but not
less than
h) Corridors, passages, staircases including fire escapes and
lobbies
j) Corridors, passages, staircases subject to loads greater than
from crowds, such as wheeled vehicles, trolleys and the like
k) Balconies
Industrial Buildings'^
a) Work areas without machinery/equipment
b) Work areas with machinery/equipment 3)
1) Light duty *1
2) Medium duty V To be calculated but not less than
3) Heavy duty J
c) Boiler rooms and plant rooms — to be calculated but not
less than
d) Cafeterias and dinning rooms
e) Corridors, passages, staircases including fire escapes
f) Corridors, passages, lobbies, staircases subject to machine
4.0
6.0
2.5
3.0»
2.0
3.0
5.0
' 4.0
5.0
Same as rooms to which they
give access but with a
minimum of 4.0
2.5
5.0
7.0
10.0
5.0
3.0 1}
4.0
5.0
loads and wheeled vehicles -
than
- to be calculated but not less
g) Kitchens 3.0
h) Toilets and bathrooms 2.0
viii) Storage Buildings 4 *
a) Storage rooms (other than cold storage) and warehouses — 2.4 kN/m 2 per metre of
to be calculated based on the bulk density of materials
stored but not less than
b) Cold storage — to be calculated but not less than
c) Corridors, passages, staircases including fire escapes — as
per the floor serviced but not less than
d) Corridors, passages subject to loads greater than from
crowds, such as wheeled vehicles, trolleys and the like
e) Boiler rooms and plant rooms
storage height with
minimum of 7.5 kN/m 2
5.0 kN/m 2 per metre
storage height with
minimum of 15 kN/m 2
4.0
5.0
7.5
of
a
3.6
4.5
2.7
2.7
4.5
6.7
4.5
4.5
1.5 metre run concentrated at
the outer edge
4.5
4.5
4.5
4.5
6.7
2.7
4.5
4.5
4.5
7.0
9.0
4.5
4.5
4.5
!) Where unrestricted assembly of persons is anticipated, the value of UDL should be increased to 4.0 kN/m 2
2) With fixed seats' implies that the removal of the seating and the use of the space for other purposes is improbable. The maximum
likely load in this case is, therefore, closely controlled. A .
3> The loading in industrial buildings (workshops and factories) varies considerably and so three loadings under the terms 'light*,
'medium' and 'heavy' are introduced in order to allow for more economical designs but the terms have no special meaning in
themselves other than the imposed load for which the relevant floor is designed. It is, however, important particularly in the case
of heavy weight loads, to assess the actual loads to ensure that they are not in excess of 10 kN/m 2 ; in case where they are in excess,
the design shall be based on the actual loadings.
4) For various mechanical handling equipment which are used to transport goods, as in warehouses, workshops, store rooms, etc, the
actual load coming from the use of such equipment shall be ascertained and design should cater to such loads.
3.3.1.1 Load application
The uniformly distributed loads specified in Table 1
shall be applied as static loads over the entire floor
area under consideration or a portion of the floor area
whichever arrangement produces critical effects on the
structural elements as provided in respective design
codes.
In the design of floors, the concentrated loads are
PART 6 STRUCTURAL DESIGN —SECTION 1 LOADS, FORCES AND EFFECTS 9
considered to be applied in the positions which produce
the maximum stresses and where deflection is the main
criterion in the positions which produce the maximum
deflections. Concentrated load, when used for the
calculation of bending and shear, are assumed to act at
a point. When used for the calculation of local effects,
such as, crushing or punching, they are assumed to act
over an actual area of application of 0.3 m x 0.3 m.
3.3.1.2 Loads due to light partitions
In office and other buildings, where actual loads due
to light partitions cannot be assessed at the time of
planning the floors and the supporting structural
members shall be designed to carry, in addition to other
loads, uniformly distributed loads per square metre of
not less than 33.33 percent of weight per metre run of
finished partitions, subject to a minimum of 1 kN/m 2 ,
provided total weight of partition walls per m 2 of the
wall area does not exceed 1.5 kN/m 2 and the total
weight per metre length is not greater than 4.0 kN.
3.3.2 Reduction in Imposed Loads on Floors
3.3.2.1 For members supporting floors
Except as provided for in 3,3.2.1 (a), the following
reductions in assumed total imposed loads on the floors
may be made in designing columns, load bearing walls,
piers, their supports and foundations.
Number of Floors
(Including the Roof)
to be Carried by
Member Under
Consideration
Reduction in Total
Distributed Imposed Load
on All Floors to be Carried
by the Member Under
Consideration Percent
(i)
i
(2)
2
3
4
5 to 10
Over 10
10
20
30
40
50
a) No reduction shall be made for any plant or
machinery which is specifically allowed for,
or for buildings for storage purposes,
warehouses and garages. However, for other
buildings, where the floor is designed for an
imposed floor load of 5.0 kN/m 2 or more, the
reductions shown in 3.3.2.1 may be taken
provided that the loading assumed is not less
than it would have been if all the floors
had been designed for 5.0 kN/m 2 with no
reductions.
NOTE — In case if the reduced load in the lower floor
is lesser than the reduced load in the upper floor, then
the reduced load of the upper floor will be adopted.
b) An example is given in Annex A illustrating
the reduction of imposed loads in a multi-
storeyed building in the design of column
members.
3.3.2.2 For beams in each floor level
Where a single span of beam, girder or truss supports
not less than 50 m 2 of floor at one general level, the
imposed floor load may be reduced in the design of
the beams, girders or trusses by 5 percent for each
50 m 2 area supported subject to a maximum reduction
of 25 percent. However, no reduction shall be made in
any of the following types of loads:
a) any superimposed moving load,
b) any actual load due to machinery or similar
concentrated loads,
c) the additional load in respect of partition
walls; and
d) any impact or vibration.
NOTE — The above reduction does not apply to beams,
girdes or trusses supporting roof loads.
3.3.3 Posting of Floor Capacities
Where a floor or part of a floor of a building has been
designed to sustain a uniformly distributed load
exceeding 3.0 kN/m 2 and in assembly, business
mercantile, industrial or storage buildings, a permanent
notice in the form shown below indicating the actual
uniformly distributed and/or concentrated loadings for
which the floor has been structurally designed shall be
posted in a conspicuous place in a position adjacent to
such floor or on such part of a floor.
DESIGNED IMPOSED FLOOR LOADING
Distributed kN/m 2
Concentrated kN
Label Indicating Designed Imposed
Floor Loading
NOTES
1 The lettering of such notice shall be embossed or cast suitably
on a tablet whose least dimension shall not be less than 0.25 m
and located not less than 1.5>m above floor level with lettering
of a minimum size of 25 mm.
2 If a concentrated load or a bulk load has to occupy a definite
position on the floor, the same could also be indicated in the
lable.
3.4 Imposed Loads on Roofs
3.4.1 Imposed Loads on Various Types of Roofs
On flat roofs, sloping roofs and curved roofs, the
imposed loads due to use and occupancy of the
buildings and the geometry of the types of roofs shall
be as given in Table 2.
10
NATIONAL BUILDING CODE OF INDIA
Table 2 Imposed Loads on Various Types of Roofs
{Clause 3.4.1)
SI
No.
Type of Roof
(1)
(2)
Imposed Load Measured on Flan Area
(3)
Minimum Imposed Load
Measured on Plan
(4)
Hat, sloping or curved roof with
slopes up to and including 10
degrees
a) Access provided
b) Access not provided except for
maintenance
1.5 kN/m 2
0.75 kN/m 2
ii) Sloping roof with slope greater than
10°
iii) Curved roof with slope of line
obtained by joining springing point
to the crown with the horizontal,
greater than 10°
3.75 kN uniformly distributed over
any span of one metre width of the
roof slab and 9 kN uniformly
distributed over the span of any beam
or truss or wall
1.9 kN uniformly distributed over any
span of one metre width of the roof
slab and 4.5 kN uniformly distributed
over the span of any beam or truss or
wall
Subject to a minimum of 0.4 kN/m 2
Subject to a minimum of 0.4 kN/m 2
For roof membrane sheets or purlins - 0.75 kN/m 2
less 0.02 kN/m 2 for every degree increase in slope
over 10°
(0.75 -0.52 a 2 ) kN/m 2
where
a=hll
h- height of the highest point of the structure
measured from its springing; and
I = chord width of the roof if singly curved and
shorter of the two sides if doubly curved.
Alternatively, where structural analysis can be
carried out for curved roofs of all slopes in a simple
manner applying the laws of statistics, the curved
roofs shall be divided into minimum 6 equal
segments and for each segment imposed load shall
be calculated appropriate to the slope of the chord
of each segment as given in (i) and (ii).
NOTES
1 The loads given above do not include loads due to snow, rain, dust collection, etc. The roof shall be designed for imposed loads
given above or for snow/rain load, whichever is greater.
2 For special types of roofs with highly permeable and absorbent material, the contingency of roof material increasing in weight due
to absorption of moisture shall be provided for.
3.4.1.1 Roofs of buildings used for promenade or
incidental to assembly purposes shall be designed for
the appropriate imposed floor loads given in Table 1
for the occupancy.
3.4.2 Concentrated Load on Roof Coverings
To provide for loads incidental to maintenance, unless
otherwise specified by the Engineer-in-Charge, all roof
coverings (other than glass or transparent sheets made
of fibre glass) shall be capable of carrying an incidental
load of 0.90 kN concentrated on an area of 12.5 cm 2 so
placed as to produce maximum stresses in the covering.
The intensity of the concentrated load may be reduced
with the approval of the Engineer-in-Charge, where it
is ensured that the roof coverings would not be traversed
without suitable aids. In any case, the roof coverings
shall be capable of carrying the loads in accordance
with 3.4.1, 3.4.3, 3.4.4 and wind load.
3.4.3 Loads Due to Rain
On surfaces whose positioning, shape and drainage
system are, such as, to make accumulation of rain water
possible, loads due to such accumulation of water and
the imposed loads for the roof as given in Table 2 shall
be considered separately and the more critical of the
two shall be adopted in the design.
3.4.4 Dust Loads
In areas prone to settlement of dust on roofs (example,
steel plants, cement plants), provision for dust load
equivalent to probable thickness of accumulation of
dust may be made.
3.4.5 Loads on Members Supporting Roof Coverings
Every member of the supporting structure which is
directly supporting the roof covering(s) shall be
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
11
designed to carrv the more severe of the following
loads except as provided in 3*4*5*1:
a) The load transmitted to the members from the
roof covering! s) in accordance with 3.4.1, 3.4.3
and 3.4.4; and
b) An incidental concentrated load of 0.90 kN
concentrated over a length of 12.5 cm placed
at the most favourable positions on the
member.
NOTE — Where it is ensured that the roofs would be
traversed only with the aid of planks and ladders capable
of distributing the loads on them to two or more
indicated in 3.4.5 (b) may be reduced to 0.5 kN with
the approval of the Engineer-in-Charge.
3.4.5.1 In case of sloping roois witn siope greater tnan
iv.;°, mcITiucTS Supporting tnc TOOi pUTunS, SUCii ES
* , i ™,. ~;-,4 — „ ~+^ m ,,,, u~ j~^;~«~j f^*. +,,,^
uus^cs, uca.ni:>, guucis, t;ic, may ut; ut^aigntu hji lwu-
* U i ••/! fi /\f tU/i i «-i»-w>in n/1 1/^n-ij-H /-i« v\n *«1 1 « s-\v ms^T inrt n 1-t date*
UlllUA UI Ult^ UlipW^^U IWtlU KJYl pUlllll KJl IWUllllg >3 1 lV^V^ U"> .
3.5 Imposed Horizontal Loads on Parapets and
Balustrades
3.5.1 Parapets, Parapet Walls and Balustrades
Parapets, parapet walls and balustrades, together with
the members which give them structural support, shall
be designed for the minimum loads given in Table 3.
These are expressed as horizontal forces acting at
handrail or coping level. These loads shall be
considered to act vertically also but not simultaneously
with the horizontal forces. The values given in Table 3
are minimum values and where values for actual
loadings are available, they shall be used instead.
Grandstands, stadia, assembly platforms, reviewing
stands and the like shall be designed to resist a
horizontal force applied to seats of 0.35 kN per linear
metre along the line of seats and 0.15 kN per linear
metre perpendicular to the line of the seats. These
loadings need not be applied simultaneously. Platforms
without seats shall be designed to resist a minimum
horizontal force of 0.25 kN/m 2 of plan area.
3.6 Loading Effects Due to Impact and Vibration
The crane loads to be considered under imposed loads
shall include the vertical loads, eccentricity effects
induced by vertical loads, impact factors, lateral and
longitudinal braking forces acting across and along the
crane rails respectively.
3.6.1 Impact Allowance for Lifts, Hoisis and Machinery
The imposed loads specified in 3.3.1 shall be assumed
to include adequate allowance for ordinary impact
conditions. However, for structures carrying loads
Table 3 Horizontal Loads on Parapets.
Parapet Walls and Balustrades
SI
Usage Area
Intensity of
No.
nonzoniai Luaa
kN/m Run
(1)
(2)
(3)
i) Lis
;ht aCCesS StairS, gangways and like
not more than 600 mm wide
ii) Light access stairs, gangways and like, 0.35
more than 600 mm wide; stairways,
landings, balconies and parapet walls
(private and part of dwellings)
iii) All Othef Stairways, landings and v. i ~>
balconies and all parapets and handrails
to roofs [except those subject to
overcrowding covered under (iv)J
iv) Parapets and balustrades in place of 2.25
aSSeinbiy, Such aS theatres, Cinemas,
churches, schools, places of
entertainment, sports and buildings and
buildings likely to be overcrowded
NOTE — In the case of guard parapets on a floor of multi-
storeyed car park or crash barriers provided in certain buildings
for fire escape, the vaiue of imposed horizontal load (together
with imrm^t lr*«(1^ mnv hp Hf»t"f»rminpH
which induce im n act or vibration, as far as n ossibIc^
calculations shall be made for increase in the imnosed
load due to impact or vibration. In the absence of
sufficient data for such calculation, the increase in the
imnosed loads shall be as follows:
Structures
a) For frames supporting lifts
and hoists
W\ Fnr fniinHatinn« fnntincrQ
and niers sunnortin** lifts and
hoisting apparatus
r*\ Pf/^ir ciir\r\/^it-tinrr etnir^tiir^c QnH
fruinHntirmQ fnr lioht
machinery, shaft or motor
units
r\\ PT/^ir ciir\r\rkrtinrr ctmrhirpc QnH
fminHntinnQ fnr rprinmrnrincr
marhinerv or nnwe.r units
Impact Allowance,
Percent,
Min
100
40
?n
sn
3.6.2 Concentrated Imposed Loads with Impact and
Vibration
Concentrated imposed loads with impact and vibration
which may be due to installed machinery snail be
considered and provided for in the design. The impact
factor snail not be less than 20 percent which is the
amount allowable for light machinery.
3.6.2.1 Provision shall also be made for carrying any
12
NATIONAL BUILDING CODE OF INDIA
concentrated equipment loads while the equipment is
being installed or moved for servicing and repairing.
3.6.3 Impact Allowance for Crane Girders
For crane gantry girders and supporting columns, the
impact allowances (given in informal table below) shall
be deemed to cover all forces set up by vibration, shock
from slipping of slings, kinetic action of acceleration,
and retardation and impact of wheel loads.
Forces specified in (c) and (d) shall be considered as
acting at the rail level and being appropriately
transmitted to the supporting system. Gantry girders
and their vertical supports shall be designed on the
assumption that either of the horizontal forces in
(c) and (d) may act at the same time as the vertical
load.
NOTE
cranes.
See [6-1(3)] for classification (Class I to IV) of
b)
c)
d)
Impact Allowance for Crane Girders
(Clause 3.63)
Type of Load
a) Vertical loads for electric overhead
cranes
Vertical loads for hand operated cranes
Horizontal forces transverse to rails:
1) For electric overhead cranes with
trolley having rigid mast for
suspension of lifted weight (such as,
soaker crane, stripper crane, etc)
2) For all other electric overhead
cranes and hand operated cranes
Horizontal traction forces along the
rails for overhead cranes, either
electrically operated or hand operated
Additional Load
25 percent of maximum static loads for crane girders for all
class of cranes
25 percent for columns supporting Class HI and Class IV
cranes.
10 percent for columns supporting Class I and Class II cranes.
No additional load for design of foundations.
10 percent of maximum wheel loads for crane girders only
10 percent of weight of crab and the weight lifted by the
cranes, acting on any one crane track rail, acting in either
direction and equally distributed amongst all the wheels on
one side of rail track
For frame analysis, this force, calculated as above, shall be
applied on one side of the frame at a time in either direction.
5 percent of weight of crab and the weight lifted by the
cranes, acting on any one crane track rail, acting in either
direction and equally distributed amongst the wheels on one
side of rail track
For the frame analysis, the force, calculated as above, shall be
applied on one side of the frame at a time in either direction.
5 percent of all static wheel loads
3.6.3.1 Overloading factors in crane supporting
structures
For all ladle cranes and charging cranes where there
is possibility of overloading from production
considerations, an overloading factor of 10 percent of
the maximum wheel loading shall be taken.
3.6.4 Crane Load Combinations
In the absence of any specific indications, the load
combinations shall be as indicated below.
3.6.4.1 Vertical loads
In an aisle, where more than one crane is in operation
or has provision for more than one crane in future, the
following load combinations shall be taken for vertical
loading:
a) Two adjacent cranes working in tandem with
full load and with overloading according to
3.6.3.1; and
b) For long span gantijes, where more than one
crane can come in the span, the girder shall
be designed for one crane fully loaded with
overloading according to 3.63.1 plus as many
loaded cranes as can be accommodated on
the span but without taking into account
overloading according to 3.6,3 (a) to give the
maximum effect.
3.6.4.2 Lateral surge
For design of columns and foundations, supporting
crane girders, the following crane combinations shall
be considered:
PART 6 STRUCTURAL DESIGN— SECTION 1 LOADS, FORCES AND EFFECTS
13
a) For Single Bay Frames — Effect of one crane
in the bay giving the worst effect shall be
considered for calculation of surge force; and
b) For Multi-Bay Frames — Effect of two cranes
working, one each in any of two bays in the
cross-section to give the worst effect shall be
considered for calculation of surge force.
3.6.4.3 Tractive force
a) Where one crane is in operation with no
provision for future crane, tractive force from
only one crane shall be taken.
b) Where more than one crane is in operation or
there is provision for future crane, tractive
force from two cranes giving maximum effect
shall be considered.
NOTE — Lateral surge force and longitudinal tractive
force acting across and along the crane rail respectively
shall not be assumed to act simultaneously. However,
if there is only one crane in the bay, the lateral and
longitudinal forces may act together simultaneously
with vertical loads.
4 WIND LOAD
4,1 General
This clause gives wind forces and their effects (static
and dynamic) that should be taken into account when
designing buildings, structures and components
thereof.
NOTES
1 It is believed that ultimately wind load estimation will be
made by taking into account the random variation of wind
speed with time, but available theoretical methods have not
matured sufficiently at present for use in the Section. For
this reason, equivalent static load estimation which implies a
steady wind speed, which has proved to be satisfactory for
normal, short and heavy structures, is given in 4.5 and 4.6.
However, a beginning has been made to take account of the
random nature of the wind speed by requiring that the along-
wind or drag load on structures which are prone to wind
induced oscillations, be also determined by the gust factor
method {see 4.8) and the more severe of the two estimates be
taken for design.
A large majority of structures met within practice do not,
however, suffer wind induced oscillations and generally do
not require to be examined for the dynamic effects of wind
including use of gust factor method. Nevertheless, there are
various types of structures or their components, such as some
tall buildings, etc, which require investigation of wind incjuced
oscillations. In identifying and analyzing such structures 4.6
shall be followed.
2 In the case of tall structures with un symmetrical geometry,
the designs may have to be checked for torsional effects due
to wind pressure.
4.1.1 Wind is air in motion relative to the surface of
the earth. The primary cause of wind is traced to earth' s
rotation and differences in terrestrial radiation. The
radiation effects are primarily responsible for
convection either upwards or downwards. The wind
generally blows horizontal to the ground at high wind
speeds. Since vertical components of atmospheric
motion are relatively small, the term 'wind' denotes
almost exclusively the horizontal wind, vertical winds
are always identified as such. The wind speeds are
assessed with the aid of anemometers or anemographs
which are installed at meteorological observatories
at heights generally varying from 10 to 30 m above
ground.
4.1.2 Very strong wind speeds (greater than 80 km/h)
are generally associated with cyclonic storms,
thunderstorms, dust storms or vigorous monsoons. A
feature of the cyclonic storms over the Indian area is
that they rapidly weaken after crossing the coasts and
move as depressions/lows inland. The influence of a
severe storm after striking the coast does not, in general,
exceed about 60 km, though sometimes, it may extend
even up to 120 km. Very short duration hurricanes of
very high wind speeds called Kal Baisaki or Norwesters
occur fairly frequently during summer months over
North-Eastern India.
4.1.3 The wind speeds recorded at any locality are
extremely variable and, in addition to steady wind at
any time, there are effects of gusts which may last for
a few seconds. These gusts cause increase in air
pressure but their effect on the stability of the building
may not be so important; often, gusts affect only part
of the building and the increased local pressures may
be more than balanced by a momentary reduction in
the pressure elsewhere. Because of the inertia of the
building, short period gusts may not cause any
appreciable increase in stress in the main components
of the building, although the walls, roof sheeting and
individual cladding units (glass panels) and their
supporting members, such as purlins, sheeting rails and
glazing bars may be more seriously affected. Gusts
can also be extremely important for the design of
structures with high slenderness ratios.
4.1.4 The liability of a building to high wind pressures
depends not only upon the geographical location and
proximity of other obstructions to air flow but also upon
the characteristics of the structure itself.
4.1.5 The effect of wind on the structure as a whole is
determined by the combined action of external and
internal pressures acting upon it. In all cases, the
calculated wind loads act normal to the surface to which
they apply.
4.1.6 Buildings shall also be designed with due
attention to the effects of wind on the comfort of people
inside and outside the buildings.
4.1.7 The stability calculations of the building as a
whole shall be done considering the combined effect,
as well as separate effects of imposed loads and wind
14
NATIONAL BUILDING CODE OF INDIA
loads on vertical surfaces, roofs and other parts of the
building above the general roof level.
4.2 Notations
The notations to be followed, unless otherwise
specified in relevant clauses under wind loads, are
given in Annex B.
4.3 Terminology
4.3.1 For the purpose of wind loads, the following
definitions shall apply.
4.3.1.1 Angle of attack — Angle between the direction
of wind and a reference axis of the structure.
4.3.1.2 Breadth — Breadth means horizontal
dimension of the building measured normal to the
direction of wind.
4.3.1.3 Depth — Depth means the horizontal
dimension of the building measured in the direction
of the wind.
NOTE — Breadth and depth are dimensions measured in
relation to the direction of the wind, whereas length and width
are dimensions related to the plan,
4.3.1.4 Developed height
Developed height is the height of upward penetration
of the velocity profile in a new terrain. At large, fetch
lengths, such penetration reaches the gradient height
above which the wind speed may be taken to be
constant. At lesser-fetch lengths, a velocity profile of
a smaller height but similar to that of the fully
developed profile of that terrain category has to be
taken, with the additional provision that the velocity
at the top of this shorter profile equals that of the
unpenetrated earlier velocity profile at that height.
4.3.1.5 Effective frontal area
The projected area of the structure normal to the
direction of the wind.
4.3.1.6 Element surface area
The area of surface over which the pressure coefficient
is taken to be constant.
4.3.1.7 Force coefficient
A non-dimensional coefficient such that the total wind
force on a body is the product of the force coefficient,
the dynamic pressure of the incident design wind
speed and the reference area over which the force is
required.
NOTE — When the force is in the direction of the incident
wind, the non-dimensional coefficient will be called as drag
coefficient. When the force is perpendicular to the direction
of incident wind the non-dimensional coefficient will be called
as 'lift coefficient'.
4.3.1.8 Ground roughness
The nature of the earth's surface as influenced by small
scale obstructions such as trees and buildings (as
distinct from topography) is called ground roughness.
4.3.1.9 Gust
A positive or negative departure of wind speed from
its mean value, lasting for not more than say 2 min
over a specified interval of time.
4.3.1.10 Peak gust
Peak gust or peak gust speed is the wind speed
associated with the maximum amplitude.
4.3.1.11 Fetch length
Fetch length is the distance measured along the wind
from a boundary at which a change in the type of terrain
occurs. When the changes in terrain types are
encountered (such as the boundary of a town or city,
forest, etc), the wind profile changes in character but
such changes are gradual and start at ground level,
spreading or penetrating upwards with increasing fetch
length.
4.3.1.12 Gradient height
Gradient height is the height above the mean ground
level at which the gradient wind blows as a result of
balance among pressure gradient force, coriolis force
and centrifugal force. For the purpose of this Section,
the gradient height is taken as the height above the
mean ground level above which the variation of wind
speed with height need not be considered.
4.3.1.13 Mean ground level
The mean ground level is the average horizontal plane
of the area enclosed by the boundaries of the structure.
4.3.1.14 Pressure coefficient
Pressure coefficient is the ratio of the difference
between the pressure acting at a point on a surface and
the static pressure of the incident wind to the design
wind pressure, where the static and design wind
pressure are determined at the height of the point
considered after taking into account the geographical
location, terrain conditions and shielding effect. The
pressure coefficient is also equal to [1-(V7V Z ) 2 ], where
V is the actual wind speed at any point on the structure
at a height corresponding to that of V z .
NOTE — Positive sign of the pressure coefficient indicates
pressure acting towards the surface and negative sign indicates
pressure acting away from the surface.
4.3.1.15 Return period
Return period is the number of years, the reciprocal of
which gives the probability of extreme wind exceeding
a given wind speed in any one year.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
15
4.3.1.16 Shielding effect
Shielding effect or shielding refers to the condition
where wind has to pass along some structure(s) or
structural element(s) located on the upstream wind side,
before meeting the structure or structural element under
consideration. A factor called 'shielding factor' is used
to account for such effects in estimating the force on
the shielded structures.
4.3.1.17 Suction
Suctions means pressure less than the atmospheric
(static) pressure and is taken to act away from the
surface.
4.3.1.18 Solidity ratio
Solidity ratio is equal to the effective area (projected
area of all the individual elements) of a frame normal
to the wind direction divided by the area enclosed by
the boundary of the frame normal to the wind direction.
NOTE — Solidity ratio is to be calculated for individual frames.
4.3.1.19 Terrain category
Terrain category means the characteristics of the
surface irregularities of an area which arise from natural
or constructed features. The categories are numbered
in increasing order of roughness.
4.3.1.20 Velocity profile
The variation of the horizontal component of the
atmospheric wind speed at different heights above the
mean ground level is termed as velocity profile.
4.3.1.21 Topography
The nature of the earth's surface as influenced by the
hill and valley configurations.
4.4 Wind Speed and Pressure
4.4.1 Nature of Wind in Atmosphere
In general, wind speed in the atmospheric boundary
layer increases with height from zero at ground level
to a maximum at a height called the gradient height.
There is usually a slight change in direction (Ekman
effect) but this is ignored in the Section. The variation
with height depends primarily on the terrain conditions.
However, the wind speed at any height never remains
constant and it has been found convenient to resolve
its instantaneous magnitude into an average or mean
value and a fluctuating component around this average
value. The average value depends on the averaging
time employed in analyzing the meteorological data
and this averaging time varies from a few seconds to
several minutes. The magnitude of the fluctuating
component of the wind speed, which is called as gust,
depends on the averaging time. In general, smaller the
averaging interval, greater is the magnitude of the gust
speed.
4.4.2 Basic Wind Speed
Figure 1 gives basic wind speed map of India, as
applicable to 10 m height above mean ground level
for 10 m height above mean ground level for different
zones of the country. Basic wind speed is based on
peak gust velocity averaged over a short time interval
of about 3 s and corresponds to mean heights above
ground level in an open terrain (Category 2). Basic
wind speeds presented in Fig. 1 have been worked out
for a 50 year return period. Basic wind speed for some
important cities/towns is also given in Annex C.
4A3 Design Wind Speed (V z )
The basic wind speed ( V b ) for any site shall be obtained
from Fig. 1 and shall be modified to include the
following effects to get V z , design wind speed at any
height for the chosen structure.
a) risk level;
b) terrain roughness, height and size of structure;
and
c) local topography.
It can be mathematically expressed as follows:
where
V = design of wind speed at any height z in m/s;
V h = basic wind speed in m/s (Fig. 1);
fcj = probability factor (risk coefficient) (4.4.3.1);
k 2 = terrain, height and structure size factor
(4.4.3.2); and
k 3 = topography factor (4.4.3.3)
NOTE — Design wind speed up to 10 m height from mean
ground level shall be considered constant.
4.4.3.1 Risk coefficient (k { )
Figure 1 gives basic wind speeds for terrain Category 2
as applicable at 10 m above ground level based on
50 year mean return period. The suggested life period
to be assumed in design and the corresponding k l
factors for different classes of structure for the purpose
of design is given in Table 4. In the design of all
buildings and structures, a regional basic wind speed
having a mean return period of 50 years shall be used
except as specified in the note of Table 4.
4.4.3.2 Terrain, height and structure size factor (k 2 )
a) Terrain — Selection of terrain categories shall
be made with due regard to the effect of the
obstruction which constitute the ground surface
roughness. The terrain category used in the
16
NATIONAL BUILDING CODE OF INDIA
Based upon Survey of India Outline Map printed In 1993
The territorial waters of India extend into nwseatad distance of twelve nautical miles measured from Ihe appropriate base line
The boundary of Meghatoya shown on this map is as interpreted from the North-Eastam Areas (Recrcjanisetton) Act. 11171, hut has yet to be vertfted
Responsibility tor correctness of internal details shown on the map rests with the publisher
The state bour«darlG6 between Uttaranchal & Uttar Pradesh, B<har & Jherkhand and Chhattegarh & Madhys Pradesh have not been verified by Governments concerned.
©Govemmert of India Copyright, 2005
Fig 1 Basic Wind Speed in m/s (Based on 50- Years Return Period)
Table 4 Risk Coefficients for Different Classes of Structures in Different Wind Speed Zones
(Clause 4.4.3.1)
Class of Structure
Mean Probable
Design Life of
Structure in Years
(2)
ki Factor for Basic Wind Speed
(m/s) of
(1)
*■ —
33
(3)
39 44 47 50
(4) (5) (6) (7)
55
(8)
All general buildings and structures
Temporary sheds, structures such as
those
50
5
1.0
0.82
1.0 1.0 1.0 1.0
0.76 0.73 0.71 0.70
1.0
0.67
used during construction operations (for
example, formwork and falsework),
structures during construction stages and
boundary walls
Buildings and structures presenting a low
degree of hazard to life and property in the
event of failure, such as isolated towers in
wooded areas, farm buildings, other than
residential buildings
Important buildings and structures, such as
hospitals, communications buildings/towers
and power plant structures
25
100
0.94 0.92 0.91 0.90 0.90 0.89
1.05 1.06 1.07 1.07 L08 1.08
*,=-
-* N * N
A-B
ln[-\-ln{\ -/» N )}
N
A + 4B
where
N = mean probable design life of structure in years;
P K = risk level in N consecutive years (probability that the design wind speed is exceeded at least once in N successive
years), nominal value = 0.63;
extreme wind speed for given values of N and /> N ; and
"so 63 = extreme wind speed for N = 50 years and P N = 0.63
N' N
A and B are coefficients having the following values for different basic wind speed zones:
Zone A B
33 m/s 83.2 9.2
39 m/s 84.2 14.0
44 m/s 88.0 18.0
47 m/s 88.0 20.5
50 m/s 88.8 22.8
55 m/s 90.8 27.3
NOTE — The factor h l is based on statistical concepts which take account of the degree of reliability required and period of time
in years during which there will be exposure to wind, that is, life of the structure. Whatever wind speed is adopted for design
purposes, there is always a probability (however small) that it may be exceeded in a storm of exceptional violence; the greater
the period of years over which there will be exposure to wind, the greater is the probability. Higher return periods ranging from
100 to 1 000 years (implying lower risk level) in association with greater periods of exposure may have to be selected for
exceptionally important structures, such as nuclear power reactors and satellite communication towers. Equation given above
may be used in such cases to estimate k x factors for different periods of exposure and chosen probability of exceedence (risk
level). The probability level of 0.63 is normally considered sufficient for design of buildings and structures against wind effects
and the values of k } corresponding to this risk level are given in Table 4.
design of a structure may vary depending on
the direction of wind under consideration.
Wherever sufficient meteorological
information is available about the nature of
wind direction, the orientation of any building
or structure may be suitably planned.
Terrian, in which a specific structure stands,
shall be assessed as being one of the following
terrain categories:
Category 1 — Exposed open terrain with few
or no obstructions and in which the average
height of any objects surrounding the structure
is less than L5 m.
NOTE — This category includes open sea-coasts and
flat treeless plains.
Category 2 — Open terrain with well scattered
obstructions having heights generally between
1.5 and 10 m.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
19
b)
NOTE — This is the criterion for measurement of
regional basic wind speeds and includes airfields, open
parklands and undeveloped sparsely built-up outskirts
of towns and suburbs. Open land adjacent to sea coast
may also be classified as category 2 due to roughness
of large sea waves at high winds.
Category 3 — Terrain with numerous closely
spaced obstruction having the size of
building-structures up to 10 m in height with
or without a few isolated tall structures.
NOTES
1 This category includes well wooded areas and shrubs,
towns and industrial areas fully or partially developed.
2 It is likely that the next higher category than this
will not exist in most design situations and that selection
of a more severe category will be deliberate.
3 Particular attention must be given to the performance
of the obstructions in areas affected by fully developed
tropical cyclones. Vegetation, which is likely to be
blown down or defoliated, cannot be relied upon to
maintain Category 3 conditions. Where such situation
may exist, either an intermediate category with velocity
multipliers midway between the values for Categories
2 and 3 given in Table 5 or Category 2 should be
selected having due regard to local conditions.
Category 4 — Terrain with numerous large
high closely spaced obstructions.
NOTE — This category includes large city centres,
generally with obstructions above 25 m and well
developed industrial complexes.
Variation of Wind Speed with Height for
Different Sizes of Structure in Different
Terrains (k 2 Factor) — Table 5 gives
c)
multiplying factors (k 2 ) by which the basic
wind speed given in Fig. 1 shall be multiplied
to obtain the wind speed at different heights,
in each terrain category for different sizes of
buildings/structures.
The buildings/structures are classified into the
following three different classes depending
upon their size:
Class A — Buildings and/or their components,
such as cladding, glazing, roofing etc, having
maximum dimension (greatest horizontal or
vertical dimension) less than 20 m.
Class B — Buildings and/or their components,
such as cladding, glazing, roofing etc,
having maximum dimension (greatest
horizontal or vertical dimension) between
20 m and 50 m.
Class C — Buildings and/or their components,
such as cladding, glazing, roofing etc, having
maximum dimension (greatest horizontal or
vertical dimension) greater than 50 m.
Terrain Categories in Relation to the
Direction of Wind — The terrain category
used in the design of a building may
vary depending on the direction of wind
under consideration. Where sufficient
meteorological information is available, the
basic wind speed may be varied for specific
wind direction.
Table 5 k 2 Factors to Obtain Design Wind Speed Variation with Height in Different
Terrains for Different Classes of Building Structures
[Clause 4.4.3.2 (b)]
Height
Terrain
Terrain
Terrain
Terrain
(m)
Category 1 Class
Category 2 Class
Category 3 Class
Category 4 Class
jk.
,-*-
>t
,j^
A
B
C
^— ■■■"—'■»
A
B
C
A
B
C
A
B
C
10
1.05
1.03
0.99
1.00
0.98
0.93
0.91
0.88
0.82
0.80
0.76
0.67
15
1.09
1.07
1.03
1.05
1.02
0.97
0.97
0.94
0.87
0.80
0.76
0.67
20
1.12
1.10
1.06
1.07
1.05
1.00
1.01
0.98
0,91
0.80
0.76
0.67
30
1.15
1.13
1.09
1.12
1.10
1.04
1.06
1.03
6.96
0.97
0.93
0.83
50
1.20
1.18
1.14
1.17
1.15
1.10
1.12
1.09
1.02
1.10
1.05
0.95
100
1.26
1.24
1.20
1.24
1.22
1.17
1.20
1.17
uo
1.20
1.15
1.05
150
1.30
1.28
1.24
1.28
1.25
1.21
1.24
1.21
iJ
1.24
1.20
1.10
200
1.32
1.30
1.26
1.30
1.28
1.24
1,27
1.24
1.18
1.27
1.22
1.13
250
1.34
1.32
1.28
1.32
1.31
1.26
1.29
1.26
1.20
1.28
1.24
1.16
300
1.35
1.34
1.30
1.34
1.32
1.28
1.31
1.28
1.22
1.30
1.26
1.17
350
1.37
1.35
1.31
1.36
1.34
1.29
1.32
1.30
1.24
1.31
1.27
1.19
400
1.38
1.36
1.32
1.37
1.35
1.30
1.34
1.31
1.25
1.32
1.28
1.20
450
1.39
1.37
1.33
1.38
1.36
1.31
1.35
1.32
1.26
1.33
1.29
1.21
500
1.40
1.38
1.34
1.39
1.37
1.32
1.36
1.33
1.28
1.34
1.30
1.22
NOTES
1 See 4.43.2 (b) for definitions of Class A, Class B and Class C structures.
2 Intermediate values may be obtained by linear interpolation, if desired. It is permissible to assume constant wind speed between two
heights for simplicity.
20
NATIONAL BUILDING CODE OF INDIA
d) Changes in Terrain Categories — The velocity
profile for a given terrain category does not
develop to full height immediately with the
commencement of that terrain category, but
develops gradually to height (h x ), which
increases with the fetch or upwind distance (x)
1) Fetch and Developed Height
Relationship — The relation beween the
developed height (h x ) and the fetch (x)
for wind-flow over each of the four
terrain categories may be taken as given
in Table 6.
2) For buildings of heights greater than the
developed height (h x ) in Table 6, the
velocity profile may be determined in
accordance with the following:
i) The less or least terrain; or
ii) The method described in Annex D.
Table 6 Fetch and Developed Height
Relationship
[Clause 4.4.3.2(b)]
Developed Height, fc x in m
Fetch
Terrain
Terrain
Terrain
Terrain
(x)km
Category 1
Category 2
Category 3
Category 4
(1)
(2)
(3)
(4)
(5)
0.2
0.5
1
2
5
10
20
50
12
20
25
35
60
80
120
180
20
30
45
65
100
140
200
300
35
35
80
110
170
250
350
400
60
95
130
190
300
450
500
500
4.4.3.3 Topography (k v factor)
The basic wind speed V b given in Fig. 1 takes account
of the general level of the site above sea level. This
does not allow for local topographic features, such as
hills, valleys, cliffs, escarpments or ridges, which can
significantly affect wind speed in their vicinity. The
effect of topography is to accelerate wind near the
summits of hills or crests of cliffs, escarpments or
ridges and decelerate the wind in valleys or near the
foot of cliffs, steep escarpments or ridges.
The effect of topography will be significant at a site
when the upwind slope is greater than about 3°, and
below that the value of k 3 may be taken to be equal
to 1 .0. The value of k 3 is confined in the range of 1 .0
to 1.36 for slopes greater than 3°. A method of
evaluating the value of k 3 for slope greater than 3° is
given in Annex E. It may be noted that the value of k 3
varies with height above ground level with a maximum
near the ground, and reducing to 1.0 at higher levels.
4.4.4 Design Wind Pressure
The design wind pressure at any height above mean
ground level shall be obtained by the following
relationship between wind pressure and wind
velocity:
p=0.6V>
where
p z ~ design wind pressure in N/m 2 at height Z,
and
V z = design wind velocity in m/s at height Z.
NOTE — The coefficient 0.6 (in SI units) in the above
formula depends on a number of factors, and mainly on the
atmospheric pressure and air temperature. The value chosen
corresponds to the average appropriate Indian atmospheric
conditions.
4.4.5 Offshore Wind Velocity
Cyclonic storms form far way from the sea coast and
gradually reduce in speed as they approach the sea
coast. Cyclonic storms generally extend up to about
60 km inland after striking the coast. Their effect on
land is already reflected in basic wind speeds specified
in Fig. 1 . The influence of wind speed off the coast up
to a distance of about 200 km may be taken as
1.15 times the value on the nearest coast in the absence
of any definite wind data.
4.5 Wind Pressure and Forces on Buildings/
Structure
4.5.1 General
The wind load on a building shall be calculated for:
a) the building as a whole;
b) individual structural elements as roofs and
walls; and
c) individual cladding units including glazing
and their fixings.
4.5.2 Pressure Coefficients
The pressure coefficients are always given for a
particular surface or part of the surface of a building.
The wind load acting normjd to a surface is obtained
by multiplying the area of that surface or its appropriate
portion by the pressure coefficient (C _); and the design
wind pressure at the height of the surface from the
ground. The average values of these pressure
coefficients for some building shapes are given
in 4.5.2.2 and 4.5.2.3.
Average values of pressure coefficients are given for
critical wind directions in one or more quadrants. In
order to determine the maximum wind load on the
building, the total load should be calculated for each
of the critical directions shown from all quadrants.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
21
Where considerable variation of pressure occurs over
a surface, it has been sub-divided and mean pressure
coefficients given for each of its several parts.
In addition, areas of high local suction (negative
pressure concentration) frequently occurring near the
edges of walls and roofs are separately shown.
Coefficients for the local effects should only be used
for calculation of forces on these local areas affecting
roof sheeting, glass panels and individual cladding
units including their fixtures. They should not be used
for calculating force on entire structural elements such
as roof, walls or structure as a whole.
NOTES
1 The pressure coefficients given in the different tables have
been obtained mainly from measurements on models in wind
tunnels, and the great majority of data available have been
obtained in conditions of relatively smooth flow. Where
sufficient field data exist as in the case of rectangular buildings,
values have been obtained to allow for turbulent flow.
2 In recent years, wall glazing and cladding design has been a
source of major concern. Although of less consequence than
collapse of the main structures, damage to glass can be
hazardous and cause considerable financial losses.
3 For pressure coefficients for structures not covered herein,
reference may be made to specialist literature on the subject
or advise may be sought from specialists in the subject.
4.5.2.1 Wind load on individual members
When calculating the wind load on individual structural
elements such as roofs and walls, and individual
cladding units and their fittings, it is essential to take
account of the pressure difference between opposite
faces of such elements or units. For clad structures, it
is, therefore, necessary to know the internal pressure
as well as external pressure. Then the wind load,
F (in N) acting in a direction normal to the individual
structural element or cladding unit is:
^ = ( C pe- C pi^d
where
C pe = external pressure coefficient;
C = internal pressure coefficient;
A - surface area of structural element or
cladding unit in m 2 ; and
p d = design wind pressure in N/m 2
NOTES
1 If the surface design pressure varies with height, the surface
areas of the structural element may be sub-divided so that the
specified pressures are taken over appropriate areas.
2 Positive wind load indicates the force acting towards the
structural element and negative away from it.
4.5.2.2 External pressure coefficients
a) Walls — The average external pressure
coefficient for the walls of clad buildings of
rectangular plan shall be as given in Table 7.
In addition, local pressure concentration
coefficients are also given.
b) Pitched Roofs of Rectangular Clad Buildings
— The average external pressure coefficients
and pressure concentration coefficients for
pitched roofs of rectangular clad building
shall be as given in Table 8. Where no
pressure concentration coefficients are given,
the average coefficients apply. The pressure
coefficients on the underside of any over-
hanging roof shall be taken in accordance with
4.5.2.2 (g).
NOTES
1 The pressure concentration shall be assumed to act
outward (suction pressure) at the ridges, eaves, cornices
and 90° corners of roofs.
2 The pressure concentration shall not be included
with the net external pressure when computing overall
loads.
c) Monoslope Roofs of Rectangular Load
Buildings — The average pressure coefficient
and pressure concentration coefficient for
monoslope (lean-to) roofs of rectangular clad
buildings shall be as given in Table 9.
d) Canopy Roofs with l A < hlw < 1 and 1 < L/w < 3
— The pressure coefficients are given in
Tables 10 and 11 separately for monopitch
and double pitch canopy roofs, such as open-
air parking garages, shelter areas, outdoor
areas, railway platforms, stadiums and
theatres. The coefficients take account of the
combined effect of the wind exerted on and
under the roof for all wind directions; the
resultant is to be taken normal to the canopy.
Where the local coefficients overlap the
greater of the two given values should be
taken. However, the effect of partial closures
of one side and or both sides, such as those
due to trains, buses and stored materials shall
be foreseen and taken into account.
The solidity ratio is equal to the area of
obstruction under the canopy divided by the
gross area under the canopy, both areas
normal to the wind direction. = represents
a canopy with no obstructions underneath.
= 1 represents the canopy fully blocked with
contents to the downwind eaves. Values of
C for intermediate solidities may be linearly
interpolated between these two extremes, and
apply upwind of the position of maximum
blockage only. Downwind of the position of
maximum blockage the coefficients for =
may be used.
In addition to the pressure forces normal to
22
NATIONAL BUILDING CODE OF INDIA
Table 7 External Pressure Coefficients (C ) for Walls of Rectangular Clad Buildings
[C/aii5e 4.5.2.2 (a)]
Building
Height Ratio
Building
Plan Ratio
Elevation
Plan
Wind
Angle
Degree
Cpe for Surface
Local
A
B
C
D
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
i<ia
w 2
j— — w — »-|
1.
h
t
D
90
+0.7
-0.5
-0.2
-0.5
-0.5
+0.7
-0.5
-0.2
I
-0.8
*<I
—1 U— 0.25w
w 2
3 ' „
2 w
c
90
+0.7
-0.5
-0.25
-0.5
-0.6
+0.7
-0.6
-0.1
V
B
i
-1.0
D
i<i s l
w 2
D
90
+0.7
-0.6
-0.25
-0.6
-0.6
+0.7
-0.6
-0.25
!
-1.1
1/^3
— < — < —
2 w 2
3 ' „
-< — <4
2 w
C
90
+0.7
-0.5
-0.3
-0.5
-0.7
+0.7
-0.7
-0.1
1
V
B
-1.1
D
i<ia
w 2
D
90
+0.8
-0.8
-0.25
-0.8
-0.8
+0.8
-0.8
-0.25
I
-1.2
3 ,* *
-<1— <6
3 > „
— < — <4
2 w
C
90
+0.7
-0.5
-0.4
-0.5
-0.7
+0.8
-0.7
-0.1
:
!
1
2 w
B
-1.2
D
/ _3
w~2
1 = 1.0
1 = 2
90
+0.95
-0.8
-1.85
-0.8
-0.9
+0.9
-0.9
-0.85
I
1 .
C
-1.25
V
B
1,6
w
^
i
90
+0.95
-0.7
-0.25
-0.7
-0.7
+0.95
-0.7
-1.25
-1.25
90
+0.85
-0.75
-0.75
-0.75
-0.75
+0.85
-0.75
-0.75
-1.25
NOTE — h is the height of eaves or parapet, / is the greater horizontal dimension of a building and w is the lesser horizontal
dimension of a building.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
23
Table 8 External Pressure Coefficients (C^) for Pitched Roofs of Rectangular Clad Buildings
[Clause 4.5.2.2 (b)]
Building Height Ratio
Roof
Wind Angle 6
Wind Angle 6
Local Coefficients
Angle
degrees
0°
90°
EF
GH
EG
FH
mm
M
^^
B
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
<9)
(10)
*■ — w — ■-
5
-0.8
-0.9
-0.4
-0.4
-0.8
-0.8
-0.4
-0.4
-2.0
-1.4
-2.0
-1.2
-2.0
-1.2
-1.0
10
20
30
-1.2
-0.4
o
-0.4
-0.4
04
-0.8
-0.7
-07
-0.6
-0.6
-0.6
-0.6
-1.4
-1.0
-0.8
-1.4
-1.2
w 2
-1.2
-1.1
-1.1
h— '
45
+0.3
-0.5
-0.7
60
+0.7
-0.6
-0.7
-0.6
-1.1
-» — w — mK
5
-0.8
-0.9
-0.6
-0.6
-1.0
-0.9
-0.6
-0.6
-2.0
-2.0
-2.0
-2.0
-2.0
-1.5
-1.0
10
-1.1
-0.6
-0.8
-0.6
-2.0
-2.0
-1.5
-1.2
1 h ^ 3
— < — s —
2 w 2
20
-0.7
-0.5
-0.8
-0.6
-1.5
-1.5
-1.5
-1.0
h
♦
30
45
60
-0.2
+0.2
+0.6
-0.5
-0.5
-0.5
-0.8
-0.8
-0.8
-0.8
-0.8
-0.8
-1.0
-1.0
— W m.
-0.7
-0.6
-0.9
-0.7
-2.0
-2.0
-2.0
—
y\
5
-0.7
-0.6
-0.8
-0.8
-2.0
-2.0
-1.5
-1.0
x
^ ^
n
10
-0.7
-0.6
-0.8
-0.8
-2.0
-2.0
-1.5
-1.2
3 ft .
-< — <6
2 w
1
h
20
30
-0.8
-1.0
-0.6
-0.5
-0.8
-0.8
-0.8
-0.7
-1.5
-1.5
-1.5
-1.5
-1.2
40
-0.2
-0.5
-0.8
-0.7
-1.0
W
50
60
+0.2
+0.5
-0.5
-0.5
-0.8
-0.8
-0.7
-0.7
NOTES
1 h is the height to caves or parapet, w is the lesser horizontal dimension of a building.
2 Where no local coefficients are given the overall coefficients apply.
WIND
KEY PLAN
v = h or 0.15 w,
whichever is the lesser
24
NATIONAL BUILDING CODE OF INDIA
Table 9 External Pressure Coefficients (C ) for Monoslope Roofs for Rectangular
pe
[Clause 4.5.2.2(c)]
WIND
I H.
H 1
H-
ha 4_iia- T -
I
lUzzi
.X-
-w-
II II
w
y = h or 0.15 w, whichever is the lesser
V?*
*sr
NOTE — Area H and area L refer to the whole quadrant.
OVERALL COEFFICIENTS
Roof Angle
Wind Angle $
0°
45°
90°
135°
180°
Degree
H
L
H
L
H&L
H&L
H
L
H
L
5
10
15
20
25
30
-1.0
-1.0
-0.9
-0.8
-0.7
-0.5
-0.5
-0.5
-0.5
-0.5
^0.5
-0.5
-1.0
-1.0
-1.0
-1.0
-1.0
-1.0
-0.9
-0.8
-0.7
^0.6
-0.6
^0.6
Applies to length wll
from wind ward end
-1.0
-1.0
-1.0
-0.9
-0.8
^0.8
Applies to
remainder
-0.5
-0.5
-0.5
-0.5
-0.5
-0.5
-0.9
-0.8
-0.6
-0.5
^0.3
-0^
-1.0
-1.0
-1.0
-1.0
^0.9
^0.6
-0.5
-0,4
-0.3
^0.2
^0.1
-1.0
-1.0
-1.0
-1.0
^0.9
-0.6
Roof Angle
LOCAL COEFFICIENTS C^
,/*-
Degree
Hi
H 2
U
u
H
L
5
-2.0
-1.5
-2.0
-1.5
-2.0
-2.0
10
-2.0
-1.5
-2.0
-1.5
-2.0
-2.0
15
-1.8
-0.9
-1.8
-1.4
-2.0
-2.0
20
-1.8
-0.8
-1.8
-1.4
-2.0
-2.0
25
-1.8
-0.7
-0.9
^0.9
-2.0
-2.0
30
-1.8
^0.5
^0.5
^0.5
-2.0
-2.0
NOTE — h is the height to eaves at lower side, / is greater horizontal dimension of a building and w is the lesser horizontal
dimension of a building.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
25
Table 10 Pressure Coefficients for Free Standing Monosioped Roofs
[Clause 4.5.2.2(d)]
ROOF ANGLE
SECTION
I
-W/10
— w-
i
L/10 "
r
L/10w
— Iw /
10
KEY PLAN
Roof Angle
Solidity Ratio
Maximum (Largest +ve) and Minimum (Largest
Pressure Coefficients
-ve)
Overall
coefficients
Local coefficients
Degree
1 1
Y///A
I^SI
+0.2
+0.5
+1.8
+1.1
5
+0.4
+0.8
+2,1
+1.3
10
+0.5
+1.2
+2.4
+1.6
15
All values of
+0.7
+1.4
+2.7
+1.8
20
+0.8
+1.7
+2.9
+2.1
25
+1.0
+2.0
+3.1
+2.3
30
+1.2
+2,2
+3,2
+2,4
=
-0.5
-0.6
=1.3
-1.4
0=1
-1.0
-1.2
-1.8
-1.9
5
=
-0.1
-1.1
-1.7
-1.8
0=1
-1.1
-1.6
-2.2
-2.3
10
=
-0.9
-1.5
-2.0
-2.1
0=1
-1.3
-2.1
-2.6
-2.7
15
=
-1.1
-1.8
-2,4
-2.5
0=1
-1.4
-2.3
-2.9
-3.0
20
=
-1.3
-2,2
-2,8
-2,9
0=1
-1.5
-2.6
-3.1
-3.2
25
=
-1.6
-2,6
-3.2
-3,2
0=1
-1.7
-2.8
-3.5
-3.5
30
=
-1.8
-3.0
-3.8
-3,6
0=1
-1.8
-3.0
-3.8
-3.6
NOTE — For monopitch canopies the centre of pressure should be taken to act at 0.3 w from the windward edge.
26
NATIONAL BUILDING CODE OF INDLA
Table 11 Pressure Coefficients for Free Standing Double Sloped Roofs
[Clause 4.5.2.2 (d)]
-ve ROOF ANGLE
+ve ROOF ANGLE
W/10-
H
m
W/10-
EgE^
L/10 "
r
-W/10
-W-
i
1
L/10
T
-W/10
KEY PLAN
Roof Angle
Solidity Ratio
Maximum (Largest +ve) and Minimum (Largest -ve) Pressure Coefficients
Overall
coefficients
Local coefficients
WZ\
Degree
1 1
fc^
t=l
-20
+0.7
+0.8
+1.6
+0.6
+ 1.7
-15
+0.5
+0.6
+1.5
+0.7
+ 1.4
-10
+0.4
+0.6
+1.4
+0.8
+1.1
-5
+0.3
+0.5
+1.5
+0.8
+0.8
+5
+10
AH values of
+0.3
+0.4
+0.6
+0.7
+1.8
+1.8
+1.3
+1.4
+0.4
+0.4
+15
+0.4
+0.9
+1.9
+1.4
+0.4
+20
+0.6
+1.1
+1.9
+1.5
+0.4
+25
+0.7
+1.2
+1.9
+1.6
+0.5
+30
+0.9
+1.3
+1.9
+ 1.6
+0.7
-20
=
-0.7
-0.9
-1.3
-1.6
-0.6
0=1
-0.9
-1.2
-1.7
-1.9
-1.2
-15
=
-0.6
-0.8
-1.3
-1.6
-0.6
0=1
-0.8
-1.1
-1.7
-1.9
-1.2
-10
=
-0.6
-0.8
-1.3
-1.5
-0.6
0=1
-0.8
-1.1
-1.7
-1.9
-1.3
-5
=
-0.5
-0.7
-1.3
-1.6
-0.6
0=1
-0.8
-1.5
-1.7
-1.9
-1.4
+5
=
-0.6
-0.6
-1.4
-1.4
-1.1
0=1
-0.9
-1.3
-1.8
-1.8
-2.1
+10
=
-0.7
-0.7
-1.5
-1.4
-1.4
0=1
-1.1
-1.4
-2.0
-1.8
-2.4
+15
=
-0.8
-0.9
-1.7
-1.4
-1.8
0=1
-1.2
-1.5
-2.2
-1.9
-2.8
+20
=
-0.9
-1.2
-1.8
-1.4
-2.0
0=1
-1.3
-1.7
-2.3
-1.9
-3.0
+25
=
-1.0
-1.4
-1.9
-1.4
-2.0
0=1
-1.4
-1.9
-2.4
-2.1
-3.0
+30
=
-1.0
-1.4
-1.9
-1.4
-2.0
0=1
-1.4
-2.1
-2.6
-2.2
-3.0
NOTE — Each slope of a duopitch canopy should be able to withstand forces using both the maximum and the minimum coefficients,
and the whole canopy should be able to support forces using one slope at the maximum coefficient with the other slope at the
minimum coefficient. For duopitch canopies the centre of pressure should be taken to act at the centre of each slope.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
27
the canopy, there will be horizontal loads on
the canopy due to the wind pressure on any
fascia and to friction over the surface of the
canopy. For any wind direction, only the
greater of these two forces need be taken into
account. Fascia loads should be calculated on
the area of the surface facing the wind, using
a force coefficient of 1.3. Frictional drag
should be calculated using the coefficients
given in 4.5.3.1.
e)
NOTE — Tables 12 to 17 may be used to get internal
and external pressure coefficients for pitches and
troughed free roofs for some specific cases for which
aspect ratios and roof slopes have been specified.
However, while using Tables 12 to 17 any significant
departure from it should be investigated carefully. No
increase shall be made for local effects except as
indicated.
Curved Roofs — For curved roofs, the
external pressure coefficients shall be as given
in Table 18. Allowance for local effects shall
be made in accordance with Table 8.
Table 12 Pressure Coefficients (Top and Bottom) for Pitched Roofs, a = 30°
[Clause 4.5.2.2 (d)]
b' = d
b = 5d
a = 30°
6 = 0°-45°, D,D', E, E'fulll
6 = 90°, D, D\ E, E'part length b*
PRESSURE COEFFICIENTS, C p
e
D
D'
E
E'
End Surfaces
C
C'
G
G'
0°
0.6
-1.0
-0.5
-0.9
—
—
—
—
45°
0.1
-0.3
-0.6
-0.3
—
_.
_
—
90°
-0.3
-0.4
-0.3
-0.4
-0.3
0.8
0.3
-0.4
45°For;: C p top = -1.0; C p bottom = -0.2.
90°Tangentially acting friction: /?9o°= 0.05 p 6 .db.
28
NATIONAL BUILDING CODE OF INDIA
Table 13 Pressure Coefficients (Top and Bottom) for Pitched Free Roofs, a = 30°
with Effects of Train or Stored Materials
[Clause 4.5.2.2 (d)]
b = 5d
a = 30°
Effects of trains or stored materials:
e = 0°~45°, or 135° -180°, D,D",E, E'fuH'length
e = 90°, D, d; E, E'part length b'
PRESSURE COEFFICIENTS, C P
D
D'
E
E'
End Surfaces
C
C
G
G'
0°
0.1
0.8
-0.7
0.9
—
—
—
—
45°
-0.1
0.5
-0.8
0.5
—
—
— .
—
90°
-0.4
-0.5
-0.4
-0.5
-0.3
0.8
0.3
-0.4
180°
-0.3
0.6
0.4
. -0.6
—
—
'— '
—
45°F6ry: C p top = -1.5; C p bottom = 0.5.
90°Tangentially acting friction: Rw = 0.05 p&.db.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
29
Table 14 Pressure Coefficients (Top and Bottom) for Pitched Free Roofs, a = 10°
[Clause 4.5.2.2 (d)]
C
b = 5d
b' = d
a = 10°
8 = 0°-45°, D, D',E, E'full length
= 90°, a D r , E, E'part length b'
PRESSURE COEFFICIENTS, C p
D
D r
E
E'
End Surfaces
C
c
G
G'
0°
-1.0
0.3
-0.5
0.2
__
—
—
—
45°
-0.3
0.1
-0.3
0.1
—
—
—
—
90°
-0.3
0.0
-0.3
0.0
-0.4
0.8
0.3
-0.6
0° For/- C p top = -1 .0; C p bottom = 0.40.
0-90° Tangentially acting friction: R^ = 0. 1 p d .db.
30
NATIONAL BUILDING CODE OF INDIA
Table 15 Pressure Coefficients (Top and Bottom) for Pitched Free Roofs, a = 10°
with Effects of Train or Stored Materials
[Clause 4.5.2.2 (d)]
a = 10°
Effects of trains or stored materials:
9 = 0°~45°, 135°-180°, D, D', E, E'full length
9 = 90°, D, D\ E, E'part length b'
PRESSURE COEFFICIENTS, C p
e
D
D f
E
E'
i rm . ■■ 'V ..-.I ... i ii in
End Surfaces
C
C
G
■■■■'i-G': 7 .
0°
-1.3
0.8
-0.6
0.7
—
—
— •
—
45°
0.5
0.4
-0.3
0.3
—
—
_
—
90°
-0.3
0.0
-0.3
0.0
—
—
—
-^~
180°
-0.4
-0.3
-0.6
-0.3
-0.4
0.8
OS
-m
0° For/: C p top = -1 .6; C p bottom = 0.9.
0°- 180° Tangentially acting friction: R^ = 0.1 p d .db.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
31
Table 16 Pressure Coefficients for Troughed
Free Roofs, a = 10°
[Clause 4.5.2.2 (d)]
Table 17 Pressure Coefficients for Troughed
Free Roofs, a = 10° with Effects of
Trains or Stored Materials
[Clause 4.5.2.2 (d)]
h' = 0.8h-
X
b = 5d
b' = d
n Rgo-
4> f = 0.
2d
Wi
m
w
%
— m —
Roof slope a - 10°
= 0° - 45°, D, D\ E, E'full length
e = 90°, D, D',E, E' part lengths
PRESSURE COEFFICIENTS, C p
e
D
D'
E
E'
0°
0.3
-0.7
0.2
-0.9
45°
0.0
-0.2
0.1
-0.3
90°
-0.1
0.1
-0.1
0.1
0° For/: C p top = 0.4; C p bottom = 1.5.
0° - 90° Tangentially acting friction: /?9o° = 0.1 pd-bd.
^^
>4 d
LA...
b = 5d
1 1
L
Roo-
ty =d
Roof slope a = 10°
Effects of trains or stored materials:
6 = 0°-45°,or 135°- 180°, D, D', E, E'full length
6 = 90°, D, D', E, E' part length b'
PRESSURE COEFFICIENTS, C p
e
D
D'
E
E'
0°
-0.7
0.8
-0.6
0.6
45°
-0.4
0.3
-0.2
0.2
90°
-0.1
0.1
-0.1
0.1
180°
-0.4
-1.2
-0.6
-0.3
0° For/: C p top = 1 . 1 ; C p bottom = 0.9.
0° - 180° Tangentially acting friction: Rw = 0.1 p d .bd.
32
NATIONAL BUILDING CODE OF INDIA
Table 18 External Pressure Coefficients for Curved Roofs
[Clause 4.5.2.2 (e)]
a) ROOF SPRINGING FROM GROUND LEVEL
C
WIND
+ 0.8
1
■0.6
b) ROOF ON ELEVATED STRUCTURE
-WINDWARD
^QUARTER
PORTION OF ROOF
BELOW THIS LINE
TO BE TREATED AS
AN EXTENSION OF
VERTICAL SUPPORTS
CENTRAL HALF (C)
-0.6
c) DOUBLY CURVED ROOFS
H h
— > 0.6 and - > 0.6
/ /
LEEWARD [ Av
QUARTER (0.4) h
i «
Values of Cd and C 2
Hll
C
c,
c 2
0.1
-0.8
+0.1
-0.8
0.2
-0.9
+0.3
-0.7
0.3
-1.0
+0.4
-0.3
0.4
-1,1
+0.6
+0.4
0.5
-1.2
+0.7
+0.7
NOTE — When the wind is blowing normal to the gable ends, C^ may be taken as equal to -0.7 f or the full width of the roof over i
length of 111 from the gable ends and -0.5 for the remaining portion.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
33
Pitched and Saw-Tooth Roofs of Multi-span
Buildings — For pitched and saw-tooth
roofs of multi-span buildings, the external
average pressure coefficients and pressure
concentration coefficients shall be as given
in Tables 19 and 20 respectively, provided
that all spans shall be equal and the height to
the eaves shall not exceed the span.
NOTE — Evidence on multi-span buildings is
fragmentary. Any departure given in Tables 19 and 20
should be investigated separately.
Table 19 External Pressure Coefficients (C ) for Pitched Roofs of Multi-span Buildings
(All Spans Equal) with h > w '
[Clause 4.5.2.2(f)]
y = /)OR0.1w
WHICHEVER IS
LESSER
1
h
1
SECTION
Roof Angle
Wind Angle
First
Span
First Intermediate Span
Other Intermediate
Span
End Span
Local Coefficient
degrees
degrees
e
a
b
c
d
m
n
X
z
a
^
WA
5
-0.9
-0.6
-0.4
-0.3
-0.3
-0.3
-0.3
-0.3
10
-1.1
-0.6
-0.4
-0.3
-0.3
-0.3
-0.3
-0.4
20
-0.7
-0.6
-0.4
-0.3
-0.3
-0.3
-0.3
-0.5
-2.0
-1.5
30
-0.2
-0.6
-0.4
-0.3
-0.2
-0.3
-0.2
-0.5
45
+0.3
-0.6
-0.6
-0.4
-0.2
-0.4
-0.2
-0.5
Roof Angle
degrees
Wind Angle
degrees
e
Distance
a
hi
hi
to
Up to 45
90
-0.8
-0.6
-0.2
Frictional drag: when wind angle 9 = 0° horizontal forces due to frictional drag are allowed for in the above values;
when wind angle = 90° allow for frictional drag in accordance with 4.5.3.1.
NOTE — Evidence on these buildings is fragmentary and any departures from the cases given should be investigated separately.
34
NATIONAL BUILDING CODE OF INDIA
Table 20 External Pressure Coefficients (C„ e ) for Saw-Tooth Roofs of Multispan Buildings
(All Spans Equal) with h > w'
mis,,,*.,, a < n n mi
wu^twun
" "■ "■ " ■■" ML H t
V
N^
■ l^'n^ww^v^
W
^^^^^^^^^^
irint^rrrrr^
W
mw 1 1 >y> i > i
w
Wft
■*— w' — *-
_L
f
\\^*<{<((€<(<\
■*— w' — ■*
9 1 \W. W 999 99999 A
— *H r^— u. i w
J1L
W
^te^rflfe^^Mfe^
* + ^W<<{(((€<<
—— w' — *-
W-%- J.
IT H 7
1
n^nm^n^n^n
W'
ROOF PI AN
y = /?OR0.1w
WHICHEVER IS
LESSER
stu I ION
ttiiiu migKi
degrees
I'll 91 k7pdll
Span
AtkAK Intdnnuliafa
UtUVi lUH-tiuvuiaiv
Span
Coefficient
(9
fl
b
c
d
m
n
JC
z
^
EZZ\
ISO
+0.6
-0.5
-0.7
-0.3
-0.7
-0.3
-0.4
^0.3
-0.3
^0.4
-0.2
^0.6
-0.1
^0.6
-0.3
^0.1
-2.0
-1.5
Wind Angle
Distance
uCgI££S
__ ma *^_
* —
""—*»*
hi
hi
«3
90
-0.8
-0.6
-0.2
270
Similarly, but handed
Frictional drag: when wind angle = 0° horizontal forces due to factional drag are allowed for in the above values;
when wind angle - 90°aiiow for frictional drag in accordance with 4.5.3.1.
NOTE — Evidence on these buildings is fragmentary and any departures from the cases given should be
investigated separately.
PART 6 STRUCTURAL DESIGN— SECTION 1 LOADS, FORCES AND EFFECTS
35
g) Pressure Coefficients on Overhangs from
Roofs — The pressure coefficients on the top
overhanging portion of the roofs shall be
taken to be the same as that of the nearest top
portion of the non-pressure coefficients for
the underside surface of the overhanging
portions shall be taken as follows and shall
be taken as positive if the overhanging portion
is on the windward side:
1) 1.25, if the overhanging slopes;
downwards;
2) 1 .0, if the overhanging is horizontal; and
3) 0.75, if the overhanging slopes upwards.
For overhanging portions on sides other than
windward side, the average pressure coefficients
on the adjoining walls may be used.
h) Cylindrical Structures — For the purpose of
calculating the wind pressure distribution
around a cylindrical structure of circular
cross-section, the value of external pressure
coefficients given in Table 21 may be used
provided that the Raynolds number is greater
than 10 000. They may be used for wind
blowing normal to the axes of cylinders
having axis normal to the ground plane (that
is, chimneys and silos) and cylinders having
their axis parallel to the ground plane (that is,
horizontal tanks) provided that the clearance
between the tank and the ground is not less
than the diameter of the cylinder.
h is the height of a vertical cylinder or length
of a horizontal cylinder. Where there is a free
flow of air around both ends, h is to be taken
as half the length when calculating h/D ratio.
1) -0.8, where h/D is not less than 0.3; and
2) -0.5, where h/D is less than 0.3.
Table 21 External Pressure Distribution Coefficients Around Cylindrical Structures
[Clause 4.5.2.2 (h)]
mmmmzwA
Position of Periphery,
Pressure Coefficient, Cpe
in degrees
H/D = 25
H/D = 7
H/D= 1
1.0
1.0
1.0
15
0,8
0.8
0.8
30
0.1
0.1
0.1
45
-0.9
-0.8
-0.7
60
-1.9
-1.7
-1.2
75
-2.5
-2.2
-1.6
90
-2.6
-2.2
-1.7
105
-1.9
-1.7
-1.2
120
-0.9
^0.8
-0.7
135
-0.7
-0.6
-0.5
150
-0.6
-0,5
-0.4
165
-0.6
-0.5
-0.5
180
-0.6
-0.5
-0.4
36
NATIONAL BUILDING CODE OF INDIA
j) Roofs and Bottom of Cylindrical Related
Structure — The external pressure coefficients
for roofs and bottoms of cylindrical elevated
structures shall be as given in Table 22 (see
also Fig. 2).
The total resultant load (P) acting on the roof
of the structure is given by the following
formula:
P = 0.785 D*(C p ,-C pe )/> d
The resultant of P for roofs lies at 0. 1 D from
the centre of the roof on the windward side.
k) Combined Roofs and Roofs with a Sky Light
— The average external pressure coefficients
for combined roofs and roofs with a sky light
are shown in Table 23.
0.2D<h<3D
tana <0.2
m
SECTION AA
Cpe = -1.5_/
Cpe = - 0.5
Cpe = -1.0
0.5 D FOR 2 < h / D < 3
0.15 h + 0.2 D FOR 0.2 < h / D < 2
PLAN
(For force coefficient corresponding to shell portion see Table 23)
Fig. 2 External Pressure Coefficients on the Upper Roof Surface of Singular
Circular Standing on the Ground
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
37
Table 22 External Pressure Coefficients for Roofs and Bottoms of
Cylindrical Structures
[Clause 4.5.5.2 (j)]
DIRECTION
OF WIND
Coefficient of External Pressure, C
pe
Structure According to Shape
a
b andc
d
HID
Roof
(Z/H) -1
Roof
Bottom
0.5
1.0
2.0
-0.65
-1.00
-1.00
1.00
1.25
1.50
-0.75
-0.75
-0.75
-0.8
-0.7
-0.6
Total force acting on the roof of the structure, P = 0.785 D 2 (C pi - C^)p A .
The resultant of P lies eccentrically, e = 0.1 £).
38
NATIONAL BUILDING CODE OF INDIA
Table 23 External Pressure Coefficients, C n for Combined Roofs and Roofs with a Sky Light
[Clause 4.5.2.2 (k)]
a) Combined Roofs
0.9 "
DIRECTION 1
c^^d
DIRECTION 2
y|
— i
~r t
)
ji
ai<30° y/
bi < b2 /
0.6 ■
)
' t
h 2
i
hi
0.4
y\
vs/;;;;/)/////////////
a x
u 1 - - u 2
0.2
0.13
1.2
- Cpe = 0.4 -^- 0.6
Cpe
7\
I
•
..
0.5
1<
) 1
1.!
5 /
1.8 2
2.5
3.0
H2
a
-0.2
1
\- Cpe -15-1.7
/
-0.4
J
f
DIRECTION 1
e
c^^*^
.d
DIRECTION 2
Z 1 .
J
f *
i
1
-0.6
Cpe' = 2-J£ -2'.9-/
/
/
■ ■*
-0.8
a
i -
-1.0
Values of C^
Portion Direction 1 Direction 2
a From the Diagram
C^ = -0.5, Mb < 1.5 ~°' 4
b Cpe = -0.7,fti/ft 2 >1.5
candd See Table 5
e See 4.5.2.2 (g)
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
39
Table 23 — Concluded
b) Roofs with a Sky Light
DIRECTION
OF WIND
:: 7^r7777777777777777777ZR7y
DIRECTION
OF WIND
b r
vM/J/J/JMM^.w/fM'MJV/*
-b^I
^1>^2
Portion
-0.6
+0.7
&i<*l
See Table for
Combined Roofs
m) Grandstands — The pressure coefficients on
the roof (top and bottom) and rear wall of a
typical grandstand roof, which is open on
three sides, is given in Table 24. The pressure
coefficients are valid for a particular ratio of
dimensions as specified in Table 24, but may
be used for deviations up to 20 percent. In
general, the maximum wind load occurs,
when the wind is blowing into the open front
of the stand causing positive pressure under
the roof and negative pressure on the roof.
n) Upper Surface of Round Silos and Tanks —
The pressure coefficients on the upper surface
of round silos and tanks standing on ground
shall be as given in Fig. 2.
p) Spheres — The external pressure coefficients
for spheres shall be as given in Table 25.
4.5.2.3 Internal pressure coefficients
Internal air pressure in a building depends upon the
degree of permeability of the cladding to the flow of
air. The internal air pressure may be positive or
negative depending on the direction of flow of air in
relation to the openings in the buildings.
a) In the case of buildings where the claddings
permit the flow of air with openings not more
than about 5 percent of the wall areas but
where there are no large openings, it is
necessary to consider the possibility of the
internal pressure being positive or negative.
40
NATIONAL BUILDING CODE OF INDIA
Table 24 Pressure Coefficients at Top and Bottom Roof of Grandstands
Open Three Sides (Roof = 5°)
[Clause 4.5.2.2 (m)]
(h:b:l = 0.8: 1:2.2)
y///////////////////////////// —
WIND
Front and Back of Wall
e
J
K
L
M
o° ,
+0.9
-OS
+0.9
-0.5
45°
+0.8
-0.6
+0.4
-0.4
135°
-1.1
+0.6
-1.0
+0.4
180°
-03
+0.9
-0.3
+0.9
60°
A^-CpofX^-1.0
60°
M w -C p of/=+1.0
( Shaded area to scale )
Top and Bottom of Roof
e
A
B
C
D
E
F
G
.■-..■ B
0°
-1.0
+0.9
-1.0
+0.9
-0.7
+0.9
+0.7
+0.9
45°
-1.0
+0.7
-0.7
+0.4
-0.5
+0.8
-0.5
+0.3
135°
-0.4
-1.1
-0.7
-1.0
-0.9
-1.1
-0.9
!0
180°
-0.6
-0.3
-0.6
-0.3
-0.6
-^0.3
-0.6
-0.3
45°
Mr -C P (top) = -2.0
45°
Af R - C P (bottom) = -
(-1.0
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
41
Table 25 Kxternai Pressure Distribution Coefficients Around Spherical Structures
[Clause 4.5.2.2 (p)|
t*D-*-i
Position of Periphery,
c
Remarks
in degrees
+1.0
15
+0.9
Q - 0.5forW 2 <7
30
+0.5
= 0.2forDV z >7
45
-0.1
60
-0.7
75
-1.1
90
-1.2
105
-1.0
120
-0.6
135
-0.2
150
+0.1
165
+0.3
180
+0.4
Two design conditions shall be examined, one
with an internal pressure coefficient of
+0,2 and another with an internal pressure
coefficient of -0,2,
The internal pressure coefficient is algebraically
added to the external pressure coefficient and
the analysis, which indicates greater distress
of the member shall be adopted. In most
situations, a simple inspection of the sign of
the external pressure will at once indicate the
proper sign of the internal pressure coefficient
to be taken for design.
NOTE — The terms normal permeability relates to the
now of air commonly afforded by the claddings not
only through the open windows and doors, but also
through the slits round the closed windows and doors
and through chimneys, ventilators and through the joints
between roof coverings, the total open area being less
than 5 percent of the irea of the walls having the
openings.
b) Building with medium and large openings —
Buildings with medium and large openings
may also exhibit either positive or negative
internal pressure depending upon the direction
of wind. Buildings with medium openings
between about 5 to 20 percent of wall area
shall be examined for an internal pressure
coefficient of +0.5 and later with an internal
pressure coefficient of -0.5, and the members
shall be adopted. Buildings with large
openings, that is, openings larger than
42
NATIONAL BUILDING CODE OF INDIA
c)
20 percent of the wall area shall be examined
once with an internal pressure coefficient of
+0.7 and again with an internal pressure
coefficient of -0.7, and the analysis which
produces greater distress on the members shall
be adopted.
Buildings with one open side or openings
exceeding 20 percent of wall area may be
assumed to be subjected to internal positive
pressure or suction similar to those for
buildings with large openings. A few
examples of buildings with one sided
openings are shown in Fig. 3 indicating values
of internal pressure coefficients with respect
to direction of wind:
In buildings with roofs but no walls, the roofs
will be subjected to pressure from both inside
and outside, and the recommendations shall
be as given in 4.5.2.2.
4.5.3 Force Coefficients
The value of force coefficients apply to a building or
structure as a whole, and when multiplied by the
effective frontal area, A e of the building or structure
and by design wind pressure, p 6 give the total wind
load on that particular building or structure.
where F is the force acting in a direction specified in
the respective tables and C f is the force coefficient for
the building.
NOTES
1 The value of the force coefficient differs for the wind acting
on different faces of a building or structure. In order to
^T
4
I tri
B
trl
<$=>
(b) FOR l > 1
(c)FOR £=1, USE AVERAGE VALUES
(ARROWS INDICATE DIRECTION OF WIND FLOW)
Fig. 3 Large Opening in Buildings (Values of Coefficient of Internal Pressure)
(with Top Closed)
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
43
determine the critical load, the total wind load should be
calculated for each wind direction.
2 If surface design pressure varies with height, the surface area
of tbe building/structure may be sub-divided so that specified
pressure are taken over appropriate areas.
3 In tapered buildings/structures, the force coefficients shall
be applied after sub-dividing the building/structure into suitable
number of strips and the load on each strip calculated
individually, taking the area of each strip as A e .
4 Force coefficients for structures not covered herein, reference
may be made to specialist literature on the subject or advise
may be sought from specialists in the subject.
4.5.3.1 Frictional drag
In certain buildings of special shape, a force due to
frictional drag shall be taken into account, in addition
to those loads specified in 4.5.2. For rectangular clad
buildings, this addition is necessary only where the
ratio dlh or dlb is greater than 4. The frictional drag
force, F' in the direction or the wind given by the
following formulae:
If h £b,F'= C\ (d~4h) bp d + C\ W- 4h) 2hp d
or If h > b, F'=C' f (d-4b) bp d + C' f (d-4b) 2hp d
The first term in each case gives the drag on the roof
and the second on the walls. The value of C' f has the
following values:
C\ - 0.01 for smooth surfaces without
corrugations or ribs across the wind
direction;
C\ - 0.02 for surfaces with corrugations or ribs
across the wind direction;
C\ = 0.04 for surfaces with ribs across the wind
direction.
For other buildings, the frictional drag has been
indicated, where necessary, in the tables of pressure
coefficients and force coefficients.
4.5.3.2 Force coefficients for clad buildings
a) Clad buildings of uniform section — The
overall force coefficients for rectangular clad
buildings of uniform section with flat roofs
in uniform flow shall be as given in Fig. 4
and for other clad buildings of uniform section
(without projections, except where otherwise
shown) shall be as given in Table 26.
b) Buildings of circular shapes — Force
coefficients for buildings of circular cross-
section shall be as given in Table 27 (see
Fig. 5 and Annex F).
c) Low walls and hoardings — Force
coefficients for low walls and hoardings less
than 15 m high shall be as given in Table 27
provided the height shall be measured from
the ground to the top of the walls or hoarding,
and provided that for walls or hoardings above
the ground the clearance between the wall or
hoarding and the ground shall be not less than
0.25 times the vertical dimension of the wall
or hoarding.
To allow for oblique winds the design shall
also be checked for the net pressure normal
to the surface varying linearly from a
maximum of 1.7 C f at the up wind edge to
0.44 C f at the down wind edge.
The wind load on appurtenances and supports
for hoardings shall be accounted for
separately by using the appropriate net
pressure coefficients. Allowance shall be
made for the shielding effects of one element
or another,
d) Solid circular shapes mounted on a surface
— The force coefficients for solid circular
shapes mounted on a surface shall be as given
in Fig. 6.
4.6 Dynamic Effects
4.6.1 General
Flexible slender structures and structural elements shall
be investigated to ascertain the importance of wind
induced oscillations for excitations along and across
the direction of wind.
In general the following guidelines may be used for
examining the problems of wind induced oscillations:
a) Buildings and closed structures with a height
to minimum lateral dimension ratio of more
than about 5.0; or
b) Buildings and structures whose natural
frequency in the first mode is less than 1 .0 Hz.
Any building or structure which satisfies
either of the above two criteria shall be
examined for dynamic effects of wind.
NOTES
1 The fundamental natural period (rj, in seconds, of
a moment-resisting frame building without brick infil
panels and of all other buildings including with brick
infil panels may be estimated in accordance with 5.4.6.
2 If preliminary studies indicate that wind-induced
oscillations are likely to be significant, investigations
should be persued with the aid of analytical methods
or, if necessary, by means of wind tunnel tests on
models.
3 Cross wind motions may be due to the lateral
gustiness of the wind, unsteady wake flow (for example,
vortex shedding), negative aerodynamic damping or to
a combination of these effects. These cross-wind
motions can become critical in the design of tall
building structures.
4 Motions in the direction of the wind (also known as
buffeting) are caused by fluctuating wind force
associated with gusts. The excitations depend on the
gust energy available at the resonant frequency.
44
NATIONAL BUILDING CODE OF INDIA
3.0
2.5
2.0
1.5
1.0
0.5
/-20
^ JPife-
/
r*
y~Z
. ■■/
z 1
WIND
0.5 1.0 1.5 2.0 2.5 3.0
a/b ►
a) Values of C , versus a / b for h / b > 1
PLAN
v/y////////
ELEVATION
F^CfR^bh
1.4
1.2
1.0
0.8
h 1
^b " 4
L h 1
b " 2
0.5 1.0 1.5 2.0 2.5 3.0
a/b
b) Values of C f versus a/b for h / b < 1
Fig. 4 Force Coefficient for Rectangular Clad
Building in Uniform Flow
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
45
Table 26 Force Coefficients C for Clad Buildings of Uniform Section
(Acting in the Direction of Wind)
[Clause 4.3.3.Z (a)|
Plan §hnng
1/ A
m 2 /s
£\ f or W £
Up to 1/2
1
2
5
10
20
00
Aii surfaces
<6
0.7
0.7
0.7
0.8
0.9
i.o
i.2
X 1
*~ m l J b
Rough or with
projections
> A
(iec also Annex E)
Smooth
>6
0.5
0.5
0.5
0.5
0.5
0.6
0.6
1
i
— — d— -i i
I T
Ellipse bid- 1/2
< 10
0.5
0.5
0.5
0.5
0.6
0,6
07
"1 h
> 10
2
2
2
2
a i
a o
A n
i
f
1
—i
i
Eiiipse bid = 2
<8
0.8
0.8
0.9
in
I.I
1.3
1.7
/ X f
' I 1
"^ I i n
1 J T
\ / 1
\ J 1
>» o
t\ o
\i,0
n o
1.0
1.1
1.3
1.5
bid-\
rib = 1 /3
< 4
n a
n a
n n
\j. i
A O
A O
i n
l.KJ
\
N — r
l J
>4
0.4
0.4
0.4
0.4
0.5
0.5
0.5
l\ 1
1 \__ 1
£/a = I
r//>= 1/6
< 10
0.7
0.8
0.8
0.9
1.0
1.0
1.3
1
1
\
> 10
0.5
0.5
0.5
0.5
0.6
0.6
0.6
— — -
- j __ ■
r/b =1/2
<3
0.3
0.3
0.3
0.3
0.3
0.3
0.4
r x i :
7 ¥
> 3
0.2
0.2
0.2
0.2
0.3
0.3
0.3
ua = i n
rib = 1/6
All values
0.5
0.5
0.5
0.5
0.6
0.6
0.7
— \j —
—
L<" -si
X
N — r
V. J
\ i
b
t
bid =2
r ju^ 1/12
All values
0.9
0.9
i.o
l.i
i.2
1.5
1.9
"0
1
1
I
b
i
1
1
I^AllUrNAL BUlLUirNU tUUfi Uf irNlMA
Table 26 — Continued
Plan Shape
V z 6
m 2 /s
C, for Height/Breadth Ratio
Up to 1/2
1
2
5
10
20
00
<6
0.7
0.8
0.8
0.9
1.0
1.2
1.6
r *\l i
1
b
All surfaces
.__
bld = 2
rib = 1/4
w ♦
>6
0.5
0.5
0.5
0,5
0.5
0.6
0.6
*17N
<10
0.8
0.8
0.9
1.0
1.1
1.3
1.5
-M^
3 r/a = l/3
>10
0.5
0.5
0.5
0.5
0.5
0.6
0.6
- ^S
\s
r/a =1/12
All values
0.9
0.9
0.9
1.1
1.2
1.3
1.6
-A.
y/^
— *■ \x 1 X
^,
rla = 1/48
All values
0.9
0.9
0.9
1.1
1.2
13
1.6
^
1
<11
0.7
0.7
0.7
0.8
0.9
1.0
1.2
— &-<
rib ~ 1/4
UN
(—— d— »n
>H
0.4
0.4
0.4
0.4
0,5
0.5
0.5
s*
1
~^
b
r/fc=l/12
All values
0.8
0.8
0.8
1.0
LI
1.2
1.4
y
1
— " <v.
b
j
rib = 1/48
All values
0.7
0.7
0.8
0.9
1.0
1.1
1.3
\
PART 6 STRUCTURAL DESIGN— SECTION 1 LOADS, FORCES AND EFFECTS
47
Table 26 — Concluded
Plan
(Shape
m 2 /s
C t for Height/Breadth Ratio
Up to 1/2
1
2
5
10
20
00
<8
0.7
0.7
0.8
0.9
1.0
1.3
n
%
— *- b
Ts
r/b=l/4
*<\
£— a-*-<
>8
0.4
0.4
0.4
0.4
0.5
0.5
0.5
—
D>
1/48 < r/fc
< 1/12
All values
1.2
1.2
1.2
1.4
1.6
1.7
2.1
• -v
<12
0.7
0.7
0.8
0.9
1.0
1.1
1.3
_^ f— d— 4
12 sided
polygon
C7
>12
0.7
0.7
0.7
0.7
0,8
0.9
1.1
-O
Octagon
All values
1.0
1.0
1.1
1.2
1.2
1.3
1.4
-o
Hexagon
All values
1.0
1.1
1.2
1.3
1.4
1.4
1.5
NOTE — Structures that, because of their size and the design wind velocity, are in the supercritical flow regime may need further
calculation to ensure that the greatest loads do not occur at some wind speed below the maximum when the flow will be sub-
critical.
The coefficients are for buildings without projections, except where otherwise shown. In this table V b is used as an indication of the
airflow regime.
48
NATIONAL BUILDING CODE OF INDIA
1.4
1.2
1.0
O.S
0.6
0.4
0.2
FOR
3X10 4 <Re
< 1
o 5 ,
C
1 +
ire-
D
.2
e
D
X10 3
60
40
20
10 ^
f.5
1.0
0.5
_
i
j
F*10>
//
fi!
^zr
5.0=^
_ 4.0^
3,0 -^
2.0 —
r -
^~
^^
0.1
0.05
Cf
D
0.01
0.002
f
1
1 1 ■ — ■ ■ [
= DRAG COEFFICIENT
E
I
XTR
I
1
1 1
^1 ATFP v/ai t ice
1 1
JLM 1 CL
1
I
uc%;
10 5 2 3 4 5 6 8 10 6 2 3 4 5 6 8 10 7 2 3 4 5 6 8 10 8
Re ►
Q
Fig. 5 Variation of 1+ 2e with Re < 3 x 10 4 for Circular Sections
Table 27 Force Coefficients for Low Walls or Hoardings (<15 m High)
[Clause 4.5.3.2(b)]
ABOVE GROUND h' > 0.25 h
ONE EDGE ON GROUND
(Wind normai to face)
Width to Height Ratio, bfh
Drag Coefficient, Ct
Wall above ground
Wall on ground
From 0.5 to 6
From 1 to 12
1.2
10
20
1.3
16
32
1.4
20
40
1.5
40
80
1.7
60
120
1.8
80 or more
160 more 20
2.0
FAR I 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
49
SIDE ELEVATION
DESCRIPTION OF SHAPE
CIRCULAR DISC
1.2
W/////////M
HEMISPHERICAL BOWL
1.4
HEMISPHERICAL BOWL
0.4
HEMISPHERICAL SOLID
-1,2
SPHERICAL SOLID
0.5FORVD<7
0.2FORVD>7
Fig. 6 Force Coefficients for Solid Shapes Mounted on a Surface
5 The wake shed from an upstream body may intensify
motions in the direction of the wind, and may also effect
crosswind motions.
6 The designer must be aware of the following three
forms of wind induced motion which are characterized
by increasing amplitude of oscillation with increase of
wind speed.
a) Galloping — Galloping is transverse oscillations
of some structures due to the development of
aerodynamic forces which are in phase with the
motion. It is characterized by the progressively
increasing amplitude of transverse vibration with
increase of wind speed. The cross-sections which
are particularly prone to this type of excitation
include the following:
i) Ail structures with non-circular cross-
sections, such as triangular, square, polygons,
as well as angles, crosses and T-sections.
ii) Twisted cables and cables with ice
encrustations.
b) Flutter — Flutter is unstable oscillatory motion
of a structure due to coupling between
aerodynamic force and the elastic deformation of
the structure. Perhaps the most common form is
the oscillatory motion due to combined bending
and torsion. Although oscillatory motions in each
degree of freedom may be dampled, instability
can set in due to energy transfer from one mode
of oscillation to another, and the structure is seen
to execute sustained or divergent oscillations with
a type of motion which is a combination of the
individual modes of motion. Such energy transfer
takes place when the natural frequencies of the
modes, taken individually, are close to each other
(ratio being typically less than 2.0). Flutter can
set in at wind speeds much less than those required
for exciting the individual modes of motion. Long
span suspension bridge decks or any member of a
structure with large values of dlt (where d is the
depth of a structure or structural member parallel
to wind stream and t is the least lateral dimension
50
NATIONAL BUILDING CODE OF INDIA
of a member) are prone to low speed flutter. Wind
tunnel testing is required to determine critical
flutter speeds and the likely structural response.
Other types of flutter are single degree of freedom
stall flutter, torsional flutter etc.
c) Ovatling — Thin walled structures with open ends
at one or both ends, such as oil storage tanks, and
natural draught cooling towers, in which the ratio
of the diameter of minimum lateral dimension to
the wall thickness is of the order of 100 or
more, are prone to ovalling oscillations. These
oscillations are characterized by periodic radial
deformation of the hollow structure.
7 Buildings and structures that may be subjected to
serious wind excited oscillations require careful
investigation. It is to be noted that wind induced
oscillations may occur at wind speeds lower than the
static design wind speed for the location.
8 Analytical methods for determining dynamic
response of structures to wind loading can be found in
the following publications:
a) Engineering Science Data, Wind Engineering sub-
series (4 volumes), London, ESDU International.
b) 'Wind Engineering in the Eighties'. Construction
Industry Research and Information Association,
1981, London.
c) 'Wind Effects on Structures' by E Simiu and
R.H. Scanlan. Johan Wiley and Sons, New York,
1978.
d) Supplement to the National Building Code of
Canada, 1980. NRCC, No. 17724. National
Research Council of Canada, Ottawa, 1980.
e) Wind Forces on Structures by Peter Sachs.
Pergamon Press.
f) Flow Induced Vibration by Robert D. Clevins.
Von Nostrand Reinfold Co.
9 In assessing wind loads due to such dynamic
phenomenon as galloping, flutter and ovalling, if the
required information is not available either in the
references of Note 8 or other literature, specialist advice
shall be sought, including experiments on models in
wind tunnels.
4.6.2 Motions Due to Vortex Shedding
4.6.2.1 Slender structures — For a structure, the
shedding frequency, r| shall be determined by the
following formula;
„- sv <
where
a)
S = Strouhal number,
V d = design wind velocity, and
b - The breadth of a structure or structural
members in the horizontal plane normal
to the wind direction.
Circular Structures — For structures circular
in cross-section:
S = 0.20 for bV z not greater than 7, and
S = 0.25 for bV z greater than 7.
b) Rectangular Structures — For structures of
rectangular cross-section:
S = 0.15 for all values of bV z .
NOTES
1 Significant cross wind motions may be produced by
vortex shedding if the natural frequency of the structure
or structural element is equal to the frequency of the
vortex shedding within the range of expected wind
velocities. In such cases, further analysis should be
carried out on the basis of references given in Note 8
of 4.6.1.
2 Unlined welded steel chimney stacks and similar
structures are prone to excitation by vortex shedding.
3 Intensification of the effects of periodic vortex
shedding has been reported in cases where two or more
similar structures are located in close proximity, for
example, at less than 20 b apart, where b is the
dimension of the structure normal to the wind.
4 The formulae given in 4.6.2.1 (a) and 4.6.2.1 (b) are
valid for infinitely long cylindrical structures. The value
of S decreases slowly as the ratio of length to maximum
transverse width decreases; the reduction being up to
about half the value, if the structure is only three times
higher than its width. Vortex shedding need not be
considered if the ratio of length to maximum transverse
width is less than 2.0.
4.7 Gust Factor (GF) or Gust Effectiveness Factor
(GEF) Method
4.7.1 Application
Only the method of calculating load along wind or drag
load by using gust factor method is given in the section
since methods for calculating load across-wind or other
components are not fully matured for all types of
structures. However, it is permissible for a designer to
use gust factor method to calculate all components of
load on a structure using any available theory.
However, such a theory must take into account the
random nature of atmospheric wind speed.
NOTE — It may be noted that investigations for various types
of wind induced oscillations out lined in 4.6 are in no way
related to the use of gust factor method given in 4.7. Although
study of 4.6 is needed for using gust factor method.
4.7.2 Hourly Mean Wind
Use of the existing theories of gust factor method
require a knowledge of the maximum of the wind
speeds averaged over one hour at a particular site.
Hourly mean wind speeds at different heights over
different terrains is given in Table 28.
NOTE — It must also be recognized that the ratio of hourly
mean wind (HMW) to peak gust (PG) given in Table 28 may
not be obtainable in India since extreme wind occurs mainly
due to cyclones and thunderstorms, unlike in UK and Canada
where the mechanism is fully developed pressure system.
However Table 28 may be followed at present for the estimation
of the hourly mean wind speed till more reliable values become
available.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
51
Table 28 Hourly Mean Wind Speed Factor k 2 in
Different Terrains for Different Heights
(Clause 4.1 2)
Height
Terrain
m
Category 1
Category 2
Category 3
Category 4
(I)
(2)
(3)
(4)
(5)
10
0.78
0.67
0.50
0.24
15
0.82
0.72
0.55
0.24
20
0,85
0.75
0.59
0,24
30
0.88
0.79
0.64
0.34
50
0.93
0.85
0.70
0.45
100
0.99
0.92
0.79
0.57
150
1.03
0.96
0,84
0,64
200
1.06
1.00
0.88
0.68
250
1.08
1.02
0.91
0.72
300
1.09
1.04
0.93
0.74
350
1.11
1.06
0.95
0.77
400
1.12
1.07
0.97
0.79
450
1.13
1.08
0.98
0.81
500
1.14
1.09
0.99
0.82
4.7*2,1 Variation of hourly mean wind speed with height
The variation of hourly mean wind speed with height
shall be calculated as follows:
'z ~ 'b' v 1* v 2* v 3
where
V y = hourly mean wind speed in m/s at height z,
V h = regional basic wind speed in m/s (see Fig. 1 ),
k l - probability factor (Table 4),
k 2 = terrain and height factor (Table 28), and
k^ - topography factor (4.4.3.3).
4.7.3 Along Wind Load
Along wind load on a structure on a strip area (A e ) at
any height (Z) is given by:
F z =C f A e p z G
where
b\ = along wind load on the structure at any
height Z corresponding to strip area A ,
C f = force coefficient for the building,
A = effective frontal area considered for the
e
structure at height Z.
p 7 = design pressure at height Z due to mean
hourly wind obtained as 0.6 V 2 , (N/m 2 ), and
_ r peak load , . .
O = gust lactor — - and is given by:
mean load
G = l + * f r 4
fl(l + 0) 2 + —
P.
where
g f = peak factor defined as the ratio of the
expected peak value to the root mean value
of a fluctuating load, and
r = a roughness factor which is dependent on
the size of the structure in relation, to the
ground roughness.
The value of 'g f r is given in Fig. 7.
50 100 200
BUILDING HEIGHT, m
Fig. 7 Values of g { r and L h
500
52
NATIONAL BUILDING CODE OF INDIA
Table 28 Hourly Mean Wind Speed Factor k 2 in
Different Terrains for Different Heights
(Clause 4.7.2)
Height
Terrain
m
Category 1
Category 2
Category 3
Category 4
(1)
(2)
(3)
(4)
(5)
10
0.78
0.67
0.50
0.24
15
0.82
0.72
0.55
0.24
20
0.85
0.75
0.59
0.24
30
0.88
0.79
0.64
0.34
50
0.93
0.85
0.70
0.45
100
0.99
0.92
0.79
0.57
150
1.03
0.96
0.84
0.64
200
1.06
1.00
0.88
0.68
250
1.08
1.02
0.91
0.72
300
1.09
1.04
0.93
0.74
350
1.11
1.06
0.95
0.77
400
1.12
1.07
0.97
0.79
450
1.13
1.08
0.98
0.81
500
1.14
1.09
0.99
0.82
k 3 = topography factor (4.4.3.3).
4.7.3 Along Wind Load
Along wind load on a structure on a strip area (A e ) at
any height (Z) is given by:
F z =C t \p z G
where
F z = along wind load on the structure at any
height Z corresponding to strip area A e ,
C f = force coefficient for the building,
A e = effective frontal area considered for the
structure at height Z.
p z = design pressure at height Z due to mean
hourly wind obtained as 0.6 V 2 z (N/m 2 ), and
G = gust factor— — - and is given by:
mean load
4.7.2. 1 Variation of hourly mean wind speed with height
The variation of hourly mean wind speed with height
shall be calculated as follows:
where
V z - hourly mean wind speed in m/s at height z,
V h = regional basic wind speed in m/s (see Fig. 1 ),
k x = probability factor (Table 4),
k 2 = terrain and height factor (Table 28), and
G = l + g f r A
Z?(l + 0) 2 + —
where
g { = peak factor defined as the ratio of the
expected peak value to the root mean value
of a fluctuating load, and
r - a roughness factor which is dependent on
the size of the structure in relation to the
ground roughness.
The value of 'g f f is given in Fig. 7.
1250 ^
100 200
BUILDING HEIGHT, m
Fig. 7 Values of g ( r and L h
52
NATIONAL BUILDING CODE OF INDIA
B is a background factor indicating a measure of
the slowly varying component of the fluctuating
wind load and is obtained from Fig. 8.
SE
~jT is a measure of the resonant component of the
fluctuating wind load.
E is a measure of the available energy in the wind
stream at the natural frequency of the structure
(see Fig. 9).
S is size reduction factor (see Fig, 10).
(3 is the damping coefficient (as a fraction of critical
damping) of the structure (see Table 29).
5 SEISMIC LOAD
5.0 This clause deals with assessment of seismic loads
on various structures and earthquake resistant design
of buildings. (For the purpose of this clause the symbols
given at Annex G are applicable).
5.1 Terminology for Earthquake Engineering
5.1.1 For the purpose of this standard, the following
definitions shall apply which are applicable generally
to all structures:
NOTE — For the definitions of terms pertaining to soil
mechanics and soil dynamics references may be made to Part 6
'Structural Design, Section 2 Soils and Foundations'.
and is to be accounted only for buildings 512 Closely-Spaced Modes
less than 75 m high in terrain category 4 and for
buildings less than 25 high in terrain category 3,
and is to be taken as zero in ail other cases.
In Fig. 8 and 10,
A^andf = W
C z h '° V h
where
C. = lateral correlation constant which may be taken
as 10 in the absence of more precise load data;
C z = longitudinal correlation constant which may
be taken as J 2 in the absence of more precise
load data;
b = breadth of a structure normal to the wind
stream;
h - height of a structure;
V y - hourly mean wind speed at height Z;
f o = natural frequency of the structure in the
fundamental mode; and
L f = a measure of turbulence length scale (see Fig. 7)
Table 29 Suggested Values of Damping
Coefficient
(Clause 4.7.3)
Nature of Structure
(1)
Damping Coefficient, j
(2)
Welded steel structures
Bolted steel structures
Reinforced concrete structures
0.010
0.020
0.016
The peak acceleration along the wind direction at the
top of the structure is given by the following formula:
a = (2nf ) x g t r —
where
x = mean deflection at the position where the
acceleration is required.
Closely-spaced modes of a structure are those of its
natural modes of vibration whose natural frequencies
differ from each other by 10 percent or less of the lower
frequency.
5.1.3 Critical Damping
The damping beyond which the free vibration motion
will not be oscillatory.
5.1.4 Damping
The effect of internal friction, imperfect elasticity of
material, slipping, sliding etc, in reducing the amplitude
of vibration and is expressed as a percentage of critical
damping.
5.1.5 Design Acceleration Spectrum
Design acceleration spectrum refers to an average
smoothened plot of maximum acceleration as a
function of frequency or time period of vibration for a
specified damping ratio for earthquake excitations at
the base of a single degree of freedom system.
5.1.6 Design Basis Earthquake (DBE)
It is the earthquake which can reasonably be expected
to occur at least once during the design life of the
structure.
5.1.7 Design Horizontal Acceleration Coefficient (A h )
It is a horizontal acceleration coefficient that shall be
used for design of structures.
5.1.8 Design Lateral Force
It is the horizontal seismic force prescribed by this
standard, that shall be used to design a structure.
5.1.9 Ductility
Ductility of a structure, or its members, is the capacity
to undergo large inelastic deformations without
significant loss of strength or stiffness.
PART 6 STRUCTURAL DESIGN — SECTION I LOADS, FORCES AND EFFECTS
53
CO
of
e
o
Q
2
3
2
CD
O
<
CO
0.8
0.6
0.4
0.3
0.2
0.1
0.08
0.06
0.04
0.02
r0
^-0.1
.0.2
f
A = 10
5^
1 ""
^ 2 ^T V
s^OS
^$
^ Vs >^*^ v
^
^
s
^
$
A ~Czh
\
x
N
^
>^
K|
.01 .02 .04 .06
.1 .2 .3 .4 .5 .8 1
C z h/L h
Fig. 8 Background Factor, B
4 6 8 10
0.4
0.3
uj 0.2
g 0.15
i-
Q
£ 0.1
* 0.05
g 0.04
UJ
k 0.03
O 0.02
0.01
6 8 10 20 30 40 60 80 100 200 300 600
Fig. 9 Gust Energy Factor, E
54
NATIONAL BUILDING CODE OF INDIA
-Vh »-i
it
Vz
/ J
i
h
/ Z
i
f
ii
v//y///////////////.
Vh
CO
of
o
I-
o
<
O
D
a:
UJ
N
CO
08-
n 5-
n a -
X
n ^ -
X
^ ^ s
V\
u.z
n 1^-
U. IO
n 1-
U. I
0.08-
n n^-
u.uo
n ha -
U.U*T
U.Uo
n no -
u.uz
U.UO
01-
A
10
5
2 1
.5
0.
2C
1.1
n nnft-i
\
u.uuo ^
005-
Oyb
Czh
\
n nn>i -
A
N
U.UU4
\
U.UUo
U.UUZ
CM Tf CD
odd
o o p
T^ CSI «fr
q
CD
o o
t= CM
o o g
-^ CD O
o o
o o
CM «fr
o
o
CD
REDUCED FREQUENCY, F = Slh*L
V h
Fig. 10 Size Reduction Factor, 5
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
55
5.1.10 Epicentre
The geographical point on the surface of earth
vertically above the focus of the earthquake.
5.1.11 Effective Peak Ground Acceleration (EPGA)
It is 0.4 times the 5 percent damped average spectral
acceleration between period 0.1 to 0.3 s. This shall be
taken as zero period acceleration (ZPA).
5.1.12 Floor Response Spectra
Floor response spectra is the response spectra for a
time history motion of a floor. This floor motion time
history is obtained by an analysis of multi-storey
building for appropriate material damping values
subjected to a specified earthquake motion at the base
of structure.
5.1.13 Focus
The originating earthquake source of the elastic waves
inside the earth which cause shaking of ground due to
earthquake.
5.1.14 Importance Factor (I)
It is a factor used to obtain the design seismic force
depending on the functional use of the structure,
characterised by hazardous consequences of its failure,
its post-earthquake functional need, historic value, or
economic importance.
5.1.15 Intensity of Earthquake
The intensity of an earthquake at a place is a measure
of the strength of shaking during the earthquake, and
is indicated by a number according to the modified
Mercalli Scale or M.S.K. scale of Seismic Intensities
(see Annex H).
5.1.16 Liquefaction
Liquefaction is a state in saturated cohesionless soil
wherein the effective shear strength is reduced to
negligible value for all engineering purpose due to pore
pressure caused by vibrations during an earthquake
when they approach the total confining pressure. In
this condition the soil tends to behave like a fluid mass.
5.1.17 Lithological Features
The nature of the geological formation of the earth's
crust above bed rock on the basis of such characteristics
as colour, structure, mineralogical composition and
grain size.
5.1.18 Magnitude of Earthquake (Richter' s Magnitude)
The magnitude of earthquake is a number, which is a
measure of energy released in an earthquake. It is
defined as logarithm to the base 10 of the maximum
trace amplitude, expressed in microns, which the
standard short-period torsion seismometer (with a
period of 0.8 s, magnification 2 800 and damping
nearly critical) would register due to the earthquake at
an epicentral distance of 100 km.
5.1.19 Maximum Considered Earthquake (MCE)
The most severe earthquake effects considered by this
Code.
5.1.20 Modal Mass (MJ
Modal mass of a structure subjected to horizontal or
vertical, as the case may be, ground motion is a part of
the total seismic mass of the structure that is effective
in mode k of vibration. The modal mass for a given
mode has a unique value irrespective of scaling of the
mode shape.
5.1.21 Modal Participation Factor (P k )
Modal participation factor of mode k of vibration is
the amount by which mode k contributes to the overall
vibration of the structure under horizontal and vertical
earthquake ground motions. Since the amplitudes of
95 per cent mode shapes can be scaled arbitrarily, the
value of this factor depends on the scaling used for
mode shapes.
5.1.22 Modes of Vibration (see 5.1.25)
5.1.23 Mode Shape Coefficient ((j>- ± )
When a system is vibrating in normal mode k, at any
particular instant of time, the amplitude of mass i
expressed as a ratio of the amplitude of one of the
masses of the system, is known as mode shape
coefficient (0 ik ).
5.1.24 Natural Period (T)
Natural period of a structure is its time period of
undamped free vibration.
5.1.24.1 Fundamental natural period (T x )
It is the first (longest) modal time period of vibration.
5.1.24.2 Modal natural period (T k )
The modal natural period of mode k is the time period
of vibration in mode k
5.1.25 Normal Mode
A system is said to be vibrating in a normal mode when
all its masses attain maximum values of displacements
and rotations simultaneously, and pass through
equilibrium positions simultaneously.
5.1.26 Response Reduction Factor (R)
It is the factor by which the actual base shear force,
that would be generated if the structure were to remain
elastic during its response to the design basis
56
NATIONAL BUILDING CODE OF INDIA
earthquake (DBE) shaking, shall be reduced to obtain
the design lateral force.
5.1.27 Response Spectrum
The representation of the maximum response of
idealized single degree freedom systems having certain
period and damping, during earthquake ground motion.
The maximum response is plotted against the
undamped natural period and for various damping
values, and can be expressed in terms of maximum
absolute acceleration, maximum relative velocity, or
maximum relative displacement.
5.1.28 Seismic Mass
It is the seismic weight divided by acceleration due to
gravity.
5.1.29 Seismic Weight (W)
It is the total dead load plus appropriate amounts of
specified imposed load.
5.1.30 Structural Response Factors (SJg)
It is a factor denoting the acceleration response
spectrum of the structure subjected to earthquake
ground vibrations, and depends on natural period of
vibration and damping of the structure.
5.1.31 Tectonic Features
The nature of geological formation of the bed rock in
the earth's crust revealing regions characterized by
structural features, such as dislocation, distortion,
faults, folding, thrusts, volcanoes with their age of
formation, which are directly involved in the earth
movement or quake resulting in the above
consequences.
5.1.32 Time History Analysis
It is an analysis of the dynamic response of the structure
attach increment of time, when its base is subjected to
a specific ground motion time history.
5.1.33 Zone Factor (Z)
It is a factor to obtain the design spectrum depending
on the perceived maximum seismic risk characterized
by maximum considered earthquake (MCE) in the zone
in which the structure is located. The basic zone factors
included in this standard are reasonable estimate of
effective peak ground acceleration.
5.1.34 Zero Period Acceleration (ZPA)
It is the value of acceleration response spectrum for
period below 0.03 s (frequencies above 33 Hz).
5.2 Terminology for Earthquake Engineering of
Buildings
5.2.1 For the purpose of earthquake resistant design
of buildings in this standard, the following definitions
shall apply:
5.2.2 Base
It is the level at which inertia forces generated in the
structure are transferred to the foundation, which then
transfers these forces to the ground.
5.2.3 Base Dimensions (d)
Base dimension of the building along a direction is
the dimension at its base, in metres, along that
direction.
5.2.4 Centre of Mass
The point through which the resultant of the masses of
a system acts. This point corresponds to the centre of
gravity of masses of system.
5.2.5 Centre of Stiffness
The point through which the resultant of the restoring
forces of a system acts.
5.2.6 Design Eccentricity (e^)
It is the value of eccentricity to be used at floor i in
torsion calculations for design.
5.2.7 Design Seismic Base Shear (V B )
It is the total design lateral force at the base of a
structure.
5.2.8 Diaphragm
It is a horizontal, or nearly horizontal system, which
transmits lateral forces to the vertical resisting
elements, for example, reinforced concrete floors and
horizontal bracing systems.
5.2.9 Dual System
Buildings with dual system consist of shear walls (or
braced frames) and moment resisting frames such
that:
a) the two systems are designed to resist the total
design lateral force in proportion to their
lateral stiffness considering the interaction of
the dual system at all floor levels; and
b) the moment resisting frames are designed to
independently resist at least 25 percent of the
design base shear.
5.2.10 Height of Floor (h { )
It is the difference in levels between the base of the
building and that of floor /.
5.2.11 Height of Structure (h)
It is the difference in levels, in metres, between its base
and its highest level.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
57
5.2.12 Horizontal Bracing System
It is a horizontal truss system that serves the same
function as a diaphragm.
5.2.13 Joint
It is the portion of the column that is common to other
members, for example, beams, framing into it.
5.2.14 Lateral Force Resisting Element
It is part of the structural system assigned to resist
lateral forces.
5.2.15 Moment-Resisting Frame
It is a frame in which members and joints are capable
of resisting forces primarily by flexure.
5.2.15.1 Ordinary moment-resisting frame
It is a moment-resisting frame not meeting special
detailing requirements for ductile behaviour.
5.2.15.2 Special moment-resisting frame
It is a moment-resisting frame specially detailed to
provide ductile behaviour and comply with the
requirements given in IS 4326 or IS 13920 or
SP 6(6).
5.2.16 Number of Storeys (n)
Number of storeys of a building is the number of levels
above the base. This excludes the basement storeys,
where basement walls are connected with the ground
floor deck or fitted between the building columns. But,
it includes the basement storeys, when they are not so
connected.
5.2.17 Principal Axes
Principal axes of a building are generally two
mutually perpendicular horizontal directions in plan
of a building along which the geometry of the building
is oriented.
5.2.18 P-A Effect
It is the secondary effect on shears and moments of
frame members due to action of the vertical loads,
interacting with the lateral displacement of building
resulting from seismic forces.
5.2.19 Shear Wall
It is a wall designed to resist lateral forces acting in its
own plane.
5.2.20 Soft Storey
It is one in which the lateral stiffness is less than 70
percent of that in the storey above or less than 80
percent of the average lateral stiffness of the three
storeys above.
5.2.21 Static Eccentricity (e si )
It is the distance between centre of mass and centre of
rigidity of floor /.
5.2.22 Storey
It is the space between two adjacent floors.
5.2.23 Storey Drift
It is the displacement of one level relative to the other
level above or below.
5.2.24 Storey Shear (V.J
It is the sum of design lateral forces at all levels above
the storey under consideration.
5.2.25 Weak Storey
It is one in which the storey lateral strength is less than
80 percent of that in the storey above. The storey lateral
strength is the total strength of all seismic force resisting
elements sharing the storey shear in the considered
direction.
5.3 General Principles and Design Criteria
5.3.1 General Principles
5.3.1.1 Ground motion
The characteristics (intensity, duration, etc) of seismic
ground vibrations expected at any location depends
upon the magnitude of earthquake, its depth of focus,
distance from the epicentre, characteristics of the path
through which the seismic waves travel, and the soil
strata on which the structure stands. The random
earthquake ground motions, which cause the structure
to vibrate, can be resolved in any three mutually
perpendicular directions. The predominant direction
of ground vibration is usually horizontal.
Earthquake-generated vertical inertia forces are to be
considered in design unless checked and proven by
specimen calculations to be not significant. Vertical
acceleration should be considered in structures with large
spans, those in which stability is a criterion for design,
or for overall stability analysis of structures. Reduction
in gravity force due to vertical component of ground
motions can be particularly detrimental in cases of
prestressed horizontal members and of cantilevered
members. Hence, special attention should be paid to the
effect of vertical component of the ground motion on
prestressed or cantilevered beams, girders and slabs.
5.3.1.2 The response of a structure to ground
vibrations is a function of the nature of foundation soil,
materials, form, size and mode of construction of
structures; and the duration and characteristics of
ground motion. This standard specifies design forces
for structures standing on rocks or soils which do not
58
NATIONAL BUILDING CODE OF INDIA
settle, liquefy or slide due to loss of strength during
ground vibrations.
5.3.1.3 The design approach adopted in this standard
is to ensure that structures possess at least a minimum
strength to withstand minor earthquakes (<DBE),
which occur frequently, without damage; resist
moderate earthquakes (DBE) without significant
structural damage though some non-structural damage
!may occur; and aims that structures withstand a major
earthquake (MCE) without collapse. Actual forces that
appear on structures during earthquakes are much
greater than the design forces specified in this Code.
However, ductility, arising from inelastic material
ibehaviour and detailing, and overstrength, arising from
|the additional reserve strength in structures over and
above the design strength, are relied upon to account
for this difference in actual and design lateral loads.
Reinforced and prestressed concrete members shall be
suitably designed to ensure that premature failure due
to shear or bond does not occur, subject to the
provisions of Part 6 'Structural Design, Section 5
Concrete'. Provisions for appropriate ductile detailing
of reinforced concrete members shall be in accordance
with good practice [6-1(4)].
In steel structures, members and their connections
should be so proportioned that high ductility is
obtained, vide SP 6(6), avoiding premature failure due
to elastic or inelastic buckling of any type.
The specified earthquake loads are based upon post-
elastic energy dissipation in the structure and because
of this fact, the provision of this Code for design,
detailing and construction shall be satisfied even for
structures and members for which load combinations
that do not contain the earthquake effect indicate larger
demands than combinations including earthquake.
5.3.1.4 Soil-structure interaction
The soil-structure interaction refers to the effects of
the supporting foundation medium on the motion of
structure. The soil-structure interaction may not be
considered in the seismic analysis for structures
supported on rock or rock-like material.
5.3.1.5 The design lateral force specified in this Code
shall be considered in each of the two orthogonal
horizontal directions of the structure. For structures
which have lateral force resisting elements in the two
orthogonal directions only, the design lateral force shall
be considered along one direction at a time, and not in
both directions simultaneously. Structures, having
lateral force resisting elements (for example, frames,
shear walls) in directions other than the two orthogonal
directions, shall be analysed considering the load
combinations specified in 5.3.3.2.
Where both horizontal and vertical seismic forces are
taken into account, load combinations specified
in 5.3.3.3 shall be considered.
5.3.1.6 Equipment and other systems, which are
supported at various floor levels of the structure, will
be subjected to motions corresponding to vibration at
their support points. In important cases, it may be
necessary to obtain floor response spectra for design
of equipment supports. For detail reference be made
to good practice [6-1(5)]
5.3.1.7 Additions to existing structures
Additions shall be made to existing structures only as
follows:
a) An addition that is structurally independent
from an existing structures shall be designed
and constructed in accordance with the
seismic requirements for new structures.
b) An addition that is not structurally independent
from an existing structure shall be designed
and constructed such that the entire structure
conforms to the seismic force resistance
requirements for new structures unless the
following three conditions are complied with:
1) The addition shall comply with the
requirements for new structures;
2) The addition shall not increase the
seismic forces in any structural elements
of the existing structure by more than
5 per cent unless the capacity of the
element subject to the increased force is
still in compliance with this standard; and
3) The addition shall not decrease the
seismic resistance of any structural
element of the existing structure unless
reduced resistance is equal to or greater
than that required for new structures.
5.3.1.8 Change in occupancy
When a change of occupancy results in a structure
being reclassified to a higher importance factor (/), the
structure shall conform to the seismic requirements for
a new structure with the higher importance factor.
5.3.2 Assumptions
The following assumptions shall be made in the
earthquake-resistant design of structures:
a) Earthquake causes impulsive ground motions,
which are complex and irregular in character,
changing in period and amplitude each lasting
for a small duration. Therefore, resonance of
the type as visualized under steady-state
sinusoidal excitations, will not occur as it
would need time to build up such amplitudes.
NOTE — However, there are exceptions where
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
59
resonance-like conditions have been seen to occur
between long distance waves and tall structures founded
on deep soft soils.
b) Earthquake is not likely to occur simultaneously
with wind or maximum flood or maximum
sea waves.
c) The value of elastic modulus of materials,
wherever required, may be taken as for static
analysis unless a more definite value is
available for use in such condition (see Part 6
'Structural Design, Section 5 Concrete and
Section 6 Steel'.
5.3.3 Load Combination and Increase in Permissible
Stresses
5.3.3.1 Load combinations
When earthquake forces are considered on a structure,
these shall be combined as per 5.3.3.1.1 and 5.3.3.1.2
where the terms DL, IL and EL stand for the response
quantities due to dead load, imposed and designated
earthquake load respectively.
5.3.3.1.1 Load factors for plastic design of steel
structures
In the plastic design of steel structures, the following
load combinations shall be accounted for:
a) 1.7 (DL + IL)
b) 1.7 (DL±EL)
c) 1.3 (DL+IL±EL)
5.3.3.1.2 Partial safety factors for limit state design of
reinforced concrete and prestressed concrete structures
In the limit state design of reinforced and prestressed
concrete structures, the following load combinations
shall be accounted for:
a) 1.5 (DL + IL)
b) 1.2 (DL+IL±EL)
c) 1.5 (DL±EL)
d) 0.9 DL± 1.5 EL
5.3.3.2 Design horizontal earthquake load
5.3.3.2.1 When the lateral load resisting elements are
oriented along orthogonal horizontal direction, the
structure shall be designed for the effects due to full design
earthquake load in one horizontal direction at time.
5.3.3.2.2 When the lateral load resisting elements are
not oriented along the orthogonal horizontal directions,
the structure shall be designed for the effects due to
full design earthquake load in one horizontal direction
plus 30 percent of the design earthquake load in the
other direction.
NOTE — For instance, the building should be designed for
(± £L ± 03 EL y ) as well as (± 0.3 EL x ± EL y ), where x and y are
two orthogonal horizontal direction, EL in 5.3.3.1.1 and 5.3.3.1.2
shall be replaced by (£L ± 0.3 EL y ) or (EL y ± 0.3 £L ).
5.3.3.3 Design vertical earthquake load
When effects due to vertical earthquake loads are to
be considered, the design vertical force shall be
calculated in accordance with 5.3.4.5.
5.3.3.4 Combination for two or three component motion
5.3.3.4.1 When responses from the three earthquake
components are to be considered, the responses due
to each components may be combined using the
assumption that when the maximum response from one
component occurs, the responses from the other two
component are 30 percent of their maximum. All
possible combinations of the three components (£L x ,
EL and EL x ) including variations in sign (plus or minus)
shall be considered. Thus, the response due earthquake
force (EL) is the maximum of the following three cases:
a) ±EL x ±0.3 EL Y ± 03 EL z
b) ±EL ±03 EL ±03 EL
/ y x z
c) ±EL ±03 EL ±03 EL
' z x y
Where x and y are two orthogonal directions and z is
vertical direction.
5.3.3.4.2 As an alternative to the procedure in 533.4.1,
the response (EL) due to the combined effect of the
three components can be obtained on the basis of
'square root of the sum of the square (SRSS)' that is
EL = ^(ELS+(EL y ) 1 +(EL L f
NOTE — The combination procedure of 5.3.3.4.1 and 5.3.3.4.2
apply to the same response quantity (say, moment in a column
about its major axis, or storey shear in a frame) due to different
components of the ground motion.
5.3.3.4.3 When two component motions (say one
horizontal and one vertical, or only two horizontal)
are combined, the equations in 5.3.3.4.1 and 5.3.3.4.2
should be modified by deleting the term representing
the response due to the component of motion not being
considered.
5.33.5 Increase in permissible stresses
533.5.1 Increase in permissible stresses in materials
When earthquake forces are considered along with other
normal design forces, the permissible stresses in material,
in the elastic method of design, may be increased by one-
third. However, for steels having a definite yield stress,
the stress be limited to the yield stress; for steels without
a definite yield point, the stress will be limited to 80
percent of the ultimate strength or 0.2 percent proof stress,
whichever is smaller; and that in prestressed concrete
members, the tensile stress in the extreme fibres of the
concrete may be permitted so as not to exceed two-thirds
of the modulus of rupture of concrete.
60
NATIONAL BUILDING CODE OF INDIA
5.3.3.5.2 Increase in allowable pressure in soils
When earthquake forces are included, the allowable
bearing pressure in soils shall be increased as per
Table 1, depending upon type of foundation of the
structure and the type of soil.
In soil deposits consisting of submerged loose
sands and soils falling under classification SP with
standard penetration N values less than 15 in seismic
Zones III, IV, V and less than 10 in seismic Zone II,
the vibration caused by earthquake may cause
liquefaction or excessive total and differential
settlements. Such sites should preferably be avoided
while locating new settlements or important projects.
Otherwise, this aspect of the problem needs to be
investigated and appropriate methods of compaction
or stabilization adopted to achieve suitable N values
as indicated in Note 3 under Table 30. Alternatively,
deep pile foundation may be provided and taken to
depths well into the layer which is not likely to
liquefy. Marine clays and other sensitive clays are
also known to liquefy due to collapse of soil structure
and will need special treatment according to site
condition.
NOTE — Specialist literature may be referred for determining
liquefaction potential of a site.
Table 30 Percentage of Permissible Increase in Allowable Bearing
Pressure or Resistance of Soils
{Clause 5.3.3.5.2)
SI
No.
Foundation
Type of Soil Mainly Constituting the Foundation
(1)
(2)
Type I Rock or Hard Soil:
Well graded gravel and sand
gravel mixtures with or without
clay binder, and clayey sands
poorly graded or sand clay
mixtures (GB, CW, SB, SW and
SC) J) having 2) above 30, where N
is the standard penetration value
(3)
Type II Medium Soils
All soils with N between
10 an 30, and poorly
graded sands or gravelly
sands with little or no
fines (SP 1 -) with N > 15
(4)
Type m Soft Soils: All
soils other than SP 1 *
withAr<10
(5)
i) Piles passing through any soil but
resting on solid type I
ii) Piles not covered under item (i)
iii) Raft foundations
iv) Combined isolated RCC footing with
tie beams
v) Isolated RCC footing without tie beams,
or unreinforced strip foundations
vi) Well foundations
50
50
50
50
50
50
25
50
25
25
25
50
25
50
25
NOTES
1 The allowable bearing pressure shall be determined in accordance with good practice [6-1(6)].
2 If any increase in bearing pressure has already been permitted for forces other than seismic forces, the total increase in allowable
bearing pressure when seismic force is also included shall not exceed the limits specified above.
3 Desirable minimum field values of N — If soils of smaller W-values are met, compacting may be, adopted to achieve these values or
deep pile foundations going to stronger strata should be used.
4 The values of TV (corrected values) are at the founding level and the allowable bearing pressure shall be determined in accordance
with good practice [6-1(6)].
Seismic Zone Level
m
Depth Below Ground N-Values
III, IV and V
II (for important structures only)
< 5
>10
< 5
>10
15
25
15
20
Remark
For values of depths between 5 m
and 10 m, linear interpolation is
recommended.
5 The piles should be designed for lateral loads neglecting lateral resistance of soil layers liable to liquefy.
6 Accepted standard [6-1(7)] and good practice [6-1(8)] may also be referred.
7 Isolated R.C.C. footing without tie beams, or unreinforced strip foundation shall not be permitted in soft soils with N<10.
See accepted standard [6-1(7)].
' See good practice [6-1(8)].
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
61
5.3.4 Design Spectrum
5.3.4.1 For the purpose of determining seismic forces,
the country is classified into four seismic zones as
shown in Fig. 11.
5.3.4.2 The design horizontal seismic coefficient A h
for a structure shall be determined by the following
expression:
_ 71 S. x
A= 2R g
Provided that for any structure with T> 0.1 sec, the
value of A h will not be less than Z/2 whatever be the
value of///?
where
Z - Zone factor given in Table 31, is for the
maximum considered earthquake (MCE)
and service life of structure in a zone. The
factor 2 in the denominator of > is used so
as to reduce the maximum considered
earthquake (MCE) zone factor to the factor
for design basis earthquake (DBE).
Zone factor for some important towns are
given at Annex J.
/ = Importance factor, depending upon the
functional use of the structures, characterised
by hazardous consequences of its failure,
post-earthquake functional needs, historical
value, or economic importance (Table 35).
R - Response reduction factor, depending on
the perceived seismic damage performance
of the structure, characterized by ductile
or brittle deformations. However, the
ratio (///?) shall not be greater than 1.0
(Table 36). The values of R for buildings
are given in Table 36.
S/g - Average response acceleration coefficient
for rock or soil sites as given by Fig. 1 2 and
Table 32 based on appropriate natural
periods and damping of the structure. These
curves represent free field ground motion.
NOTE — For various types of structures, the values
of Importance Factor /, Response Reduction Factor /?,
and damping values are given in the respective parts
of this standard. The method (empirical or otherwise)
to calculate the natural periods of the structure to be
adopted for evaluating S/g is also given in the
respective parts of this Code.
Table 31 Zone Factor, Z
(Clause 5.3.4.2)
Seismic Zone
II
III
IV
V
Seismic Intensity
Low
Moderate
Severe
Very Severe
Z
0.10
0.16
0.24
0.36
for dynamic analysis, the value of A h as defined
in 5.3.4.2 for each mode shall be determined using the
natural period of vibration of that mode.
5.3.4.4 For underground structures and foundations
at depths of 30 m or below, the design horizontal
acceleration spectrum value shall be taken as half the
value obtained from 5.3.4.2. For structures and
foundations placed between the ground level and 30 m
depth, the design horizontal acceleration spectrum
value shall be linearly interpolated between A h and
0.5 v4 h , where A h is as specified in 5.3.4.2.
5.3.4.5 The design acceleration spectrum for vertical
motions, when required, may be taken as two-thirds
of the design horizontal acceleration spectrum
specified in 5.3.4.2.
Figure 12 shows the proposed 5 percent spectra for
rocky and soils sites and Table 32 gives the multiplying
factors for obtaining spectral values for various other
dampings.
For Rocky, or hard soil sites
S { l + l5T >
-^=2.50
S [i.OO/T
For Medium soil sites
S fl + lSF;
^=2.50
8 [1.36/7
For Soft soil sites
S [1 + 157;
-^ = 2.50
S 1.67/7
0.00<7<0.10
0.10 < 7 < 0.40
0.40<7<4.00
0.00 < 7 < 0.10
0.10 < 7 < 0.55
0.55<7<4.00
0.00 <T< 0.10
0.10<7<0.67
0.67 <7< 4.00
Table 32 Multiplying Factors for Obtaining
Values tor Other Damping
(Clause 5.3.4.2)
Damping
2 5 7 10 15 20 25 30
percent
Factors 3.20
1.40 1.00 0.90 0.80 0.70 0.60 0.55 0.50
5.3.4.3 Where a number of modes are to be considered
62
5.3.4.6 In case design spectrum is specifically
prepared for a structure at a particular project site, the
same may be used for design at the discretion of the
project authorities.
5.4 Buildings
5.4.1 Regular and Irregular Configuration
To perform well in an earthquake, a building should
possess four main attributes, namely, simple and
regular configuration, and adequate lateral strength,
stiffness and ductility. Buildings having simple regular
in plan as well as in elevation, suffer much less damage
NATIONAL BUILDING CODE OF INDIA
r<&
:?
MAP OF INDIA
SHOWING
SEISMIC ZONES OF INDIA
Based upon Survey of India Outline Map printed in 1993
Tho territorial waters ol India extend into Hie sea to a distance of twelve nautical miles measured (rum the appropriate base line.
The boundary pf MeghaJaya shown on this map is as interpreted from ihe istorth-Easierri Areas (Reorganisation) Act, 1971 . but das yet to be verified.
Responsibility for correctness of internal details shown on the map rests with true publisher
The state boundaries between Uttaranchal & Uttar Pradesh. Bihar & Jharkhand and Chhatisgatb & Madhya Pradesh have not been verified by Governments concerned.
NOTE — Towns falling at the boundary of zones demarcation line between IwO zones shall be considered in higher zone
Fro, 1 1 seismic Zones
© Government of India Copyright, 2003
H
LLJ
O
Li_
U=
HI
Q
o
3.0
2.5 h
2.0
b^ 1.5
2 «
LU
o
3
CO
Q
LU
CO
0,0
1.0 |-
0.5
-TYPE I (ROCK, OR HARD SOIL)
-TYPE II (MEDIUM SOIL)
-TYPE!!! (SOFT SOIL)
0,0 0.5 1.0 1.5 2,0 2,5
PERIOD(S)
3,0
3.5
4.0
Fig. 12 Response Spectra for Rock and Soil Sight for 5 Percent Damping
than buildings with irregular configurations. A building
shall be considered as irregular for the purposes of this
standard, if at least one of the conditions given
in Tables 33 and 34 is applicable.
Table 33 Definitions of Irregular Buildings —
Plan Irregularities (Fig. 13)
(Clause 5.4,1)
Si No. Irregularity Type and Description
i) Torsion Irregularity
To be considered when floor diaphragms are rigid in their
own plan in relation to the vertical structural elements that
resist the lateral forces. Torsional irregularity to be
considered to exist when the maximum storey drift,
computed with design eccentricity, at one end of the
structures transverse to an axis is more than 1.2 times the
average of the storey drifts at the two ends of the structure.
ii) Re-entrant Corners
Plan configurations of a structure and its lateral force resisting
system contain re-entrant corners, where both projections of
the structure beyond the re-entrant corner are greater than 15
percent of its plan dimension in the given direction.
iii) Diaphragm Discontinuity
Diaphragms with abrupt discontinuities or variations in
stiffness, including those having cut-out or open areas greater
than 50 percent of the gross enclosed diaphragm area, or
changes in effective diaphragm stiffness of more than 50
percent from one storey to the next.
iv) Out- of- Plane Offsets
Discontinuities in a lateral force resistance path, such as out-
of-plane offsets of vertical elements.
v) Non-parallel Systems
The vertical elements resisting the lateral force are not
parallel to or symmetric about the major orthogonal axes or
the lateral force resisting elements.
Table 34 Definition of Irregular Buildings —
Vertical Irregularities (Fig. 14)
(Clause 5.4.1)
Si No. Irreguiarity Type and Description
i) a) Stiffness Irreguiarity — Soft Storey
A soft storey is one in which the lateral stiffness is less
than 70 percent of that in the storey above or less than
80 percent of the average lateral stiffness of the three storeys
above.
b) Stiffness Irregularity — Extreme Soft Storey
An extreme soft storey is one in which the lateral stiffness
is less than 60 percent of thai in the storey above or less
than 70 percent of the average stiffness of the three storeys
above. For example, buildings on STILTS will fall under
this category.
ii) Mass Irregularity
Mass irregularity shall be considered to exist where the
seismic weight of any storey is more than 200 percent of
that of its adjacent storeys. The irregularity need not be
considered in case of roofs.
iii) Vertical Geometric Irregularity
Vertical geometric irregularity shall be considered to exist
where the horizontal dimension of the lateral force resisting
system in any storey is more than 150 percent of that in its
adjacent storey.
iv) In-Plane Discontinuity in Vertical Elements Resisting
Lateral Force
An in-plane offset of the lateral force resisting elements
greater than the length of those elements.
v) Discontinuity in Capacity — Weak Strorey
A weak storey is one in which the storey lateral strength is
less than 80 percent of that in the storey above. The storey
lateral strength is the total strength of all seismic force
resisting elements sharing the storey shear in the considered
direction.
PART 6 STRUCTURAL DESIGN— SECTION 1 LOADS, FORCES AND EFFECTS
65
VERTICAL COMPONENTS OF
SEISMIC RESISTING SYSTEM
HEAVY
MASS
I A2
13 A TORSIONAL IRREGULARITY
A/L> 0.15 -0.20
|a/L> 0.15- 0.20 17
J i
A/L> 0.15 -0.20
T
-L1-
A1
Tl
Ml
T
13 B RE - ENTRANT CORNER
Fig. 1 3 Plan Irregularities — Continued
66
NATIONAL BUILDING CODE OF INDIA
MASS RESISTANCE ECENTRICITY
RIGID i
DIAPHRAGM |
^ !
\ "1
OPEjp>
<
/
FLEXIBLE
DIAPHRAGM
">'
/
VERTICAL COMPONENTS OF SEISMIC RESISTING
SYSTEM
X
FLOOR
13 C DIAPHRAGM DISCONTINUITY
OUT OF PLANE
DISCONTINUITY
r
/
'i
vA
'///,
?//,
>d
d
d
'///,
ks
SHEAR WALL
BUILDING SECTION
SHEAR WALL
13 D OUT - OF - PLANE OFFSETS
SHEAR WALL
\
13 E NON - PARALLEL SYSTEM
Fig. 13 Plan Irregularities
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
67
0\
00
STOREY STIFFNESS
FOR THE BUILDING
1 1 1 1
Mill
Mill
L_1_J 1 l_
_ mmm _ _ ■■
l l
wJ9MPS//SSS/SAf
It- *
*"ii - i
k 2
SOFT STOREY WHEN
M<0.7 M + 1
or k^nft/^iiil^iilliiii^
■ — * 3
■\A A STIFFNFSS IRRPfil il ARITV
/
HEAVY
MASSn
2
>
Hi
o
H
H*
>!
O
n
/^
3
lim.msiism'smM
*//////£
JAPM
VMM
WM
%
Vr
WMWWWMMMM
X-
mmmm.mmmm.
WEIQ3HT
w n
W n - 1
" n-2
W 2
W ,
ww^/^wy/wwswz
MASS RATIO
it d ivimoo inncuuLnni I T
Fig. 14 Vertical Irregularities
MASS IRREGULARITY
WHEN, w. >2.0Wj _-j
or Wj>2.0W j + 1
Continued
A—H
A/L>0.15
q
" ! t r
A I ■■ L - I A
SHEAR WALL
14 C VERTICAL GEOMETRIC IRREGULARITY, WHEN L 2 > 1.5 L,
UPPER
FLOOR
LOWER
FLOOR
STOREY STRENGTH
(LATERAL)
F n
Fn-1
F n -2
-\ 1r
F 3
F 2
Fi
14 E WEAK STOREY,
WHEN F) < 0.8 Fi +1
14 D IN - PLANE DISCONTINUITY VERTICAL ELEMENTS
RESISTING LATERAL FORCE, WHEN b > a
Fig. 14 Vertical Irregularities
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
69
S.4.Z importance tactor I and Kesponse Keduction
Factor R
The minimum value of importance factor, I, for
different building systems shaii be as given in Table 35.
The response reduction factor, /c, for different building
systems shall be as given in Table 36.
5.4.3 Design Imposed Loads for Earthquake Force
Calculation
5.4.3.1 For various loading classes as specified in
IS 875 (Fart 2), the earthquake force snail be calculated
for the full dead load plus the percentage of imposed
load as given in Table 37.
5.4.3.2 For calculating the design seismic forces of
the structure, the imposed load on roof need not be
considered.
ifanie toaueu conuiuon m me ioaa comoinauons
lOaas are comoinea witn me eartnquaKe loaas |tnat is
in load combinations (a) in 5.3.3.1. 1, and (b)
in 5.3.3.1.2]. No further reduction in the imposed load
will be used as envisaged in 3 for number of storeys
above the one under consideration or for large spans
of beams or floors.
5.4.3.4 The proportions of imposed load indicated
above for calculating the lateral design forces for
earthquakes are applicable to average conditions.
Where the probable loads at the tunc of earthquake
are more accurately assessed, the designer may alter
the proportions indicated or even replace the entire
Tahlp 35 Tmnnrtfmop Faotnrs. I
S!
No.
Structure
Important service and community buildings.
SUCu HS uOSpltaiS; SCiiOOiS; niGiiUfficiiuu
structures; emergency buildings like telephone
exchange, television stations, radio stations,
railwav stations^ fire station buildings; lar^e
comxnunity hails like cinemas, assembly hails
anH siijbw^v «tatinn« nnwpr staHnnc
Importance
Factor
1.5
l aDie Jo Kesponse Keauction t actor* 7 /c, lor
Buiiding Systems
(Clauses 5.3.4.2 and 5.4.2)
Si Lateral Load Resisting System R
ii)
iv)
v)
vi)
vii)
via)
ix)
Special RC Moment- Resisting Frame (SMRF) 3 '
a) Concentric Braces
u^i r? *-;„ n-
Steel Moment Resisting Frame designed as per
SF: 6(6)
Building with Shear Walls **'
Load Bearing Masonry Wall Buildings ^
B.) unrcimOrCcu
b) Reinforced with horizontal RC Bands
C) RcHiiOrCcd witii hOfiZOiitai Ru- uaiiuS BTiu
vertical bars at comers of rooms and jambs
of openings
Ordinarv Reinforced Concrete Shear Walls 6;
Ductiie Shear Waiis 7)
Buildings with Dual Systems a)
Ordinary Shear Wall with OMRF
Ordinary Shear Waii with SMRF
Hnrtilp. Shp.ar Wall witVt OMRF
3.0
5.0
4.0
5.0
2.5
3,0
4.0
3.0
4.0
4 S
\\) uucuie onear wan witn mvikf
" me aoove values 01 response reaucuon raciors are to oe usea ior
VmilHinoc with lateral lr\aH rpcicfino *»1<»mpnh anH nnt iiicf fWr thf*
"*** — "-to" "* — **- ™"»* -~— »»^«u..*** b v * v *.. v ..v», —**— j—"- *
lateral load resisting elements built in isolation.
2) OMRF are those designed and detailed as per IS 456 or IS 800
Vint- nnt m^otinrr sfii^ti1*» /4*»toilinrr rdniiirdmdnt oc T\t*r T*J 1 TQOfl
3) SMRF defined in 4.15.2.
4) Buildings with shear walls also include buildings bavins shear
waiis and frames, but where
a) frames are not designed to carry lateral loads, or
b) frames are designed to carry lateral loads but do not fulfil
thp rprmirpmpnfc nf 'Hnal cvctpmc'
6) Prohibited in Zones IV and V.
7 ^ Ductile shear walls are those desired and detailed as "er IS 1 3920
8) Buildings with dual systems consist of shear walls (or braced
frames) and moment resisting frames such that
a) the two systems are designed to resist the total design
f orce j« «*.Q«Qj.+jQ« j their lateral stiffness considering
the interaction of the dual svstem at all floor levels:
U) LUC lUUIIIClll ICSJMltlg 11 dill C 5 ill C UCMgllCU LVJ
indenendentlv resist at least 25 nercent of the design
seismic Dase snear.
JNUltS
1 The design engineer mav choose values of importance factor /
i aoie j / rerceiuage oi imposea Loaa to oe
Considered in Seismic Weight Calculation
(Dn
^ a i n
designed for higher value of I- depending on economy, strategy
Considerations like multi-storey buildings having several
rf«iHpnfin1 unite
scarroiding etc ot snort duration.
Imposed Uniformity Distributed Percentage of Imposed
Up to and including 3.0
Above 3.0
25
50
imposed load proportions by the actual assessed load.
In such cases, where the imposed load is not assessed
as per 5.4.3.1 and 5.4.3.2 only that part of imposed
load, which possesses mass, shall be considered.
Lateral design force for earthquakes shall not be
calculated on contribution of impact effects from
imposed loads.
5.4.3.5 Other loads apart from those given above (for
example, snow and permanent equipment) shall be
considered as appropriate.
5.4.4 Seismic Weight
5.4.4.1 Seismic weight of floors
The seismic weight of each floor is its full dead load
plus appropriate amount of imposed load, as specified
in 5.4.3.1 and 5.4.3.2. While computing the seismic
weight of each floor, the weight of columns and walls
in any storey shall be equally distributed to the floors
above and below the storey.
5.4.4.2 Seismic weight of building
The seismic weight of the whole building is the sum
of the seismic weights of all the floors.
5.4.4.3 Any weight supported in between storeys shall
be distributed to the floors above and below in inverse
proportion to its distance from the floors.
5.4.5 Design Lateral Force
5.4.5.1 Buildings and portions thereof shall be designed
and constructed, to resist the effects of design lateral
force specified in 5.4.5.3 as a minimum.
5.4.5.2 The design lateral force shall first be computed
for the building as a whole. This design lateral force
shall then be distributed to the various floor levels.
The overall design seismic force thus obtained at each
floor level, shall then be distributed to individual lateral
load resisting elements depending on the floor
diaphragm action.
5.4.5.3 Design seismic base shear — The total design
lateral force or seismic base shear (V B ) along any
principal direction shall be determined by the following
expression:
v B =\w
where
A h = Design horizontal acceleration spectrum
value as per 5.3.4.2, using the fundamental
natural period as per 5.4.6 in the considered
direction of vibration; and
W - Seismic weight of the building as
per 5.4.4.2.
5.4.6 Fundamental Natural Period
5.4.6.1 The approximate fundamental natural period
of vibration (T a ), in seconds, of a moment-resisting
frame building without brick infill panels may be
estimated by the empirical expression:
7=0.075 h
: 0.085 h
for RC Frame Building
for Steel Frame Building
where
h = Height of building, in metres. This excludes
the basement storeys, where basement walls
are connected with the ground floor deck or
fitted between the building columns. But, it
includes the basement storeys, when they are
not so connected.
5.4.6.2 The approximate fundamental natural period
of vibration (T a ), in seconds, of all other buildings,
including moment-resisting frame buildings with brick
infill panels, may be estimated by the empirical
expression:
r„ =
0.09/1
4d
where
h
d
Height of building, in metres, as defined
in 5.4.6.1; and
Base dimension of the building at the plinth
level, in metres; and along the considered
direction of the lateral force.
5.4.7 Distribution of Design Force
5.4.7.1 Vertical distribution of base shear to different
floor levels
The design base shear (V B ) computed in 5.4.5.3 shall
be distributed along the height of the building as per
the following expression:
a=v B
where
Q i = Design lateral force at floor i,
Wi = Seismic weight of floor /,
hi = Height of floor i measured from base, and
n = Number of storeys in the building is the
number of levels at which the masses are
located.
5.4.7.2 Distribution of horizontal design lateral force
to different lateral force resisting elements
5.4.7.2.1 In case of buildings whose floors are capable
of providing rigid horizontal diaphragm action, the total
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
71
shear in any horizontal plane shall be distributed to
the various vertical elements of lateral force resisting
system, assuming the floors to be infinitely rigid in
the horizontal plane.
5.4.7.2.2 In case of building whose floor diaphragms
cannot be treated as infinitely rigid in their own plane,
the lateral shear at each floor shall be distributed to
the vertical elements resisting the lateral forces,
considering the in-plane flexibility of the diaphragms.
NOTES
1 A floor diaphragm shall be considered to be flexible, if it
deforms such that the maximum lateral displacement measured
from the chord of the deformed shape at any point of the
diaphragm is more than 1.5 times the average displacement of
the entire diaphragm.
2 Reinforced concrete monolithic slab-beam floors or those
consisting of Prefabricated/Precast elements with topping
reinforced screed can be taken a rigid diaphragms.
5.4.8 Dynamic Analysis
5.4.8.1 Dynamic analysis shall be performed to obtain
the design seismic force, and its distribution to different
levels along the height of the building and to the various
lateral load resisting elements, for the following
buildings:
a) Regular buildings — Those greater than 40 m
in height in Zones IV and V, and those greater
than 90 m in height in Zones II and III.
Modelling as per 5.4,8.4.5 can be used.
b) Irregular buildings (as defined in 5.4.1J —
All framed buildings higher than 12 m in
Zones IV and V, and those greater than 40 m
in height in Zones II and 111.
The analytical model for dynamic analysis of buildings
with unusual configuration should be such that it
adequately models the types of irregularities present
in the building configuration. Buildings with plan
irregularities, as defined in Table 33 (as per 5.4.1),
cannot be modelled for dynamic analysis by the method
given in 5.4.8.4.5
NOTE — For irregular buildings, lesser than 40 m in height in
Zones II and III, dynamic analysis, even though not mandatory,
is recommended.
5.4.8.2 Dynamic analysis may be performed either by
the Time History Method or by the Response Spectrum
Method. However, in either method, the design base
shear (V B ) shall be compared with a base shear (V B )
calculated using a fundamental period 7 , where 7 is
as per 5.4.6. Where V B is less than V B , all the response
quantities (for example, member forces, displacements,
storey forces, storey shears and base reactions) shall
be multiplied by V B /V B ).
5.4.8.2.1 The value of damping for buildings may be
taken as 2 and 5 percent of the critical, for the purposes
of dynamic analysis of steel and reinforced concrete
buildings, respectively.
5.4.8.3 Time history method
Time history method of analysis, when used, shall be
based on an appropriate ground motion and shall be
performed using accepted principles of dynamics.
5.4.8.4 Response spectrum method
Response spectrum method of analysis shall be
performed using the design spectrum specified
by 5.3.4.2, or by a site-specific design spectrum
mentioned in 5.3.4.6.
5.4.8.4.1 Free vibration analysis
Undamped free vibration analysis of the entire building
shall be performed as per established methods of
mechanics using the appropriate masses and elastic
stiffness of the structural system, to obtain natural
periods (T) and mode shapes {0} of those of its modes
of vibration that need to be considered as per 5.4.8.4.2.
5.4.8.4.2 Modes to be considered
The number of modes to be used in the analysis should
be such that the sum total of modal masses of all modes
considered is at least 90 percent of the total seismic
mass and missing mass correction beyond 33 percent.
If modes with natural frequency beyond 33 Hz are to
be considered, modal combination shall be carried out
only for modes up to 33 Hz. The effect of higher modes
shall be included by considering missing mass
correction following well established procedures.
5.4.8.4.3 Analysis of building subjected to design
forces
The building may be analysed by accepted principles
of mechanics for the design forces considered as static
forces.
5.4.8.4.4 Modal Combination
The peak response quantities (for example, member
forces, displacements, storey forces, storey shears and
base reactions) shall be combined as per Complete
Quadratic Combination (CQC) method.
A =
r r
X X ^ A; A.
1=17=1 l y J
where
r = Number of modes being considered,
X i = Response quantity in i th mode,
p r = Cross-modal coefficient / (including sign),
and
Aj = Response quantity in mode j (including
sign).
72
NATIONAL BUILDING CODE OF INDIA
8g 2 (1 + fl) P 15
iJ a-^ 2 ) 2 +4ff 2 isa+^) 2
g = Modal damping ratio (in fraction) as
specified in 5.4.8.2.1,
(5 = Frequency ratio = co /co i
0). = circular frequency in fth mode, and
CO.- circular frequency in yth mode.
Alternatively, the peak response quantities may be
combined as follows:
a) If the building does not have closely-spaced
modes, then the peak response quantity (k)
due to all modes considered shall be obtained
as
A-JZ&J 2
where
A k = Absolute value of quantity in mode k.
b) If the building has a few closely-spaced
modes (see 5.3.3.2), then the peak response
quantity (A*) due to these modes shall be
obtained as
c
where the summation is for the closely-spaced
modes only. This peak response quantity due to
the closely spaced modes Qi) is then combined
with those of the remaining well- separated modes
by the method described in 5.4.8.4.4 (a).
5.4.8.4.5 Buildings with regular, or nominally
irregular, plan configurations may be modelled as a
system of masses lumped at the floor levels with each
mass having one degree of freedom, that of lateral
displacement in the direction under consideration. In
such a case, the following expressions shall hold in
the computation of the various quantities:
a) Modal Mass -
k is given by
M K =
- The modal mass (M ) of mode
Z^ ^
8^ (tj
where
g = Acceleration due to gravity,
ik = Mode shape coefficient at floor i in mode k,
and
W. = Seismic weight of floor L
b) Modal Participation Factors — The modal
participation factor (P K ) of mode k is given
by
^K-
I*, (0j 2
c)
Design lateral Force at Each Floor in Each
Mode — The peak lateral force (g ik ) at floor
i in mode k is given by
where
A K = Design horizontal acceleration spectrum value
as per 5.3.4.2 using the natural period of
vibration (T k ) of mode k.
c) Storey Shear Forces in Each Mode — The
peak shear force (V. K ) acting in storey i in
mode k is given by
^k=XOk
d)
e)
Storey Shear Forces due to All Modes
Considered — The peak storey shear force
(V. ) in storey / due to all modes considered is
obtained by combining those due to each
mode in accordance with 5.4.8.4.4.
Lateral Forces at Each Storey due to All
Modes Considered — The design lateral
forces, F . and F. y at roof and at floor i:
' roof r
F f = V f and
roof roof
F. = V.-V.
5.4.9 Torsion
5.4.9.1 Provision shall be made in all buildings for
increase in shear forces on the lateral force resisting
elements resulting from the horizontal torsional
moment arising due to eccentricity between the centre
of mass and centre of rigidity. The design forces
calculated as in 5.4.8.4.5 are to be applied at the centre
of mass appropriately displaced so as to cause design
eccentricity (5.4.9.2) between the displaced centre of
mass and centre of rigidity. However, negative
torsional shear shall be neglected.
5.4.9.2 The design eccentricity, e^ to be used at floor
i shall be taken as
4 L5
+ 0.05
-0.05
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
73
whichever of these gives the more severe effect
in the shear of any frame where
e d . = static eccentricity at floor i defined as the
distance between centre of mass and centre
of rigidity and
b. - floor plan dimension of floor/, perpendicular
to the direction of force.
NOTE — The factor 1.5 represents dynamic
amplification factor, while the factor 0.05 represents
the extent of accidental eccentricity.
5.4.9.3 In case of highly irregular buildings analysed
according to 5.4.8.4.5, additive shears will be
superimposed for a statically applied eccentricity of
± 0.05^ with respect to the centre of rigidity.
5.4.10 Buildings with Soft Storey
5.4.10.1 In case buildings with a flexible storey, such
as the ground storey consisting of open spaces for
parking that is stilt buildings, special arrangement
needs to be made to increase the lateral strength and
stiffness of the soft/open storey.
5.4.10.2 Dynamic analysis of building is carried out
including the strength and stiffness effects of infills
and inelastic deformations in the members, particularly,
those in the soft storey, and the members designed
accordingly.
5.4.10.3 Alternatively, the following design criteria
are to be adopted after carrying out the earthquake
analysis, neglecting the effect of infill walls in other
storeys:
a) the columns and beams of the soft storey are
to be designed for 2.5 times the storey shears
and moments calculated under seismic loads
specified in the other relevant clauses; or,
b) besides the columns designed and detailed for
the calculated shears and moments, shear
walls placed symmetrically in both directions
of the building as far away from the centre of
the building as feasible; to be designed
exclusively for 1 .5 times the lateral shear force
calculated as before.
5.4.11 Deformations
5.4.11.1 Storey drift limitation
The storey drift in any storey due to the minimum
specified design lateral force, with partial load factor
of 1.0, shall not exceed 0.004 times the storey height.
For the purposes of displacement requirements only
(that is, in 5.4.11.1, 5.4.11.2 and 5.4.11.3 only), it is
permissible to use seismic force obtained from the
computed fundamental period (T) of the building
without the lower bound limit on design seismic force
specified in 5.4.8.2.
There shall be no drift limit for single storey building
which has been designed to accommodate storey drift.
5.4.11.2 Deformation compatibility of non-seismic
members
For building located in seismic Zones IV and V, it shall
be ensured that the structural components, that are not
a part of the seismic force resisting system in the
direction under consideration, do not lose their vertical
load-carrying capacity under the induced moments
resulting from storey deformations equal to R times
the storey displacements calculated as per 5.4.11.1,
where R is specified in Table 36.
NOTE — For instance, consider a flat-slab building in which
lateral load resistance is provided by shear walls. Since the
lateral load resistance of the slab-column system is small, these
are often designed only for the gravity loads, while all the
seismic force is resisted by the shear walls. Even though the
slabs and columns are not required to share the lateral forces,
these deform with rest of the structure under seismic force.
The concern is that under such deformations, the slab-column
system should not lose its vertical load capacity.
5.4.11.3 Separation between adjacent units
Two adjacent buildings, or two adjacent units of the
same building with separation joint in between shall
be separated by a distance equal to the amount R times
the sum of the calculated storey displacements as
per 5.4.11.1 of each of them, to avoid damaging contact
when the two units deflect towards each other. When
floor levels of two similar adjacent units or buildings
are at the same elevation levels, factor R in this
requirement may be replaced by R/2.
5.4.12 Miscellaneous
5.4.12.1 Foundations
The use of foundations vulnerable to significant
differential settlement due to ground shaking shall be
avoided for structures in seismic Zones III, IV and V.
In seismic Zones IV and V, individual spread footings
or pile caps shall be interconnected with ties,
(see 5.2.3.4.1 of IS 4326) except when individual
spread footings are directly supported on rock. All ties
shall be capable of carrying, in tension and in
compression, an axial force equal to AJA times the
larger of the column or pile cap load, in addition to the
otherwise computed forces. Here, A h is as per 5.3.4.2.
5.4.12.2 Cantilever projections
5.4.12.2.1 Vertical projections
Tower, tanks, parapets, smoke stacks (chimneys) and
other vertical cantilever projections attached to
buildings and projecting above the roof, shall be
designed and checked for stability for five times the
design horizontal seismic coefficient A h specified
in 5.3.4.2. In the analysis of the building, the weight
74
NATIONAL BUILDING CODE OF INDIA
of these projecting elements will be lumped with the
roof weight.
5.4.12.2.2 Horizontal projection
All horizontal projections like cornices and balconies
shall be designed and checked for stability for five
times the design vertical coefficient specified in 5.3.4.5.
5.4.12.2.3 The increased design forces specified
in 5.4.11.2.1 and 5.4.12.2.2 are only for designing the
projecting parts and their connections with the main
structures. For the design of the main structure, such
increase need not be considered.
5.4.12.3 Compound walls
Compound walls shall be designed for the design
horizontal coefficient A h with Importance Factor 7=1.0
specified in 6.4.2
5.4.12.4 Connections between parts
All parts of the building, except between the separation
sections, shall be tied together to act as integrated single
unit. All connections between different parts, such as,
beams to columns and columns to their footings, should
be made capable of transmitting a force, in all possible
directions, of magnitude (Q/W { ) times but not less than
0.05 times the weight of the smaller part or the total
of dead and imposed load reaction. Frictional
resistance shall not be relied upon for fulfilling these
requirements.
6 SNOW LOAD
6.1 This clause deals with snow loads on roofs of
buildings. Roofs should be designed for the actual load
due to snow or for the imposed loads specified in 3
whichever is more severe.
NOTE — Mountainous regions in northern parts of India are
subjected to snow fall.
In India, part of Jammu and Kashmir (Baramulah
District, Srinagar District, Anantnag District and Ladakh
District); Punjab and Himachal Pradesh (Chamba, Kulu
Kinnaur District, Mahasu District, Mandi District,
Sirmur District and Simla District); and Uttaranchal
(Dehra Dun District, Tehri Garhwal District, Almora
District and Nainital District) experience snow fall of
varying depths two or three times in a year.
6.2 Notations
(Dimensionless) — Nominal values of the shape
coefficients, taking tin account snow draft, sliding
snow, etc, with subscripts, if necessary.
/. (metres) — Horizontal dimension with numerical
subscripts, if necessary.
k (metres) — Vertical dimensions with numerical
subscripts, if necessary.
(J. (degrees) -
s o (pascals) -
s. (pascals) -
- Roof slope,
- Snow load on ground.
Snow load on roofs.
6.3 Snow Load in Roof(s)
6.3.1 The minimum design snow load on a roof area
or any other area above ground which is subjected to
snow accumulation is obtained by multiplying the snow
load on ground, s by the shape coefficient \i, as
applicable to the particular roof area considered:
= V S o
where
s = Design snow load in Pa on plan area of roof,
\l = Shape coefficient (see 5.4), and
s = Ground snow load in Pa (1 Pa=l N/m 2 )
NOTE — Ground snow load at any place depends on the
critical combination of the maximum depth of undisturbed
aggregate cumulative snow fall and its average density. In
due course the characteristic snow load on ground for
different regions will be included based on studies. Till such
time the users of this code are advised to contact either Snow
and Avalanches Study Establishment (Defence Research and
Development Organization), Manali (HP) or Indian
Meteorological Department (IMD), Pune in the absence of
any specific information for any location.
6.4 Shape Coefficients
6.4.1 General Principles
In perfectly calm weather, falling snow would cover
roofs and the ground with a uniform blanket of snow,
and the design snow load could be considered as a
uniformly distributed load. Truly uniform loading
conditions, however, are rare and have usually only
been observed in areas that are sheltered on all sides
by high trees, buildings, etc. In such a case, the shape
coefficient would be equal to unity.
In most regions, snow-falls are accompanied or followed
by winds. The winds will re-distribute the snow, and on
some roofs especially multilevel roofs, the accumulated
drift load may reach a multiple of the ground load. Roofs
which are sheltered by other buildings, vegetation, etc,
may collect more snow load than the ground level. The
phenomenon is of the sanfe nature as that illustrated for
multi-level roofs in 6.4.2.4.
So far sufficient data are not available to determine
the shape coefficient on a statistical basis. Therefore,
a nominal value is given. A representative sample of
roofs is shown in 6.4.2. However, in special cases such
as strip loading, cleaning of the roof periodically by
deliberate heating of the roof, etc, have to be treated
separately.
The distribution of snow in the direction parallel to
the caves is assumed to be uniform.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
75
6.4.2 Shape Coefficients for Selected Types of Roofs
6.4.2.1
0°<P<30 a
15°<p<30°
30°<P<60°
P>60°
Simple Flat and
Monopitch Roofs
M 1 = 0.8
».-"(■#)
11,-0
Simple Pitched Roofs
(Positive Roof Slope) 1 '
M 2 = M 1 = 0.8
M 2 =0.8 + 0.4(1^)
\*l =0.8
M 2 = Mi=0
6.4.2.2
Simple or Multiple Pitched Roofs
(Negative Roof Slope)
0°<P<30°
30°<P<60°
P>60°
3S^./>
*%
\
1
O.Pl+p2
" 2
Two-Span or Multispan
Roofs
z
M, =0.8
/30+P\
V 30/
M 1 = 0.8
M 2 = 1.6
V 30/
M 2 = 1.i
M,=0
M, =0.8(30^)
M« =0.8
M 2 = 1.
-1 -«(«£)
M 2 =1.6
M/=0
For asymmetrical simple pitched roofs, each side of the roof shall be treated as one half of corresponding symmetrical roofs.
76
NATIONAL BUILDING CODE OF INDIA
6.4.2.3 Simple curved roofs
THE FOLLOWING CASES 1 AND 2 MUST BE EXAMINED
W
Mi
M, = 0.8
CASE1
jj 2 = 0.3 + l0-jp CASE2
M 2 /2
Restriction:
m 2 < 2.3
m = 0if&>60°
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
77
6.4.2.4 Multi-level roofs l)
H, = 0.8
M 2 = M S +M W
where
/X s - due to sliding
u = due to wind
/ 3 - 2h 2) but is restricted as follows:
5m</ 3 <15m
/^ ^
2h s
with the restriction 0.8 <u < 4.0
where
h is in metres
s o is in kilopascals (kilonewtons per square metre)
Jt=2kN/m 2
P > 15° :fi s is determined from an additional load
amounting to 50 percent of the maximum total
load on the adjacent slope of the upper roof 1 *,
and is distributed linearly as shown in the
figure.
P<15°:m=0
A more extensive formula for /x is described in Annex A.
2) If / 2 < / 3 , the coefficient /i is determined by interpolation between
/i 1 and/x 2 .
l) The load on the upper roof is calculated according to 6.4.2.1
or 6.4.2.2.
78
NATIONAL BUILDING CODE OF INDIA
6.4.2.5 Complex multi-level roofs
l 2 + l3>'l
l 2 =2/^/3 =2^:^ =0.8
Restriction:
5 m < / 2 < 15 m;
5m</ 3 < 15 m;
/^ and /i 3 = (jU s + /i w ), are calculated according to 6.4,2.1, 6.4.2.2 and 6.4.2.4.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
79
6.4.2.6 Roofs with local projections and obstructions
i— h
So
h = is in metres
s o - is in kilopascals (kilonewtons per square metre)
k = 2 kN/m 2
ji = 0.8
Restrictions'.
0:8 < ii < 2.0
5m<l<15m
6.4.3 Shape Coefficients in Areas Exposed to Wind
The shape coefficients given in 6.4.2 and Annex K
may be reduced by 15 percent, provided the designer
has demonstrated that the following conditions are
fulfilled:
a) The building is located in an exposed location,
such as open level terrain with only scattered
buildings, trees or other obstructions so that
the roof is exposed to the winds on all sides
and is not likely to become shielded in the
future by obstructions higher than the roof
within a distance from the building equal to
ten times the height of the obstruction above
the roof level; and
b) The roof does not have any significant
projections, such as, parapet walls which may
prevent snow from being blow off the roof.
NOTE — In some areas, winter climate may not be of
such a nature as to produce a significant reduction of
roof loads from the snow load on the ground these areas
area:
a) Winter calm valleys in the mountains where
sometimes layer after layer of snow accumulates
80
NATIONAL BUILDING CODE OF INDIA
on roofs without any appreciable removal of snow
by wind; and
b) Areas (that is, high temperature) where the
maximum snow load may be the result of single
snowstorm, occasionally without appreciable
wind removal.
In such area, the determination of the shape coefficients
shall be based on local experience with due regard to
the likelihood of wind drifting and sliding.
7 SPECIAL LOADS
7.1 This clause gives guidance on loads and load
effects due to temperature changes, soil and hydrostatic
pressures, internally generating stresses (due to creep,
shrinkage, differential settlement, etc), accidental
loads, etc, to be considered in the design of buildings
as appropriate. This clause also includes guidance on
load combinations. The nature of loads to be considered
for a particular situation is to be based on engineering
judgement (see also 3.6)
7.2 Temperature Effects
7.2.1 Expansion and contraction due to changes in
temperature of the materials of a structure shall be
considered in design. Provision shall be made either
to relieve the stress by the provision of expansion/
contraction joints in accordance with good practice
[6-1(10)] or design the structure to carry additional
stresses due to temperature effects as appropriate to
the problem.
7.2.1.1 The temperature range varies for different
regions and under different diurinal and seasonal
conditions. The absolute maximum and minimum
temperature which may be expected in different
localities in Annex B of Part 6 'Structural Design,
Section 6 Steel' respectively. These figures may be
used for guidance in assessing the maximum variations
of temperature.
7.2.1.2 The temperatures indicated are the air
temperatures in the shade. The range of variation in
temperature of the building materials may be
appreciably greater or less than the variation of air
temperature and is influenced by the condition of
exposure and the rate at which the materials composing
the structure absorb or radiate heat. This difference in
temperature variations of the material and air should
be given due consideration.
7.2.1.3 The structural analysis must take account of
changes of the mean (through the section) temperature
in relation to the initial (st) and the temperature gradient
through the section.
a) It should be borne in mind that the changes
of mean temperature in relation to the initial
are liable to differ as between one structural
element and another in buildings or
structures, as for example, between the
external walls and the internal elements of a
building. The distribution of temperature
through section of single-leaf structural
elements may be assumed linear for the
purpose of analysis.
b) The effect of mean temperature changes t x and
t v and the temperature gradients v 1 and v 2 in
the hot and cold seasons for single-leaf
structural elements shall be evaluated on the
basis of analytical principles.
NOTES
1 For portions of the structure below ground level, the
variation of temperature is generally insignificant.
However, during the period of construction, when the
portions of the structure are exposed to weather elements,
adequate provision should be made to encounter adverse
effects, if any.
2 If it can be shown by engineering principles, or if it is
known from experience, that neglect of some or all the
effects of temperature do not affect the structural safety
and serviceability, they need not be considered in design.
7.3 Hydrostatic and Soil Pressure
7.3.1 In the design of structures of parts or structures
below ground level, such as, retaining walls and other
walls in basement floors, the pressure exerted by the
soil or water or both shall be duly accounted for on the
basis of established theories. Due allowance shall be
made for possible surcharge from stationary or moving
loads. When a portion or whole of the soil is blow the
free water surface, the lateral earth pressure shall be
evaluated for weight of soil diminished by buoyancy
and the full hydrostatic pressure.
7.3.1.1 All foundation slabs and other footings
subjected to water pressure shall be designed to resist
a uniformly distributed uplift equal to the full
hydrostatic pressure. Checking of overturning of
foundation under submerged condition shall be done
considering buoyant weight of foundation.
7.3.2 While determining the lateral soil pressure on
column like structural members, such as, pillars which
rest in sloping soils, the wi^lth of the member shall be
taken as follows (see Fig/15).
Actual Width of Member Ratio of Effective Width
to Actual Width
Less than 0.5 m 3.0
Beyond 0.5 m and up to 1 m 3.0 to 2.0
Beyond 1 m 2.0
The relieving pressure of soil in front of the structural
member concerned may generally not be taken into
account.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
81
CO
CM
Fig. 15 Sketch Showing Effective Width of Pilar for Calculating Soil Pressure
7.3.3 Safe-guarding of structures and structural
members against overturning and horizontal sliding
shall be verified. Imposed loads having favourable
effect shall be disregarded for the purpose. Due
consideration shall be given to the possibility of soil
being permanently or temporarily removed.
7.4 Fatigue
7.4.1 General
Fatigue cracks are usually initiated at points of high
stress concentration. These stress concentrations may
be caused by or associated with holes (such as, bolt or
rivet holes in steel structures), welds including stray
or fusions in steel structures, defects in materials, and
local and general changes in geometry of members.
The cracks usually propogate, if loading is continuous.
Where there is such loading cycles, sudden changes
of shape of a member or part of a member, especially
in regions of tensile stress and/or local secondary
bending, shall be avoided. Suitable steps shall be taken
to avoid critical vibrations due to wind and other
causes.
7.4.2 Where necessary, permissible stresses shall be
reduced to allow for the effects of fatigue. Allowance
for fatigue shall be made for combinations of stresses
due to dead load and imposed load. Stresses due to
wind and earthquakes may be ignored when fatigue is
being considered, unless otherwise specified in relevant
codes of practice.
Each element of the structure shall be designed for the
number of stress cycles of each magnitude to which it
is estimated that the element is liable to be subjected
during the expected life of the structure. The number
of cycles of each magnitude shall be estimated in the
light of available date regarding the probable frequency
of occurrence of each type of loading.
NOTE — Apart from the general observations made herein,
the section is unable to provide any precise guidance in
estimating the probabilistic behaviour and response of
structures of various types arising out of repetitive loading
approaching fatigue conditions in structural members, joints,
materials, etc.
7.5 Structural Safety During Construction
7.5.1 All loads required to be carried by the structures
or any part of it due to storage or positioning of
construction materials and erection equipment
including all loads due to operation of such equipment,
shall be considered as erection loads. Proper provision
shall be made, including temporary bracings, to take
care of all stresses due to erection loads. The
conjunction with the temporary bracings shall be
capable of sustaining these erection loads, without
exceeding the permissible stresses specified in
respective codes of practice. Dead load, wind load and
such parts of imposed load, as would be imposed on
82
NATIONAL BUILDING CODE OF INDIA
the structure during the period of erection, shall be
taken as acting together with erection loads.
7.6 Accidental Loads
The occurrence of which, with a significant value, is
unlikely on a given structure over the period of time
under consideration, and also in most cases, is of short
duration. The occurrence of an accidental load could, in
many cases, be expected to cause severe consequences,
unless special measures are taken.
The accidental loads arising out of human action
include the following;
a) Impacts and collisions,
b) Explosions, and
c) Fire.
Characteristic of the above stated loads are that they
are not a consequence of normal use and that they are
undesired, and that extensive effects are made to avoid
them. As a result, the probability of occurrence of an
accidental load is small whereas the consequences may
be severe.
The causes of accidental loads may be:
a) inadequate safety of equipment (due to poor
design or poor maintenance); and
b) wrong operation (due to insufficient teaching
or training, indisposition, negligence or
unfavouable external circumstances).
In most cases, accidental loads only develop under a
combination of several unfavourable occurrence. In
practical applications, it may be necessary to neglect
the most unlikely loads. The probability of occurrence
of accidental loads, which are neglected, may differ
for different consequences of a possible failure. A data
base for a detailed calculation of the probability will
seldom be available.
7.6.1 Impact and Collisions
7.6.1.1 General
During an impact, the kinetic impact energy has to be
absorbed by the vehicle hitting the structure and by
the structure itself. In an accurate analysis, the
probability of occurrence of an impact with a certain
energy object hitting the structure and the structure
itself at the actual place must be considered. Impact
energies for dropped object should be based on the
actual loading capacity and lifting height.
Common sources of impact are:
a) Vehicles;
b) Dropped objects from cranes, fork lifts, etc;
c) Cranes out of control, crane failures; and
d) Flying fragments.
The codal requirements regarding impact from vehicles
and cranes are given in 7.6.1.2 and 7.6.1.3.
7.6.1.2 Collisions between vehicles and structural
elements
In road traffic, the requirement that a structure shall
be able to resist collision may be assumed to be fulfilled
if it is demonstrated that the structural element is able
to stop a fictitious vehicle, as described below. It is
assumed that the vehicle strikes the structural element
at a height of 1.2 m in any possible direction and at a
speed of 10 m/s (36 km/h).
The fictitious vehicle shall be considered to consist of
two masses m x and m 2 which during compression of
the vehicle, produce an impact force increasing
uniformly from zero, corresponding to the
rigidities C x and C r It is assumed that the mass m x is
broken completely before the breaking of mass m 2
begins.
The following numerical values should be used:
m { = 400 kg, C t = 10 000 kN/m, the vehicle is
compressed.
m 2 = 12 000 kg, C 2 = 300 kN/m, the vehicle is
compressed.
NOTE — The described fictitious collision corresponds in
the case of a non-elastic structural element to a maximum static
force of 630 kN for the mass m l and 600 kN for the mass m 2
irrespective of the elasticity, it will therefore be on the safe
side to assume the static force to be 630 kN.
In addition, breaking of the mass m x will result in an
impact wave, the effect of which will depend, to a great
extent, on the kind of structural element concerned.
Consequently, it will not always be sufficient to design
for the static force.
7.6.1.3 Safety railings
With regard to safety, railings put up to protect
structures against collision due to road traffic, it should
be shown that the railings are able to resist the impact
as described in 7.6.1.2.
NOTE — When a vehicle collides with safety railings, the
kinetic energy of the vehicle will be absorbed partly by the
deformation of the railings and partly by the deformation of
the vehicle. The part of the kinetic energy which the railings
should be able to absorb without breaking down may be
determined on the basis of the assumed rigidity of the vehicle
during compression.
7.6.1.4 Crane impact load on buffer stop
The basic horizontal load P y (tones), acting along the
crane track produced by impact of the crane on the
buffer stop, is calculated by the following formula:
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
83
where
V = Speed at which the crane is travelling at the
moment of impact (assumed equal to half
the nominal value) (m/s).
/ = Maximum shortening of the buffer, assumed
equal to 0.1 m for light duty, medium-duty
and heavy-duty cranes with flexible load
suspension and loading capacity not
exceeding 50 t, and 0.2 m in every other
cranes.
M- Reduced crane mass, (t.s 2 /m); and is
obtained by the formula:
M=-
5L+ { P t + kQ) kJ_
4 J
where
8
Q
k
I
= Acceleration due to gravity (9.81 m/s 2 );
= Crane bridge weight (t);
= Crab bridge weight (t);
= Crane loading capacity (t);
= Coefficient, assumed equal to zero for
cranes with flexible load suspension and to
one for cranes with rigid suspension;
= Crane span (m); and
= Nearness of crab (m).
7.6.2 Explosions
7.6.2.1 General
Explosions may cause impulsive loading on a structure.
The following types of explosions are particularly
relevant:
a) Internal gas explosions which may be caused
by leakage of gas piping (including piping
outside the room), evaporation from volatile
liquids or unintentional evaporation from
surface material (for example, fire);
b) Internal dust explosions;
c) Boiler failure;
d) External gas cloud explosions; and
e) External explosions of high explosives (TNT,
dynamite).
The codal requirement regarding internal gas
explosions is given in 7.6.2.2.
7.6.2.2 Explosion effect in closed rooms
Gas explosion may be caused, for example by leaks in
gas pipes (inclusive of pipes outside for room),
evaporation from volatile liquids or unintentional
evaporation of gas from wall sheathings (for example,
caused by fire).
NOTES
1 The effect of explosions depends on the exploding medium,
the concentration of the explosion, the shape of the room,
possibilities of ventilation of the explosion, and the ductility
and dynamic properties of the structure. In rooms with little
possibility for relief of the pressure from the explosion, very
large pressures may occur.
Internal over pressure from an internal gas explosion in rooms
of sizes comparable to residential rooms and with ventilation
areas consisting of window glass breaking at a pressure of
4 kN/m 2 (3-4 mm machine made glass) may be calculated from
the following method:
a) The over pressure is assumed to depend on a factor
AIV, where A is the total windows area in m 2 and V is
the volume in m 3 of the room considered;
b) The internal pressure is assumed to act simultaneously
upon all walls and floors in one closed room; and
c) The action q o may be taken as static action.
If account is taken of the time curve of the action, the
schematic correspondence between pressure and time is
assumed (Fig. 16), where t 1 is the time from the start of
combustion until maximum pressure is reached and t 2 is the
time from maximum pressure to the end of combustion. For
t l and t v the most unfavourable values should be chosen in
relation to the dynamic properties of the structures. However,
the values should be chosen within the intervals as given in
Fig. 17.
2 Figure 16 is based on tests with gas explosions in room
corresponding to ordinary residential flats and should,
therefore, not be applied to considerably different conditions.
The figure corresponds to an explosion caused by town gas
and it might, therefore, be somewhat on the safe side in rooms
where there is only the possibility of gases with a lower rate of
combustion.
The pressure may be applied solely in one room or in more
rooms at the same time. In the latter case, all rooms are
incorporated in the volume V. Only windows or other similarly
weak and light weight structural elements may be taken to be
ventilation areas even though certain limited structural parts
break at pressures less than q o .
Figure 16 is given purely as guide and probability of occurrence
of an explosion should be checked in each case using
appropriate values.
7.6.3 Vertical Load on Air Raid Shelters
7.6.3.1 Characteristic values
As regards buildings in which the individual floors are
acted upon by a total characteristic imposed action of
up to 5.0 kN/m 2 , vertical actions on air raid shelters
generally located below ground level, for example,
basement, etc, should be considered to have the
following characteristic values:
Buildings up to 2 storeys 28 kN/m 2
Buildings with 3-4 storeys 34 kN/m 2
Buildings with more than 4 storeys 41 kN/m 2
Buildings of particularly stable construction 28 kN/m 2
irrespective of the number of storeys
In the case of buildings with floors mat are acted upon
by a characteristic imposed action larger than
5.0 kN/m 2 , the above values should be increased by
the difference between the average imposed action on
all storeys above the one concerned and 5.0 kN/m 2 .
84
NATIONAL BUILDING CODE OF INDIA
— A
1
1
1
1 1 1
30
25
20
15 10 5
m
Fig. 16 Sketch Showing Relation Between Pressure and Time
0.1s <^ <1.0s
1.0s <t 2 < 10s
TIME (s)
Fig. 17 Sketch Showing Time Interval and Pressure
NOTES
1 By storeys it is understood, every utilizable storey above the
shelter.
2 By buildings of a particular stable construction, it is
understood, buildings in which the load-bearing structures are
made from reinforced in-situ concrete.
7.6.4 Fire
7.6.4.1 General
Possible extraordinary loads during a fire may be
considered as accidental actions. Examples are loads
from people along escape routes and loads on another
structure from structure failing because of a fire.
7.6.4.2 Thermal effects during fire
The thermal effect during fire may be determined from
one of the following methods:
a) the time-temperature curve and the required
fire resistance (minutes), and
b) an energy balance method.
If the thermal effect during fire is determined from an
energy balance method, the fire load is taken to be:
q=\lU
where
q = Fire action (kJ per m 2 floor), and
r b = Required fire resistance (minutes) [see
6-1(11)].
NOTE — The fire action is defined as the total quantity of
heat produced by complete combustion of all combustible
material in the fire compartment, inclusive of stored goods
and equipment together with building structures and building
materials.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
85
7.7 Vibrations
For general details on loads due to vibrations, reference
may be made to Annex L.
7.8 Other Loads
Other loads not included in the Section, such as special
loads due to technical process, moisture and shrinkage
effects, etc, should be taken into account where
stipulated by building design codes or established in
accordance with the performance requirement of the
structure.
7.9 For additional information regarding loads, forces
and effects about cyclone resistant buildings and
landslide control aspects, reference may be made to
good practices [6-1(12)] and 6-1(13)] respectively.
8 LOAD COMBINATIONS
8.1 General
A judicious combination of the loads keeping in view
the probability of:
a) their acting together; and
b) their disposition in relation to other loads and
severity of stresses or deformations caused
by the combinations of the various loads, is
necessary to ensure the required safety and
economy in the design of a structure.
8.2 Land Combinations
Keeping the aspect specified in 8.1, the various loads
should, therefore, be combined in accordance with the
stipulation in the relevant design codes. In the absence
of such recommendations, the following loading
combinations, whichever combination produces the
most unfavourable effect in the building, foundation
or structural member concerned may be adopted (as a
general guidance). It should also be recognized in load
combinations that the simultaneous occurrence of
maximum values of wind, earthquake, imposed and
snow loads is not likely.
1)
DL
2)
DL + IL
3)
DL+WL
4)
DL + EL
5)
DL + TL
6)
DL + IL + WL
7)
DL + IL + EL
8)
DL + IL+ TL
9)
DL+WL+TL
10)
DL + EL+ TL
11)
DL + IL+ WL+TL
12)
DL + IL + EL+TL
(DL - dead load, IL = imposed load, WL = wind
load, EL = earthquake load and TL = temperature
load).
NOTES
1 When snow load is present on roofs, replace imposed load
by snow load for the purpose of above load combinations.
2 The relevant design codes shall be followed for permissible
stresses when the structure is designed by working stress
method and for partial safety factors when the structure is
designed by limit stale design method for each of the above
load combinations.
3 Whenever imposed load (IL) is combined with earthquake
load (EL), the appropriate part of imposed load as specified
in 5 should be used, both for evaluating earthquake effect and
also for combined load effects used in such combination.
4 For the purpose of stability of the structure as a whole against
overturning, the restoring moment shall be not less than 1 .2
times the maximum overturning moment due to dead load plus
1.4 times the maximum overturning moment due to imposed
loads. In cases where dead load provides the restoring moment,
only 0.9 times the dead load shall be considered. The restoring
moments due to imposed loads shall be ignored.
5 The structure shall have a factor against sliding of not less
than 1 .4 under the most adverse combination of the applied
loads/forces. In this case, only 0.9 times the dead load shall be
taken into account.
6 Where the bearing pressure on soil due to wind alone is less
than 25 percent of that due to dead load and imposed load, it
may be neglected in design where this exceeds 25 percent,
foundation may be so proportioned that the pressure due to
combined effect of dead load, imposed load and wind load does
not exceed the allowable bearing pressure by more than 25
percent. When earthquake effect is included, the permissible
increase in allowable bearing pressure in the soil shall be in
accordance with 5.
Reduced imposed load specified in 3 for the design of
supporting structures should not be applied in combination
with earthquake forces.
7 Other loads and accidental load combination not included
should be dealt with appropriately.
8 Crane load combinations are covered in 3.6.4.
9 MULTI-HAZARD RISK IN VARIOUS
DISTRICTS OF INDIA
9.1 Multi-Hazard Risk Concept
The commonly encountered hazards are:
a) earthquake,
b) cyclone,
c) wind storm,
d) floods,
e) landslides,
f) liquefaction of soils,
g) extreme winds,
h) cloud bursts, and
j) failure of slopes.
A study of the earthquake, wind/cyclone, and flood
hazard maps of India indicate that there are several
areas in the country which run the risk of being affected
by more than one of these hazards.
86
NATIONAL BUILDING CODE OF INDIA
Further there may be instances where one hazard may
cause occurrence or accentuation of another hazard,
such as landslides may be triggered/accelerated by
earthquakes and wind storms and floods by the
cyclones.
It is important to study and examine the possibility of
occurrence of multiple hazards, as applicable to an area.
However, it is not economically viable to design all
the structures for multiple hazards. The special
structures, such as, nuclear power plants, and life line
structures, such as, hospitals and emergency rescue
shelters may be designed for multiple hazards. For such
special structures, site specific data have to be collected
and the design be carried out based on the accepted
levels of risk. The factors that have to be considered
in determining this risk are:
a) The severity of the hazard characterized by
M.M. (or M.S.K.) intensity in the case of
earthquake; the duration and velocity of wind
in the storms; and unprotected or protected
situation of flood prone areas; and
b) The frequency of occurrence of the severe
hazards.
Till such time that risk evaluation procedures are
formalized, the special structures may be designed for
multiple hazards using the historical data, that can be
obtained for a given site and the available Code for
loads already covered. The designer may have to
consider the loads due to any one of the hazards
individually or in combination as appropriate.
9.2 Multi-Hazard Prone Areas
The criteria adopted for identifying multi hazard prone
areas may be as follows:
a) Earthquake and Flood Risk Prone — Districts
which have seismic Zone of intensity 7 or
more and also flood prone unprotected or
protected area. Earthquake and flood can
occur separately or simultaneously.
b) Cyclone and Flood Risk Prone — Districts
which have cyclone and flood prone areas.
Here floods can occur separately from
cyclones, but simultaneous also along with
prossibility of storm surge too.
c) Earthquake, Cyclone and Flood Risk Prone
— Districts which have earthquake Zone of
intensity 7 or more, cyclone prone as well as
flood prone (protected or unprotected) areas.
Here the three hazards can occur separately
and also simultaneously as in (a) and (b) above
but earthquake and cyclone will be assumed
to occur separately only.
d) Earthquake and Cyclone Risk Prone —
Districts which have earthquake zone of
intensity 7 or more and prone to cyclone
hazard too. The two will be assumed to occur
separately.
Based on the approach given above, the districts with
multi-hazard risk are given in Annex M.
9.3 Use of the List of the District with Multi-hazard
Risk
The list provides some ready information for use of
the authorities involved in the task of disaster
mitigation, preparedness and preventive action. This
information gives the district which are prone to high
risk for more than one hazard. This information will
be useful in establishing the need for developing
housing design to resist the such multi-hazard situation.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
87
ANNEX A
[Clause 3.3.2.1(b)]
ILLUSTRATIVE EXAMPLE SHOWING REDUCTION OF UNIFORMLY DISTRIBUTED
IMPOSED FLOOR LOADS IN MULTI-STOREYED BUILDINGS
FOR DESIGN OF COLUMNS
A-l The total imposed loads from different floor levels
(including the roof) combing on the central column of
a multi-storeyed building (with mixed occupancy) is
shown in Fig. 20. Calculate the reduced imposed
load for the design of column members at different
floor levels using 3.3.2.1. Floor loads do not exceed
5.0 kN/m 2 .
A-l.l Applying reduction coefficients in accordance
with 3.3.2.1, total reduced floor loads on the column
at different levels is indicated along with Fig. 18.
floor No.
FROM TOP
iNCLUDiNG
ROOF
10
11
12
13
14
15
ACTUAL FLOOR
LOAD COMING
ON DiFFERENT
FLOORS kN
30
40
50
50
40
45
50
50
40
40
40
55
55
70
80
ROOF
3
1
3
3
1
1
1
3
1
1
2
3
3
3
3
W//WW.
LOADS FOR WHICH COLUMNS ARE TO BE DESIGNED
kN
30
(30 + 40)(1 -0.1) = 63
(30 + 40 + 50) (1-0.2) = 96
(30 + 40 + 50 + 50)(1-0.3)=119
(30 + 40 + 50 + 50 + 40) (1 - 0.4) = 126
(30 + 40 + 50 + 50 + 40 + 45) (1 - 0.4) = 153
(30 + 40 + 50 + 50 + 40 + 45 + 50) (1 - 0.4) = 183
(30 + 40 + 50 + 50 + 40 + 45 + 50 + 50) (1 - 0,4)
= 213
(30 + 40 + 50 + 50 + 40 + 45 + 50 + 50 + 40)
(1 - 0.4) = 237
(30 + 40 + 50 + 50 + 40 + 45 + 50 + 50 + 40 + 40)
(1-0.4) = 261
(30 + 40 + 50 + 50 + 40 + 45 + 50 + 50 + 40 + 40
+ 40) (i- 0.5) = 237.5 < 261
adopt 261 for design
(30 + 40 + 50 + 50 + 40 + 45 + 50 + 50 + 40 + 40
+ 40 + 55) (1-0.5) = 265
(30 + 40 + 50 + 50 + 40 + 45 + 50 + 50 + 40 + 40
+ 40 + 55 + 55) (1 - 0.5) = 292.5
(30 + 40 + 50 + 50 + 40 + 45 + 50 + 50 + 40 + 40
+ 40 + 55 + 55 + 70) (1 - 0.5) = 327.5
(30 + 40 + 50 + 50 + 40 + 45 + 50 + 50 + 40 + 40
+ 40 + 55 + 55 + 70 + 80) (1 - 0.5) = 367.5
Fig, 18
88
NATIONAL BUILDING CODE OF INDIA
ANNEX B
(Clause 4.2)
NOTATIONS
Surface area of a structure or part of a structure
Effective frontal area
An area at height Z
Breadth of a structure or structural member
normal to be wind stream in the horizontal
plane
Force coefficient/drag coefficient
Normal force coefficient
Transverse force coefficient
Frictional drag coefficient
Pressure coefficient
External pressure coefficient
Internal pressure coefficient
Depth of a structure or structural member
parallel to wind stream
Diameter of cylinder
Force normal to the surface
Normal force
Transverse force
Frictional force
Height of structure above mean ground level
The height of development of a velocity
profile at a distance x down wind from a
change in terrain category
k 2 >= Multiplication factors
3J
A
A
e
A
7,
b
c =
pe
c.=
D
F
F
n
F t
F
h
h
K = Multiplication factor
/ = Length of the member or greater horizontal
dimension of a building
p = Design wind pressure
p = Design wind pressure at height Z
p = External pressure
/?. = Internal pressure
R = Reynolds number
S = Strouhal number
V b = Regional basic wind speed
V h - Mean hourly wind speed corresponding to
10 m height
V = Design wind velocity at height Z
V z = Hourly mean wind speed at height Z
w = Lesser horizontal dimension of a building
or a structural member
vV = Bay within multi-bay buildings
x = Distance down wind from a change in terrain
category
= Wind angle from a given axis
a - Inclination of the roof to the horizontal
= Solidity ratio
Z = A height or distance above the ground
e - Average height of the surface roughness
ANNEX C
(Clause 4.4.2)
BASIC WIND SPEED A 10 m HEIGHT FOR SOME IMPORTANT CITIES/TOWNS
City/Town
Basic Wind Speed
City/Town
Basic Wind Speed
m/s
m/s
Agra
47
Barauni
47
Ahmedabad
39
Bareilly
47
Ajmer
47
Bhatinda
47
Almora
47
Bhilai
39
Amritsar
47
Bhopal
39
Asansol
47
Bhubaneshwar
50
Aurangabad
39
Bhuj
50
Bahraich
47
Bikaner
47
Bangalore
33
Bokaro
47
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
89
City/Town
Basic Wind Speed
City/Town
Basic Wind Speed
m/s
m/s
Calicut
39
Mangalore
39
Chandigarh
47
Moradabad
47
Chennai
50
Mumbai
44
Coimbatore
39
Mysore
33
Cuttack
50
Nagpur
44
Darbhanga
55
Nainital
47
Darjeeling
47
Nasik
39
Dehra Dun
47
Nellore
50
Delhi
47
Panjim
39
Durgapur
47
Patiala
47
Gangtok
47
Patna
47
Guwahati
50
Gaya
39
Pondicheny
50
Gorakhpur
47
Portblair
44
Hyderabad
44
Pune
39
Imphal
47
Raipur
39
Jabalpur
47
Rajkot
39
Jaipur
47
Ranchi
39
Jamshedpur
47
Roorkee
39
Jhansi
47
Rourkela
39
Jodhpur
47
Shimla
39
Kanpur
47
Srinagar
39
Kohima
44
Swat
44
Kolkata
50
Tiruchchirappalli
47
Kurnool
39
Thiruvananthpuram
39
Lakshadweep
39
Udaipur
47
Lucknow
47
Vadodara
44
Ludhiana
47
Varanasi
47
Madurai
39
Vijayawada
50
Mandi
39
Vishakhapatnam
50
ANNEX D
[Clause 4.4.3.2(d)]
CHANGES IN TERRAIN CATEGORIES
D-l LOW TO HIGH NUMBER
D-l.l In cases of transitions from a low category
number (corresponding to a low terrain roughness) to
a high category number (corresponding to a rougher
terrain), the velocity profile over the rougher terrain
shall be determined as follows:
a) Below height h x , the velocities shall be
determined in relation to the rougher terrain;
and
b) Above height h , the velocities shall be
determined in relation to the less rough (more
distant) terrain.
D-2 HIGH TO LOW NUMBER
D-2.1 In cases of transitions from a more rough to a
less rough terrain, the velocity profile shall be
determined as follows:
a) Above height h^ the velocities shall be
determined in accordance with the rougher
(more distant) terrain; and
90
NATIONAL BUILDING CODE OF INDIA
b) Below height h x , the velocities shall be taken
as the lesser of the following:
1) that determined in accordance with the
less rough terrain; and
2) the velocity at height h x as determined in
relation to the rougher terrain.
NOTE — Examples of the determination of velocity
profiles in the vicinity of a change in terrain category
are shown in Fig. 19 (a) and (b).
D-3 MORE THAN ONE CATEGORY
D-3.1 Terrain changes involving more than one
category shall be treated in similar fashion to that
described in A-l and A-2.
NOTE — Examples involving three terrain categories are
shown in Fig. 19(c).
WIND DIRECTION
CATEGORY 2
x 4 = FETCH, h 4 = HEIGHT FOR CATEGORY 4
CATEGORY 4
PROFILE FOR CATEGORY 4
PROFILE FOR CATEGORY 2
DESIGN PROFILE AT A
a) DETERMINATION OF VELOCITY PROFILE NEAR A CHANGE IN TERRAIN CATEGORY
(Less rough to more rough)
x 4 = FETCH, h 4 = HEIGHT FOR CATEGORY 2
- PROFILE FOR CATEGORY 4
PROFILE FOR CATEGORY 2
- DESIGN PROFILE AT A
WIND DIRECTION
CATEGORY 2
b) DETERMINATION OF VELOCITY PROFILE NEAR A CHANGE IN TERRAIN CATEGOR
(More rough to less rough)
Fig. 19 Velocity Profiles in the Vicinity of a Change in Terrain Category — Continued
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
91
x 4 = FETCH, h 4 = HEIGHT FOR CATEGORY 4
x , = FETCH, h , = HEIGHT FOR CATEGORY 1
WIND DIRECTION
hi
AAAAAAAAAAAAAAAAA,
CATEGORY 3
CATEGORY 1
x 1
^S-
h4
A B
CATEGORY 4
x 4
x
g
i
h 4
z
/ /
/ /
/ /
ill
//I
\l
VELOCITY
VELOCITY
VELOCITY
VELOCITY PROFILE FOR CATEGORY 4
VELOCITY PROFILE FOR CATEGORY 3
VELOCITY PROFILE FOR CATEGORY 1
DESIGN PROFILE
c) DETERMINATION OF DESIGN PROFILE INVOLVING MORE THAN ONE CHANGE
TERRAIN CATEGORY
Fig. 19 Velocity Profiles in the Vicinity of a Change in Terrain Category
ANNEX E
(Clause 4.4.3.3)
EFFECT OF A CLIFF OR ESCARPMENT ON THE EQUIVALENT HEIGHT
ABOVE GROUND (k i FACTOR)
E-l The influence of the topographic feature is
considered to extend 1 .5 L, is the effective horizontal
length of the hill depending on slope as indicated below
{see Fig. 20).
Slope
3°<0 <17°
L
e
L
>17°
Z
0.3
where L is the actual length of the upwind slope in the
wind direction, Zis the effective height of the feature,
and is the upwind slope in the wind direction.
If the zone downwind from the crest of the feature is
92
NATIONAL BUILDING CODE OF INDIA
relatively flat, (0 < 3°) for a distance exceeding L e ,
then the feature should be treated as an escarpment. If
not then the feature should be treated as a hill or ridge.
Examples of typical features are given in Fig. 20.
NOTES
1 No difference is made in evaluating k 3 between a three
dimensional hill and two dimensional ridge.
2 In undulating terrain, it is often not possible to decide whether
the local topography to the site is significant in terms of wind
flow. In such cases, the average value of the terrain upwind of
the site for a distance of 5 km should be taken as the base level
from wind to assess the height L and the upwind slope 9 of the
feature.
E-2 TOPOGRAPHY FACTOR, k 3
The topography factor k 3 is given by the following:
k 3 = 1 + C s
where C has the following values:
Slope
3°<0<17°
>17°
1.2
0.36
s is a factor derived in accordance with E-2. 1
appropriate to the height, H above mean ground level
and the distance x from the summit or crest, relative to
the effective length, L e .
E-2.1 The factor s should be determined from:
a) Figure 21 for cliffs and escarpments, and
b) Figure 22 for hills and ridges.
NOTE — Where the downwind slope of a hill or ridge is
greater than 3°, there will be large regions of reduced
accelerations or even shelter and it is not possible to give
general design rules to cater for these circumstances. Values
of s from Fig. 22 may be used as upper bound values.
WIND
[AVERAGE GROUND
LEVEL
REGION AFFECTED BY
TOPOGRAHICAL FEATURE CREST
-2.5 Le-
•""^
-5 km
20 (a) GENERAL NOTATIONS
WIND
CREST
DOWNWIND SLOPE < 3°
W/////&
CREST
DOWNWIND SLOPE > 3°
20 (b) CLIFF AND ESCARPMENT
20 (C) HILL AND RIDGE
Fig. 20 Definition of Topographical Dimensions
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
93
CREST CREST
1
1
K
o
V*
S^
V
\
2.0
1.5
-n H
10 Li
0.5
-1.5 -1.0 -0.5 0.5 1.0 1.5 2.0 2.5
UPWIND g
DOWNWIND f-
Le
Fig. 21 Factor s for Cliff and Escarpment
CREST CREST
1
1
0.1
1
0.2
0.4
ffi
z>
2.0
1.5
1.0
0.5
-1.5 -1.0 -0.5 0.5 1.0 1.5 2.0 2.5
UPWIND g
DOWNWIND r 1
Le
Fig. 22 Factor s for Ridge and Hill
ANNEX F
[Clause 4.5.3.2 (b)]
WIND FORCE ON CIRCULAR SECTIONS
F-l The wind force on any object is given by:
F=C { A e .p d
where
C f = Force coefficient,
A e = Effective area of the object normal to the wind
direction, and
p d = Design pressure of the wind.
For most shapes, the force coefficient remains
approximately constant over the whole range of wind
speeds likely to be encountered. However, for objects
of circular cross-section, it varies considerably.
For a circular section, the force coefficient depends
upon the way in which the wind flows around it and is
94
NATIONAL BUILDING CODE OF INDIA
dependent upon the velocity and kinematic viscosity
of the wind and diameter of the section. The force
coefficient is usually quoted against a non-dimensional
parameter, called the Reynolds number, which takes
account of the velocity and viscosity of the flowing
medium (in the case the wind) and the member
diameter.
Reynolds number, R e =
DV A
where
D
= Diameter of the member;
V d = Design wind speed; and
y = Kinematic viscosity of the air which is
1.46 x 10 5 m 2 /s at 15°C and standard
atmospheric pressure.
Since in most natural environments likely to be found
in India, the kinematic viscosity of the air is fairly
constant, it is convenient to use DV d as the parameter
instead of Reynolds numbers and this has been done
in this Section.
The dependence of a circular section' s force coefficient
or Reynolds number is due to the change in the wake
developed behind the body.
At a low Reynolds number, the wake is as shown in
Fig. 23 and the force coefficient is typically 1.2. As
the Reynolds number is increased, the wake gradually
changes to that shown in Fig. 24, that is, the wake width
d w decreases and the separation point, S moves from
the front to the back of the body.
As a result, the force coefficient shows a rapid drop at
a critical value of Reynolds number, followed by a
gradual rise and Reynolds number is increased still
further.
The variation of C f with parameter DV d is shown in
Fig. 5 for infinitely long circular cylinders having
various values of relative surface roughness e/D when
subjected to wind having an intensity and scale of
turbulence typical of built-up urban areas. The curve
for a smooth cylinder e/D = 1 x 10~ 5 in a steady air-
stream, as found in a low-turbulence wind tunnel is
shown for comparison.
It can be seen that the main effect of free- stream
turbulence is to decrease the critical value of the
parameter DV d . For subcritical flows, turbulence can
produce a considerable reduction in C f below the steady
air-stream values. For super-critical flows, this effect
becomes significantly smaller.
If the surface of the cylinder is deliberately roughened,
such as by incorporating flutes, riveted construction,
etc then the data given in Fig. 5 for appropriate value
of e/D > shall be used.
NOTE — In case of uncertainty regarding the value of e to be
used for small roughness, e/D shall be taken as 0.001.
Fig. 23 Wake in Subcritical Flow
8
/
-Q
dw
s
Fig. 24 Wake in Super-Critical Flow
ANNEX G
(Clause 5.0)
SYMBOLS
The symbols and notations given below apply to the
provisions of this Code:
A h Design horizontal seismic coefficient
A k Design horizontal acceleration spectrum
value for mode k of vibration
i
c
d
ith Floor plan dimension of the building
perpendicular to the direction of force
Index for the closely-spaced
Base dimension of the building, in metres,
in the direction in which the seismic force
is considered.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
95
DL Response quantity due to dead load
e d . Static eccentricity to be used at floor i
calculated as per 5.4.8.2.
e s . Static eccentricity at floor i defined as the
distance between centre of mass and centre
of rigidity
EL x Response quantity due to earthquake load
for horizontal shaking along x-direction
EL Response quantity due to earthquake load
for horizontal shaking along y-direction
EL z Response quantity due to earthquake load
for vertical shaking along z-direction
F roof Design lateral forces at the roof due to all
modes considered
F. Design lateral forces at the floor i due to all
modes considered
g Acceleration due to gravity
h Height of structure, in metres
h. Height measured from the base of the
building to floor /
/ Importance factor
IL Response quantity due to imposed load
M k Modal mass of mode k
n number of storeys
TV SPT value for soil
P k Modal participation factor of mode k
Q. Lateral force at floor /
g ik Design lateral force at floor i in mode k
r Number of modes to be considered as
per 5.4.8.4.2
R Response reduction factor
SJg Average response acceleration coefficient
for rock or soil sites as given by Fig. 2 and
Table 3 based on appropriate natural periods
and damping of the structure
T Undamped natural period of vibration of the
structure (in second)
T Approximate fundamental period (in
second)
T. Fundamental natural period of vibration (in
second)
T k Undamped natural period of mode k of
vibration (in second)
V B Design seismic base shear
V B Design base shear calculated using the
approximate fundamental period T
V. Peak storey shear force in storey i due to all
modes considered
V ik Shear force in storey / in mode k
y roof Peak storey shear force at the roof due to all
modes considered
W Seismic weight of the structure
W { Seismic weight of floor i
Z Zone factor
ik Mode shape coefficient at floor i in mode k
X Peak response (for example, member forces,
displacements, storey forces, storey shears or
base reactions) due to all modes considered
A k Absolute value of maximum response in
mode A:
A c Absolute value of maximum response in
mode c, where mode c is a closely-spaced
mode
X* Peak response due to the closely-spaced
modes only
.P 4j Coefficient used in the Complete Quadratic
Combination (CQC) method while combining
responses of modes / andj
ft). Circular frequency in rad/second in the rth
mode
ANNEX H
{Clause 5.1.15)
COMPREHENSIVE INTENSITY SCALE (MSK 64)
The scale was discussed generally at the inter-
governmental meeting convened by UNESCO in April
1964. Though not finally approved the scale is more
comprehensive and describes the intensity of
earthquake more precisely. The main definitions used
are followings:
a) Type of Structures (Buildings)
Type A — Building in field-stone, rural
structures, unburnt-brick houses,
clay houses.
Type B — Ordinary brick buildings, buildings
of large block and prefabricated
type, half timbered structures,
buildings in natural hewn stone.
96
NATIONAL BUILDING CODE OF INDIA
Type C — Reinforced buildings, well built
wooden structures.
b) Definition of Quantity:
Single, few About 5 percent
Many About 50 percent
Most About 15 percent
c) Classification of Damage to Buildings
Grade 1 Slight
damage
Grade 2 Moderate
damage
Grade 3 Heavy
damage
Grade 4 Destruction
Grade 5 Total
damage
Fine cracks in
plaster: fall of small
pieces of plaster
Small cracks in
plaster: fall of fairly
large pieces of
plaster; pantiles slip
off; cracks in
chimneys parts of
chimneys fall down
Large and deep
cracks in plaster:
fall of chimneys
Gaps in walls: parts
of buildings may
collapse; separate
parts of the
buildings lose their
cohension; and
inner walls collapse
Total collapse of the
buildings
d)
Intensity Scale
1 . Not noticeable — The intensity of the
vibration is below the limits of
sensibility; the tremor is detected and
recorded by seismograph only.
2. Scarcely noticeable (very slight) —
Vibration is felt only by individual people
at rest in houses, especially on upper
floors of buildings.
3. Weak, partially observed only — The
earthquake is felt indoors by a few
people, outdoors only in favourable
circumstances. The vibration is like that
due to the passing of a light truck.
Attentive observers notice a slight
swinging of hanging objects, somewhat
more heavily on upper floors.
4. Largely observed — The earthquake is
felt indoors by many people, outdoors by
few. Here and there people awake, but
no one is frightened. The vibration is like
that due to the passing of a heavily loaded
truck. Windows, doors, and dishes rattle.
Floors and walls crack. Furniture begins
to shake. Hanging objects swing slightly.
Liquid in open vessels are slightly
disturbed. In standing motor cars the
shock is noticeable.
5. Awakening
i) The earthquake is felt indoors by all
outdoors by many. Many people
awake. A few run outdoors uneasy.
Building tremble throughout.
Hanging objects swing considerably.
Pictures knock against walls or
swing out of place. Occasionally
pendulum clocks stop. Unstable
objects overturn or shift. Open doors
and windows are thrust open and
slam back again. Liquids spill in
small amounts from well-filled open
containers. The sensation of
vibration is like that due to heavy
objects falling inside the buildings.
ii) Slight damages in buildings of Type
A are possible.
iii) Sometimes changes in flow # of springs.
6. Frightening
i) Felt by most indoors and outdoors.
Many people in buildings are
frightened and run outdoors. A
few persons loose their balance.
Domestic animals run out of their
stalls in few instances, dishes and
glassware may break and books fall
down. Heavy furniture may possibly
move and small steeple bells may
ring.
ii) Damage of Grade 1 is sustained in
single buildings of Type B and in
many of Type A. Damage in few
buildings of Type A is of Grade 2.
iii) In few cases, cracks up to widths of
1 cm possible in wet ground; in
mountains occasional landslips;
change in flow of springs and in level
of well water are observed.
7 . Damage of buildings
i) Most people are frightened and run
outdoors. Many find it difficult to
stand. The vibration is noticed by
persons driving motor cars. Large
bells ring.
ii) In many buildings of Type C damage
of Grade 1 is caused; in many
buildings of Type B damage is of
Grade 2. Most buildings of Type A
suffer damage of Grade 3, few of
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
97
Grade 4. In single instances,
landslides of roadway on steep slopes;
crack in roads; seams of pipelines
damaged; cracks in stone walls,
iii) Waves are formed on water, and is
made turbid by mud stirred up.
Water levels in wells change, and the
flow of springs changes. Some times
dry springs have their flow resorted
and existing springs stop flowing. In
isolated instances parts of sand and
gravelly banks slip off.
8 . Destruction of buildings
i) Fright and panic; also persons
driving motor cars are disturbed.
Here and there branches of trees
break off. Even heavy furniture
moves and partly overturns. Hanging
lamps are damaged in part.
ii) Most buildings of Type C suffer
damage of Grade 2, and few of Grade
3. Most buildings of Type B suffer
damage of Grade 3. Most buildings
of Type A suffer damage of Grade 4.
Occasional breaking of pipe seams.
Memorials and monuments move and
twist. Tombstones overturn. Stone
walls collapse.
iii) Small landslips in hollows and on
banked roads on steep slopes; cracks
in ground up to widths of several
centimeters. Water in lakes become
turbid. New reservoirs come into
existence. Dry wells refill and
existing wells become dry. In many
cases, change in flow and level of
water is observed.
9. General damage of buildings
i) General panic; considerable damage
to furniture. Animals run to and fro
in confusion, and cry.
ii) Many buildings of Type C suffer
damage of Grade 3, and few of
Grade 4. Most buildings of Type B
show a damage of Grade 4 and a few
of Grade 5. Many buildings of
Type A suffer damage of Grade 5.
Monuments and columns fall.
Considerable damage to reservoirs;
underground pipes partly broken. In
individual cases, railway lines are
bent and roadway damaged.
iii) On flat land overflow of water, sand
and mud is often observed. Ground
cracks in widths of up to 10 cm on
slopes and river banks more than
10 cm. Further more a large number
of slight cracks in ground; falls of
rock, many land slides and earth
flows; large waves in wate. Dry
wells renew their flow and existing
wells dry up.
10. General destruction of buildings
i) Many buildings of Type C suffer
damage of Grade 4, and few of
Grade 5. Many buildings of Type B
show a damage of Grade 5. Most of
Type A have destruction of Grade 5.
Critical damage of dykes and dams.
Severe damage to bridges. Railways
lines are bent slightly. Underground
pipes are bent on broken. Road
paving and asphalt show waves.
ii) In ground, cracks up to widths of
several centimetres, sometimes up to
1 m. Parallel to water courses occur
broad fissures. Loose ground slides
from steep slopes. From river banks
and steep coasts considerable
landslides are possible. In coastal
areas displacement of sand and mud;
change of water level in wells; water
from canals; lakes; rivers; etc,
thrown on land. New lakes occur.
11. Destruction
i) Severe damage even to well built
buildings, bridges, water damps and
railway lines. Highways become
useless. Underground pipes destroyed.
ii) Ground considerably distorted by
broad cracks and fissures, as well as
movement in horizontal and vertical
directions. Numerous landslips and
falls of rocks. The intensity of
the earthquake requires to be
investigated specifically.
12. Landscape changes
i) Practically all structures above and
below ground are greatly damaged
or destroyed.
ii) The surface of the ground is radically
changed. Considerable ground
cracks with extensive vertical and
horizontal movements are observed.
Falling of rock and slumping of river
banks over wide areas, lakes are
damaged, waterfalls appears and
rivers are deflected. The intensity
of the earthquake requires to be
investigated specially.
98
NATIONAL BUILDING CODE OF INDIA
ANNEX J
(Clause 5.3.4.2)
ZONE FACTORS FOR SOME IMPORTANT TOWNS
Town
Zone
Zone Factor, Z
Town
Zone
Zone Factor, Z
Agra
III
0.16
Goa
III
0.16
Ahmedabad
III
0.16
Gulbarga
II
0.10
Ajmer
II
0.10
Gaya
III
0.16
Allahabad
II
0.10
Gorakhpur
IV
0.24
Almora
IV
0.24
Hyderabad
II
0.10
Ambala
IV
0.24
Imphal
V
0.36
Amritsar
IV
0.24
Jabalpur
III
0.16
Asansol
III
0.16
Jaipur
II
0.10
Aurangabad
II
0.10
Jamshedpur
II
0.10
Bahraich
IV
0.24
Jhansi
II
0.10
Bangalore
II
0.10
Jodhpur
II
0.10
Barauni
IV
0.24
Jorhat
V
0.36
Bareilly
III
0.16
Kakrapara
III
0.16
Belgaum
III
0.16
Kalapakkam
III
0.16
Bhatinda
III
0.16
Kanchipuram
III
0.16
Bhilai
II
0.10
Kanpur
III
0.16
Bhopal
II
0.10
Karwar
III
0.16
Bhubaneshwar
III
0.16
Kohima
V
0.36
Bhuj
V
0.36
Kolkata
III
0.16
Bijapur
III
0.16
Kota
II
0.10
Bikaner
III
0.16
Kurnool
II
0.10
Bokaro
III
0.16
Lucknow
III
0.16
Bulandshahr
IV
0.24
Ludhiana
IV
0.24
Burdwan
III
0.16
Madurai
II
0.10
Calicut
III
0.16
Mandi
V
0.36
Chandigarh
IV
0.24
Mangalore
II
0.16
Chennai
III
0.16
Monghyr
IV
0.24
Chitradurga
II
0.10
Moradabad
IV
0.24
Coimbatore
III
0.16
Mumbai
III
0.16
Cuddalore
III
0.16
Mysore
II
0.10
Cuttack
III
0.16
Nagpur
II
0.10
Darbhanga
V
0.36
Nagarjunasagar
II
0.10
Darjeeling
IV
0.24
Nainital
IV
0.24
Dharwad
III
0.16
Nasik
in
0.16
Dehra Dun
IV
0.24
Nellore
in
0.16
Dharampuri
III
0.16
Osmanabad
in
0.16
Delhi
IV
0.24
Panjim
in
0.16
Durgapur
III
0.16
Patiala
in
0.16
Gangtok
IV
0.24
Patna
IV
0.24
Guwahati
V
0.36
Pilibhit
IV
0.24
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
99
Town
Zone
Zone Factor, Z
Town
Zone
Zone Factor, Z
Pondicherry
II
0.10
Tarapur
III
0.16
Pune
III
0.16
Tezpur
V
0.36
Raipur
II
0.10
Thane
III
0.16
Rajkot
III
0.16
Thanjavur
II
0.10
Ranchi
II
0.10
Thiruvananthapuram
III
0.16
Roorkee
IV
0.24
Tiruchchirappalli
II
0.10
Rourkela
II
0.10
Tiruvennamalai
III
0.16
Sadiya
V
0.36
Udaipur
II
0.10
Salem
III
0.16
Vadodara
III
0.16
Shimla
IV
' 0.24
Sironj
II
0.10
Varanasi
III
0.16
Solapur
III
0.16
Vellore
III
0.16
Srinagar
V
0.36
Vijayawada .
III
0.16
Surat
III
0.16
Vishakhapatnam
II
0.10
ANNEX K
(Clauses 6.4.2.4 and 6.4.3)
SHAPE COEFFICIENTS FOR MULTILEVEL ROOFS
A more comprehensive formula for the shape coefficient for multilevel roofs
"" WIND DIRECTION
^.
h
l
/
- li
*
1. J
,
i
1
*
_ i
i — ,, — -j
t
u w = 1+ -(«,/,+ m 2 l 2 )(l 2 -2h)
h
H, = 0.8
Z 3 = 2h
(h and / being in metres)
Restriction:
< kh
where
S o is in kilopascals (kilonewtons per square metre)
100
NATIONAL BUILDING CODE OF INDIA
k is in newtons per cubic metre
/ 3 <15m
Values of m l (m 2 ) for the higher (lower) roof depend
on its profile and are taken as equal to:
0.5 for plane roofs with
i<±
slopes p < 20° and vaulted roofs with — ^ -
/ lo
0.3 for plane roofs with - ,
slopes P < 20° and vaulted roofs with ~r ^ —
/ lo
The coefficients m l and m 2 may be adjusted to take
into account conditions for transfer of snow on the roof
surface (that is wind, temperature, etc).
NOTE — The other condition of loading shall also be tried.
ANNEX L
(Clause 7.7)
VIBRATIONS IN BUILDINGS
L-l GENERAL
In order to design the buildings safe against vibrations,
it is necessary to identify the source and nature of
vibration. Vibrations may be included in the buildings
due to various actions, such as:
a)
b)
c)
d)
e)
f)
g)
h)
human induced vibrations, for example, the
walking or running or a single person or a
number of persons or dancing or motions in
stadia or concert halls;
machine induced vibrations;
wind induced vibrations;
blast induced vibrations;
traffic load, for example, due to rail, fork-lift,
trucks, cars, or heavy vehicles;
airborne vibrations;
crane operations; and
other dynamic actions, such as, wave loads
or earthquake actions.
The dynamic response of buildings for the above
mentioned causes of vibration of buildings may have
to be evaluated by adopting standard mathematical
models and procedures.
The severity or otherwise of these actions have to be
assessed in terms of the limits set for dynamic response
(frequencies and amplitude of motion) of the buildings
related to (a) human comfort, (b) serviceability
requirements, such as, deflections and drifts and
separation distances to avoid damage due to pounding,
and (c) limits set on the frequencies and amplitude of
motion for machines and other installations.
In order to verify that the set limits are not exceeded,
the actions may be modelled in terms of force-time
histories for which the structural responses may be
determined as time histories of displacements or
accelerations by using appropriate analytical/numerical
methods.
L-2 SERVICEABILITY LIMIT STATE
VERIFICATION OF STRUCTURE SUSCEPTIBLE
TO VIBRATIONS
L-2.1 While giving guidance for serviceability limit
state verification of structure susceptible to vibrations,
here it is proposed to deal with the treatment of the
action side, the determination of the structural response
and the limits to be considered for the structural
response to ensure that vibrations are not harmful or
do not lead to discomfort.
L-2.2 Source of Vibrations
Vibrations may be included by the following sources:
a) by the movement of persons as in pedestrian
bridges, floors where people walk, floors
meant for sport or dancing activities, and
floors with fixed seating and spectator
galleries;
b) by working of machines as in machine
foundations and supports, vibrations
transmitted through the ground, and pile
driving operations;
c) by wind blowing on buildings, towers,
chimneys arid masts, guyed masts, pylons,
bridges, cantilevered roofs, airborne
vibrations;
d) induced by traffic on rail or road bridges
and car park structures and exhibition halls;
and
e) by earthquakes.
L-2.3 Modelling of Actions and Structures
For serviceability limit states, the modelling of these
actions and of the structure depends on how the
serviceability limits are formulated. The serviceability
limit states may refer to:
a) human comfort,
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
101
b) limits for the proper functioning of machines
and other installations, and
c ) maximum deformation limits to avoid damage
or pounding.
In order to verify that these limits are not exceeded,
the actions may be modelled in terms of force-time
histories, for which the structural responses may be
determined as time histories of displacements or
accelerations by using appropriate analytical/
numerical methods. Where the structural response
may significantly influence the force-time histories
to be applied, these interactions have to be
considered either in modelling a combined load-
structure vibration system or by appropriate
modifications of the force-time histories. In addition
to the levels of vibration for which presently limits
have been specified, the possible deformations of
structural members and systems using different
clauses in the relevant codes have to be evaluated
by adopting standard mathematical models and
procedures.
L-2.4 Force-Time Histories
The force-time histories used in the dynamic analysis
should adequately represent the relevant loading
situations for which the serviceability limits are to be
verified. The force-time histories may model:
a) human induced vibrations, for example the
walking or running of a single person or a
number of persons or dancing or motions in
stadia or concert halls;
b) machine induced vibrations, for example by
force vectors due to mass eccentricities and
frequencies, that may be variable with time;
c) wind induced vibrations;
d) blast induced vibrations;
e) traffic load, for example rail, fork-lift, trucks,
cars, or heavy vehicles;
f) airborne vibrations;
g) crane operations; and
h) other dynamic actions such as wave loads or
earthquake actions.
ANNEX M
(Clause 9.2)
SUMMARY OF DISTRICTS HAVING SUBSTANTIAL MULTI-HAZARD RISK AREAS
State
Name of Districts Having Substantial Multi-hazard Prone Area
E.Q. and Rood
Cyclone and Flood
E.Q. Cyclone and Flood
E.Q. and Cyclone
(1)
(2)
(3)
(4)
(5)
Andhra
Adilabad, Karim
Krishna, Nellore,
East Godavari, Guntur,
—
Pradesh
Nagar, Khammam
Srikakulam,
Vi shakhapatnam,
Vizianagram
Prakasam, West Godavari
Assam
All 22 districts listed
in Table 38 could
have M.S.K. IX or
more with flooding
No cyclone, but speed
can be 50 m/s in districts
of Table 38 causing local
damage except Dhubri
Bihar
All 25 districts listed
in Table 38
—
—
—
Goa
—
—
North and South
Goa
Gujarat
Banaskantha, Danthe
—
Ahmedabad, Bharuch,
Amreli,
GS, Gandhinagar,
Surat, Valsad
Bhavnagar,
Kheda, Mahesana,
Jamnagar, Rajkot,
Panchmahals,
Junagad, Kachcha
Vadodara
Haryana
All 8 districts listed
in Table 38
—
—
—
102
NATIONAL BUILDING CODE OF INDIA
(1)
Kerala
(2)
Idduki, Kottayam, Palakkad,
Pathanamthitta
(3)
Maharashtra
Orissa
Ganjam
Punjab
All 12 districts listed in
Table 38
Uttar Pradesh
All 50 districts listed in
Table 38
West Bengal
Birbhum, Darjeeling,
Jalpaiguri, Kooch Bihar,
Malda, Murshidabad,
West Dinajpur
Union
Delhi
Territories
India
139 Districts
(4)
Alappuzha, Emakulum,
Kannur, Kasargode,
Kollam, Kozhikode,
Malappuram,
Thiruvanathapuram,
Trissur
Baleshwar,
Cuttack, Puri
(5)
Bombay, Rayagad,
Ratnagiri,
Sindhudurg, Thane
Dhenkanal
Bardhaman, Calcutta,
Hugli, Howra, Mednipur,
Nadia, North and South
24 Parganas
Yanam (Py)
6 Districts 29 Districts
Bankura
Diu
16 Districts
Table 38 Multi-Hazard Prone Districts
Barpeta, Bongaigaon, Cachar !) , Darrang, Dhemaji, Dhuburi,
Dibrugarh, Goalpara, Golaghat, HailaknadPVJorhat, Kamrup,
Karbianglong, Karimganj 1 *, Kokrajhar, Lakhimpur, Morigaon,
Nagaon, Nalbari, Sibsagar, Sonitpur, Tinsukia
Bihar 2 >
Araria, Begusarai, Bhagalpur, Bhojpur, Darbhanga, Gopalganj,
Katihar, Khagaria, Kishanganj, Madhepura, Madhubani, Munger,
Muzaffarpur, Nalanda, Nawada, Paschim Champaran, Patna,
Purbachamparan, Purnia, Samastipur, Saran, Saharsa, Sitamarhi,
Siwan, Vaishali
3) Haryana
Ambala, Bhiwani, Faridabad, Gurgaon, Hissar, Jind, Kurukshetra,
Rohtak
4) PonJab
Amritsar, Bathinda, Faridkot, Firozpur, Gurdaspur, Hoshiarpur,
Jalandhar, Kapurthala, Ludhiana, Patiala, Rup Nagar, Sangrur
5) Uttar Pradesh
Agra, Aligarh, Allahabad, Azamgarh, Bahraich, Ballia,
Barabanki, Bareilly, Basti, Bijnor, Budaun, Bulandshahr, Deoria,
Etah, Etawah, Faizabad, Farrukhabad, Fatehpur, Firozabad,
Ghaziabad, Ghazipur, Gonda, Gorakhpur, Mardoi, Haridwar,
Jaunpur, Kanpur (Dehat), Kanpur (Nagar), Kheri, Lucknow,
Maharajganj, Mainpuri, Mathura, Mau, Meerut, Mirzapur,
Mordabad, Muzaffarnagar, Nainital, Pilibhit, Partapgarh,
Raebareli, Rampur, Saharanpur, Shahjahanpur, Siddarth Nagar,
Sitapur, Sultanpur, Unnao, Varanasi
n Districts liable to cyclonic storm but No Storm Surge
2) No cyclonic storm in Bihar
3) No cyclonic storm in Haryana
4) No cyclonic storm in Punjab
5) No cyclonic storm in Uttar Pradesh
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and 'accepted standards'
in the fulfilment of the requirements of the Code. The
latest version of a standard shall be adopted at the time
of enforcement of the Code. The standards listed may
be used by the Authority as a guide in conformance
with the requirements of the referred clauses in the
Code.
In the following list, the number appearing in the first
column within parentheses indicates the number of the
reference in this Part/Section.
PART 6 STRUCTURAL DESIGN — SECTION 1 LOADS, FORCES AND EFFECTS
103
IS No.
Title
IS No.
Title
(1) 875
(Part 1) : 1987
(2) 8888
(Part 1) : 1993
(3) 807 : 1976
3177: 1999
(4) 13920 : 1993
(5) 1893
(Part 4) : 2005
(6) 1888 : 1982
6403 : 1981
Code of practice for design
loads (other than earthquake)
for buildings and structures
Part 1 Dead loads — Unit
weights of building material
and stored materials (second
revision)
Guide for requirements of low
income housing: Part 1 Urban
area (first revision)
Code of practice for design,
manufacture, erection and
testing (structural portion)
of cranes and hoists (first
revision)
Code of practice for electric
overhead travelling cranes
and gantry cranes other than
steelwork cranes (second
revision)
Code of practice for ductile
detailing of reinforced concrete
structures subjected to seismic
forces
Criteria for earthquake resistant
design of structures: Part 4
Industrial structures including
stack-like structures
Method of load test on soils
(second revision)
Code of practice for
determination of bearing
capacity of shallow foundations
(first revision)
(7) 1498 : 1970
(8) 2131 : 1981
(9) 4326 : 1993
(10) 3414 : 1968
(11)1642: 1989
(12) 15498 : 2004
(13) 14458
(Part 1) : 1998
(14) 14458
(Part 2) : 1997
(15) 14458
(Part 3) : 1998
(16) 14496
(Part 2) : 1998
(17) 14680 : 1999
Classification and identification
of soils for general engineering
purposes (first revision)
Method for standard penetration
test for soils (first revision)
Code of practice for earthquake
resistant design and construction
of buildings (second revision)
Code of practice for design
and installation of joints in
buildings
Code of practice for fire safety
of buildings (general): Details
of construction (first revision)
Guidelines for improving
cyclone resistance of low rise
houses and other buildings/
structures
Guidelines for retaining wall
for hill area: Part 1 Selection
of type of wall
Guidelines for retaining wall
for hill area: Part 2 Design of
retaining/breast walls
Guidelines for retaining
wall for hill area: Part 3
Construction of dry stone
Guidelines for preparation of
landslide-hazard zonation
maps in mountainous terrains:
Part 2 Macro-zonation
Guidelines for landslide
control
104
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 2 Soils and Foundations
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 SITE INVESTIGATION
4 CLASSIFICATION AND IDENTIFICATION OF SOILS
5 MATERIALS
6 TYPE OF FOUNDATIONS
7 SHALLOW FOUNDATIONS
8 DRIVEN/BORED CAST IN-SITU CONCRETE PILES
9 DRIVEN PRECAST CONCRETE PILES
10 BORED PRECAST CONCRETE PILES
11 UNDER-REAMED PILES
12 TIMBER PILES
13 OTHER FOUNDATIONS
14 GROUND IMPROVEMENT
ANNEX A DETERMINATION OF MODULUS OF ELASTICITY (£) AND
POISSON'S RATIO (//)
ANNEX B DETERMINATION OF MODULUS OF SUBGRADE REACTION
ANNEX C RIGIDITY OF SUPERSTRUCTURE AND FOUNDATION
ANNEX D CALCULATION OF PRESSURE DISTRIBUTION BY
CONVENTIONAL METHOD
ANNEX E CONTACT PRESSURE DISTRIBUTION AND MOMENTS
BELOW FLEXIBLE FOUNDATION
ANNEX F FLEXIBLE FOUNDATION — GENERAL CONDITION
ANNEX G LOAD CARRYING CAPACITY — STATIC FORMULA
ANNEX H DETERMINATION OF DEPTH OF FIXITY, LATERAL
DEFLECTION AND MAXIMUM MOMENT
ANNEX J LOAD CARRYING CAPACITY OF UNDER-REAMED PILES
FROM SOIL PROPERTIES
LIST OF STANDARDS
5
5
7
11
11
11
11
22
27
28
29
31
32
32
33
34
35
36
37
38
39
42
44
45
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
This Section deals with the structural design aspects of foundations and mainly covers the design principles
involved in different types of foundations.
This Section was published in 1970, and subsequently revised in 1983. In the first revision design considerations
in respect of shallow foundation were modified, provisions regarding pier foundation were added and provisions
regarding draft foundation and pile foundation were revised and elaborated.
As a result of experience gained in implementation of 1983 version of the Code and feed back received as well
as revision of standards and preparation of new standards in the field of soils and foundations, a need to revise
this Section was felt. This revision has therefore been prepared to take into account these developments. The
significant changes incorporated in this revision include:
a) Design considerations in respect of shallow foundations have been modified.
b) Method for determining depth of fixity, lateral deflection and maximum moment have been modified.
c) Reference has been made to ground improvement techniques.
d) References to Indian Standards made in the text have been updated.
For detailed information regarding structural analysis and soil mechanics aspects of individual foundations,
reference should be made to standard textbooks and available literature.
The information contained in this Section is mainly based on the following Indian Standards:
IS No. Title
1080 : 1985 Code of practice for design and construction of shallow foundations in soils
(other than raft, ring and shell) (second revision)
1904 : 1986 Code of practice for design and construction of foundations in soils: General
requirements (third revision)
2911 (Part 1/Sec 1) : 1979 Code ofpractice for design and construction ofpile foundations: Part 1 Concrete
piles, Section 1 Driven cast in-situ concrete piles (first revision)
2911 (Part 1/Sec 2) : 1979 Code of practice for design and construction of pile foundations: Part 1 Concrete
piles, Section 2 Bored cast in-situ piles (first revision)
2911 (Part 1/Sec 3) : 1979 Code ofpractice for design and construction ofpile foundations: Part 1 Concrete
piles, Section 3 Driven precast concrete piles (first revision)
2911 (Part 1/Sec 4) : 1984 Code ofpractice for design and construction ofpile foundations: Part 1 Concrete
piles, Section 4 Bored precast concrete piles
291 1 (Part 3) : 1980 Code ofpractice for design and construction ofpile foundations: Part 3 Under-
reamed piles (first revision)
2950 (Part 1) : 1981 Code of practice for design and construction of raft foundations: Part 1 Design
(second revision)
9456 : 1980 Code of practice for design and construction of conical hyperbolic paraboidal
types of shell foundations
All standards, whether given herein above or cross-referred to in the main text of this Section, are subject to
revision. The parties to agreement based on this Section are encouraged to investigate the possibility of applying
the most recent editions of the standards.
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 2 Soils and Foundations
1 SCOPE
This Section covers structural design (principles) of
all building foundations such as raft, pile and other
foundation systems to ensure safety and serviceability
without exceeding the permissible stresses of the
materials of foundations and the bearing capacity of
the supporting soil.
2 TERMINOLOGY
2.0 For the purpose of this Section, the following
definitions shall apply.
2.1 General
2.1.1 Clay — An aggregate of microscopic and
sub-microscopic particles derived from the chemical
decomposition and disintegration of rock constituents.
It is plastic within a moderate to wide range of water
content. The particles are less than 0.002 mm in size.
2.1.2 Clay, Firm — A clay which at its natural water
content can be moulded by substantial pressure with
the fingers and can be excavated with a spade.
2.1.3 Clay, Soft — A clay which at its natural water
content can be easily moulded with the fingers and
readily excavated.
2.1.4 Clay, Stiff — A clay which at its natural water
content cannot be moulded with the fingers and
requires a pick or pneumatic spade for its removal.
2.1.5 Foundation — That part of the structure which
is in direct contact with and transmits loads to the
ground.
2.1.6 Gravel — Cohesionless aggregates of angular
rounded or semi-rounded, fragments of more or less
unaltered rocks or minerals, 50 percent or more of the
particles having size greater than 4.75 mm and less
than 80 mm.
2.1.7 Peat — A fibrous mass of organic matter in
various stages of decomposition generally dark brown
to black in colour and of spongy consistency.
2.1.8 Sand — Cohesionless aggregate of rounded, sub-
rounded, angular, sub-angular or flat fragments of more
or less unaltered rock or minerals, 50 percent or more
of particles greater than 0.075 mm or less
than 4.75 mm in size.
2.1.9 Sand, Coarse — Sand which contains 50 percent
or more of particles of size greater than 2 mm and less
than 4.75 mm.
2.1.10 Sand, Fine — Sand which contains 50 percent
of particles of size greater than 0.075 mm and less
than 0.425 mm.
2.1.11 Sand, Medium — Sand which contains
50 percent of particles of size greater than 0.425 mm
and less than 2.0 mm.
2.1.12 Silt — A fine grained soil with little or no
plasticity. The size of particles ranges from 0.075 mm
to 0.002 mm.
2.1.13 Soft Rock — A rocky cemented material which
offers a high resistance to picking up with pick axes
and sharp tools but which does not normally require
blasting or chiselling for excavation.
2.1.14 Soil, Black Cotton — Inorganic clays of
medium to high compressibility. They form a major
soil group in India. They are predominately
montmorillonitic in structure and yellowish black or
blackish grey in colour. They are characterized by high
shrinkage and swelling properties.
2.1.15 Soil, Coarse Grained — Soils which include
the coarse and largely siliceous and unaltered products
of rock weathering. They possess no plasticity and tend
to lack cohesion when in dry state.
2.1.16 Soil, Fine Grained — Soils consisting of the
fine and altered products of rock weathering,
possessing cohesion and plasticity in their natural state,
the former even when dry and both even when
submerged. In these soils, more than half of the material
by weight is smaller than 75-micron IS Sieve size.
2.1.17 Total Settlement — The total downward
movement of the foundation unit under load.
2.2 Shallow Foundation
2.2.1 Back Fill — Materials used or re-used to fill an
excavation.
2.2.2 Bearing Capacity, Safe — The maximum
intensity of loading that the soil will safely carry with
a factor of safety without risk of shear failure of soil
irrespective of any settlement that may occur.
2.2.3 Bearing Capacity, Ultimate — The intensity of
loading at the base of a foundation which would cause
shear failure of the supporting soil.
2.2.4 Bearing Pressure, Allowable (Gross or Net) —
The maximum allowable loading intensity on the
ground in any given case (with full cognizance of
surcharge) taking into account the maximum safe
bearing capacity, the amount and kind of settlement
expected and the capability of the structure to take up
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
this settlement. It is, therefore, a combined function of
both the site conditions and characteristics of the
particular structure.
The net allowable bearing pressure is the gross allowable
bearing pressure minus the surcharge intensity.
NOTE — The concept of 'gross' and 'net' used in defining
the allowable bearing pressure could also be extended to safe
bearing capacity, safe bearing pressure and ultimate bearing
capacity.
2.2.5 Factor of Safety (with Respect to Bearing
Capacity) — A factor by which the ultimate bearing
capacity (net) must be reduced to arrive at the value of
safe bearing capacity (net).
2.2.6 Footing — A spread constructed in brick work,
masonry or concrete under the base of a wall or column
for the purpose of distributing the load over a larger
area.
2.2.7 Foundation, Raft — A substructure supporting an
arrangement of columns or walls in a row or rows
transmitting the loads to the soil by means of a continuous
slab, with or without depressions or openings.
2.2.8 Make-up Ground — Refuse, excavated soil or
rock deposited for the purpose of filling a depression or
raising a site above the natural surface level of the
ground.
2.2.9 Offset — The projection of the lower step from
the vertical face of the upper step.
2.2.10 Permanent Load — Loads which remain on
the structure for a period, or a number of periods, long
enough to cause time dependent deformation/
settlement of the soil.
2.2.11 Shallow Foundation — A foundation whose
width is generally equal to or greater than its depth.
NOTE — These cover such types of foundations in which load
transference is primarily through shear resistance of the bearing
strata (the frictional resistance of soil above bearing strata is not
taken into consideration) and are laid normally to depth of 3 m.
2.2.12 Spread Foundation — A foundation which
transmits the load to the ground through one or more
footings.
2.3 Pile Foundation
2.3.1 Batter Pile (Raker Pile) — The pile which is
installed at an angle to the vertical.
2.3.2 Bearing Pile — A pile formed in the ground for
transmitting the load of a structure to the soil by the
resistance developed at its tip and/or along its surface.
It may be formed either vertically or at an inclination
(Batter Pile) and may be required to take uplift pressure.
If the pile supports the load primarily by resistance
developed at the pile point or base, it is referred to as
'End Bearing Pile', if support is provided primarily by
friction along its surface, it is referred to as 'Friction Pile 5 .
2.3.3 Bored Cast in-situ Pile — The pile formed within
the ground by excavating or boring a hole within it,
with or without the use of a temporary casing and
subsequently filling it with plain or reinforced concrete.
When the liner is left permanently it is termed as cased
pile and when the casing is taken out it is termed as
uncased pile.
In installing a bored pile the sides of the borehole (when
it does not stand by itself) are required to be stabilized
with the aid of a temporary casing, or with the aid of
drilling mud of suitable consistency. For marine
situations such piles are formed with permanent casing
(liner).
2.3.4 Bored Compaction Pile — A bored cast in-situ
pile with or without bulb(s) in which the compaction
of the surrounding ground and freshly filled concrete
in pile bore is simultaneously achieved by a suitable
method. If the pile is with bulb(s), it is known as under-
reamed bored compaction pile.
2.3.5 Bored Pile — A pile formed with or without
casing by excavating or boring a hole in the ground
and subsequently filling it with plain or reinforced
concrete.
2.3.6 Bored Precast Pile — A pile constructed in
reinforced concrete in a casting yard and subsequently
lowered in the pre-bored holes and the space around
grouted.
2.3.7 Cut-off Level — It is the level where the installed
pile is cut-off to connect the pile caps or beams or any
other structural components at that level.
2.3.8 Driven Cast in-situ Pile — A pile formed within
the ground by driving a casing of permanent or
temporary type and subsequently filling in the hole so
formed with plain or reinforced concrete. For
displacing the subsoil, the casing is installed with a
plug or a shoe at the bottom end. When the casing is
left permanently, it is termed as cased pile and when
the casing is taken out, it termed as uncased pile.
,•■■■
2.3.9 Driven Precast Pil& • — A pile constructed in
concrete (reinforced or prestressed) in a casting yard
and subsequently driven in the ground when it has
attained sufficient strength.
2.3.10 Efficiency of a Pile Group — It is the ratio of
the actual supporting value of a group of piles to the
supporting value arrived at by multiplying the pile
resistance of an isolated pile by their number in the
group.
2.3.11 Factor of Safety — It is the ratio of the ultimate
load capacity of a pile to the safe load of a pile.
NATIONAL BUILDING CODE OF INDIA
2.3.12 Mu hi- Under-Reamed Pile — An under-reamed
pile having more than one bulb. The piles having two
bulbs may be called double under-reamed piles.
2.3.13 Negative Skin Friction — Negative skin friction
is the force developed through the friction between
the pile and the soil in such a direction as to increase
the loading on the pile, generally due to drag of a
consolidating soft layer around the pile resting on a
stiffer bearing stratum such that the surrounding soil
settles more than the pile.
2.3. 14 Ultimate Load Capacity — The maximum load
which a pile can carry before failure of ground when
the soils fails by shear or failure of pile materials.
2.3.15 Under-Reamed Pile — A bored cast in-situ or
bored compaction concrete pile with enlarged bulb(s)
made by either cutting or scooping out the soil or by
any other suitable process.
3 SITE INVESTIGATION
3.1 General
In areas which have already been developed,
information should be obtained regarding the existing
local knowledge, records of trial pits, bore holes, etc,
in the vicinity, and the behaviour of the existing
structures, particularly those of a similar nature to those
proposed. This information may be made use of for
design of foundation of lightly loaded structures of not
more than two storeys and also for deciding scope of
further investigation for other structures.
3.1.1 If the existing information is not sufficient or is
inconclusive, the site should be explored in detail as
per good practice [6-2(1)] so as to obtain a knowledge
of the type, uniformity, consistency, thickness,
sequence and dip of the strata, hydrology of the area
and also the engineering properties. In the case of
lightly loaded structures of not more than two storeys,
the tests required to obtain the above information are
optional, mainly depending on site conditions.
Geological maps of the area give valuable information
of the site conditions. The general topography will
often give some indications of the soil conditions and
their variations. In certain cases the earlier uses of the
site may have a very important bearing on the proposed
new structures.
3.2 Methods of Site Exploration
3.2.1 The common methods of site exploration are
given below:
a) Open trial pits — The method consists of
excavating trial pits and thereby exposing
the subsoil surface thoroughly, enabling
undisturbed samples to be taken from the sides
and bottom of the trial pits. This is suitable
for all types of formations, but should be used
for small depths (up to 3 m). In the case of
cuts which cannot stand below water table,
proper bracing should be given.
b) Auger boring — The auger is either power of
hand operated with periodic removal of the
cuttings.
c) Shell and auger boring — Both manual and
mechanized rig can be used for vertical
borings. The tool normally consists of augers
for soft to stiff clays, shells for very stiff and
hard clays, and shells or sand pumps for sandy
strata attached to sectional boring rods.
d) Wash boring — In wash boring, the soil is
loosened and removed from the bore hole by
a stream of water or drilling mud is worked
up and down or rotated in the bore hole. The
water or mud flow carries the soil up the
annular space between the wash pipe and the
casing, and it overflows at ground level,
where the soil in suspension is allowed to
settle in a pond or tank and the fluid is re-
circulated as required. Samples of the settled
out soil can be retained for identification
purposes but this procedure is often
unreliable. However, accurate identification
can be obtained if frequent 'dry' sampling is
resorted to using undisturbed sample tubes.
e) Sounding/Probing including standard
penetration test, dynamic and static cone
penetration test
f) Geophysical method
g) Percussion boring and rotary boring
h) Pressure meter test
322 Number and Disposition of Test Locations
The number and disposition of various tests shall
depend upon type of structure/buildings and the soil
strata variations in the area. General guidelines are,
however, given below:
a) For a compact building site covering an area
of about 0.4 hectare, one bore hole or trial pit
in each corner and one in the centre should
be adequate.
b) For smaller and less important buildings, even
one bore hole or trial pit in the centre will
suffice.
c) For very large areas covering industrial and
residential colonies, the geological nature of
the terrain will help in deciding the number of
bore holes or trial pits. For plant and other main
structures, number of bore holes and/or trial
pits should be decided considering importance
of structure and type as well as uniformity of
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
strata. In general, dynamic or static cone
penetration tests may be performed at
every 100 m by dividing the area in a grid
pattern and the number of bore holes or trial
pits may be decided by examining the variation
in the penetration curves. The cone penetration
tests may not be possible at sites having
generally bouldery strata. In such cases,
geophysical methods should be resorted to.
3.2.3 Depth of Exploration
The depth of exploration required depends on the type
of proposed structure, its total weight, the size, shape
and disposition of the loaded areas, soil profile, and
the physical properties of the soil that constitutes each
individual stratum. Normally, it should be one and a
half times the width of the footing below foundation
level. In certain cases, it may be necessary to take at
least one bore hole or cone test or both to twice the
width of the foundation. If a number of loaded areas
are in close proximity the effect of each is additive. In
such cases, the whole of the area may be considered
as loaded and exploration should be carried out up to
one and a half times the lower dimension. In weak soils,
the exploration should be continued to a depth at which
the loads can be carried by the stratum in question
without undesirable settlement and shear failure. In any
case, the depth to which seasonal variations affect the
soil should be regarded as the minimum depth for the
exploration of sites. But where industrial processes
affect the soil characteristics this depth may be more.
The presence of fast growing and water seeking trees
also contributes to the weathering processes.
NOTE — Examples of fast growing and water seeking trees are
Banyan (Ficus bengalensis), Pipal (Ficus religiosa) and Neem
(Azadirachta indica).
3.2.3.1 An estimate of the variation with depth of the
vertical normal stress in the soil arising from foundation
loads may be made on the basis of elastic theory. The
net loading intensity at any level below a foundation
may be obtained approximately by assuming a spread
of load of two vertical to one horizontal from all sides
of the foundations, due allowance being made for the
overlapping effects of load from closely spaced footings.
As a general guidance, the depth of exploration at the
start of the work may be decided as given in Table 1,
which may be modified as exploration proceeds, if
required. However, for plant and other main structures,
the depth of exploration may be decided depending upon
importance of structure, loading conditions and type as
well as uniformity of strata.
3.3 Choice of Method for Site Exploration
The choice of the method depends on the following
factors.
3.3.1 Nature of Ground
a) Soils — In clayey soils, borings are suitable
for deep exploration and pits for shallow
exploration. In case of soft sensitive clayey
soils field vane shear test may be carried out
with advantage.
In sandy soils, special equipments may be
required for taking representative samples
below the water table. Standard penetration
test, dynamic cone penetration test and static
cone penetration test are used to assess
engineering properties.
b) Gravel-boulder deposits — In the deposits
where gravel-boulder proportion is large
(>30 percent), the sub-soil strata should be
explored by open trial pits of about 5 m x
5 m but in no case less than 2 m x 2 m. The
depth of excavation may be up to 6 m. For
determining strata characteristics, in-situ
tests should be preferred. For shear
characteristics and allowable soil pressure
dynamic cone penetration tests, load tests on
cast in-situ footing and in-situ shear tests that
is, boulder-boulder test or concrete-boulder
test are more appropriate. For detailed
information on these tests reference may be
made to good practice [6-2(2)]. Depending
on the structure, if required, the strata may
be explored by drilling bore hole using
suitable method.
c) Rocks — Drillings are suitable in hard rocks
and pits in soft rocks. Core borings are
suitable for the identification of types of rock,
but they cannot supply data on joints and
fissures which can be examined only in pits
and large diameter borings.
3.3.2 Topography
In hilly country, the choice between vertical openings
(for example, borings and trial pits) and horizontal
openings (for example, headings) may depend on the
geological structure, sirice steeply inclined strata are
most effectively explored by headings and horizontal
strata by trial pits or borings. Swamps and areas
overlain by water are best explored by borings which
may require use of a floating craft.
3.3.3 Cost
For deep exploration, borings are usual, as deep shafts
are costly. For shallow exploration in soil, the choice
between pits and borings will depend on the nature of
the ground and the information required for shallow
exploration in rock; the cost of bringing a core drill to
the site will be justified only if several holes are
required; otherwise, trial pits will be more economical.
NATIONAL BUILDING CODE OF INDIA
Table 1 Depth of Exploration
(Clause 3.23.1)
SI No.
0)
Type of Foundation
(2)
Depth of Exploration
D
(3)
i) Isolated spread footing or raft
ii) Adjacent footings with clear spacing less
than twice the width
iii) Adjacent rows of footings
iv) Pile and well foundations
v) a) Road cuts
b) Fill
One and a half times the width (B) (see Fig. 1)
One and a half times the length (L) of the footing (see Fig. 1)
See Fig. 1
To a depth of one and a half times the width of structure from the bearing (toe of
pile or bottom of well)
Equal to the bottom width of the cut
Two metres below ground level or equal to the height of the fill whichever is greater
i
i
Li
>B
— — B— *-
m
H - e-
D=1jB FOR A?4B
DM-5 L FOR A<2B
-B— »■
-A — - I * 8
— A— •-
-B-
L = W
-B-
m — A — »4-« — B — »4^ — A — ■■
— B-
-W-
D = 4-jB FOR A<2B
D = 3B FOR A > IB
0=1-56 FOR A=?4B
Fig. 1 Depth of Exploration
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
3.4 Sampling
3.4.1 Methods of Sampling
a) Disturbed samples — These are taken by
methods which modify or destroy the natural
structure of the material though with suitable
precautions the natural moisture content can
be preserved.
b) Undisturbed samples — These are taken by
methods which preserve the structure and
properties of the material. Such samples are
easily obtained from most rocks, but
undisturbed samples of soil can be obtained
only by special methods. Thin walled tube
samples may be used for undisturbed samples
in soils of medium strength and tests for the
same may be carried out in accordance with
good practice [6-2(1)].
NOTE — In case of loose sandy soils and soft soils,
specially below water table it may not be possible to
take undisturbed sample, in which case other suitable
methods may be adopted for exploration.
c) Representative samples — These samples
have all their constituent parts preserved, but
may or may not be structurally disturbed.
3.4.1.1 The methods usually employed are:
Nature of
Type of
Method of Sampling
Ground
Sample
(1)
(2)
(3)
Soil
Disturbed
Chunk samples
Auger samples (for
example, in clay)
Shell samples (for
example, in sand)
Undisturbed
Chunk samples
Tube samples
Rock
Disturbed
Wash samples from
percussion of rotary
drilling
Undisturbed
Core barrel sampling
3.4.2 Soil Samples
a) Disturbed soil samples — The mass of sample
generally required for testing purposes is
given in Table 2.
b) Undisturbed soil samples — The minimum
diameter of the sample shall be 38 mm with
the minimum length/diameter ratio of 2.
3.4.3 Rock Sample
a) Disturbed samples — The sludge from
percussion borings, or from rotary borings
which have failed to yield a core, may be
taken as a disturbed sample.
b) Undisturbed samples
1) Block samples — Such samples taken
from the rock formation shall be dressed
to a size convenient for packing to
about 90 mm x 75 mm x 50 mm.
2) Core sample; see also good practice
[6-2(3)]
3.4.4 Protection, Handling and Labelling of Samples
Care should be taken in protecting, handling and
subsequent transport of samples and in their full
labelling, so that samples can be received in a fit state
for examination and testing, and can be correctly
recognized as coming from a specified trial pit or
boring.
3.4.5 Examination and Testing of Samples
3.4.5.1 The following tests shall be carried out in
accordance with good practice [6-2(4)].
a) Particle size distribution,
b) Density,
c) Natural moisture content,
d) Consistency limits,
e) Consolidation characteristics,
f) Strength characteristics,
g) Sulphate, chloride and pH content of soil and
ground water, and
Table 2 Mass of Soil Sample Required
[Clause 3.4.2(a)]
si
No.
(1)
Purpose of Sample
(2)
Type
Mass of Sample Required
kg
(3)
(4)
Cohesive soil
1
Sands and gravels
3
Cohesive soils and sands
12.5
Gravely soils
25
Cohesive soils and sands
25to50
Gravely soils
SOtolOO
i) Soil identification, natural moisture content tests,
mechanical analysis, and index properties
Chemical tests
ii) Compaction tests
iii) Comprehensive examination of construction
materials including stabilization
10
NATIONAL BUILDING CODE OF INDIA
h) Differential free swelling and swelling
pressure.
4 CLASSIFICATION AND IDENTIFICATION
OF SOILS
The classification and identification of soils for
engineering purposes shall be in accordance with good
practice [6-2(5)].
5 MATERIALS
5.1 Cement, coarse aggregate, fine aggregate, lime,
SURKHI, steel, timber and other materials go into the
construction of foundations shall conform to the
requirements of Part 5 'Building Materials'.
5.2 Protection Against Deterioration of Materials
Where a foundation is to be in contact with soil, water
or air, that is, in a condition conducive to the
deterioration of the materials of the foundation,
protective measures shall be taken to minimize the
deterioration of the materials.
5.2.1 Concrete
In the case of concrete placed against a soil containing
harmful chemicals (sulphates, chlorides), among other
protective measures, it shall be ensured to provide
nominal cover required as prescribed in Part 6
'Structural Design, Section 5 Concrete for the
Applicable Environment Exposure Condition'.
5.2.1.1 Preferably concrete of higher grade shall be
used in situations subject to aggressive environment.
5.2.2 Timber
Where timber is exposed to soil, it shall be treated in
accordance with good practice [6-2(6)].
6 TYPE OF FOUNDATIONS
6.1 Types of foundations covered in this Section
are:
a) Shallow Foundations
1) Pad or spread and strip foundations,
2) Raft foundations, and
3) Ring and shell foundations.
b) Pile Foundations
1) Driven cast in-situ concrete piles,
2) Bored cast in-situ concrete piles,
3) Driven precast concrete piles,
4) Bored precast concrete piles,
5) Under-reamed concrete piles, and
6) Timber piles.
c) Other Foundations
Pier foundations.
7 SHALLOW FOUNDATIONS
7.0 Design Information
For the satisfactory design of foundations, the
following information is necessary:
a) The type and condition of the soil or rock to
which the foundation transfers the loads;
b) The general layout of the columns and load-
bearing walls showing the estimated loads,
including moments and torques due to various
loads (dead load, imposed load, wind load,
seismic load) coming on the foundation units;
c) The allowable bearing pressure of the soils;
d) The changes in ground water level, drainage
and flooding conditions and also the chemical
conditions of the subsoil water, particularly
with respect to its sulphate content;
e) The behaviour of the buildings, topography
and environment/surroundings adjacent to the
site, the type and depths of foundations and
the bearing pressure assumed; and
f) Seismic zone of the region.
7.1 Design Considerations
7.1.1 Design Loads
The foundation shall be proportioned for the following
combination of loads:
a) Dead load + imposed load; and
b) Dead load + imposed load + wind load or
seismic loads, whichever is critical.
For details, reference shall be made to Part 6 'Structural
Design, Section 1 Loads, Forces and Effects'.
NOTES
1 For load, imposed, wind, seismic and other loads, see Part 6
'Structural Design, Section 1 Loads, Forces and Effects'.
2 For coarse grained soils, settlements shall be estimated
corresponding to 7.1.1 (b) and for fine grained soils settlement
shall be estimated corresponding to permanent loads only.
7.1.2 Allowable Bearing Pressure
The allowable bearing pressure shall be taken as either
of the following, whichever is less:
a) The safe bearing capacity on the basis of shear
strength characteristics of soil, or
b) The allowable bearing pressure that the soil
can take without exceeding the permissible
settlement (see 7.1.3).
7.1.2.1 Bearing capacity by calculation
Where the engineering properties of the soil are
available, that is, cohesion, angle of internal friction,
density, etc the bearing capacity shall be calculated
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
11
from stability considerations of shear; factor of safety
of 2.5 shall be adopted for safe bearing capacity. The
effect of interference of different foundations should
be taken into account. The procedure for determining
the ultimate bearing capacity and allowable bearing
pressure of shallow foundations based on shear and
allowable settlement criteria shall be in accordance
with good practice [6-2(7)].
7.1.2.2 Field method for determining allowable
bearing pressure
Where appropriate, plate load tests can be performed
and allowable pressure determined as per good practice
[6-2(8)]. The allowable bearing pressure for sandy soils
may also be obtained by loading tests. When such tests
cannot be done, the allowable bearing pressure for
sands may be determined using penetration test.
7.1.2.3 Where the bearing materials directly under a
foundation over-lie a stratum having smaller safe
bearing capacity, these smaller values shall not be
exceeded at the level of such stratum.
7.1.2.4 Effect of wind and seismic force
Where the bearing pressure due to wind is less than 25
percent of that due to dead and live loads, it may be
neglected in design. Where this exceeds 25 percent
foundations may be so proportioned that the pressure due
to combined dead, live and wind loads does not exceed
the allowable bearing pressure by more than 25 percent.
When earthquake forces are considered for the
computation of design loads, the permissible increase
in allowable bearing pressure of pertaining soil shall
be as given in Table 3, depending upon the type of
foundation of the structure.
7.1.2.5 Bearing capacity of buried strata
If the base of a foundation is close enough to a strata
of lower bearing capacity, the latter may fail due to
excess pressure transmitted to it from above. Care
should be taken to see that the pressure transmitted to
the lower strata is within the prescribed safe limits.
When the footings are closely spaced, the pressure
transmitted to the underlying soil will overlap. In such
cases, the pressure in the overlapped zones will have
to be considered. With normal foundations, it is
sufficiently accurate to estimate the bearing pressure
on the underlying layers by assuming the load to be
spread at a slope of 2 (vertical) to 1 (horizontal).
7.1.3 Settlement
The permissible values of total and differential
settlement for a given type of structure may be taken
as given in Table 4. Total settlements of foundation
due to net imposed loads shall be estimated in
accordance with good practice [6-2(10)]. The following
causes responsible for producing the settlement shall
be investigated and taken into account.
a) Causes of settlement
1) Elastic compression of the foundation
and the underlying soil;
2) Consolidation including secondary
compression;
3) Ground water lowering — Specially
repeated lowering and raising of water
level in loose granular soils tend to
compact the soil and cause settlement of
the footings. Prolonged lowering of the
water table in fine grained soils may
introduce settlement because of the
extrusion of water from the voids.
Pumping water or draining water by tiles
or pipes from granular soils without an
adequate mat of filter material as
protection may, in a period of time, carry
a sufficient amount of fine particles away
from the soil and cause settlement;
4) Seasonal swelling and shrinkage of
expansive clays;
5) Ground movement on earth slope, for
example, surface erosion, slow creep or
landslides; and
6) Other causes, such as adjacent
excavation, mining, subsidence and
underground erosion.
b) Causes of differential settlements
1) Geological and physical non-uniformity
or anomalies in type, structure, thickness,
and density of the soil medium (pockets
of sand in clay, clay lenses in sand, wedge
like soil strata, that is, lenses in soil), an
admixture of organic matter, peat, mud;
2) Non-uniform pressure distribution from
foundation to the soil due to non-uniform
loading and incomplete loading of the
foundations;
3) Water regime at the construction site,
4) Overstressjng of soil at adjacent site by
heavy structures built next to light ones;
5) Overlap of stress distribution in soil from
adjoining structures;
6) Unequal expansion of the soil due to
excavation for footing;
7) Non-uniform development of extrusion
settlements; and
8) Non-uniform structural disruptions or
disturbance of soil due to freezing and
thawing, swelling and softening and
, drying of soils.
12
NATIONAL BUILDING CODE OF INDIA
Table 3 Percentage of Permissible Increase in Allowable Bearing Pressure or
Resistance of Soils
(Clauses 7 A, 2 A and 8,2,7)
SI
No.
Foundation
Type of Soil Mainly Constituting the Foundation
(i)
(2)
Type I — Rock or Hard Soil:
Well graded gravel and sand
gravel mixtures with or without
clay binder, and clayey sands
poorly graded or sand clay
mixtures (GB, CW, SB, SW, and
SC)° having A' 2) above 30, where
TV is the standard penetration
value
(3)
Type II — Medium
Soils: All soils with N
between 10 and 30, and
poorly graded sands or
gravelly sands with little
or no fines (SP 1} ) with
JV>15
(4)
Type HI — Soft Soils:
All soils other than SP S)
with N< 10
(5)
i) Piles passing through any soil but
resting on soil type I
ii) Piles not covered under item (i)
iii) Raft foundations
iv) Combined isolated RCC footing
with tie beams
v) Isolated RCC footing without tie
beams, or unreinforced strip
foundations
vi) Well foundations
50
50
50
50
50
50
25
50
25
25
25
50
25
50
25
25
NOTES
1 The allowable bearing pressure shall be determined in accordance with good practice [6-2(7)] and [6-2(8)].
2 If any increase in bearing pressure has already been permitted for forces other than seismic forces, the total increase in allowable
bearing pressure when seismic force is also included shall not exceed the limits specified above.
3 Desirable minimum fieid values of N — If soils of smaller Af-values are met, compacting may be adopted to achieve these values or
deep pile foundations going to stronger strata should be used.
4 The values of N (corrected values) are at the founding level and the allowable bearing pressure shall be determined in accordance with
good practice [6-2(7)] and [6-2(8)].
Seismic Zone Depth Below Ground N Values
Level (in m)
(1) (2) (3)
Remark
(4)
III, IV and V
(for important
structures only)
<5
>5
<5
>10
15
25
15
25
For values of depths between 5 in
and 10 m, linear interpolation is
recommended
5 The piles should be designed for lateral loads neglecting lateral resistance of soil layers liable to liquefy.
6 Good practice [6-2(5)] and [6-2(9)] may also be referred.
7 Isolated RCC footing without tie beams, or unreinforced strip foundation shall not be permitted in soft soils with N < 10.
See good practice [6=2(5)].
2 > See good practice [6-2(9)].
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
13
Table 4 Permissible Differential Settlements and Tilt (Angular Distortion) for Shallow Foundations in Soils
(Clause 7.1.3)
S]
Type of Structure
Isolated Foundations
Raft Foundations
No.
Sa
^^
^
md and Hard Clay
— ^
Plastic Clay
Sand and Hard Clay
Plastic Clay
__
_^_
_^
_A_
Maximum
settlement
Differential
settlement
->
Angular
distortion
Maximum
settlement
Differential
settlement
Angular
distortion
Maximum Differential
settlement settlement
Angular
distortion
Maximum
settlement
Differential
setdement
Angular
distortion
mm
mm
mm
mm
mm
mm
mm mm
mm
mm
mm
mm
(1)
i)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
1/300
(9) (10)
(ID
(12)
(13)
(14)
For steel structure
50
.003 3L
1/300
50
.003 3L
75 .003 3L
1/300
100
.003 3L
1/300
ii)
For reinforced concrete
structures
50
.001 SL
1/666
75
.001 5L
1/666
75 .002 \L
1/500
100
.002 0L
1/500
iii)
For multistoreyed
buildings
a) RC or steel framed
60
.002L
1/500
75
.002L
1/500
75 .002 SL
1/400
125
.003 3L
1/300
buildings with panel
walls
b) For load bearing
walls
.000 1L
.000 4L
1/5000
1/2500
1) L/H = 2*
2) Z7H = 7*
60
60
.000 2L
.000 4L
1/5 000
1/2 500
60
60
Not likely to
LXZ CIICAJUUICICXJ
iv)
For water towers and
50
.001 SL
1/666
75
,001 SL
1/666
100 .002 SL
1/400
125
.002 SL
1/400
!
silos
NOTE — The values given
requirements of the designer
in the table
may he taken only as a guide and the permissible total settlement/different settlement and tilt (an
igular distortion) in each case
should be decided as per
r
ad
L
denotes the length of deflected part of wall/raft or centre-to-centre distance between columns.
S
H denotes the height of wall from foundation footing.
i
i
s
*
For intermediate ratios of UH, the values can be interpolated.
7.1.4 Depth of Foundations
7.1.4.1 The depth to which foundations should be
carried depends upon the following principal factors:
a) The securing of adequate allowable capacity.
b) In the case of clayey soils, penetration below
the zone where shrinkage and swelling due
to seasonal weather changes, and due to trees
and shrubs are likely to cause appreciable
movements.
c) In fine sands and silts, penetration below the
zone in which trouble may be expected from
frost.
d) The maximum depth of scour, wherever
relevant, should also be considered and the
foundation should be located sufficiently
below this depth.
e) Other factors such as ground movements and
heat transmitted from the building to the
supporting ground may be important.
7.1.4.2 All foundations shall extend to a depth of at
least 500 mm below natural ground level. On rock or
such other weather resisting natural ground, removal
of the top soil may be all that is required. In such cases,
the surface shall be cleaned and, if necessary, stepped
or otherwise prepared so as to provide a suitable
bearing and thus prevent slipping or other unwanted
movements.
7.1.4.3 Where there is excavation, ditch pond, water
course, filled up ground or similar condition adjoining
or adjacent to the subsoil on which the structure is to
be erected and which is likely to impair the stability of
structure, either the foundation of such structure shall
be carried down to a depth beyond the detrimental
influence of such conditions, or retaining walls or
similar works shall be constructed for the purpose of
shielding from their effects.
7.1.4.4 A foundation in any type of soil shall be below
the zone significantly weakened by root holes or
cavities produced by burrowing animals or works. The
depth shall also be enough to prevent the rainwater
scouring below the footings.
7.1.4.5 Clay soils, like black cotton soils, are
seasonally affected by drying, shrinkage and cracking
in dry and hot weather, and by swelling in the following
wet weather to a depth which will vary according to
the nature of the clay and the climatic condition of the
region. It is necessary in these soils, either to place the
foundation bearing at such a depth where the effects
of seasonal changes are not important or to make the
foundation capable of eliminating the undesirable
effects due to relative movement by providing flexible
type of construction or rigid foundations. Adequate
load counteracting against swelling pressures also
provide satisfactory foundations.
7.1.5 Foundation at Different Levels
7.1.5.1 Where footings are adjacent to sloping
ground or where the bottoms of the footings of a
structure are at different levels or at levels different
from those of the footings of adjoining structures,
the depth of the footings shall be such that the
difference in footing elevations shall be subject to
the following limitations:
a) When the ground surface slopes downward
adjacent to a footing, the sloping surface shall
not intersect a frustum of bearing material
under the footing having sides which make
an angle of 30° with the horizontal for soil
and horizontal distance from the lower edge
of the footing to the sloping surface shall be
at least 600 mm for rock and 900 mm for soil
(see Fig. 2).
b) In the case of footings in granular soil, a line
drawn between the lower adjacent edges of
adjacent footings shall not have a steeper
slope than one vertical to two horizontal (see
Fig. 3).
c) In case of footing of clayey soils a line drawn
between the lower adjacent edge of the upper
footing and the upper adjacent edge of lower
footing shall not have a steeper slope than one
vertical to two horizontal (see Fig. 4).
7.1.5.2 The requirement given in 7.1.5.1 shall not
apply under the following conditions:
a) Where adequate provision is made for the
lateral support (such as, with retaining walls)
of the material supporting the higher footing.
b) When the factor of safety of the foundation
soil against shearing is not less than four.
7.1.6 Effect of Seasonal Weather Changes
During periods of hot, dry weather a deficiency of
water develops near the ground surface and in clay
soils, that is associated with a decrease of volume or
ground shrinkage and the development of cracks. The
shrinkage of clay will be increased by drying effect
produced by fast growing and water seeking trees. The
range of influence depends on size and number of trees
and it increase during dry periods. In general, it is
desirable that there shall be a distance of at least 8 m
between such trees. Boiler installations, furnaces, kilns,
underground cables and refrigeration installations and
other artificial sources of heat may also cause increased
volume changes of clay by drying out the ground
beneath them, the drying out can be to a substantial
depth. Special precautions either in the form of
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
15
THESE SURFACES
SHOULD NOT INTERSECT
900 mm min.-
Fig. 2 Footing in Sloping Ground
o o
-SLOPE OF JOINING
LINE NOT STEEPER
THAN TWO HORIZONTAL
TO ONE VERTICAL
Fig. 3 Footing in Granular Soil
LOWER
FOOTING
T&J
■ SLOPE OF JOINING
LINE NOT STEEPER
THAN TWO HORIZONTAL
TO ONE VERTICAL
Fig. 4 Footing in Clayey Soil
LOWER
FOOTING
16
NATIONAL BUILDING CODE OF INDIA
insulation or otherwise should be taken. In periods of
wet weather, clay soils swell and the cracks lend to
close, the water deficiency developed in the previous
dry periods may be partially replenished and a sub-
surface zone or zones deficient in water may persist
for many years. Leakage from water mains and
underground sewers may also result in large volume
changes. Therefore, special care must be taken to
prevent such leakages.
7.1.7 Effect of Mass Movements of Ground in Unstable
Areas
7.1.7.1 In certain areas mass movements of the ground
are liable to occur from causes independent of the loads
applied by the foundations of structures. These include
mining subsidence, landslides on unstable slopes and
creep on clay slopes.
7.1.7.2 Mining subsidence
In mining areas, subsidence of the ground beneath a
building or any other structure is liable to occur. The
magnitude of the movement and its distribution over
the area are likely to be uncertain and attention shall,
therefore, be directed to make the foundations and
structures sufficiently rigid and strong to withstand the
probable worst loading condition.
7.1.7.3 Landslide prone areas
The construction of structures on slopes which are
suspected of being unstable and are subject to landslip
shall be avoided.
On sloping ground on clay soils, there is always a
tendency for the upper layers of soil to move downhill,
depending on type of soil, the angle of slope, climatic
conditions, etc. In some cases, the uneven surface of
the slope on a virgin ground will indicate that the area
is subject to small land slips and, therefore, if used for
foundation, will obviously necessitate special design
consideration.
Where there may be creep of the surface layer of the
soil, protection against creep may be obtained by
following special design considerations.
On sloping sites, spread foundations shall be on a
horizontal bearing and stepped. At all changes of
levels, they shall be lapped at the steps for a distance
at least equal to the thickness of the foundation or
twice the height of the step, whichever is greater. The
steps shall not be of greater height than the thickness
of the foundation, unless special precautions are
taken.
Cuttings, excavations or sloping ground near and below
foundation level may increase the possibility of shear
failure of the soil. The foundation shall be well beyond
the zone of such shear failure.
If the probable failure surface intersects a retaining
wall or other revetment, the latter shall be made strong
enough to resist any unbalanced thrust. In case of doubt
as to the suitability of the natural slopes or cuttings,
the structure shall be kept well away from the top of
the slopes, or the slopes shall be stabilized.
Cuttings and excavations adjoining foundations reduce
stability and increase the likelihood of differential
settlement. Their effect should be investigated not only
when they exist but also when there is possibility that
they are made subsequently.
Where a structure is to be placed on sloping ground,
additional complications are introduced. The ground
itself, particularly if of clay, may be subject to creep
or other forms of instability, which may be enhanced
if the strata dip in the same direction as the ground
surface. If the slope of the ground is large, the overall
stability of the slope and substructure may be affected.
These aspects should be carefully investigated.
7.1.8 Precautions for Foundations on Inclined Strata
In the case of inclined strata, if they dip towards a
cutting of basement, it may be necessary to carry
foundation below the possible slip planes, land
drainage also requires special consideration,
particularly on the uphill side of a structure to divert
the natural flow of water away from the foundations.
7.1.9 Strata of Varying Thickness
Strata of varying thickness, even at appreciable depth,
may increase differential settlement. Where necessary,
calculations should be made of the estimated settlement
from different thickness of strata and the structure
should be designed accordingly. When there is large
change of thickness of soft strata, the stability of
foundation may be affected. Site investigations should,
therefore, ensure detection of significant variations in
strata thickness.
7.1.10 Layers of Softer Material
Some soils and rocks have thin layers of softer material
between layers of harder material, which may not be
detected unless thorough investigation is carried out.
The softer layers may undergo marked changes in
properties if the loading on them is increased or
decreased by the proposed construction or affected by
related changes in ground water conditions. These
should be taken into account.
7.1.11 Spacing Between Existing and New Foundation
The deeper the new foundation and the nearer to the
existing it is located, the greater the damage is likely
to be. The minimum horizontal spacing between
existing and new footings shall be equal to the width
of the wider one. While the adoption of such provision
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
17
shall help minimizing damage to adjacent foundation,
an analysis of bearing capacity and settlement shall be
carried out to have an appreciation of the effect on the
adjacent existing foundation.
7.1.12 Alterations During Construction
a) Where during construction the soil or rock to
which foundation is to transfer loads is found
not to be the type or in the condition assumed,
the foundation shall be re-designed and
constructed for the existing type or conditions
and the Authority notified.
b) Where a foundation bears on gravel, sand or
silt and where the highest level of the ground
water is or likely to be higher than an elevation
defined by bearing surface minus the width
of the footing, the bearing pressure shall be
altered in accordance with Note 4 in Table 3.
c) Where the foundation has not been placed or
located as indicated earlier or is damaged or
bears on a soil whose properties may be
adversely changed by climatic and
construction conditions, the error shall be
corrected, the damaged portion repaired or the
design capacity of the affected foundation
recalculated to the satisfaction of the
Authority.
d) Where a foundation is placed, and if the
results of a load test so indicate, the design of
the foundation shall be modified to ensure
structural stability of the same.
7.2 Pad or Spread and Strip Foundations
7.2.1 In such type of foundations wherever the
resultant of the load deviates from the centre line by
more than 1/6 of its least dimension at the base of
footing, it should be suitably reinforced.
7.2.2 For continuous wall foundations (plain or
reinforced) adequate reinforcement should be provided
particularly at places where there is abrupt change in
magnitude of load or variation in ground support.
7.2.3 On sloping sites the foundation should have a
horizontal bearing and stepped and lapped at changes
of levels for a distance at least equal to the thickness
of foundation or twice the height of step whichever is
greater. The steps should not be of greater height than
thickness of the foundations.
7.2.4 Ground Beams
The foundation can also have the ground beam for
transmitting the load. The ground beam carrying a load
bearing wall should be designed to act with the wall
forming a composite beam, when both are of reinforced
concrete and structurally connected by reinforcement.
The ground beam of reinforced concrete structurally
connected to reinforced brick work can also be used.
7.2.5 Dimensions of Foundation
The dimensions of the foundation in plan should be
such as to support loads as given in good practice
[6-2(11)]. The width of the footings shall be such that
maximum stress in the concrete or masonry is within
the permissible limits. The width of wall foundation
(in mm) shall not be less than that given by:
B = W+300
where
B = Width at base in mm, and
W — Width of supported wall in mm.
7.2.6 In the base of foundations for masonry
foundation it is preferable to have the steps in multiples
of thickness of masonry unit.
7.2.7 The plan dimensions of excavation for
foundations should be wide enough to ensure safe and
efficient working with good practice [6-2(12)].
7.2.8 Unreinforced foundation may be of concrete or
masonry (stone or brick) provided that angular spread
of load from the base of column/wall or bed plate to
the outer edge of the ground bearing is not more than
1 vertical to Vi horizontal to masonry or 1 vertical to 1
horizontal for cement concrete and 1 vertical to 2/3
horizontal for lime concrete. The minimum thickness
of the foundation of the edge should not be less
than 150 mm. In case the depth to transfer the load to
the ground bearing is less than the permissible angle
of spread, the foundations should be reinforced.
7.2.9 If the bottom of a pier is to be belled so as to
increase its load carrying capacity such bell should be
at least 300 mm thick at its edge. The sides should be
sloped at an angle of not less than 45° with the
horizontal. The least dimension should be 600 mm
(circular, square or rectangular). The design should
allow for the vertical tilt of the pier by 1 percent of its
height.
7.2.10 If the allowable bearing capacity is available
only at a greater depth, the foundation can be rested at
a higher level for economic considerations and the
difference in level between the base of foundation and
the depth at which the allowable bearing capacity
occurs can be filled up with either: (a) concrete of
allowable compressive strength not less than the
allowable bearing pressure, (b) in compressible fill
material, for example, sand, gravel, etc, in which case
the width of the fill should be more than the width of
the foundation by an extent of dispersion of load from
the base of the foundation on either side at the rate of
2 vertical to 1 horizontal.
18
NATIONAL BUILDING CODE OF INDIA
7.2.11 The cement concrete foundation (plain or
reinforced) should be designed in accordance with
good practice [6-2(13)] and masonry foundation in
accordance with good practice [6-2(14)].
7.2.12 Thickness of Footing
The thickness of different types of footings, if not
designed according to 7.1, should be as given in
Table 5.
7.2.13 Land Slip Area
On a sloping site, spread foundation shall be on a
horizontal bearing and stepped. At all changes of levels,
they shall be lapped at the steps for a distance at least
equal to the thickness of the foundation or twice the
height of the step, whichever is greater. The steps shall
not be of greater height than the thickness of the
foundation unless special precautions are taken. On
sloping ground on clay soils, there is always a tendency
for the upper layers of soil to move downhill,
depending on type of soil, the angle of slope, climatic
conditions, etc. Special precautions are necessary to
avoid such a failure.
7.2.14 In the foundations, the cover to the reinforcement
shall be as prescribed in Part 6 'Structural Design,
Section 5 Concrete for the Applicable Environment
Exposure Condition'.
7.2.15 For detailed information regarding preparation
of ground work, reference may be made to good
practice [6-2(15)].
7.3 Raft Foundations
7.3.1 Design Considerations
Design provisions given in 7.1 shall generally apply.
7,3.1.1 The structural design of reinforced concrete
rafts shall conform to Part 6 'Structural Design,
Section 5 Concrete'.
7.3.1.2 In the case of raft, whether resting on soil
directly or on lean concrete, the cover to the
reinforcement shall be as prescribed in Part 6
'Structural Design, Section 5 Concrete' for the
applicable environment exposure condition.
7.3.1.3 In case the structure supported by the raft
consists of several parts with varying loads and heights,
it is advisable to provide separation joints between
these parts. Joints shall also be provided wherever there
is a change in the direction of the raft.
7.3.1.4 Foundations subject to heavy vibratory loads
should preferably be isolated.
7.3.1.5 The minimum depth of foundation shall
generally be not less than 1 m.
7.3.1.5 Dimensional parameters
The size and shape of the foundation adopted affect
the magnitude of subgrade modulus and long-term
deformation of the supporting soil and this, in turn,
influences the distribution of contact pressure. This
aspect needs to be taken into consideration in the
analysis.
7.3.1.7 Eccentricity of loading
A raft generally occupies the entire area of the building
and often it is not feasible and rather uneconomical to
proportion it coinciding the centroid of the raft with
the line of action of the resultant force. In such cases,
the effect of the eccentricity on contact pressure
distribution shall be taken into consideration.
7.3.1.8 Properties of supporting soil
Distribution of contact pressure underneath a raft is
affected by the physical characteristics of the soil
supporting it. Consideration must be given to the
increased contact pressure developed along the edges
of foundation on cohesive soils and the opposite effect
Table 5 Thickness of Footings
{Clause 7.2.12)
SI No. Type of Footings
(1) (2)
Thickness of Footings, M in
(3)
Remarks
(4)
ii)
Masonry
Plain concrete
For normal structures
a) 250 mm
b) Twice the maximum projection from the face of
the wall
a) 200 mm
b) Twice the maximum offset in a stepped footing
c) 300 mm
For lightly loaded structures a) 150 mm
b) 200 mm
iii) Reinforced concrete
a) 150 mm
b) 300 mm
Select the greater of the two values
For footings resting on top of the pile
For footings resting on soil
Resting on soil
Resting on pile
Resting on soil
Resting on pile
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
19
on granular soils. Long-term consolidation of deep soil
layers shall be taken into account in the analysis. This
may necessitate evaluation of contact pressure
distribution both immediately after construction and
after completion of the consolidation process. The
design must be based on the worst conditions.
7.3.1.9 Rigidity of foundations
Rigidity of the foundation tends to iron out uneven
deformation and thereby modifies the contact pressure
distribution. High order of rigidity is characterized
by long moments and relatively small, uniform
settlements. A rigid foundation may also generate high
secondary stresses in structural members. The effect
of rigidity shall be taken into account in analysis.
7.3.1.10 Rigidity of the superstructure
Free response of the foundations to soil deformation
is restricted by the rigidity of the superstructure. In the
extreme case, a stiff structure may force a flexible
foundation to behave as rigid. This aspect shall be
considered to evaluate the validity of the contact
pressure distribution.
7.3.1.11 Modulus of elasticity and modulus of
subgrade reaction
Annex A enumerates the methods of determination of
modulus of elasticity (E). The modulus of subgrade
reaction (k) may be determined in accordance with
Annex B.
7.3.2 Necessary Information
The following information is necessary for a
satisfactory design and construction of a raft
foundation:
a) Site plan showing the location of the proposed
as well as the neighbouring structures;
b) Plan and cross-sections of building showing
different floor levels, shafts and openings, etc,
layout of loading bearing walls, columns,
shear walls, etc;
c) Loading conditions, preferably shown on a
schematic plan indicating combination of
design loads transmitted to the foundation;
d) Information relating to geological history of
the area, seismicity of their area, hydrological
information indicating ground water
conditions and its seasonal variations, etc;
e) Geotechnical information giving subsurface
profile with stratification details, engineering
properties of the founding strata (namely,
index properties, effective shear parameters
determined under appropriate drainage
conditions, compressibility characteristics,
swelling properties, results of field tests like
f)
static and dynamic penetration tests, pressure
meter tests etc); and
A review of the performance of similar
structure, if any, in the locality.
7.3.3 Choice of Raft Type
7.3.3.1 For fairly small and uniform column spacing
and when the supporting soil is not too compressible a
flat concrete slab having uniform thickness throughout
(a true mat) is most suitable (see Fig. 5A).
7.3.3.2 A slab may be thickened under heavy loaded
columns to provide adequate strength for shear and
negative moment. Pedestals may also be provided in
such cases (see Fig. 5B).
7.3.3.3 A slab and beam type of raft is likely to be
more economical for large column spacing and unequal
column loads particularly when the supporting soil is
very compressive (see Fig. 5C and 5D).
7.3.3.4 For very heavy structures, provision of cellular
raft or rigid frames consisting of slabs and basement
walls may be considered.
7.3.4 Methods of Analysis
The essential task in the analysis of a raft foundation
is the determination of the distribution of contact
pressure underneath the raft which is a complex
function of the rigidity of the superstructure, the
supporting soil and the raft itself, and cannot be
determined with exactitude, except in very simple
cases. This necessitates a number of simplifying
assumptions to make the problem amenable to analysis.
Once the distribution of contact pressure is determined,
design bending moments and shears can be computed
based on statics. The methods of analysis suggested
are distinguished by the assumptions involved. Choice
of a particular method should be governed by the
validity of the assumptions in the particular case.
7.3.4.1 Rigid foundation (conventional method)
This method is based on the assumption of linear
distribution of contact pressure. The basic assumptions
of this method are:
a) the foundations rigid relative to the supporting
soil and the compressible soil layer is
relatively shallow; and
b) the contact pressure variation is assumed as
planar, such that the centroid of the contact
pressure coincides with the line of action of
the resultant force of all loads acting on the
foundation.
This method may be used when either of the following
conditions is satisfied:
a) The structure behaves as rigid (due to the
20
NATIONAL BUILDING CODE OF INDIA
SECTION AA
5A FLAT PLATE
5 S o b fl
a a a a a
a a a a a
n a an a
7 E
VZZZ&ZZZ&ZZ&ZZZ&
SECTION BB
5B FLAT PLATE THICKENED
UNDER COLUMNS
=r
|q— o~ 3 5
a a a a
a a a a
-B---B-B— B-
d a a a
a a a a
a p D DO
-ycoT"
a a a
a a a
7'
SECTION CC
5C TWO-WAY BEAM
AND SLAB
SECTION DD
5D FLAT PLATE WITH
PEDESTALS
Fig. 5 Common Types of Raft Foundation
b)
combined action of the superstructure and the
foundation) with relative stiffness factor
K> 0.5 (for evaluation of A' see Annex C); and
The column spacing is less than 1.75/A {see
Annex C).
The raft is analysed as a whole in each of the two
perpendicular directions. The contact pressure
distribution is determined by the procedure outlined
in Annex D. Further analysis is also based on statics.
In the case of uniform conditions when the variations in
adjacent column loads and column spacings do not
exceed 20 percent of the higher value, the raft may be
divided into perpendicular strips of widths equal to the
distance between midspans and each strip may be
analysed as an independent beam with known column
loads and known contact pressures. Such beams will
not normally satisfy statics due to shear transfer between
adjacent strips and design may be based on suitable
moment coefficients, or by moment distribution.
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
21
NOTE — On soft soils, for example, normally consolidated
clays, peat, muck, organic silts, ete, the assumptions involved
in the conventional method are commonly justified.
7.3.4.2 Flexible foundations
a) Simplified method — In this method, it is
assumed that the subgrade consists of an
infinite array of individual elastic springs each
of which is not affected by others. The spring
constant is equal to the modulus of subgrade
reaction (k). The contact pressure at any
point under the raft is, therefore, linearly
proportional to the settlement at the point.
Contact pressure may be determined as given
in Annex E. This method may be used when
all the following conditions are satisfied:
1) The structure (combined action of
superstructure and raft) may be
considered as flexible (relative stiffness
factor K > 0.5, see Annex C).
2) Variation in adjacent column load does
not exceed 20 percent of the higher value.
b) General method — For the general case of
a flexible foundation not satisfying the
requirements of (a), the method based on
closed form solution of elastic plate theory
may be used. This method is based on the
theory of plates on winkler foundation which
takes into account the restraint on deflection
of a point provided by continuity of the
foundation in orthogonal foundation. The
distribution of deflection and contact pressure
on the raft due to a column load is determined
by the plate theory. Since the effect of a
column load on an elastic foundation is
damped out rapidly, it is possible to determine
the total effect at a point of all column loads
within the zone of influence by the method
of superimposition. The computation of effect
at any point may be restricted to columns of
two adjoining bays in all directions. The
procedure is outlined in Annex F.
7.4 Ring Foundations
For provisions regarding ring foundations good
practice [6-2(16)] shall be referred to.
8 DRIVEN/BORED CAST IN-SITU CONCRETE
PILES
8.0 General
Piles find application in foundations to transfer load
from a structure to competent sub-surface strata having
adequate load bearing capacity. The load transfer
mechanism from a pile to the surrounding ground is
complicated and is yet to be fully understood, although
application of pile foundations is in practice over many
decades. Broadly, piles transfer axial loads either
substantially by friction along their shafts and/or
substantially by the end bearing. Construction of a pile
foundation requires a careful choice of piling system,
depending upon the subsoil conditions, the load
characteristics of a structure and the limitation of total
settlement, differential settlements and any other
special requirement of a project.
8.1 Material
8.1.1 Concrete
The minimum grade of concrete to be used shall not
be less than that arrived at in accordance with Part 6
'Structural Design, Section 5 Concrete'.
8.1.1.1 For bored and driven cast-in-situ concrete
piles including under-reamed piles
The minimum cement content shall be 400 kg/m 3 in
all conditions. For piles up to 6 m, minimum cement
content of 350 kg/m 3 without provision for under water
concreting may be used under favourable non-
aggressive subsoil condition and where concrete of
higher strength is not needed structurally or due to
aggressive site conditions. For concreting in aggressive
surroundings due to presence of sulphates, etc the
provisions given in Part 6 'Structural Design, Section
5 Concrete' shall be followed.
8.1.2 Steel Reinforcement
Steel reinforcement shall conform to any one of the
types of steel specified in Part 6 'Structural Design,
Section 5 Concrete'.
8.2 Design Considerations
Pile foundation shall be designed in such a way that
the load from the structure it supports can be
transmitted to the soil without causing any soil failure
and without causing such settlement, differential or
total under permanent/transient loading as may result
in structural damage and/or functional distress. The
pile shaft should have adequate structural capacity to
withstand all loads (vertical, axial or otherwise) and
moments which are to be transmitted to the subsoil.
NOTE — When working near existing structures, care shall be
taken to avoid any damage to structures.
8.2.1 Soil Resistance
The bearing capacity of a pile is dependent on the
properties of the soil in which it is embedded. Axial
load from a pile is normally transmitted to the soil
through skin friction along the shaft and end bearing
at its tip. A horizontal load on a vertical pile is
transmitted to the subsoil primarily by horizontal
subgrade reaction generated in the upper part of the
22
NATIONAL BUILDING CODE OF INDIA
shaft. A single pile is normally designed to carry load
along its axis. The transverse load bearing capacity of
a single pile depends on the soil reaction developed
and the structural capacity of the shaft under bending.
In case the horizontal loads are of higher magnitude, it
is essential to investigate the phenomena using
principles of horizontal subsoil reaction adopting
appropriate values for horizontal modulus of the soil.
Alternatively, piles may be installed in rake. The
feasibility of constructing bored piles in rake under a
given subsoil condition should, however, be examined
critically.
8.2.1.1 The ultimate bearing capacity of a pile may
be estimated approximately by means of a static
formula on the basis of soil test results or by test
loading. The settlement of pile obtained at safe load/
working load from load test results on a single pile
shall not be directly used in forecasting the settlement
of a structure unless experience from similar
foundations on its settlement behaviour is available.
The average settlement may be assessed on the basis
of subsoil data and loading details of the structure as a
whole using the principle of soil mechanics.
8.2.1.2 Static formula
By using static formula, the estimated value of the
ultimate bearing capacity of a typical pile is obtained,
the accuracy being dependent on the reliability of the
formula and the reliability of the soil properties for
various strata available. The soil properties to be
adopted in such a formula may be assigned from results
of laboratory tests and field tests as per good practice
[6-2(1)]. Two separate static formulae commonly
applicable for cohesive and non-cohesive soils are
indicated in Annex G, to serve only as a guide. Other
alternative formulae may be applicable, depending on
the subsoil characteristics and method of installation
of piles.
8.2.1.3 Dynamic formula
For driven piles in non-cohesive soils, such as gravels,
coarse sand and other similar deposits, an approximate
value of the bearing capacity may be determined by a
dynamic pile formula as per good practice [6-2(17)].
Dynamic formulae are not directly applicable to
cohesive soil deposits, such as saturated slits and clays,
as the resistance to impact of the toe of the casing will
be exaggerated by their low permeability, while the
frictional resistance on the sides is reduced by
lubrication. If as a result of test loadings on a given
area a suitable coefficient can be applied to a dynamic
formula, the results may then be considered as
reasonable.
8.2.1.4 Load test results
The ultimate load capacity of a single pile is determined
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
with reasonable accuracy from test loading as per good
practice [6-2(18)]. The load test on a pile shall not be
carried out earlier than four weeks from the time of
casting the pile.
8.2.1.5 Non-destructive testing
For quality assurance of concrete piles, non-destructive
integrity test may be carried out prior to laying of beam/
caps, in accordance with good practice [6-2(19)].
8.2.2 Negative Skin Friction or Dragdown Force
When a soil stratum, through which a pile shaft has
penetrated into an underlying hard stratum, compresses
as a result of either its being unconsolidated or its being
under a newly placed fill or as a result of re-moulding
during driving of the pile, a dragdown force is
generated along the pile shaft up to a point in depth
where the surrounding soil does not move downwards
relative to the pile shaft. Recognition of the existence
of such a phenomenon shall be made and a suitable
reduction shall be made to the allowable load, where
appropriate.
8.2.3 Structural Capacity
The piles shall have the necessary structural strength
to transmit the loads imposed on them ultimately to
the soil.
8.2.3.1 Axial capacity
Where a pile is fully embedded in the soil (having an
undrained shear strength not less than 10 kN/m 2 ) its
axial carrying capacity is not limited by its strength as
a long column. Where piles are installed through very
weak soils (having an undrained shear strength less
than 10 kN/m 2 ), special consideration shall be given
to determine whether the shaft would behave as a long
column or not; if necessary suitable reductions shall
be made in its structural strength considering the
buckling phenomenon.
When the finished pile projects above ground level
and is not secured agakist buckling by adequate
bracing, the effective length will be governed by the
fixity conditions imposed on it by the structure it
supports and by the nature, of the soil into which it is
installed. The depth below the ground surface to the
lower point of contraflexure varies with the type of
soil. In good soil the lower point of contraflexure may
be taken at a depth of 1 m below ground surface
subject to a minimum of three times the diameter of
the shaft. In weak soil (undrained shear strength less
than 10 kN/m 2 ) such as soft clay and soft slit, this point
may be taken at about half the depth of penetration
into such stratum but not more than 3 m or 10 times
the diameter of the shaft, whichever is less. A stratum
of liquid mud should be treated as if it was water.
The degree of fixity of the position and inclination
23
of the pile top and the restraint provided by any
bracing shall be estimated following accepted
structural principles.
8.2.3.2 Uplift capacity
Total uplift capacity of pile will be the sum of the
frictional resistance and weight of the pile (buoyant
or total as relevant). The uplift capacity from the static
formula (Annex G) can be approximately estimated
by ignoring end bearing but adding weight of pile
(buoyant or total as relevant). The safe uplift
capacity can be obtained by applying a factor of
safety 3. However, more reliance should be given to
that obtained from test loading as per good practice
[6-2(18)].
8.2.3.3 Lateral load capacity
A pile may be subjected to transverse forces for a
number of causes, such as wind, earthquake, water
current, earth pressure, effect of moving vehicles or
ships, plant and equipment, etc. The lateral load
carrying capacity of a single pile depends not only on
the horizontal subgrade modulus of the surrounding
soil but also on the structural strength of the pile shaft
against bending consequent upon the application of a
lateral load. While considering lateral load on piles,
the effect of other co-existent loads, including the axial
load on the pile, should be taken into consideration
for checking the structural capacity of the shaft. A
method for the determination of the depth of fixity of
piles for driven cast in-situ and depth of fixity, lateral
deflection and maximum moment for driven precast,
bored cast-m-sifw and bored precast piles required for
design is given in Annex H. Other accepted methods,
such as the method of Reese and Matlock or finite
element analysis using linear/non-linear springs to
represent the resistance of soil. A pile in a group of
three or more piles connected by a rigid cap shall be
designed considering as 'fixed head condition'. In caps
of single piles interconnected by ground beams in two
directions and for two piles by ground beams in a line
transverse to the common axis of the piles is also to be
considered as 'fixed head condition'. In all other
conditions the pile shall be designed by treating it 'free
head condition'.
NOTE — Because of limited information on horizontal modulus
of soil, and requirements in the theoretical analysis, it is
suggested that the adequacy of a design should be checked by
an actual field load test.
8.2.3.4 Raker piles
Raker piles are normally provided where vertical piles
cannot resist the required applied horizontal forces. In
the preliminary design, the load on a raker pile is
generally considered to be axial. The distribution of
load between raker and vertical piles in a group may
be determined graphically or by analytical methods.
Where necessary, due consideration should be given
to secondary bending induced as a result of the pile
cap movement, particularly when the cap is rigid.
Free-standing raker piles are subjected to bending
moments due to their own weight, or external forces
from other causes. Raker piles embedded in loose
fill or consolidating deposit may become laterally
loaded owing to the settlement of the surrounding
soil. In consolidating clay special precautions, like
provision of permanent casing, should be taken for
raker piles.
8.2.4 Spacing of Piles
The centre to centre spacing of a pile is considered
from two aspects as follows:
a) Practical aspects of installing the piles; and
b) The nature of the load transfer to the soil and
possible reduction in bearing capacity of a
group of piles thereby.
8.2.4.1 In the case of piles founded on a very hard
stratum and deriving their capacity mainly from end
bearing, the spacing will be governed by the
competency of the end bearing strata. The minimum
spacing in such cases shall be 2.5 times the diameter
of the shaft. In case of piles resting on rock, a spacing
of two times the diameter may be adopted.
8.2.4.2 Piles deriving their bearing capacity mainly
from friction shall be sufficiently apart to ensure that
the zones of soil from which the piles derive their
support do not overlap to such an extent that their
bearing values are reduced. Generally, the spacing in
such cases shall not be less than three times the
diameter of the shaft.
8.2.4.3 In the case of loose sand or filling, closer
spacing than in dense sand may be possible, in driven
piles since displacement during the piling may be
absorbed by vertical and horizontal compaction of the
strata. The minimum spacing in such strata may be
two times the diameter of the shaft.
NOTE — In the case of piles of non-circular cross-section, the
diameter of the circumscribijig circle shall be adopted.
8.2.5 Pile Grouping
In order to determine the bearing capacity of a group
of piles, a number of efficiency equations are in use.
However, it is very difficult to establish the accuracy
of these efficiency equations, as the behaviour of pile
group is dependent on many complex factors. It is
desirable to consider each case separately on its own
merits.
8.2.5.1 The bearing capacity of a pile group may be
either of the following:
24
NATIONAL BUILDING CODE OF INDIA
a) Equal to the bearing capacity of individual
piles multiplied by the number of piles in
group; or
b) It may be less.
The former holds true in the case of friction piles,
cast or driven into progressively stiffer materials or
in end-bearing piles. In friction piles in soft and clayey
soils, it is normally smaller. For driven piles in loose
sandy soils, the group value may be higher due to the
effect of compaction. In such a case, a load test should
be made on a pile from the group after all the piles
have been installed. The group capacity may then be
decided by taking into account the interference
effects. This would be done by multiplying the total
capacity of a pile group with the group efficiency
factor.
8.2.5.2 In the case of piles deriving their support
mainly from friction and connected by a rigid pile cap,
the group may be visualized to transmit load to the
soil, as if from a column of soil, enclosed by the piles.
The ultimate capacity of the group may be computed
following this concept, taking into account the
frictional capacity along the perimeter of the column
of soil as above and the end bearing of the said column
using the accepted principles of soil mechanics.
8.2.5.3 When the cap of the pile group is cast directly
on a reasonably firm stratum which supports the piles,
it may contribute to the bearing capacity of the group.
This additional capacity along with the individual
capacity of the piles multiplied by the number of piles
in the group shall not be more than the capacity worked
out as per 8.2.5.2.
8.2.5.4 When a moment is applied on the pile group
either from the superstructure or as a consequence
of unavoidable inaccuracies of installation, the
adequacy of the pile group in resisting the applied
moment should be checked. In the case of a single
pile subjected to moments due to lateral forces or
eccentric loading, beams may be provided to restrain
the pile caps effectively from lateral or rotational
movement.
8.2.5.5 In the case of a structure supported on a single
pile/group of piles, resulting in large variation in the
number of piles from column to column, it is likely,
depending on the type of subsoil supporting the piles,
to result in a high order of differential settlement. Such
high order of differential settlement may be either
catered for in the structural design or it may be suitably
reduced by judicious choice of variations in the actual
pile loadings. For example, a single pile cap may be
loaded to a level higher than that of a pile in a group in
order to achieve reduced differential settlement
between the adjacent pile caps supported on different
number of piles.
8.2.6 Factor of Safety
8.2.6.1 The factor of safety should be judiciously
chosen after considering the following:
a) The reliability of the value of the ultimate
bearing capacity of a pile,
b) The type of superstructure and the type of
loading, and
c) Allowable total/differential settlement of the
structure.
8.2.6.2 When the ultimate bearing capacity is
compound from either static formula or dynamic
formula, the factor of safety would depend on the
reliability of the formulae, depending on a particular
site and locality and the reliability of the subsoil
parameters employed in such computation. The
minimum factor of safety on static formula shall be
2.5. The final solution of a factor of safety shall take
into consideration the load settlement characteristics
of the structure as a whole on a given site.
8.2.6.3 The factor of safety for assessing the safe load
on piles from load test data should be increased in
unfavourable conditions where:
a) settlement is to be limited or unequal
settlement avoided as in the case of accurately
aligned machinery or a superstructure with
fragile finishings;
b) large impact or vibrating loads are expected;
c) the properties of the soil may be expected to
deteriorate with time; and
d) the live load on a structure carried by friction
piles is a considerable portion of the total and
approximates to the dead load in its duration.
8.2.7 Transient Loading
The maximum permissible increase over the safe load
of a pile as arising out of wind loading is 25 percent.
In the case of loads and moments arising out of
earthquake effects, the increase of safeload shall be as
given in Table 3.
8.2.8 Overloading
When a pile in a group, designed for a certain safe
load is found, during or after execution, to fall just
short of the load required to be carried by it, an overload
of up to 10 percent of the pile capacity may be allowed
on each pile. The total overloading on the group should
not be more than 10 percent of the capacity of the group
nor more than 40 percent of the allowable load on a
single pile.
8.2.9 Reinforcement
8.2.9.1 The design of the reinforcing cage varies
depending upon the driving and installation conditions,
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
25
the nature of the subsoil and the nature of load to be
transmitted by the shaft-axial, or otherwise. The
minimum area of longitudinal reinforcement (any type
or grade) within the pile shaft shall be 0.4 percent of
the sectional area calculated on the basis of the outside
area of the casing of the shaft.
8.2.9.2 The curtailment of reinforcement along the
depth of the pile, in general, depends on the type of
loading and subsoil strata. In the case of piles subjected
to compressive load only, the designed quantity of
reinforcement may be curtailed at an appropriate level
as per the design requirements. For piles subjected to
uplift load, lateral load and moments, separately or with
compressive loads, it may be necessary to provide
reinforcement for the full depth of pile. In soft clays
or loose sands, or where there is likelihood of danger
to green concrete due to driving of adjacent piles, the
reinforcement should be provided up to the full pile
depth, regardless of whether or not it is required from
uplift and lateral load considerations. However, in all
cases, the minimum reinforcement specified in 8.2.9.1
should be provided in the full length of the pile.
Piles shall always be reinforced with a minimum
amount of reinforcement as dowels, keeping the
minimum bond length into the pile shaft and with
adequate projection into the pile cap.
NOTE — In some cases the cage may lift at bottom or at the top
during withdrawal of casing. This can be minimized by making
the reinforcement 'IT shaped at the bottom and up to well
secured joints. Also the lifting 5 percent of the length should be
considered not to affect the quality of pile.
8.2.9.3 Clear cover to all main reinforcements in pile
shaft shall be not less than 50 mm. The laterals of a
reinforcing cage may be in the form of links or spirals.
The diameter and spacing of the same are so chosen as
to impart adequate rigidity to the reinforcing cage
during its handling and installation. The minimum
diameter of the links or spirals shall be 6 mm and the
spacing of the links or spirals shall be not less
than 150 mm.
8.2.10 Design of Pile Cap
8.2.10.1 The pile caps may be designed considering
that the reaction from any pile is concentrated at the
centre of the pile. The critical section for shear in
diagonal tension is taken at a distance equal to half the
effective depth of cap from the face of column/pedestal
or wall. For bending moment and shear for bond, the
critical section is taken at the face of column/pedestal
or wall for cap supporting a concrete column, pedestal
or wall; half way between the centre line and the edge
of the wall for caps under masonry walls and half-way
between the face of the column or pedestal and the
edge of the gusseted base for caps under gusseted bases.
In computing the external shear or the critical section,
the entire action of any pile of diameter D whose centre
is located DI2 or more outside the section shall be
assumed as producing no shear on the section. For
intermediate positions of the pile centre, the portion
of the pile reaction to be assumed as producing shear
on the section shall be based on straight-line
interpolation between full value at DI2 outside the
section and zero value at D/2 inside the section. Further,
design may be carried out as specified in Part 6
'Structural Design, Section 5 Concrete'.
8.2.10.2 The pile cap shall be deep enough to allow
for necessary anchorage of the column and pile
reinforcement and the minimum thickness shall
be 300 mm.
8.2.10.3 The pile cap should normally be rigid enough,
so that the imposed load could be distributed on the
piles in a group equitably.
8.2.10.4 In the case of a large cap, where differential
settlement may be imposed between piles under the
same cap, due consideration should be given to the
consequential moment.
8.2.10.5 The clear overhang of the pile cap beyond
the outer most pile in the group shall normally
be 100 mm to 150 mm, depending upon the pile
size.
8.2.10.6 The cap is generally cast over a 75 mm thick
levelling course of concrete. The clear cover for the
main reinforcement in the cap slab shall not be less
than 60 mm.
8.2.10.7 The pile should project 50 mm into the cap
concrete.
8.2.11 Grade Beams
8.2.11.1 The grade beams supporting the walls shall
be designed taking due account of arching effect due
to masonry above the beam. The beam with masonry
due to composite action behaves as a deep beam.
For the design of beams, a maximum bending moment
,2
of ^-> where w is uniformly distributed load per
metre run (worked out )ary considering a maximum
height of two storeys in structures with load bearing
walls and one storey in framed structures) and / is the
effective span in metres, will be taken if the beams are
supported during construction till the masonry above
it gains strength. The value of bending moment shall
,2
be increased to ^— •> if the beams are not supported.
For considering composite action, the minimum height
of wall shall be 0.6 times the beam span. The brick
strength should not be less than 3 N/mm 2 . For
concentrated and other loads which come directly over
the beam, full bending moment should be considered.
26
NATIONAL BUILDING CODE OF INDIA
8.2.11.2 The minimum overall depth of grade beams
shall be 150 mm. The reinforcement at the bottom
should be kept continuous and an equal amount may
be provided at top to a distance of a quarter span both
ways from pile centres. The longitudinal reinforcement
both at top and bottom should not be less than three
bars of 10 mm diameter mild steel (or equivalent
deformed steel) and stirrups of 6 mm diameter bars
should be spaced at a minimum of 300 mm spacing.
8.2.11.3 In expansive soils, the grade beams shall be
kept a minimum of 80 mm clear off the ground. In other
soils, beams may rest on ground over a levelling
concrete course of about 80 mm (see Fig. 6).
8.2.11.4 In the case of exterior beams over piles in
expensive soils, an edge projection of 75 mm thickness
and extending 80 mm into ground (see Fig. 6) shall be
provided on the outer side of the beam.
8.3 For detailed information on driven/bored cast
in- situ concrete piles regarding control of piling,
installation, defective pile and recording of data,
reference may be made to good practice [6-2(17)].
9 DRIVEN PRECAST CONCRETE PILES
9.1 Provisions of 8 except 8.2.9 shall generally apply.
9.2 Design of Piles
9.2.1 The design of pile section shall be such as to
ensure the strength and soundness of the pile against
lifting from the casting bed, transporting, handling,
driving stresses without damage.
9.2.2 Any shape having radial symmetry will be
satisfactory for precast piles. The most common cross-
sections used are square and octagonal or circular.
9.2.3 Where exceptionally long lengths of piles are
required, hollow sections may advantageously be used.
If the final conditions require a larger cross -sectional
area, the hollow sections may be filled with concrete
after driving in position.
9.2.4 Excessive whippiness in handling precast pile
may generally be avoided by limiting the length of pile
to a maximum of 50 times the least width.
9.2.5 Lifting and Handling Stresses
Stresses induced by bending in the cross-section of a
precast pile during lifting and handling may be
estimated just as for any reinforced concrete section
in accordance with relevant provisions of good practice
[6-2(13)]. The calculations with regard to moments
depending on the method of support during handling
will be as given below. Excessive whippiness in handling
precast pile may generally be avoided by limiting the
length of pile to a maximum of 50 times the least width.
Number of Location of Point of Bending
Points of Pick Support from in Moment to be
Up Terms of Length of Allowed for
Pile for Minimum Design
Moments
One
0.293 L
WL
23.3
Two
0.207 L
WL
46.6
Three
0.145 L, the middle
WL
point will be at the
"95"
centre
where
W =
Mass of pile in kg, and
L =
Length in metres.
During hoisting the pile will be suspended at one point
near the head and the bending moment will be the least
when it is pulled in a distance of 0.293 L, and the value
of bending moment will be:
WL
23.3
9.3 Reinforcement
9.3.1 The longitudinal reinforcement shall be provided
in precast reinforced concrete piles for the entire length.
All the main longitudinal bars shall be of the same
length with lap welded at joints and should fit tightly
into the pile shoe if there is one. Shorter rods to resist
local bending moments may be added, but the same
should be carefully detailed to avoid any sudden
discontinuity of the steel which may lead to cracks
during heavy driving. The area of the main longitudinal
reinforcement shall not be less than the following
percentages of the cross-sectional area of the piles:
a) For piles with length less than 30 times the
least width — 1.25 percent
b) For piles with length 30 to 40 times the least
width — 1.5 percent, and
c) For piles with length greater than 40 times
the least width — 2 percent.
9.3.2 The lateral reinforcement is of particular
importance in resisting the driving stresses induced in
the piles and should be in the form of hoops or links
and of diameter not less than 6 mm. The volume of
lateral reinforcement shall not be less than the
following:
a) At each end of the pile for a distance of about
3 times the least width — not less than 0.6
percent of the gross volume of that part of
the pile; and
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
27
m WIDTH OF WALL ^
r.'r-V'-^ .v.-*"
A^wJlU
ll «
//AW
50 mm THICK CONCRETE
SLAB OR BRICK ON EDGE
8
§
^ WIDTH OF WALL fc
75
/7AVV
-50 mm THICK CONCRETE
SLAB OR BRICK ON EDGE
INTERIOR BEAM
EXTERIOR BEAM
6A BEAMS IN EXPANSIVE SOILS
./ WIDTH OF WALL
GL
1
c
E
'.
•■**
■••••?■.'•:• ■•■ r> >*•■•■/.•.„
//AV
* >-MAY BE ELIMINATED
s
':"
/^ IN CASE OF VERTICAL
CUTS
■
1
*'''' - '«• ' •• '^- •' "■*'•"*••;«•'
s 1
id-
LEVELLING COURSE
7
6B BEAMS IN NON - EXPANSIVE SOILS
All dimensions in millimetres.
Fig. 6 Typical Sections of Grade Beams
b) In the body of the pile — not less than
0.2 percent of the gross volume of the pile.
The spacing shall be such as to permit free flow of
concrete around it. The transition between the close
spacing of lateral reinforcement near the ends and the
maximum spacing shall be gradually over a length of
3 times the least width of the pile.
9.3.3 The cover of concrete over all the reinforcement,
including ties, should not be less than 40 mm. But
where the piles are exposed to sea-water or water
having other corrosive content, the cover should be
nowhere less than 50 mm. Cover should be measured
clear from the main or longitudinal reinforcement.
NOTE — Where concrete of the pile is liable to be exposed to
the attack of sulphates and chlorides present in the ground water,
the piles may be coated with a suitable material.
9.3.4 Piles should be provided with flat or pointed co-
axial shoes if they are driven into or through ground,
such as rock, coarse gravel, clay with cobbles and other
soils likely to damage the concrete at the tip of the
pile. The shoe can be of steel or cast iron. In uniform
clay or sand, the shoe may be omitted.
Where jetting is necessary for concrete piles, a jet tube
may be cast into the pile, the tube, being connected to
the pile shoe which is provided with jet holes.
Generally, a central jet is inadvisable, as it is liable to
become choked. At least Jwo jet holes will be necessary
on opposite sides of the shoe, four holes giving best
results. Alternatively, two or more jet pipes may be
attached to the sides of the pile.
9.4 For detailed information regarding casting and
curing, storing and handling, control of pile driving
and recording of data, reference may be made to good
practice [6-2(20)].
10 BORED PRECAST CONCRETE PILES
10.1 Provisions of 9 except 93 shall generally apply.
10.2 For grouting the space around the pile, the precast
28
NATIONAL BUILDING CODE OF INDIA
pile should be provided with a central duct/hole or
suitable jet holes to pump the grouting material. The
bottom end of the pile shall have proper arrangements
for flushing/cleaning for grouting.
10.3 Reinforcement
The longitudinal reinforcement shall be provided in
for the entire length preferably of high yield strength
to withstand the handling stresses to the extent to meet
requirement as given in 9.2.5. All the main longitudinal
bars shall be of the same length. The area of the main
longitudinal reinforcement of any type and grade shall
not be less than 0.4 percent of the cross-section area
of the piles or as required to cater for handling stresses
whichever is greater. The lateral reinforcement shall
be links or spirals preferably of not less than 6 mm
diameter bars. The cover of concrete over all the
reinforcement including bending wire should not be
less than 40 mm, but where the piles are exposed to
the sea-water or water having other corrosive contents
the cover should be no where less than 50 mm. A thin
gauge sheathing pipe of approximately 40 mm
diameter may be attached to the reinforcement cage,
in case of solid piles, to form the central duct for
pumping grout to the bottom of the bore.
10.4 For detailed information regarding casting and
curing, storing and handling, control of pile installation
and recording of data, reference may be made to good
practice [6-2(21)].
11 UNDER-REAMED PILES
11.0 General
Under-reamed piles are bored cast in-situ and bored
compaction concrete types having one or more bulbs
formed by enlarging the borehole for the pile stem.
These piles are suited for expansive soils which are
often subjected to considerable ground movements due
to seasonal moisture variations. These also find wide
application in other soil strata where economics are
favourable. When the ground consists of expansive soil,
for example, black cotton soils, the bulb of under-
reamed pile provide anchorage against uplift due to
swelling pressure, apart from the increased bearing,
provided topmost bulb is formed close to or just below
the bottom of active zone. Negative slopes may not be
stable in certain strata conditions, for example, in pure
sands (clean sands with fines less than five per cent)
and very soft clayey strata having N of SPT less than
2 (undrained shear strength of less than 12.5 kN/m 2 ).
Hence formation of bulb(s) in such strata is not
advisable. In subsoil strata above water table, the
maximum number of bulbs in underreamed pile should
be restricted to four. In the strata such as clay, silty
clay and clayey silt with high water table where sides
of bore hole stand by itself without needing any
stabilization by using drilling mud or otherwise, the
maximum number of bulbs in under-reamed piles
should be restricted to two. In strata, for example, clayey
sand, silty sand and sandy silt with high water table
where bore hole needs stabilization by using drilling
mud, under-reamed piles with more than one bulb shall
not be used. In loose to medium pervious strata such
as clayey sand, silty sand and sandy silt strata,
compaction under-reamed piles can be used as the
process of compaction, increases the load carrying
capacity of piles. From practical considerations,
under-reamed piles of more than 10 m depth shall not
be used without ensuring their construction feasibility
and load carrying capacity by initial load tests in
advance. In view of additional anchorage available
with the provision of bulbs, under-reamed piles can
be used with advantage to resist uplift loads.
11.1 Materials
11.1.1 Provisions of 8.1 shall generally apply.
11.2 Design Considerations
11.2.1 General
Under-reamed pile foundation shall be designed in such
a way that the load from the structure they support can
be transmitted to the soil without causing failure of
soil or failure of pile material and without causing
settlement (differential or total) under permanent
transient loading as may result in structural damage
and/or functional distress {see Fig. 7).
11.2.1.1 In deep deposits of expansive soils the
minimum length of piles, irrespective of any other
considerations, shall be 3.5 m below ground level. If
the expansive soil deposits are of shallow depth and
overlying on non-expansive soil strata of good bearing
or rock, piles of smaller length can also be provided.
In recently filled up grounds or other strata or poor
bearing the piles should pass through them and rest in
good bearing strata.
11.2.1.2 The minimum stem diameter of under-reamed
pile can be 200 mm up to 5 ra* depth in dry conditions,
that is strata with low water table. The minimum stem
diameter for piles up to 5 m depth in strata with high
water table within pile depth, shall be 300 mm for
normal under-reamed pile and 250 mm for compaction
under-reamed pile. For piles of more than 5 m depth,
the minimum diameter in two cases shall be 375 mm
and 300 mm respectively. The minimum diameter of
stem for strata consisting of harmful constituents, such
as sulphates, should also be 375 mm.
11.2.1.3 The diameter of under-reamed bulbs may
vary from 2 to 3 times the stem diameter, depending,
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
29
GL
JL
xSTIRRUPS
STIRRUPS
FIRST BULB
BORING LEVEL FOR
MAKING FIRST BULB
SECOND/LAST
BULB
COVER
75 TO 100
01
02
X
Q Q.
<
= 45° (APPROX.)
= 30° - 45° (APPROX)
= NORMALLY 2.5 D
7A SECTION OF SINGLE -
UNDER - REAMED PILE
7B SECTION OF MULTI-
UNDER-REAMED PILE
All dimensions in millimetres.
Fig. 7 Typical Details of Bored Cast in-situ Under-Reamed Pile Foundation
upon the feasibility of construction and design
requirements. In bored cast in-situ under- reamed piles
and under-reamed compaction piles, the bulb diameter
shall be normally 2.5 and 2 times the stem diameter
respectively.
11.2.1.4 For piles of up to 300 mm diameter, the
spacing of the bulbs should not exceed 1 .5 times the
diameter of the bulb. For piles of diameter greater than
300 mm, spacing can be reduced to 1 .25 times the bulb
diameter.
11.2.1.5 The topmost bulb should be at a minimum
depth of two times the bulb diameter. In expansive
soils it should also be not less than 2.75 m below
ground level. The minimum clearance below the
underside of pile cap embedded in the ground and
the bulb should be a minimum of 1.5 times the bulb
diameter.
11.2.1.6 Under-reamed piles with more than one bulb
are not advisable without ensuring their feasibility in
strata needing stabilization of bore holes by drilling mud.
The number of bulbs in the case of bored compaction
piles should also not exceed one in such strata.
11.2.1.7 Under-reamed batter piles without lining in
dry conditions, that is, strata with low water table can
be constructed with batter not exceeding 15°.
11.2.2 Safe Load
Safe load on a pile can be determined:
a) by calculating the ultimate load from soil
properties and applying a suitable factor of
safety as given in Annex J;
b) by load test on pile as good practice [6-2(18)];
and
c) from safe load tables.
30
NATIONAL BUILDING CODE OF INDIA
11.2.2.1 Load test and non-destructive testing
Provisions of 8.2.1.4 and 8.2.1.5 shall generally apply.
11.2.2.2 In the absence of detailed sub-soil
investigations and pile load tests for minor and less
important structures, a rough estimate of safe load on
piles may be made from the Safe Load Table in
accordance with good practice [6-2(22)].
11.2.3 Negative Skin Friction or Dragdown Force
Provisions of 8.2.2 shall generally apply subject to the
condition that the under-reamed bulb is provided below
the strata susceptible to negative skinfriction.
11.2.4 Structural Capacity
Provisions of 8.2.3 shall generally apply except that
the under-reamed pile stem is designed for axial capacity
as a short column. Under-reamed piles under lateral
loads and moments tend to behave more as rigid piles
due the presence of bulbs and therefore the analysis
can be done on rigid pile basis. Nominally reinforced
long single bulb piles which are not rigid may be
analyzed as per the method given in Annex H or as
per other accepted methods.
11.2.5 Spacing
11.2.5.1 Generally the centre to centre spacing for
bored cast in-situ under-reamed piles in a group should
be two times the bulb diameter (2 D u ). It shall not be
less than 1 .5 D u . For under-grade beams, the maximum
spacing of piles should generally not exceed 3 m. In
under-reamed compaction piles, generally the spacing
should not be less than 1 .5 D .If the adjacent piles are
of different diameter, an aveage value of bulb diameter
should be taken for spacing.
11.2.6 Group Efficiency
For bored cast in-situ under-reamed piles at a usual
spacing of 2 £> u , the group efficiency will be equal to
the safe load of an individual pile multiplied by the
number of piles in the group. For piles at a spacing of
1 .5 £> u , the safe load assigned per pile in a group should
be reduced by 10 percent.
In under-reamed compaction piles, at the usual spacing
of 1.5 £> u , the group capacity will be equal to the safe
load on an individual pile multiplied by the number of
piles in the group.
11.2.7 Transient and Overloading
Provisions of 8.2.7 and 8.2.8 shall generally apply.
11.2.8 Reinforcement
11.2.8.1 The minimum area of longitudinal
reinforcement (any type or grade) within the pile shaft
shall be 0.4 percent of the sectional area calculate on
the basis of outside area of the shaft or casing if used.
Reinforcement is to be provided in full length and
further a minimum of 3 bars of 10 mm diameter mild
steel or three 8 mm diameter high strength steel bars
shall be provided. Transverse reinforcement shall not
be less than 6 mm diameter at a spacing of not more
than the stem diameter or 300 mm, whichever is less.
In under-reamed compaction piles, a minimum number
of four 12 mm diameter bars shall be provided. For
piles of lengths exceeding 5 m and of 375 mm
diameter, a minimum number of six 12 mm diameter
bars shall be provided. For piles exceeding 400 mm
diameter, a minimum number of six 12 mm diameter
bars shall be provided. The circular stirrups for piles
of lengths exceeding 5 m and diameter exceeding
375 mm shall be minimum 8 mm diameter bars.
For piles in earthquake prone areas, a minimum number
of six bars of 10 mm diameter shall be provided. Also
transverse reinforcement in the form of stirrups or
helical should be at 150 mm centre-to-centre in top
few metre depth.
11.2.8.2 The minimum clear cover over the
longitudinal reinforcement shall be 40 mm. In
aggressive environment of sulphates etc, it may be
increased to 75 mm.
11.2.9 The design of pile cap and grade beams shall
conform to the requirements specified in 8.2.10 and
8.2.11 respectively.
11.2.10 For detailed information on under-reamed
piles regarding control of pile, installation, reference
may be made to good practice [6-2(22)].
12 TIMBER PILES
12.1 Materials
12.1.1 Timber
The timber shall have the following characteristics:
a) Only structural timber shall be used for piles
(see Part 6 'Structural Design, Section 3 Timber
and Bamboo, 3 A Timber');
b) The length of an individual pile shall be:
1) the specified Jength ± 300 mm for piles
up to and including 1 2 m in length, and
2) the specified length ± 600 mm for piles
above 12 m in length;
c) The ratio of heartwood diameter to the pile
butt diameter shall be not less than 0.8;
and
d) Piles to be used untreated shall have as little
sapwood as possible.
12.2 Design Considerations
12.2.1 General — See 8.0.
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
31
12.2*2 Soil Resistance — See 8.2.1.
12.2.3 Structural Capacity
The pile shall have the necessary structural strength to
transmit the load imposed on it to the soil. Load tests
shall be conducted on a single pile or preferably on a
group of piles. For compaction piles, test should be done
on a group of piles with their caps resting on the ground
as good practice [6-2(18)]. If such test data is not
available, the load carried by the pile shall be determined
by the Engineering News formula (see Note).
NOTE — For timber piles, the load carried shall be determined
by the Engineering News formula given below. Care shall be
taken that while counting the number of blows, the head of the
timber pile is not broomed or brushed and in case of interrupted
driving counting shall be done after 300 mm of driving.
For piles driven with drop hammer,
P =
160 WH
S + 25
For piles driven with single-acting steam hammer,
P =
160 WH
S + 2.5
where
P
W
H
S
Safe load on pile in kN,
Weight of monkey in kN,
Free fall of monkey in m, and
Penetration of pile in mm to be taken as the average
of the last three blows.
12.2.4 For detailed information on timber piles
regarding spacing, classification, control of pile
driving, storing and handling, reference may be made
to good practice [6-2(23)].
13 OTHER FOUNDATIONS
13.1 Pier Foundations
13.1.1 Design Considerations
13.1.1.1 General
The design of concrete piers shall conform to the
requirements for columns specified in Part 6 'Structural
Design, Section 5 Concrete'. If the bottom of the pier
is to be belled so as to increase its load carrying
capacity, such bell shall be at least 300 mm thick at its
edge. The sides shall slope at an angle of not less than
60° with the horizontal. The least permissible
dimensions shall be 600 mm, irrespective of the pier
being circular, square or rectangular. Piers of smaller
dimensions if permitted shall be designed as piles
(see 8 and 9).
13.1.1.2 Plain concrete piers
The height of the pier shall not exceed 6 times the least
lateral dimension. When the height exceeds 6 times
the least lateral dimension, buckling effect shall be
taken into account, but in no case shall the height
exceed 12 times the least lateral dimension.
When the height exceeds 6 times the least lateral
dimension, the deduction in allowable stress shall be
given by the following formula:
/c'=/c
1.3-
H
20D
where
/;
/c
H
D
Reduced allowable stress,
Allowable stress,
Height of pier, and
Least lateral dimension.
NOTE — The above provision shall not apply for piers where
the least lateral dimension is 1.8 m or greater.
13.1.1.3 Reinforced concrete piers
When the height of the pier exceeds 1 8 times its least
dimension, the maximum load shall not exceed:
P' = P
1.5-
H
36D
where
P r = Permissible load;
P = Permissible load when calculated as axially
loaded short column,
H = Height of the pier measured from top of bell,
if any, to the level of cut-off of pier; and
D = Least lateral dimension.
13.2 Design of foundation units not already covered
by this section, such as well foundations, machine
foundations, shell foundations, etc, may be designed
and constructed in accordance with good practice
[6-2(24)].
14 GROUND IMPROVEMENT
In poor and weak subsoil?, the design of conventional
shallow foundation for structures and equipment may
present problems with respect to both sizing of
foundation as well as control of foundation settlements.
A viable alternative in certain situations, developed
over the recent years is to improve the subsoil to an
extent such that the subsoil would develop an adequate
bearing capacity and foundations constructed after
subsoil improvement would have resultant settlements
within acceptance limits. Selection of ground
improvement techniques may be done in accordance
with good practice [6-2(25)].
Use of suitable geo-synthetics/geo-textiles may be
made in an approved manner for ground improvement,
where applicable; see also good practice [6-2(26)].
32
NATIONAL BUILDING CODE OF INDIA
ANNEX A
(Clause 7.3.1.11)
DETERMINATION OF MODULUS OF ELASTICITY (E s )
AND POISSON'S RATIO (M)
A-l DETERMINATION OF MODULUS OF
ELASTICITY (E s )
A-Ll The modulus of elasticity is a function of
composition of the soil, its void *ratio, stress history
and loading rate. In granular soils it is a function of
the depth of the strata, while in cohesive soil it is
markedly influenced by the moisture content. Due to
its great sensitivity to sampling disturbance, accurate
evaluation of the modulus in the laboratory is extremely
difficult. For general cases, therefore, determination
of the modulus may be based on field tests (A-2).
Where properly equipped laboratory and sampling
facility is available, E s may be determined in the
laboratory (see A-3).
A-2 FIELD DETERMINATION
A-2.1 The value of E s shall be determined from plate
load test in accordance with good practice [6-2(8)].
where
q = Intensity of contact pressure,
B = Least lateral dimension of test plate,
s - Settlement,
ji — Poisson's ratio, and
/ w = Influence ratio
= 0.82 for a square plate.
A-2.1.1 The average value of E s shall be based on a
number of plate load tests carried out over the area,
the number and location of the tests, depending upon
the extent and importance of the structure.
A-2.1.2 Effect of Size
In granular soils the value of £. corresponding to the
size of the raft shall be determined as follows:
where B p B represent sizes of foundation and plate
and E is the modulus determined by the plate load
test.
A-2.2 For stratified deposits or deposits with lenses
of different materials, results of plate load test will be
unreliable and static cone penetration tests may be
carried out to determine £ s .
A-2.2.1 Static cone penetration tests shall be carried
out in accordance with good practice [6-2(1)], Several
tests shall be carried out at regular depth intervals up
to a depth equal to the width of the raft and the results
plotted to obtain an average value of £ s .
A-2.2.2 The value of £ s may be determined from the
following relationship:
E =2C
kd
where
g f +gp)
2 * f .
C kd = Cone resistance in kN/m 2 .
A3 LABORATORY DETERMINATION OF E s
A-3.1 The value of £, shall be determined by
conducting triaxial test in the laboratory in accordance
with good practice [6-2(4)] on samples collected with
least disturbances.
A-3.2 In the first phase of the tri-axial test, the
specimen shall be allowed to consolidate fully
under an all-round confining pressure equal to the
vertical effective overburden stress for the specimen
in the field. In the second phase, after equilibrium
has been reached, further drainage shall be prevented
and the deviator stress shall be increased from zero
value to the magnitude estimated for the field
loading condition. The deviator stress shall then be
reduced to zero and the cycle of loading shall be
repeated.
A-3.3 The value of E s shall be taken as the tangent
modulus at the stress level equal to one-half the
maximum deviator stress applied during the second
cycle of loading.
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
33
ANNEX B
(Clause 7.3.1.11)
DETERMINATION OF MODULUS OF SUBGRADE REACTION
B-l GENERAL
B-l.l The modulus of subgrade reaction (k) as
applicable to the case of load through a plate of size
300 mm x 300 mm or beams 300 mm wide on the soils
is given in Table 6 for cohesionless soils and in Table 7
for cohesive soils. Unless more specific determination
of k is done (see B-2 and B-3) these values may be
used for design of raft foundation in cases where the
depth of the soil affected by the width of the footing
may be considered isotropic and the extra-polation of
plate load test results is valid.
B-2 FIELD DETERMINATION
B-2.1 In cases where the depth of the soil affected by
the width of the footing may be considered as isotropic,
the value of k may be determined in accordance with
good practice [6-2(27)]. The test shall be carried out
with a plate of size not less than 300 mm.
B-2.2 The average value of k shall be based on a
number of plate load tests carried out over the area,
the number and location of the tests depending upon
the extent and importance of the structure.
B-3 LABORATORY DETERMINATION
of different materials, evaluation of k from plate load
test will be unrealistic and its determination shall be
based on laboratory tests [see 6-2(4)] .
B-3. 2 In carrying out the test, the continuing cell
pressure may be so selected as to be representative of
the depth of the average stress influence zone (about
0.5 B to B).
B-3.3 The value of k shall be determined from the
following relationship:
k = 0.65 x
{ EB^
EI
1
(1-AO*
Table 6 Modulus of Subgrade Reaction (k) for Cohesionless Soils
{Clause B-l.l)
Soil Characteristic
N)
f-
i] Modulus of Subgrade
kN/m 3
Reaction (k)
Relative Density
U)
Standard Penetration Test Value (
(Blows per 300 mm)
(2)
For Dry or Moist State
(3)
For Submerged State
(4)
Loose
Medium
Dense
pply
<10 15 000
10 to 30 15 000 to 47 000
30 and over 47 000 to 180 000
to a square plate 300 mm x 300 mm or beams 300 mm wide.
9 000
9 000 to 29 000
29 000 to 108 000
l) The above values a
Table 7 Modulus of Subgrade Reaction (k) for Cohesive Soils
(Clause B-l.l)
Soil Characteristic
1J Modulus of Subgrade Reaction (it)
-*»^.
kN/m 3
Consistency
unconfined Compressive Strength,
kN/m 2
(1)
(2)
(3)
Stiff
100 to 200
27 000
Very Stiff
200 to 400
27 000 to 54 000
Hard
400 and over
i square plate 300 mm x 300 mm. The above values are
based
on the
54 000 to 108 000
1} The values apply to i
assumption that the average loading
intensity does not exceed half the ultimate bearing capacity.
34
NATIONAL BUILDING CODE OF INDIA
where
B-4 CALCULATIONS
E s = Modulus of elasticity of soil (see Annex A),
E = Young's modulus of foundation material,
ft = Poisson's ratio of soil,
/ = Moment of inertia of the foundation, and
B = Width of the footing.
When the structure is rigid (see Annex C), the average
modulus of subgrade reaction may also be determined
as follows:
Jt=-
Average contact pressure
Average settlement of the raft
ANNEX C
(Clauses 7.3.4.1, 7.3.4.2 and B-4)
RIGIDITY OF SUPERSTRUCTURE AND FOUNDATION
C-l DETERMINATION OF THE RIGIDITY OF
THE STRUCTURE
C-l.l The flexural rigidity EI of the structure of any
section may be estimated according to the relation
given below (see also Fig. 8)
EI^
E l I,b
2H 2
+ ZEJ h
1 + -
where
E,
= Modulus of elasticity of the infilling
material (wall material) in kN/m 2 ,
/. = Moment of inertia of the infilling in m 4 ,
b = Length or breadth of the structure in the
direction of bending in m,
H = Total height of the infilling in m,
E 2 = Modulus of elasticity of the frame material
in kN/m 2 ,
7 b = Moment of inertia of the beam in m 4 ,
b /
/ = Spacing of the columns in m,
h a = Length of the upper column in m,
h. = Length of the lower column in m,
■•-'i
I u = Moment of inertia of the upper column
in m 4 ,
/ = Moment of inertia of the lower column
in m 4 , and
7 f = Moment of inertia of the foundation beam
or raft in m 4 .
NOTE — The summation is to be done over all the
storeys including the foundation beam or raft. In the
case of the foundation, /' replaces I' b and / becomes
zero, whereas for the topmost beam /' u becomes zero.
FOUNDATION RAFT
Fig. 8 Determination of Rigidity of Structure
C-2 RELATIVE STIFFNESS FACTOR, K
C-2.1 Whether a structure behaves as rigid or flexible
depends on the relative stiffness of the structure and
the foundation soil. This relation is expressed by the
relative stiffness factor K given below:
EI
a) For the whole structure, K = —
EJba
T7 V^V
b) For rectangular rafts, K = .^ _
^ j
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
35
c) For circular rafts, K =
12 E
V
2R
where
EI = Flexural rigidity of the structure over the
length (a) in kN/m 2 ,
£ = Modulus of compressibility of the
foundation soil in kN/m 2 ,
b - Length of the section in the bending axis in m,
a = Length perpendicular to the section under
investigation in m,
d = Thickness of the raft or beam in m, and
R = Radius of the raft in m.
C-2.1.1 For K> 0.5, the foundation may be considered
as rigid.
C-3 DETERMINATION OF CRITICAL COLUMN
SPACING
C-3.1 Evaluation of the characteristics X is made as
follows:
where
k
B
E
k =
( kB V
4EJ
Modulus of subgrade reaction in kN/m 3 for
footing of width B in m (see Annex B),
Width of raft B in m,
Modulus of elasticity of concrete in kN/m 2 ,
and
Moment of inertia of raft in m 4 .
ANNEX D
(Clause 7.3.4.1)
CALCULATION OF PRESSURE DISTRIBUTION BY CONVENTIONAL METHOD
D-l DETERMINATION
DISTRIBUTION
OF PRESSURE
D-l.l The pressure distribution (q) under the raft shall
be determined by the following formula:
£„ = e„—-
where
e\ e\I
x' y'
q = —±—r~y±^ L x
A /' V
Q = Total vertical load on the raft,
A = Total area of the raft,
[, I' = Eccentricities and moments of inertia
about the principal axes through the
centroid of the section, and
x t y= Co-ordinates of any given point on
the raft with respect to the x and y
axes passing through the centroid of
the area of the raft.
x' y, x' y
equations:
/:
/; = /,-
where
/ x , / = Moment of inertia of the area of the raft
respectively about the x and y axes through
the centroid,
/ = fxy dA for the whole area about x and y
axes through the centroid, and
e x , e y = Eccentricities in the x and y directions of
the load from the centroid.
For a rectangular raft, the equation simplifies to:
? = •
1±
12^ y y t 12 ex
e' may be calculated from the following where
a and b = the dimensions of the raft in the x and y
directions respectively.
NOTE — If one or more of the values of (q) are nagative as
calculated by the above formula, it indicates that the whole area
of foundation is not subject to pressure and only a part of the
area is in contact with the soil, and the above formula will still
hold good, provided the appropriate values of 7 x , / , / , e x and e ,
are used with respect to the area in contact with the soil instead
of the whole area.
36
NATIONAL BUILDING CODE OF INDIA
ANNEX E
(Clause 7.3.4.2)
CONTACT PRESSURE DISTRIBUTION AND MOMENTS BELOW
FLEXIBLE FOUNDATION
El CONTACT PRESSURE DISTRIBUTION
E-l.l The distribution of contact pressure is assumed
to be linear with the maximum value attained under
the columns and the minimum value at mid span.
E-1.2 The contact pressure for the full width of the
strip under an interior column load located at a point i
can be determined as (see Fig. 9 A):
5 P 48 M.
9A MOMENT AND PRESSURE DISTRIBUTION
AT INTERIOR COLUMN
9B PRESSURE DISTRIBUTION OVER
AN INTERIOR SPAN
F
/i /
•i
C
/ 1/2 / 1/2 __
' 1
;
'
1
i
///^
1 *
4e I
I |
I
9C MOMENT AND PRESSURE DISTRIBUTION AT EXTERIOR COLUMNS
Fig. 9 Moment and Pressure Distribution at Columns
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
37
where
J = Average length of adjacent span (m),
P. = Column load at point i, and
M. = Moment under an interior columns loaded
ati.
E-1.3 The minimum contact pressure for the full width
of the strip at the middle of the adjacent spans can be
determined as (see Fig. 9A and 9B).
p^=^p {
P m =2P,
v ' /
P,
1. 1
-Pi
'P
'P
= Pmr + An
E-1.4 If E-2.3 (a) governs the moment under the
exterior columns, contact pressures under the exterior
columns and at end of strip can be determined as (see
Fig. 9C):
P,=
E-1.5 If E-2.3 (b) governs the moment under the
exterior columns, the contact pressures are determined
as (see Fig. 9C):
4/> e
6M e
+ 5-
C
-PJi
) — -
C+l,
3M e
P\
4 p -p I
p =p = ^ ^m r
E-2 BENDING MOMENT DIAGRAM
E-2.1 The bending moment under an interior column
located at i (see Fig. 9A) can be determined as:
M=^-(024XT + 0A6)
E-2.2 The bending moment at mid span is obtained
as (see Fig. 9A):
M =M +M.
m o i
where
M q = Moment of simply supported beam
- (J ^-[p,(0+4p m+Pi (r)]
4o - J
M. = Average of negative moments M. at each
end of the bay.
E-2.3 The bending moment M e under exterior columns
can be determined as the least of (see Fig. 9C):
a) M el = — M0.13A/,+1.06AC-0.50)
e2 (4C + / f ) 2
ANNEX F
(Clause 7.3.4.2)
FLEXIBLE FOUNDATION — GENERAL CONDITION
F-l CLOSED FORM SOLUTION OF ELASTIC
PLATE THEORY
F-l.l For a flexible raft foundation with non-uniform
column spacing and load intensity, solution of the
differential equation governing the behaviour of plates
on elastic foundation (Winkler Type) gives radial
moment (M.) tangential moment (M) and deflection
(w) at any point by the following expressions:
M r
M.
_P
4
P
4
Mi)-^y
m
(f)
fiz 4 (l)+(i-^)
a)
w
PL
AD
•Z,
(i)
where
P - Column load,
r = Distance of the point under investigation
from column load along radius, and
L - Radius of effective stiffness
k
where
k - Modulus of subgrade reaction for footing
of width 5,
D - Flexural rigidity of the foundation,
2
P =
Et
12(1-M 2 )
38
NATIONAL BUILDING CODE OF INDIA
t = Raft thickness,
E - Modulus of elasticity of the foundation
material,
A* = Possion's ratio of the foundation material,
and
Mi)-
Mf)-
= Functions of shear, moment and
deflection (see Fig. 10)
F-1.2 The radial and tangential moments can be
converted to rectangular co-ordinates:
M x = M. cos 2 + M t sin 2
M v = M r s'm 2 (f) + M { cos 2 (p
where
(j) = Angle with x-axis to the line jointing origin
to the point under consideration.
F-1.3 The shear Q per unit width of raft can be
determined by:
^4 [l) = function for shear (see Fig. 10).
F-1.4 When the edge of the raft is located within the
radius of influence, the following corrections are to be
applied. Calculate moments and shears perpendicular
to the edge.of the raft within the radius of influence,
assuming the raft to be infinitely large. Then apply
opposite and equal moments and shears on the edge of
the mat. The method for beams on elastic foundation
may be used.
F-1.5 Finally, all moments and shears calculated for
each individual column and wall are superimposed to
obtain the total moment and shear values.
CO
z
o
o
2
CO
LU
3
Fig.
10 Functions for Shear Moment
and Deflection
ANNEX G
(Clauses 8.2.1.2 and 8.2.3.2)
LOAD CARRYING CAPACITY — STATIC FORMULA
G-l PILES IN GRANULAR SOILS
G-l.l The ultimate bearing capacity (Q ) of piles in
granular soils is given by the following formula:
Q u =A p (y 2 D.7.N y +P D .N q ) + iK.P Di .t a n8.A i
i=l
where
A = Cross-sectional area of pile toe in m 2 ;
D = Stem diameter in m;
7 = Effective unit w r eight of soil at pile toe in
kN/m 3 ;
P D = Effective overburden pressure at pile toe
in kN/m 2 ;
N ,N = Bearing capacity factors and depending
upon the angle of internal friction 0, at toe;
X = Summation for n layers in which pile is
installed;
K = Coefficient of earth pressure;
P Di = Effective overburden pressure in kN/m 2 for
the ith layer, where / varies from 1 to n;
8 = Angle of wall friction between pile and soil,
in degrees (may be taken equal to0); and
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
39
A si = Surface area of pile stem in m 2 in the ith
layer, where i varies from 1 to n,
NOTES
1 For N y factors refer to good practice [6-2(7)].
2 N factor will depend, apart from nature of soil on the type of
pile and the method of its construction and the values are given
in Fig. 1 1 and Fig. 1 2 for bored and driven piles respectively.
3 The earth pressure coefficient K depends on the nature of
soil strata, type of pile and the method of its construction. For
driven piles in loose to medium sands, A' values of 1 to 3 should
be used. For bored piles, k values can be taken between 1 and 2.
4 The angle of wall friction may be taken equal to the angle of
shear resistance of soil.
5 In working out pile capacities using static formula, for piles
larger than 15 to 20 pile diameters, the maximum effective
overburden at the pile tip should correspond to pile length equal
to 15 to 20 times of the diameters.
G-2 PILES IN COHESIVE SOILS
G-2.1 The ultimate bearing capacity of piles (QJ in
cohesive soil is given by the following formula:
Q = A N .C+ aC A
where
A = Cross-sectional area of pile toe in m 2 ,
TV = Bearing capacity factor usually taken as 9,
C = Average cohesion at pile tip in kN/m 2 ,
a ~ Reduction factor,
C = Average cohesion throughout the length of
pile in kN/m 2 , and
A s = Surface area of pile shaft in m 2 .
NOTES
1 The following values of a may be taken, depending upon
the consistency of the soils:
Consistency
N Value
Value
>ofa
f
-\
Bored piles
Driven cast
in-situ piles
0)
(2)
(3)
(4)
Soft to very soft
<4
0.7
1
Medium
4 to 8
0.5
0.7
Stiff
8 to 15
0.4
0.4
Stiff to hard
>15
0.3
0.3
2 a) Static formula may be used as a guide only for bearing
capacity estimates. Better reliance may be put on load
test on piles,
b) For working out safe load, a minimum factor of safety
2.5 should be used on the ultimate bearing capacity
estimated by static formulae.
3 In case of soft to very soft soils which are not sensitive, the
value of a can be taken up to 1.
G-3 When full static penetration data is available for
the entire depth, the following correlations may be used
as a guide for the determination of shaft resistance of
a pile:
Type of Soil
Clays and peats where q c < 1
Clays
Silty clays and silty sands
Sands
Coarse sands and gravels
Local Side Friction
/.
3 J * 1
- </ s < ^
2.5 2.5
2s
3
— </ s < —
10 2.5
& </ s < ^
10 10
/.< ^
15
where
q c = Static point resistance in N/mm 2 , and
/ = Local side friction in N/mm 2 .
For non-homogeneous soils, the ultimate point bearing
capacity may be calculated using the following
relationships:
4c0 + ftl
+ 4c2
4u=-
where
q u = Ultimate point bearing capacity,
q cQ = Average static cone resistance over a depth
of 2 d below the base level of the pile,
q - Minimum static cone resistance over the
same 2 d below the pile tip,
q c2 = Average of the minimum cone resistance
values in the diagram over a height of 8 d
above the base level of the pile, and
d = Diameter of the pile base or the equivalent
diameter for a non-circular cross-section.
G-3.1 The correlation between standard penetration
test value W and static point resistance q c (in N/mm 2 )
given below may be used for working out the shaft
resistance and skin friction of piles:
Soil type qJN
Clays, silts, sandy silts and slightly 0.2
cohesive silt-sand mixtures
Clean fine to medium sands and 0.3-0.4
slightly silty sands
Coarse sands and sands with little 0.5-0.6
gravel
Sandy gravels and gravel 0.8-0.10
40
NATIONAL BUILDING CODE OF INDIA
25 30 35 40 45
ANGLE OF INTERNAL FRICTION,
Fig. 11 Bearing Capacity Factor, N q for Bored Piles
J
/
z
O
O 100
/
< w
UL
o
<
RING CAP
8
<
ill
CD
10
20 25 30 35 40 45
ANGLE OF INTERNAL FRICTION,
Fig. 12 Bearing Capacity Factor, N q for Driven Piles
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
41
ANNEX H
(Clauses 8.2.3.3 and 11. 2 A)
DETERMINATION OF DEPTH OF FIXITY, LATERAL DEFLECTION
AND MAXIMUM MOMENT OF LATERALLY LOADED PILES
HI DETERMINATION OF LATERAL
DEFLECTION AT THE PILE HEAD AND DEPTH
OF FIXITY
H-l.l The long flexible pile, fully or partially
embedded, is treated as a cantilever fixed at some depth
below the ground level (see Fig. 13).
H-1.2 Determine the depth of fixity and hence the
equivalent length of the cantilever using the plots given
in Fig. 13.
where
T=5E_^R = 4\EL
(K ] and K 2 are constants given in Tables 8 and 9, E
is the Young's modulus of the pile material in
kN/m 2 and / is the moment of inertia of the pile
cross-section in m 4 ).
NOTE — Figure 12 is valid for long flexible piles where the
embedded length L e is > AR or AT.
Table 8 Values of Constant K t (kN/m 3 )
(Clause H-1.2)
Type of Soil
(1)
Value
Dry
(2)
Submerged
(3)
Loose sand 2 600 1 460
Medium sand 7 750 5 250
Dense sand 20 750 12 450
Very loose sand under repeated — 400
loading or normally loading clays
Table 9 Values of Constant K x (kN/m 3 )
(Clause H-1.2)
Unconfined Compressive Strength
kN/m 2
(1)
Value
(2)
20 to 40
100 to 200
200 to 400
More than 400
7.75 x 10 4
48.80 x 10 4
97.75 x 10 4
195.50 x 10 4
2.3
2.1
o
\
\
§ 1.9
1.7
FREE HEAD PILE
FIXED HEAD PILE
\
\
\
h \
1.5 -
1.3
---._
-L
-L
4 6
L^/R OR L|/T
;<-e
■7777 77
^
-f
///'// /
}
FOR PILES IN SANDS
AND NORMALLY
LOADED CLAYS
}
FOR PILES IN
PRELOADED
CLAYS
10
Fig. 13 Determination of Depth Fixity
42
NATIONAL BUILDING CODE OF INDIA
H-1.3 Knowing the length of the equivalent cantilever
the pile head deflection (Y) shall be computed using
the following equations:
y(in m ) = Q^+M for free head pile
3 EI
G(A+A)
cantilever is higher than the actual maximum moment
(M) of the pile. The actual maximum moment is
obtained by multiplying the fixed end moment of the
equivalent cantilever by a reduction factor, m given in
Fig. 14. The fixed end moment of the equivalent
cantilever is given by:
12 EI
where Q is the lateral load in kN
for fixed head pile
H-2 DETERMINATION
MOMENT IN THE PILE
OF MAXIMUM
M f = Q {L x + L f )
G(A + A) 3
for free head pile
12 EI
for fixed head pile
H-2.1 The fixed end moment (M f ) of the equivalent
1.0
The actual maximum moment (A/) = m (M F ).
o
i-
o
<
LL
z
Q
O
D
Q
LU
0.8
0.6
0.4
0.2
T^ZT-
(/
4 6 8
LMR OR L1/T
10 12
* Q
FOR PILES IN
PRELOADED CLAYS
FOR PILES IN SANDS AND
NORMALLY LOADED CLAYS
14A FOR FREE HEAD PILE
" 77T, 77
Q
V
Li
>L
*//
'" J
i
g
LL
2
O
I-
o
3
Q
LU
q:
1.0
0.8
OR
^—- '
^^
-z^^*
0.5 1.0 1.5
L1/RORL1/7
FOR PILES IN
PRELOADED CLAYS
FOR PILES IN SANDS AND
NORMALLY LOADED CLAYS
2.0
2.5
I L 1
L
■
>-4
14B FOR FIXED HEAD PILE
Fig. 14 Determination of Reduction Factors for Computation
of Maximum Moment in Pile
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
43
ANNEX J
(Clause 11.2.2)
LOAD CARRYING CAPACITY OF UNDER-REAMED PILES
FROM SOIL PROPERTIES
J-l ULTIMATE LOAD CAPACITY
The ultimate load capacity of a pile can be calculated
from soil properties. The soil properties required are
strength parameters, cohesion, angle of internal friction
and soil density.
a) Clayey Soils — For clayey soils, the ultimate
load carrying capacity of an under-reamed
pile may be worked out from the following
expression:
Q =ANC+ANC' +C'A\ + aCA,
^u pep aca as as
where
Q a = Ultimate bearing capacity of pile in kN;
A = Cross-sectional area of the pile stem at the
toe level in m 2 ;
TV = Bearing capacity factor, usually taken as 9;
C = Cohesion of the soil around toe in kN/m 2;
p
A a = (7t/4) (£> u 2 - D 1 ), where D u and D are the
under-reamed and stem diameter, respectively
inm;
C a = Average cohesion of the soil along the pile
steminkN/m 2 ;
A = Surface area of the stem in m 2 ;
s '
A' s = Surface area of the cylinder circumscribing
the under-reamed bulbs in m 2 ;
C a - Average cohesion of the soil around the
under-reamed bulbs; and
a = Reduction factor (usually taken 0.5 for clays).
NOTES
1 The above expression holds for the usual spacing of under-
reamed bulbs spaced at not more than one and a half times
their diameter.
2 If the pile is with one bulb only, the third term will not
occur. For calculating uplift load, the first term will not occur
in the formula.
3 In case of expansive soil top 2 m strata should be neglected
for computing skin friction.
b) Sandy Soils
Q u = A p ( 1 /2D T yV T +Y^ f ^ q ) + A a ( 1 / 2 D u nYyV Y )
+ Y # q £ d r + l /2 % D y Ktan5 (rf, +dj +<)
where
A - n D 2 /4, where D is stem diameter in m;
A = n /4 (D\ - D 2 ) where D is the under-
reamed bulb diameter in m;
n = Number of under-reamed bulbs;
7 = Average unit weight of soil (submerged unit
weight in strata below water table) in
kN/m 3 ;
N y ,N q = Bearing capacity factors, depending upon
the angle of internal friction;
d T = Depth of the centre of different under-
reamed bulbs below ground level in m;
d f = Total depth of pile below ground level in m;
K - Earth pressure coefficient (usually taken as
1.75 for sandy soils);
5 - Angle of wall friction (may be taken as
equal to the angle of internal friction 0);
d x - Depth of the centre of the first under-
reamed bulb in m; and
d n - Depth of the centre of the last under-reamed
bulb in m.
NOTES
1 For uplift bearing on pile tip, A p will not occur.
2 N y will be as specified in good practice [6-2(7)]
and N q will be taken from Fig. 11.
c) Soil Strata having both Cohesion and Friction
— In soil strata having both cohesion and
friction or in layered strata having two types
of soil, the bearing capacity may be estimated
using both the formulae. However, in such
cases load test will be a better guide.
d) Compaction Piles in Sandy Strata — For
bored compaction piles in sandy strata, the
formula in (b) shall be applied but with the
modified value of (^ as given below:
l = (0+4O)/2
where
<j> = Angle of internal friction of virgin soil.
The values of A^, 7V q and 8 are taken
corresponding to <j) x The value of the earth
pressure coefficient K will be 3.
e) Piles Resting on Rock — For piles resting on
rock, the bearing component will be obtained
by multiplying the safe bearing capacity of
rock with bearing area of the pile stem plus
the bearing provided by the bulb portion.
NOTE — To obtain safe load in compression and uplift
from ultimate load capacity generally the factors of safety
will be 2.5 and 3 respectively.
44
NATIONAL BUILDING CODE OF INDIA
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and 'accepted standards'
in the fulfillment of the requirements of the Code. The
latest version of a standard shall be adopted at the time
of enforcement of the Code. The standards listed may
be used by the Authority as a guide in conformance
with the requirements of the referred clauses in the
Code.
IS No.
(1) 1892: 1979
2131 : 1981
2132: 1986
4434: 1978
4968
(Part 1) : 1976
(Part 2) : 1976
(Part 3): 1976
8763 : 1978
9214 : 1979
(2) 10042 : 1981
(3) 13365
(Part 1) : 1998
(4) 2720
(Part 1) : 1983
(Part 2): 1973
Title
Code of practice for subsurface
investigation for foundation
(first revision)
Method of standard penetration
test for soils (first revision)
Code of practice for thin walled
tube sampling of soils (second
revision)
Code of practice for in-situ
vane shear test for soils (first
revision)
Method for sub-surface
sounding for soils:
Dynamic method using 50 mm
cone without bentonite slurry
(first revision)
Dynamic method using cone
and bentonite slurry (first
revision)
Static cone penetration test
(first revision)
Guide for undisturbed
sampling of sands and sandy
soils
Method for determination of
modulus of subgrade reaction
(lvalue) of soils in the field
Code of practice for site-
investigations for foundation in
gravel boulder deposits
Guidelines for quantitative
classification systems of rock
mass: Part 1 RMR for predicting
of engineering properties
Methods of tests for soils:
Preparation of dry soil samples
for various tests (second
revision)
Determination of water content
(second revision)
IS No.
(Part 3/Sec 1) :
1980
(Part 3/Sec 2) :
1980
(Part 4) : 1985
(Part 5) : 1985
(Part 10) : 1991
(Part 13) : 1986
(Part 15) : 1986
(Part 28): 1974
(Part 29): 1975
(Part 33): 1971
(Part 34) : 1972
(Part39/Sec 1) :
1977
(5) 1498 : 1970
(6) 401 : 2001
(7) 6403 : 1981
(8) 1888 : 1982
(9) 2131 : 1981
Title
Determination of specific
gravity, Section 1 Fine grained
soils (first revision)
Determination of specific
gravity, Section 2 Fine, medium
and coarse grained soils (first
revision)
Grain size analysis (second
revision)
Determination of liquid and
plastic limits (second
revision)
Determination of unconfined
compressive strength (second
revision)
Direct shear test (second
revision)
Determination of consolidation
properties (first revision)
Determination of dry density of
soils in place, by the sand
replacement method (first
revision)
Determination of dry density of
soils in place, by the core cutter
method (first revision)
Determination of the density
in-place by the ring and water
replacement method
Determination of density of
soils in-place by rubber-
balloon method
Direct shear test for soils
containing gravel, Section 1
Laboratory test
Classification and identification
of soils for general engineering
purposes (first revision)
Code of practice for preservation
of timber (fourth revision)
Code of practice for
determination of bearing
capacity of shallow foundations
(first revision)
Method of load tests on soils
(second revision)
Method for standard
penetration test for soils (first
revision)
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
45
IS No.
Title
IS No.
Title
(10) 8009
(Part 1) : 1976
(11) 1904: 1986
(12)3764: 1992
(13)456:2000
(14) 1905 : 1987
(15) 1080: 1985
(16) 11089: 1984
(17)2911
(Part 1/Sec 1):
1979
(Part 1/Sec 2) :
1979
(18) (Part 4): 1985
(19) 14893:2001
(20)2911
(Part 1/Sec 3) :
1979
(21) (Part 1/Sec 4):
1979
(22) (Part 3): 1980
(23) (Part 2) : 1980
(24) 2974
Code of practice for calculation
of settlement of foundations:
Part 1 Shallow foundations
subjected to symmetrical static
vertical loads
Code of practice for design and
construction of foundations in
soils: General requirements
(third revision)
Code of safety for excavation
work (first revision)
Code of practice for plain and
reinforced concrete (fourth
revision)
Code of practice for structural
use of unreinforced masonry
(third revision)
Code of practice for design
and construction of shallow
foundations in soils (other than
raft, ring and shell) (second
revision)
Code of practice for design
and construction of ring
foundations
Code of practice for design
and construction of pile
foundations:
Concrete piles, Section 1 Driven
cast in-situ concrete piles (first
revision)
Concrete piles, Section 2 Bored
cast in-situ piles (first revision)
Load test on piles (first revision)
Guidelines for non-destructive
integrity testing of piles
Code of practice for design
and construction of pile
foundations:
Concrete piles, Section 3
Driven precast concrete piles
(first revision)
Concrete piles, Section 4 Bored
precast concrete piles
Under-reamed pile foundation
(first revision)
Timber piles (first revision)
Code of practice for design
and construction of machine
foundation
(Part 1) : 1982
(Part 2) : 1980
(Part 3) : 1992
(Part 4): 1979
(Part 5): 1987
13301 : 1992
9556 : 1980
(25) 13094: 1992
(26) 13162
(Part 2): 1991
13321
(Part 1) : 1992
13325 : 1992
13326
(Parti): 1992
14293 : 1995
14294 : 1995
14324 : 1995
Foundations for reciprocating
type machine (second revision)
Foundations for impact type
machines (hammer foundations)
(first revision)
Foundations for rotary type
machines (medium and high
frequency) (second revision)
Foundations for rotary type
machines of low frequency
(first revision)
Foundations for impact
machines other than hammers
(forging and stamping press;
pig breakers, drop crusher and
jetter) (first revision)
Guidelines for vibration
isolation for machine
foundations
Code of practice for design and
construction of diaphragm walls
Guidelines for selection of
ground improvement techniques
for foundation in weak soils
Geotextiles — Methods of test:
Part 2 Determination of
resistance to exposure of ultra-
violet light and water (Xenon
arc type apparatus)
Glossary of terms for geo-
synthetics: Part 1 Terms used
in materials and properties
Method of test for the
determination of tensile
properties of extruded polymer
geogrids using the wide strip
Method of test for the
evaluation of interface friction
between geosynthetics and soil:
Part 1 Modified direct shear
technique
Geotextiles — Method of test
for trapezoid tearing strength
Geotextiles — Method for
determination of apparent
opening size by dry sieving
technique
Geotextiles — Methods of test
for determination of water
permeability-permittivity
46
NATIONAL BUILDING CODE OF INDIA
IS No. Title
14706 : 1999 Geotextiles — Sampling and
preparation of test specimens
14714 : 1999 Geotextiles — Determination
of abrasion resistance
14715 : 2000 Woven jute geotextiles —
Specification
14716 : 1999 Geotextiles — Determination
of mass per unit area
14739 : 1999 Geotextiles — Methods for
determination of creep
IS No.
14986 : 2001
15060 : 2001
(27) 9214 : 1979
Title
Guidelines for application of jute
geo-grid for rain water erosion
control in road and railway
embankments and hill slopes
Geotextiles — Tensile test for
joints/seams by wide width
method
Method of determination of
subgrade reaction (lvalue) of
soils in the field
PART 6 STRUCTURAL DESIGN — SECTION 2 SOILS AND FOUNDATIONS
47
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 3 Timber and Bamboo: 3A Timber
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 SYMBOLS
4 MATERIALS
5 PERMISSIBLE STRESSES
6 DESIGN CONSIDERATIONS
7 DESIGN OF COMMON STEEL WIRE NAIL JOINTS
8 DESIGN OF NAIL LAMINATED TIMBER BEAMS
9 DESIGN OF BOLTED CONSTRUCTION JOINTS
1 DESIGN OF TIMBER CONNECTOR JOINTS
1 1 GLUED LAMINATED CONSTRUCTION AND FINGER JOINTS
1 2 LAMINATED VENEER LUMBER
1 3 DESIGN OF GLUED LAMINATED BEAMS
1 4 STRUCTURAL USE OF PLYWOOD
15 TRUSSED RAFTER
16 STRUCTURAL SANDWICHES
17 LAMELLA ROOFING
1 8 NAIL AND SCREW HOLDING POWER OF TIMBER
1 9 PROTECTION AGAINST TERMITE ATTACK IN BUILDINGS
LIST OF STANDARDS
5
5
6
7
21
22
26
32
34
37
40
41
42
43
43
45
46
48
48
49
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
This Section deals with the structural design aspect of timber structures. In this section, the various Species of
Indian timber, classified into three groups depending on the structural properties influencing the design, most are
included.
In the previous version of the Code, timber was covered under Section 3 of Part 6 under the title 'Wood' , which
did not cover bamboo. Now this Section 3 has been enlarged as Section 3 Timber and Bamboo, which has been
sub-divided into sub-section 3A Timber and sub-section 3B Bamboo. This sub-section pertains to 3A Timber.
This Section was first published in 1970 which was subsequently revised in 1983. In the first revision provisions
of this Section were updated and design of nailed laminated timber beams were included and information on
bolted construction joints was added. As a result of experience gained in implementation of 1983 version of this
Code and feedback received as well as formulation of new standards in the field and revision of some of the
existing standards, a need to revise this Section was felt. This revision has, therefore, been brought out to take
care of these aspects. The significant changes incorporated in this revision include the following:
a) A number of terminologies related to timber for structural purpose have been added.
b) Strength data of additional species of timber have been included.
c) Requirements for structural timber and preferred cut sizes thereof have been modified.
d) Requirements for glued laminated construction and finger joints have been introduced.
e) Requirements for laminated veneer lumber have been introduced.
f) Brief details have been included for structural sandwiches, glued laminated beams, lamella roofing, nail
and screw holding power of timber, structural use of plywood and trussed rafter; these are proposed to
be further elaborated in future revisions of this Section.
g) Guidelines for protection against termite attack in buildings have been added,
h) Reference to all the concerned Indian Standards have been updated.
In the present day context of dwindling forest resources, all efforts are being made to effect judicious use of timber.
In this context, the Indian Standards now permit use of plantation timbers including certain fast growing species and
suitable guidelines in terms of their seasoning, sawing, treatment, etc have been made available. In the same way,
use of finger jointing and glued laminated timber is important and standardization on the same is desirable and is
under due consideration. However, in the absence of detailed Indian Standard Specifications and Codes of practice
in these areas at present, general details on the same have been incorporated in the revision of this part.
The information contained in this Section is largely based on the following Indian Standards:
IS No. Title
399 : 1963 Classification of commercial timbers and their zonal distribution (revised)
883 : 1994 Code of practice for design of structural timber in building (fourth revision)
1 150 : 2000 Trade names and abbreviated symbols for timber species (third revision)
2366 : 1983 Code of practice for nail-jointed timber construction (first revision)
4891 : 1988 Specification for preferred cut sizes of structural timber (first revision)
4983 : 1968 Code of practice for design and construction of nailed laminated timber beams
1 1096 : 1984 Code of practice for design and construction of bolt-jointed timber construction
14616 : 1999 Specification for laminated veneer lumber
All standards, whether given herein above or cross-referred to in the main text of this Section, are subject to
revision. The parties to agreement based on this Section are encouraged to investigate the possibility of applying
the most recent editions of the standards.
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER 3
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 3 Timber and Bamboo: 3A Timber
1 SCOPE
1.1 This Section relates to the use of structural timber
in structures or elements of structures connected
together by fasteners/fastening techniques.
1.2 This shall not be interpreted to prevent the use of
material or methods of design or construction not
specifically mentioned herein; and the methods of
design may be based on analytical and engineering
principles, or reliable test data, or both, that
demonstrate the safety and serviceability of the
resulting structure. Nor is the classification of timber
into strength groups to be interpreted as preventing
the use of design data desired for a particular timber
or grade of timber on the basis of reliable tests.
2 TERMINOLOGY
2.0 For the purpose of this Section, the following
definitions and those in accordance with accepted
standard [6-3A(l)], shall apply.
2.1 Structural Purpose Definitions
2.1.1 Beam, Built-Up-Laminated — A beam made by
joining layers of timber together with mechanical
fastenings, so that the grain of all layers is essentially
parallel.
2.1.2 Beam, Glued-Laminated — A beam made by
bonding layers of veneers or timber with an adhesive,
so that grain of all laminations is essentially parallel.
2.1.3 Diaphragm, Structural — A structural element
of large extent placed in a building as a wall, or roof,
and made use of to resist horizontal forces such as wind
or earthquakes-acting parallel to its own plane.
2.1.4 Duration of Load — Period during which a
member or a complete structure is stressed as a
consequence of the loads applied.
2.1.5 Edge Distance — The distance measured
perpendicular to grain from the centre of the connector
to the edge of the member.
2.1.6 End Distance — The distance measured parallel
to grain of the member from the centre of the connector
to the closest end of timber.
2.1.7 Finger Joint — Joint produced by connecting
timber members end-to-end by cutting profiles (tapered
projections) in the form of V-shaped grooves to the
ends of timber planks or scantlings to be joined, glueing
the interfaces and then mating the two ends together
under pressure.
2.1.8 Fundamental or Ultimate Stress — The stress
which is determined on small clear specimen of timber,
in accordance with good practice [6-3 A(2)]; and does
not take into account the effect of naturally occurring
characteristics and other factors.
2.1.9 Inside Location — Position in buildings in which
timber remains continuously dry or protected from
weather.
2.1.10 Laminated Veneer Lumber — A structural
composite made by laminating veneers, 1.5 mm to
4.2 mm thick, with suitable adhesive and with the grain
of veneers in successive layers aligned along the
longitudinal (length) dimension of the composite.
2.1.11 Loaded Edge Distance — The distance
measured from the centre to the edge towards which
the load induced by the connector acts, and the
unloaded edge distance is the one opposite to the loaded
edge.
2.1.12 Location — A term generally referred to as
exact place where a timber is used in building.
2.1.13 Outside Location — Position in buildings in
which timbers are occasionally subjected to wetting
and drying as in the case of open sheds and outdoor
exposed structures.
2.1.14 Permissible Stress — Stress obtained by
applying factor of safety to the ultimate stress.
2.1.15 Sandwich, Structural — A layered construction
comprising a combination or relatively high-strength
facing material intimately bonded to and acting
integrally with a low density core material.
2.1.16 Spaced Column — Two column sections
adequately connected together by glue, bolts, screws
or otherwise.
2.1.17 Structure, Permanent — Structural units in
timber which are constructed for a long duration and
wherein adequate protection and design measures have
initially been incorporated to render the structure
serviceable for the required life.
2.1.18 Structure, Temporary — Structures which are
erected for a short period, such as hutments at project
sites, for rehabilitation, temporary defence
constructions, exhibition structures, etc.
2.1.19 Structural Element — The component timber
members and joints which make up a resulting
structural assembly.
2.1.20 Structural Grades — Grades defining the
maximum size of strength reducing natural
characteristics (knots, sloping grain, etc) deemed
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
permissible in any piece of structural timber within
designated structural grade classification.
2.1.21 Structural Timber — Timber in which strength
is related to the anticipated in-service use as a controlling
factor in grading and selection and/or stiffness.
2.1.22 Termite — An insect of the order Isoptera
which may burrow in the wood or wood products of a
building for food or shelter.
2. 1 .23 Wet Location — Position in buildings in which
timbers are almost continuously damp or wet in contact
with the earth or water, such as piles and timber
foundations.
2.2 Definitions of Defects in Timber
2.2.1 Check — A separation of fibres extending along
the grain which is confined to one face of a piece of
wood.
2.2.2 Compression Wood — Abnormal wood which
is formed on the lower sides of branches and inclined
stems of coniferous trees. It is darker and harder than
normal wood but relatively low in strength for its
weight. It can be usually identified by wide eccentric
growth rings with abnormally high proportion of
growth latewood.
2.2.3 Dead Knot — A knot in which the layers of
annual growth are not completely intergrown with
those of the adjacent wood. It is surrounded by pitch
or bark. The encasement may be partial or complete.
2.2.4 Decay or Rot — Disintegration of wood tissue
caused by fungi (wood destroying) or other micro-
organisms.
2.2.5 Decayed Knot — A knot softer than the
surrounding wood and containing decay.
2.2.6 Diameter of Knot — The maximum distance
between the two points farthest apart on the periphery
of a round knot, on the face on which it becomes
visible. In the case of a spike or a splay knot, the
maximum width of the knot visible on the face on
which it appears shall be taken as its diameter.
2.2.7 Discolouration — A change from the normal
colour of the wood which does not impair the strength
of the wood.
2.2.8 Knot — A branch base or limb embedded in the
tree or timber by natural growth.
2.2.9 Knot Hole — A hole left as a result of the
removal of a knot.
2.2.10 Live Knot — A knot free from decay and other
defects, in which the fibres are firmly intergrown with
those of the surrounding wood. Syn. Tntegrown knot';
cf. 'Dead Knot'.
2.2. 1 1 Loose Grain (Loosened Grain) — A defect on a
flat sawn surface caused by the separation or raising of
wood fibres along the growth rings; cf, 'Raised Grain'.
2.2.12 Loose Knot — A knot that is not held firmly in
place by growth or position, and that cannot be relied
upon to remain in place; cf Tight Knot'.
2.2.13 Mould — A soft vegetative growth that forms
on wood in damp, stagnant atmosphere. It is the least
harmful type of fungus, usually confined to the surface
of the wood.
2.2.14 Pitch Pocket — Accumulation of resin between
growth rings of coniferous wood as seen on the cross
section.
2.2.15 Sap Stain — Discolouration of the sapwood
mainly due to fungi.
2.2.16 Sapwood — The outer layer of log, which in
the growing tree contain living cells and food material.
The sapwood is usually lighter in colour and is readily
attacked by insects and fungi.
2.2.17 Shake — A partial or complete separation
between adjoining layers of tissues as seen in end
surfaces.
2.2.18 Slope of Grain — The inclination of the fibres
to the longitudinal axis of the member.
2.2.19 Sound Knot — A tight knot free from decay,
which is solid across its face, and at least as hard as
the surrounding wood.
2.2.20 Split — A crack extending from one face of a
piece of wood to another and runs along the grain of
the piece.
2.2.21 Tight Knot — A knot so held by growth or
position as to remain firm in position in the piece of
wood; cf 'Loose Knot',
2.2.22 Wane — The original rounded surface of a tree
remaining on a piece of converted timber.
2.2.23 Warp — A deviation in sawn timber from a
true plane surface or distortion due to stresses causing
departure from a true plane.
2.2.24 Worm Holes — Cavities caused by worms.
3 SYMBOLS
3.1 For the purpose of this Section, the following letter
symbols shall have the meaning indicated against each:
a - Projected area of bolt in main member
(t' x d 3 ), mm 2
B = Width of the beam, mm
C = Concentrated load, N
D = Depth of beam, mm
D x = Depth of beam at the notch, mm
D 2 = Depth of notch, mm
d = Dimension of least side of column, mm
NATIONAL BUILDING CODE OF INDIA
4 =
4 =
d. =
E =
F =
•'ab —
/ =
J at
f, =
/. =
/ =
** CD
/ =
r =
x =
H =
/ =
JT =
*. =
X, =
Least overall width of box column, mm
Least overall dimension of core in box
column, mm
Diameter of bolt, mm
Bolt-diameter factor
Length of the notch measured along the
beam span from the inner edge of the support
to the farthest edge of the notch, mm
Modulus of elasticity in bending, N/mm 2
Load acting on a bolt at an angle to grain, N
Calculated bending stress in extreme fibre,
N/mm 2
Calculated average axial compressive
stress, N/mm 2
Calculated axial tensile stress, N/mm 2
Permissible bending stress on the extreme
fibre, N/mm 2
Permissible stress in axial compression,
N/mm 2
Permissible stress in compression normal
(perpendicular) to grain, N/mm 2
Permissible stress in compression parallel
to grain, N/mm 2
Permissible compressive stress in the
direction of the line of action of the load,
N/mm 2
Permissible stress in tension parallel to
grain, N/mm 2
Horizontal shear stress, N/mm 2
Moment of inertia of a section, mm 4
Coefficient in deflection depending upon
type and criticality of loading on beam
Modification factor for change in slope of
grain
Modification factor for change in duration
of loadings
*5,
and
y = Form factors
K n =
K
Modification factor for bearing stress
Constant equal to 0.584 J r
U E
K 9 = Constant equal to 2\l5a f
2.5E
K ]0 = Constant equal to 0.584 J r
L = Span of a beam or truss, mm
M = Maximum bending moment in beam,
N/mm 2
AT = Total number of bolts in the joint
n = Shank diameter of the nail, mm
P = Load on bolt parallel to grain, N
p Y - Ratio of the thickness of the compression
flange to the depth of the beam
Q = Statical moment of area above or below the
neutral axis about neutral axis, mm 3
q = Constant for particular thickness of plank
q x - Ratio of the total thickness of web or webs
to the overall width of the beam
R = Load on bolt perpendicular (normal) to
grain, N
S = Unsupported overall length of column, mm
t = Nominal thickness of planks used in
forming box type column, mm
t' = Thickness of main member, mm
U = Constant for a particular thickness of the
plank
V - Vertical end reaction or shear at a section, N
* W - Total uniform load, N
x = Distance from reaction to load, mm
Y = A factor determining the value of form
factor K A
8 ~ Deflection at middle of beam, mm
= Angle of load to grain direction
Z = Section modulus of beam, mm 3
A { = Percentage factor for fid ratio, parallel to
grain
A 2 = Percentage factor for fid ratio, perpendicular
to grain
4 MATERIALS
4.1 Species of Timber
The species of timber recommended for structural
purposes are given in Table 1 .
4.1.1 Grouping
Species of timber recommended for constructional
purposes are classified in three groups on the basis of
their strength properties, namely, modulus of elasticity
(E) and extreme fibre stress in bending and tension
The characteristics of these groups are as given below:
Group A — E above 12.6 x 10 3 N/mm 2 and f b
above 18.0 N/mm 2 .
Group B — E above 9.8 x 10 3 N/mm 2 and up
to 12.6 x 10 3 N/mm 2 and/ b above
12.0 N/mm 2 and up to 1 8.0 N/mm 2 .
PART 6 STRUCTURAL DESIGN — SECTIONS TIMBER AND BAMBOO: 3A TIMBER
Group C — E above 5.6 x 10 3 N/mm 2 and up
to 9.8 x 10 3 N/mm 2 and f b above
8.5 N/mm 2 and up to 12.0 N/mm 2 .
NOTE — Modulus of elasticity given above is applicable
for all locations and extreme fibre stress in bending is for
inside location.
4.1.2 Timber species may be identified in accordance
with good practice [6-3 A(3)].
4.2 The general characteristics like durability and
treatability of the species are also given in Table 1 .
Species of timber other than those recommended in
Table 1 may be used, provided the basic strength
properties are determined and found in accordance
with 4.1.1.
NOTE — For obtaining basic stress figures of the unlisted
species, reference may be made to the Forest Research Institute,
Dehra Dun.
4.3 The permissible lateral strength (in double shear)
of mild steel wire shall be as given in Table 2 and
Table 3 for different species of timber.
4.4 Moisture Content in Timber
The permissible moisture content of timber for various
positions in buildings shall be as given in Table 4.
4.5 Sawn Timber
4.5.1 Sizes
Preferred cut sizes of timber for use in structural
components shall be as given in Tables 5 to 7.
4.5.2 Tolerances
Permissible tolerances in measurements of cut sizes
of structural timber shall be as follows:
a) For width and thickness:
+3.
1) Up to and including 100 mm _^mm
+6
-3
*-■?■
mm
2) Above 100 mm
b) For length
4.6 Grading of Structural Timber
4.6.1 Cut sizes of structural timber shall be graded,
after seasoning, into three grades based on permissible
defects given in Table 8:
a) Select Grade
b) Grade I
c) Grade II
4.6.2 The prohibited defects given in 4.6.2.1 and
permissible defects given in 4.6.2.2 shall apply to
structural timber.
4.6.2.1 Prohibited defects
Loose grains, splits, compression wood in coniferous
species, heartwood rot, sap rot, crookedness, worm
holes made by powder post beetles and pitch pockets
shall not be permitted in all the three grades.
4.6.2.2 Permissible defects
Defects to the extent specified in Table 8 shall be
permissible.
NOTE — Wanes are permitted provided they are not combined
with knots and the reduction in strength on account of the wanes
is not more than the reduction with maximum allowable knots.
4.6.3 Location of Defects
The influence of defects in timber is different for
different locations in the structural element. Therefore,
these should be placed during construction in such a
way so that they do not have any adverse effect on the
members, in accordance with good practice [6-3 A(5)].
4.7 Suitability
4.7.1 Suitability in Respect of Durability and
Treatability for Permanent Structures
There are two choices as given in 4.7.1.1 and 4.7.1.2.
4.7.1.1 First choice
The species shall be any one of the following:
a) Untreated heartwood of high durability.
Heartwood if containing more than 15 percent
sap wood, may need chemical treatment for
protection;
b) Treated heartwood of moderate and low
durability and class 'a' and class 'b'
treatability;
c) Heartwood of moderate durability and class
'c' treatability after pressure impregnation; and
d) Sapwood of all classes of durability after
thorough treatment with preservative.
4.7.1.2 Second choice
The species of timber shall be heartwood of moderate
durability and class 'd' treatability.
4.7.2 Choice of load-bearing temporary structures or
semi-structural components at construction site
a) Heartwood of low durability and class V
treatability; or
b) The species whose durability and/or treatability
is yet to be established, as listed in Table 1.
4.8 Fastenings
All structural members shall be framed, anchored, tied
and braced to develop the strength and rigidity
necessary for the purposes for which they are used.
8
NATIONAL BUILDING CODE OF INDIA
Table 1 Safe Permissible Stresses for the Species of Timber
[Clauses 4.1, 4.2, 4.7.2 (b), 5.4.1, 5,4.2 and 6.5.8.3.1 (b)]
Species
Botanical Name
Trade Name
Locality
from
Where
Tested
Average Modulus of
Density at Elasticity
12 percent
Moisture
Content
kg/m 3
Permissible Stress in N/mm 2 for Grade I
Preservative Characters
*
-^
Lll Grades
Bending i
and
Shear
Compression
Compression
and All
Tension Along
all Locations
Parallel
Perpendicular
vocations
Grain, Extreme
to Grain
to Grain
xlO 3
Fibre Stress
N/mm 2
>^
^*w
r~
^
/■"
"N
r
C
c
e
o
a
o
a
2
O
C
o
cd
ca
o
'S a
.3
o
•■a
3
1
O
8
o
ide Loc
Locatio
12
3
o
13
o
C
o
<
3
o
"5
32
Outs
Wet
tDurability t Treat- §Refrac-
Class ability teriness
Grade to All
Seasoning
(1)
(2)
(3)
(4)
(5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17)
(18) (19)
GROUP A
Acacia catecthu
Acacia chundra
Albizia odoratissima
Bruguiera spp.
Grewia tiliifolia
Hopea utilis
(Balano carpus utilis)
Hopea glabra
Hopea parviflora
Manilota polyandra (Syn.
Cynometra polyandra)
Mesuaferrea
Mimusops littoralis
Pesciloneuron indicum
Pterocarpus Scamalinus
Sageraea elliptiea
Stereospermun celonoides
Vitex alUssima
GROUP B
Albizzia lebbeck
Khair (KHA)
Red kutch
Kala sins (KS1)
Bruguiera (BSV)
(Mangrove)
Dhaman (DHA)
Karung
Hopea (HOP)
Hopea (HOP)
Ping (PIG)
Mesua (MES)
Bullet-wooi^BUL)
Ballagi (BAL)
Red sanders (MA)
Chooi (COC)
Padri(PAD)
Mflla (MIL)
Kokko(KOK)
U.P.
MP.
Chennai
Andmans
Chennai
Chennai
Chennai
Chennai
Assam
Assam
S. Andaman
Chennai
Chennai
Andmans
Chennai
Maharashtra
Andaman
1 009
1086
737
897
788
987
1081
923
903
965
1 103
1139
1 121
869
731
937
642
13.44 20.1 16.8 13.4
16.79 26,5 22.0 17.6
13.54 18.7 15.6 12.5
17.68 21.9 18.3 14.6
14.82 18.3 15.2 12.2
16.91 25.1 20.9 16.7
14.79 21.3 17.8 14.2
13.03 18.6 15.5 12.4
13.20 19.1 15.9 12.7
16.30
17.39
16.29
12.73
15.06
12.94
13.01
23.3
22.7
22.4
19.4
18.9
18.7
25.0 20.9
21.5 17.9
19.0
18.2
15.8
15.2
15.5
15.1.
15.0
16.7
143
12.7
12.1
1.6
2.2
1.5
1.2
1.3
1.5
1.5
1.3
1.3
1.2
1.5
1.5
1.7
1.1
1.1
1.2
2.2
3.2
2.2
1.7
13.8
17.9
13.3
14.3
12.3
15.9
11.8
12.7
10.1
13.0
9.6
10.4
1.9 12.0
2.2 16.4
10.7 8.7
14.6 11.9
2.2
1.8
1.8
1.8
2.1
2.2
2.5
1.5
1.6
1.7
14.5
13.2
.1.2
15.5
14.2
14.7
18.1
12.5
11.9
12.6
12.9
11.8
10.4
13.8
12.7
13.1
16.1
11.1
10.6
11.2
10.6
9.6
8.5
11.3
10.4
10.7
13.2
9.1
8.7
9.2
7.7
10.9
7.3
5.5
6.0
9.3
9.9
9.2
5.7
5.9
11.3
8.7
11.8
5.3
4.0
9.5
6.0
8.4
5.6
4.3
4.7
7.3
7.7-
7.3
4.4
4.6
8.8
6.8
9.2
4.1
3.1
7.4
4,9
6.9
4.6
3.5
I
III
3.8 III
5.9 —
6.3
6.0
3.6
3.7
7.2
5.5
7.5
3.4
2.6
6.1
I
I
ID
I
I
III
I
A
A
B
A
A
A
A
A
A
A
A
B
A
11.17 13.4 11.2 9.0 1.1 1.5 9.0 8.0 6.5 4.4 3.4 2.8
Table 1 — Continued
(1)
(2)
(3)
(4)
(5)
(6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17)
(18) (19)
I
I
1
i
Anogeissus latifolia
Artocarpus hirsulus
Acacia nilotica
Acacia ferruginea
Acrocarpus fraxinifolius
Aglaia odutis
Anogeissus acuminota
Atalanlia monophylla
Altingia excelsa
Amoora spp.
Buckiandia populnea (Syn
Exbucklandia populnea)
Cassia fistula
Carallia lucida
Canarium strictum
Cassia sienea
Casuerina equisetifolia
Celophyllum temculosum
Chloroxylon swielenia
Cullenia resayoana
(Syn C. execelsa)
Diploknema butyracea
(Syn Bassia butyrance)
Dyscxylum malebaricum
Dipterocarpus grandiflorus
Dipterocarpus macrocarpus
Dichopsis polyantha (Syn
Palaquium polyanthum)
Dichopsis elliptica
(Syn Palaquium ellipticum)
Diospyros micropylla
Diospyros pyrrhocaipus
Dipterocarpus bourdilloni
Eucalyptus globulus
Eucalyptus ougenioides
Dhaura, Axle wood
(AXL) (Bakli)
Aini(AIH)
Babul (BAB)
Safed khair
Mundani (MUN)
Aglaia (AGL)
Yon
Jungli-nimbu (JHI)
Jutili (JUT)
Amari (AMA)
Pipli (PIP)
Amaltas (AMT)
Maniawaga
Dhup
Kasod
Casuarina (CAS)
Poon (POO)
Satin wood (CFI)
Karani(KAP)
Hillmahua(HMA)
White ceda (WCE)
Gurjan (GUR)
Hollong (HQL)
Tali(TAL)
Pali (PAL)
U.P.
Chennai
U.P.
Maharashtra
Chennai
Assam
Orissa
Orissa
Assam
W. Bengal
W. Bengal
U.P.
Assam
Chennai
M.P.
Orissa
Maharashtra
M.P.
Chennai
S. Andaman
Chennai
N. Andaman
Assam
Assam
Chennai
892
600
797
993
690
815
844
897
795
625
672
865
748
655
820
769
657
865
625
780
745
758
726
734
606
10.55 16.1 13.4 10.7 1.1 1.6 9.1 8.1 6.6 4.7 3.7 3.0
10.45 15.0 12.5 10.0 0.7. 1.1 10.4 9.2 7.5 3.3 2.6 2.1
12.28
12.59
12.56
11.67
10.31
11.37
1.05
9.89
11.86
10.50
11.44
9.77
11.69
12.43
23.0
16.1
18.2
17.6
16.7
17.1
13.4
12.8
12.9
19.2
13.4
15.2
14.7
13.9
14.3
1.1
10.7
10.3
15.3
10.8
12.1
11.7
11.1
11.4
9.2
8.6
1.4
1.7
1.2
1.4
1.3
1.5
1.2
0.9
1.1
2.1
2.4
1.8
2.0
1.8
2.1
1.8
1.3
1.5
8.9
13.9
10.5
10.1
10.8
11.3
11.0
8.4
7.9
7.9
12.4
9.4
8.9
9.6
10.0
9.8
7.4
7.0
6.4
10.1
7.7
7.3
7.9
8.2
8.0
6.0
5.7
5.2
9.9
4.6
4.4
5.1
6.3
6.8
3.7
3.5
13.3
15.4
14.6
13.4
18.2
14.7
11.1
12.8
12.2
11.2
15.1
12.3
8.9
10.9
9.8
9.0
12.1
9.8
0.9
1.0
1.3
0.8
1.4
0.6
1.2
1.4
1.8
1.1
2.0
0.9
8.1
10.8
8.2
8.6
10.9
9.0
7.2
9.6
7.3
7.7
9.7
8.0
5.9
7.9
5.9
6.3
8.0
6.6
2.8
5.5
4.0
2.8
6.3
2.7
10.92 13.2 11.0
11.71 12.5 10.5
13.34 14.5 12.0
11.24 14.9 12.4
8.8
8.4
9.6
10.0
1.0
0.8
0.8
1.1
1.4
.1.1
1.1
1.6
8.0
7.9
8.8
9.9
7.1
7.1
7.9
8.8
5.8
5.8
6.4
7.2
3.1
2.7
3.5
4.7
4,0
7.7
3.6
3.4
4.0
4.9
5.3
2.9
2.7
2.2
4.3
3.1
2.2
4.9
2.1
2.4
2.1
2.7
3.7
3.3
6.3
2.9
2.8
3.3
4.0
4.4
2.4
2.2
11.80 19.2 16.0 12.8 1.4 2.0 12.3 10.9 8.9 7.2 5.6 4.6
12.60 18.4 15.3 12.3 1.2 1.7 11.4 10.1 8.3 5.9 4.6 3.8
1.8
3.5
2.5
1.8
4.0
1.7
10.64 15.3 12.8 10.2 1.0 1.5 9.9 8.8 7.2 6.6 5.2 4.2
1.9
1.7
2.2
3.0
11.86 13.9 11.6 9.3 0.7 1.0 8.5 7.5 6.2 2.9 2.2 1.8
I
I
I
in
n
n
ra
i
ni
m
n
m
m
i
i
m
B
B
B
A
A
A
B
C
A
B
A
C
B
B
B
B
Ebony (EBO)
Maharashtra
776
12.15
14.2
11.9
9.5
0.9
1.3
8.3
7.3
6.0
3.3
2.6
2.1
__
—
A
Ebony (EBO)
N. Andaman
843
9.93
13.5
11.2
9.0
1.0
1.4
,7.9
7.0
5.7
4.0
3.1
2.5
m
—
A
Gurjan (GUR)
Kerala
699
12.71
13.6
11.3
9.0
0.7
1.0
7.8
6.9
5.7
2.5
1.9
1.6
—
—
B
Eucalyptus
Chennai
912
14.83
15.9
13.2
10.6
10.3
1.5
9.0
8.0
6.5
3.4
2.6
2.1
i
e
A
(Blue gum) (BLN)
Eucalyptus
Chennai
853
11.47
16.4
13.6
10.9
1,2
1.7
11.3
10.0
8.2
7.6
5.9
4.8
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PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
11
2
H
I
►
w
o
o
n
o
o
w
o
Table 1
— Continued
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
(16)
(17)
(18)
(19)
Terminalia citrina
Assam
755
11.89
17.1
14.3
11.4
1.1
1.6
10.8
9.6
7.9
5.0
3.9
3.2
—
—
—
Terminalia manii
Black-chuglam (BCH)
S. Andaman
822
12.66
16.8
14.0
11.2
1.1
1.6
10.3
9.2
7.5
5.1
4.0
3.2
n
a
B
Tectona grandis
Teak (TEA)
U.P
660
9.97
15.5
12.9
10.3
1.2
1.6
9.4
8.3
6.8
4.5
3.5
2.8
i
e
B
Terminalia paniculate
Kindal (KIN)
Maharashtra
765
10.57
13.1
10.9
8.7
0.9
1.3
8.6
7.7
6.3
3.6
2.8
2.3
i
c
A
Alreminalia alata
Laurel (LAU), Sain
Chennai
906
10.54
15.1
12.5
10.0
1.1
1.6
9.4
8.4
6.8
6.2
4.8
4.0
i
b
A
Terminalia bilata
White-chuglam (WCH)
S. Andaman
690
12.38
15.5
13.0
10.4
0.9
1.2
9.8
8.7
7.1
3.6
2.8
2.3
ni
e
B
Thespesia populnea
Bhendi (BHE)
Maharashtra
766
10.36
18.9
15.8
12.6
1.3
1.9
11.3
10.0
8.2
4.4
3.4
2.8
—
—
B
Xylia xylocarpa
Irul(IRU)
Maharashtra
839
11.63
16.2
13.5
10.8
1.3
1.8
10.9
9.7
7.9
7.8
6.0
4.9
i
e
A
Zanthoxylum budranga
Mullilam (MUL)
W. Bengal
587
10.65
14.7
12.2
9.8
0.9
1.2
9.5
8.4
6.9
3.4
2.6
2.1
i
e
B
Adina oligocephala
—
Arunachal
715
11.17
15.2
12.7
10.1
1.2
1.7
10.3
9.2
7.5
4.0
3.1
2.4
—
—
—
Castanopsis indica
Chestnut
Meghalaya
688
12.54
14.8
12.3
9.9
1.0
1.4
9.8
8.7
7.1
3.4
2.7
2.2
—
—
B
Eucalyptus citriodara
Eucalyptus
Nilgiri
831
12.12
17.3
14.4
11.5
1.4
2.0
11.0
9.8
8.0
4.2
3.3
2.7
__
—
—
Eucalyptus citriodata
Eucalyptus
Ooty
725
9.35
15.4
12.9
10.3
1.0
1.4
8.6
7.6
6.3
3.0
2.4
2.0
—
__
—
Eucatytus tereticornis
Eucalyptus
Chennai
777
11.05
16.7
13.9
11.1
1.0
1.4
9.7
8.6
7.1
3.4
2.6
2.2
m
e
—
GROUP C
Tbizia procera
White sins
U.P
643
9.02
13.4
11.2
8.9
1.0
1.4
8.5
7.6
6.2
4.3
3.3
2.7
i
c
B
Artocarpus lakocha
Lakooch (LAK)
U.P
647
6.14
10.0
8.3
6.7
1.0
1.4
5.3
4.7
3.8
2.8
2.2
1.8
i
—
B
Artocarpus hetaropkyllus
Jack, kathal (KAT)
Chennai
617
9.46
13.9
11.6
9.2
1.0
1.5
9.3
8.3
6.8
4.5
3.5
2.9
i
d
B
(Syn. A. Integrifalia)
Aphanamixis polystachya
PitrajCFTT)
West Bengal
668
8.98
12.3
10.2
8.2
1.1
1.5
8.0
7.1
5.8
4.0
3.1
2.6
i
—
B
(Syn. Amoora rehituka)
Adina cordifolia*
Haldu(HAL)
UP.
663
8.54
13.3
11.1
8.9
1.0
1.4
8.7
7.7
6.3
4.4
3.4
2.8
m
a
B
Anthocephyalus chinensis
Kadam(KAD)
—
485
1.88
9.7
8.1
5.4
0.7
1.0
5.9
5.3
4.3
1.9
1.5
1.2
m
a
—
(Syn. A. Cadamba)
Artocarpus ckaplasha
Chaplash (CHP)
Assam
515
9.11
13.2
11.0
8.8
0.9
1.2
8.5
7.5
6.2
3.6
2.8
2.3
m
d
B
Acacia leucophloea
Hiwar(HIW)
.M.P.
737
7.85
13.4
11.2
9.0
1.0
1.5
7,5
6.7
5.4
4.5
3.5
2.8
_
—
A
Acacia melanoxyione
Black wood
Chennai
630
9.45
13.0
10.8
8.7
1.1
1.5
7.6
6.8
5.5
3.2
2.5
2.0
—
—
—
Acacia mearnsii
Black wattle
Chennai
669
6.10
10.4
8.6
6.9
0.8
1.2
6.0
5.4
4.4
2.3
1.8
1.5
—
—
—
(Syn. A. moUissima)
Accer spp.
Maplej(MAP)
Punjab, U.P
551
7.35
9.9
8.2
6.5
0.9
1.3
5.5
4.9
4.0
2.1
1.7
1.4
m
—
B
Aegia marmalos
Bael (BEL)
U.P
890
8.81
13.5
11.2
9.0
1.4
2.0
8.8
7.8
6.4
6.8
5.3
4.3
m
—
B
(Syn. Intsia bijuga)
Afzelia bijuga
—
Andaman
705
9.16
13.2
11.0
8,8
1.1
1.5
7.9
7.1
5.8
4.0
3.1
2.6
—
—
—
AUanthus grandis
Gokul (GOK)
W. Bengal
404
7.94
8.3
6.9
5.5
0.6
0.8
5.3
4.7
3.9
1.1
0.9
0.7
m
—
C
Anogeissus pendula
Kardhai(KAH)
U.P
929
9.75
17.0
14.2
11.4
1.3
1.8
9.8
8.7
7.1
6.5
5.1
4.2
m
—
A
Areca nut
—
Kerala
833
9.48
15.2
12.7
10.2
1.2
1.6
10.8
9.6
7.8
7.3
5.7
4.7
—
__
—
32
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(ID
(12)
(13)
(14)
(15)
(16)
(17)
(18)
(19)
H
t/3
Albizia lucida
—
Arunachal,
A. P.
566
8.51
10.7
8.9
7.1
8.2
1.2
7.3
6.3
5.3
2.3
1.8
1.5
—
—
—
Azadirachta indica
Neem (NEE)
U.P.
836
8.52
14.6
12.1
9.7
1.3
1.8
10.0
8.9
7.3
5.0
3.9
3.2
—
—
—
H
Boswellia seriata
Salai (SAA)
Bihar
551
7,21
9.4
7.9
6.3
0.7
1.1
5.5
4.9
4.0
2.1
1.6
1.3
I
e
C
Bridelia retusa
Kassi (KAS)
Bihar
584
9.42
11.6
9.7
7.7
0.9
1.3
7.1
6.3
5.1
4.0
3.1
2.6
I
e
B
Betula Inoides
Birch (BIR)
West Bengal
625
9.23
9.6
8.0
6.4
0.8
1.1
5.7
5.0
4.1
2.2
1.7
1.4
—
—
B .
8
1
Bischofia javanica
Uriam Bishopwood
(URD
Chennai
769
8.84
9.6
8.2
6.5
0.8
1.1
5.9
5.3
4.3
3.6
2.8
2.3
m
—
A
Burserra serrata
(Syn. Protium serratum)
Muntenga(MUR)
A.P.
756
1.17
15.5
13.3
10.5
0.9
1.3
10.1
9.0
7.4
5.3
4.1
3.4
n
c
—
Careya arbersa
Kumbi (KUM)
U.P.
889
8.37
13.1
10.9
8.8
1.0
1.5
7.7
6.8
5.6
5.3
4.1
3.4
i
e
A
Cedrus deodara
Deodar (DEO)
H.P.
557
9.48
10.2
8.7
7.2
0.7
1.0
7.8
6.9
5.7
2.7
2.1
1.7
i
c
C
o
2
Cupressus torulosa
Cypress (CYP)
U.P.
506
8.41
8.8
7.6
6.2
0.6
0,8
6.9
6.2
5.0
2.4
1.8
1.5
i
e
C
Ul
H
w
w
Castanopsis hystrix
Indian chestnut
(ICH)
West Bengal
624
9.85
10.6
8.8
7.0
0.8
1.2
6.4
5.7
4.6
2.7
2.1
1.7
n
b
B
Chukrasia vclutina
(Syn. C. Tabularis)
Chickrassy (CHI)
West Bengal
666
8.35
11.8
9.8
7.9
1.1
1.5
7.1
6.3
5.2
3.9
3.1
2.5
n
c
B
>
Calophyllum wightianum
Poon (POO)
Maharashtra
689
8.68
13.5
11.2
9.0
1.0
1.4
8.7
7.8
6.4
4.0
3.1
2.5
n
—
B
a
w
Canarium strictum
White dhup
Assam
569
10.54
10.1
8.4
6.7
0.7
1.1
6.2
5.5
4.5
2.1
1.6
1.3
m
—
C
Chlorophora excelsa
—
w
o
o
Cocosnucifera
Coconut (COC)
Kerala
761
7.34
9.2
7.7
6.1
0.7
1.1
9.5
8.4
6.9
3.9
3.0
2.5
—
—
_
Dalbergia latifolia
Rosewood (ROS)
M.P.
884
8.39
12.9
10.8
8.6
1.1
1.6
8.0
7.1
5.8
4.2
3.3
2.7
i
—
B
Dalbergia sissee
Sisso (SIS)
Punjab
799
7.14
12.8
10,7
8.5
1.3
1.8
8.2
7.3
6.0
4.2
3.3
2.7
i
e
B
H
Dillemia indica
Dillenia (DIL)
West Bengal
617
8.61
12.1
10.0
8.0
0.8
1.2
7.3
6.5
5.3
2.7
2.1
1.7
in
a
B
i
Dillenia pentagyne
Dillenia (DIL)
West Bengal
622
7.56
11.8
9.9
7.9
0.9
1.3
7.1
6.3
5.2
3.5
2.7
2.2
m
d
B
Diospyres melanoxylon
Ebony (EBO)
Maharashtra
818
7.69
10.9
9.1
7.3
0.9
1.2
7.0
6.2
5.1
.3.3
2.6
2.1
n
—
A
Duabanga grandiflora
(Syn, D. Sonneratioides)
Lampati (LAP)
West Bengal
485
8.38
9.8
8.2
6.5
0.6
0.9
6.4
5.7
4.7
1.8
1.4
1.1
m
c
C
Elesocarpus tuberculatus
Rudrak (R&D)
Chennai
466
8.74
9.7
8.1
6.4
0.7
1.0
6.3
5.6
4.6
2.0
1.5
1.3
—
—
C
Eucalyptus hybrid
Mysore gum (MGU)
Chennai
753
6.00
10.2
8.5
6.8
0.9
1.2
7.3
6.5
5.3
4.0
3.1
2.5
m
e
—
Calitres rhomboidea
(Syn<Frenela rhomboidea)
—
Chennai
607
6.48
9.2
7.7
6.1
0.7
1.0
6.9
6.1
5.0
4.0
3.1
2.6
—
—
—
Garuga pinnaia
Garuga (GAU)
U.P.
571
7.58
11.7
9.7
7.8
1.0
1.5
7.2
6.4
5.3
3.4
2.6
2.1
i
e
B
gGmeline arborea
Gamari(GAM)
U.P.
501
7.02
9.8
8.2
6.6
0.8
1.2
5.7
5.0
4.1
4.2
3,2
2 J
i
e
B
Gardenia latifolia
Gaidenia(GAI)
M.P.
705
7.13
14.1
11.7
9.4
1.2
1,7
8,4
7.4
6.1
4.6
3.6
3.0
—
—
—
Hardwickis binata
Anjan(ANJ)
M.P.
852
6.64
14.1
11.8
9,4
1.3
1.8
9.0
8.0
6.5
7.4
5.6
A3
i
e
—
h*
Heloptelea integrifolia
Kanju(KAN)
U.P.
592
7.46
12.0
10.0
8.0
0.9
1.3
6.7
6.0
4.9
2.8
2.2
1.8
m
b
B
u>
Table 1 — Continued
i
i
c
o
1
s
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
(16)
(17)
(18)
(19) ■
Heterrophragma rexburghii
Palang (PAL)
M.R
616
8.69
12.3
10.2
8.2
0.7
1.0
7.9
7.0
5.7
3.4
2.6
2.1
—
—
—
Juglans spp.
Walnut (WAL)
U.P.
565
9.00
9.9
8.3
6.6
0.9
1.2
5.8
5.2
4.2
2.2
1.7
1.4
m
_
B
Lagerstrosrma speciosa
Jarul (JAAR)
N. Andaman
622
8.53
12.1
10.1
8.1
0.8
1.8
7.7
6.8
5.6
3.4
2.6
2.2
n
e
B
(Syn. L. flesregihal)
Lannea grandis
Jhingan (JHI)
U.P.
557
5.63
8.5
7.1
5.7
0.6
0.9
4.9
4.4
3.6
2.2
1.7
1.4
in
e
B
(Syn. Lxoromandelica)
Leucanena leucocephala
Subabul(SUB)
U.P.
673
6.32
11.6
9.7
7.8
1.0
1.5
7.4
6.6
5.4
3.8
3.0
2.4
—
—
Lophopatalum wightianum
Banati (BAN)
Chennai
460
733
8.5
7.5
5.6
0.5
0.8
5.3
4.7
3.8
1.8
1.4
1.1
in
—
C
Madhuca longifolia varlatifoHa Mahua (MAU)
M.P.
936
8.82
13.0
10.8
8.7
1.0
1.4
7.5
6.7
5.5
6.3
4.9
4.0
i
e
A
(Syn. Bassia latifolia)
Mangifera indica
Mango, Aam (MAN)
Orissa
661
9.12
12.2
10.2
8.2
1.0
1.4
7.3
6.5
5.3
3.1
2.4
2.0
m
a
C
Machilus macrantha
Machilus (MAC)
Chennai
521
7.63
10.2
8.5
6.8
0.7
1.0
6.3
5.6
4.6
2.4
1.9
1.5
in
e
B
Mallotus philippinensis
Raini (RAI)
U.P.
662
7.51
10.8
9.0
7.2
1.0
1.4
6.0
5.4
4.4
2.9
2.3
1.8
in
—
B
Manglietia insignia
—
Assam
449
10.37
10.9
9.1
7.3
0.7
1.0
8.0
7.1
5.8
3.4
2.6
2.1
—
—
—
Michelia montana
Champ (CHM)
West Bengal
512
8.25
10.9
9.1
7.3
0.7
1.0
6.6
5.9
4.8
2.8
2.2
1.8
i
—
B
Mitragyna pervifolia
Kaim(KAI)
U.P.
651
7.82
12.6
10.5
8.4
1.0
1.5
7.9
7.0
5.7
3.7
2.9
2.4
in
b
B
(Syn. Stephagyne pervifolia)
Michelia excelsa
Champ (CHM)
West Bengal
513
10.12
9.8
8.2
6.5
0.7
1.0
6.1
5.5
4.5
1.6
1.3
1.0
n
e
B
Miliusa velutnia
Domsal (DOM)
U.P.
747
7.92
11.7
9.7
7.8
1.1
1.6
7.0
6.3
5.1
3.7
2.9
2.4
m
—
—
Moms alba
Mulberry (MUL)
U.P.
743
8.20
11.8
9.8
7.9
1.0
1.4
6.6
5.8
4.8
3.8
2.9
2.4
n
__
B
Moms serrata
Mulberry (MUL)
H.R
657
7.03
10.2
8.5
6.8
0.9
1.3
5.6
5.0
4.1
2.6
2.0
1.6
m
—
B
Moms laevigata
Bola (BOL)
Andaman
588
8.61
12.3
10.2
8.2
1.0
1.5
7.2
6.4
5.3
3.3
2.5
2.1
—
—
B
Ougeinia eejeinensis
Sandan(SAD)
MR
784
8.54
13.3
11.1
8.9
1.2
1,7
8.5
7.5
6.2
5.1
3.9
3.2
i
—
B
(Syn, 0. delbergioides)
Phoebe hainesiana
Bonsum(BOH)
Assam
566
9.50
13.2
11.0
8.8
0.8
1J2
8.8
7.8
6.4
2.8
2.1
1.8
n
c
B
Pinus roxburghii
Chir(CHR)
U.R
525
9.82
8.5
7.3
6.0
0.6
0.9
6.0
5.3
4.4
2.0
1.5
1.3
m
b
C
(Syn, R fangijvlia)
"V
-
/
Pinus wallichiana
Kail(KAL)
515
6.80
6.6
5.6
5.0
0.6
0.8
5.2
4.6
3.8
1.7
1.3
1.0
n
c
C
Phoebe goalperansis
Bonsum (BOH)
Assam
511
7.65
9.7
8.1
6.5
0,7
1.0
6.6
5.9
4.8
2.2
1.7
1.4
n
c
B
Parretiopsis jacquementiena
RohuiParrotia
H.R
761
5.77
12.5
10.4
8.3
1.2
1.7
6.8
6.1
5.0
4.0
3.1
2.5
in
—
B
Pinus kesia
Khasi pine (KPI)
North East
513
7.38
8.9
7.4
5.9
0.6
0.7
5.8
5.2
4.3
1.5
1.2
1.0
m
a
B
(Syn. Pinus insularis)
Pistacia mtegerrima
Kikarsinghi
J&K
881
7.32
13.1
10.9
8J
1.2
1.7
8.0
7.1
5,8
4.3
3.4
2.8
—
. —
■ —
Podocarpus nerrifolius
thitmin(THT)
S. Andaman
533
9.41
12.5
10,4
8.3
6.1
0.9
8.0
7.1
5.8
2.6
2.0
1.6
n
—
—
Polyalthia fragrances
Debdaru(DEB)
(Nedunar)
Maharashtra
752
9.15
11.9
9,9f
7.9
0.8
1,2
6.7
6.0
4.9
3.0
2.3
1.9
m
B
Polyalthia coreoides
M.P.
700
9.29 13.2 11.0 8.8 1.0 1.4 7.1 6.3 5.2 3.2 2.5 2.0 —
(1)
(2)
(3)
(4)
(5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17)
(18)
(19)
Prunus napeulensis
Arupati
West Bengal
Pterespermum acerifolium
Hattipaila (HAT)
West Bengal
Qucrcus spp.
Oak
North East
Raderomachera xylocarpe Vedankonnai
(Syn. Sterosperam xylocarpum)
Chennai
Schleichera oleosa
(Syn. S. trijuga)
Kusum (KUS)
Bihar
Schima wallichii
Chilauni (CHL)
West Bengal
Shotea assamica
Makai (MAK)
Assam
Sonneralia apetale
Keora(KEO)
West Bengal
Stereospermum suaveolans
Padri (PAD)
U.P.
Tactona grandis
Teak (TEA)
M.P.
Terminalia arjuna
Aijun (ARJ)
Bihar
Terminalia myriocarpa
Hollock (HOC)
Assam
Terminalia procera
White bombwae
(WBO)
N.Andaman
Taxus buccata
Yew (YEW)
West Bengal
Tamarindus indica
Imli(IML)
Chennai
Toena ciliata
Toon (TOO)
U.P.
Vateria indica
Vellapine (VEL)
Chennai
Aeculas indica
Horse chestnut
(HCH)
U.P.
Borassus flabelsfer
Tad (Palmyra)
(TAD)
A.P.
Eucalyptus cemaldulensis
Eucalyptus
Karnataka
Eucalyptus camaldulenis
Eucalyptus
U.P.
Eucalyptus pitularia
Eucalyptus
.T.N.
Eucalyptus propingus
Eucalyptus
T.N.
Eucalyptus saligna
Eucalyptus
UP.
548 9.41 104.4 8.7 69.6 0.9 1.2 6.7 6.0 4.9 2.4 1.9 1.6
607 9.55 13.5 11.3 9.0 0.9 1.2 8.7 7.7 6.3 3.2 2.5 2.0
657 11.65 11.4 9.5 7.6 0.8 1.2 6.7 5.9 4.8 2.0 1.6 1.3
696 8.52 13.2 11.0 8.8 1.1 1.5 9.0 8.0 6.6 4.3 3.3 2.7
1032 12.12 15.5 13.0 10.4 1.5 2.1 10.9 9.7 7.9 6.1 4.2 3.9
III
c
B
II
c
B
11
a
693
9.57
11.1
9.3
7.4
0.9
1.3
6.6
5.9
4.8
2.3
1.8
1.4
in
d
B
548
9.27
11.1
9.2
7.4
0.9
1.3
7.1
6.3
5.2
2.9
2.2
1.8
ni
c
B
617
8.63
12.8
10.7
8.5
0.9
1.3
7.4
6.6
5,4
4.8
3.7
3.0
ii
—
B
721
8.86
13.3
11.1
8.9
0.9
1.3
7.3
7.0
5.7
3.5
2.7
2.2
m
—
B
617
8.49
12.8
10.7
8.5
0.8
1.3
7.9
7.0
5.7
4.0
3.1
2.6
i
e
B
794
7.71
12.2
10.2
8.2
1.1
1.6
7.4
6.6
5.4
5.2
4.1
3.3
n
b
B
615
9.62
11.9
9.9
8.0
0.9
1.2
7.6
6.7
5.5
2.9
2.2
1.8
m
a
B
626
8.99
11.8
9.8
7.9
0.9
1.3
7.2
6.4
5.3
3.0
2.3
1.9
ni
b
B
705
7.79
14.3
11.9
9.5
1.2
1.7
8.7
7.8
6.4
4.7
3.7
3.0
—
913
5.63
11.4
9.5
7.6
1.2
1.7
7.0
6.2
5.1
5.3
4.1
3.4
—
__
B
487
6.40
8.7
7.3
5.8
0.7
1.0
5.4
4.8
3.9
2.4
1.8
1.5
ii
c
B
535
10.95
11.5
9.6
7.6
0.7
1.1
7.5
6.7
5.5
2.3
1.8
1.4
m
e
C
484
7.55
8.5
7.1
5.7
0.8
1.1
4.8
4.2
3.5
1.8
1.4
1.1
—
—
B
838
8.79
10.5
8.8
7.0
0.7
1.0
10.0
8.8
7.2
4.7
3.6
2.7
—
—
—
804
9.53
12.8
10,6
8.5
0.8
1.1
7.2
6.4
5.2
3.5
2.7
2.2
—
—
A
781
7.03
12.4
10.4
8.3
1.1
1.6
7.9
7.0
5.7
3.5
2.8
2.3
—
—
A
713
9.22
14.8
12.3
11.1
1.0
1.4
8.5
7.6
6.2
2.8
2.2
1.8
—
—
A
584
7.93
12.8
10.7
8.5
0.8
1.2
8.0
5.4
4.4
2.5
1.9
1.6
—
—
A
819
8.24
11.5
9.6
7.6
1.5
2.1
8.2
7.3
6.0
6.2
4.8
4.0
—
—
A
* Species thus marked and tested from other localities show higher strength to enable their categorization in higher group.
For Example
i) Sal tested from West Bengal, Bihar, U.P. and Assam can be classified as Group *A' species;
ii) Haldu tested from Bihar can be classified as Group 'B' species;
iii) Moms laevigate (Bole) of Assam can be classified in Group 'B' species.
tn
Table 1 — Concluded
2
H
s
o
5
o
o
o
o
w
o
f Classification for preservation based on durability tests, etc.
Class
I - Average life more than 120 months;
II - Average life 60 months and above but less than 120 months; and
III - Average life less than 60 months.
$ Treatability Grades
a - Heartwood easily treatable;
b -' Heartwood treatable, but complete penetration not always obtained; in case where the least dimension is more than 60 mm;
c - Heartwood only partially treatable;
d - Heartwood refractory to treatment; and
e - Heartwood very refractory to treatment, penetration of preservative being practically nil even from the ends;
Data based on strength properties at three years of age of tree.
§ Classifications based on seasoning behaviour of timber and refractoriness w.r.t. cracking, spliting and drying rate:
A - Highly refractory (slow and difficulty to season free from surface and end cracking);
B - Moderately refractory (may be seasoned free from surface and end cracking within reasonably short periods, given a little protection against rapid drying conditions); and
C - Non-refractory may be rapidly seasoned free from surface and end-cracking even in the open air and sun. If not rapidly dried, they develop blue stain and mould on the surface.
Table 2 Permissible Lateral Strengths (in Double Shear) of Nails 3.55 mm Dia, 80 mm Long
(Clause 4.3)
SI
Species
of Wood
For Permanent Construction
For Temporary Structures
No.
Strength per
Nail
Strength per Nail (for Both
"
*
t^
"*\
Lengthening Joints and
Botanical Name
Trade Name
Lengthening
Joints
Node
Joints
Node Joints)
Nx 10 2
NxlO 2
Nx 10 2
(1)
(2)
(3)
(4)
(5)
(6)
1.
Albies pirdrow l)
Fir
8
2
12
2.
Acacia nilotica
Babul
15
11
34
3,
A c ro ca rp us fraxin ifo Hit s
Mundani
18
9,5
19.5
4.
Adina cordifolia
Haldu
23.5
10
22
z .
Alhizia lebbeck
Kokko
20
7
24
6.
Albizia odoratissima
Kala Siris
14
5
22
7.
Anogeissus latifolia
Axlewood
20
10
29
8.
Aphanamixis polystachya
Pitraj
19
9
19
9.
Calophyllum spp. V)
Poon
16
9
21
10.
Canarium euphyllum
White dhup
9
8
10.5
II.
Castanopsis spp.
Indian chestnut
18
10.5
23.5
12.
Cedrus deodar a l)
Deodar
9
4
15
13.
Chukrasia tabularis
Chikrassy
24
8
27
14.
Cinnamomum spp. l)
Cinnomon
12
9
13
15.
Cupressus torulosa
Cypress
6
5
18
16.
Dipterocarpus macrocarpus
Hollong
17
7
20
17.
Dipterocarpus spp.
Gurjan
19
9
19
18.
Dillenia pertagyna
Dillenia
16.5
12
16
19.
Diospyros melanoxylon
Ebony
26.5
10
30.5
20.
Eucalyptus eugenioides
Eucalyptus
17
10
30
21.
Grewia tilifolia V)
Dhaman
13
5
24
22.
Lagerstroemia spp.
Jarul
24.5
21.5
22.5
23.
Hopea parviflora
Hopea
31.5
13
28.5
24.
Ijigerstroemia spp. l)
Lendi
19
5
26
25.
Mangifera indica
Mango
11
9
16
26.
Maniltoa polyandra
Ping
26
23.5
32
27.
Mesuaferrea
Mesua
26
8
41
28.
Michelia spp.
Champ
13
9
20
29.
Millingtonia spp. X)
__
10.5
6
17
30.
Morus alba
Mulberry
13
10.5
22.5
31.
Melia azedarach
Persian lilac (bakain)
10.5
2.5
9
32.
Ougeinia oojeinensis
Sandan
17
11
18
33.
Phoebe spp. l)
Bon sum
12
6
13
34.
Pinus roxburghii 1 '
Chir
11
10
16
35.
Pinus wallichiana ]
Kail
7
3
9
36.
Pterocarpus marsupium
Bijasal
15
12
27
37.
Pterocarpus dalbergiodes
Pauduak
19
14
23
38.
Planchonia andamanica
Red bombwe
14
13
29
39.
Quercus spp.
Oak
11
11
27
40.
Scheichera cleosa
Kusum
23
16
40
41.
Shorea roubusta
Sal (M.P.)
23
15.5
19.5
42.
Shorea robusta
Sal
10
5
19
43.
Ste reo spenmum
Padriwood
16
8
19.5
44.
Syzygium spp.
Jamum
15
12
25
45.
Tectona grandis
Teak
14
8
13
46.
Terminalia Bellirica
Bahera
10
10
14
47.
Terminalia biolata
White chuglam
18
9
21
48.
Terminalia procera
Badarn
18
10.5
20
49.
Terminalia manii l)
Black chuglam
23
10
33
50.
Terminalia myriocarpa
Hollock
13
10
19
51.
Terminalia alata
Sain
16
16
29
52.
Toona spp.
Toona
10
8
21
53.
Xylia xylacarpa
Irul
23
6
33
54.
Toona ciliata
Toon
16
9
21
NOTES
1 Nails of 3.55 mm diameter are most commonly used. The above values can also be used for 4 mm diameter 100 mm long nails.
2 The values in N are approximate converted values from kgf. For exact conversion the value is 1 kgf = 9.806 65 N.
n Species requiring no preboring for nail penetration.
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
17
Table 3 Permissible Lateral Strengths (in Double Shear) of Nails 5.00 mm Dia,
125 mm and 150 mm Long
(Clause 4.3)
SI
Species of Wood
For Permanent Construction
For Temporary Structures
No.
—*^
Strength
per Nail
Strength per Nail (for
Both Lengthening Joints
^* —
-s
Botanical Name
Trade Name
Lengthening Joints
Node Joints
and Node Joints)
Nx 10 2
Nx 10 2
Nx 10 2
(1)
(2)
(3)
(4)
(5)
(6)
1.
Abies pindrow l)
Fir
16.5
4.5
21
2.
Acacia catechu
Khair
42
25
71.5
3.
Acacia nilotica [)
Babul
27
13.5
53
4.
Alibizia procera
Safed siris
35
18
—
5.
Alibizia odoratissima l)
Kala siris
27.5
17.5
45
6.
Alstonia scholaris
Chatian
9.5
5.5
27
7.
Anogeissus latifolia
Axlewood
22.5
13
46.5
8.
Cupressus torulosa
Cypress
20
7
27
9.
Cullenia rosayroana
Karani
11
9.5
30
10.
Dalbergia sissoo
Sissoo
17
15
43
11.
Diptrocarous spp.
Gurjan
19.5
9.5
33
12.
Hardwickia binata
Anjan
32
19
59
13.
Hopea perviflora
Hopea
60.5
25
61.5
14
Holoptelea integrifolia
Kanju
18
12.5
37.5
15.
Mangifera indica l)
Mango
22.5
15
32
16.
Mesua ferrea
Mesua
24
15.5
57.5
17.
Michelia champaca ])
Champ
26
12.5
39
18.
Pterocarpus marsupium
Bijasal
20.5
15
43
19.
Pinus roxburghii l)
Chir
9
6
24
20.
Shorea robusta (U.P.)
Sal
19.5
17
37
21.
Shore a robusta
Sal
30.5
20
41
22.
Schleichera cleosa
Kusum
15
14
55
23.
Stereo spimum personatum
Padriwood
22
8
34
24.
Syzygium cumini
Jamum
18
14.5
38.5
25.
Terminalia myriocarpa
Hollock
27.5
9
41
2b.
Tectona grandis
Teak
28
13
30
27.
Hopea utilis
Karung kangoo
31
10
58
28.
Phoebe spp 1}
Bonsum
20
7.5
30
NOTES
1 Nails of 5.00 mm diameter are most commonly used.
2 The values in N are approximate converted values from kgf. For exact conversion the value is 1 kgf = 9.806 65 N.
1} Species requires no preboring for nail penetration.
Table 4 Permissible Percentage Moisture Content Values
(Clause 4.4)
SI
No.
(1)
Use
(2)
Zones (see Notel
i
I
II
m
IV
(3)
(4)
(5)
(6)
12
14
17
20
10
12
14
16
8
10
12
14
8
10
10
12
12
12
14
16
i)
ii)
iii)
iv)
Structural elements
Doors and windows
a) 50 mm and above in thickness
b) Thinner than 50 mm
Flooring strips for general purposes
Flooring strips for tea gardens
NOTE — The country has been broadly divided into the following four zones based on the humidity variations in the country:
Zone I — Average annual relative humidity less than 40 percent.
Zone II — Average annual relative humidity 40 to 50 percent.
Zone III — Average annual relative humidity 50 to 67 percent.
Zone IV — Average annual relative humidity more than 67 percent.
For detailed zonal classification, tolerances, etc reference may be made to good practice [6-3 A(4)].
18
NATIONAL BUILDING CODE OF INDIA
Table 5 Preferred Cut Sizes of Structural Timbers for Roof Trusses
(Span from 3 m to 20 m)
(Clause 4.5.1)
Thickness
Width
mm
mm
(t)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
20
40
50
60
80
100
—
—
—
25
40
50
60
80
100
120
140
160
30
40
50
60
80
100
120
140
160
35
—
—
60
80
100
120
140
160
40
—
—
60
80
100
120
140
160
50
—
—
60
80
100
120
140
160
60
—
—
—
80
100
120
140
160
80
—
—
—
—
100
120
140
160
NOTES
1 For truss spans marginally above 20 m, preferred cut sizes of structural timber may be allowed.
2 Preferred lengths of timber: 1, 1.5, 2, 2.5 and 3 m.
Table 6 Preferred Cut Sizes of Structural Timber for Roof Purlins,
Rafters, Floor Beams, Etc
(Clause 4.5.1)
Thickness
mm
(1)
Width
mm
(2)
(3)
(4)
(5)
(6)
(7)
(8)
50
60
80
100
80
80
100
100
100
120
120
120
140
140
140
140
160
160
160
180
NOTE — Preferred lengths of timber: 1.5, 2, 2.5 and 3 m.
200
Table 7 Preferred Cut Sizes of Structural Timbers for Partition
Framing and Covering, and for Centering
(Clause 4.5.1)
Thickness
Width
mm
mm
(1)
(2)
(3)
(4)
(5)
(6)
(7)
>>
(9)
(10)
10
40
50
60
80
—
—
■ —
—
— .
15
40
50
60
80
100
_
__
■■■_
—
20
40
50
60
80
100
120
160
200
—
25
40
50
60
80
100
120
160
200
240
30
40
50
60
80
100
120
160
200
240
40
40
—
60
80
100
120
160
200
240
50
—
50
—
80
100
120
160
200
240
60
—
—
60
80
100
120
160
200
240
80
—
—
—
80
100
120
160
200
240
NOTE-
- Preferred lengths
of timber: 0.5, 1
1, 1.5, 2, 2.5 and 3 m.
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
19
Table 8 Permissible Defects for Cut Sizes of Timber for Structural Use
(Clauses 4.6 A and 4.6.2.2)
All dimensions in millimetres.
SI
Defects
Select Grade
Grade I
Grade II
No.
(1)
(2)
(3)
(4)
(5)
i) Wane Shall be permissible at its deepest
portion up to a limit of 1/8 of the
width of the surface on which it
Shall be permissible at its deepest
portion up to a limit of 1/6 of the
width of the surface on which it
Shall be permissible at its deepest
portion up to a limit of 1/4 of the
width of the surface on which it
li ) Worm holes
Other than those due
to powder
Other than those due to powde
r Other than those due to powder post
post beetles are permissible
post beetles
are permissible
beetles are permissible
iii) Slope of grain
Shall not be more than 1 in 20
Shall not be
more than 1 in 15
Shall not be more than 1 in 1 2
iv) Live knots:
Width of
Wide Face.
Permissible Maximum Size
s Live Knot on
of
Permissible Maximum Size of
Live Knot on
Permissible Maximum Size of
Live Knot on
of C.ut Size*
.^-*w.
^*w
*^.
of Timber
Narrow faces and
l A of the width
Remaining
central half of
Narrow faces and
l A of the width
Remaining
central half of
Narrow faces and
l A of the width
Remaining central
half of the width
Max
face
close to
the width of the
face
close to
the width of the
face close
to
of the wide faces
edges of cut size
of timber
wide faces
edges of cut size
of timber
wide faces
edges of cut size
of timber
(1)
(2)
(3)
(4)
(5)
(6)
(7)
75
10
10
19
19
29
30
100
13
13
25
25
38
39
150
19
19
38
38
57
57
200
22
25
44
50
66
75
250
25
29
50
57
66
87
300
27
38
54
75
81
114
350
29
41
57
81
87
123
400
32
44
63
87
96
132
450
33
47
66
93
99
141
500
35
50
69
100
105
150
550
36
52
72
103
108
156
600
38
53
75
106
114
159
v) Checks and shakes:
Width of the Fat
the Timber
:eof
Permissible Depth
Max
Permissible Depth
Max
Permissible Depth
Max
Max
(1)
(2)
(3)
(4)
75
12
25
36
100
18
35
54
150
25
50
75
200
33
65
99
250
40
81
120
300
50
100
150
350
57
115
171
400
66
131
198
450
76
150
225
500
83
165
249
550
90
181
270
600
100
200
300
20
NATIONAL BUILDING CODE OF INDIA
Allowable stresses or loads on joints and fasteners shall
be determined in accordance with recognized
principles. Common mechanical fastenings are of bar
type such as nails and spikes, wood screws and bolts,
and timber connectors including metallic rings or
wooden disc-dowels. Chemical fastenings include
synthetic adhesives for structural applications.
5 PERMISSIBLE STRESSES
5.1 Fundamental stress values of different groups of
timber are determined on small clear specimen
according to good practice [6-3A(l)]. These values are
then divided by the appropriate factors of safety to
obtain the permissible stresses. In these values, are then
applied, appropriate safety factors given in the relevant
table of the accepted standard [6-3A(5)] to obtain the
permissible stress.
5.2 The permissible stresses for Groups A, B and C
for different locations applicable to Grade I structural
timber shall be as given in Table 9 provided that the
following conditions are satisfied:
a) The timbers should be of high or moderate
durability and be given the suitable treatment
where necessary.
b) Timber of low durability shall be used after
proper preservative treatment to good practice
[6-3 A(6)], and
c) The loads should be continuous and
permanent and not of impact type.
Table 9 Minimum Permissible Stress Limits
(N/mm 2 ) in Three Groups of Structural Timbers
(for Grade I Material)
(Clauses 5.2 and 5.3)
SI
No.
Strength
Character
Location of
Use
Group
A
Group
B
Group
C
(1)
(2)
(3)
(4)
(5)
(6)
i)
Bending and
tension along
grain
Inside l)
18.0
12.0
8.5
ii)
Shear 2)
Horizontal
All locations
1.05
0.64
0.49
Along grain
All locations
15
0,91
0.70
iii)
Compression
parallel to grain
Inside 1}
11.7
7.8
4.9
iv)
Compression
perpendicular
to grain
Inside 1}
4.0
2.5
1.1
v)
Modulus of
elasticity
(xl0 3 N/mm 2 )
All locations
and grade
12.6
9.8
5.6
1) For working stresses for other locations of use, that is, outside
and wet, generally factors of 5/6 and 2/3 are applied.
2) The values of horizontal shear to be used only for beams. In all
other cases shear along grain to be used.
5.3 The permissible stresses (excepting E) given in
Table 9 shall be multiplied by the following factors to
obtain the permissible stresses for other grades
provided that the conditions laid down in 5.2 are
satisfied:
a) For Select Grade Timber
b) For Grade II Timber
1.16
0.84
5.3.1 When low durability timbers are to be used
[see 5.2(b)] on outside locations, the permissible
stresses for all grades of timber, arrived at by 5.2
and 5.3 shall be multiplied by 0.80.
5.4 Modification Factors for Permissible Stresses
5.4.1 Due to Change in Slope of Grain
When the timber has not been graded and has major
defects like slope of grain, knots and checks or shakes
but not beyond permissible value, the permissible stress
given in Table 1 shall be multiplied by modification
factor K x for different slopes of grain as given in
Table 10.
Table 10 Modifications Factor K x to Allow
for Change in Slope of Grain
(Clause 5.4.1)
Slope
(1)
Modification Factor K\
A
<- —^
Strength of Beams, Strength of
Joists and Ties Posts or Columns
(2)
(3)
linlO
0.80
linl2
0.90
linl4
0.98
in 15 and flatter
1.00
0.74
0.82
0.87
1.00
NOTE — For intermediary slopes of grains, values of
modification factor may be obtained by interpolation.
5.4.2 Due to Duration of Load
For different durations of design load, the permissible
stresses given in Table 1 shall be multiplied by the
modification factor K 2 given in Table 11.
NOTE — The strength properties of timber under load are time-
dependent. A _,
Table 11 Modifications Factor^, for Change
in Duration of Loading
(ClauseSAl)
Duration of Loading
(1)
Modification Factor K 2
(2)
Continuous (Normal)
Two months
Seven days
Wind and earthquake
Instantaneous or impact
1.0
1.15
1.25
1.33
2.00
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
21
5.4.2.1 The factor AT 2 is applicable to modulus of
elasticity when used to design timber columns,
otherwise they do not apply thereto.
5.4.2.2 If there are several duration of loads (in
addition to the continuous) to be considered, the
modification factor shall be based on the shortest
duration load in the combination, that is, the one
yielding the largest increase in the permissible stresses,
provided the designed section is found adequate for a
combination of other larger duration loads.
[Explanation: In any structural timber design for dead
loads, snow loads and wind or earthquake forces,
members may be designed on the basis of total of
stresses due to dead, snow and wind loads using
K 2 - 1. 33, factorfor the permissible stress (of Table 1)
to accommodate the wind load, that is, the shortest of
duration and giving the largest increase in the
permissible stresses. The section thus found is checked
to meet the requirements based on dead loads alone
with modification K 2 = 1.00].
5.4.2.3 Modification factor K 2 shall also be applied to
allowable loads for mechanical fasteners in design of
joints, when the wood and not the strength of metal
determines the load capacity.
6 DESIGN CONSIDERATIONS
6.1 All structural members, assemblies or framework
in a building, in combination with the floors, walls and
other structural parts of the building shall be capable
of sustaining, with due stability and stiffness the whole
dead and imposed loadings as per Part 6 'Structural
Design, Section 1 Loads, Forces and Effects', without
exceeding the limits of relevant stresses specified in
this Section.
6.2 Buildings shall be designed for all dead and
imposed loads or forces assumed to come upon them
during construction or use, including uplifts or
horizontal forces from wind and forces from
earthquakes or other loadings. Structural members and
their connections shall be proportioned to provide a
sound and stable structure with adequate strength and
stiffness. Wooden components in construction
generally include panels for sheathing and diaphragms,
siding, beams, girder, columns, light framings,
masonry wall and joist construction, heavy-frames,
glued laminated structural members, structural
sandwiches, prefabricated panels, lamella arches, portal
frames and other auxiliary constructions.
6.3 Net Section
6.3.1 The net section is obtained by deducting from
the gross sectional area of timber the projected area of
all material removed by boring, grooving or other
means at critical plane. In case of nailing, the area of
the prebored hole shall not be taken into account for
this purpose.
6.3.2 The net section used in calculating load carrying
capacity of a member shall be at least net section
determined as above by passing a plane or a series of
connected planes transversely through the members.
6.3.3 Notches shall be in no case remove more than
one quarter of the section.
6.3.4 In the design of an intermediate or a long column,
gross sectionshall be used in calculating load carrying
capacity of the column.
6.4 Loads
6.4.1 The loads shall conform to those given in Part 6
'Structural Design, Section 1 Loads, Forces and Effects'.
6.4.2 The worst combination and location of loads
shall be considered for design. Wind and seismic forces
shall not be considered to act simultaneously.
6.5 Flexural Members
6.5.1 Such structural members shall be investigated
for the following:
a) Bending strength,
b) Maximum horizontal shear,
c) Stress at the bearings, and
d) Deflection.
6.5.2 Effective Span
The effective span of beams and other flexural
members shall be taken as the distance from face of
supports plus one-half of the required length of bearing
at each end except that for continuous beams and joists
the span may be measured from centre of bearing at
those supports over which the beam is continuous.
6.5.3 Usual formula for flexural strength shall apply
in design:
f =-<f
Jab rj — Jb
6.5.4 Form Factors for Flgxural Members
The following form factors shall be applied to the
bending stress:
a) Rectangular Section — For rectangular
sections, for different depths of beams, the
form factor K^ shall be taken as:
K, -0.81
/ V+89400 A
D 2 +55 000
NOTE — Form factor (K 3 ) shall not be applied for beams having
depth less than or equal to 300 mm.
22
NATIONAL BUILDING CODE OF INDIA
b) Box Beams and I-Beams — For box beams
and I-beams, the form factor K A shall be
obtained by using the formula:
/sT 4 =0.8 + 0.8y
A D 2 +89 400-l A
D 2 + 55 000
where
3^^(6-8^+3/^) (1-^ + 4
c) Solid Circular Cross-Sections — For solid
circular cross sections the form factor K 5 shall
be taken as 1.18.
d) Square Cross-Sections — For square cross-
sections where the load is in the direction of
diagonal, the form factor K 6 shall be taken
as 1.414.
6.5.5 Width
The minimum width of the beam or any flexural
member shall not be less than 50 mm or 1/50 of the
span, whichever is greater.
6.5.6 Depth
The depth of beam or any flexural member shall not
be taken more than three times of its width without
lateral stiffening.
6.5.6.1 Stiffening
All flexural members having a depth exceeding three
times its width or a span exceeding 50 times its width
or both shall be laterally restrained from twisting or
buckling and the distance between such restraints shall
not exceed 50 times its width.
6.5.7 Shear
6.5.7.1 The following formulae shall apply:
a) The maximum horizontal shear, when the load
on a beam moves from the support towards
the centre of the span, and the load is at a
distance of three to four times the depth of
the beam from the support, shall be calculated
from the following general formula:
H =
VQ
lb
b) For rectangular beams:
H= 3V
2bD
c) For notched beams, with tension notch at
supports (see 6.5.7.3):
3VD
H^
SQUARE NOTCH
(BOTTOM SIDE NOTCHED)
d) For notched at upper (compression) face,
where e > D:
SPLAYED NOTCH
(UPPER SIDE NOTCHED)
e) For notched at upper (compression) face,
where e < D:
H =
3V
2b
D
6.5.7.2 For concentrated loads:
V =
\0C(I-x)(xlDf
9/[2 + (jc/Dn
and for uniformly distributed loads,
W
2
1-
2D
After arriving at the value of V, its value will be
substituted in the formula:
H =
V_Q
lb
2bD[
6.5.7.3 In determining the vertical reaction V, the
following deductions in loads may be made:
a) Consideration shall be given to the possible
distribution of load to adjacent parallel beams,
if any;
b) All uniformly distributed loads within a
distance equal to the depth of the beam from
the edge of the^earest support may be
neglected except in case of beam hanging
downwards from a particular support; and
c) All concentrated loads in the vicinity of the
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
23
supports may be reduced by the reduction
factor applicable according to Table 12.
Table 12 Reduction Factor for Concentrated
Loads in the Vicinity of Supports
[Clause 6.5.7.3 (c)]
Distance of Load 1.5 D
from the Nearest or
Support Less
(1)
(2)
2D
(3)
2.5 Z)
(4)
3D
or More
(5)
Reduction factor 0,60 0.40 0.20 No
reduction
NOTE — For intermediate distances, factor may be obtained
by linear interpolation.
6.5.7.4 Unless the local stress is calculated and found
to be within the permissible stress, flexural member
shall not be cut, notched or bored except as follows:
a) Notches may be cut in the top or bottom
neither deeper than one-fifth of the depth of
the beam nor farther from the edge of the
support than one-sixth of the span;
b) Holes not larger in diameter than one quarter
of the depth may be bored in the middle third
of the depth and length; and
c) If holes or notches occur at a distance greater
than three times the depth of the member from
the edge of the nearest support, the net
remaining depth shall be used in determining
the bending strength.
i
^
NET
DEPTH
NOTCHED AT MIDDLE
NOTCHED BEAMS
I
6.5.8 Bearing
6.5.8.1 The ends of flexural members shall be
supported in recesses which provide adequate
ventilation to prevent dry rot and shall not be enclosed.
Flexural members except roof timbers which are
supported directly on masonry or concrete shall have
a length of bearing of not less than 75 mm. Members
supported on corbels, offsets and roof timbers on a
wall shall bear immediately on and be fixed to wall-
plate not less than 75 mm x 40 mm.
6.5.8.2 Timber joists or floor planks shall not be
supported on the top flange of steel beams unless the
bearing stress, calculated on the net bearing as shaped
to fit the beam, is less than the permissible compressive
stress perpendicular to the grain.
6.5.8.3 Bearing stress
6.5.8.3.1 Length and position of bearing
a) At any bearing on the side grain of timber,
the permissible stress in compression
perpendicular to the grain, / cn , is dependent
on the length and position of the bearing.
b) The permissible stresses given in Table 1 for
compression perpendicular to the grain are
also the permissible stresses for any length at
the : ends of a member and for bearings
150 mm or more in length at any other
position.
c) For bearings less than 150 mm in length
located 75 mm or more from the end of a
member as shown in Fig. 1, the permissible
stress may be multiplied by the modification
factor K n given in Table 13.
d) No allowance need be made for the difference
in intensity of the bearing stress due to
bending of a beam.
e) The bearing area should be calculated as the
net area after allowance for the amount of
wane.
f) For bearings stress under a washer or a small
plate, the same coefficient specified in
Table 1 3 may be taken for a bearing with a
length equal to the diameter of the washer or
the width of the small plate.
g) When the direction of stress is at angle to the
direction of the grain in any structural
member, then the permissible bearing stress
in that member shall be calculated by the
following formula:
Jcp X Jen
/c0 =
/cp Sm ^ + /cnCOS 2
6.5.9 Deflection
The deflection in the case of all flexural members
supporting brittle materials like gypsum ceilings,
slates, tiles and asbestos sheets shall not exceed 1/360
of the span. The deflection in the case of other flexural
members shall not exceed 1/240 of the span and 1/150
of the freely hanging length in the case of cantilevers.
6.5.9.1 Usual formula for deflection shall apply;
5 =
KWL
EI
(ignoring deflection due to shear strain)
K- values =1/3 for cantilevers with load at free
end,
1/8 for cantilevers with uniformly
distributed load,
24
NATIONAL BUILDING CODE OF INDIA
Table 13 Modification Factor K 7 for Bearing Stresses
(Clause 6.5.8.3.1)
Length of Bearing, in mm 1 5
Modification Factor, K 7 1 67
25
40
50
75
100
150 or more
1.40
1.25
1.20
1.13
1.10
1.00
75 mm
min
J_50 mm max_
BEARING
Fig. 1 Position of End Bearings
1 /48 for beams supported at both ends
with point load at centre, and
5/384 for beams supported at both
ends with uniformly distributed
load.
6.5.9.2 In order to allow the effect of long duration
loading on E, for checking deflection in case of beams
and joists the effective loads shall be twice the dead
load if timber is initially dry.
6.5.9.3 Self weight of beam shall be considered in
design.
6.6 Columns
NOTE — The formulae given are for columns with pin end
conditions and the length shall be modified suitably with other
end conditions.
6.6.1 Solid Columns
Solid columns shall be classified into short,
intermediate and long columns depending upon their
slenderness ratio (S/d) as follows:
a) Short columns — where Sid does not exceed
11.
b) Intermediate columns — where Sid is between
1 1 and K s , and
c) Long columns — where S/d is greater than
6.6.1.1 For short columns, the permissible
compressive stress shall be calculated as follows:
/ =/
6.6.1.2 For intermediate columns, the permissible
compressive stress is calculated by using the following
formula:
J Q J Cp
1-1
3
\ A
KJ
6.6.1.3 For long columns, the permissible compressive
stress shall be calculated by using the following
formula:
fc
0.329 E
(S/d) 2
6.6.1.4 In case of solid columns of timber, S/d ratio
shall not exceed 50.
6.6.1.5 The permissible load on a column of circular
cross-section shall not exceed that permitted for
a square column of an equivalent cross-sectional
area.
6.6.1.6 For determining Sid ratio of a tapered column,
its least dimension shall be taken as the sum of the
corresponding least dimensions at the small end of the
column and one-third of the difference between this
least dimension at the small end and the corresponding
least dimension at the large end, but in no case shall
the least dimension for the column be taken as more
than one and a half times the least dimension at the
small end. The induced stress at the small end of the
tapered column shall not exceed the permissible
compressive stress in the direction of grain.
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
25
6.6.2 Built-up Columns
6.6.2.1 Box column
Box columns shall be classified into short, intermediate
and long columns as follows:
S
a) Short columns — where , is less
yjdi+dl
than 8;
b) Intermediate columns — where
between 8 and K 9 \ and
S
c) Long columns — where
is
thanK,
yjd*+d 2 2
^dl+d
is greater
6.6.2.2 For short columns, the permissible
compressive stress shall be calculated as follows:
/«»«/«
cp
6.6.2.3 For intermediate columns, the permissible
compressive stress shall be obtained using the
following formula:
Jc "Jcp
/
1-1
3
V
Kyjdi +d x
6.6.2.4 For long columns, the permissible compressive
stress shall be calculated by using the following
formula:
/c
0.329 UE
V
y[d[+d :
6.6.2.5 The following values of U and <?, depending
upon plank thickness (?) in 6.6.2.3 and 6.6.2.4, shall
be used:
t
U
q
mm
25
0.80
1.00
50
0.60
LOO
6.6.3 Spaced Columns
6.6.3.1 The formulae for solid columns as specified
in 6.6.1 are applicable to spaced columns with a
restraint factor of 2.5 or 3, depending upon distances
of end connectors in the column.
NOTE — A restrained factor of 2.5 for location of centroid
group of fasteners at 5/20 from end and 3 for location at 5/10
to 5/20 from end shall be taken.
6.6.3.2 For intermediate spaced column, the
permissible compressive stress shall be:
Jc Jcp
1-1
3
r s
v
yKod
6.6.3.3 For long spaced columns, the formula shall
be:
/c =
0.329 Ex 2.5
(S/df
6.6.3.4 For individual members of spaced columns,
Sid ratio shall not exceed 80.
6.6.4 Compression members shall not be notched.
When it is necessary to pass services through such a
member, this shall be effected by means of a bored
hole provided that the local stress is calculated and
found to be within the permissible stress specified. The
distance from the edge of the hole to the edge of the
member shall not be less than one quarter of width of
the face.
6.7 Structural Members Subject to Bending and
Axial Stresses
6.7.1 Structural members subjected both to bending
and axial compression shall be designed to comply with
the following formula:
Jab
'A
is not greater than 1.
6.7.2 Structural members subjected both to bending
and axial tension shall be designed to comply with the
following formula:
/a
Jab
+ ^^- is not greater than 1 .
/t A
7 DESIGN OF COMMON STEEL WIRE NAIL
JOINTS
7.1 General
Nail jointed timber construction is suitable for light
and medium timber framings (trusses, etc) up to 15 m
spans. With the facilities of readily available materials
and simpler workmansjfip in mono-chord and split
chord constructions, this type of fabrication has a large
scope.
7.2 Dimensions of Members
7.2.1 The dimension of an individual piece of timber
(that is, any single member) shall be within the range
given below:
a) The minimum thickness of the main members
in mono-chord construction shall be 30 mm.
b) The minimum thickness of an individual piece
of members in split-chord construction shall
26
NATIONAL BUILDING CODE OF INDIA
be 20 mm for web members and 25 mm for
chord members,
c) The space between two adjacent pieces of
timber shall be restricted to a maximum of
3 times the thickness of the individual piece
of timber of the chord member. In case of web
members, it may be greater for joining
facilities.
7.3 No lengthening joint shall preferably be located
at a panel point. Generally not more than two, but
preferably one, lengthening joint shall be permitted
between the two panel points of the members.
7.4 Specification and Diameter of Nails
7.4.1 The nails used for timber joints shall conform
to Part 5 'Building Materials'. The nails shall be
diamond pointed.
7.4.2 The diameter of nail shall be within the limits of
one-eleventh to one-sixth of the least thickness of
members being connected.
7.4.3 Where the nails are exposed to be saline
conditions, common wire nails shall be galvanized.
7.5 Arrangement of Nails in the Joints
The end distances, edge distances and spacings of nails
in a nailed joint should be such as to avoid undue
splitting of the wood and shall not be less than those
given in 7.5.1 and 7.5.2.
7.5.1 Lenthening Joints
The requirement of spacing of nails in a lengthening
joint shall be as follows {see also Fig. 2):
SI Spacing of Nails
No.
Type of Requirement,
Stress in the Min
Joint
(1) (2)
(3) (4)
i) End distance
Tension 12 n
ii) In direction of
Compression 10 n
Tension 10 n
grain
iii) Edge distance
iv) Between row of
Compression 5 n
— 5n
— 5n
nails perpendicular
to the grain
NOTES
1 n is shank diameter of nails.
2 The 5 n distance between rows perpendicular to the grain
may be increased subject to the availability of width of the
member keeping edge distance constant.
7.5.2 Node Joints
The requirement for spacing of nails in node joints
shall be as specified in Fig. 3 where the members are
at right angle and as in Fig. 4 where the members are
inclined to one another at angles other than 90° and
subjected to either pure compression or pure tension.
7.6 Penetration of Nails
7.6.1 For a lap joint when the nails are driven from
the side of the thinner member, the length of penetration
of nails in the thicker member shall be one and a half
times the thickness of the thinner member subject to
maximum of the thickness of the thicker member.
7.6.2 For butt joints the nails shall be driven through
the entire thickness of the joint.
7.7 Design Considerations
7.7.1 Where a number of nails are used in a joint,
the allowable load in lateral resistance shall be the
sum of the allowable loads for the individual nails,
provided that the centroid of the group of these nails
lies on the axis of the member and the spacings
conform to 7.5. Where a large number of nails are to
be provided at a joint, they should be so arranged
that there are more of rows rather than more number
of nails in a row.
7.7.2 Nails shall, as far as practicable, be arranged so
that the line of force in a member passes through the
centroid of the group of nails. Where this is not
practicable, allowance shall be made for any
eccentricity in computing the maximum load on the
fixing nails as well as the loads and bending moment
in the member.
7.7.3 Adjacent nails shall preferably be driven from
opposite faces, that is, the nails are driven alternatively
from either face of joint.
7.7.4 For a rigid joint, a minimum of 2 nails for nodal
joints and 4 nails for lengthening joint shall be
driven.
7.7.5 Two nails in a horizontal row are better than
using the same number of nails in a vertical row.
7.8 Special Consideration in Nail- Jointed Truss
Construction
7.8. 1 The initial upward camber provided at the centre
of the lower chord of nail-jointed timber trusses shall
be not less than 1/200 of the effective span for timber
structures using seasoned wood and 1/100 for
unseasoned or partially seasoned wood.
7.8.2 The total combined thickness of the gusset or
splice plates on either side of the joint in a mono-chord
type construction shall not be less than one and a half
times the thickness of the main members subject to a
minimum thickness of 25 mm of individual gusset
plate.
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
27
EFFECTIVE END
DISTANCE, 1 0n min — -
5n A /r 10n >r-5n
, /t\A A ,
-10n
0000
5n
5n
5h
4
5n
I I I I
tiii
i i i i
i i i i
i i i I
i i i
12nmin ■*
2A MONOCHORD TYPE BUTT JOINT SUBJECT TO COMPRESSION
10n ~A /"\ 12n yr-10n
0-
0"
12nmin
5nmin
4
Snmin
5n mm
-4
t^
-EFFECTIVE END
DISTANCE, 5n min
, — I — I — I —
-J — I — I — ,
I I
I
n = SHANK DIAMETER OF NAIL
2B MONOCHORD TYPE BUTT JOINT SUBJECT TO TENSION
Fig. 2 Spacing of Nails in a Lenghthening Joint — Continued
28
NATIONAL BUILDING CODE OF INDIA
€
€
4-U-
3
EFFECTIVE END
DISTANCE, 10nmin
5n — IK /r-10n ^r- 5n
0000
0000
-10n min
5nmln
4
5nmin
5nmin
■4
5nmln
5nmin
n
EFFECTIVE END
DISTANCE, 5n min
2C SPLIT - CHORD TYPE BUTT JOINT SUBJECT TO COMPRESSION
€
€
12n min
4=t=t
t=t=t
10n min
12nmin
-lOn min
O
0-
0-
n * SHANK DIAMETER OF NAIL
2D SPLIT - CHORD TYPE BUTT JOINT SUBJECT TO TENSION
3
3
EFFECTIVE END
, DISTANCE. 12n min
5n min.
4,
Snmin
5n min.
+ ,
5n min.
EFFECTIVE END
DISTANCE, 5n min
Fig. 2 Spacing of Nails in a Lenghthening Joint
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
29
UNLOADED
EDGE
5n min
LOADED
EDGE
5n min
3A
c
z
3
3
**&
O o
-5n min
T
10n
-it
In
10n
n = SHANK DIAMETER OF NAIL
*5n MAY BE INCREASED TO 10n, IF THE DESIGNED WIDTH OF
CORD MEMBER PERMITS. OTHERWISE THE END OF THE LOADED
WEB MEMBER MAY BE EXTENDED BY 5n mln
3C
Fig. 3 Spacing of Nails where Members are at
Right Angles to One Another
30
NATIONAL BUILDING CODE OF INDIA
l^fe^d I
UNLOADED
EDGE
LOADED
EDGE
tfcfa&a i
LOADED
EDGE
UNLOADED
EDGE
TIMBER FISH
PLATE
BOTTOM
CHORD
\-M-''-^
5n
5n
5n
4C
*5n MAY BE INCREASED TO 10n, IF THE DESIGNED WIDTH OF CHORD MEMBER PERMITS.
OTHERWISE THE END OF THE LOADED WEB MEMBER MAY BE EXTENDED BY 5n mln
n * SHANK DIAMETER OF NAIL
Fig. 4 Spacing of Nails at Node Joints where Members are
Inclined to One Another
PART 6 STRUCTURAL DESIGN— SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
31
NOTES
1 The allowable load or lateral strength values of nails shall be
those as given in Table 13.
2 The strength data for joints given in the section apply to gusset
or splice or fish plates of solid wood; however, materials other
than solid wood may be used for gusset when field tests are
made and their strength requirements have been established.
7.8.3 The total combined thickness of all spacer blocks
or plates or both including outer splice plates, at any
joint in a split-chord type construction shall not be less
than one and a half times the total thickness of all the
main members at that joint.
7.9 Fabrication
The fabrication of nail-jointed timber construction shall
be done in accordance with good practice [6-3 A(7)].
8 DESIGN OF NAIL LAMINATED TIMBER
BEAMS
8.1 Method of Arrangement
8.1 .1 The beam is made up of 20 mm to 30 mm thick
planks placed vertically with joints staggered in the
adjoining planks with a minimum distance of 300 mm.
The planks are laminated with the help of wire nails at
regular intervals to take up horizontal shear developed
in the beam besides keeping the planks in position
(see Fig. 5).
8.1.2 The advantage in laminations lies in dimensional
stability, dispersal of defects and better structural
performance.
8.2 Sizes of Planks and Beams
8.2.1 The plank thickness for fabrication of nailed
laminated beams recommended are 20, 25 and 30 mm.
8.2.2 In case of nailed laminated timber beam the
maximum depth and length of planks shall be limited
to 250 mm and 2 000 mm, respectively.
8.2.3 In order to obtain the overall width of the beam,
the number and thickness of planks to form vertical
nailed laminated beams, and also type and size of wire
nail shall be as mentioned in Table 14. The protruding
portion of the nail shall be cut off or clenched across
the grains.
83 Design Considerations
8.3.1 Nail laminated beams shall be designed in
accordance with 6.
8.3.1.1 The deflection in the case of nailed laminated
timber beams, joists, purlins, battens and other tlexural
members supporting brittle materials like gypsum,
ceiling slates, tiles and asbestos sheets shall not exceed
1/480 of the span. The deflection in case of other
tlexural members shall not exceed 1/360 of the span
in the case of beams and joists, and 1/225 of the freely
hanging length in case of cantilevers.
8.3.2 Permissible lateral strength of mild steel wire
nails shall be as given in Table 2 and Table 3 for Indian
Species of timber, which shall apply to nails that have
their points cut flush with the faces. For nails clenched
across the grains the strength may be increased by 20
percent over the values for nails with points cut flush.
8.3.3 Arrangement of Nails
8.3.3.1 A minimum number of four nails in a vertical
row at regular interval not exceeding 75 mm to take
up horizontal shear as well as to keep the planks in
position shall be used. Near the joints of the planks
this distance may, however, be limited to 5 cm instead
of 75 mm.
Table 14 Number and Size of Planks and Nails for Nailed Laminated Beams
(Clause 8.2.3)
SI
Overall Width of Beam
No, of Planks
Thickness of Each Plank
Type and Size of Nail to be Used
No.
mm
mm
mm
(1)
(2)
(3)
(4)
(5)
i)
50
2
25
80 long 3.55 dia
ii)
60
3
20
-do-
iii)
70
3
(2 x 25)
(1 x 20)
-do-
iv)
80
4
20
100 long 4.0 dia
v)
90
3
30
-do-
vi)
100
4
25
125 long 5.0 dia
vii)
110
4
(3 x 30)
(1 x20)
= do =
viii)
120
4
30
-do-
ix)
150
5
30
150 long 5.0 dia
NOTE
— A number of combinations of the different thickness of planks may
be
adopted
as long as
the minimum and maximum
thickness of the planks are adhered to.
32
NATIONAL BUILDING CODE OF INDIA
H
H
W
CI
r
en
n
H
s
z
>
w
w
o
p
>
4000
1600
1600
800
1200
1600
1200
800
1600
1600
1
400
1600
1600
400
4=
I— S; :
-1
I
25-,
175
25— »
4@75mm = 300mm
_25 mm THICK TIMBER PLANKS
■50
■25 CAMBER
All dimensions in millimetres.
Fig. 5 Plan and Elevation of a Typical Nailed Laminated Timber Beam
8.3.3.2 Shear shall be calculated at various points of
the beam and the number of nails required shall be
accommodated within the distance equal to the depth
of the beam, with a minimum of 4 nails in a row at a
standard spacing as shown in Fig. 6.
1
8
o
— —
+
+
+ ^
o
cm!
•f
+
+ V
o:
CM
1 °
1 C\f
+
+
+
+
+
:
i
50
75
mm
75
-J
6A FOR 3.55 mm AND 4 mm DIAMETER NAILS
50
75
75
6B FOR 5 mm DIAMETER NAILS
All dimensions in millimetres.
Fig. 6 Standard Lengthwise Spacing in
Nailed Laminated Beam
8.3.3.3 If the depth of the beam is more, then the
vertical intermediate spacing of nails may be increased
proportionately.
8.3.3.4 If the nails required at a point are more than
that can be accommodated in a row, then these shall
be provided lengthwise of the beam within the distance
equal to the depth of the beam at standard lengthwise
spacing.
8.3.3.5 For nailed laminated beam minimum depth
of 100 mm for 3.55 mm and 4 mm diameter nails,
and 1 25 mm for 5 mm diameter nails shall be provided.
8.4 Fabrication
8.4.1 The fabrication of nailed laminated timber beams
shall be done in accordance with good practice
[6-3A(8)].
9 DESIGN OF BOLTED CONSTRUCTION
JOINTS
9.1 General
Bolted joints suit the requirements of prefabrication
in small and medium span timber structures for speed
and economy in construction. Bolt jointed construction
units offer better facilities as regards to workshop ease,
mass production of components, transport convenience
and re-assembly at site of work particularly in defence
sector for high altitudes and far off situations.
Designing is mainly influenced by the species, size of
bolts, moisture conditions and the inclination of
loadings to the grains. In principle bolted joints follow
the pattern of ri vetted joints in steel structures.
9.2 Design Considerations
9.2.1 Bolted timber construction shall be designed in
accordance with 6. The concept of critical section, that
is, the net section obtained by deducting the projected
area of bolt-holes from the cross-sectional area of
member is very important for the successful design
and economy in timber.
9.2.2 Bolt Bearing Strength of Wood
The allowable load for a bolt in a joint consisting of
two members (single shear) shall be taken as one half
the allowable loads calculated for a three member joint
(double shear) for the same t '/d 3 ratio. The percentage
of safe working compressive stress of timber on bolted
joints for different t'ld^ ratios shall be as given in
Table 15.
Table 15 Percentage of Safe Working
Compressive Stress of Timber for Bolted
Joints in Double Shear
(Clause 9.2.2)
t'ldz Ratio
Stress Percentage
__j^__
y"
^*
Parallel to Grain
Perpendicular to Grain
h
A 2
(1)
(2)
(3)
1.0
100
100
1.5
100
96
2.0
100
88
2.5
100
80
3.0
100
72
3.5
100
66
4.0
96
60
4.5
90
56
5.0
80
52
5.5
72
49
6.0
65
46
6.5
58
43
7.0
52
40
7.5
46
39
8.0
40
38
8.5
36
36
9.0
34
34
9.5
32
33
10.0
30
31
10.5
—
31
11.0
—
30
11.5
—
30
12.0
_
28
34
NATIONAL BUILDING CODE OF INDIA
9.2.2.1 Where a number of bolts are used in a joint,
the allowable loads shall be the sum of the allowable
loads for the individual bolts.
9.2.2.2 The factors for different bolt diameter used in
calculating safe bearing stress perpendicular to grain
in the joint shall be as given in Table 16.
b)
Spacing Between Rows of Bolts
1) For perpendicular to grain loading —
Table
16 Bolt Diameter Factor
(Clause 9.2.2.2)
SI No.
Diameter of Bolt
Diameter
mm
Factor (d r )
(1)
(2) \
(3)
i)
6
5.70
ii)
10
3.60
iii)
12
3.35
iv)
16
3.15
v)
20
3.05
vi)
22
3.00
vii)
25
2.90
9.2.3 Dimensions of Members
a) The minimum thickness of the main member
in mono-chord construction shall be 40 mm.
b) The minimum thickness of side members shall
be 20 mm and shall be half the thickness of
main members.
c) The minimum individual thickness of spaced
member in split-chord construction shall be
20 mm and 25 mm for webs and chord
members respectively.
9.2.4 Bolts and Bolting
a) The diameter of bolt in the main member shall
be so chosen to give larger slenderness (t'ld 3 )
ratio of bolt.
b) There shall be more number of small diameter
bolts rather than small number of large
diameter bolts in a joint.
c) A minimum of two bolts for nodal joints and
four bolts for lengthening joints shall be
provided.
d) There shall be more number of rows rather
than more bolts in a row.
e) The bolt holes shall be of such diameter that
the bolt can be driven easily.
f) Washers shall be used between the head of
bolt and wood surface as also between the nut
and wood.
9.3 Arrangement of Bolts
9.3.1 The following spacings in bolted joints shall be
followed (see Fig. 7):
a) Spacing of Bolts in a Row — For parallel and
perpendicular to grain loading = 4 d 3
2.5 d 3 to 5 d 3 (2.5 d,
for t'/d 3 ratio of 2
2)
c)
d)
and 5 d 3 for tld 3 ratio of 6 or more. For
ratios between 2 to 6 the spacing shall be
obtained by interpolation.
For parallel to grain loading — At least
(N-A) d 3 with a minimum of 2.5 d y Also
governed by net area at critical section
which should be 80 percent of the total
area in bearing under all bolts.
End Distance — ld 3 for soft woods in tension,
5 d 3 for hardwoods in tension and 4 d 3 for all
species in compression.
Edge Distance
1 ) For parallel to grain loading 1 .5 d 3 or half
the distance between rows of bolts,
whichever is greater.
For perpendicular to grain loading,
(loaded edge distance) shall be at least
4 A.
2)
9.3.2 For inclined members, the spacing given above
for perpendicular and parallel to grain of wood may
be used as a guide and bolts arranged at the joint with
respect to loading direction.
9.3.3 The bolts shall be arranged in such a manner so
as to pass the centre of resistance of bolts through the
inter-section of the gravity axis of the members.
9.3.4 Staggering of bolts shall be avoided as far as
possible in case of members loaded parallel to grain
of wood. For loads acting perpendicular to grain of
wood, staggering is preferable to avoid splitting due
to weather effects,
9.3.5 Bolting
The bolt holes shall be bored or drilled perpendicular
to the surface involved. Forcible driving of the bolts
shall be avoided which may cause cracking or splitting
of members. A bolt hole of 1.0 mm oversize may be
used as a guide for preboring.
9.3.5.1 Bolts shall be tightened after one year of
completion of structure and subsequently at an interval
of two to three years.
9.4 Outline for Design of Bolted Joints
Allowable load on one bolt (unit bearing stress) in a
joint with wooden splice plates shall not be greater
than value of P, R, F as determined by one of the
following equations:
a) For Loads Parallel to Grain
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
35
-I
-I
fdUETyrtn
■fa— I l ii — -L»
TT
4U-
IT
tf
l'l
■4U-
r*n
i — r
irrngTurtn,
i — r
■i i'i Hi
tip tip
■4d 3
-=^zr
<^v
4d a
/rpyr fn
rr**7r
ti — m-
i>i ill
■ H I i i Mi i '
rrtTurfn.
TI
4H-
TIT
j
4tf-
7A SPACING OF BOLTS IN LENTHENING JOINTS
(JOINTS LOADED PARALLEL TO GRAIN)
HEAD
HEXAGONAL
j-
WASHER
j-
rv^rs/^
2d »min.
v-
4d 3
40*
1,5d 3 mln-
o
I
UNLOADED
EDGE,
r
LOADED
EDGE
- 1 .5d3min
2.5d 3 fort/d3RATI0 2
5d 3 fort/d 3 RATI06
^LOADED 1
4d 3
t
i.
2d 3 min.
1.5d 3 min-
$
o o
r
UNLOADED
EDGE
-1.5d 3 mln
-2.5d 3 ttor(/d3RATI0 2
5d 3 ft)rtftl3RATI0 6
7B SPACING OF BOLTS AT NODE JOINTS
Fig. 7 Typical Spacing of Bolts in Structural Joints
36
NATIONAL BUILDING CODE OF INDIA
b) For Loads Perpendicular to Grain
R = fen a\dn
c) For Loads at an Angle to Grain
PR
F =
9.5 Fabrication
P sin 2 9 + R cos 2
The fabrication of bolt jointed construction shall be in
accordance with good practice [6-3 A(9)].
10 DESIGN OF TIMBER CONNECTOR JOINTS
10.1 In large span structures, the members have to
transmit very heavy stresses requiring stronger jointing
techniques with metallic rings or wooden disc-dowels.
Improvized metallic ring connector is a split circular
band of steel made from mild steel pipes. This is placed
in the grooves cut into the contact faces of the timber
members to be joined, the assembly being held together
by means of a connecting bolt.
10.1.1 Dimensions of Members
Variation of thickness of central (main) and side
members affect the load carrying capacity of the joint.
The thickness of main member shall be at least 51 mm
and that of side member 38 mm with length and width
of members governed by placement of connector at
joint.
The metallic connector shall be so placed that the
loaded edge distance is not less than the diameter of
the connector and the end distance not less than 1.75
times the diameter on the loaded side.
10.1.2 Design Considerations
Figure 8 illustrates the primary stresses in a split ring
connector joint under tension. The shaded areas
represent the part of wood in shear, compression and
tension. Related formulae for the same are indicated
in Fig. 8.
For fabrication of structural members, a hole of the
required size of the bolt is drilled into the member and
a groove is made on the contact faces of the joint.
Theoretical safe loads in design shall be corroborated
with sample tests done in accordance with good
practice [6-3(10)].
NOTE — A pilot study on determination of strength of ring
connector joint in a compression test for a specific design
problem yielded the data as given below:
Strength of Improvized Split Ring Connectors in Mesua (Mesuaferra) (Pilot Study)
No. and
No. and Size
Side
Central
Load
End
Inter-
Load per
Diameter
of Bolt used in
Member
Member
Direction
Distance
mediate
Pair
(
/Ring
a
Joint
w.r.t.
Distance
of
used in a
Grains of
Connector
Joint
Wood
>-
-\
y^
■~\
r
"S
/-
A
/~
A
No.
Size
No.
Size
Thick-
ness
Width
Thick-
ness
Width
mm
mm
kgf
mm
mm
mm
mm
mm
mm
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
2
63
12 x 125
31
92
38
92
Parallel
63
—
3 930
2
63
12 x 125
31
92
38
92
Parallel
75
—
4 185
2
63
12x150
38
92
63
92
Parallel
75
—
4010
2
63
12x150
38
117
63
117
Parallel
75
—
4 450
2
63
12 x 125
31
138
38
92
Perpendicular
69
—
2 520
2
63
12 x 125
38
138
38
92
Perpendicular
69
—
3515
2
100
19 x 175
38
138
66
138
Parallel
100
—
7 075
2
100
19 x 175
38
138
66
138
Parallel
125
—
7 370
2
100
19x175
41
138
75
138
Parallel
100
—
7 220
2
100
19x175
41
138
75
138
Parallel
125
—
7 645
4
100
2
19x200
38
138
66
138
Parallel
100
150
5 655
4
100
2
19x200
41
138
75
138
Parallel
100
150
5 925
4
100
2
19 x 200
41
138
75
138
Parallel
125
200
7 135
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
37
SPLIT RING CONNECTOR
a/2
ti-a
w
a/2
Fig. 8 Stress Distribution in a Split Ring Connector
1 0.2 Wooden Disc-Dowel
10.2.1 It is a circular hardwood disc generally tapered
each way from the middle so as to form a double
conical frustum. Such a disc is made to fit into
preformed holes (recesses), half in one member and
the other half in another, the assembly being held by
one mild steel bolt through the centre of the disc to act
as a coupling for keeping the jointed wooden members
from spreading apart.
10.2.2 Dimensions of Members
The thickness of dowel may vary from 25 mm to
35 mm and diameter from 50 mm to 150 mm. The
diameter of dowel shall be 3.25 to 3.50 times the
thickness.
The edge clearance shall range from 12 mm to 20 mm
as per the size of the dowel. The end clearance shall be
at least equal to the diameter of dowel for joints
subjected to tension and three-fourth the diameter for
compression joints. Disc-dowel shall be turned from
quarter sawn planks of seasoned material.
10.2.3 Choice of Species
Wood used for making dowels shall be fairly straight
grained, free from excessive liability to shrink and
warp, and retain shape well after seasoning species
recommended include:
Babul
Dhaman
Irul
38
NATIONAL BUILDING CODE OF INDIA
Sissoo
Rose wood
Sandal
Axle-wood
Padauk
Pyinkado
Yon
NOTE — Data on the above species as per Table 1 except
for the species Pyinkado, which is not an indigenous species.
10.2.4 Design Considerations
Figure 9 illustrates the forces on dowel in a lap joint
and butt joint. Dowel is subjected to shearing at the
mid- section, and compression along the grain at the
bearing surfaces. For equal strength in both the forces,
formula equations are given in Fig. 9 to determine the
size of dowel.
The making of wooden discs may present some
problems in the field, but they may be made in small
LAP JOINT
-zzBzzz*
-S-
HNSSSSSSH
tor
BUTT JOINT
Lap Joint: Bolt in simple tension due to clockwise turning moment on dowel-
Butt Joint; No tilting moment in dowel due to balancing effect [dowels are in shear (no bending, shearing
and tensile stress on bolts)]
Size of dowel for equal strength in both shearing and bearing.
K d 2 /4 X S = d X til X c
where
d = Mid diameter of the dowel,
t = Thickness of dowel,
s = Safe working stress in shear along grain, and
c = Safe compressive stress along grain.
NOTE — Symbols are exclusive to this figure.
Fig. 9 Distribution of Forces in Dowel Joint
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
39
workshop to the specifications of the designer. This is
also economically important. Once the wood fittings
are shop tailored and made, the construction process
in the field is greatly simplified.
Theoretical safe loads in design shall be confirmed
through sample tests.
NOTE — Some experimental studies have indicated the
following safe loads in kgf for dowels bearing parallel to the
grain.
*n
*n
»o
<n
^n
^n
<M
<N
<N
X
X
X
X
X
X
<3
<N
>o
(N
*n
ts.
o
<N
(1) (2) (3) (4) (5) (6) (7) (8)
Sal Babul 680 1 000 1 360 1 815 2 270 2 810
Sal Sissoo 545 770 1 045 1 360 1 725 2 130
11 GLUED LAMINATED CONSTRUCTION
AND FINGER JOINTS
11.1 Developments in the field of synthetic adhesive
have brought glueing techniques within the range of
engineering practice. Timber members of larger cross-
sections and long lengths can be fabricated from small
sized planks by the process of gluelam. The term glued
laminated timber construction as applied to structural
members refers to various laminations glued together,
either in straight or curved form, having grain of all
laminations essentially parallel to the lengths of the
member.
11.1.1 Choice of Glue
The adhesive used for glued laminated assembly are
'gap filling' type. A 'filler' in powder form is
introduced in the adhesive. Structural adhesives are
supplied either in powder form to which water is added
or in resin form to which a hardener or catalyst is added.
For choice of glues, reference may be made to good
practice [6-3 A(l 1)]. However, it is important that only
boiling water proof (BWP) grade adhesives shall be
used for fabrication of gluelam in tropical, high humid
climates like India.
11.1.2 Manufacturing Schedule
In absence of a systematic flow-line in a factory,
provisions of intermediate technology shall be created
for manufacturing structural elements. The schedule
involves steps:
a) Drying of planks;
b) Planning;
c) End-jointing by scarfs or fingers;
d) Machining of laminations;
e) Setting up dry assembly of structural unit;
f) Application of glue;
g) Assembly and pressing the laminations;
h) Curing the glue lines, as specified; and
j) Finishing, protection and storage.
11.2 Finger joints are glued joints connecting timber
members end-to-end (Fig. 10). Such joints shall be
produced by cutting profiles (tapered projections) in
the form of V-shaped grooves to the ends of timber
planks or scantling to be joined, glueing the interfaces
and then meeting the two ends together underpressure.
Finger joints provide long lengths of timber, ideal for
upgrading timber by permitting removal of defects,
minimizing warping and reducing wastage by avoiding
short off-cuts.
11.2.1 In finger joints the glued surfaces are on the
side grain rather than on the end grain and the glue
line is stressed in shear rather in tension.
11.2.1.1 The figures can be cut from edge-to-edge or
from face-to-face. The difference is mainly in
appearance, although bending strength increases if
several fingers share the load. Thus a joist is slightly
stronger with edge-to-edge finger joints and a plank is
stronger with face-to-face finger joint.
11.2.1.2 For structural finger jointed members for
interior dry locations, adhesives based on melamine
formaldehyde cross linked polyvinyl acetate (PVA) are
suited. For high humid and exterior conditions, phenol
formaldehyde and resorcinol formaldehyde type
adhesives are recommended. Proper adhesives should
be selected in consultation with the designer and
adhesive manufacturers and assessed in accordance
with accepted standard [6-3 A(l 1)].
11.2.2 Manufacturing Process
In the absence of sophisticated machinery, the finger
joints shall be manufactured through intermediate
technology with the following steps:
a) Drying of wood,
b) Removal of knots and other defects,
c) Squaring the ends of the laminating planks,
d) Cutting the profile of finger joint in the end
grain,
e) Applying adhesives on the finger interfaces,
f) Pressing the joint together at specified pressure,
g) Curing of adhesive line at specified
temperature, and
h) Planning of finger-jointed planks for smooth
surface.
11.2.3 Strength
Strength of finger joints depends upon the geometry
of the profile for structural purpose; this is generally
50 mm long, 12 mm pitch.
40
NATIONAL BUILDING CODE OF INDIA
Tx^r
ID
X3_
Z3D
TIP GAP
e
L = FINGER LENGTH
p = PITCH
t = TIP THICKNESS
8=6°
ORIENTATION OF FiNGER JOINTS
Fig, 10 Typical Finger Joint Geometry
11*2,3,1 End joints shall be scattered in adjacent
laminations, which shall not be located in very highly
stressed outer laminations.
11,2,4 Tip thickness will be as small as practically
possible.
12 LAMINATED VENEER LUMBER
12.1 Certain reconstituted lignocellulosic products
with fibre oriented along a specific direction have
been developed and are being adopted for load
bearing applications. Laminated veneer lumber is one
such product developed as a result of researches in
plantation grown species of wood. Density of
laminated veneer lumber ranges from 0.6 to 0.75
which is manufactured in accordance with good
practice [6-3A(12)].
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
41
12.1.1 Dimensions
Sizes of laminated veneer lumber composite shall be
inclusive of margin for dressing and finishing unless
manufactured to order. The margin for dressing and
finishing shall not exceed 3 mm in the width and
thickness and 12 mm in the length.
12.1.2 Permissible Defects
Jointing gaps — Not more than 3 mm wide,
provided they are well staggered in
their spacing and position between
the successive plies.
Slope of grain — Not exceeding 1 in 10 in the face
layers.
Tight knot — Three numbers up to 25 mm
diameter in one square metre
provided they are spaced 300 mm
or more apart.
Warp — Not exceeding 1.5 mm per metre
length.
12.1.3 Strength Requirements
The strength requirements for laminated veneer lumber
shall be as per Table 17.
13 DESIGN OF GLUED LAMINATED BEAMS
13.1 General
Glued laminated structural members shall be fabricated
only where there are adequate facilities for accurate
sizing and surfacing of planks, uniform application of
glue, prompt assembly, and application of adequate
pressure and prescribed temperature for setting and
curing of the glue. Design and fabrication shall be in
accordance with established engineering principles and
good practice. A glued laminated beam is a straight
member made from a number of laminations assembled
both ways either horizontally or vertically. While
vertical laminations have limitations in restricting
the cross-section of a beam by width of the plank,
horizontally laminated section offers wider scope to
the designer in creating even the curved members.
Simple straight beams and joists are used for many
structures from small domestic rafters or ridges to the
light industrial structures.
13.2 Design
The design of glue laminated wood elements shall be
in accordance with good engineering practice and shall
take into consideration the species and grade of timber
used, presence of defects, location of end joints in
laminations, depth of beams and moisture contents
expected while in service. Beams of large spans shall
be designed with a suitable camber to assist in
achieving the most cost effective section where
deflection governs the design. The strength and
stiffness of laminated beams is often governed by the
quality of outer laminations. Glued laminated beams
can be tapered to follow specific roof slopes across a
building and/or to commensurate with the varying
bending moments.
13.3 Material
Laminating boards shall not contain decay, knots or
other strength reducing characteristics in excess of
those sizes or amounts permitted by specifications. The
moisture content shall approach that expected in
service and shall in no case exceed 15 percent at the
time of glueing. The moisture content of individual
Table 17 Requirements of Laminated Veneer Lumber
(Clause 12.1.3)
SI No.
(1)
Properties
(2)
Requirement
(3)
i)
ii)
iii)
iv)
v)
vi)
vii)
viii)
Modulus of rupture (N/mm 2 ), Min
Modulus of elasticity (N/mm 2 ), Min
Compressive strength parallel to grain (N/mm 2 ), Min
Compressive strength perpendicular to grain:
a) Parallel to grain (N/mm 2 ), Min
b) Perpendicular to grain (N/mm 2 ), Min
Horizontal shear:
a) Parallel to laminae (N/mm 2 ), Min
b) Perpendicular to laminae (N/mm 2 ), Min
Tensile strength parallel to grain (N/mm 2 ), Min
Screw holding power:
a) Edge (N), Min
b) Face (N), Min
Thickness swelling in 2 h water soaking (percent), Max
50
7 500
35
35
50
55
2 300
2 700
3
42
NATIONAL BUILDING CODE OF INDIA
laminations in a structural member shall not differ by
more than 3 percent at the time of glueing. Glue shall
be of type suitable for the intended service of a
structural member.
13.4 Fabrication/Manufacture
In order to assure a well-bonded and well-finished
member of true shape and size, all equipments, end-
jointing, glue spread, assembly, pressing, curing or any
other operation in connection with the manufacture of
glued structural members shall be in accordance
with the available good practices and as per glue
manufacturers' instructions as applicable.
13.5 Testing
For examining the quality of glue and its relative
strength vis-a-vis species of timber in glued laminated
construction, it is necessary to conduct block shear and
other related tests in accordance with accepted standard
|6-3A(11)].
Structural loading tests on prototype sizes provide
information on the strength properties, stiffness or
rigidity against deflection of a beam.
14 STRUCTURAL USE OF PLYWOOD
Unlike sawn timber, plywood is a layered panel product
comprising veneers of wood bonded together with
adjacent layers usually at right angles. As wood is
strongest when stressed parallel to grain, and weak
perpendicular to grain, the lay up or arrangement of
veneers in the panel determines its properties. When
the face grain of the plywood is parallel to the direction
of stress, veneers parallel to the face grain carry almost
all the load. Some information/guidelines for structural
use of plywood which would be manufactured in
accordance with accepted standard [6-3A(13)] are
given in 14.1 to 14.3.
14.1 The plywood has a high strength to weight ratio,
and is dimensionally stable material available in sheets
of a number of thicknesses and construction. Plywood
can be sawn, drilled and nailed with ordinary wood
working tools. The glues used to bond these veneers
together are derived from synthetic resins which are
set and cured by heating. The properties of adhesives
can determine the durability of plywood.
14.2 In glued plywood construction, structural
plywood is glued to timber resulting in highly
efficient and light structural components like web
beams (I and box sections), (Fig. 11 and Fig. 12)
stressed skin panels (Fig. 13) used for flooring and
walling and pre-fabricated houses, cabins, etc.
Glueing can be carried out by nail glueing techniques
with special clamps. High shear strength of plywood
in combination with high flexural strength and
stiffness of wood result in structures characterized
by high stiffness for even medium spares. Plywood
can act as web transmitting shear stress in web bearing
or stressed skin or sandwich construction. The
effective moment of inertia of web beam and stressed
skin construction depends on modular ratio that is, E
of wood to E of plywood.
14.3 Structural plywood is also very efficient as
cladding material in wood frame construction, such as
houses. This type of sheathing is capable of resisting
racking due to wind and quack forces. Structural
plywood has been widely used as diaphragm
(horizontal) as in roofing and flooring in timber frame
construction. It has been established that 6 mm thick
plywood can be used for sheathing and even for web
and stressed skin construction, 9-12 mm thick plywood
is suitable for beams, flooring diaphragms, etc. Phenol
formaldehyde (PF) and PRF adhesive are suitable for
fabrication of glued plywood components. 6 mm-
12 mm thick structural plywood can be very well used
as nailed or bolded gussets in fixing members of trusses
or lattice griders or trussed rafters.
Normally, scarf joints are used for fixing plywood to
required length and timber can be joined by using either
finger or scarf joints. Arch panels, folded plates, shelves
are other possibilities with this technique.
15 TRUSSED RAFTER
15.1 General
A roof truss is essentially a plane structure which is
very stiff in the plane of the members, that is, the plane
in which it is expected to carry loads, but very flexible
in every other direction. Thus it can virtually be seen
as a deep, narrow girder liable to buckling and twisting
under loads. In order, therefore, to reduce this effect,
eccentricity of loading and promote prefabrication for
economy, low-pitched trussed rafters are designed with
bolt ply/nail ply joints. Plywood as gussets, besides
being simple have inherent constructional advantage
of grain over solid wood for joints, and a better balance
is achievable between the joint strength and the
member strength.
Trussed rafters are light weight truss units spaced at
close centres for limited spans to carry different types
of roof loads. They are made from timber members of
uniform thickness fastened together in one plane. The
plywood gussets may be nailed or glued to the timber
to form the joints. Conceptually a trussed rafter is a
triangular pin jointed system, traditionally meant to
carry the combined roof weight, cladding services and
wind loads. There is considerable scope for saving
timber by minimizing the sections through proper
design without affecting structural and functional
requirements.
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
43
WOODEN FLANGE
(TYPICAL),
^m
-PLYWOOD
WEB
I-SECTION
PLYWOOD
WEBS
PLYWOOD
DOUBLE-I
BOX
Fig. 1 1 Typical Cross-Section of Web Beams
-STIFFNER
3Z3
^
WOODEN
FLANGE
3
^?
-SPAN UPTO 6 - 9 m-
STRAIGHT
PLYWOOD-
CD □ □
CD D D
SECTION XX
-SPAN UPTO 9 m-
DOUBLE TAPERD
SPAN UPTO 9 m
HAUNCHED
Fig. 12 Web Beam Configurations
44
NATIONAL BUILDING CODE OF INDIA
UPPER SKIN
WEBS
LOWER SKIN
Fig. 13 Stressed Skin Panel Construction (Single Skin or Double Skin)
Trussed rafters require to be supported only at their
ends so that there is no need to provide load bearing
internal walls, Purlins, etc are dispensed with and in
comparison with traditional methods of construction
they use less timber and considerably reduces of site
labour, Mass production or reliable units can be carried
out under workshop controls.
15.2 Design
Trussed rafter shall be designed to sustain the dead
and imposed loads specified in Part 6 'Structural
Design: Section 1 Loads, Forces and Effects' and the
combinations expected to occur. Extra stresses/
deflections during handling, transportation and erection
shall be taken care of. Structural analysis, use of load-
slip and moment, rotation characteristics of the
individual joints may be used if feasible. Alternatively
the maximum direct force in a member may be assessed
to be given by an idealized pin-jointed framework, fully
loaded with maximum dead and imposed load in the
combination in which they may reasonably be expected
to occur.
15.3 Timber
The species of timber including plantation grown
species which can be used for trussed rafter
construction and permissible stresses thereof shall be
in accordance with Table 1. Moisture contents to be as
per zonal requirements in accordance with 4.4.
15.4 Plywood
Boiling water resistant (BWR) grade preservative
treated plywood shall be used in accordance with
accepted standard [6-3A(13)]. Introduction of a
plywood gusset simplifies the jointing and in addition
provides rigidity to the joint. Preservation of plywood
and other panel products shall be done in accordance
with good practice [6-3A(14)].
16 STRUCTURAL SANDWICHES
16.1 General
Sandwich constructions are composites of different
materials including wood based materials formed by
bonding two thin facings of high strength material to a
light weight core which provides a combination of
desirable properties that are not attainable with the
individual constituent materials (Fig. 14). The thin
facings are usually of strong dense material since that
are the principal load carrying members of the
construction. The core must be stiff enough to ensure
the faces remain at the correct distance apart. The
sandwiches used as structural elements in building
construction shall be adequately designed for their
intended services and shall be fabricated only where
there are adequate facilities for glueing or otherwise
bonding cores to facings to ensure a strong and durable
product. The entire assembly provides a structural
element of high strength and stiffness in proportion to
its mass.
Non-structural advantages can also be derived by proper
selection of facing and core material for example, an
impermeable facings can be used to serve as a moisture
barrier for walls and roof panels and core may also be
selected to provide thermal and/or acoustic insulation,
fire resistance, etc, besides the dimensional stability.
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
45
ADHESIVE
-FACE SHEETS
Fig. 14 Standwich Construction in Structural Applications
16.2 Cores
Sandwich cores shall be of such characteristics as to
give to the required lateral support to the stressed
facings to sustain or transmit the assumed loads or
stresses. Core generally carries shearing loads and to
support the thin facings due to compressive loads. Core
shall maintain the strength and durability under
the conditions of service for which their use is
recommended. A material with low E and small shear
modulus may be suitable.
16.3 Facings
Facings shall have sufficient strength and rigidity to
resist stresses that may come upon them when
fabricated into a sandwich construction. They shall be
thick enough to carry compressive and tensile stresses
and to resist puncture or denting that may be expected
in normal usages.
16.4 Designing
Structural designing may be comparable to the design
of I-beams, the facings of the sandwich represent the
flanges of the I-beam and the sandwich core I-beam
web.
16.5 Tests
Panels of sandwich construction shall be subject to
testing in accordance with accepted standards
[6-3A(15)]. Tests shall include, as applicable, one or
more of the following:
a) Flexural strength/stiffness,
b) Edge-wise compressions,
c) Flat-wise compression,
d) Shear in flat-wise plane,
e) Rat-wise tensions,
f) Flexural creep (creep behaviour of adhesive),
g) Cantilever vibrations (dynamic property), and
h) Weathering for dimensional stability.
17 LAMELLA ROOFING
17.1 General
The Lamella roofing offers an excellent architectural
edifice in timber, amenable to prefabrication, light
weight structure with high central clearance. It is
essentially an arched structure formed by a system of
intersecting skewed arches built-up of relatively short
timber planks of uniform length and cross-section.
Roof is designed as a two hinged arch with a depth
equal to the depth of an individual lamella and width
equal to the span of the building. The curved lamellas
(planks) are bevelled and bored at the ends and bolted
together at an angle, forming a network (grid) pattern
of mutually braced and stiffened members (Fig. 15).
The design shall be based on the balanced or
unbalanced assumed load distribution used for roof
arches. Effect of deformation or slip of joints under
load on the induced stresses shall be considered in
design. Thrust components in both transverse and
46
NATIONAL BUILDING CODE OF INDIA
-WIND BLOCK
LAMELLA
LJV-1
-BRESSUMMER
LAMELLA GRID
LAMELLA GRID
MIDDLE LAMELLA
cOUTER LAMELLA
38° TO 42
BOLT
LAMELLA NODAL JOINT
LOAD REACTION DIAGRAM
Fig. 15 Typical Arrangement of Lamella Roofing
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
47
longitudinal directions of the building due to skewness
of the lamella arch shall be adequately resisted. Thrust
at lamella joints shall be resisted by the moment of
inertia in the continuous lamella and roof sheathening
(decking) of lamella roofing. The interaction of arches
in two directions adds to the strength and stability
against horizontal forces. For design calculations
several assumption tested and observed derivations,
long-duration loading factors, seasoning advantages
and effects of defects are taken into account.
17.2 Lamellas
Planking shall be of a grade of timber that is adequate
in strength and stiffness to sustain the assumed loads,
forces, thrust and bending moments generated in
Lamella roofing. Lamella planks shall be seasoned to
a moisture content approximating that they will attain
in service. Lamella joints shall be proportioned so that
allowable stresses at bearings of the non-continuous
lamellas on the continuous lamellas or bearings under
the head or washer of bolts are not exceeded.
17.3 Construction
Design and construction of lamella roofs in India
assumes the roof surfaces to be cylindrical with every
individual lamella an elliptic segment of an elliptical
arch of constant curved length but of different
curvature. Lamella construction is thus more of an art
than science as there is no analytical method available
for true generation of schedule of cutting lengths and
curvature of curved members forming the lamella grid.
Dependence of an engineer on the practical ingenuity
of master carpenter is almost final. All the lamella joints
shall be accurately cut and fitted to give full bearing
without excessive deformation or slip. Bolts at lamella
splices shall be adequate to hold the members in their
proper position and shall not be over tightened to cause
bending of the lamellas or mashing of wood under the
bolt heads. Connection of lamellas to the end arches
shall be adequate to transmit the thrust or any other
force. Sufficient false work or sliding jig shall be
provided for the support of lamella roof during actual
construction/erection.
18 NAIL AND SCREW HOLDING POWER OF
TIMBER
18.1 General
One of the most common ways of joining timber pieces
to one another is by means of common wire nails and
wood screws. Timber is used for structural and non-
structural purposes in form of scantlings, rafters, joists,
boarding, crating and packing cases, etc needing
suitable methods of joining them. Nevertheless it is
the timber which holds the nails or screws and as such
pulling of the nails/screws is the chief factor which
come into play predominantly. In structural nailed
joints, nails are essentially loaded laterally, the design
data for which is already available as standard code of
practice. Data on holding power of nails/screws in
different species is also useful for common commercial
purposes. The resistance of mechanical fastenings is a
function of the specific gravity of wood, direction of
penetration with respect to the grain direction, depth
of penetration and the diameter of fastener assuming
that the spacing of fasteners should be adequate to
preclude splitting of wood.
18.2 Nails
Nails are probably the most common and familiar
fastener. They are of many types and sizes in
accordance with the accepted standards [6-3A(16)].
In general nails give stronger joints when driven into
the side grain of wood than into the end grain. Nails
perform best when loaded laterally as compared to axial
withdrawal so the nailed joints should be designed for
lateral nail bearing in structural design. Information
on withdrawal resistance of nails is available and joints
may be designed for that kind of loading as and when
necessary.
18.3 Screw
Next to the hammer driven nails, the wood screw may
be the most commonly used fastener. Wood screws
are seldom used in structural work because of their
primary advantage is in withdrawal resistance, for
example, for fixing of ceiling boards to joists, purlin
cleats, besides the door hinges etc. They are of
considerable structural importance in fixture design and
manufacture. Wood screws are generally finished in a
variety of head shapes and manufactured in various
lengths for different screw diameters or gauges in
accordance with the accepted standard [6-3A(17)].
The withdrawal resistance of wood screws is a function
of screw diameter, length of engagement of the
threaded portion into the member, and the specific
gravity of the species of wood. Withdrawal load
capacity of wood screws are available for some species
and joints may be designed accordingly. End grain load
on wood screws are unreliable and wood screws shall
not be used for that purpose.
19 PROTECTION AGAINST TERMITE ATTACK
IN BUILDINGS
19.1 Two groups of organisms which affect the
mechanical and aesthetic properties of wood in houses
are fungi and insects. The most important wood
destroying insects belong to termites and beetles. Of
about 250 species of wood destroying termites recorded
in India, not more than a dozen species attack building
causing about 90 percent of the damage to timber and
48
NATIONAL BUILDING CODE OF INDIA
other cellulosic materials. Subterranean termites are
the most destructive of the insects that infest wood
in houses justifying prevention measures to be
incorporated in the design and construction of
buildings.
19.1.1 Control measures consist in isolating or sealing
off the building from termites by chemical and non-
chemical construction techniques. It is recognized that
95 percent damage is due to internal travel of the
termites from ground upwards rather than external
entry through entrance thus calling upon for
appropriate control measures in accordance with good
practices [6-3A(18)].
19.2 Chemical Methods
Termites live in soil in large colonies and damage the
wooden structure in the buildings by eating up the wood
or building nests in the wood. Poisoning the soil under
and around the building is a normal recommended
practice. Spraying of chemical solution in the trenches
of foundations in and around walls, areas under floors
before and after filling of earth, etc. In already
constructed building the treatment can be given by
digging trenches all around the building and then giving
a liberal dose of chemicals and then closing the trenches.
19.3 Wood Preservatives
Natural resistance against organisms of quite a few
wood species provides durability of timber without
special protection measure. It is a property of
heartwood while sapwood is normally always
susceptible to attack by organisms. Preservatives
should be well applied with sufficient penetration into
timber. For engineers, architects and builders, the
following are prime considerations for choice of
preservatives:
a)
b)
c)
d)
e)
f)
g)
Inflammability of treated timber is not
increased and mechanical properties are not
decreased;
Compatibility with the glue in laminated
wood, plywood and board material;
Water repellent effect is preferred;
Possible suitability for priming coat;
Possibility of painting and other finishes;
Non-corrosive nature in case of metal
fasteners; and
Influence on plastics, rubber, tiles and
concrete.
19.4 Constructional Method
Protection against potential problem of termite attack
can simply be carried out by ordinary good construction
which prevents a colony from gaining access by:
a) periodic visual observations on termite
galleries to be broken off;
b) specially formed and properly installed metal
shield at plinth level; and
c) continuous floor slabs, apron floors and
termite grooves on periphery of buildings.
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and 'accepted standards'
in the fulfilment of the requirements of the Code. The
latest version of a standard shall be adopted at the time
of the enforcement of the Code. The standards
listed may be used by the Authority as a guide in
conformance with the requirements of the referred
clauses in the Code.
IS No. Title
(1) 707 : 1976 Glossary of terms applicable
to timber technology and
utilization (second revision)
(2) 1708 Methods of testing small
(Parts 1 to 18) : 1986 clear specimens of timber
(second revision)
2408 : 1963 Methods of static tests of
timbers in structural sizes
2455 : 1990 Methods of sampling of
model trees and logs for
IS No.
(3) 4970 : 1973
(4) 287 : 1993
(5) 3629 : 1986
(6) 401 : 2001
(7) 2366 : 1983
Title
timber testing and their
conversion (second revision)
Key for identification of
commercial timbers (first
revision)
Recommendations for
maximum permissible
moisture content of timber
used for different purposes
(third revision)
Specification for structural
timber in building (first
revision)
Code of practice for
preservation of timber
(fourth revision)
Code of practice for nail-
jointed timber construction
(first revision)
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3A TIMBER
49
IS No.
(8) 4983 : 1968
(9) 11096: 1984
(10)4907: 1968
(11)9188: 1979
(12) 14616: 1999
(13) 10701 : 1983
4990 : 1993
(14)12120: 1987
(15)9307
Title
Code of practice for design
and construction of nail
laminated timber beam (first
revision)
Code of practice for design
construction of bolt-jointed
construction
Methods of testing timber
connectors
Performance requirements
for adhesive for structural
laminated wood products
for use under exterior
exposure condition
Specification for laminated
veneer lumber
Specification for structural
plywood
Specification for plywood
for concrete shuttering work
(second revision)
Code of practice for
preservation of plywood
and other pane products
Methods of test for wood
IS No.
(Parts 1 to 7) : 1979
(16)723: 1972
(17)451 : 1999
6736 : 1972
6739 : 1972
6760 : 1972
(18)6313
(Part 1) : 1981
(Part 2): 2001
(Part 3) : 2001
Title
based structural sandwich
construction
Specification for steel
countersunk head wire nails
(first revision)
Technical supply conditions
for wood screws (fourth
revision)
Specification for slotted
countersunk head wood
screw
Specification for slotted
round head wood screw
Specification for slotted
countersunk head wood
screws
Code of practice for anti-
termite measures in
buildings:
Constructional measures
(first revision)
Pre-constructional chemical
treatment measures (second
revision)
Treatment for existing
buildings (second revision)
50
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 3 Timber and Bamboo: 3B Bamboo
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 SYMBOLS
4 MATERIALS
5 PERMISSIBLE STRESSES
6 DESIGN CONSIDERATIONS
7 DESIGN AND TECHNIQUES OF JOINTS
8 STORAGE OF BAMBOO
ANNEX A SOURCE AND LOCAI, NAMES OF SOME OF THE SPECIES
OF BAMBOO
LIST OF STANDARDS
5
5
7
7
11
11
13
20
21
23
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
Bamboo is versatile resource characterized by high strength to weight ratio and ease in working with simple
tools. It has a long and well established tradition as a building material throughout the tropical and sub- tropical
regions. It is used in many forms of construction, particularly, for housing in rural areas. But, enough attention
had not been paid towards research and development in bamboo as had been in the case with other materials of
construction including timber. However, of late bamboo is being given its due importance and realization by
national and international organizations. A need is being felt for design and construction code in bamboo for a
number of social and trade advantages, engineering recognition and improved respectability. Forest Research
Institute, Dehra Dun and some other organizations have been engaged in bamboo research to establish its
silviculture, botanical nomenclature, entomological and pathological aspects and utilization base.
Some of the suitable species grown in India and neighbouring countries are enlisted in Annex A along with their
local names and source, for general information.
Analogous to some constructional timbers, bamboo possesses better strength-to-mass and cost ratio. Resilience
coupled with lightness makes bamboo suitable for housing in disaster-prone areas such as areas prone to earthquake.
It has the capacity to absorb more energy and show larger deflections before collapse and as such is safer under
earth tremors. At present, the application of bamboo as an engineering material is largely based on practical and
engineering experience as the design guidelines are inadequate.
The bamboo culm has a tubular structure consisting essentially of nodes and inter-nodes. In the inter-nodes the
cells are axially oriented while the nodes provide the transverse inter-connection. The disposition of the nodes
and the wall thickness are significant in imparting strength to bamboo against bending and crushing. In a circular
cross-section, bamboo is generally hollow and for structural purposes this form is quite effective and advantageous.
Each of the species of bamboo has widely different characteristics affecting its usefulness as constructional
material. The strength of bamboo culms, their straightness, lightness combined with hardness, range and size of
hollowness make them potentially suitable for a variety of applications both structural and non- structural. With
good physical and mechanical properties, low shrinkage and good average density, bamboo is well suited to
replace wood in several applications, especially in slats and panel form.
In the earlier version of this Code, timber was covered under Section 3 of Part 6 under the title Wood, which did
not cover Bamboo. In this revision, this Section has been enlarged and titled as Section 3 Timber and Bamboo.
This has been sub-divided into sub-section 3A Timber and sub-section 3B Bamboo. Bamboo has found a place
in this draft revision of the Code for the first time. This subsection pertains to bamboo and may be read in
conjunction with sub-section 3A Timber.
The information contained in this Section is largely based on the works carried out at Forest Research Institute,
Dehra Dun, Indian Plywood Industries Research and Training Institute, Bangalore, INBAR documents and the
" following Indian Standards:
IS No. Title
6874 : 1973 Method of test for round bamboo
8242 : 1976 Method of test for split bamboo
9096 : 1979 Code of practice for preservation of bamboo for structural purposes
13958 : 1994 Specification for bamboo mat board for general purposes
All standards, whether given herein above or cross-referred to in the main text of this Section, are subject to
revision. The parties to agreement based on this Section are encouraged to investigate the possibility of applying
the most recent editions of the standards.
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3B BAMBOO
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 3 Timber and Bamboo: 3B Bamboo
1 SCOPE
This Section relates to the use of bamboo for
constructional purposes in structures or elements of
the structure, ensuring quality and effectiveness of
design and construction using bamboo. It covers
minimum strength data, dimensional and grading
requirements, seasoning, preservative treatment, design
and jointing techniques with bamboo which would
facilitate scientific application and long-term
performance of structures. It also covers guidelines so
as to ensure proper procurement, storage, precautions
and design limitations on bamboo.
2 TERMINOLOGY
2.0 For the purpose of this Section, the following
definitions shall apply.
2.1 Anatomical Purpose Definitions
2.1.1 Bamboo — Tall perennial grasses found in
tropical and sub-tropical regions. They belong to the
family Poaceae and sub-family Bambusoidae.
2.1.2 Bamboo Culm — A single shoot of bamboo
usually hollow except at nodes which are often swollen.
2.1.3 Bamboo Clump — A cluster of bamboo culms
emanating from two or more rhizomer in the same
place.
2.1.4 Cellulose — A carbohydrate, forming the
fundamental material of all plants and a main source
of the mechanical properties of biological materials.
2.1.5 Cell — A fundamental structural unit of plant
and animal life, consisting of cytoplasma and usually
enclosing a central nucleus and being surrounded by a
membrane (animal) or a rigid cell wall (plant).
2.1.6 Cross Wall — A wall at the node closing the
whole inside circumference and completely separating
the hollow cavity below from that above.
2.1.7 Hemi Cellulose — The polysaccharides
consisting of only 150 to 200 sugar molecules, also
much less than the 10 000 of cellulose.
2.1.8 Lignin — A polymer of phenyl propane units,
in its simple form (C 6 H 5 CH 3 CH 2 CH 3 ).
2.1.9 Sliver — Thin strips of bamboo processed from
bamboo culm.
2.1.10 Tissue — Group of cells, which in higher plants
consist of (a) Parenchyma — a soft cell of higher plants
as found in stem pith or fruit pulp, (b) Epidermis —
the outermost layer of cells covering the surface of a
plant, when there are several layers of tissue.
2.2 Structural Purpose Definitions
2.2.1 Bamboo Mat Board — A board made of two or
more bamboo mats bonded with an adhesive.
2.2.2 Beam — A structural member which supports
load primarily by its internal resistance to bending.
2.2.3 Breaking Strength — A term loosely applied
to a given structural member with respect to the
ultimate load it can sustain under a given set of
conditions.
2.2.4 Bundle-Column — A column consisting of three
or more number of culm bound as integrated unit with
wire or strap type of fastenings.
2.2.5 Centre Internode — A test specimen having its
centre between two nodes.
2.2.6 Characteristic Load — The value of loads which
has a 95 percent probability of not exceeding during
the life of the structure.
2.2.7 Characteristic Strength — The strength of the
material below which not more than 5 percent of the
test results are expected to fall.
2.2.8 Cleavability — The ease with which bamboo
can be split along the longitudinal axis. The action of
splitting is known as cleavage.
2.2.9 Column — A structural member which supports
axial load primarily by inducing compressive stress
along the fibres.
2.2.10 Common Rafter — A roof member which
supports roof battens and roof coverings, such as
boarding and sheeting.
2.2.11 Curvature — The deviation from the
straightness of the culm.
2.2.12 Delamination — Separation of mats through
failure of glue.
2.2.13 End Distance — The distance measured
parallel to the fibres of the bamboo from the centre of
the fastener to the closest end of the member.
2.2.14 Flatten Bamboo — Bamboo consisting of culms
that have been cut and unfolded till it is flat. The culm
thus is finally spread open, the diaphragms (cross walls)
at nodes removed and pressed flat.
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3B BAMBOO
2.2.15 Full Culm — The naturally available circular
section/shape.
2.2.16 Fundamental or Ultimate Stress — The stress
which is determined on a specified type/size of culms
of bamboo, in accordance with standard practice and
does not take into account the effects of naturally
occurring characteristics and other factors.
2.2.17 Inner Diameter — Diameter of internal cavity
of a hollow piece of bamboo.
2.2.18 Inside Location — - Position in buildings in
which bamboo remains continuously dry or protected
from weather.
2.2.19 Joint — A connection between two or more
bamboo structural elements.
2.2.20 Joist — A beam directly supporting floor,
ceiling or roof of a structure.
2.2.21 Length of Internode
adjacent nodes.
Distance between
2.2.22 Loaded End or Compression End Distance —
The distance measured from the centre of the fastner
to the end towards which the load induced by the
fastener acts.
2.2.23 Matchet — A light cutting and slashing tool in
the form of a large knife.
2.2.24 Mat — A woven sheet made using thin slivers.
2.2.25 Mortise and Tenon — A joint in which the
reduced end (tenon) of one member fits into the
corresponding slot (mortise) of the other.
2.2.26 Net Section — Section obtained by deducting from
the gross cross-section (A), the projected areas of all
materials removed by boring, grooving or other means.
2.2.27 Node — The place in a bamboo culm where
branches sprout and a diaphragm is inside the culm
and the walls on both sides of node are thicker.
2.2.28 Outer Diameter — Diameter of a cross-section
of a piece of bamboo measured from two opposite
points on the outer surface.
2.2.29 Outside Location — Position in building in
which bamboos are occasionally subjected to wetting
and drying as in case of open sheds and outdoor
exposed structures.
2.2.30 Permissible Stress — Stress obtained after
applying factor of safety to the ultimate or basic stress.
2.2.31 Principal Rafter
supports purlins.
A roof member which
2.2.32 Purlins — A roof member directly supporting
roof covering or common rafter and roof battens.
2.2.33 Roof Battens — A roof member directly
supporting tiles, corrugated sheets, slates or other
roofing materials.
2.2.34 Roof Skeleton — The skelton consisting of
bamboo truss or rafter over which solid bamboo purlins
are laid and lashed to the rafter or top chord of a truss
by means of galvanized iron wire, cane, grass, bamboo
leaves, etc.
2.2.35 Slenderness Ratio — The ratio of the length of
member to the radius of gyration is known as
slenderness ratio of member. (The length of the
member is the equivalent length due to end conditions).
2.2.36 Splits — The pieces made from quarters by
dividing the quarters radially and cutting
longitudinally.
2.2.37 Taper — The ratio of difference between
minimum and maximum outer diameter to length.
2.2.38 Unloaded End Distance — The end distance
opposite to the loaded end.
2.2.39 Wall Thickness — Half the difference between
outer diameter and inner diameter of the piece at any
cross-section.
2.2.40 Wet Location — Position in buildings in which
the bamboos are almost continuously damp, wet or in
contact with earth or water, such as piles and bamboo
foundations.
2.3 Definitions Relating to Defects
2.3.1 Bamboo Bore/GHOON Hole — The defect
caused by bamboo GHOON beetle (Dinoderus spp.
Bostrychdae), which attacks felled culms.
2.3.2 Crookedness — A localized deviation from the
straightness in a piece of bamboo.
2.3.3 Discolouration — A change from the normal
colour of the bamboo which does not impair the
strength of bamboo or bamboo composite products.
2.4 Definitions Relating to Drying Degrades
2.4.1 Collapse — The defect occurring on account of
excessive shrinkage, particularly in thick walled
immature bamboo. When the bamboo wall shrinks, the
outer layers containing a larger concentration of strong
fibro-vascular bundles set the weaker interior portion
embedded in parenchyma in tension, causing the latter
to develop cracks. The interior crack develops into a
wide split resulting in a depression on the outer surface.
This defect also reduces the structural strength of round
bamboo.
2.4.2 End Splitting — A split at the end of a bamboo.
This is not so common a defect as drying occurs both
NATIONAL BUILDING CODE OF INDIA
from outer and interior wall surfaces of bamboo as
well as the end at the open ends.
2.4.3 Surface Cracking — Fine surface cracks not
detrimental to strength. However, the cracking which
occurs at the nodes reduces the structural strength.
2.4.4 Wrinkled and Deformed Surface — Deformation
in cross-section, during drying, which occurs in
immature round bamboos of most species; in thick
walled pieces, besides this deformation the outer
surface becomes uneven and wrinkled. Very often the
interior wall develops a crack below these wrinkles,
running parallel to the axis.
3 SYMBOLS
3.1 For the purpose of this Section, the following letter
symbols shall have the meaning indicated against each,
unless otherwise stated:
A = Cross-sectional area of bamboo
(perpendicular to the direction of the
principal fibres and vessels), mm 2
A=*(B 2 -d 2 )
4
D = Outer diameter, mm
d = Inner diameter, mm
E = Modulus of elasticity in bending, N/mnr
f c = Calculated stress in axial compression,
N/mm 2
f c) = Permissible stress in compression along the
fibres, N/mm 2
/ = Moment of inertia, mm 4
64
/
M
r
R'
w
Z
5
Unsupported length of column
Moisture content, percent
Radius of gyration
Modulus of rupture, N/mm 2
Wall thickness, mm
Section modulus, mm 3
Deflection or deformation, mm.
4 MATERIALS
4.1 Species of Bamboo
More than 100 species of bamboo are native to India
and a few of them are solid but most of them are hollow
in structure. Physical and mechanical properties of
20 species of bamboo so far tested in green and dry
conditions in round form are given in Table 1.
4.1.1 Grouping
Sixteen species of bamboo found suitable for structural
applications and classified into three groups, namely,
Group A, Group B and Group C are given in Table 2.
The characteristics of these groups are as given below:
Limiting Strength Values (in Green Condition)
(1)
Modulus of
Rupture (R')
N/mm 2
(2)
Modulus of Elasticity (E)
in Bending
10 3 N/mm 2
(3)
Group A
Group B
Group C
/r>70
70>/T>50
50>/T>30
E>9
9>E>6
6>E>3
4.1.2 Bamboo species may be identified using suitable
methods.
NOTE — Methods of identification of bamboo through
anatomical characters have not been perfected so far.
Identification through morphological characters could be done
only on full standing culm by experienced sorters.
4.1.3 Dendrocalamus strictus and Bambusa
arundinacea are the two principal economic species
of which the former occupies the largest area and is
the most common owing to the vast expanse and
suitability as a raw material for industrial uses.
4.2 Species of bamboo other than those listed in the
Table 2 may be used, provided the basic strength
characteristics are determined and found more than the
limits mentioned therein. However, in the absence of
testing facilities and compulsion for use of other
species, and for expedient designing, allowable stresses
may be arrived at by multiplying density with factors
as given below:
Allowable Long-Term Stress (N/mm 2 ) per
Unit Density (kg/m 3 )
Condition
Green
Axial
Compression
(no buckling)
■0.011
Air dry (12%) 0.013
Bending Shear
0.015 —
0.020 0.003
NOTE — In the laboratory regime, the density of bamboo is
conveniently determined. Having known the density of any
species of bamboo, permissible stresses can be worked out
using factors indicated above. For example, if green bamboo
has a density of 600 kg/m 3 , the allowable stress in bending
would be 0.015 x 600 = 9 N/mm 2 .
4.3 Moisture Content in Bamboo
With decrease of moisture content (M) the strength of
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3B BAMBOO
Table 1 Physical and Mechanical Properties of Indian Bamboos (in Round Form)
(Clauses 4.1 and 5.1.2)
SI
No.
Species
Properties
2
>
3
>
r
G
P
O
3
o
o
o
w
o
(1)
1,
ii
in
v
v i
vii
vin
ix
x
xi
xii
xiii;
xiv
XV
xvi;
xvn
xviii
xix;
xx
In Green Condition
(2)
Density
kg/m 3
(3)
Modulus of
Rupture
N/mm 2
(4)
Modulus of
Elasticity
ltfN/mm 2
(5)
Maximum
Compressive Strength
N/mm 2
(6)
Bambusa auriculata 594
B. balcooa 783
B. bambos (Syn.B.arundinacea) 559
B. burmanica 570
B. glancescens (Syn.B.nana) 691
B. nutans 603
B. pallida 731
B. polymorpha 619
5. fwWa 658
B. ventricosa 626
5. vulgaris 626
Cephalostachyum pergracile 601
Dendrocalamus giganteous 597
£>. hamiltonii 515
£>. longispathus 711
£>. membranacaus 551
D. st rictus 631
Melocanna baccifera 817
Oxytenanthera abyssinicia 688
Thyrsostachys oliveri 733
65.1
65.4
58.3
59.7
82.8
52,9
55.2
28.3
51.1
34.1
41.5
52.6
17.2
40.0
33.1
26.3
73.4
53.2
83.6
61.9
15.01
7.31
5.95
11.01
14.77
6.62
12.90
3.12
7.98
3.38
2.87
11.16
0.61
2.49
5.51
2.44
11.98
11.39
14.96
9.72
36.7
46.7
35.3
39.9
53.9
45.6
54.0
32.1
40.7
36.1
38.6
36.7
35.2
43.4
42.1
40.5
35.9
53.8
46.6
46.9
Density
kg/m 3
(7)
670
663
672
673
659
722
640
684
664
728
751
758
In Air Dry Conditions
Modulus of
Modulus
Rupture
of Elasticity
N/mm 2
10 3 N/mm 2
(8)
(9)
89.1
80.1
105.0
52.4
35.5
66.7
71.3
47.8
37.8
119.1
57.6
90.0
NOTES
1 As the strength of split bamboo is more than that of round bamboo, the results of tests on round bamboo can be safely used for designing with spit bamboo.
2 The values of stress in N/mm 2 have been obtained by converting the values in kgf/cm 2 t>y dividing the same by 10.
21.41
8.96
17.81
10.72
4.40
10.07
19.22
6.06
3.77
15.00
12.93
12.15
Table 2 Safe Working Stresses of Bamboos for Structural Designing 1 *
(Clauses 4.1.1, 4.2, 5.3 and 5.4)
SI
Species
Extreme Fibre Stress
Modulus of
Allowable
No.
in Bending
Elasticity
Compressive Stress
N/mm 2
I0 3 N/mm 2
N/mm 2
(1)
(2)
(3)
(4)
(5)
GROUP A
i)
Bambusa glancescens (syn. B.
nana)
20.7
3.28
15.4
ii)
Dendrocalamus strictus
18.4
2.66
10.3
iii)
Oxytenanthera abyssinicia
GROUP B
20.9
331
13.3
iv)
Bambusa balcooa
16.4
1.62
13.3
v)
B. pallida
13.8
2.87
15.4
vi)
B. nutans
13.2
1.47
13.0
vii)
B. tulda
12.8
1.77
11.6
viii)
B. auriculata
16.3
3.34
10.5
ix)
B. burmanica
14.9
2.45
11.4
x)
Cephalostachyum pergracile
13.2
2.48
10.5
xi)
Melocanna baccifera (Syn. M.
bambusoides)
13.3
2.53
15.4
xii)
Thy rso ta chys o live ri
GROUP C
15.5
2.16
13.4
xiii)
Bambusa arundinacea (Syn. B
. bambos)
14.6
1.32
10.1
xiv)
B. ventricosa
8.5
0.75
10.3
xv)
B. vulgaris
10.4
0.64
11.0
xvi)
Dendrocalamus longispathus
8.3
1.22
12.0
NOTE — The values of stress in Is
I/mm 2 have been obtained by converting the values in kgf/cm 2 by dividing the
of bamboo in green condition.
same by 10.
l) The values given pertain to testing <
bamboo increases exponentially and bamboo has an
intersection point (fibre saturation point) at around 25
percent moisture content depending upon the species.
A typical moisture-strength relationship is given at
Fig. 1. The moisture content of bamboo shall be
determined in accordance with good practice [6-3B(l)].
Matured culms shall be seasoned to about 20 percent
moisture content before use.
4.3.1 Air seasoning of split or half-round bamboo does
not pose much problem but care has to be taken to
prevent fungal discolouration and decay. However,
rapid drying in open sun can control decay due to
fungal and insect attack. Seasoning in round form
presents considerable problem for several of Indian
species of bamboo as regards mechanical degrade due
to drying defects.
NOTE — A general observation has been that immature bamboo
gets invariably deformed in cross-section during seasoning and
thick walled immature bamboo generally collapses. Thick
mature bamboo tends to crack on the surface, with the cracks
originating at the nodes and at the decayed points. Moderately
thick immature and thin and moderately thick mature bamboos
season with much less degrade. Bamboo having poor initial
condition on account of decay, borer holes, etc generally suffers
more drying degrades.
4.3,2 Accelerated air seasoning method gives good
results. In this method, the nodal diaphragm (septa)
are punctured to enable thorough passage of hot air
from one end of the resulting bamboo tube to the other
end.
NOTE — For details, reference may be made to relevant
publications of Forest Research Institute, Dehra Dun.
4.4 Grading of Structural Bamboo
4.4,1 Grading is sorting out bamboo on the basis of
characteristics important for structural utilization as
under:
a) Diameter and length of culm,
b) Taper of culm,
c) Straightness of culm,
d) Inter nodal length,
e) Wall thickness,
f) Density and strength, and
g) Durability and seasoning.
One of the above characteristics or sometimes
combination of 2 or 3 characteristics form the basis of
grading. The culms shall be segregated species-wise.
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3B BAMBOO
x 10
1-541-
1-40
1 26
N
£ M2
-0-981-
to
in
E 0-8 Al-
io
| 070
x
10
§ 0-56
| 042
X
<
0-28-
OH
10 20 30 40 50 60
MOISTURE CONTENT, •/•
70
80 90 100 110
Fig. 1 Moisture Strength Relationship Bambusa Nutans (Bamboo)
4.4.2 Diameter and Length
4.4.2.1 Gradation according to the mean outer
diameter
For structural Group A and Group B species, culms
shall be segregated in steps of 10 mm of mean outer
diameter as follows:
Special Grade 70 mm < Diameter < 100 mm
Grade I 50 mm < Diameter < 70 mm
Grade II 30 mm < Diameter < 50 mm
Grade III Diameter < 30 mm
For structural Group C species culms shall be
segregated in steps of 20 mm of mean outer diameter
Grade I 80 mm < Diameter < 100 mm
Grade II 60 mm < Diameter < 80 mm
Grade III Diameter < 60 mm
4.4.2.2 The minimum length of culms shall be
preferably 6 m for facilitating close fittings at joints, etc.
4.4.3 Taper
The taper shall not be more than 5.8 mm per metre
length (or 0.58 percent) of bamboo in any grade of
bamboo.
4.4.4 Curvature
The maximum curvature shall not be more than 75 mm
in a length of 6 m of any grade of bamboo.
4.4.5 Wall Thickness
Preferably minimum wall thickness of 8 mm shall be
used for load bearing members.
4.4.6 Defects and Permissible Characteristics
4.4.6.1 Dead and immature bamboos, bore/GHOON
10
NATIONAL BUILDING CODE OF INDIA
holes, decay, collapse, checks more than 3 mm in
depth, shall be avoided.
4.4.6.2 Protruded portion of the nodes shall be flushed
smooth. Bamboo shall be used after at least six weeks
of felling. Bamboo shall be properly treated in
accordance with good practice [6-3B(2)].
4.4.6.3 Broken, damaged and discoloured bamboo
shall be rejected.
4.4.6.4 Matured bamboo of at least 4 years of age shall
be used.
4.5 Durability and Treatability
4.5.1 Durability
The natural durability of bamboo is low and varies
between 12 months and 36 months depending on the
species and climatic conditions. In tropical countries
the biodeterioration is very severe. Bamboos are
generally destroyed in about one to two years' time
when used in the open and in contact with ground
while a service life of two to five years can be
expected from bamboo when used under cover and
out of contact with ground. The mechanical strength
of bamboo deteriorates rapidly with the onset of
fungal decay in the sclerenchymatous fibres. Split
bamboo is more rapidly destroyed than round
bamboo. For making bamboo durable, suitable
treatment shall be given.
4.5.2 Treatability
Due to difference in the anatomical structure of bamboo
as compared to timber, bamboo behaves entirely
differently from wood during treatment with
preservative. Bamboos are difficult to treat by normal
preservation methods in dry condition and therefore
treatment is best carried out in green condition in
accordance with good practice [6-3B(2)].
4.5.2.1 Boucherie Process
In this process of preservative treatment, water borne
preservative is applied to end surface of green bamboo
through a suitable chamber and forced through the
bamboo by hydrostatic or other pressure.
4.5.2.2 Performance of treated bamboo
Trials with treated bamboos have indicated varied
durability depending upon the actual location of use.
The performance in partially exposed and under
covered conditions is better.
4.5.2.3 For provisions on safety of bamboo structures
against fire, see Part 7 'Constructional Practices and
Safety'.
5 PERMISSIBLE STRESSES
5.1 Basic stress values of different species and groups
of bamboo shall be determined according to good
practice [6-3B(3)]. These values shall then be divided
by appropriate factors of safety to obtain permissible
stresses.
5.1.1 The safety factor for deriving safe working
stresses of bamboo shall be as under:
Extreme fibre stress in beams - 4
Modulus of elasticity - 4.5
Maximum compressive stress parallel - 3.5
to grain/fibres
5.1.2 The coefficient of variation (in percent), which
has been arrived based on data of test-results of at least
15 consignments of bamboo in green conditions, shall
be as under:
Property
(i)
Mean
(2)
Range Maximum
Expected
Value
(3)
(4)
Modulus of rupture
Modulus of
elasticity
Maximum
compressive stress
15.9 5.7-28.3 23.4
21.1 12.7-31.7 27.4
14.9 7.6-22.8 20.0
The maximum expected values of coefficient of
variation which are the upper confidence limits under
normality assumption such that with 97.5 percent
confidence the actual strength of the bamboo culm will
be at least 53 percent of the average reported value of
modulus of rupture in Table 1 .
5.2 Solid bamboos or bamboos whose wall thickness
(w>) is comparatively more and bamboos which are
generally known as male bamboos having nodes very
closer and growing on ridges are often considered good
for structural purposes.
5.3 The safe working stresses for 16 species of
bamboos are given in Table 2.
5.4 For change in duration of load other than
continuous (long-term), the permissible stresses given
in Table 2 shall be multiplied by the modification
factors given below:
For imposed or medium term loading - 1.25
For short-term loading - 1 .50
6 DESIGN CONSIDERATIONS
6.1 All structural members, assemblies or framework
in a building shall be capable of sustaining, without
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3B BAMBOO
11
exceeding the limits of stress specified, the worst
combination of all loadings. A fundamental aspect of
design will be to determine the forces to which the
structure/structural element might be subjected to,
starting from the roof and working down to the soil by
transferring the forces through various components and
connections. Accepted principles of mechanics for
analysis and specified design procedures shall be
applied (see Part 6 'Structural Design, Sub-section 3A
Timber').
6.2 Unlike timber, bamboo properties do not relate
well to species, being dependent among other factors,
on position of the culm, geographic location and age.
The practice in timber engineering is to base designs
on safe working stresses and the same may be adopted
to bamboo with the limitations that practical experience
rather than precise calculations generally govern the
detailing.
6.3 Net Section
It is determined by passing a plane or a series of
connected planes transversely through the members.
Least net sectional area is used for calculating load
carrying capacity of a member.
6.4 Loads
6.4.1 The loads shall be in accordance with Part 6
'Structural Design, Section 1 Loads, Forces and
Effects 5 .
6.4.2 The worst combination and location of loads
shall be considered for design. Wind and seismic forces
shall not be considered to act simultaneously.
6.5 Structural Forms
6.5.1 Main structural components in bamboo may
include roof and floor diaphragms, shear walls, wall
panellings, beams, piles, columns, etc. Both from the
point of view of capacity and deformation, trusses and
framed skeltons are much better applications of
bamboo.
6.5.2 Schematization of Bamboo as a Structural
Material
This shall be based on the principles of engineering
mechanics involving the following assumptions and
practices:
a) The elastic behaviour of bamboo, till failure;
(plastic behaviour being considered
insignificant);
b) Bamboo culms are analysed on mean wall
thickness basis as hollow tube structure (not
perfectly straight) member on mean diameter
basis;
c) The structural elements of bamboo shall be
appropriately supported near the nodes of
culm as and where the structural system
demands. The joints in the design shall be
located near nodes; and
d) Bamboo structures be designed like any other
conventional structural elements taking care
of details with regards to supports and joints;
they shall be considered to generally act as a
hinge, unless substantiating data justify a
fixed joint.
6.6 Flexural Members
6.6.1 All flexural members may be designed using the
principles of beam theory.
6.6.2 The deflection shall be within the prescribed
limits. The tendency of bamboo beams to acquire a
large deflection under long continuous loadings due
to possible plastic flow, if any shall be taken care of.
Permanent load may be doubled for calculation of
deflection under sustained load (including creep) in
case of green bamboo having moisture content
exceeding 15 percent.
6.6.3 Bamboo is not naturally reinforced for
shear, because, compared to reinforced cement
concrete beam, the stirrups are located on the
longitudinal instead of the transverse direction in a
bamboo culm.
6.6.4 The moment of inertia, / shall be determined as
follows:
a) The outside diameter and the wall thickness
shall be measured at both ends, correct up to
1 mm for diameter of culm and 0. 1 mm for
the wall thickness. (For each cross-section the
diameter shall be taken twice, in direction
perpendicular to each other and so the wall
thickness shall be taken as four times, in the
same places as the diameter has been taken
twice.)
b) With these values the mean diameter and the
mean thickness for the middle of the beam
shall be calculated and moment of inertia
determined.
6.6.4.1 The maximum bending stress shall be
calculated and compared with the allowable stress.
6.6.4.2 The deflection shall be calculated, and
compared with the allowable deflection. The initial
curvature shall be considered in the calculation of the
deflection.
6.6.4.3 The shear stress in the neutral layer at the small
end shall be checked, if the length of the beam is less
12
NATIONAL BUILDING CODE OF INDIA
than 25 times the diameter at that end. For shear checks,
conventional design procedure in accordance with
Part 6 'Structural Design, Sub-section 3A Timber'
shall be followed,
NOTE — The basic shear stress values (N/mm 2 ) for at least
five species of bamboo in split form in green condition have
been determined as under:
Bambusa pallida 9.77
B. Vulgaris 9.44
Dedrocalamus giganteous 8.86
D.hamiltonii 1 .11
Oxytenanthera abyssinicia 11.2
6.6.4.4 Forces acting on a beam, being loads or
reaction forces at supports, shall act in nodes or as near
to nodes as by any means possible.
6.7 Bamboo Columns (Predominantly Loaded in
Axial Direction)
6.7.1 Columns and struts are essential components
sustaining compressive forces in a structure. They
transfer load to the supporting media.
6.7.2 Design of columns shall be based on one of the
following two criteria:
a) Full scale buckling tests on the same species,
size and other relevant variables.
b) Calculations, based on the following:
1 ) The moment of inertia shall be as per 6.6.4 .
2) For bamboo columns the best available
straight bamboo culms shall be selected.
Structural bamboo components in
compression should be kept under a
slenderness ratio of 50.
3) The bending stresses due to initial
curvature, eccentricities and induced
deflection shall be taken into account, in
addition to those due to any lateral
load.
6.7.3 Buckling calculation shall be according to Euler,
with a reduction to 90 percent of moment of inertia, to
take into account the effect of the taper provided it is
not less than 0.6 percent.
6.7.4 For strength and stability, larger diameter thick
walled sections of bamboo with closely spaced nodes
shall be used. Alternatively, smaller sections may be
tied together as a bundle-column.
6.8 Assemblies, Roof Trusses
6.8.1 Elements in structure are generally built-up in
the form of assembled members for which a triangle is
a simple figure of stability. Besides sloped chords,
parallel chord construction is also appropriate as
external profile.
6.8.2 A truss is essentially a plane structure which is
very stiff in the plane of the members, that is the plane
in which it is expected to carry load, but very flexible
in every other direction. Roof truss generally consists
of a number of triangulated frames, the members of
which are fastened at ends and the nature of stresses at
joints are either tensile or compressive and designed
as pin-ended joints (see Fig. 2A). Bamboo trusses
may also be formed using bamboo mat board or
bamboo mat- veneer composite or plywood gusset (see
Fig. 2B).
6.8.3 Truss shall be analysed from principles of
structural mechanics for the determination of axial
forces in members. For the influence of eccentricities,
due allowance shall be made in design.
6.8.4 The truss height shall exceed 0. 15 times the span
in case of a triangular truss (pitched roofing) and
0.10 times the span in case of a rectangular (parallel)
truss.
6.8.5 For members in compression, the effective
length for in-plane strength verification shall be
taken as the distance between two adjacent points
of contraflexure. For fully triangulated trusses,
effective length for simple span members without
especially rigid end-connection shall be taken as the
span length.
6.8.6 For strength verification of members in
compression and connections, the calculated axial
forces should be increased by 10 percent.
6.8.7 The spacing of trusses shall be consistent with
use of bamboo purlins (2 m to 3 m).
6.8.8 The ends in open beams, joists, rafters, purlins
shall be suitably plugged. Bamboo roof coverings shall
be considered as non-structural in function. The
common roof covering shall include bamboo mat
board, bamboo mat corrugated sheet, bamboo tiles/
strings, plastered bamboo reeds, thatch, corrugated
galvanized iron sheeting, plain clay tiles or pan tiles,
etc.
7 DESIGN AND TECHNIQUES OF JOINTS
7.1 Connecting the load-bearing elements together for
effective transfer of stress is one of the serious problems
confronted by the engineers. The size of the members
in a structure depends not only on the direct loads they
are required carry, but also on the ability to join the
members together. Joints are quite critical in
assemblies, and these should be stable in relation to
time. The main objective is to achieve continuity
between elements with controlled displacements. As
joints are a source of weakness in any bamboo
structure, they have to be made as strong and rigid as
possible.
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3B BAMBOO
13
2A - PIN ENDED JOINT TRUSSES
GUSSET (TYPICAL)
2B GUSSET JOINT TRUSSES
Fig. 2 Some Typical Configurations for Small and Large Trusses in Bamboo
14
NATIONAL BUILDING CODE OF INDIA
7.2 Bamboo Joints
Efficient jointing is basic to the structural adequacy of
a framed construction, may it be of any cellulosic
material. Round, tubular form of bamboo requires an
approach different to that used for sawn timber.
Susceptibility to crushing at the open ends, splitting
tendency, variation in diameter, wall thickness and
straightness are some of the associated issues which
have to be taken care of while designing and detailing
the connections with bamboo.
7.2.1 Traditional Practices
Such joining methods revolve around lashing or tying
by rope or string with or without pegs or dowels. Such
joints lack stiffness and have low efficiency.
7.2.1.1 Lengthening joints (end jointing)
7.2.1.1.1 Lap joint
In this case, end of one piece of bamboo is made to lap
over that of the other in line and the whole is suitably
fastened. It may be full lapping or half lapping. Full
section culms are overlapped by at least one internode
and tied together in two or three places. Efficiency
could be improved by using bamboo or hardwood
dowels. In half lapping, culms shall preferably be of
similar diameter and cut longitudinally to half depth
over at least one internode length and fastened as per
full lap joint (see Fig. 3).
7.2.1.1.2 Butt joints
Culms of similar diameter are butted end to end, inter-
connected by means of side plates made of quarter-
round culm of slightly large diameter bamboo, for two
or more internode lengths. Assembly shall be fixed
and tied preferably with dowel pins. This joint transfers
both compressive and tensile forces equally well (see
Fig. 4).
7.2.1.1.3 Sleeves and inserts
Short length of bamboo of appropriate diameter may
be used either externally or internally to join two culms
together (see Fig. 5).
7.2.1.1.4 Scarf joints
A scarf joint is formed by cutting a sloping plane 1 in
4 to 6 on opposite sides from the ends of two similar
diameter bamboo culms to be joined. They shall be
lapped to form a continuous piece and the assembly
suitably fastened by means of lashings. Using hooked
splays adds to the strength and proper location of joints
(see Fig. 6).
£
3
3A FULL - LAPPED SPLICED JOINT
(OVER - LAPPED ATLEAST ONE INTERNODE)
BAMBOO OR
HARDWOOD DOWEL -
3B HALF - LAPPED SPLICED JOINT
(SIMILAR DIAMETER; ONE INTERNODE LENGTH)
£
-rftr
llll
III)
-4**-
i ti
■CE>
i u
1 "
1 1
1 1
3
3C LAPPED SPLICED JOINT WITH PEGS AND BATTENS
Fig. 3 Lap Joints in Bamboo
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3B BAMBOO
15
HOLES FOR DOWELS
OR PINS
Fig. 4 Butt Joint with Side Plates in Bamboo
B
G
B
□
B
LENGTHENING JOINT
Fig. 5 Sleeves and Inserts for Bamboo Joints
Fig. 6 Scarf Joint
16
NATIONAL BUILDING CODE OF INDIA
7.2.1.2 Bearing joints
7.2.1.2.2 Tenon joint
For members which either bear against the other or
cross each other and transfer the loads at an angle other
than parallel to the axis, bearing joints are formed.
7.2.1.2.1 Butt joints
The simplest form consists of a horizontal member
supported directly on top of a vertical member. The
top of the post may be cut to form a saddle to ensure
proper seating of beam for good load transfer. The
saddle should be close to a node to reduce risk of
splitting (see Fig. 7).
It is formed by cutting a projection (tenon) in walls of
one piece of bamboo and filling it into corresponding
holes (mortise) in another and keyed. It is a neat and
versatile joint for maximum strength and resistance to
separation (see Fig. 8).
7.2.1.2.3 Cross over joint
It is formed when two or more members cross at right
angles and its function is to locate the members and
to provide lateral stability. In case of the joint
connecting floor beam to post, it may be load bearing
£
3 Q
HORIZONTAL MEMBER
"VERTICAL
MEMBER
j [/-SADDLE
"X
•NODE
ffi
J P
"HOLE FOR PIN
7A SADDLE (BUTT) JOINT
(SADDLE TO BE CLOSE TO THE
NODE)
SQUARE
NOTCHED
ENDS & TENONS
*'£k=
C
A
3
3
"SIDE PLATE
7B VARIATIONS ON SADDLE JOINT
Fig. 7 Butt Joints in Bamboo
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3B BAMBOO
17
£ra
]
TENON AND KEY JOINT
r<p
INTEGRAL TENON (HORNED) JOINT
Fig. 8 Tenon Joint
(see Fig. 9). Such joints are also used to transmit angle
thrust.
7.2 .1 .3 Angled joints
When two or more members meet or cross other than
at right angles, angled joints are formed. For butt joints,
the ends of the members may be shaped to fit in as
saddle joints. Tenons would help in strengthening such
joints (see Fig. 10).
7.2.2 Modern Practices (see Fig. 11)
Following are some of the modern practices for
bamboo jointing:
a) Plywood or solid timber gusset plates may be
used at joint assemblies of web and chord
connection in a truss and fixed with bamboo
pins or bolts. Hollow cavities of bamboo need
to be stuffed with wooden plugs.
b) Use of wooden inserts to reinforce the ends
of the bamboo before forming the joints.
Alternatively steel bands clamps with integral
bolt/eye may be fitted around bamboo
sections for jointing.
7.2.3 Fixing Methods and Fastening Devices
In case of butt joints the tie may be passed through a
pre-drilled hole or around hardwood or bamboo pegs
or dowels inserted into preformed holes to act as horns.
Pegs are driven from one side, usually at an angle to
increase strength and dowels pass right through the
member, usually at right angles.
7.2.3.1 Normally 1.60 mm diameter galvanized iron
wire may be used for tight lashing.
7.2.3.2 Wire bound joints
Usually galvanized iron 2.00 mm diameter galvanized
iron wire is tightened around the joints by binding the
respective pieces together. At least two holes are drilled
in each piece and wire is passed through them for good
results.
18
NATIONAL BUILDING CODE OF INDIA
PURLIN
NODE
DOWEL
£
RAFTER
BEAM SUPPORTED ON SHORT
CULM TIED TO POST
II
U
Q<
DOWELLED AND
TIED JOINT
PEGGED AND
TIED JOINT
I
PURLIN
I IN -7
jL
3
RAFTER
ALTERNATIVE PURLIN - RAFTER CONNECTION
Fig. 9 Cross Over Joints (Bearing Joints)
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3B BAMBOO
19
Fig. 10 Angled Joint with Integral Tenons
RAFTER
BAMBOO PURLIN
BOTTOM
CHORD
WEB
Fig. 11 Gusset Plated Joints
7.2.3.3 Pin and wire bound joints
Generally 12 mm dia bamboo pins are fastened to
culms and bound by 2.00 mm diameter galvanized iron
wire.
7.2.3.4 Fish plates/gusset plated joints
At least 25 mm thick hardwood splice plate or 12 mm
thick structural grade plywood are used. Solid bamboo
pins help in fastening the assembly.
7.2.3.5 Horned joints
Two tongues made at one end of culm may be fastened
with a cross member with its mortise grooves to receive
horns, the assembly being wire bound.
7.2.4 For any complete joint alternative for a given
load and geometry, description of all fastening
elements, their sizes and location shall be indicated.
Data shall be based on full scale tests.
7.2.5 Tests on full scale joints or on components shall
be carried out in a recognized laboratory.
7.2.6 In disaster high wind and seismic areas, good
construction practice shall be followed taking care of
joints, their damping and possible ductility. Bracings
in walls shall be taken care of in bamboo structures.
8 STORAGE OF BAMBOO
Procurement and storage of bamboo stocks are
essential for any project work and shall be done in
accordance with Part 7 'Constructional Practices and
Safety'.
20
NATIONAL BUILDING CODE OF INDIA
ANNEX A
{Foreword)
SOURCE AND LOCAL NAMES OF SOME OF THE SPECIES OF BAMBOO
SI No.
(1)
Species
(2)
1 . Bambusa auriculata
2. B. balcooa
3. B. bambos (Syn. B. arundinacea)
4. B. burmanica
5. B. multiplex
Syn. B. glancescens (Syn. B. nana)
6. B. nutans
7. B. pallida
8. B. polymorpha
9. £. tulda
Source/Local Names
(3)
Assam, Bangladesh, Myanmar; introduced in Calcutta
Botanic Garden.
Asm — Baluka;
Ben — Balku bans;
Duars — Bora bans;
Garo — Wamnah, beru;
Tripura — Barak.
Asm — Kotoba;
Ben — Baroowa, behor; ketuas; ketwa
Manip — Saneibi;
Man — Katang bamboo, oowga;
Oriya — Daba, katuig;
Tel — Mulkas veduru, Mullu vedurn;
English — Spiny bamboo.
Asm — Thaikawa.
Sans — keu-fa;
Burmese — Pa-lau-pinan-wa;
Malay — Bamboo tjeenah;
China — Bamboo hower tjeenah.
Assam — Deobans, jotia-makal;
Asm — Bidhuli, mukial;
Ben — Makia;
Bhutia — Jiu;
Hin — Malabans;
Kangra — Nal;
Khasi — Seringjai;
Kuki — Wa malang;
Lepcha — Malubans, mahlu, mallo;
Oriya — Badia bansa;
Sylhet (Banglaesh) — Peechli;
Tripura — Kali
Asm — Bijli, jowa, makal, walkthai;
Cachar — Bakhal, burwal;
Khasi — Seskien, skhen, ineng, usker;
Lepcha — Pashipo, pshi, pushee;
Mikir — Loto;
Naga — Tesero, watoi;
Tripura — Makal.
Asm — Jama betwa, betwa;
Ben — Batua, jaibarouwa, jama;
Burma — Kyathaung-wa;
MP-Korku — Narangi bhas;
Tripura — Basi.
Asm — Wamunna, wagi, nal-bans;
Beng — Tulda, jowa;
Duars — Karanti, matela;
Garo — Watti;
Hin — Peka;
Kamrup — Bijuli, jati, joo, ghora;
Tripura — Mirtinga
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3B BAMBOO
21
(1)
(2)
(3)
10. B. vulgaris
11. B. Wamin Syn. B. ventricosa
(Syn. B. Vulgaris var. Wamin)
1 2 . Cephalostachyum pergacile
1 3 . Dendrocalamus giganteous
14. D. hamiltonii
15. D. longispathus
16. D. membranaceus
17. D. strictus
18. Melocanna baccifera
19. Oxytenanthera abyssinicia
20. Thyrsostachys oliveri
Ben and Manipuri — Bakal;
Oriya — Sunarkania bans.
Common name — Pitcher bamboo.
MP — Bhalanbans;
Manipuri — Wootang;
Naga — Latang;
Oriya — Darrgi.
English — Giant Bamboo;
Asm — Worra;
Manipuri — Maroobeb.
Nep — Tamo;
Asm — Kokwa;
Tripura — Pecha.
Tripura — Rupai.
Native of Myanmar; introduced in Kerala.
English — Male bamboo;
Ben — Karail;
Guj — Nakur bans;
Kan — Kiri bidiru;
Mah — Male bamboo, nanvel;
Oriya — Salia;
Tarn — Kalmungil;
Tel — Sadanapa vedur;
Tripura — Lathi bans;
Hin — Bans Kaban, nav bans;
Asm — Tarai;
Ben — Muli;
Cachar — Wati;
Garo — Watrai;
Manipuri — Moubi;
Mikir — Artem;
Naga — Turiah.
Native of tropical Africa; cultivated at FRI, Dehra Dun.
Native of Myanmar; Planted in Haldwani (Uttaranchal);
Arunachal Pradesh, Kerala and Tamil Nadu.
NOTES
1 The following abbreviations have been used in the above table:
Asm
—
Assam
Ben
—
Bengali
Guj
—
Gujarati
Hin
—
Hindi
Kan
—
Kannada
Mah
—
Maharashtra
Manip
—
Manipur
MP
—
Madhya Pradesh
Nep
—
Nepali
Sans
—
Sanskrit
2 The above table does not provide an exhaustive list It only attempts to enlist some of the information readily available in regard to
species of bamboo from India and some of the neighbouring countries, and some connected information.
22
NATIONAL BUILDING CODE OF INDIA
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and 'accepted standards'
in the fulfillment of the requirements of this Code. The
latest version of a standard shall be adopted at the time
of enforcement of the Code. The standards listed may
be used by the Authority as a guide in conformance
with the requirements of the referred clauses in the
Code.
/5JVc
).
(1)
6874:
1973
(2)
9096:
1979
(3)
6874 :
1973
8242:
1976
Title
Method of test for round bamboo
Code of practice for preservation
of bamboo for structural purposes
Method of test for round bamboo
Method of test for split bamboo
PART 6 STRUCTURAL DESIGN — SECTION 3 TIMBER AND BAMBOO: 3B BAMBOO
23
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 4 Masonry
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 MATERIALS
4 DESIGN CONSIDERATIONS
5 STRUCTURAL DESIGN
6 GENERAL REQUIREMENTS
7 SPECIAL CONSIDERATION IN EARTHQUAKE ZONES
8 GUIDELINES FOR IMPROVING EARTHQUAKE RESISTANCE OF
LOW STRENGTH MASONRY BUILDINGS
9 REINFORCED BRICK AND REINFORCED BRICK CONCRETE FLOORS
AND ROOFS
10 NOTATIONS AND SYMBOLS
ANNEX A SOME GUIDELINES FOR ASSESSMENT OF ECCENTRICITY
OF LOADING ON WALLS
ANNEX B CALCULATION OF BASIC COMPRESSIVE STRESS OF
MASONRY BY PRISM TEST
ANNEX C GUIDELINES FOR DESIGN OF MASONRY SUBJECTED TO
CONCENTRATED LOADS
ANNEX D GUIDELINES FOR APPROXIMATE DESIGN OF NON-LOAD
BEARING WALL
ANNEX E NOTATIONS, SYMBOLS AND ABBREVIATIONS
LIST OF STANDARDS
5
5
7
9
18
22
24
33
38
38
39
39
40
41
42
42
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
This Section primarily covers the structural design of unreinforced masonry elements in buildings. However,
provisions on reinforced brick and reinforced brick concrete floors and roofs have also been included.
This Section was first published in 1970 and revised in 1983. Subsequently the first revision of this Section was
modified in 1987 through Amendment No. 2 to bring this Section in line with the latest revised masonry Code. In
this amendment, certain provisions were updated following the revision of IS 1905 'Code of practice for structural
use of unreinforced masonry' on which the earlier version was based. In the amendment, requirements of masonry
element for stability were modified; in the design of free standing wall, provisions were made for taking advantage
of the tensile resistance in masonry under certain conditions; provision regarding effective height of masonry
wall between openings was modified; method of working out effective height of wall with a membrane type
DPC was modified; the criteria for working out effective length of wall having openings was modified; some
general guidelines for dealing with concentrated loads for design of walls were included; and provision of cutting
and chases in walls were amplified.
As a result of experience gained in the implementation of this Section and feedback received, as well as in view
of revision of IS 4326 'Code of practice for earthquake resistant design and construction of buildings' and
formulation of some new standards in this field, a need to revise this Section has been felt. This revision has,
therefore, been prepared to take care of these aspects. The significant changes incorporated in this revision
include the following:
a) The provision of special considerations in earthquake zones have been aligned in line with IS 4326 : 1993.
b) A new clause covering guidelines for improving earthquake resistance of low strength masonry buildings
has been added.
c) Reference to design of reinforced brick and reinforced brick concrete floors and roofs has been included.
d) Reference to all the concerned Indian Standards have been updated.
Structural design requirements of this Section are based on IS 1905 : 1987 'Code of practice for structural use of
unreinforced masony (third revision)' and IS 4326 : 1993 'Code of practice for earthquake resistant design and
construction of buildings (second revision)".
A reference to SP 20 : 1991 'Handbook on masonry design and construction (first revision)' may be useful.
All standards, whether given herein above or cross-referred to in the main text of this Section, are subject to
revision. The parties to agreement based on this Section are encouraged to investigate the possibility of applying
the most recent editions of the standards.
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 4 Masonry
1 SCOPE
1.1 This Section primarily covers the structural design
aspects of unreinforced load bearing and non-load
bearing walls, constructed with masonry units
permitted in accordance with this Section. This,
however, also covers provisions for design of
reinforced brick and reinforced brick concrete floors
and roofs. It also covers guidelines regarding
earthquake resistance of low strength masonry
buildings.
1.2 The recommendations of the Section do not apply
to walls constructed in mud mortars.
2 TERMINOLOGY
2.1 For the purpose of this Section, the following
definitions shall apply,
2.1.1 Bed Block — A block bedded on a wall, column
or pier to disperse a concentrated load on a masonry
element.
2.1.2 Bond — Arrangement of masonry units in
successive courses to tie the masonry together both
longitudinally and transversely; the arrangement is
usually worked out to ensure that no vertical joint of
one course is exactly over the one in the next course
above or below it, and there is maximum possible
amount of lap.
2.1.3 Column, Pier and Buttress
a) Column — An isolated vertical load bearing
member, width of which does not exceed four
times the thickness.
b) Pier — A thickened section forming integral
part of a wall placed at intervals along the
wall, to increase the stiffness of the wall or to
carry a vertical concentrated load. Thickness
of a pier is the overall thickness including the
thickness of the wall or, when bonded into a
leaf of a cavity wall, the thickness obtained
by treating that leaf as an independent wall
(see Fig. 1).
c) Buttress — A pier of masonry built as an
integral part of wall and projecting from either
or both surfaces, decreasing in cross-sectional
area from base to top.
2.1.4 Cross-Sectional Area of Masonry Unit — Net
cross-sectional area of a masonry unit shall be taken
as the gross cross-sectional area minus the area of
cellular space. Gross cross-sectional area of cored units
shall be determined to the outside of the coring but
cross-sectional area of grooves shall not be deducted
from the gross cross-sectional area to obtain the net
cross-sectional area.
2.1.5 Curtain Wall — A non-load bearing wall subject
to lateral loads. It may be laterally supported by vertical
or horizontal structural members where necessary (see
Fig. 2).
2.1.6 Effective Height — The height of a wall or
column, to be considered for calculating slenderness
ratio.
2.1.7 Effective Length — The length of a wall to be
considered for calculating slenderness ratio.
2.1.8 Effective Thickness — The thickness of a wall
or column to be considered for calculating slenderness
ratio.
2.1.9 Hollow Unit — A masonry unit of which net
cross-sectional area in any plane parallel to the bearing
surface is less than 75 percent of its gross cross-
sectional area measured in the same plane.
2.1.10 Grout — Mortar of pourable consistency.
2.1.11 Joint — A junction of masonry units.
a) Bed joint — A horizontal mortar joint upon
which masonry units are laid.
b) Cross joint — A vertical joint, normal to the
face of the wall.
c) Wall joint — A vertical joint parallel to the
face of the wall.
2.1.12 Leaf — Inner or outer section of a cavity wall.
2.1.13 Lateral Support — A support which enables a
masonry element to resist lateral load and/or restrains
lateral deflection of a masonry element at the point of
support.
2.1.14 Load Bearing Wall +- A wall designed to carry
an imposed vertical load in addition to its own weight,
together with any lateral load.
2.1.15 Masonry — An assemblage of masonry units
properly bonded together with mortar.
2.1.16 Masonry Unit — Individual units which are
bonded together with the help of mortar to form a
masonry element such as wall, column, pier, buttress,
etc.
2.1.17 Partition Wall — An interior non-load bearing
wall, one storey or part storey in height.
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
THICKNESS OF PIER, fp
WIDTH OF PIER, wp WIDTH OF PIER, vvp
Fig. 1 Definition of Pier
-RCC SLAB
"W
RCC COLUMN-
J-?^ l V.i. , -J^.U-*-l
r u i
I
-HINGED JOINT
(DIAGRAMMATIC)
V
CURTAIN
^ WALL
"^3*"
Fig. 2 Masonry Curtain Wall
2.1.18 Panel Wall — An exterior non-load bearing
wall in framed construction, wholly supported at each
storey but subjected to lateral loads.
2.1.19 Shear Wall — A wall designed to carry
horizontal forces acting in its plane with or without
vertical imposed loads.
2.1.20 Slenderness Ratio — Ratio of effective height
or effective length to effective thickness of a masonry
element.
2.1.21 Types of Walls
a) Cavity wall — A wall comprising two leaves,
each leaf being /built of masonry units and
separated by a cavity and tied together with
metal ties or bonding units to ensure that the
two leaves act as one structural unit, the space
between the leaves being either left as
continuous cavity or filled with a non-load
bearing insulating and water-proofing
material,
b) Faced wall — A wall in which facing and
backing of two different materials are bonded
together to ensure common action under load
{see Fig. 3).
NATIONAL BUILDING CODE OF INDIA
CONCRETE BACKING
BRICK BACKING ^ S TONE FACING
STONE FACING
BRICK
FACING
CONCRETE BLOCK
BACKING
4-^-
Fig. 3 Typical Faced Wall
NOTE — To ensure monolithic action in faced walls,
shear strength between the facing and the backing shall
be provided by toothing, bonding or other means.
c) Veneered wall — A wall in which the facing
is attached to the backing but not so bonded
as to result in a common action under load.
3 MATERIALS
3.1 General
The materials used in masonry construction shall be
in accordance with Part 5 'Building Materials'.
3.2 Masonry Units
Masonry units used in construction shall conform to
accepted standards [6-4(1)].
3.2.1 Masonry units may be of the following types:
a) Common burnt clay building bricks,
b) Burnt clay fly ash building bricks,
c) Pulverized fuel ash lime bricks,
d) Stones (in regular sized units),
e) Sand-lime bricks,
f) Concrete blocks (solid and hollow),
g) Lime based blocks,
h) Burnt clay hollow blocks,
j) Gypsum partition blocks,
k) Autoclaved cellular concrete blocks, and
m) Concrete stone masonry blocks.
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
NOTES
1 Gypsum partition blocks are used only for
construction of non-load bearing partition walls.
2 Use of other masonry units, such as, precise stone
blocks, fly-ash-lime- gypsum bricks, stabilized mud blocks
and other bricks/blocks not covered by the above
specifications may also be permitted based on test results.
3.2.2 Masonry units that have been previously used
shall not be re-used in brickwork or blockwork
construction, unless they have been thoroughly cleaned
and conform to this Section for similar new masonry
units.
3.3 Mortar
Mortar for masonry shall conform to accepted standard
[6-4(2)1.
3.3.1 Mix proportions and compressive strengths of
some of the commonly used mortars are given in
Table 1.
Table 1 Mix Proportions and Strength of Mortars for Masonry
(Clause 3.3.1)
SI
Grade of
Mix Proportions (by Loose Volume)
Minimum Compressive
No.
Mortar
^-*v_
Strength at 28 Days
in N/mm 2
Cement
Lime
Lime Pozzolana
Pozzolana
Sand
Mixture
(1)
(2)
(3)
(4)
(5)
(6)
(7) '
(8)
1
HI
1
Va C or B
3
10
2(a)
H2
1
V4 C or B
4
7.5
2(b)
1
Vi C or B
414
6.0
3(a)
Ml
1
5
5.0
3(b)
1
ICorB
6
3.0
3(c)
1 (LP-40)
Vh
3.0
4(a)
M2
1
6
3.0
4(b)
1
2B
9
2.0
4(c)
1 A
2
2.0
4(d)
IB
1
1
2.0
4(e)
1 C or B
2
2.0
4(f)
1 (LP-40)
1%
2.0
5(a)
M3
1
7
1.5
5(b)
1
3B
12
1.5
5(c)
1 A
3
1.5
5(d)
1 B
2
1
1.5
5(e)
1 C or B
3
1.5
5(f)
1 (LP-40)
2
1.5
6(a)
LI
1
8
0.7
6(b)
IB
1
2
0.7
6(c)
ICorB
2
1
0.7
6(d)
1 (LP-40)
2Va
0.7
6(e)
1 (LP-20)
Wi
0.7
7(a)
L2
IB
3
0.5
7(b)
ICorB
1
2
0.5
7(c)
1 (LP-7)
IV2
0.5
NOTES
1 Sand for making mortar should be well graded. In case sand is not well graded, its proportion shall be reduced in order to achieve
the minimum specified strength.
2 For mixes in SI No. 1 and 2, use of lime is not essential from consideration of strength as it does not result in increase in strength.
However, its use is highly recommended since it improves workability.
3 For mixes in SI No. 3(a), 4(a), 5(a) and 6(a), either lime C or B to the extent of Vi part of cement (by volume) or some plasticizer
should be added for improving workability.
4 For mixes in SI No. 4(b) and 5(b), lime and sand should first be ground in mortar mill and then cement added to coarse stuff.
5 It is essential that mixes in SI No. 4(c), 4(d), 4(e), 5(d), 5(e), 6(b), 6(c), 7(a) and 7(b) are prepared by grinding in a mortar mill.
6 Mix in SI No. 2(b) has been classified to be of same grade as that of SI No. 2(a), mixes in SI No. 3(b) and 3(c) same as that in
SI No. 3(a), mixes in SI No. 4(b) to 4(f) same as that in SI No. 4(a), even though their compressive strength is less. This is from
consideration of strength of masonry using different mix proportions.
7 A, B and C denote eminently hydraulic lime, semi-hydraulic lime and fat lime respectively, as specified in appropriate standards
listed in Part 5 'Building Materials',
NATIONAL BUILDING CODE OF INDIA
4 DESIGN CONSIDERATIONS
4.1 General
Masonry structures gain stability from the support
offered by cross walls, floors, roof and other elements,
such as, piers and buttresses. Load bearing walls are
structurally more efficient when the load is uniformly
distributed and the structure is so planned that
eccentricity of loading on the members is as small as
possible. Avoidance of eccentric loading by providing
adequate bearing of floor/roof on the walls providing
adequate stiffness in slabs and avoiding fixity at the
supports, etc, is especially important in load bearing
walls in multi-storey structures. These matters should
receive careful consideration during the planning stage
of masonry structures.
4.2 Lateral Supports and Stability
4.2.1 Lateral Supports
Lateral supports for a masonry element, such as, load
bearing wall or column are intended:
a) to limit slenderness of a masonry element so
as to prevent or reduce possibility of buckling
of the member due to vertical loads; and
b) to resist horizontal components of forces so
as to ensure stability of a structure against
overturning.
4.2.1.1 Lateral support may be in the vertical or
horizontal direction, the former consisting of floor/roof
bearing on the wall or properly anchored to the same
and latter consisting of cross walls, piers or buttresses.
4.2.1.2 Requirements of 4.2.1(a) from consideration of
slenderness may be deemed to have been met with, if:
a)
In case of a wall, where slenderness ratio is
based on effective height, any of the following
constructions are provided:
1 ) RCC floor/roof slab (or beams and slab)
irrespective of the direction of span, bears
on the supported wall as well as cross
walls, to the extent of at least 90 mm;
RCC floor/roof slab not bearing on the
supported wall or cross wall is anchored
to it with non-corrodible metal ties of
600 mm length and of section not less
than 6 mm x 30 mm, and at intervals not
exceeding 2 m, as shown in Fig. 4; and
50 mm
2)
A = Cement concrete only at places where anchors are
provided (200 mm in width in the direction
perpendicular to the plane of paper)
Fig. 4 Anchoring of RCC Slab with Masonry
Wall (when Slab does not Bear on Wall)
3) Timber floor/roof, anchored by non-
corrodible metal ties of length 600 mm
and of minimum section 6 mm x 30 mm,
securely fastened to joists and built into
walls as shown in Fig. 5 and Fig. 6. The
CONCRETE, min
LENGTH 300 mm
METAL ANCHOR 600 mm
LONG, FIXED TO JOIST
CONCRETE, min.
LENGTH 300 mm
-METAL ANCHOR 600 mrrf
LONG, FIXED TO JOIST
5A JOISTS AT RIGHT ANGLE TO WALL 5B JOISTS PARALLEL TO WALL
Fig. 5 Typical Details for Anchorage of Solid Walls
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
CONCRETE, min. LENGTH 300 mm
METAL ANCHOR FIXED TO JOIST
(i)
6 A TIMBER JOISTS AT RIGHT ANGLES TO WALL
(")
ff Am it t.n tiiri\f a
CONCRETE PAD TO SUIT
BRICK COURSES
-/7!V <i i cJJL
j j j j j jifiii j i j j fsif, i , ~Ja
METAL ANCHOR
FIXED TO JOIST
(i)
A
V.
V 7yTv
MILD STEEL DOWEL
6 B TIMBER JOISTS PARELLEL TO WALL
TOPPING
as III?! 1 1 ti u
CO
^ l yj p n i | ^
0)
-METAL ANCHOR TURNED DOWN
BETWEEN CONCRETE UNITS
6 C PRECAST CONCRETE FLOOR UNITS PARALLEL TO WALL
Fig. 6 Typical Details for Anchorage of Cavity Walls
10
NATIONAL BUILDING CODE OF INDIA
b)
anchors shall be provided in the direction
of span of timber joists as well as in its
perpendicular direction, at intervals of
not more than 2 m in buildings up to two
storeys and 1.25 m for buildings more
than two storeys in height.
NOTES
1 In case precast RCC units are used for floors
and roofs, it is necessary to interconnect them and
suitably anchor them to the cross walls so that
they can transfer lateral forces to the cross walls.
2 In case of small houses of conventional designs,
not exceeding two storeys in height, stiffening
effect of partitions and cross walls is such that
metal anchors are normally not necessary in case
of timber floor/roof and precast RCC floor/roof
units.
In case of a wall, when slenderness ratio
is based on its effective length; a cross
wall/pier/buttress of thickness equal to or
more than half the thickness of the
supported wall or 90 mm, whichever is
more, and length equal to or more than
one-fifth of the height of wall, is built at
right angle to the wall {see Fig. 7) and
bonded to it according to provision
of 4.2.2.2(d);
1/5 HEIGHT OF WALL
W2 OR 90 mm
WHICHEVER
IS GREATER
Fig. 7 Minimum Dimension for Masonry Wall
or Buttress Effective Lateral Support
c) In case of a column, an RCC or timber
beam/R S joist/roof truss, is supported on
the column. In this case, the column will
not be deemed to be laterally supported
in the direction at right angle to it; and
d) In case of a column, an RCC beam
forming a part of beam and slab
construction, is supported on the column,
and slab adequately bears on stiffening
walls. This construction will provide
lateral support to the column, in the
direction of both horizontal axes.
4.2.2 Stability
A wall or column subject to vertical and lateral loads
may be considered to be provided with adequate lateral
support from consideration of stability, if the
construction providing the support is capable of
resisting some of the following forces:
a) Simple static reactions at the point of lateral
support to all the lateral loads; plus
b) 2.5 percent of the total vertical load that the
wall or column is designed to carry at the point
of lateral support.
4.2.2.1 For the purpose specified in 4.2.2, if the lateral
supports are in the vertical direction, these should meet
the requirements given in 4.2.1.2(a) and should also
be capable of acting as horizontal girders duly anchored
to the cross wall so as to transmit the lateral loads to
the foundations without exceeding the permissible
stresses in the cross walls.
4.2.2.2 In case of load bearing buildings up to four
storeys, stability requirements of 4.2.2 may be deemed
to have been met with, if:
a)
b)
c)
height to width ratio of building does not
exceed 2;
cross walls acting as stiffening walls
continuous from outer wall to outer wall or
outer wall to a load bearing inner wall, and of
thickness and spacings as given in Table 2
are provided. If stiffening wall or walls that
are in a line, are interrupted by openings,
length of solid wall or walls in the zone of
the wall that is to be stiffened shall be at least
one-fifth of height of the opening as shown
in Fig. 8;
floors and roof either bear on cross walls or
are anchored to those walls as in 4.2.1.2 such
that all lateral loads are safely transmitted
to those walls and through them to the
foundation; and
Table 2 Thickness and Spacing of
Stiffening Walls
[Clause 4.2.2.2(b)]
SI
No.
Thickness
of Load
Bearing
Wall to be
Stiffened
Height 1 *
of Storey
Not to
Exceed
Stiffening Wall 1 *
**-
Thickness not
less than
Maximum
Spacing
lto3
4 to 6
mm
m
storeys
mm
storeys
mm
m
(1)
(2)
(3)
(4)
(5)
(6)
i)
100
3.2
100
—
4.5
ii)
200
3.2
100
200
6.0
iii)
300
3.4
100
200
8,0
iv)
Above 300
5.0 100
rid maximum spacings
as.
200
as given
8
l) Storey height ai
centre dimensio
are centre-to-
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
11
;. - ' • !" — , ' " i M "
^
STIFFENING
WALL
OPENING
&£
P
i
H/5
OPENING
Fig. 8 Opening in Stiffening Wall
d) cross walls are built jointly with the bearing
walls and are jointly mortared, or the two
interconnected by toothing. Alternatively,
cross walls may be anchored to walls to be
supported by ties of non-corrodible metal of
minimum section 6 mm x 35 mm and length
600 mm with ends bend at least 50 mm;
maximum vertical spacing of ties being 1 .2 m
(see Fig. 9).
Fig. 9 Anchoring of Stiffening Wall with
Support Wall
4.2.2.3 In case of halls exceeding 8.0 m in length,
safety and adequacy of lateral supports shall always
be checked by structural analysis.
4.2.2.4 A trussed roofing may not provide lateral
support unless special measures are adopted to brace
and anchor the roofing. However, in case of residential
and similar buildings of conventional design with
trussed roofing having cross walls, it may be assumed
that stability requirements are met with by the cross
walls and structural analysis for stability may be
dispensed with.
4.2.2.5 Capacity of a cross wall, also called shear wall,
sometimes to take horizontal loads and consequently
bending moments increases, when parts of bearing
walls act as flanges to the cross wall. Maximum
overhanging length of bearing wall which could
effectively function as a flange should be taken as 12 t
or ///6, whichever is less in case of 77/ shaped walls,
and 6 1 or Hi\ 6, whichever is less in case of LIU shaped
walls, where t is the thickness of bearing wall and H is
the total height of wall above the level being
considered, as shown in Fig. 10.
4.2.2.6 External walls of basement and plinth
In case of external walls of basement and plinth,
stability requirements of 4.2.2 may be deemed to have
been met with, if:
a) bricks used in basement and plinth have a
minimum crushing strength of 5 N/mm 2 and
mortar used in masonry is of Grade Ml or
better;
b) clear height of ceiling in basement does not
exceed 2.6 m;
c) walls are stiffened according to provisions
of 4.2.2.1;
d) in the zone of action of soil pressure on
basement walls, traffic load excluding any
surcharge due to adjoining buildings does not
exceed 5 kN/m 2 and terrain does not rise; and
e) minimum thickness of basement walls is in
accordance with Table 3.
NOTE — In case there is surcharge on basement walls
from adjoining buildings, thickness of basement walls
shall be based on structural analysis.
Table 3 Minimum Thickness of Basement Walls
[Clause 4.2.2.6(e)]
SI
No.
Height of the Ground Above
Basement Floor Level
-*-
Minimum
Nominal
Thickness
of
Basement
(4)
(1)
Wall loading
(permanent load)
less than 50 kN/m
(2)
Wall loading
(permanent load)
more than 50 kN/m
(3)
i)
ii)
Up to 1.4 m
Up to 2 m
\fy to 1.75 m
Up to 2.5 m
300 mm
400 mm
4.2.2.7 Walls mainly subjected to lateral loads
a) Free standing wall — A free standing wall
such as compound wall or parapet wall is
acted upon by wind force which tends to
overturn it. This tendency to over-turning is
resisted by gravity force due to self-weight
of wall, and also by flexural moment of
resistance on account of tensile strength of
12
NATIONAL BUILDING CODE OF INDIA
t—>
T^mZZZZZZZZ
t— '
gZ'TTWZZZ
■b l
KZ
Z2
EFFECTIVE OVERHANGING WIDTH
OF FLANGE = 12 t OR H/6 WHICHEVER
IS LESS, H BEING THE TOTAL HEIGHT
OF WALL ABOVE THE LEVEL BEING
CONSIDERED
EFFECTIVE OVERHANGING
WIDTH OF FLANGE, BOTH SIDES
EFFECTIVE OVERHANGING WIDTH
OF FLANGE = 6 t OR H/16 WHICHEVER
IS LESS, H BEING THE TOTAL HEIGHT
OF WALL ABOVE THE LEVEL BEING
CONSIDERED
YW77W?Zm.
X
EFFECTIVE OVERHANGING
WIDTH OF FLANGE
Fig. 10 Typical Details for Anchorage of Solid Walls
b)
masonry. Free standing walls shall thus be
designed as in 5,5.2.1. If mortar used for
masonry cannot be relied upon for taking
flexural tension (see 5.4.2), stability of free
standing wall shall be ensured such that
stability moment of wall due to self- weight
equals or exceeds 1.5 times the overturning
moment.
Retaining wall — Stability for retaining walls
shall normally be achieved through gravity
action but flexural moment of resistance could
also be taken advantage of under special
circumstances at the discretion of the designer
(see 5.4.2).
4.3 Effective Height
4.3.1 Wall
Effective height of a wall shall be taken as shown in
Table 4 (see Fig. 11).
NOTE — A roof truss or beam supported on a column meeting
the requirements of 4.2.2.1 is deemed to provide lateral support
to the column only in the direction of the beam/truss.
4.3.2 Column
In case of a column, effective height shall be taken as
actual height for the direction it is laterally supported
and twice the actual height for the direction it is not
laterally supported (see Fig. 12).
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
13
Table 4 Effective Height of Walls
(Clause 4.3.1)
SI No.
(1)
Condition of Support
(2)
Effective Height
(3)
i) Lateral as well as rotational restraint (that is, fall restraint) at top and bottom. For example, when the floor/roof 0.75 H
spans on the walls so that reaction to load of floor/roof is provided by the walls, or when an RCC floor/roof
has bearing on the wall (minimum 9 cm), irrespective of the direction of the span foundation footings of a wall
give lateral as well as rotational restraint
ii) Lateral as well as rotational restraint (that is, full restraint) at one end and only lateral restraint (that is, partial 0.85 H
restraint) at the other. For example, RCC floor/roof at one end spanning or adequately bearing on the wall and
timber floor/roof not spanning on wall, but adequately anchored to it, on the other end
iii) Lateral restraint, without rotational restraint (that is, partial restraint) on both ends. For example, timber floor/roof, 1 .00 H
not spanning on the wall but adequately anchored to it on both ends of the wall, that is, top and bottom
iv) Lateral restraint as well as rotational restraint (that is, full restraint) at bottom but have no restraint at the top. 1.50 H
For example, parapet walls with RCC roof having adequate bearing on the lower wall, or a compound wall
with proper foundation on the soil.
NOTES
1 H is the height of wall between centres of support in case of RCC slabs and timber floors. In case of footings or foundation block,
height (H) is measured from top of footing or foundation block. In case of roof truss, height (H) is measured up to bottom of the tie
beam. In case of beam and slab construction, height should be measured from centre of bottom slab to centre of top beam. All these
cases are illustrated by means of examples shown in Fig. 1 1 .
2 For working out effective height, it is assumed that concrete DPC, when properly bonded with masonry, does not cause
discontinuity in the wall.
3 Where memberane type damp-proof course or termite shield causes a discontinuity in bond, the effective height of wall may be
taken to be greater of the two values calculated as follows:
a) consider H from top of footing ignoring DPC and take effective height as 0.75 H.
b) consider H from top of DPC and take effective height as 0.85 H,
4 When assessing effective height of walls, floors not adequately anchored to walls shall not be considered as providing lateral
support to such walls.
5 When thickness of a wall bonded to a pier is at least two-thirds of the thickness of the pier measured in the same direction, the wall
and pier may be deemed to act as one structural element.
1 1 A RCC FLOOR/ROOF BEING
ON WALL IRRESPECTIVE
OF DIRECTION OF SPAN
11 B TIMBER FLOOR/ROOF
1 1 C TIMBER FLOOR AND
TRUSSED ROOF
1 1 D FREE STANDING WALL
Fig. 11 Effective Height of Wall
14
NATIONAL BUILDING CODE OF INDIA
3— x
i-"
EFFECTIVE HEIGHT
ABOUT AXIS
X-X=1.0H
Y-Y = 1.0H
12A
-ez:
I-E
3— x
EFFECTIVE HEIGHT
ABOUT AXIS
X-X = 2.0H
Y-Y=1.0H
THE BEAM
ONLY
STIFFENING WALL
12 B
12C
Roof Construction
With precast concrete units
of in- situ concrete floor or
roof
With light deck or similar
roof
Effective Height About Axis
Fig. 12B
X-X=1.0H 2
Y-Y=l.0H l
Y-Y= 1.5//!
(No ties)
X-X=1.0H 2
Y-Y=l.0H l
r-r = 2.o//i
(No ties)
Effective Height About Axis
Fig. 12C
X-X=1.5// 2
Y-Y= 1.0 Hi
X-X=2.0H 2
Y-Y=l.0Hi
Fig. 12 Example of Effective Height of Columns
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
15
NOTES
1 A roof truss or beam supported on a column meeting the
requirements of 4.2.2.1 is deemed to provide lateral support to
the column only in the direction of the beam/truss.
2 When floor or roof consisting of RCC beams and slabs is
supported on columns, the columns would be deemed to be
laterally supported in both directions.
43.3 Openings in Walls
When openings occur in a wall such that masonry
between the openings is by definition a column,
effective height of masonry between the openings shall
be reckoned as follows:
a) When wall has full restraint at the top:
1) Effective height for the direction
perpendicular to plane of wall equals
0.75 H plus 0.25 H v where H is the
distance between supports and H x is the
height of the taller opening; and
2) Effective height for the direction parallel
to the wall equals //, that is, the distance
between the supports.
b) When wall has partial restraint at the top and
bottom:
1) Effective height for the direction
perpendicular to plane of wall equals H
when height of neither opening exceeds
0.5 H and it is equal to2H when height
of any opening exceeds 0.5 H\ and
2) Effective height for the direction parallel
to the plane of the wall equals 2 H.
4.4 Effective Length
Effective length of a wall shall be as given in Table 5.
4.5 Effective Thickness
Effective thickness to be used for calculating
slenderness ratio of a wall or column shall be obtained
as in 4.5.1 to 4.5.5.
4.5.1 For solid walls, faced walls or columns, effective
thickness shall be the actual thickness.
4.5.2 For solid walls adequately bonded into piers,
buttresses, effective thickness for determining
slenderness ratio based on effective height shall be the
actual thickness of wall multiplied by stiffening
coefficient as given in Table 6. No modification in
effective thickness, however, shall be made when
slenderness ratio is to be based on effective length of
walls.
4.5.3 For solid walls or faced walls stiffened by cross
walls, appropriate stiffening coefficient may be
Table 5 Effective Length of Walls
(Clause 4.4)
SI No.
(1)
Conditions of Support (See Fig. 13)
(2)
Effective Length
(3)
i) Where a wall is continuous and is supported by cross wall and there is no opening within a distance of /J/8 ;
from the face of cross wall (see Fig. 13)
0.8X
Where a wall is continuous and is supported by piers/buttresses conforming to 4.2.1.2(b)
ii) Where a wall is supported by a cross wall at one end and continuous with cross wall at other end 0.9 L
or
Where a wall is supported by a pier/buttress at one end and continuous with pier/buttress at other end
conforming to 4.2.1.3(b)
iii) Where a wall is supported at each end by cross wall 1 .0 L
or
Where a wall is supported at each end by a pier/buttress conforming to 4.2.1.2(b)
iv) Where a wall is free at one end and continuous with a pier/buttress at the other end ,•,- 1.5 L
or
Where a wall is free at one end and continuous with a pier/buttress at the other end conforming
to 4.2.1.2(b)
v) Where a wall is free at one end and supported at the other end by a cross wall 2.0 L
or
Where a wall is free at one end and supported at the other end by a pier/buttress conforming to 4.2.1.2(b)
where
L ~ Length of wall from or between centres of cross wall, piers or buttress; and '
H = Actual height of wall between centres of adequate lateral support.
NOTE — In case there is an opening taller than 0.5 H in a wall, ends of the wall at the opening shall be considered as free. Cross
walls shall conform to 4.2.2.1(d).
16
NATIONAL BUILDING CODE OF INDIA
ii
I
x>H/8,y>H/6
/=0.8L
ZZZL
fw
Wall is continuous at both ends and is
supported by cross walls of thickness
fw/2 or 100 mm whichever is more,
length of cross wall is not less than
H/6,opening in wail is not less than
H/8 from cross wall
13 A CASE1
rl
y»»*
y»»»\
a-
I
\ m x m I
r 1
x>H/8,y>H/6
/ = 0.9 L
WTHi
r
1 J^2U
1
xs>H/8,y>H/6
/* *.
Same as case 1 except that one end
of the wall is discontinuous
13B CASE2
Same as case 1 except that wall
is discontinuous on both ends
13 C CASE 3
h
Y//////W///A
x>H/8,y>H/6
/=1.5L
i
FREE
END
One end of the wait is free, other is
supported by a cross wall and is
continuous. There being no opening
within H/8 from cross wall
13 D CASE 4
x<H/8,y>H/6
/ = 2L
Li
Same as case 4 but opening is within
H/8 from cross wall and thus that
end is taken as discontinuous
13 E CASES
ezz&zzzzzzzzk.
T7771
Li
WTHT
9
x<H/8,y>H/6
/* 1,5 L 2
EWd :
zza
13 F CASE 6
This illustration Is wtth an opening
which is within H/8 from cross wall
-rra
x ^
x<H/8
Wall length is between two opening which
are closer than H/8 from cross wails
13 G CASE 7
Fig. 13 Effective Length of Wall
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
17
determined from Table 6 on the assumption that the
cross walls are equivalent to piers of width equal to
the thickness of the cross wall and of thickness equal
to three times the thickness of stiffened wall.
Table 6 Stiffening Coefficient for Walls
Stiffened by Piers, Buttresses or Cross Walls
(Clauses 4.5.2 and 4.5.3)
SI
s p
Stiffening Coefficient
No.
Ratio — L
-A-
t.
t.
•'«
^*
-£- = 1
-*- = 2
_p
3 or more
f-
t
t
*w
(1)
(2)
(3)
(4)
(5)
i)
6
1.0
1.4
2.0
ii)
8
1.0
1.3
1.7
iii)
10
1.0
1.2
1.4
iv)
15
1.0
1.1
1.2
v)
20 or more
1.0
1.0
1.0
where
5 p = Centre-to-centre spacing of the pier or cross wall,
t ~ Thickness of pier as defined in 2.3.2 (see Fig. 1),
f w = Actual thickness of the wall proper (see Fig. 1), and
w p = Width of the pier in the direction of the wall or the actual
thickness of the cross wall.
NOTE — Linear interpolation between the values given in this
table is permissible but not extrapolation outside the limits given.
4.5.4 For cavity walls with both leaves of uniform
thickness throughout, effective thickness shall be taken
as two-thirds of the sum of the actual thickness of the
two leaves.
4.5.5 For cavity walls with one or both leaves
adequately bonded into piers, buttresses or cross walls
at intervals, the effective thickness of the cavity wall
shall be two-thirds of the sum of the effective thickness
of each of the two leaves; the effective thickness of each
leaf being calculated using 4,5.1 or 4.5.2 as appropriate.
4.6 Slenderness Ratio
4.6.1 Walls
For a wall, slenderness ratio shall be effective height
divided by effective thickness or effective length
divided by the effective thickness, whichever is less.
In case of a load bearing wall, slenderness ratio shall
not exceed that given in Table 7.
Table 7 Maximum Slenderness Ratio for a
Load Bearing Wall
(Clause 4.6.1)
Number of
Storeys
Maximum Slenderness Ratio
(1)
Using Portland Cement or
Portland Pozzolana Cement
in Mortar
(2)
Using Lime
Mortar
(3)
Not exceeding 2
Exceeding 2
27
27
20
13
4.6.2 Columns
For a column, slenderness ratio shall be taken to be
the greater of the ratios of effective heights to the
respective effective thickness, in the two principal
directions. Slenderness ratio for a load bearing column
shall not exceed 12.
4.7 Eccentricity
Eccentricity of vertical loading at a particular junction
in a masonry wall shall depend on factors, such as
extent of bearing, magnitude of loads, stiffness of slab
or beam, fixity at the support and constructional details
at junctions. No exact calculations are possible to make
accurate assessment of eccentricity. Extent of
eccentricity under any particular circumstances has,
therefore, to be decided according to the best
judgement of the designer. Some guidelines for
assessment of eccentricity are given in Annex A.
5 STRUCTURAL DESIGN
5.1 General
The building as a whole shall be analyzed by accepted
principles of mechanics to ensure safe and proper
functioning in service of its component parts in relation
to the whole building. All component parts of the
structure shall be capable of sustaining the most adverse
combinations of loads, which the building may be
reasonably expected to be subjected to during and after
construction.
5.2 Design Loads
Loads to be taken into consideration for designing
masonry components of a structure are:
a) dead loads of walls, columns, floors and roofs ;
b) live loads of floors and roof;
c) wind loads on walls and sloping roof; and
d) seismic forces.
NOTE — When a building is subjected to other loads,
such as vibration from railways; machinery, etc, these
should be taken into consideration accordingly to the
best judgement of the designer (see also Part 6 'Structural
Design, Section 1 Loads, Forces and Effects').
5.2.1 The design loads an# other forces to be taken for
the design of masonry structures shall conform to Part 6
' Structural Design, Section 1 Loads, Forces and Effects' .
NOTE — During construction, suitable measures shall be taken
to ensure that masonry is not liable to damage or failure due to
action of wind forces, back filling behind walls or temporary
construction loads.
5.3 Load Dispersion
5.3.1 General
The angle of dispersion of vertical load on walls shall
be taken as not more than 30° from the vertical.
18
NATIONAL BUILDING CODE OF INDIA
5.3.2 Arching Action
Account may also be taken of the arching action of
well-bonded masonry walls supported on lintels and
beams, in accordance with established practice.
Increased axial stresses in the masonry associated with
arching action in this way, shall not exceed the
permissible stresses given in 5.4.
5.3.3 Lintels
Lintels that support masonry construction shall be
designed to carry loads from masonry (allowing for
arching and dispersion), where applicable and loads
received from any other part of the structure. Length
of bearing of lintel at each end shall not be less than
90 mm or one-tenth of the span, whichever is more
and area of the bearing shall be sufficient to ensure
that stresses in the masonry (combination of wall
stresses, stresses due to arching action and bearing
stresses from the lintel) do not exceed the stresses
permitted in 5.4 (see Annex C).
5.4 Permissible Stresses
5.4.1 Permissible Compressive Stress
Permissible compressive stress in masonry shall be
based on value of basic compressive stress (f h ) as given
in Table 8 and multiplying this value by factors known
as stress reduction factor (fc s ), area reduction factor (fc a )
and shape modification factor (k ) as detailed in 5.4.1.1
to 5.4.1.3. Values of basic compressive stress given in
Table 8 take into consideration crushing strength of
masonry unit and grades of mortar and hold good for
values of slenderness ratio not exceeding 6, zero
eccentricity and masonry unit having height to width
ratio (as laid) equal to 0.75 or less.
Alternatively, basic compressive stress may be based
on results of prism test given in Annex B on masonry
made from masonry units and mortar to be actually
used in a particular job.
5.4.1.1 Stress reduction factor
This factor, as given in Table 9, takes into consideration
the slenderness ratio of the element and also the
eccentricity of loading.
5.4.1.2 Area reduction factor
This factor takes into consideration smallness of the
sectional area of the element and is applicable when
sectional area of the element is less than 0.2 m 2 .
The factor fc a =0.7+1 .5A, A being the area of section
inm 2 .
5.4.1.3 Shape modification factor
This factor takes into consideration the shape of the
unit, that is, height to width ratio (as laid) and is given
in Table 10. This factor is applicable for units for
crushing strength up to 15 N/mm 2 .
Table 8 Basic Compressive Stresses for Masonry (After 28 days)
(Clauses 5.4.1 and 6.3.1)
SI
No.
Mortar
Type
(Ref Table 1)
Basic Compressive Stresses in N/mm 2 Corresponding to Masonry Units of which Height to Width
Ratio does not Exceed 0.75 and Crushing Strength, in N/mm 2 , is not Less than
3.5
5.0
7.5
10
12.5
15
17.5
20
25
30
35
40
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(H)
(12)
(13)
(14)
i)
HI
0.35
0.50
0.75
1.00
1.16
1.31
1.45
1.59
1.91
2.21
2.5
3.05
ii)
H2
0.35
0.50
0.74
0.96
1.09
1.19
1.30
1.41
1.62
1.85
2.1
2.5
iii)
Ml
0.35
0.50
0.74
0.96
1.06
1.13
1.20
1.27
1.47
1.69
1.9
2.2
iv)
M2
0.35
0.44
0.59
0.81
0.94
1.03
1.10
1.17
1.34
1.51
1.65
1.9
v)
M3
0.25
0.41
0.56
0.75
0.87
0.95
1.02
1.10
1.25
1.41
1.55
1.78
vi)
LI
0.25
0.36
0.53
0.67
0.76
0.83
0.90
0.97
1.11
1.26
1.4
1.06
vii)
L2
0.25
0.31
0.42
0.53
0.58
0.61
0.65
0.69
0.73
0.78
0.85
0.95
NOTES
1 The table is valid for slenderness ratio up to 6 and loading with zero eccentricity.
2 The values given for basic compressive stress are applicable only when the masonry is properly cured.
3 Linear interpolation is permissible for units having crushing strengths between those given in the table.
4 The permissible stress for random rubble masonry may be taken as 75 percent of the corresponding stress for coarsed walling of
similar materials.
5 The strength of ashlar masonry (natural stone masonry of massive type with thin joints) is closely related to intrinsic strength of the
stone and allowable working stress in excess of those given in the table may be allowed for such masonry at the discretion of the
designer.
6 For calculation of basic compressive stress of stabilized mud block having thickness 100 mm or more, reference to specialist
literature may be made.
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
19
Table 9 Stress Reduction Factor for Slenderness Ratio and Eccentricity
(Clause 5 AAA)
Slenderness
Ratio
Eccentricity of Loading Divided by the Thickness of the Member
1/24
1/12
1/6
1/4
1/3
(i)
(2)
(3)
(4)
(5)
(6)
(7)
6
1.00
1.00
1.00
1.00
1.00
1.00
8
0.95
0.95
0.94
0.93
(X92
0.91
10
0.89
0.88
0.87
0.85
0.83
0.81
12
0.84
0.83
0.81
0.78
0.75
0.72
14
0.78
0.76
0.74
0.70
0.66
0.66
16
0.73
0.71
0.68
0.63
0.58
0.53
18
0.67
0.64
0.61
0.55
0.49
0.43
20
0.62
0.59
0.55
0.48
0.41
0.34
22
0.56
0.52
0.48
0.40
0.32
0.24
24
0.51
0.47
0.42
0.33
0.24
—
26
0=45
0.40
0.35
0.25
—
—
27
0.43
0.38
0.33
0.22
—
—
NOTES
1 Linear interpolation between values is permitted.
2 Where in special cases the eccentricity of loading lies between 1/3 and 1/2 of the thickness of the member, the stress reduction
factor should vary linearly between unity and 0.20 for slenderness ratio of 6 and 20 respectively.
3 Slenderness ratio of a member for sections within 1/8 of the height of the member above or below a lateral support may be taken to
be 6.
Table 10 Shape Moditlcation Factor
for Masonry Units
(Clause 5.4.1.3)
Height to
Width Ratio
of Units
(as Laid)
(1)
Shape Modification Factor (k p ) for Units
Having Crushing Strength in N/mm 2 is
5.0
(2)
7.5
(3)
10.0
(4)
15.0
(5)
Up to 0.75
1.0
1.5
2.0 to 4.0
1.0
1.2
1.5
1.8
1.0
1.1
1.3
1.5
1.0
1.1
1.2
1.3
1.0
1.0
1.1
1.2
NOTE — Linear interpolation between values is permissible.
5.4.1.4 Increase in permissible compressive stresses
allowed for eccentric vertical loads, lateral loads under
certain conditions
In members subjected to eccentric and/or lateral loads,
increase in permissible compressive stress is allowed
as follows:
a) When resultant eccentricity ratio exceeds
1/24 but does not exceed 1/6, 25 percent
increase in permissible compressive stress is
allowed in design.
b) When resultant eccentricity ratio exceeds
1/6, 25 percent increase in permissible stress
is allowed but the area of the section under
tension shall be disregarded for computing the
load carrying capacity of the member.
NOTE — When resultant eccentricity ratio of loading is
1/24 or less, compressive stress due to bending shall be
ignored and only axial stress need be computed for the
purpose of design.
5,4. 1.5 Increase in permissible compressive stress for
walls subjected to concentrated loads
When a wall is subjected to a concentrated load (a load
being taken to be concentrated when area of supporting
wall equals or exceeds three times the bearing area),
certain increase in permissible compressive stress may
be allowed because of dispersal of the load. Since,
according to the present state of art, there is diversity
of views in regard to manner and extent of dispersal,
design of walls subjected to concentrated loads may,
therefore, be worked out as per the best judgement of
the designer. Some guidelines in this regard are given
in Annex C.
5.4.2 Permissible Tensile Stress
As a general rule, design of masonry shall be based on
the assumption that masonry is not capable of taking
any tension. However, in case of lateral loads normal
to the plane of wall, which causes flexural tensile stress,
as for example, panel, curtain partition and free
standing walls, flexural tensile stresses as follows may
be permitted in the design for masonry:
20
NATIONAL BUILDING CODE OF INDIA
Grade Ml or - 0.07 N/mm 2 for bending in
better mortar the vertical direction where
tension developed is normal
to bed joints.
- 0.14 N/mm 2 for bending in
the longitudinal direction
where tension developed
is parallel to bed joints,
provided crushing strength
of masonry units is not less
than 10 N/mm 2 .
Grade M2 mortar - 0.05 N/mm 2 for bending in
the vertical direction where
tension developed is normal
to bed joints.
- 0.10 N/mm 2 for bending in
the longitudinal direction
where tension developed
is parallel to bed joints,
provided crushing strength
of masonry units is not less
than 7.5 N/mm 2 .
NOTES
1 No tensile stress is permitted in masonry in case of water-
retaining structures in view of water in contact with masonry.
Also no tensile stress is permitted in earth-retaining
structures, in view of the possibility of presence of water at
the back of such walls.
2 Allowable tensile stress in bending in the vertical direction
may be increased to 0.1 N/mm 2 for Ml mortar and 0.07 N/mm 2
for M2 mortar in case of boundry walls/compound at the
discretion of the designer, since there is not much risk to life
and property in the event of failure of such walls.
5.4.3 Permissible Shear Stress
In case of walls built in mortar not leaner than Grade
Ml (see Table 1) and resisting horizontal forces in the
plane of the wall, permissible shear stress calculated
on the area of bed joints, shall not exceed the value
obtained by the formula given below, subject to a
maximum of 0.5 N/mm 2 :
/. = 0.1 + / d /6
/ = Compressive stress due to dead loads in
/.
N/mm 2 , and
Permissible shear stress in N/mm 2 .
5.4.4 If there is tension in any part of a section of
masonry, the area under tension shall be ignored while
working out shear stress on the section.
5.5 Design Thickness/Cross-Section
5.5.1 Walls and Columns Subjected to Vertical Loads
Walls and columns bearing vertical loads shall be
designed on the basis of permissible compressive stress.
Design consists in determining thickness in case of
walls and section in case of columns in relation to
strength of masonry units and grade of mortar to be
used, taking into consideration various factors, such
as slenderness ratio, eccentricity, area of section,
workmanship, quality of supervision, etc, subject
further to provisions of 5.5.1.1 to 5.5.1.4.
5.5.1.1 Solid walls
Thickness used for design calculation shall be the actual
thickness of masonry computed as the sum of the
average dimensions of the masonry units specified in
the relevant standard, together with the specified joint
thickness. In masonry with raked joints, thickness shall
be reduced by the depth of raking, of joints for
plastering/pointing.
5.5.1.2 Cavity walls
a) Thickness of each leaf of a cavity wall shall
not be less than 15 mm.
b) Where the outer leaf is half masonry unit in
thickness, the uninterrupted height and length
of this leaf shall be limited so as to avoid
undue loosening of ties due to differential
movements between the two leaves. The outer
leaf shall, therefore, be supported at least at
every third storey or at every 10 m of height
whichever is less, and at every 10 m or less
along the length.
c) Where the load is carried by both leaves of a
wall of a cavity construction, the permissible
stress shall be based on the slenderness ratio
derived from the effective thickness of
the wall as given in 4.5.4 or 4.5.5. The
eccentricity of the load shall be considered
with respect to the centre of gravity of the
cross-section of the wall.
d) Where the load is carried by one leaf only,
the permissible stress shall be the greater of
values calculated by the following two
alternative methods:
1) The slenderness ratio is based on the
effective thickness of the cavity wall as
a whole as given in 4.5.4 or 4.5.5 and on
the eccentricity of the load with respect
to the centre of gravity of the cross-
section of the whole wall (both leaves).
(This is the same method as where the
load is carried by both the leaves but the
eccentricity will be more when the load
is carried by one leaf only.)
2) The slenderness ratio is based on the
effective thickness of the loaded leaf only
using 4.5.1 and 4.5.2, and the eccentricity
of the load will also be with respect to the
centre of gravity of the loaded leaf only.
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
21
In either alternative, only the actual thickness of the
load bearing leaf shall be used in arriving at the cross-
sectional area resisting the load (see 5.5,1. 1).
5.5.1.3 Faced wall
The permissible load per length of wall shall be taken
iic thf r\rr\rhir't rvf tV»^ tr\tc*1 thir>Vn**ee r\f i\\(* Ai7all anrl tV>*a
«., «* v r v«„v t w uiv tVt t*x unvivi^^ v^ i±i^ yy**j.i "»" ««*
permissible stress in the weaker of the two materials.
The permissible stress shall be found by using the total
thickness of the wall when calculating the slenderness
ratio.
Table 11 Height to Thickness Ratio of Free
Standing Walls Related to Wind Speed
(Clause 5.5.2.1)
Design Wind Pressure
Height to Thickness Ratio
N/mm 2
(1)
(2)
Up to 285
575
860
1 150
10
7
5
4
5.5.1.4 Veneered wall
The facing (veneer) shall be entirely ignored in
calculations of stren CT th and stability. For the "un^ose
of determining the permissible stress in the backing,
the slenderness ratio shall be based on the thickness of
the backing alone.
5,5.2 ^^alls aV^ (~*nliiVYtr\ c ~\Artiv%1~\i ^iihtiant*?/! tn J rtiarrtl
Loads
C C ^ 1 T? ^ ___ JJ 77 _
*?.^.^.i r tee siunaing wuus
a) Free standing walls, subjected to wind
pressure or seismic forces shall be designed
on tnc uasis Oi permissiuie tensne stress in
rrmsnnrv or ctaWilitv aQ in 4.7 7.4 T-Trm/^vfn*
j ^ ^ „„_, „ — „ .._.— .. ** v , Iv . Vi ,
in seismic Zones II, free-standing walls may
be apportioned without making any design
calculations with the help of Table 11
provided the mortar used is of grade not leaner
than Ml.
b) If there is a horizontal damp-proof course near
i.ij.v-' uuljv wx \.xi\s vy uxx, umi j.^, xxvsi ^upauiv \ji.
develooine tension verticallv. the minimum
wall thickness should be the greater of that
calculated from either:
1) the appropriate height to thickness ratio
given in Table 1 1 reduced by 25 percent,
reckoning the height from the level of the
damp-proof course; or
tnc appropriate ueigut to tniCKness ratio
oivpn in TnKI*» 1 1 r^r^VonincT the
£,*. » VJ.M. ±tl J. UUJ.W J. J. l.VVXVV/lUU.il V11V
h(*\crht
from the lower level at which the wall is
restrained laterally.
Normally masonry of retaining walls shall be designed
on the basis of zero-tension, and permissible
compressive stress. However in case of retaining walls
for supporting horizontal thrust from dry materials,
retaining walls may be designed on the basis of
permissible tensile stress at the discretion of the
designers.
1 For intermediate values, linear interpolation is permissible.
2 Height is to be reckoned from 150 mm below ground level
or top of footing/foundation block, whichever is higher, and
nn to thf*. ton eAve. of the wall
3 The thickness should be measured including the thickness
of the plaster.
C C 1 XMnUo „** A n nil. *>»*** Qi.Ul^^+rtsI +^ T/yj*-*;^/ /inu»/)//
as Lateral Loads
± wi wans uuu ^uiuiiuii}, lJlxvlJlJ vfuiivuu wui oupai clival y
for vertical loads as in 5,5,1 and lateral loads as in 5,5,2
shall be combined and elements designed on the basis
of permissible stress.
5.5.4 Walls Subjected to In-Plane Bending and
Vertical Loads (Shear Walls)
Walls subjected to in-plane bending and vertical loads,
that is, shear walls shall be designed on the basis of no
tension with permissible shear stress and permissible
compressive stress.
5.5.5 Non-Load Bearing Walls
Non-load bearing walls, such as panel walls, curtain
walls and partition walls which are mainly subjected to
lateral loads, according to present state of art, are not
capable of precise design and only approximate methods
noporl r\r\ rrttno toctc oro oi/oilonlfl iTiiinflliTKip Tr\f
l/ujvu \jh ouiiiv ivoio uiv u. y uimuiv, vjuiuvniiva ±\ji
approximate design of these walls are given in Annex D.
6 GENERAL REQUIREMENTS
6.1 Methods of Construction
6.1.1 General
Construction of the following tvnes of load bearing
and non-load bearing masonry walls shall be carried
out in accordance with good practice [6-4(3)].
a) Brickwork,
b) Stone masonry,
c) Hollow concrete block masonry,
d) Gypsum partition blocks,
e) Autoclaved cellular concrete block masonry,
and
f) Lightweight concrete block masonry.
r^AllVAI^IAlj DUlLiUliUVT \^KJUlL \jr LT*U1J\
6.1.2 Construction of Buildings in Seismic Zones
No special provisions on construction are necessary
for buildings constructed in Zones II. Special features
of construction for earthquake resistant masonry
buildings in Zones III, IV and V shall be applicable
according to good practice [6-4(3)].
6.2 Minimum Thickness of Walls from Consideration
other than Structural
Thickness of walls determined from consideration of
strength and stability may not always be adequate in
respect of other requirements, such as resistance to
fire, thermal insulation, sound insulation and
resistance to damp penetration for which reference
may be made to the appropriate Parts/Sections of the
Code, and thickness suitably increased, where found
necessary.
6.3 Workmanship
6.3.1 General
Workmanship has considerable effect on strength of
masonry and bad workmanship may reduce the strength
of brick masonry to as low as half the intended strength.
The basic compressive stress values for masonry as
given in Table 8 would hold good for commercially
obtainable standards of workmanship with reasonable
degree of supervision. If the work is inadequately
supervised, strength should be reduced to three-fourth
or less at the discretion of the designer.
6.3.2 Bedding of Masonry Units
Masonry units shall be laid on a full bed of mortar
with frog, if any, upward such that cross-joints and
wall joints are completely filled with mortar. Masonry
units which are moved after initial placement shall
be relaid in fresh mortar, discarding the disturbed
mortar.
6.3.3 Bond
Cross-joints in any course of one brick thick masonry
wall shall be not less than one-fourth of a masonry
unit in horizontal direction from the cross-joints in the
course below. In masonry walls more than one brick
in thickness, bonding through the thickness of wall
shall be provided by either header units or by other
equivalent means in accordance with good practice
[6-4(4)].
6.3.4 Verticality and Alignment
All masonry shall be built true and plumb within the
tolerances prescribed below; care shall be taken to keep
the perpends properly aligned:
a) Deviation from vertical within a storey shall
not exceed 6 mm per 3 m height.
b) Deviation in verticality in total height of any
wall of a building more than one storey in
height shall not exceed 12.5 mm.
c) Deviation from position shown on plan of any
brickwork shall not exceed 12.5 mm.
d) Relative displacement between load bearing
walls in adjacent storeys intended to be in
vertical alignment shall not exceed 6 mm.
e) Deviation of bed-joint from horizontal in a
length of 12 m shall not exceed 6 mm subject
to a maximum deviation of 12 mm.
f) Deviation from the specified thickness of bed
joints, cross-joints and perpends shall not
exceed one-fifth of the specified thickness.
NOTE — These tolerances have been specified from
the point of view of their effect on the strength of
masonry. The permissible stress recommended in 5.3
may be considered applicable only if these tolerances
are adhered to,
6.4 Joints to Control Deformation and Cracking
Special provision shall be made to control or isolate
thermal and other movements so that damage to the
fabric of the building is avoided and its structural
sufficiency preserved. Design and installation of
joints shall be done according to the appropriate
recommendations in accordance with good practice
[6-4(5)].
6.5 Chases, Recesses and Holes
6.5.1 Chases, recesses and holes are permissible in
masonry only if these do not impair strength and
stability of the structure.
6.5.2 In masonry, designed by structural analysis, all
chases, recesses and holes shall be considered in
structural design and detailed in building plans.
6.5.3 When chases, recesses and holes have not been
considered in structural design and are not shown in
drawings, these may be provided, subject to the
constraints and precautions specified in 6.5.3.1
to 6.5.3.10.
6.5.3.1 As far as possible, services should be planned
with the help of vertical chases and use of horizontal
chases should be avoided.
6.5.3.2 For load bearing walls, depth of vertical and
horizontal chases shall not exceed one-third and one-
sixth of the wall thickness respectively.
6.5.3.3 Vertical chases shall not be closer than 2 m in
any stretch of wall and shall not be located within
345 mm of an opening or within 230 mm of a cross
wall that serves as a stiffening wall for stability. Width
of a vertical chase shall not exceed thickness of wall
in which it occurs.
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
23
6.5.3.4 When unavoidable horizontal chases of width
not exceeding 60 mm in a wall having slenderness
ratio not exceeding 15 may be provided. These shall
be located in the upper or lower middle third height
of wall at a distance not less than 600 mm from a
lateral support. No horizontal chase shall exceed
1 m in length and there shall not be more than
2 chases in any one wall. Horizontal chases shall have
minimum mutual separation distance of 500 mm. Sum
of lengths of all chases and recesses in any horizontal
plane shall not exceed one-fourth the length of the
wall.
6.5.3.5 Holes for supporting put-logs of scaffolding
shall be kept away from bearings of beams, lintels,
and other concentrated loads. If unavoidable, stresses
in the affected area shall be checked to ensure that these
are within safe limits.
6.5.3.6 No chase, recess or hole shall be provided in
any stretch of a masonry wall, the length of which is
less than four times the thickness of wall, except when
found safe by structural analysis.
6.5.3.7 Masonry directly above a recess or a hole, if
wider than 300 mm, shall be supported on a lintel. No
lintel, however, is necessary in case of a circular recess
or hole exceeding 300 mm in diameter provided upper
half of the recess or hole is built as a semi-circular
arch of adequate thickness and there is a adequate
length of masonry on the sides of openings to resist
the horizontal thrust.
6.5.3.8 As far as possible chases, recesses and holes
in masonry should be left (inserting sleeves, where
necessary) at the time of construction of masonry so
as to obviate subsequent cutting. If cutting is
unavoidable, it should be done without damage to the
surrounding or residual masonry. It is desirable to use
such tools for cutting which depend upon rotary and
not on heavy impact for cutting action.
6.5.3.9 No chase, recess or hole shall be provided in
half-brick load bearing wall, excepting the minimum
number of holes needed for scaffolding.
6.5.3.10 Chases, recesses or holes shall not be cut into
walls made of hollow or perforated units, after the units
have been incorporated in masonry.
6.6 Corbelling
6.6.1 Where corbelling is required for the support
of some structural element, maximum projection of
masonry unit should not exceed one-half of the
height of the unit or one-half of the built-in part of
the unit and the maximum horizontal projection of
the corbel should not exceed one-third of the wall
thickness.
6.6.2 The load per unit length on a corbel shall not
be greater than half of the load per unit length on the
wall above the corbel. The load on the wall above
the corbel, together with four times the load on the
corbel, shall not cause the average stress in the
supporting wall or leaf to exceed the permissible
stresses given in 5.4.
6.6.3 It is preferable to adopt header courses in the
corbelled portion of masonry from considerations of
economy and stability.
7 SPECIAL CONSIDERATION IN
EARTHQUAKE ZONES
7.0 Special features of design and construction for
earthquake resistant masonry buildings are given in 7.2
to 7.8.2. Reference may also be made to good practice
[6-4(6)] for detailed information.
7.1 Categories of Buildings
For the purpose of specifying the earthquake resistant
features in masonry and wooden buildings, the
buildings have been categorized in five categories A
to E based on the seismic zone and the importance of
building /,
where
/ = Importance factor applicable to the building
(see Table 35 of Part 6, Section 1)
7.1.1 The building categories are given in Table 12.
Table 12 Building Categories for Earthquake
Resisting Features
(Clauses 1.1.1 and % A 2)
Importance Factor
Seismic Zone
m
IV
(1)
(2)
(3)
(4)
(5)
1.0
A
B
C
D
1.5
B
C
D
E
7.2 Masonry Units
Bricks/Blocks as per the accepted standards [6-4(1)]
having a crushing strength not less than 3.5 MPa shall
be used. However, higher strength of masonry units
may be required depending upon number of storeys
and thickness of walls in accordance with provisions
of this Section.
7.3 Mortar
7.3.1 Mortars, such as those given in Table 13 or of
equivalent specification, shall preferably be used for
masonry construction for various categories of
buildings.
24
NATIONAL BUILDING CODE OF INDIA
Table 13 Recommended Mortar Mixes
(Clauses 7.3.1 and 1 Ah)
the toothed joint should be made in both the walls
alternatively in lifts of about 450 mm (see Fig. 14).
Category of
Proportion of Cemet-Lime-Sand 2)
Construction 1 >
0)
(2)
A
M2 (Cement-sand 1:6) or
M3 (Lime-cinder 3) 1:3) or richer
B, C
M2 (Cement-lime-sand 1:2:9 or
Cement-sand 1:6) or richer
D,E
H2 (Cement-sand 1:4) or
Ml (Cement-lime- sand 1:1:6) or richer
NOTE — Though the equivalent mortar with lime will have
less strength at 28 days, their strength after one year will be
comparable to that of cement mortar.
11 Category of construction is defined in Table 12.
2> Mortar grades and specification for types of limes etc, shall
be in accordance with Table 1.
3) In this case some other pozzolanic material like SURKHl
(burnt brick fine powder) may be used in place of cinder.
7.3.2 Where steel reinforcing bars are provided in
masonry the bars shall be embedded with adequate
cover in cement sand mortar not leaner than 1:3
(minimum clear cover 10 mm) or in cement concrete
of grade Ml 5 (minimum clear cover 15 mm or bar
diameter whichever more), so as to achieve good bond
and corrosion resistance.
7.4 Walls
7.4.1 Masonry bearing walls built in mortar, as
specified in 7.3.1 unless rationally designed as
reinforced masonry shall not be built of greater height
than 15 m subject to a maximum of four storeys when
measured from the mean ground level to the roof slab
or ridge level. The masonry bearing walls shall be
reinforced in accordance with 7.6.1.
7.4.2 The bearing walls in both directions shall be
straight and symmetrical in plan as far as possible.
7.4.3 The wall panels formed between cross walls and
floors or roof shall be checked for their strength in
bending as a plate or as a vertical strip subjected to the
earthquake force acting on its own mass.
NOTE — For panel walls of 200 mm or larger thickness having
a storey height not more than 3.5 m and laterally supported at
the top, this check need not be exercised.
7.4.4 Masonry Bond
For achieving full strength of masonry, the usual bonds
specified for masonry should be followed so that the
vertical joints are broken properly from course to
course. To obtain full bond between perpendicular
walls, it is necessary to make a slopping (stepped) joint
by making the corners first to a height of 600 mm and
then building the wall in between them. Otherwise,
a,b,c* Toothed joints in walls A, B and C
All dimensions in millimetres.
Fig. 14 Alternating Toothed Joints in Walls
at Corner and T- Junction
7.4.5 Ignoring tensile strength, free standing walls
shall be checked against overturning under the action
of design seismic coefficient cc h allowing for a factor
of safety of 1.5.
7.4.6 Panel or filler walls in framed buildings shall be
properly bonded to surrounding framing members by
means of suitable mortar (see Table 1 3) or connected
through dowels. If the walls are so bonded they shall
be checked according to 7.4.3 otherwise as in 7.4.5.
7.5 Openings in the Bearing Walls
7.5.1 Door and window openings in walls reduce their
lateral load resistance and hence, should preferably be
small and more centrally located. The guidelines on
the size and position of opening are given in Table 14
and Fig. 15.
7.5.2 Openings in any storey shall preferably have
their top at the same level so that a continuous band
could be provided over them, including the lintels
throughout the building.
7.5.3 Where openings do not comply with the
guidelines of Table 14, they should be strengthened
by providing reinforced concrete or reinforcing the
brickwork, as shown in Fig. 16 with high strength
deformed steel bars of 8 mm diameter but the quantity
of steel shall be increased at the jambs to comply
with 7.6.9, if so required.
7.5.4 If a window or ventilator is to be projected out,
the projection shall be in reinforced masonry or
concrete and well anchored.
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
25
Table 14 Size and Position of Openings in Bearing Walls
(Clause 7.5.1 and Fig. 15)
SI
No.
(1)
Position of Opening
(2)
Details of Opening for Building Category
AandB
(3)
C
(4)
DandE
(5)
i) Distance b$ from the inside corner of outside wall, Min
ii) For total length of openings, the ratio {b\ + bi + bi)l U or
(&, + bi)l h shall not exceed:
a) one-storeyed building
b) two-storeyed building
c) three or four-storeyed building
in) Pier width between consecutive openings b*, Min
iv) Vertical distance between two openings one above the other hi, Min
v) Width of opening of ventilator bs, Max
230 mm
450 mm
0.60
0.55
0.50
0.50
0.46
0.42
0.42
0.37
0.33
340 mm
450 mm
560 mm
600 mm
600 mm
600 mm
900 mm
900 mm
900 mm
/a
£>5
7735
i>i
J>±
b 2
h 2
bA
b3
bA
/?2
L
bA
b*\ a
V/\\V/> ' MV// //AW 777^777 ' 7/A&J// 777^777
1. DOOR 2. WINDOW 3. VENTILATOR 4. CROSS WALL
Fig. 15 Recommended Dimensions of Openings and Piers {see Table 14)
V = 2
m
SECTION AT XX
40 cf . , 40 cf
W = WINDOW
/ = WALL THICKNESS
/i = LINTEL THICKNESS
1 2 = THICKNESS OF CONCRETE IN JAMB
V= VERTICAL BAR
d = DIAMETER OF REINFORCING BARS
Fig. 16 Strengthening Masonary Around Opening
26
NATIONAL BUILDING CODE OF INDIA
7.5.5 If an opening is tall from bottom to almost top
of a storey, thus dividing the wall into two portions,
these portions shall be reinforced with horizontal
reinforcement of 6 mm diameter bars at not more than
450 mm intervals, one on inner and one on outer face,
properly tied to vertical steel at jambs, corners or
junction of walls, where used.
7.5.6 The use of arches to span over the openings is a
source of weakness and shall be avoided. Otherwise,
steel ties should be provided.
7.6 Seismic Strengthening Arrangements
7.6,1 All masonry buildings shall be strengthened by
the methods, as specified for various categories of
buildings, as listed in Table 15, and detailed
in subsequent clauses. Figures 17 and 18 show,
schematically, the overall strengthening arrangements
to be adopted for category D and E buildings which
consist of horizontal bands of reinforcement at critical
Table 15 Strengthening Arrangements
Recommended for Masonry Buildings
(Rectangular Masonry Units)
(Clause 7.6.1)
Building
Number of
Strengthening to be
Category
Storeys
Provided in all Storeys
(1)
(2)
(3)
A
i) 1 to 3
a
ii) 4
a, b,c
B
i) 1 to 3
a> b> c, /, g
ii) 4
a, b, c, d> /, g
C
i) 1 and 2
a,b,c,f,g
ii) 3 and 4
a log
D
i) 1 and 2
a tog
ii) 3 and 4
atoh
E
1 to 3 [)
aioh
where
a ~ Masonry mortar (see 7.3)
b - Lintel band (see 7.6.2)
c - Roof band and gable band where necessary (see 7.6.3
and 7.6.4),
d - Vertical steel atcorners and junctions of walls Oee 7.6.8)
e - Vertical steel at jambs of openings (see 7.6.9)
/ - Bracing in plan at tie level of roofs
g - Plinth band where necessary (see 7.6.6), and
h - Dowel bars (see 7.6.7)
1} Fourth storey not allowed in category E.
NOTE — In case of four storey buildings of category
B, the requirements of vertical steel may be checked
through a seismic analysis using a design seismic
coefficient equal to four times the one given in good
practice [6-4(8)] (this is because the brittle behaviour
of masonry in the absence of a vertical steel results in
much higher effective seismic force than that envisaged
in the seismic coefficient, provided in the Code). If this
analysis shows that vertical steel is not required the
designer may take the decision accordingly.
levels, vertical reinforcing bars at corners, junctions
of walls and jambs of opening.
7.6.2 Lintel band is a band provided at lintel level on
all load bearing internal, external longitudinal and cross
walls. The specifications of the band are given in 7.6.3.
NOTE — Lintel band if provided in panel or partition walls
also will improve their stability during severe earthquake.
7.6.3 Roof band is a band provided immediately below
the roof or floors. The specifications of the band are
given in 7.6.5. Such a band need not be provided
underneath reinforced concrete or brick-work slabs
resting on bearing walls, provided that the slabs are
continuous over the intermediate wall up to the crumple
sections, if any, and cover the width of end walls, fully
or at least 3 A of the wall thickness.
7.6.4 Gable band is a band provided at the top of gable
masonry below the purlins. The specifications of the
band are given in 7.6.5. This band shall be made
continuous with the roof band at the eaves level.
7.6.5 Section and Reinforcement of Band
The band shall be made of reinforced concrete of grade
not leaner than M 1 5 or reinforced brick work in cement
mortar not leaner than 1:3. The bands shall be of the
full width of the wall, not less than 15 mm in depth
and reinforced with steel, as indicated in Table 16.
NOTE — In coastal areas, the concrete grade shall be M20
concrete and the filling mortar of 1:3 (cement sand with water
proofing admixture).
Table 16 Recommended Longitudinal Steel in
Reinforced Concrete Bands
(Clauses 7.6.5 and 7.8.1 and Table 17)
Span Building Building Building Building
Category Category Category Category
B C D E
No. of Dia No. of Dia No. of Dia No. of Dia
Bars Bars Bars Bars
m mm mm mm mm
(1) (2) (3) (4) (5) (6) (7) (8) (9)
5 or less
2
8
2
8
2
8
2
10
6
2
8
2
/■8
2
10
2
12
7
2
8
2
10
2
12
4
10
8
2
10
2
12
4
10
4
12
NOTES
1 Span of wall will be the distance between centre lines of its
cross walls or buttresses. For spans greater than 8 m it will be
desirable to insert pilasters or buttresses to reduce the span or
special calculations shall be made to determine the strength of
wall and section of band.
2 The number and diameter of bars given above pertain to
high strength deformed bars. If plain mild steel bars are used
keeping the same number, the following diameters may be used:
High strength deformed 8 10 12 16 20
steel bar diameter .
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
27
1. LINTEL BAND
2. ROOF FLOOR BAND
3. VERTICAL BAR
4. DOOR
5. WINDOW
Fig. 17 Overall Arrangement of Reinforcing Masonry Buildings
2500 mm
8. HOLDING DOWN BOLT
9. BRICK/STONE WALL
10. DOOR LINTEL INTEGRATE
WITH ROOF BAND
1. LINTEL BAND
2. EAVE LEVEL (ROOF) BAND
3. CABLE BAND
4. DOOR
5. WINDOW
6. VERTICAL STEEL BAR
7. RAFTER
18 A PERSPECTIVE VIEW
1 8 B DETAILS OF TRUSS CONNECTION WITH WALL
1 8 C DETAILS OF INTEGRATING DOOR LINTEL WITH ROOF BAND
Fig. 18 Overall Arrangement of Reinforcing Masonry Building
having Pitched Roof
28
NATIONAL BUILDING CODE OF INDIA
Table 16 — Concluded
Mild steel plain deformed 10 12 16 20 25
bar diameter
3 Width of RC band is assumed same as the thickness of the
wall. Wall thickness shall be 200 mm minimum. A clear cover
of 20 mm from face of wall will be maintained.
4 The vertical thickness of RC band be kept 75 mm minimum,
where two longitudinal bars are specified, one on each face;
and 150 mm, where four bars are specified.
5 Concrete mix shall be of grade M 15 or 1 :2:4 by volume.
6 The longitudinal steel bars shall be held in position by steel
links or stirrups 6 mm dia spaced at 1 50 mm apart.
7.6.5.1 In case of reinforced brickwork, the thickness
of joints containing steel bars shall be increased so as
to have a minimum mortar cover of 10 mm around the
bar. In bands of reinforced brickwork the area of steel
provided should be equal to that specified above for
reinforced concrete bands.
7.6.5.2 For full integrity of walls at corners and junctions
of walls and effective horizontal bending resistance of
bands continuity of reinforcement is essential. The
details as shown in Fig. 19 are recommended.
7.6.6 Plinth band is a band provided at plinth level of
walls on top of the foundation wall. This is to be
provided where strip footings of masonry (other than
reinforced concrete or reinforced masonry) are used
and the soil is either soft or uneven in its properties, as
frequently happens in hill tracts. Where used, its section
may be kept same as in 7.6.5. This band will serve as
damp proof course as well.
7.6.7 In category D and E buildings, to further iterate
the box action of walls, steel dowel bars may be used
at corners and T-junctions of walls at the sill level of
windows to a length of 900 mm from the inside corner
in each wall. Such dowel may be in the form of U
stirrups of 8 mm diameter. Where used, such bars shall
be laid in 1:3 cement-sand-mortar with a minimum
cover of 10 mm on all sides to minimize corrosion.
7.6.8 Vertical Reinforcement
Vertical steel at corners and junctions of walls, which
are up to 340 mm (Wi brick) thick, shall be provided as
specified in Table 17. For walls thicker than 340 mm,
the area of the bars shall be proportionately increased.
19A SECTION OF BAND WITH TWO BARS
bl I
-Z+Tl
«£-
.'*•!-''.
l f ^#6 @t50
19B SECTION OF BAND WITH FOUR BARS
19C STRUCTURAL PLAN OF .„_, c ™ Tinkl Dl AM AT T „ , MrTr r,w
CORNER JUNCTION 1 9D SECTI °" .T^ 1 , ? T ' JUNCTr0N
OF WALL
1 . Longtudinal bars
2. Lateral ties
b^- Wall thickness
All dimensions in millimetres.
Fig. 19 Reinforcement and Bending Detail in R.C. Band
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
29
Table 17 Vertical Steel Reinforcement in Masonry Walls with
Rectangular Masonry Units
(Clauses 7.6.8, 7.6.9 and 8.7.2)
No. of Storeys
Storey
Diameter of HSD Single
Bar in mm at Each Critical Section
Category
B
Category C
Category D
Category E
(1)
(2)
(3)
(4)
(5)
(6)
One
—
Nil
Nil
10
12
Two
Top
Nil
Nil
10
12
Bottom
Nil
Nil
12
16
Three
Top
Nil
10
10
12
Middle
Nil
10
12
16
Bottom
Nil
12
12
16
Four
Top
Third
Second
Bottom
10
10
10
12
10
10
12
12
10
12
16
20
Four storeyed
building not
permitted
NOTES
1 The diameters given above are for high strength deformed steel bars. For mild steel plain bars, use equivalent diameters as given in
Table 16 (Note 2).
2 The vertical bars will be covered with concrete M 15 or mortar 1:3 grade in suitably created pockets around the bars. This will
ensure their safety from corrosion and good bond with masonry.
3 In case of floors/roofs with small precast components, also refer good practice [6-4(8)1 for floor/roof band details.
For earthquake resistant framed wall construction,
(see 7.7). No vertical steel need be provided in
category A buildings.
7.6.8.1 The vertical reinforcement shall be properly
embedded in the plinth masonry of foundations and
roof slab or roof band so as to develop its tensile
strength in bond. It shall be passing through the lintel
bands and floor level bands in all storeys.
Bars in different storeys may be welded or suitably
lapped.
NOTE — Typical details of providing vertical steel in
brickwork masonry with rectangular solid units at corners and
T-junctions are shown in Fig. 20.
7.6.9 Vertical reinforcement at jambs of window and
door openings shall be provided as per Table 17. It
may start from foundation of floor and terminate in
lintel band (see Fig. 21).
7.7 Framing of Thin Load Bearing Walls (see
Fig. 21)
Load bearing walls can be made thinner than 200 mm
say 150 mm inclusive of plastering on both sides.
Reinforced concrete framing columns and collar
beams will be necessary to be constructed to have
full bond with the walls. Columns are to be located at
all corners and junctions of walls and spaced not more
than 1.5 m apart but so located as to frame up the
doors and windows. The horizontal bands or ring
beams are located at all floors, roof as well as lintel
levels of the openings. The sequence of construction
between walls and columns will be first to build the
wall up to 4 to 6 courses height leaving toothed gaps
(tooth projection being about 40 mm only) for the
columns and second to pour M15 (1:2:4) concrete to
fill the columns against the walls using wood forms
only on two sides. The column steel should be
accurately held in position all along. The band
concrete should be cast on the wall masonry directly
so as to develop full bond with it.
Such construction may be limited to only two storeys
maximum in view of its vertical load carrying capacity.
The horizontal length of walls between cross walls shall
be restricted to 7 m and the storey height to 3 m.
7.8 Reinforcing Details for Hollow Block Masonry
The following details may be followed in placing the
horizontal and vertical steel in hollow block masonry
using cement-sand or cement-concrete blocks.
7.8.1 Horizontal Band
U-shaped blocks may be used for construction of
horizontal bands in various levels of the storeys as
shown in Fig. 22, where the amount of horizontal
reinforcement shall be taken 25 percent more than that
given in Table 16 and provided by using four bars and
6 mm dia stirrups. Other continuity details shall be
followed, as shown in Fig. 19.
30
NATIONAL BUILDING CODE OF INDIA
-thir-
1/2
1 1/2
-|-11- i-
1
v^
1/2
1/2
/"
1/2
1/2
1/4-
1/2
(a)
1—1*— I
+ * 1/2
i i
-^- _^_j4_j,^_
1/2
1/2
1/2
1/2
1/4
1/2
^r
1/2
Hr-*
X
— jWj-Lj-Wj
H
i—i-
1
i
-i--i
i—i-
L
1/2
rH
(b)
1/2_
1/2
1/2_
1/2
V2_
1/2
r
-4H
-V—V-
IH
T
H-
i— ^
/
IS
-1— J
17
I
(c)
1/2
1/2
1/2
1/2
yV
1/2
/
1/2 .
>.
\s
L I
1/2 *
m
L 1^
P
L I
!
k
■ikU
■ililfl
J-iJ-i-
Ll
(d)
1/4
I
J
1/
1/
■4
1/
>'■-■>■
nr~
2
2
2
x-V
2
y
X
^^s
/
^v
. i
-ta
•
" i
V
V
l
2 -
I 1 *
2 -
1
t I
"*■
4-
-i-
-i-
-jJ-i-
"i-
■i-
•*-
-f
.j-
(e)
(f)
1 — One-brick length, y 2 — Half brick length, V— Vertical steel bar with mortar/concrete filling in pocket
(a) and (b) — Alternate courses in one brick
(c) and (d) — Alternate courses at corner junction of 1 1 /2-brick wall
(e) and (f) — Alternate courses at T-junction of 1 1 / 2 -brick wall
Fig. 20 Typical Details of Providing Vertical Steel Bars
in Brick Masonry
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
31
L.
11*' . s ^ v ^ . ..
"T5 DETAIL X 7
1000
2000
1. WINDOW
2. DOOR
3. BRICK PANEL
4. LINTEL BAND
All dimensions in millimetres.
Fig. 21 Framing of Thin Load-Bearing Brick Walls
32
NATIONAL BUILDING CODE OF INDIA
Fig. 22 U-Blocks for Horizontal Bands
7.8.2 Vertical Reinforcement
Bars, as specified in Table 17 shall be located inside
the cavities of the hollow blocks, one bar in each cavity
(see Fig. 23). Where more than one bar is planned these
can be located in two or three consecutive cavities.
The cavities containing bars are to be filled by using
micro-concrete 1 :2:3 or cement-coarse sand mortar 1 :3,
and properly rodded for compaction. The vertical bars
should be spliced by welding or overlapping for
developing full tensile strength. For proper bonding,
the overlapped bars should be tied together by winding
the binding wire over the lapped length. To reduce the
number of overlaps, the blocks may be made U-shaped
as shown in Fig. 23 which will avoid lifting and
threading of bars into the hollows.
8 GUIDELINES FOR IMPROVING
EARTHQUAKE RESISTANCE OF LOW
STRENGTH MASONRY BUILDINGS
8.0 The term 'low strength masonry' includes fired
brickwork laid in clay mud mortar and random rubble;
uncoursed, undressed or semi-dressed stone masonry
in weak mortars; such as cement sand, lime sand and
clay mud. Special features of design and construction
for improving earthquake resistance of buildings of
low strength masonry are given in 8.1 to 8.4.7.
Reference may also be made to good practice [6-4(9)]
for detailed information.
8.1 General
8.1.1 Two types of construction are included herein,
namely:
a) Brick construction using weak mortar, and
b) Random rubble and half-dressed stone
masonry construction using different mortars,
such as, clay mud, lime-sand and cement
sand.
8.1.2 These constructions should not be permitted for
important buildings with / >1 .5 and should preferably
be avoided for building category D and shall not be
used for category E (see Table 12).
8.1.3 It will be useful to provide damp-proof course
at plinth level to stop the rise of pore water into the
superstructure.
8.1.4 Precautions should be taken to keep the rain
water away from soaking into the wall so that the
mortar is not softened due to wetness. An effective
way is to take out roof projections beyond the walls
by about 500 mm.
8.1.5 Use of a water-proof plaster on outside face of
walls will enhance the life of the building and maintain
its strength at the time of earthquake as well.
8.1.6 Ignoring tensile strength, free standing walls
should be checked against overturning under the action
of design seismic coefficient, a h , allowing for a factor
of safety of 1.5.
8.2 Brickwork in Weak Mortars
8.2.1 The fired bricks should have a compressive
strength not less than 3.5 MPa. Strength of bricks and
wall thickness should be selected for the total building
height.
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
33
I — II — II — I
D
n
D
D
□ CD
DCD C3
hi ii i r~i
D
D
D
D
D
LRJ
jgczi CD
o
-BINDING WIRE
Fig. 23 Vertical Reinforcement in Cavities
8.2.2 The mortar should be lime-sand (1:3) or clay
mud of good quality. Where horizontal steel is used
between courses, cement-sand mortar (1:3) should be
used with thickness so as to cover the steel with 6 mm
mortar above and below it. Where vertical steel is used,
the surrounding brickwork of 1 x 1 or \Vi x Wi brick
size depending on wall thickness should preferably be
built using 1:6 cement-sand mortar.
8.2.3 The minimum wall thickness shall be one brick
in one storey construction, and one brick in top storey
and \Vz brick in bottom storeys of up to three storey
construction. It should also not be less than 1/16 of the
length of wall between two consecutive perpendicular
walls.
8.2.4 The height of the building shall be restricted to
the following, where each storey height shall not
exceed 3.0 m:
a) For Categories A, B and C — three storeys
with flat roof; and two storeys plus attic for
pitched roof.
b) For Category D — two storeys with flat roof;
and one storey plus attic for pitched roof.
8.2.5 Special Bond in Brick Walls
For achieving full strength of masonry, the usual
bonds specified for masonry should be followed so
that the vertical joints are broken properly from course
to course. To obtain full bond between perpendicular
walls, it is necessary to make a sloping (stepped)
joint by making the corners first to a height of
600 mm and then building the wall in between them.
Otherwise the toothed joint should be made in both
the walls, alternatively in lifts of about 450 mm {see
Fig. 14).
34
NATIONAL BUILDING CODE OF INDIA
8.3 Stone Masonry (Random Rubble or Half-
Dressed)
8.3.1 The construction of stone masonry of random
rubble or dressed stone type should generally follow
good practice [6-4(3)1.
8.3.2 The mortar should be cement-sand (1:6), lime
sand (1:3) or clay mud of good quality.
8.3.3 The wall thickness i t 9 should not be larger
than 450 mm. Preferably it should be about 350 mm,
and the stones on the inner and outer wythes should be
interlocked with each other.
NOTE — If the two wythes are not interlocked, they tend to
delaminate during ground shaking bulge apart (see Fig. 24)
and buckle separately under vertical load leading to complete
collapse of the wall and the building.
1 . Half-cressed conical stone
2. Small alignment stone
3. Rotation of wythe
4. Random rubble
5. Mud or weak lime mortar
Fig. 24 Wall Delaminated with
Buckled Wythes
8.3.4 The masonry should preferably be brought to
courses at not more than 600 mm lift.
8.3.5 'Through 1 stones of full length equal to wall
thickness should be used in every 600 mm lift at not
more than 1.2 m apart horizontally. If full length stones
are not available, stones in pairs each of about 3 A of
the wall thickness may be used in place of one full
length stone so as to provide an overlap between them
(see Fig. 25).
8.3.6 In place of 'through' stones, 'bonding elements'
of steel bars 8 mm to 10 mm diameter bent to S -shape
or as hooked links may be used with a cover of 25 mm
from each face of the wall (see Fig. 25). Alternatively,
wood bars of 38 mm x 38 mm cross-section or concrete
bars of 50 mm x 50 mm section with an 8 mm diameter
rod placed centrally may be used in place of 'through'
stones. The wood should be well treated with
preservative so that it is durable against weathering
and insect action.
8.3.7 Use of 'bonding' elements of adequate length
should also be made at corners and junctions of walls
to break the vertical joints and provide bonding
between perpendicular walls.
8.3.8 Height of the stone masonry walls (random rubble
or half-dressed) should be restricted as follows, with
storey height to be kept 3.0 m maximum, and span of
walls between cross walls to be limited to 5.0 m:
a) For categories A and B — Two storeys with
flat roof or one storey plus attic, if walls are
built in lime-sand or mud mortar; and one
storey higher if walls are built in cement- sand
1:6 mortar.
b) For categories C and D — Two strorey s with
flat roof or two storeys plus attic for pitched
roof, if walls are built in 1:6 cement mortar;
and one storey with flat roof or one storey
plus attic, if walls are built in lime-sand or
mud mortar, respectively.
8.3.9 If walls longer than 5 m are needed, buttresses
may be used at intermediate points not farther apart
than 4.0 m. The size of the buttress be kept of uniform
thickness. Top width should be equal to the thickness
of main wall, f, and the base width equal to one- sixth
of wall height.
8.4 Opening in Bearing Walls
8.4.1 Door and window openings in walls reduce their
lateral load resistance and hence should preferably, be
small and more centrally located. The size and position
of openings shall be as given in Table 18 and Fig. 15.
8.4.2 Openings in any storey shall preferably have
their top at the same level so that a continuous band
could be provided over them including the lintels
throughout the building.
Table 18 Size and Position of Openings in
Bearing Walls (see Fig. 15)
(Clause 8.4.1)
SI
Description
Building Category
No.
r
■N
A,B&C
D
(1)
(2)
(3)
(4)
Distance b 5 from the inside corner of
outside wall, Min
230 mm
600 mm
ii)
Total length of openings, ratio; Max:
(bi + b 2 + bi)lh or (fc 5 + brilh
0.46
0.42
1) one storeyed building
0.37
0.33
2) 2 and 3 storeyed building
iii)
Pier width between consecutive
openings fc 4 ""
450 mm
560 mm
iv)
Vertical distance between two
openings one above the other, h 3 , Min
600 mm
600 mm
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
35
\>UbO
3 600 5S
25a SECTIONAL PLAN OF WALL
25b CROSS-SECTION OF WALL
1 . Through stone
2. Pair of overlapping stone
3. S-Shapetie
4. Hooked tie
5. Wood plank
6. Floor level
All dimensions in millimetres.
Fig. 25 Through Stone and Band Elements
8.4.3 Where openings do not comply with the
guidelines of Table 18, they should be strengthened
by providing reinforced concrete lining as shown in
Fig. 16 with 2 high strength deformed steel bars of
8 mm diameter.
8.4.4 The use of arches to span over the openings is a
source of weakness and shall be avoided, otherwise,
steel ties should be provided.
8.5 Seismic Strengthening Arrangements
8.5.1 All buildings to be constructed of masonry shall
be strengthened by the methods as specified for various
categories of buildings, listed in Table 19 and detailed
in subsequent clauses. Fig. 17 and Fig. 18 show,
schematically, the overall strengthening arrangements
to be adopted for category D buildings, which consist
of horizontal bands of reinforcement at critical levels
and vertical reinforcing bars at corners and junctions
of walls.
8.5.2 Lintel band is a band provided at lintel level on
all internal and external longitudinal as well as cross
walls except partition walls. The details of the band
are given in 8.5.5.
8.5.3 Roof band is a band provided immediately below
the roof or floors. The details of the band are given
in 8.5.5. Such a band need not be provided underneath
reinforced concrete or reinforced brick slabs resting
on bearing walls, provided that the slabs cover the
width of end walls fully.
8.5.4 Gable band is a band provided at the top of gable
Table 19 Strengthening Arrangements
Recommended for Low Strength
Masonry Buildings
(Clause 8.5.1)
Building Category
' Number of Storeys
Strengthening to
be Provided
(1)
(2)
(3)
A
1
2 and 3
b,c,fig
b,c,f,g
B
1 and 2
3
b,c,f,g
b,c,d,f,g
(see Note 1)
C
D
1
2 and 3
1 and 2
b,c,fig
b,c,.d,f,g
b,c,d,f,g
Strengthening
Method
b - Lintel band (see 8.5.2)
c - Roof band and gable band where necessary (see 8.5.3
and 8.5.4)
d - Vertical steel at corners and junctions of walls
(see 8.5.7)
/ - Bracing in plan at tie level of pitched roofs (see
Note 2)
g - Plinth band where necessary (see 8.5.6)
NOTES
1 For building of category B in two storeys constructed with
stone masonry in weak mortar, it will be desirable to provide
vertical steel of 10 mm dia in both storeys.
2 At tie level, all the trusses and the gable end should be
provided with diagonal braces in plan so as to transmit the
lateral shear due to earthquake force to the gable walls acting
as shear walls.
36
NATIONAL BUILDING CODE OF INDIA
masonry below the purlins. The details of the band are
given in 8.5.5. This band shall be made continuous
with the roof band at the eaves level.
8.5.5 Details of Band
8.5.5.1 Reinforced band
The band should be made of reinforced concrete of
grade not leaner than Ml 5 or reinforced brickwork in
cement mortar not leaner than 1:3. The bands should
be of full width of the wall, not less than 75 mm in
depth and should be reinforced with 2 high strength
deformed steel bars of 8 mm diameter and held in
position by 6 mm diameter bar links, installed at
150 mm apart as shown in Fig. 19.
NOTES
1 In coastal areas, the concrete grade shall be of grade in
accordance with Part 6 'Structural Design, Section 5 Concrete'
and the filling mortar of 1:3 ratio (cement-sand) with water
proofing admixture.
2 In case of reinforced brickwork, the thickness of joints
containing steel bars should be increased to 20 mm so as to
have a minimum mortar cover of 6 mm around the bar. In bands
of reinforced brickwork, the area of steel provided should be
equal to that specified above for reinforced concrete bands.
3 For full integrity of walls at corners and junctions of walls
and effective horizontal bending resistance of bands, continuity
of reinforcement is essential. The details as shown in Fig. 19
arc recommended.
8.5.5.2 Wooden band
As an alternative to reinforced band, the lintel band
could be provided using wood beams in one or two
parallel pieces with cross elements as shown in
Fig. 26.
8.5.6 Plinth band is a band provided at plinth level of
walls on top of the foundation wall. This is to be
provided where strip footings of masonry (other than
reinforced concrete or reinforced masonry) are used
and the soil is either soft or uneven in its properties as
frequently happens in hill tracts. Where used, its section
may be kept same as in 8.5.5.1. This band serves as
damp proof course as well.
8.5.7 Vertical Reinforcement
Vertical steel at corners and junctions of walls which
are up to 350 mm thick should be provided as specified
in Table 20. For walls thicker than 350 mm, the area
of the bars should be proportionately increased.
8.5.7.1 The vertical reinforcement should be properly
embedded in the plinth masonry of foundations and
roof slab or roof band so as to develop its tensile
strength in bond. It should pass through the lintel
bands and floor slabs or floor level bands in all
storeys. Bars in different storeys may be welded or
suitably lapped.
NOTES
1 Typical details of providing vertical steel in brickwork at
comers and T-junctions are shown in Fig. 20.
2 For providing vertical bar in stone masonry, use of a casing
pipe is recommended around which masonry be built to height
U^iUl
T
500
t
75x38
500
+
75x38
500
26a PERSPECTIVE VIEW
fl4-5 o o -+»- s o o -*!*■ 5?o-*|*- 5 ° ° -H— 50 °-H
T
JL
75x38
26b PLAN OF BAND
All dimensions in millimetres.
Fig. 26 Wooden Band for Low Strength Masonry Buildings
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
37
Table 20 Vertical Steel Reinforcement in Low Strength Masonry Walls
(Clause 8.5.7)
No. of
Storeys
Storey
Diameter of HSD Single Bar;
in mm,
at Each Critical Section for
Category A
Category B
Category C
Category D
(1)
(2)
(3)
(4)
(5)
(6)
One
—
Nil
Nil
Nil
10
Two
Top
Bottom
Nil
Nil
Nil
Nil
10
10
10
12
Three
Top
Middle
Bottom
Nil
. Nil
Nil
10
10
12
10
10
12
10
12
12
NOTES
1 The diameters given above are for High Strength Deformed bars with yield strength 415 MPa. For mild steel plain bars, use
equivalent diameters.
2 The vertical bars should be covered with concrete of M15 grade or with mortar 1:3 (cement-sand) in suitably created pockets around
the bars. This will ensure their safety from corrosion and good bond with masonry.
3 For category B two storey stone masonry buildings, see Note 1 under Table 19.
of 600 mm (see Fig. 27). The pipe is kept loose by rotating it
during masonry construction. It is then raised and the cavity
below is filled with M15 (or 1:2:4) grade of concrete mix and
rodded to compact it.
9 REINFORCED BRICK AND REINFORCED
BRICK CONCRETE FLOORS AND ROOFS
The construction and design of reinforced brick and
reinforced brick concrete floors and roof shall be in
accordance with good practices [6-4(10)].
10 NOTATIONS AND SYMBOLS
The various notations and letter symbols used in the
text of this Section of the Code shall have the meaning
as given in Annex E.
H'l-h-
1. Stonewall
2. Vertical steel bar
3. Casing pipe
4. Through stone or bonding element
Fig. 27 Typical Construction Detail for Installing Vertical Steel Bar in
Random Rubble Stone Masonry
38
NATIONAL BUILDING CODE OF INDIA
ANNEX A
(Clause 4.7)
SOME GUIDELINES FOR ASSESSMENT OF ECCENTRICITY OF
LOADING ON WALLS
A-l Where a reinforced concrete roof and floor slab
of normal span (not exceeding 30 times the thickness
of wall) bear on external masonry walls, the point of
application of the vertical loading shall be taken to
be at the centre of the bearing on the wall. When the
span is more than 30 times the thickness of wall, the
point of application of the load shall be considered
to be displaced from the centre of bearing towards
the span of the floor to an extent of one-sixth the
bearing width.
A-2 In case of a reinforced concrete slab of normal
span (that is, less than 30 times the thickness of the
wall), which does not bear on the full width of the wall
and 'cover tiles or bricks' are provided on the external
face, there is some eccentricity of load. The eccentricity
may be assumed to be one-twelfth of the thickness of
the wall.
A-3 Eccentricity of load from the roof/floor increases
with the increase in flexibility and thus deflection of
the slabs. Also, eccentricity of loading increases with
the increase in fixity of slabs/beams at supports.
Precast RCC slabs are better than in-situ slabs in this
regard because of very little fixity. If supports are
released before further construction on top, fixity is
reduced.
A-4 Interior walls carrying continuous floors are
assumed to be axially loaded except when carrying
very flexible floor or roof systems. The assumption is
valid also for interior walls carrying independent slabs
spanning from both sides, provided the span of the floor
on one side does not exceed that on the other by more
than 15 percent. Where the difference is greater, the
displacement of the point of application of each floor
load shall be taken as one-sixth of its bearing width on
the wall and the resultant eccentricity calculated
therefrom.
A-5 For timber and other lightweight floors, even for
full width bearing on wall, an eccentricity of about
one-sixth may be assumed due to deflection. For timber
floors with larger spans, that is, more than 30 times
the thickness of the wall, eccentricity of one-third the
thickness of the wall may be assumed.
A-6 In multi-storeyed buildings, fixity and eccentricity
have normally purely local effect and are not
cumulative. They just form a constant ripple on the
downward increasing axial stress. If the ripple is large,
it is likely to be more serious at upper levels where it
can cause cracking of walls than lower down where it
may or may not cause local over-stressing.
NOTE — The resultant eccentricity of the total loads on a
wall at any level may be calculated on the assumption that
immediately above a horizontal lateral support, the resultant
eccentricity of all the vertical loads above that level is zero.
A-7 For a wall corbel to support some load, the point
of application of the load shall be assumed to be at the
centre of the bearing on the corbel.
ANNEX B
(Clause 5.4.1)
CALCULATION OF BASIC COMPRESSIVE STRESS OF
MASONRY BY PRISM TEST
B-l DETERMINATION OF COMPRESSIVE
STRENGTH OF MASONRY BY PRISM TEST
When compressive strength of masonry (/' ) is to be
established by tests, it shall be done in advance of
the construction, using prisms built of similar
materials under the same conditions with the same
bonding arrangement as for the structure. In building
the prisms, moisture content of the units at the time
of laying, the consistency of the mortar, the thickness
of mortar joints and workmanship shall be the same
as will be used in the structure. Assembled specimen
shall be at least 400 mm high and shall have a height
to thickness ratio (hit) of at least 2 but not more than
5. If the hit ratio of the prisms tested is less than 5 in
case of brickwork and more than 2 in case of
blockwork, compressive strength values indicated by
the tests shall be corrected by multiplying with the
factor indicated in Table 21.
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
39
Table 21 Correction Factors for Different
hit Ratios
{Clause B-\ A)
Ratio of Height to 2.0 2.5 3.0 3.5 4.0 5.0
Thickness {hit)
Correction Factors 0.73 0.80 0.86 0.91 0.95 1.00
for Brickwork 1 *
Correction Factors 1.00 — 1.20 — 1.30 1.37
for Blockwork 1 *
11 Interpolation is valid for intermediate values.
Prisms shall be tested after 28 days between sheets of
nominal 4 mm plywood, slightly longer than the bed
area of the prism, in a testing machine, the upper
platform of which is spherically seated. The load shall
be evenly distributed over the whole top and bottom
surfaces of the specimen and shall be applied at the
rate of 350 kN/m to 700 kN/m. The load at failure
should be recorded.
B-2 CALCULATION OF BASIC COMPRESSIVE
STRESS
Basic compressive stress of masonry shall be
taken to be equal to 0.25/^, where f m is the value of
compressive strength of masonry as obtained from
prism test.
ANNEX C
(Clauses 5.3.3 and 5.4.1.5)
GUIDELINES FOR DESIGN OF MASONRY SUBJECTED TO
CONCENTRATED LOADS
C-l EXTENT OF DISPERSAL OF
CONCENTRATED LOAD
For concentric loading, maximum spread of a
concentrated load on a wall may be taken to be equal
to b+4t (b is width of bearing and t is thickness of
wall), or stretch of wall supporting of load, or centre-
to-centre distance between loads, whichever is less.
C-2 INCREASE IN PERMISSIBLE STRESS
C-2.1 When a concentrated load bears on a central
strip of wall, not wider than half the thickness of the
wall and is concentric, bearing stress in masonry may
exceed the permissible compressive stress by 50
percent, provided the area of supporting wall is not
less than three times the bearing area.
C-2.2 If the load bears on full thickness of wall and is
concentric, 25 percent increase in stress may be
allowed.
C-2.3 For loading on central strip wider than half the
thickness of the wall but less than full thickness,
increase in stress may be worked out by interpolation
between values of increase in stresses as given
in C-2.1 and C-2.2.
C-2.4 In case concentrated load is from a lintel over
an opening, an increase of 50 percent in permissible
stress may be taken, provided the supporting area is
not less than 3 times the bearing area.
C-3 CRITERIA OF PROVIDING BED BLOCK
C-3.1 If a concentrated load bears on one end of a
wall, there is a possibility of masonry in the upper
region developing tension. In such a situation, the load
should be supported on an RCC bed block (of Ml 5
Grade) capable of taking tension.
C-3.2 When any section of masonry wall is subjected
to concentrated as well as uniformly distributed
load and resultant stress, computed by making due
allowance for increase in stress on account of
concentrated load, exceeds the permissible stress
in masonry, a concrete bed block (of M15 Grade)
should be provided under the load in order to
relieve stress in masonry. In concrete, angle of
dispersion of concentrated load is taken to be 45° to
the vertical.
C-3.3 In case of cantilevers and long span beams
supported on masonry walls, indeterminate but very
high edge stresses occur at the supports and in such
cases it is necessary to relieve stress on masonry by
providing concrete bed block of M15 Grade concrete.
Similarly when a wall is subjected to a concentrated
load from a beam which is not sensibly rigid (for
example, a timber beam or an RS joist), a concrete bed
block should be provided below the beam in order to
avoid high edge stress in the wall because of excessive
deflection of the beam.
40
NATIONAL BUILDING CODE OF INDIA
ANNEX D
(Clause 5.5.5)
GUIDELINES FOR APPROXIMATE DESIGN OF NON-LOAD BEARING WALL
D-l PANEL WALLS
A panel wall may be designed approximately as under,
depending upon its support conditions and certain
assumptions:
a) When there are narrow tall windows on either
side of panel, the panel spans in the vertical
direction. Such a panel may be designed for
a bending moment of P///8, where P is the
total horizontal load on the panel and H is the
height between the centres of supports. Panel
wall is assumed to be simply supported in the
vertical direction.
b) When there are long horizontal windows
between top support and the panel, the top
edge of the panel is free. In this case, the panel
should be considered to be supported on sides
and at the bottom, and the bending moment
would depend upon height to length ratio of
panel and flexural strength of masonry.
Approximate values of bending moments in
the horizontal direction for this support
condition, when ratio (ji) of flexural strength
of wall in the vertical direction to that in
horizontal direction is assumed to be 0.5, are
given in Table 22.
Table 22 Bending Moments in Laterally Loaded
Panel Walls, Free at Top Edge and Supported
on Other Three Edges
Table 23 Bending Moments in Laterally
Loaded Panel Walls Supported
on All Four Edges
Height of Panel, H
Length of Panel, L
Bending Moment
0.30 0.50 0.75 1.00 1,25 1.50 1.75
PL PL PL PL PL PL PL
25 18 14 12 11 10.5 10
NOTE — For H/L ratio less than 030, the panel should be
designed as a free-standing wall and for H/L ratio exceeding
1 .75, it should be designed as a horizontally spanning membei
for a bending moment value of PL/8.
c) When either there are no window openings
or windows are of 'hole-in-wall' type, the
panel is considered to be simply supported
on all four edges. In this case also, amount of
maximum bending moment depends on
height to length ratio of panel and ratio (p) of
flexural strength of masonry in vertical
direction to that in the horizontal direction.
Approximate values for maximum bending
moment in the horizontal direction for
masonry with jj = 0.50, are given in Table 23.
Height of Panel, H
Length of Panel, L
Bending Moment
0.30 0.50 0.75 1.00 1.25 1.50 1.75
P.L PL PL PL PL PL P.L
72 36 24 18 15 13 12
NOTE — When H/L is less than 0.30, value of bending
moment in the horizontal direction may be taken as nil and
panel wall may be designed for a bending moment value of
P/f/8 in the vertical direction; when H/L exceeds 1,7.5, panel
may be assumed to be spanning in the horizontal direction and
designed for bending moment of PL/8.
D-2 CURTAIN WALLS
Curtain walls may be designed as panel walls taking
into consideration the actual supporting conditions.
D-3 PARTITION WALLS
D-3.1 These are internal walls usually subjected to
much smaller lateral forces. Behaviour of such wall is
similar to that of panel wall and these could, therefore,
be designed on similar lines. However, in view of
smaller lateral loads, ordinarily these could be
apportioned empirically as follows:
a) Walls with adequate lateral restraint at both
ends but not at the top:
1 ) The panel may be of any height, provided
the length does not exceed 40 times the
thickness; or
2) The panel may be of any length, provided
the height does not exceed 15 times the
thickness (that is, it may be considered
as a free-standing wall); or
3) Where the length of the panel is over 40
times and less than 60 times the thickness,
the height plus twice the length may not
exceed 135 times the thickness;
b) Walls with adequate lateral restraint at both
ends at the top:
1 ) The panel may be of any height, provided
the length does not exceed 40 times the
thickness; or
2) The panel may be of any length, provided
the height does not exceed 30 times the
thickness; or
3) Where the length of the panel is over
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
41
40 times and less than 110 times the
thickness, the length plus three times the
height should not exceed 200 times the
thickness; and
c) When walls have adequate lateral resistant at
the top but not at the ends, the panel may be
of any length, provided the height does not
exceed 30 times the thickness.
D-3.2 Strength of bricks used in partition walls should
not be less than 3.5 N/mm 2 or the strength of masonry
units used in adjoining masonry, whichever is less.
Grade of mortar should not be leaner than M2.
ANNEX E
(Clause 10)
NOTATIONS, SYMBOLS AND ABBREVIATIONS
E-l The following notations, letter symbols and
abbreviations shall have the meaning indicated against
each, unless otherwise specified in the text of this
Section of the Code:
A - Area of a section
b - Width of bearing
DPC ~ Damp proof course
e - Resultant eccentricity
/ = Basic compressive stress
/, = Permissible compressive stress
f = Compressive stress due to dead loads
f = Permissible shear stress
J R
f = Compressive strength of masonry (in
prism test)
GL - Ground level
H ~ Actual height between lateral supports
H J - Height of opening
//l, H2 = High strength mortars
h = Effective height between lateral
supports
k = Area factor
k
p
-
Shape modification factor
k
s
=
Stress reduction factor
L
=
Actual length of wall
LI, 12
=
Lower strength mortars
M%M2
Medium strength mortars
P
=
Total horizontal load
PL
=
Plinth level
RCC
=
Reinforced cement concrete
RS
=
Rolled steel
S
p
=
Spacing of piers/buttresses/cross walls
SR
=
Slenderness ratio
t
=
Actual thickness
t
p
=
Thickness of pier
t
w
=
Thickness of wall
W
=
Resultant load
W,
=
Axial load
w 2
=
Eccentric load
W
P
=
Width of piers/buttresses/cross walls
t*
=
Ratio of flexural strength of wall in
the vertical direction to that in the
horizontal direction.
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and 'accepted standards'
in the fulfillment of the requirements of the Code. The
latest version of a standard shall be adopted at the time
of enforcement of the Code. The standards listed may
be used by the Authority as a guide in conformance
with the requirements of the referred clauses in the
Code.
In the following list, the number appearing in the first
column within parentheses indicates the number of the
reference in this Part/Section.
IS No.
(1) 1077: 1992
2180: 1988
2185
(Part 1): 1979
Title
Specification for common
burnt clay building bricks
(fifth revision)
Specification for heavy duty
burnt clay building bricks
(third revision)
Specification for concrete
masonry units:
Hollow and solid concrete
blocks (second revision)
42
NATIONAL BUILDING CODE OF INDIA
IS No.
(Part 2) : 1983
(Part 3) ; 1984
2222: 1991
2849 : 1983
3115: 1992
3316: 1974
3620 : 1979
3952 : 1988
4139 : 1989
12440 : 1988
12894 : 2002
13757 : 1993
(2) 2250: 1981
(3) 1597
(Part 1) : 1992
(Part 2) : 1992
2110: 1980
Title
Hollow and solid light weight
concrete blocks (first revision)
Autoclaved cellular aerated
concrete blocks (first revision)
Specification for burnt clay
perforated building bricks
(fourth revision)
Specification for non-load
bearing gypsum partition blocks
(solid and hollow types) (first
revision)
Specification for lime based
blocks (second revision)
Specification for structural
granite (first revision)
Specification for laterite stone
block for masonry (first revision)
Specification for burnt clay
hollow blocks for walls and
partitions (second revision)
Specification for calcium
silicate bricks (second revision)
Specification for precast
concrete stone masonry blocks
Specification for pulverized fuel
ash lime bricks (first revision)
Specification for burnt clay fly
ash building bricks
Code of practice for preparation
and use of masonry mortars (first
revision)
Code of practice for construction
of stone masonry:
Rubble stone masonry (first
revision)
Ashlar masonry (first revision)
Code of practice for in-situ
construction of walls, in
building with soil-cement (first
revision)
IS No.
2212 : 1991
2572 : 1963
2849 : 1983
3630 : 1992
4326 : 1993
6041 : 1985
6042 : 1969
(4) 2212 : 1991
(5) 3414 : 1968
(6) 4326 : 1993
(7) 1905 : 1987
(8) 1893
(Part 1) : 2002
(9) 13828 : 1993
(10) 10440: 1983
Title
Code of practice for brickwork
(first revision)
Code of practice for construction
of hollow concrete block
masonry
Specification for non-load
bearing gypsum partition blocks
(solid and hollow types) (first
revision)
Code of practice for construction
of non-load bearing gypsum
block partitions (first revision)
Code of practice for earthquake
resistant design and construction
of buildings (second revision)
Code of practice for construction
of autoclaved cellular concrete
block masonry (first revision)
Code of practice for construction
of lightweight concrete block
masonry
Code of practice for brickwork
(first revision)
Code of practice for design
and installation of joints in
buildings
Code of practice for earthquake
resistant design and construction
of buildings (second revision)
Code of practice for structural
use of un-reinforced masonry
(third revision)
Criteria for earthquake resistant
design of structures: Part 1
General provisions and buildings
(fifth revision)
Guidelines for improving
earthquake resistance of low
strength masonry buildings
Code of practice for construction
of RB and RBC floors and roofs
PART 6 STRUCTURAL DESIGN — SECTION 4 MASONRY
43
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 5 Concrete: 5A Plain and Reinforced Concrete
BUREAU OF INDIAN STANDARDS
FOREWORD
CONTENTS
1 SCOPE
2 TERMINOLOGY
3 SYMBOLS
SECTION 5A (a) GENERAL
7
7
7
SECTION 5A (b) MATERIALS, WORKMANSHIP,
INSPECTION AND TESTING
4 MATERIALS
5 CONCRETE
6 WORKABILITY OF CONCRETE
7 DURABILITY OF CONCRETE
8 CONCRETE MIX PROPORTIONING
9 PRODUCTION OF CONCRETE
10 FORMWORK
11 ASSEMBLY OF REINFORCEMENT
12 TRANSPORTING, PLACING, COMPACTION AND CURING
1 3 CONCRETING UNDER SPECIAL CONDITIONS
14 SAMPLING AND STRENGTH OF DESIGNED CONCRETE MIX
15 ACCEPTANCE CRITERIA
1 6 INSPECTION AND TESTING OF STRUCTURES
11
12
12
17
18
20
21
22
23
24
25
25
SECTION 5A (c) GENERAL DESIGN CONSIDERATION
17 BASES FOR DESIGN
18 LOADS AND FORCES
1 9 STABILITY OF THE STRUCTURE
20 FIRE RESISTANCE
21 ANALYSIS
22 BEAMS
23 SOLID SLABS
24 COMPRESSION MEMBERS
25 REQUIREMENTS GOVERNING REINFORCEMENT AND DETAILING
26 EXPANSION JOINTS
26
27
28
28
28
31
33*
36
37
45
SECTION 5A (d) SPECIAL DESIGN REQUIREMENTS FOR
STRUCTURAL MEMBERS AND SYSTEMS
27 CONCRETE CORBELS
28 DEEP BEAMS
29 RIBBED, HOLLOW BLOCK OR VOIDED SLAB
30 FLAT SLABS
45
46
47
48
NATIONAL BUILDING CODE OF INDIA
31 WALLS
32 STAIRS
33 FOOTINGS
57
59
59
SECTION 5A (e) STRUCTURAL DESIGN
(LIMIT STATE METHOD)
34 SAFETY AND SERVICEABILITY REQUIREMENTS
35 CHARACTERISTIC AND DESIGN VALUES AND PARTIAL SAFETY
FACTORS
36 ANALYSIS
37 LIMIT STATE OF COLLAPSE: FLEXURE
38 LIMIT STATE OF COLLAPSE: COMPRESSION
39 LIMIT STATE OF COLLAPSE: SHEAR
40 LIMIT STATE OF COLLAPSE: TORSION
4 1 LIMIT STATE OF SERVICEABILITY: DEFLECTION
42 LIMIT STATE OF SERVICEABILITY: CRACKING
ANNEX A SELF COMPACTING CONCRETE
ANNEX B STRUCTURAL DESIGN (WORKING STRESS METHOD)
ANNEX C CALCULATION OF DEFLECTION
ANNEX D SLABS SPANNING IN TWO DIRECTIONS
ANNEX E EFFECTIVE LEGNTH OF COLUMNS
ANNEX F CALCULATION OF CRACK WIDTH
ANNEX G MOMENTS OF RESISTANCE FOR RECTANGULAR AND
T-SECTIONS
LIST OF STANDARDS
62
63
64
64
65
67
70
71
71
72
72
79
80
83
86
87
88
PART 6 STRUCTURAL DESIGN — SECTION 5 CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
National Building Code Sectional Committee, CED 46
FOREWORD
Section 5 of Part 6 of the Code covers plain and reinforced concrete as also the prestressed concrete. The Section
has been subdivided into the following sub-sections:
5 A Plain and Reinforced Concrete
5 B Prestressed Concrete
This sub-section 5A covers the structural design aspects of plain and reinforced concrete.
This sub-section 5A was first published in 1970 and was subsequently revised in 1983, to bring it in line with
revised version of IS 456 : 1978 on which this chapter was based. Now this revision is intended to bring this
subsection in line with the revised version of IS 456 : 2000.
This revision incorporates a number of important changes. The major thrust in the revision is on the following lines:
a) In recent years, durability of concrete structures have become the cause of concern to all concrete
technologists. This has led to codify the durability requirements world over. In this revision of the
Code, in order to introduce in-built protection from factors affecting a structure, earlier clause on durability
has been elaborated and a detailed clause covering different aspects of design of durable structure has
been incorporated.
b) Sampling and acceptance criteria for concrete have been revised. With this revision acceptance criteria
has been simplified in line with the provisions given in BS 5328 (Part 4) : 1990 'Concrete: Part 4
Specification for the procedures to be used in sampling, testing and assessing compliance of concrete'.
Some of the significant changes incorporated in Section 5A (b) are as follows:
a) All the three grades of ordinary Portland cement, namely 33 grade, 43 grade and 53 grade and sulphate
resisting Portland cement have been included in the list of types of cement used (in addition to other
types of cement),
b) The permissible limits for solids in water have been modified keeping in view the durability requirements.
c) The clause on admixtures has been modified in view of the availability of new types of admixtures
including superplasticizers.
d) In Table 2 'Grades of Concrete', grades higher than M 40 have been included.
e) It has been recommended that minimum grade of concrete shall be not less than M 20 in reinforced
concrete work (see also 5.1.3).
f) The formula for estimation of modulus of elasticity of concrete has been revised.
g) In the absence of proper correlation between compacting factor, vee-bee time and slump, workability
has now been specified only in terms of slump in line with the provisions in BS 5328 (Parts 1 to 4).
h) Durability clause has been enlarged to include detailed guidance concerning the factors affecting
durability. The table on 'Environmental Exposure Conditions' has been modified to include 'very severe'
and 'extreme' exposure conditions. This clause also covers requirements for shape and size of member,
depth of concrete cover, concrete quality, requirement against exposure to aggressive chemical and
sulphate attack, minimum cement requirement and maximum water cement ratio, limits of chloride
content, alkali silica reaction, and importance of compaction, finishing and curing.
j) A clause on 'Quality Assurance Measures' has been incorporated to give due emphasis to good practices
of concreting.
k) Proper limits have been introduced on the accuracy of measuring equipments to ensure accurate batching
of concrete.
m) The clause on 'Construction Joints' has been modified.
n) The clause on 'Inspection' has been modified to give more emphasis on quality assurance.
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE 5
The significant changes incorporated in Section 5A (c) are as follows:
a) Requirements for Tire Resistance' have been further detailed.
b) The figure for estimation of modification factor for tension reinforcement used in calculation of basic
values of span to effective depth to control the deflection of flexural member has been modified.
c) Recommendations regarding effective length of cantilever have been added.
d) Recommendations regarding deflection due to lateral loads have been added.
e) Recommendations for adjustments of support moments in restrained slabs have been included.
f) In the determination of effective length of compression members, stability index has been introduced to
determine sway or no sway conditions.
g) Recommendations have been made for lap length of hooks for bars in direct tension and flexural tension.
h) Recommendations regarding strength of welds have been modified.
j) Recommendations regarding cover to reinforcement have been modified. Cover has been specified based
on durability requirements for different exposure conditions. The term 'nominal cover' has been introduced.
The cover has now been specified based on durability requirement as well as for fire requirements.
The significant change incorporated in Section 5A (d) is the modification of the clause on Walls. The modified
clause includes design of walls against horizontal shear.
In Section 5 on limit state method a new clause has been added for calculation of enhanced shear strength of
sections close to supports. Some modifications have also been made in the clause on Torsion. Formula for
calculation of crack width has been added (separately given in Annex F).
Working stress method has now been given in Annex B so as to give greater emphasis to limit state design. In this
Annex, modifications regarding torsion and enhanced shear strength on the same lines as in Section 5 have been
made.
Whilst the common methods of design and construction have been covered in this Code, special systems of design
and construction of any plain or reinforced concrete structure not covered by this Code may be permitted on
production of satisfactory evidence regarding their adequacy and safety by analysis or test or both {see 18).
In this Code it has been assumed that the design of plain and reinforced cement concrete work is entrusted to a
qualified engineer and that the execution of cement concrete work is carried out under the direction of a qualified
and experience supervisor.
This Section also introduces self-compacting concrete {see Annex A).
In the formulation of this subsection, assistance has been derived from the following publications:
BS 5328 (Part 1) : 1991 Concrete: Part 1 Guide to specifying concrete, British Standards Institution
BS 5328 (Part 2) : 1991 Concrete: Part 2 Methods for specifying concrete mixes, British Standards Institution
BS 5328 (Part 3) : 1990 Concrete: Part 3 Specification for the procedures to be used in producing and
transporting concrete, British Standards Institution
BS 5328 (Part 4) : 1990 Concrete: Part 4 Specification for the procedures to be used in sampling, testing and
assessing compliance of concrete, British Standards Institution
BS 8110 (Part 1) : 1985 Structural use of concrete: Part 1 Code of practice for design and construction,
British Standards Institution
BS 81 10 (Part 2) : 1985 Structural use of concrete: Part 2 Code of practice for special circumstances, British
Standards Institution
ACI 318 : 1995 Building code requirements for reinforced concrete, American Concrete Institute
AS 3600 : 1988 Concrete structures, Standards Association of Australia
DIN 1045 July 1988 Structural use of concrete, design and construction, Deutsches Institut fur Normung
E.V.
CEB-FIP Model Code 1990, Cornite Euro International Du Belon
All standards, whether given herein above or cross-referred to in the main text of this Section, are subject to
revision. The parties to agreement based on this Section are encouraged to investigate the possibility of applying
the most recent editions of the standards.
6 NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 5 Concrete: 5A Plain and Reinforced Concrete
SECTION 5A (a) GENERAL
1 SCOPE
1.1 This Section deals with the general structural use
of plain and reinforced concrete.
1.1.1 For the purpose of this Section, plain concrete
structures are those where reinforcement, if provided
is ignored for determination of strength of the structure.
1.2 Design of special requirements of structures, such
as shells, folded plates, arches, bridges, chimneys, blast
resistant structures, hydraulic structures, liquid
retaining structures and earthquake resistant structures,
shall be done in accordance with good practice
[6-5A(l)].
2 TERMINOLOGY
For the purpose of this Section, the definitions given
in accepted standards [6-5 A(2)].
3 SYMBOLS
For the purpose of this standard, the following letter
symbols shall have the meaning indicated against each;
where other symbols are used, they are explained at
the appropriate place:
A -
b -
K "
b -
w
D -
DL
d
d'
E -
C
EL -
E -
s
e -
L
Area
Breadth of beam, or shorter dimension of
a rectangular column
Effective width of slab
- Effective width of flange
- Breadth of web or rib
- Overall depth of beam or slab or diameter
of column; dimension of a rectangular
column in the direction under consideration
- Thickness of flange
- Dead load
- Effective depth of beam or slab
- Depth of compression reinforcement from
the highly compressed face
- Modulus of elasticity of concrete
- Earthquake load
- Modulus of elasticity of steel
Eccentricity
Characteristic cube compressive strength
of concrete
Modulus of rupture of concrete (flexural
tensile strength)
/«,
- Splitting tensile strength of concrete
/,
- Design strength
/,
- Characteristic strength of steel
H
W
- Unsupported height of wall
H
we
- Effective height of wall
I*
- Effective moment of inertia
7 gr
- Moment of inertia of the gross section
excluding reinforcement
r
- Moment of intertia of cracked section
K
- Stiffness of member
k
- Constant or coefficient or factor
h
- Development length
LL
- Live load or imposed load
I
- Length of a column or beam between
adequate lateral restraints or the
unsupported length of a column
h<
- Effective span of beam or slab or effective
length of column
I
ex
- Effective length about x-x axis
/
ey
- Effective length about y-y axis
I
n
- Clear span, face-to-face of supports
C
- /' ef for shorter of the two spans at right
angles
I
X
- Length of shorter side of slab
I
y
- Length of longer side of slab
'o
- Distance between points of zero moments
in a beam
K
- Span in the direction in which moments
are determined, centre-to-centre of
supports
K
- Span transverse to l v centre-to-centre of
supports
i\
- l 2 for the shorter of the continuous spans
M
- Bending moment
m
- Modular ratio
n
- Number of samples
P
- Axial load on a compression member
<?o
- Calculated maximum bearing pressure
%
- Calculated maximum bearing pressure of
soil
r
- Radius
s
- Spacing of stirrups or standard deviation
T
- Torsional moment
t
- Wall thickness
V
- Shear force
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
w
- Total load
WL
- Wind load
w
- Distributed load per unit area
W 6
- Distributed dead load per unit area
W l
- Distributed imposed load per unit area
X
- Depth of neutral axis
Z
- Modulus of section
z
- Lever arm
a,P
- Angle or ratio
Y f
- Partial safety factor for load
Y m
- Partial safety factor for material
d
- Percentage reduction in moment
e
cc
- Creep strain of concrete
cbc
- Permissible stress in concrete in bending
compression
a
cc
- Permissible stress in concrete in direct
compression
a
mc
- Permissible stress in metal in direct
compression
a
EC
- Permissible stress in steel in compression
CT S ,
- Permissible stress in steel in tension
a
sv
- Permissible stress in shear reinforcement
\.
- Design bond stress
T
C
- Shear stress in concrete
T
c, max
- Maximum shear stress in concrete with
shear reinforcement
T
V
- Nominal shear stress
- Diameter of bar
SECTION 5A (b)
MATERIALS, WORKMANSHIP,
INSPECTION AND TESTING
4 MATERIALS
4.1 Cement
The cement used shall be any of the following
conforming to accepted standards [6-5A(3)] and the
type selected should be appropriate for the intended
use:
a) 33 grade ordinary Portland cement
b) 43 grade ordinary Portland cement
c) 53 grade ordinary Portland cement
d) Rapid hardening Portland cement
e) Portland slag cement
f) Portland pozzolana cement (fly ash based)
g) Portland pozzolana cement (calcined clay
based)
h) Hydrophobic cement
j) Low heat Portland cement
k) Sulphate resisting Portland cement
Other combinations of Portland cement with mineral
admixture (see 4.2) of quality conforming with relevant
Indian Standards laid down may also be used in the
manufacture of concrete provided that there are
satisfactory data on their suitability, such as
performance test on concrete containing them.
4.1.1 Low heat Portland cement conforming to
accepted standards [6-5A(3)J shall be used with
adequate precautions with regard to removal of
formwork, etc.
4.1.2 High alumina cement or supersulphated cement
conforming to accepted standards [6-5A(4)J may be
used only under special circumstances with the prior
approval of the engineer-in-charge. Specialist literature
may be consulted for guidance regarding the use of
these types of cements.
4.1.3 The attention of the engineer-in-charge and users
of cement is drawn to the fact that quality of various
cements mentioned in 4.1 is to be determined on
the basis of its conformity to the performance
characteristics given in the respective Indian Standard
Specification for that cement. Any trade-mark or any
trade name indicating any special features not covered
in the standard or any qualification or other special
performance characteristics sometimes claimed/
indicated on the bags or containers or in advertisements
alongside the 'Statutory Quality Marking' or otherwise
have no relation whatsoever with the characteristics
guaranteed by the Quality Marking as relevant to that
cement. Consumers are, therefore, advised to go by
the characteristics as given in the corresponding Indian
Standard Specification or seek specialist advise
to avoid any problem in concrete making and
construction.
4.2 Mineral Admixtures
4.2.1 Pozzolanas
Pozzolanic materials conforming to relevant Indian
Standards may be used with the permission of the
engineer-in-charge, provided uniform blending with
cement is ensured.
4.2.1.1 Fly ash (pulverized fuel ash)
Fly ash conforming to Grade 1 of accepted standards
[6-5 A(5)] may be used as part replacement of ordinary
Portland cement provided uniform blending with
cement is ensured.
4.2.1.2 Silica fume
Silica fume conforming to a standard approved by the
deciding authority may be used as part replacement of
NATIONAL BUILDING CODE OF INDIA
cement provided uniform blending with the cement is
ensured.
NOTE — The silica fume (very fine non-crystalline silicon
dioxide) is a by-product of the manufacture of silicon,
ferrosilicon or the like, from quartz and carbon in electric are
furnace. It is usually used in proportion of 5 to 10 percent of
the cement content of a mix.
4.2.1.3 Rice husk ash
Rice husk ash giving required performance and
uniformity characteristics may be used with the
approval of the deciding authority.
NOTE — Rice husk ash is produced by burning rice husk and
contain large proportion of silica. To achieve amorphous state,
rice husk may be burnt at controlled temperature. It is necessary
to evaluate the product from a particular source for performance
and uniformity since it can be as deleterious as silt when
incorporated in concrete. Water demand and drying shrinkage
should be studied before using rice husk.
4.2.1.4 Metakaoline
Metakaoline having fineness between 700 to
900 m 2 /kg may be used as pozzolanic material in
concrete.
NOTE — Metakaoline is obtained by clacination of pure or
refined kaolintic clay at a temperature between 650°C and
850 D C, followed by grinding to achieve a fineness of 700 to
900 m 2 /kg. The resulting material has high pozzolanicity.
4.2.2 Ground Granulated Blast Furnace Slag
Ground granulated blast furnace slag obtained by
grinding granulated blast furnace slag conforming to
accepted standards [6-5A(6)] may be used as part
replacement of ordinary Portland cements provided
uniform blending with cement is ensured.
4.3 Aggregates
Aggregates shall comply with the requirements of
accepted standards [6-5 A(7)]. As far as possible
preference shall be given to natural aggregates.
4.3.1 Other types of aggregates such as slag and
crushed overburnt brick or tile, which may be found
suitable with regard to strength, durability of concrete
and freedom from harmful effects may be used for plain
concrete members, but such aggregates should not
contain more than 0.5 percent of sulphates as S0 3 and
should not absorb more than 10 percent of their own
mass of water.
4.3.2 Heavy weight aggregates or light weight
aggregates such as bloated clay aggregates and sintered
fly ash aggregates may also be used provided the
engineer-in-charge is satisfied with the data on the
properties of concrete made with them.
NOTE — Some of the provisions of the Code would require
modification when these aggregates are used; specialist
literature may be consulted for guidance.
4.3.3 Size of Aggregate
The nominal maximum size of coarse aggregate
should be as large as possible within the limits
specified but in no case greater than one-fourth of
the minimum thickness of the member, provided that
the concrete can be placed without difficulty so as to
surround all reinforcement thoroughly and fill the
corners of the form. For most work, 20 mm aggregate
is suitable. Where there is no restriction to the flow
of concrete into sections, 40 mm or larger size may
be permitted. In concrete elements with thin sections,
closely spaced reinforcement or small cover,
consideration should be given to the use of 10 mm
nominal maximum size.
Plums above 160 mm and up to any reasonable size
may be used in plain concrete work up to a maximum
limit of 20 percent by volume of concrete when
specifically permitted by the engineer-in-charge. The
plums shall be distributed evenly and shall be not closer
than 150 mm from the surface.
4.3.3.1 For heavily reinforced concrete members as
in the case of ribs of main beams, the nominal
maximum size of the aggregate should usually be
restricted to 5 mm less than the minimum clear distance
between the main bars or 5 mm less than the minimum
cover to the reinforcement whichever is smaller.
4.3.4 Coarse and fine aggregate shall be batched
separately. All-in-aggregate may be used only where
specifically permitted by the engineer-in-charge.
4.4 Water
Water use for mixing and curing shall be clean and
free from injurious amounts of oils, acids, alkalis, salts,
sugar, organic materials or other substances that may
be deleterious to concrete or steel.
Potable water is generally considered satisfactory
for mixing concrete. As a guide the following
concentrations represent the maximum permissible
values:
a) To neutralize 100 ml sample of water, using
phenolphthalein as an indicator, it should not
require more than 5 ml of 0.02 normal NaOH.
The details of test are given in 7.1 of good
practice [6-5A(8)j.
b) To neutralize 100 ml sample of water, using
mixed indicator, it should not require more
than 25 ml of 0.02 normal H,SO a . The details
2 4
of test shall be as given in 7 of good practice
[6-5A(8)].
c) Permissible limits for solids shall be as given
in Table 1.
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
Table
1 Permissible Limit for Solids
(Clause 4.4)
SI
Tested as per
Permissible Limit,
No.
Max
(1)
(2)
(3)
(4)
i)
Organic
Good practice [6-5A(8)]
200mg/l
ii)
Inorganic
Good practice [6-5A(8)]
3 000 mg/1
in)
Sulphates
(as S0 3 )
Good practice [6-5 A(8)]
400mg/l
iv)
Chlorides
Good practice [6-5A(8)]
2 000 mg/1 for
(as CI)
concrete not
containing embedded
steel and 500 mg/1 for
reinforced concrete
work
v)
Suspended
matter
Good practice [6-5A(8)]
2 000 mg/1
4.4.1 In case of doubt regarding development of
strength, the suitability of water for making concrete
shall be ascertained by the compressive strength and
initial setting time tests specified in 4.4.1.2 and 4.4.1.3.
4.4.1.1 The sample of water taken for testing shall
represent the water proposed to be used for concreting,
due account being paid to seasonal variation. The
sample shall not receive any treatment before testing
other than that envisaged in the regular supply of water
proposed for use in concrete. The sample shall be stored
in a clean container previously rinsed out with similar
water.
4.4.1.2 Average 28 days compressive strength of at
least three 150 mm concrete cubes prepared with water
proposed to be used shall not be less than 90 percent
of the average of strength of three similar concrete
cubes prepared with distilled water. The cubes shall
be prepared, cured and tested in accordance with good
practice [6-5 A(9)].
4.4.1.3 The initial setting time of test block made with
the appropriate cement and the water proposed to be
used shall not be less than 30 min and shall not differ
by ± 30 min from the initial setting time of control test
block prepared with the same cement and distilled
water. The test blocks shall be prepared and tested in
accordance with the good practice [6-5A(10)].
4.4.2 The/?H value of water shall be not less than 6.
4.4.3 Sea Water
Mixing or curing of concrete with sea water is not
recommended because of presence of harmful salts in
sea water. Under unavoidable circumstances sea water
may be used for mixing or curing in plain concrete with
no embedded steel after having given due consideration
to possible disadvantages and precautions including use
of appropriate cement system.
4.4.4 Water found satisfactory for mixing is also
suitable for curing concrete. However, water used for
curing should not produce any objectionable stain or
unsightly deposit on the concrete surface. The presence
of tannic acid or iron compounds is objectionable.
4.5 Chemical Admixtures
4.5.1 Admixture, if used shall comply with accepted
standards [6-5A(ll)]. Previous experience with and
data on such materials should be considered in relation
to the likely standards of supervision and workmanship
to the work being specified.
4.5.2 Admixtures should not impair durability of
concrete nor combine with the constituent to form
harmful compounds nor increase the risk of corrosion
of reinforcement.
4.5.3 The workability, compressive strength and the
slump loss of concrete with and without the use of
admixtures shall be established during the trial mixes
before use of admixtures.
4.5.4 The relative density of liquid admixtures shall
be checked for each drum containing admixtures and
compared with the specified value before acceptance.
4.5.5 The chloride content of admixtures shall be
independently tested for each batch before acceptance.
4.5.6 If two or more admixtures are used
simultaneously in the same concrete mix, data should
be obtained to assess their interaction and to ensure
their compatibility.
4.6 Reinforcement
The reinforcement shall be any of the following
conforming to the accepted standards [6-5A(12)]:
a) Mild steel and medium tensile steel bars.
b) High strength deformed steel bars.
c) Hard-drawn steel wire fabric.
d) Grade A of structural steel.
4.6.1 All reinforcement shall be free from loose mill
scales, loose rust and coats of paints, oil, mud or any
. other substances which niay destroy or reduce bond.
Sand blasting or other treatment is recommended to
clean reinforcement.
4.6.2 Special precautions like coating of
reinforcement may be required for reinforced concrete
elements in exceptional cases and for rehabilitation
of structures. Specialist literature may be referred to
in such cases.
4.6.3 The modulus of elasticity of steel shall be taken
as 200 kN/mm 2 . The characteristic yield strength of
different steel shall be assumed as the minimum yield
stress/0.2 percent proof stress specified in the relevant
Indian Standard.
10
NATIONAL BUILDING CODE OF INDIA
4.7 Storage of Materials
Storage of materials shall be as described in good
practice [6-5A(13)].
5 CONCRETE
5.1 Grades
The concrete shall be in grades designated as per
Table 2.
Table 2 Grades of Concrete
(Clauses 5 A, 8.2.2, 14.1.1 and 35 .1)
Group
Grade
Specified Characteristic
Designation
Compressive Strength of
15ft mm Cube at 28 days in
N/mm 2
(1)
(2)
(3)
Ordinary
M10
10
Concrete
M15
15
M20
20
Standard
M25
25
Concrete
M30
30
M35
35
M40
40
M45
45
M50
50
M55
55
High Strength
M60
60
Concrete
M65
65
M70
70
M75
75
M80
80
NOTES
1 In the designation of concrete mix M refers to the mix and
the number of the specified compressive strength of 150 mm
size cube at 28 days, expressed in N/mm 2 .
2 For concrete of compressive strength greater than M 55,
design parameters given in the standard may not be
applicable and the values may be obtained from specialized
literatures and experimental results.
5.1.1 The characteristic strength is defined as the
strength of material below which not more than 5
percent of the test results are expected to fall.
5.1.2 The minimum grade of concrete for plain and
reinforced concrete shall be as per Table 5.
5.1.3 Concrete of grades lower than those given in
Table 5 may be used for plain concrete constructions,
lean concrete, simple foundations, foundation for
masonry walls and other simple or temporary
reinforced concrete construction.
5.2 Properties of Concrete
5.2.1 Increase of Strength with Age
There is normally a gain of strength beyond 28 days.
The quantum of increase depends upon the grade
and type of cement, curing and environmental
conditions, etc. The design should be based on 28 days
characteristic strength of concrete unless there is an
evidence to justify a higher strength for a particular
structure due to age.
5.2.1.1 For concrete of grade M 30 and above, the
rate of increase of compressive strength with age shall
be based on actual investigations.
5.2.1.2 Where members are subjected to lower direct
load during construction, they should be checked for
stresses resulting from combination of direct load and
bending during construction.
5.2.2 Tensile Strength of Concrete
The flexural and splitting tensile strengths shall be
obtained in accordance with good practice [6-5A(14)].
When the designer wishes to use an estimate of the
tensile strength from the compressive strength, the
following formula may be used:
Flexural strength, / cr = 0.7 ^J^ N/mm 2
where/ ck is the characteristic cube compressive strength
of concrete in N/mm 2 .
5.2.3 Elastic Deformation
The modulus of elasticity is primarily influenced by
the elastic properties of the aggregate and to a lesser
extent by the conditions of curing and age of the
concrete, the mix proportions and the type of cement.
The modulus of elasticity is normally related to the
compressive strength of concrete.
5.2.3.1 The modulus of elasticity of concrete can be
assumed as follows:
E = 5 000j7"
c \ J &
where E is the short-term static modulus of elasticity
in N/mm 2 .
Actual measured values may differ by ±20 percent
from the values obtained from the above expression.
5.2.4 Shrinkage
The total shrinkage of concrete depends upon the
constituents of concrete, size of the member and
environmental conditions. For a given humidity and
temperature, the total shrinkage of concrete is most
influenced by the total amount of water present in the
concrete at the time of mixing and, to a lesser extent,
by the cement content.
5.2.4.1 In the absence of test data, the approximate
value of the total shrinkage strain for design may be
taken as 0.000 3 (for more information, see accepted
standard [6-5 A( 15)]).
5.2.5 Creep of Concrete
Creep of concrete depends, in addition to the factors
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
11
listed in 5.2.4, on the stress in the concrete, age at
loading and the duration of loading. As long as the
stress in concrete does not exceed one-third of its
characteristic compressive strength, creep may be
assumed to be proportional to the stress.
5.2.5.1 In the absence of experimental data and
detailed information on the effect of the variables, the
ultimate creep strain may be estimated from the
following values of creep coefficient (that is, ultimate
creep strain/elastic strain at the age of loading); for
long span structure, it is advisable to determine actual
creep strain, likely to take place;
Age at Loading Creep Coefficient
7 days 2.2
28 days 1.6
1 year 1.1
NOTE — The ultimate creep strain, estimated as described
above does not include the elastic strain.
5.2.6 Thermal Expansion
The coefficient of thermal expansion depends on nature
of cement, the aggregate, the cement content, the
relative humidity and the size of sections.
The value of coefficient of thermal expansion for
concrete with different aggregates may be taken as
below:
(1)
(2)
(3)
Type of Aggregate
Coefficient of Thermal
Expansion for Concrete/°C
Quartzite
1.2 to 1.3 to 10" 5
Sandstone
0.9 to 1.2 to 10" 5
Granite
0.7 to 0.95 to 10 5
Basalt
0.8 to 0.95 to 10- 5
Limestone
0.6 to 0.9 to 10' 5
6 WORKABILITY OF CONCRETE
6.1 The concrete mix proportions chosen should be such
that the concrete is of adequate workability for the
placing conditions of the concrete and can properly be
compacted with the means available. Suggested ranges
of workability of concrete measured in accordance with
good practice [6-5A(16)] are given below:
Placing Conditions
(i)
Slump
Degree of
Workability
(2) (3)
mm
Blinding concrete; Shallow
sections; Pavements using
pavers
Mass concrete; Lightly
reinforced sections in slabs,
Very low See 6.1.1
beams, walls, columns; Floors;
Hand placed pavements; Canal
lining; Strip footings
Heavily reinforced sections in
slabs, beams, walls, columns
Slipform work; Pumped
concrete
Trench fill; in-situ piling
Tremie concrete
Medium 50-100
Medium 75-100
High
100-150
Very high See 6.1.2
Low
25-75
NOTE — For most of the placing conditions, internal vibrators
(needle vibrators) are suitable. The diameter of the needle
shall be determined based on the density and spacing of
reinforcement bars an thickness of sections. For tremie
concrete, vibrators are not required to be used (see
also 13.3).
6.1.1 In the 'very low' category of workability where
strict control is necessary, for example, pavement
quality concrete, measurement of workability by
determination of compacting factor will be more
appropriate than slump (see accepted standard
[6-5A(16)]) and a value of compacting factor of 0.75
to 0,80 is suggested.
6.1.2 In the 'very high' category of workability,
measurement of workability by determination of flow
will be appropriate (see accepted standard [6-5A(17)] ).
7 DURABILITY OF CONCRETE
7.1 General
A durable concrete is one that performs satisfactorily
in the working environment during its anticipated
exposure conditions during service. The materials and
mix proportions specified and used should be such as
to maintain its integrity and, if applicable, to protect
embedded metal from corrosion.
7.1.1 One of the main characteristics influencing the
durability of concrete is its permeability to the ingress
of water, oxygen, carbon dioxide, chloride, sulphate and
other potentially deleterious substances. Impermeability
is governed by the constituents and workmanship used
in making the concrete. With normal- weight aggregates
a suitably low permeability is achieved by having an
adequate cement content, sufficiently low free water/
cement ratio, by ensuring complete compaction of the
concrete, and by adequate curing.
The factors influencing durability include:
a) the environment;
b) the cover to embedded steel;
c) the type and quality of constituent materials;
d) the cement content and water/cement ratio of
the concrete;
12
NATIONAL BUILDING CODE OF INDIA
f)
workmanship, to obtain full compaction and
efficient curing; and
the shape and size of the member.
The degree of exposure anticipated for the concrete
during its service life together with other relevant
factors relating to mix composition, workmanship,
design and detailing should be considered. The
concrete mix to provide adequate durability under these
conditions should be chosen taking account of the
accuracy of current testing regimes for control and
compliance as described in this Section.
7.2 Requirements for Durability
7.2.1 Shape and Size of Member
The shape or design details of exposed structures
should be such as to promote good drainage of water
and to avoid standing pools and rundown of water.
Care should also be taken to minimize any cracks that
may collect or transmit water. Adequate curing is
essential to avoid the harmful effects of early loss of
moisture (see 12.5). Member profiles and their
intersections with other members shall be designed and
detailed in a way to ensure easy flow of concrete and
proper compaction during concreting.
Concrete is more vulnerable to deterioration due to
chemical or climatic attack when it is in thin sections,
in sections under hydrostatic pressure from one side
only, in partially immersed sections and at corners and
edges of elements. The life of the structure can be
lengthened by providing extra cover to steel, by
chamfering the corners or by using circular cross-
sections or by using surface coatings which prevent or
reduce the ingress of water, carbon dioxide or
aggressive chemicals.
7.2.2 Exposure Conditions
7.2.2.1 General environment
The general environment to which the concrete will
be exposed during its working life is classified into
five levels of severity, that is, mild, moderate, severe,
very severe and extreme as described in Table 3.
7.2.2.2 Abrasive
Specialist literatures may be referred to for durability
requirements of concrete surfaces exposed to abrasive
action, for example, in case of machinery and metal
tyres.
7.2.2.3 Freezing and thawing
Where freezing and thawing actions under wet
conditions exist, enhanced durability can be obtained
by the use of suitable air entraining admixtures. When
concrete lower than grade M 50 is used under these
conditions, the mean total air content by volume of
the fresh concrete at the time of delivery into the
construction should be:
Nominal Maximum Size
Aggregate (mm)
20
40
Entrained Air
Percentage
5±1
4±1
Since air entrainment reduces the strength, suitable
adjustments may be made in the mix design for
achieving required strength.
7.2.2.4 Exposure to sulphate attack
Table 4 gives recommendations for the type of cement,
maximum free water/cement ratio and minimum
cement content, which are required at different sulphate
Table 3 Environmental Exposure Conditions
{Clauses 1 22 .1 and 3432)
SI No.
Environment
(1)
(2)
i)
Mild
ii)
Moderate
iii)
Severe
iv) Very Severe
v) Extreme
Exposure Conditions
(3)
Concrete surfaces protected against weather or aggressive conditions, except those situated in coastal
area.
Concrete surfaces sheltered from severe rain or freezing whilst wet.
Concrete exposed to condensation and rain.
Concrete continuously under water.
Concrete in contact or buried under non-aggressive soil/ground water.
Concrete surfaces sheltered from saturated salt air in coastal area.
Concrete surfaces exposed to severe rain, alternate wetting and drying or occasional freezing whilst wet
or severe condensation.
Concrete completely immersed in sea water.
Concrete exposed to coastal environment.
Concrete surfaces exposed to sea water spray, corrosive fumes or severe freezing conditions whilst wet.
Concrete in contact with or buried under aggressive sub-soil/ground water.
Surface of members in tidal zone.
Members in direct contact with liquid/solid aggressive chemicals.
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
13
Table 4 Requirements for Concrete Exposed to Sulphate Attack
(Clauses 1.2.2 A and 8.1.2)
St Class
No.
Concentration of Sulphates,
Expressed as SO3
Type of Cement
In Soil
In Ground
Water
Total SO3
S0 3 in2:l
Water: Soil
Extract
Percent
g*
g*
ID
(2)
(3)
(4)
(5)
i)
1
Traces
(<0.2)
Less
than 1.0
Less
than 0.3
Dense, Fully Compacted
Concrete. Made with 20 mm
Nomina] Maximum Size
Aggregates in Accordance
with Accepted Standard
[6-5A(18)]
(6)
Minimum Maximum Free
Cement Content Water-Cement
kg/m 3 Ratio
(7) (8)
ii) 2 0.2 to 0.5 1 .0 to 1 .9 0.3 to 1 .2
iii) 3 0.5 to 1.0 1.9 to 3.1 1.2 to 2.5
iv) 4 1.0 to 2.0 3.1 to 5.0 2.5 to 5.0
v) 5 More More More
than 2.0 than 5.0 than 5.0
Ordinary Portland cement or Portland slag 280
cement or Portland pozzolana cement
Ordinary Portland cement or Portland slag 330
cement or Portland pozzolana cement
Supersulphated cement or sulphate resisting 310
Portland cement
Supersulphated cement or sulphate resisting 330
Portland cement
Portland pozzolana cement or Portland slag 350
cement
Supersulphated or sulphate resisting Portland 370
cement
Sulphate resisting Portland cement or 400
supersulphated cement with protective coatings
0.55
0.50
0.50
0.50
0.45
0.45
0.40
NOTES
1 Cement content given in this table is irrespective of grades of cement.
2 Use of supersulphated cement is generally restricted where the prevailing temperature is above 40°C.
3 Supersulphated cement gives an acceptable life provided that the concrete is dense and prepared with a water-cement ratio of 0.4
or less, in mineral acids, down to pH 3.5.
4 The cement contents given in col 6 of this table are the minimum recommended. For S0 3 contents near the upper limit of any class,
cement contents above these minimum are advised.
5 For severe conditions, such as thin sections under hydrostatic pressure on one side only and sections partly immersed, considerations
should be given to a further reduction of water-cement ratio.
6 Portland slag cement conforming to accepted standard [6-5A(3)J with slag content more than 50 percent exhibits better sulphate
resisting properties.
7 Where chloride is encountered along with sulphates in soil or ground water, ordinary Portland cement with C 3 A content from 5
to 8 percent shall be desirable to be used in concrete, instead of sulphate resisting cement. Alternatively, Portland slag cement
conforming to accepted standard [6-5 A(3)J having more than 50 percent slag or a blend of ordinary Portland cement and slag may be
used provided sufficient information is available on performance of such blended cements in these conditions.
concentrations in near-neutral ground water having pH
of 6 to 9.
For the very high sulphate concentrations in Class 5
conditions, some form of lining such as polyethylene
or polychloroprene sheet; or surface coating based on
asphalt, chlorinated rubber, epoxy; or polyurethane
materials should also be used to prevent access by the
sulphate solution.
7.2.3 Requirement of Concrete Cover
7.2.3.1 The protection of the steel in concrete against
corrosion depends upon an adequate thickness of good
quality concrete.
7.2.3.2 The nominal coyer to the reinforcement shall
be provided as per 25.4.
7.2.4 Concrete Mix Proportions
7.2.4.1 General
The free water-cement ratio is an important factor in
governing the durability of concrete and should always
be the lowest value. Appropriate values for minimum
cement content and the maximum free water-cement
ratio are given in Table 5 for different exposure
conditions. The minimum cement content and
maximum water-cement ratio apply to 20 mm nominal
14
NATIONAL BUILDING CODE OF INDIA
Table 5 Minimum Cement Content, Maximum Water-Cement Ratio and Minimum Grade
of Concrete for Different Exposures with Normal Weight Aggregates of 20 mm
Nominal Maximum Size
(Clauses 5.1.2, 5.1.3, 7.2.4.1 and 8.1.2)
SI No.
Exposure
Plain Concrete
Reinforced Concrete
_^v_
^Xta^
Minimum
Maximum Free
Minimum Grade
Minimum
Maximum Free
Minimum Grade
Cement Content
Water-Cement
of Concrete
Cement Content
Water-Cement
of Concrete
kg/m 3
Ratio
kg/m 3
Ratio
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
i)
Mild
220
0.60
—
300
0.55
M20
ii)
Moderate
240
0.60
M15
300
0.50
M25
iii)
Severe
250
0.50
M20
320
0.45
M30
iv)
Very Severe
260
0.45
M20
340
0.45
M35
v)
Extreme
280
0.40
M25
360
0.40
M40
NOTES
1 Cement content prescribed in this table is irrespective of the grades of cement and it is inclusive of additions mentioned in 4.2. The
additions such as fly ash or ground granulated blast furnace slag may be taken into account in the concrete composition with respect
to the cement content and water-cement ratio if the suitability is established and as long as the maximum amounts taken into account
do not exceed the limit of pozzolana and slag specified in accordance with accepted standard [6-5A(19)].
2 Minimum grade for plain concrete under mild exposure condition is not specified.
maximum size aggregate. For other sizes of aggregate
they should be changed as given in Table 6.
Table 6 Adjustments to Minimum Cement
Contents for Aggregates Other Than 20 mm
Nominal Maximum Size
(Clause 7.2.4.1)
SI
Nominal Maximum
Adjustments to Minimum Cement
No.
Aggregate
Size
Contents Given in Table 5
mm
kg/m 3
(1)
(2)
(3)
i)
10
+ 40
ii)
20
iii)
40
-30
7.2.4.2 Maximum cement content
Cement content not including fly ash and ground
granulated blast furnace slag in excess of 450 kg/m 3
should not be used unless special consideration has
been given in design to the increased risk of cracking
due to drying shrinkage in thin sections, or to early
thermal cracking and to the increased risk of damage
due to alkali silica reactions.
7.2.5 Mix Constituents
7.2.5.1 General
For concrete to be durable, careful selection of the mix
and materials is necessary, so that deleterious
constituents do not exceed the limits.
7.2.5.2 Chlorides in concrete
Whenever there is chloride in concrete there is an
increased risk of corrosion of embedded metal. The
higher the chloride content, or if subsequently exposed
to warm moist conditions, the greater the risk of
corrosion. All constituents may contain chlorides and
concrete may be contaminated by chlorides from the
external environment. To minimize the chances of
deterioration of concrete from harmful chemical salts,
the levels of such harmful salts in concrete coming
from concrete materials, that is, cement, aggregates
water and admixtures, as well as by diffusion from the
environment should be limited. The total amount of
chloride content (as CI) in the concrete at the time of
placing shall be as given in Table 7.
The total acid soluble chloride content should be
calculated from the mix proportions and the measured
chloride contents of each of the constituents. Wherever
possible, the total chloride content of the concrete
should be determined.
Table 7 Limits of Chloride Content of Concrete
(Clause 7.2.5.2)
SI
Type or Use of Concrete
Maximum Total Acid
No,
Soluble Chloride
Content Expressed as
kg/m 3 of Concrete
(1)
(2)
(3)
i)
Concrete containing metal and
steam cured at elevated
temperature and prestressed
concrete
0.4
ii)
Reinforced concrete or plain
concrete containing embedded
metal
0.6
iii)
Concrete not containing
embedded metal or any material
requiring protection from chloride
3.0
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5 A PLAIN AND REINFORCED CONCRETE
15
7.2.5.3 Sulphates in concrete
Sulphates are present in most cements and in some
aggregates; excessive amounts of water-soluble
sulphate from these or other mix constituents can cause
expansion and disruption of concrete. To prevent this,
the total water-soluble sulphate content of the concrete
mix, expressed as S0 3 * should not exceed 4 percent by
mass of the cement in the mix. The sulphate content
should be calculated as the total from the various
constituents of the mix.
The 4 percent limit does not apply to concrete made
with supersulphated cement complying with accepted
standard [6-5A(20)].
7.2.5.4 Alkali-aggregate reaction
Some aggregates containing particular varieties of
silica may be susceptible to attack by alkalis (Na 2
and K 2 0) originating from cement or other sources,
producing an expansive reaction which can cause
cracking and disruption of concrete. Damage to
concrete from this reaction will normally only occur
when all the following are present together:
a) A high moisture level, within the concrete;
b) A cement with high alkali content, or another
source of alkali; and
c) Aggregate containing an alkali reactive
constituent.
Where the service records of particular cement/
aggregate combination are well established, and do not
include any instances of cracking due to alkali-
aggregate reaction, no further precautions should be
necessary. When the materials are unfamiliar,
precautions should take one or more of the following
form:
a) Use of non-reactive aggregate from alternate
sources.
b) Use of low alkali ordinary Portland cement
having total alkali content not more than 0.6
percent (as Na 2 equivalent).
Further advantage can be obtained by use of
fly ash (Grade 1) conforming to accepted
standard [6-5 A(5)] or granulated blastfurnace
slag conforming to accepted standard
[6-5A(5)] as part replacement of ordinary
Portland cement (having total alkali
content as Na 2 equivalent not more than
0.6 percent), provided fly ash content is at
least 20 percent or slag content is at least
50 percent.
c) Measures to reduce the degree of saturation
of the concrete during service, such as use of
impermeable membranes.
d) Limiting the cement content in the concrete
mix and thereby limiting total alkali content
in the concrete mix. For more guidance
specialist literatures may be referred.
7.2.6 Concrete in Aggressive Soils and Water
7.2.6.1 General
The destructive action of aggressive waters on concrete
is progressive. The rate of deterioration decreases as
the concrete is made stronger and more impermeable,
and increases as the salt content of the water increases.
Where structures are only partially immersed or are in
contact with aggressive soils or waters on one side only,
evaporation may cause serious concentrations of salts
with subsequent deterioration, even where the original
salt content of the soil or water is not high.
NOTE — Guidance regarding requirements for concrete
exposed to sulphate attack is given in 7.2.2.4.
7.2.6.2 Drainage
At sites where alkali concentrations are high or may
become very high, the ground water should be lowered
by drainage so that it will not come into direct contact
with the concrete.
Additional protection may be obtained by the use of
chemically resistant stone facing or a layer of plaster
of Paris covered with suitable fabric, such as jute
thoroughly impregnated with bituminous material.
7.2.7 Compaction, Finishing and Curing
Adequate compaction without segregation should be
ensured by providing suitable workability and by
employing appropriate placing and compacting
equipment and procedures. Full compaction is
particularly important in the vicinity of construction
and movement joints and of embedded water bars and
reinforcement.
Good finishing practices are essential for durable
concrete.
Overworking the surface and the addition of water/
cement to aid in finishing should be avoided; the
resulting laitance will have impaired strength and
durability and will be particularly vulnerable to
freezing and thawing under wet conditions.
It is essential to use proper and adequate curing
techniques to reduce the permeability of the concrete
and enhance its durability by extending the hydration
of the cement, particularly in its surface zone (see 12.5).
7.2.8 Concrete in Sea-water
Concrete in sea-water or exposed directly along the
sea-coast shall be at least M 20 Grade in the case of
plain concrete and M 30 in case of reinforced concrete.
16
NATIONAL BUILDING CODE OF INDIA
The use of slag or pozzolana cement is advantageous
under such conditions.
7.2.8.1 Special attention shall be given to the design
of the mix to obtain the densest possible concrete; slag,
broken brick, soft limestone, soft sandstone, or other
porous or weak aggregates shall not be used.
7.2.8.2 As far as possible, preference shall be given
to precast members unreinforced, well-cured and
hardened, without sharp corners, and having trowel-
smooth finished surfaces free from crazing, cracks or
other defects; plastering should be avoided.
7.2.8.3 No construction joints shall be allowed within
600 mm below low water-level or within 600 mm of
the upper and lower planes of wave action. Where
unusually severe conditions or abrasion are anticipated,
such parts of the work shall be protected by bituminous
or silico-flouride coatings or stone facing bedded with
bitumen.
7.2.8.4 In reinforced concrete structures, care shall be
taken to protect the reinforcement from exposure to
saline atmosphere during storage, fabrication and use.
It may be achieved by treating the surface of
reinforcement with cement wash or by suitable
methods.
8 CONCRETE MIX PROPORTIONING
8.1 Mix Proportion
The mix proportion shall be selected to ensure the
workability of the fresh concrete and when concrete is
hardened, it shall have the required strength, durability
and surface finish.
8.1.1 The determination of the proportions of cement,
aggregates and water to attain the required strengths
shall be made as follows:
a) By designing the concrete mix; such concrete
shall be called 'Design mix concrete', or
b) By adopting nominal concrete mix; such
concrete shall be called 'Nominal mix
concrete' .
Design mix concrete is preferred to nominal mix. If
design mix concrete cannot be used for any reason on
the work for grades of M 20 or lower, nominal mixes
may be used with the permission of engineer-in-charge,
which, however, is likely to involve a higher cement
content.
8.1.2 Information Required
In specifying a particular grade of concrete, the
following information shall be included:
a) Type of mix, that is, design mix concrete or
nominal mix concrete;
b) Grade designation;
c) Type of cement;
d) Maximum nominal size of aggregate;
e) Minimum cement content (for design mix
concrete);
f) Maximum water-cement ratio;
g) Workability;
h) Mix proportion (for nominal mix concrete);
j) Exposure conditions as per Tables 4 and 5;
k) Maximum temperature of concrete at the time
of placing;
m) Method of placing; and
n) Degree of supervision.
8.1.2.1 In appropriate circumstances, the following
additional information may be specified;
a) Type of aggregate,
b) Maximum cement content, and
c) Whether an admixture shall or shall not be
used and the type of admixture and the
condition of use.
8.2 Design Mix Concrete
8.2.1 As the guarantor of quality of concrete used in
the construction, the constructor shall carry out the mix
design and the mix so designed (not the method of
design) shall be approved by the employer within the
limitations of parameters and other stipulations laid
down by this standard.
8.2.2 The mix shall be designed to produce the grade
of concrete having the required workability and a
characteristic strength not less than appropriate values
given in Table 2. The target mean strength of concrete
mix should be equal to the characteristic strength plus
1.65 times the standard deviation.
8.2.3 Mix design done earlier not prior to one year
may be considered adequate for later work provided
there is no change in source and the quality of the
materials.
8.2.4 Standard Deviation
The standard deviation for each grade of concrete shall
be calculated, separately.
8.2.4.1 Standard deviation based on test strength of
sample
a) Number of test results of samples — The total
number of test strength of samples required
to constitute an acceptable record for
calculation of standard deviation shall be not
less than 30. Attempts should be made to
obtain the 30 samples, as early as possible,
when a mix is used for the first time.
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
17
b) In case of significant changes in concrete —
When significant changes are made in the
production of concrete batches (for example
changes in the materials used, mix design,
equipment or technical control), the standard
deviation value shall be separately calculated
for such batches of concrete.
c) Standard deviation to be brought up to date
— The calculation of the standard deviation
shall be brought up to date after every change
of mix design.
8.2.4.2 Assumed standard deviation
Where sufficient test results for a particular grade of
concrete are not available, the value of standard
deviation given in Table 8 may be assumed for design
of mix in the first instance. As soon as the results of
samples are available, actual calculated standard
deviation shall be used and the mix designed properly.
However, when adequate past records for a similar
grade exist and justify to the designer a value of
standard deviation different from that shown in Table
8, it shall be permissible to use that value.
Table 8 Assumed Standard Deviation
{Clause S2A2 and Table 11)
Grade of Concrete Assumed Standard Deviation
N/mm 2
(i)
(2)
M 10 1
M 15 J
3.5
M20 *
M25
4.0
M 30 ^
M35
M40
> 5.0
M45
M50 j
NOTE — The above values correspond to the site control
having proper storage of cement; weigh batching of all
materials; controlled addition of water; regular checking of all
materials, aggregate gradings and moisture content; and
periodical checking of workability and strength. Where there
is deviation from the above the values given in the above table
shall be increased by 1 N/mm 2 ,
8.3 Nominal Mix Concrete
Nominal mix concrete may be used for concrete of M 20
or lower. The proportions of materials for nominal mix
concrete shall be in accordance with Table 9.
8.3.1 The cement content of the mix specified in
Table 9 for any nominal mix shall be proportionately
increased if the quantity of water in a mix has to be
increased to overcome the difficulties of placement and
compaction, so that the water-cement ratio as specified
is not exceeded.
9 PRODUCTION OF CONCRETE
9.1 Quality Assurance Measures
9.1.1 In order that the properties of the completed
structure be consistent with the requirements and the
assumptions made during the planning and the design,
adequate quality assurance measures shall be taken.
The construction should result in satisfactory strength,
serviceability and long-term durability so as to lower
the overall life-cycle cost. Quality assurance in
construction activity relates to proper design, use of
adequate materials and components to be supplied by
the producers, proper workmanship in the execution
of works by the contractor and ultimately proper
care during the use of structure including timely
maintenance and repair by the owner.
9.1.2 Quality assurance measures are both technical
and organizational. Some common cases should be
specified in a general Quality Assurance Plan which
shall identify the key elements necessary to provide
fitness of the structure and the means by which they
are to be provided and measured with the overall
purpose to provide confidence that the realized project
will work satisfactorily in service fulfilling intended
needs. The job of quality control and quality assurance
would involve quality audit of both the inputs as well
as the outputs. Inputs are in the form of materials for
concrete; workmanship in all stages of batching,
mixing, transportation, placing, compaction and
curing; and the related plant, machinery and
equipments; resulting in the output in the form of
concrete in place. To ensure proper performance, it is
necessary that each step in concreting which will be
covered by the next step is inspected as the work
proceeds {see also 16).
9.1.3 Each party involved in the realization of a project
should establish and implement a Quality Assurance
Plan, for its participation in the project. Supplier' s and
subcontractor's activities shall be covered in the plan.
The individual Quality Assurance Plans shall fit into
the general Quality Assurance Plan. A Quality
Assurance Plan shall define the tasks and responsibilities
of all persons involved, adequate control and checking
procedures, and the organization and maintaining
adequate documentation of the building process and
its results. Such documentation should generally
include:
a) test reports and manufacturer' s certificate for
materials, concrete mix design details;
b) pour cards for site organization and clearance
for concrete placement;
c) record of site inspection of workmanship,
field tests;
d) non-conformance reports, change orders;
18
NATIONAL BUILDING CODE OF INDIA
1 able 9 Proportions for Nominal Mix Concrete
{Clauses 8.3 and 8.3.1)
Grade of
Total Quantity of Dry Aggregates by
Proportion of Fine Aggregate to
Quantity of Water per
Concrete
Mass per 50 kg of Cement, to be
Coarse Aggregate
50 kg of Cement,
laivcii aa uic ouni ui uic uiuiriuuai
/l TkM \
Max
Masses of Fine and Coarse
Aggregates, kg,
Max
(1)
(2)
(3)
(4)
M 5
800
vjv " v, " u ;
60
M7.5
625
limit of 1:
: IV2 and a lower limit of 1:2V£
45
M 10
480
34
M 15
330
32
M20
250
30
NOTE — The proportion of the fine to coarse aggregates should be adjusted from upper limit to lower limit progressively as the
grading of fine aggregates becomes finer and the maximum size of coarse aggregate becomes larger. Graded coarse aggregate shall be
used.
Example
For an average grading of fine aggregate (that is, Zone II of Table 4 of IS 3S3), the proportions shaii be I:Iv2, 1:2 and I:2v2 for
maximum size of aggregates 10 mm, 20 mm and 40 mm respectively.
e) quality control charts; and
i) statistical anaWsis.
NOTE — Quality control charts are recommended
wherever the concrete is in continuous production over
considerable period.
9.2 Batching
To avoid confusion and error in batching, consideration
should be given to using the smallest practical number
of different concrete mixes on any site or in any one
plant. In batching concrete, the quantity of both cement
and aggregate shall be determined by mass; admixture,
if solid, by mass; liquid admixture may, however, be
measured in volume or mass; water shall be weighed
or measured by volume in a calibrated tank (see also
accepted standard [6-5A(21)l ).
Ready-mixed concrete supplied by ready-mixed
concrete plant shall be preferred. For large and medium
project sites the concrete shall be sourced from ready-
mixed concrete plants or from on site or off site
batching and mixing plants (see also accepted standard
[6-5A(21)]).
9.2.1 Except where it can be shown to the satisfaction
of the engineer-in-charge that supply of properly
graded aggregate of uniform quality can be maintained
over a period of work, the grading of aggregate should
be controlled by obtaining the coarse aggregate in
different sizes and blending them in the right
proportions when required, the different sizes being
stocked in separate stock-piles. The material should
be stock-piled for several hours preferably a day before
use. The grading of coarse and fine aggregate should
be checked as frequently as possible, the frequency
for a given job being determined by the engineer-in-
charge to ensure that the specified grading is
maintained.
9.2.2 The accuracy of the measuring equipment shall
be within ± 2 percent of the quantity of cement being
measured and within ± 3 percent of the quantity of
aggregate, admixtures and water being measured.
9.2.3 Proportion/Type and grading of aggregates shall
be made by trial in such a way so as to obtain densest
possible concrete. All ingredients of the concrete
should be used by mass only.
9.2.4 Volume batching may be allowed only where
weigh-batching is not practical and provided accurate
bulk densities of materials to be actually used in
concrete have earlier been established. Allowance for
bulking shall be made in accordance with accepted
standard [6-5A(23)]. The mass volume relationship
should be checked as frequently as necessary, the
frequency for the given job being determined by
engineer-in-charge to ensure that the specified grading
is maintained.
9.2.5 It is important to maintain the water-cement ratio
constant at its correct value. To this end, determination
of moisture contents in both fine and coarse aggregates
shall be made as frequently as possible, the frequency
for a given job being determined by the engineer-in-
charge according to weather conditions. The amount
of the added water shall be adjusted to compensate for
any observed variations in the moisture contents. For
the determination of moisture content in the aggregates,
PART 6 STRUCTURAL DESIGN — SECTION 5 CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
IV
accepted standard [6-5A(23)] may be referred to. To
allow for the variation in mass of aggregate due to
variation in their moisture content, suitable adjustments
in the masses of aggregates shall also be made. In the
absence of exact data, only in the case of nominal
mixes, the amount of surface water may be estimated
from the values given in Table 10.
Table 10 Surface Water Carried by Aggregate
(Clause 9.2,5)
SI
No.
Aggregate
(2)
Approximate Quantity
of Surface Water
0)
Percent by
Mass
(3)
1/m 2
(4)
i) Veiy wet sand 7.5
ii) Moderately wet sand 5.0
iii) Moist sand 2.5
iv) Moist gravel or crushed rock 1} 1 .25 - 2.5
1} Coarser the aggregate, less the water it will carry.
120
80
40
20-40
9.2.6 No substitutions in materials used on the work
or alterations in the established proportions, except as
permitted in 9.2.4 and 9.2.5 shall be made without
additional tests to show that the quality and strength
of concrete are satisfactory.
9.3 Mixing
Concrete shall be mixed in a mechanical mixer. The
mixer should comply with accepted standard
[6-5A(24)]. The mixers shall be fitted with water
measuring (metering) devices. The mixing shall be
continued until there is a uniform distribution of the
materials and the mass is uniform in colour and
consistency. If there is segregation after unloading from
the mixer, the concrete should be re-mixed.
9.3.1 For guidance, the mixing time shall be at least 2
min. For other types of more efficient mixers,
manufacturers recommendations shall be followed; for
hydrophobic cement it may be decided by the engineer-
hvcharge.
9.3.2 Workability should be checked at frequent
intervals (see accepted standard [6-5A(16)] ).
9.3.3 Dosages of retarders, plasticizers and
superplasticizers shall be restricted to 0.5, 1.0 and 2.0
percent respectively by weight of cementitious
materials, unless a higher value is agreed upon between
the manufacturer and the constructor based on
performance test.
10 FORMWORK
10.1 General
The formwork shall be designed and constructed so as
to remain sufficiently rigid during placing and
compaction of concrete and shall be such as to prevent
loss of slurry from the concrete. For further details
regarding design, detailing, etc, reference may be made
to good practice [6-5A(25)]. The tolerances on the
shapes, lines and dimensions shown in the drawing
shall be within the limits given below:
a) Deviation from
specified dimensions
of cross-section of
columns and beams
+12
-6
mm
b)
Deviation from
dimensions of
footings
1) Dimensions
in plan
2) Eccentricity
+50.
-12
mm
3) Thickness
0.02 times the width
of the footing in the
direction of deviation
but not more than
50 mm
± 0.05 times the
specified thickness
These tolerances apply to concrete dimensions only,
and not to positioning of vertical reinforcing steel or
dowels.
10.2 Cleaning and Treatment of Formwork
All rubbish, particularly, chippings, shavings and
sawdust shall be removed from the interior of the forms
before the concrete is placed. The face of formwork in
contact with the concrete shall be cleaned and treated
with form release agent. Release agents should be
applied so as to provide a thin uniform coating to the
forms without coating the reinforcement.
10.3 Stripping Time
Forms shall not be released until the concrete has
achieved a strength of at least twice the stress to which
the concrete may be subjected at the time of removal
of formwork. The strength referred to shall be that of
concrete using the same cement and aggregates and
admixture, if any, with the same proportions and cured
under conditions of temperature and moisture similar
to those existing on the work.
10.3.1 While the above criteria of strength shall be
the guiding factor for removal of formwork, in normal
circumstances where ambient temperature does not
fall below 15°C and where ordinary Portland cement
is used and adequate curing is done, following striking
period may deem to satisfy the guideline given
in 10.3:
20
NATIONAL BUILDING CODE OF INDIA
Type of Formwork
Minimum Period
Before Striking
Formwork
a)
Vertical formwork to
columns, walls, beams
16-24 h
b)
Soffit formwork to slabs
(Props to be refixed
immediately after removal
of formwork)
3 days
c)
Soffit formwork to beams
(Props to be refixed
immediately after removal
of formwork)
7 days
d)
Props to slabs:
1) Spanning up to 4.5 m
7 days
2) Spanning over 4.5 m
14 days
e)
Props to beams and
arches:
1 ) Spanning up to 6 m
14 days
2) Spanning over 6 m
21 days
For other cements and lower temperature, the stripping
time recommended above may be suitably modified.
10.3.2 The number of props left under, their sizes and
disposition shall be such as to be able to safely carry
the full dead load of the slab, beam or arch as the case
may be together with any live load likely to occur
during curing or further construction.
10.3.3 Where the shape of the element is such that the
formwork has re-entrant angles, the formwork shall
be removed as soon as possible after the concrete has
set, to avoid shrinkage cracking occurring due to the
restraint imposed.
11 ASSEMBLY OF REINFORCEMENT
11.1 Reinforcement shall be bent and fixed in
accordance with procedure specified in good practice
[6-5A(26)]. The high strength deformed steel bars
should not be re-bent or straightened without the
approval of engineer-in-charge.
Bar bending schedules shall be prepared for all
reinforcement work.
1 1.2 All reinforcement shall be placed and maintained
in the position shown in the drawings by providing
proper cover blocks, spacers, supporting bars, etc.
11.2.1 Crossing bars should not be tack-welded for
assembly of reinforcement unless permitted by
engineer-in-charge.
11.3 Placing of Reinforcement
Rough handling, shock loading (prior to embedment)
and the dropping of reinforcement from a height should
be avoided. Reinforcement should be secured against
displacement outside the specified limits.
11.3.1 Tolerances on Placing of Reinforcement
Unless otherwise specified by engineer-in-charge, the
reinforcement shall be placed within the following
tolerances:
a) for effective depth 200 mm or less ± 10 mm
b) for effective depth more than 200 mm ±15 mm
12.3.2 Tolerance for Cover
Unless specified otherwise, actual concrete cover
should not deviate from the required nominal cover
u +10
by _ q mm.
Nominal cover as given in 25.4.1 should be specified
to all steel reinforcement including links. Spacers
between the links (or the bars where no links exist)
and the formwork should be of the same nominal size
as the nominal cover.
Spacers, chairs and other supports detailed on
drawings, together with such other supports as may be
necessary, should be used to maintain the specified
nominal cover to the steel reinforcement. Spacers or
chairs should be placed at a maximum spacing of 1 m
and closer spacing may sometimes be necessary.
Spacers, cover blocks should be of concrete of same
strength or PVC.
11.4 Welded Joints or Mechanical Connections
Welded joints or mechanical connections in
reinforcement may be used but in all cases of important
connections, test shall be made to prove that the joints
are of the full strength of bars connected. Welding of
reinforcements shall be done in accordance with good
practice [6-5 A(27)].
11.5 Where reinforcement bars up to 12 mm for high
strength deformed steel bars and up to 16 mm for mild
steel bars are bent aside at construction joints and
afterwards bent back into their original positions, care
should be taken to ensure that at no time is the radius
of the bend less than 4 bar diameters for plain mild
steel or 6 bar diameters for deformed bars. Care shall
also be taken when bending back bars, to ensure that
the concrete around the bar is not damaged beyond
the band.
11.6 Reinforcement should be placed and tied in such
a way that concrete placement be possible without
segregation of the mix. Reinforcement placing should
allow compaction by immersion vibrator. Within the
concrete mass, different types of metal in contact
should be avoided to ensure that bimetal corrosion does
not take place.
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
21
12 TRANSPORTING, PLACING, COMPACTION
AND CURING
12.1 Transporting and Handling
After mixing, concrete shall be transported to the
form work as rapidly as possible by methods which will
prevent the segregation or loss of any of the ingredients
or ingress of foreign matter or water and maintaining
the required workability.
12.1.1 During hot or cold weather, concrete shall be
transported in deep containers. Other suitable methods
to reduce the loss of water by evaporation in hot
weather and heat loss in cold weather may also be
adopted,
12.2 Placing
The concrete shall be deposited as nearly as practicable
in its final position to avoid rehandling. The concrete
shall be placed and compacted before initial setting of
concrete commences and should not be subsequently
disturbed. Methods of placing should be such as to
preclude segregation. Care should be taken to avoid
displacement of reinforcement or movement of
formwork. As a general guidance, the maximum
permissible free fall of concrete may be taken as 1 .5 m.
12.3 Compaction
Concrete should be thoroughly compacted and fully
worked around the reinforcement, around embedded
fixtures and into corners of the formwork.
12.3.1 Concrete shall be compacted using mechanical
vibrators complying with accepted standard
[6-5A(28)]. Over vibration and under vibration of
concrete are harmful and should be avoided. Vibration
of very wet mixes should also be avoided.
Whenever vibration has to be applied externally, the
design of formwork and the disposition of vibrators
should receive special consideration to ensure efficient
compaction and to avoid surface blemishes.
12.4 Construction Joints and Cold Joints
Joints are a common source of weakness and, therefore,
it is desirable to avoid them. If this is not possible,
their number shall be minimized. Concreting shall be
carried out continuously up to construction joints, the
position and arrangement of which shall be indicated
by the designer. Construction joints should comply
with accepted standard [6-5A(29)].
Construction joints shall be placed at accessible
locations to permit cleaning out of laitance, cement
slurry and unsound concrete, in order to create rough/
uneven surface. It is recommended to clean out laitance
and cement slurry by using wire brush on the surface
of joint immediately after initial setting of concrete
and to clean out the same immediately thereafter. The
prepared surface should be in a clean saturated surface
dry condition when fresh concrete is placed, against
it.
In the case of construction joints at locations where
the previous pour has been cast against shuttering the
recommended method of obtaining a rough surface for
the previously poured concrete is to expose the
aggregate with a high pressure water jet or any other
appropriate means.
Fresh concrete should be thoroughly vibrated near
construction joints so that mortar from the new concrete
flows between large aggregates and develop proper
bond with old concrete.
Where high shear resistance is required at the
construction joints, shear keys may be provided.
Sprayed curing membranes and release agents should
be thoroughly removed from joint surfaces.
12.5 Curing
Curing is the process of preventing the loss of moisture
from the concrete whilst maintaining a satisfactory
temperature regime. The prevention of moisture loss
from the concrete is particularly important if the water-
cement ratio is low, if the cement has a high rate of
strength development, if the concrete contains
granulated blast furnace slag or pulverized fuel ash.
The curing regime should also prevent the development
of high temperature gradients within the concrete.
The rate of strength development at early ages of
concrete made with supersulphated cement is
significantly reduced at lower temperatures.
Supersulphated cement concrete is seriously affected
by inadequate curing and the surface has to be kept
moist for at least seven days.
12.5.1 Moist Curing
Exposed surfaces of concrete shall be kept continuously
in a damp or wet condition by ponding or by covering
with a layer of sacking, canvas, hessian or similar
materials and kept constantly wet for at least seven
days from the date of placing concrete in case of
ordinary Portland Cement and at least 10 days where
mineral admixtures or blended cements are used. The
period of curing shall not be less than 10 days for
concrete exposed to dry and hot weather conditions.
In the case of concrete where mineral admixtures or
blended cements are used, it is recommended that
above minimum periods may be extended to 14 days.
12.5.2 Membrane Curing
Approved curing compounds may be used in lieu of
22
NATIONAL BUILDING CODE OF INDIA
moist curing with the permission of the engineer-in-
charge. Such compounds shall be applied to all exposed
surfaces of the concrete as soon as possible after the
concrete has set. Impermeable membranes such as
polyethylene sheeting covering closely the concrete
surface may also be used to provide effective barrier
against evaporation.
12.6 Supervision
It is exceedingly difficult and costly to alter concrete
once placed. Hence, constant and strict supervision of
all the items of the construction is necessary during
the progress of the work, including the proportioning
and mixing of the concrete. Supervision is also of
extreme importance to check the reinforcement and
its placing before being covered.
12.6.1 Before any important operation, such as
concreting or stripping of the formwork is started,
adequate notice shall be given to the construction
supervisor.
13 CONCRETING UNDER SPECIAL
CONDITIONS
13.1 Work in Extreme Weather Conditions
During hot or cold weather, the concreting should be
done as per good practice [6-5A(30)].
13.2 Under- Water Concreting
13.2.1 When it is necessary to deposit concrete under
water, the methods, equipment, materials and
proportions of the mix to be used shall be submitted to
and approved by the engineer-in-charge before the
work is started.
13.2.2 Under-water concrete should have a slump
recommended in 6.1 . The water-cement ratio shall not
exceed 0.6 and may need to be smaller, depending on
the grade of concrete or the type of chemical attack.
For aggregates of 40 mm maximum particle size, the
cement content shall be at least 350 kg/m 3 of concrete.
13.2.3 Coffer-dams or forms shall be sufficiently tight
to ensure still water if practicable, and in any case to
reduce the flow of water to less than 3 m/min through
the space into which concrete is to be deposited. Coffer-
dams or forms in still water shall be sufficiently tight
to prevent loss of mortar through the walls. De-
watering by pumping shall not be done while concrete
is being placed or until 24 h thereafter.
13.2.4 Concrete cast under water should not fall freely
through the water. Otherwise it may be leached and
become segregated. Concrete shall be deposited
continuously until it is brought to the required height.
While depositing, the top surface shall be kept as nearly
level as possible and the formation of seams avoided.
The methods to be used for depositing concrete under
water shall be one of the following:
a) Tremie — The concrete is placed through
vertical pipes the lower end of which is always
inserted sufficiently deep into the concrete
which has been placed previously but has not
set. The concrete emerging from the pipe
pushes the material that has already been
placed to the side and upwards and thus does
not come into direct contact with water.
When concrete is to be deposited under-water
by means of tremie, the top section of the
tremie shall be a hopper large enough to hold
one entire batch of the mix or the entire
contents the transporting bucket, if any. The
tremie pipe shall be not less than 200 mm in
diameter and shall be large enough to allow a
free flow of concrete and strong enough to
withstand the external pressure of the water
in which it is suspended, even if a partial
vacuum develops inside the pipe. Preferably,
flanged steel pipe of adequate strength for the
job should be used. A separate lifting device
shall be provided for each tremie pipe with
its hopper at the upper end. Unless the lower
end of the pipe is equipped with an approved
automatic check valve, the upper end of the
pipe shall be plugged with a wadding of the
gunny sacking or other approved material
before delivering the concrete to the tremie
pipe through the hopper, so that when the
concrete is forced down from the hopper to
the pipe, it will force the plug (and along with
it any water in the pipe) down the pipe and
out of the bottom end, thus establishing a
continuous stream of concrete. It will be
necessary to raise slowly the tremie in order
to cause a uniform flow of the concrete, but
the tremie shall not be emptied so that water
enters the pipe. At,all times after the placing
of concrete is started and until all the concrete
is placed, the lower end of the tremie pipe
shall be below the tpp surface of the plastic
concrete. This will dause the concrete to build
up from below instead of flowing out over
the surface, and thus avoid formation of
laitance layers. If the charge in the tremie is
lost while depositing, the tremie shall be
raised above the concrete surface, and unless
sealed by a check valve, it shall be re-plugged
at the top end, as at the beginning, before
refilling for depositing concrete.
b) Direct placement with pumps — As in the case
of the tremie method, the vertical end piece
of the pipe line is always inserted sufficiently
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
23
deep into the previously cast concrete and
should not move to the side during pumping.
c) Drop bottom bucket — The top of the bucket
shall be covered with a canvas flap. The
bottom doors shall open freely downward and
outward when tripped. The bucket shall be
filled completely and lowered slowly to avoid
backwash. The bottom doors shall not be
opened until the bucket rests on the surface
upon which the concrete is to be deposited
and when discharged, shall be withdrawn
slowly until well above the concrete.
d) Bags — Bags of at least 0.028 m 3 capacity of
jute or other coarse cloth shall be filled about
two-thirds full of concrete, the spare end turned
under so that bag is square ended and securely
tied. They shall be placed carefully in header
and stretcher courses so that the whole mass is
interlocked. Bags used for this purpose shall
be free from deleterious materials.
e) Grouting — A series of round cages made
from 50 mm mesh of 6 mm steel and extending
over the full height to be concreted shall be
prepared and laid vertically over the area to
be concreted so that the distance between
centres of the cages and also to the faces of
the concrete shall not exceed 1 m. Stone
aggregate of not less than 50 mm nor more
than 200 mm size shall be deposited outside
the steel cages over the full area and height
to be concreted with due care to prevent
displacement of the cages.
A stable 1 :2 cement-sand grout with a water-
cement ratio of not less than 0.6 and not more
than 0.8 shall be prepared in a mechanical
mixer and sent down under pressure (about
0.2 N/mm 2 ) through 38 to 50 mm diameter
pipes terminating into steel cages, about
50 mm above the bottom of the concrete. As
the grouting proceeds, the pipe shall be raised
gradually up to a height of not more than
6 000 mm above its starting level after which
it may be withdrawn and placed into the next
cage for further grouting by the same
procedure.
After grouting the whole area for a height of
about 600 mm, the same operation shall be
repeated, if necessary, for the next layer of
600 mm and so on.
The amount of grout to be sent down shall be
sufficient to fill all the voids which may be
either ascertained or assumed as 55 percent
of the volume to be concreted.
13.2.5 To minimize the formulation of laitance, great
care shall be exercised not to disturb the concrete as
far as possible while it is being deposited.
14 SAMPLING AND STRENGTH OF DESIGNED
CONCRETE MIX
14.1 General
Samples from fresh concrete shall be taken as per
accepted standard [6-5A(16)] and cubes shall be made,
cured and tested at 28 days in accordance with accepted
standard [6-5A(9)].
14.1.1 In order to get a relatively quicker idea of the
quality of concrete, optional tests on beams for modulus
of rupture at 72 ± 2 h or at 7 days, or compressive
strength tests at 7 days may be carried out in addition
to 28 days compressive strength test. For this purpose
the values should be arrive at based on actual testing.
In all cases, the 28 days compressive strength specified
in Table 2 shall alone be the criterion for acceptance
or rejection of the concrete.
14.2 Frequency of Sampling
14.2.1 Sampling Procedure
A random sampling procedure shall be adopted to
ensure that each concrete batch shall have a reasonable
chance of being tested that is, the sampling should be
spread over the entire period of concreting and cover
all mixing units.
14.2.2 Frequency
The minimum frequency of sampling of concrete of
each grade shall be in accordance with the following:
Quantity of Concrete
Number of Samples
in the Work, m 3
1-5
1
6-15
2
16-30
3
31-50
4
51 and above
4 plus one additional sample
for each additional 50 m 3 or
part thereof
NOTE — At least one sample shall be taken from each shift.
Where concrete is produced at continuous production unit,
such as ready-mixed concrete plant, frequency of sampling
may be agreed upon mutually by suppliers and purchasers.
14.3 Test Specimen
Three test specimens shall be made for each sample
for testing at 28 days. Additional specimens may be
required for various purposes such as to detennine the
strength of concrete at 7 days or at the time of striking
the formwork, or to determine the duration of curing,
or to check the testing error. Additional specimens may
also be required for testing specimens cured by
24
NATIONAL BUILDING CODE OF INDIA
accelerated methods as described in accepted standard
[6-5A(31)]. The specimen shall be tested as described
in accepted standard [6-5 A(9)].
14.4 Test Results of Sample
The test results of the sample shall be the average of
the strength of three specimens. The individual
variation should not be more than ±15 percent of the
average. If more, the test results of the sample are
invalid.
15 ACCEPTANCE CRITERIA
15.1 Compressive Strength
The concrete shall be deemed to comply with the
strength requirements when both the following
conditions are met:
a) The mean strength determined from any
group of four non-overlapping consecutive
test results complies with the appropriate
limits in col 2 of Table 11.
b) Any individual test result complies with the
appropriate limits in col 3 of Table 11.
15.2 Flexural Strength
When both the following conditions are met, the
concrete complies with the specified flexural strength:
a) The mean strength determined from any
group of four consecutive test results exceeds
the specified characteristic strength by at least
0.3 N/mm 2 .
b) The strength determined from any test result
is not less than the specified characteristic
strength less 0.3 N/mm 2 .
15.3 Quantity of Concrete Represented by Strength
Test Results
The quantity of concrete represented by a group of
four consecutive test results shall include the batches
from which the first and last samples were taken
together with all intervening batches.
For the individual test result requirements given in col 3
of Table 11 or in 15.2 (b), only the particular batch
from which the sample was taken shall be at risk.
Where the mean rate of sampling is not specified the
maximum quantity of concrete that four consecutive
test results represent shall be limited to 60 m 3 .
15.4 If the concrete is deemed not to comply pursuant
to 15.1 or 15.2 as the case may be, the structural
adequacy of the parts affected shall be investigated
(see 16) and any consequential action as needed shall
be taken.
15.5 Concrete of each grade shall be assessed
separately.
15.6 Concrete is liable to be rejected if it is porous or
honey-combed, its placing has been interrupted without
providing a proper construction joint, the reinforcement
has been displaced beyond the tolerances specified, or
construction tolerances have not been met. However,
the hardened concrete may be accepted after carrying
out suitable remedial measures to the satisfaction of
the engineer-in-charge.
16 INSPECTION AND TESTING OF
STRUCTURES
16.1 Inspection
To ensure that the construction complies with the
design an inspection procedure should be set up
covering materials, records, workmanship and
construction.
16.1.1 Tests should be made on reinforcement and the
constituent materials of concrete in accordance with
the relevant standards. Where applicable, use should
be made of suitable quality assurance schemes.
Table 11 Characteristic Compressive Strength Compliance Requirement
(Clauses 15.1 and 15.3)
Specified Grade
(1)
Mean of the Group of 4 Non-Overlapping Consecutive
Test Results in N/mnr
(2)
Individual Test Results
in N/mm 2
(3)
M15
M 20 or above
>/ck + 0.825 x established standard deviation (rounded off to nearest 0.5 N/mm 2 ) >/ ck - 3 N/mm
or
/ck + 3 N/mm 2 , whichever is greater
>/ck + 0.825 x established standard deviation (rounded off to nearest 0.5 N/mm 2 )
>/ck - 4 N/mm
/ck + 4 N/mm 2 , whichever is greater
NOTE — In the absence of established value of standard deviation, the values given in Table 8 may be assumed, and attempt should
be made to obtain results of 30 samples as early as possible to establish the value of standard deviation.
PART 6 STRUCTURAL DESIGN — SECTION 5 CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
25
16.1.2 Care should be taken to see that:
a) design and detail are capable of being
executed to a suitable standard, with due
allowance for dimensional tolerances;
b) there are clear instructions on inspection
standards;
c) there are clear instructions on permissible
deviations;
d) elements critical to workmanship, structural
performance, durability and appearance are
identified; and
e) there is a system to verify that the quality is
satisfactory in individual parts of the structure,
especially the critical ones.
16.2 Immediately after stripping the formwork, all
concrete shall be carefully inspected and any defective
work or small defects either removed or made good
before concrete has thoroughly hardened.
16.3 Testing
In case of doubt regarding the grade of concrete used,
either due to poor workmanship or based on results of
cube strength tests, compressive strength tests of
concrete on the basis of 16.4 and/or load test (see 16.6)
may be carried out.
16.4 Core Test
16.4.1 The points from which cores are to be taken
and the number of cores required shall be at the
discretion of the engineer-in-charge and shall be
representative of the whole of concrete concerned. In
no case, however, shall fewer than three cores be tested.
16.4.2 Cores shall be prepared and tested as described
in accepted standard [6-5 A(9)].
16.4.3 Concrete in the member represented by a core
test shall be considered acceptable if the average
equivalent cube strength of the cores is equal to at least
85 percent of the cube strength of the grade of concrete
specified for the corresponding age and no individual
core has a strength less than 75 percent.
16.5 In case the core test results do not satisfy the
requirements of 16.4.3 or where such tests have not
been done, load test (16.6) may be restored to.
16.6 Load Tests for Flexural Member
16.6.1 Load tests should be carried out as soon as
possible after expiry of 28 days from the time of placing
of concrete.
16.6.2 The structure should be subjected to a load
equal to full dead load of the structure plus 1.25 times
the imposed load for a period of 24 h and then the
imposed load shall be removed.
NOTE — Dead load includes self weight of the structural
members plus weight of finishes and walls or partitions, if any,
as considered in the design.
16.6.3 The deflection due to imposed load only shall
be recorded. If within 24 h of removal of the imposed
load, the structure does not recover at least 75 percent
of the deflection under superimposed load, the test may
be repeated after a lapse of 72 h. If the recovery is less
than 80 percent, the structure shall be deemed to be
unacceptable.
16.6.3.1 If the maximum deflection in mm, shown
during 24 h under load is less than 40 P/D, where / is
the effective span in m; and D, the overall depth of the
section in mm, it is not necessary for the recovery to
be measured and the recovery provisions of 16.6.3 shall
not apply.
16.7 Members Other than Flexural Members
Members other than flexural members should be
preferably investigated by analysis.
16.8 Non-destructive Tests
Non-destructive tests are used to obtain estimation of
the properties of concrete in the structure. The methods
adopted include ultrasonic pulse velocity (see accepted
standard [6-5A(32)] ), probe penetration, pullout and
maturity. Non-destructive tests provide alternatives to
core tests for estimating the strength of concrete in a
structure, or can supplement the data obtained from a
limited number of cores. These methods are based on
measuring a concrete property that bears some
relationship to strength. The accuracy of these methods,
in part, is determined by the degree of correlation
between strength and the physical quality measured
by the non-destructive tests.
Any of these methods may be adopted, in which case
the acceptance criteria shall be agreed upon prior to
testing.
SECTION 5A (c) GENERAL DESIGN
CONSIDERATION
17 BASES FOR DESIGN
17.1 Aim of Design
The aim of design is the achievement of an acceptable
probability that structures being designed will perform
satisfactorily during their intended life. With an
appropriate degree of safety, they should sustain all
the loads and deformations of normal construction and
use and have adequate durability and adequate
resistance to the effects of misuse and fire.
17.2 Methods of Design
17.2.1 Structure and structural elements shall normally
26
NATIONAL BUILDING CODE OF INDIA
be designed by Limit State Method. Account should
be taken of accepted theories, experiment and
experience and the need to design for durability.
Calculations alone do not produce safe, serviceable and
durable structures. Suitable materials, quality control,
adequate detailing and good supervision are equally
important.
17.2.2 Where the Limit State Method can not be
conveniently adopted, Working Stress Method may be
used (see Annex B).
17.2.3 Design Based on Experimental Basis
Designs based on experimental investigations on
models or full size structure or element may be
accepted if they satisfy the primary requirements
of 17.1 and subject to experimental details and the
analysis connected therewith being approved by the
engineer-in-charge.
17.2.3.1 Where the design is based on experimental
investigation on full size structure or element, load tests
shall be carried out to ensure the following;
a) The structure shall satisfy the requirements
for deflection (see 22.2) and cracking
(see 34.3.2) when subjected to a load for 24 h
equal to the characteristic load multiplied by
1 .33 y f where 7 f shall be taken from Table 18,
for the limit state of serviceability. If within
24 h of the removal of the load, the structure
does not show a recovery of at least 75 percent
of the maximum deflection shown during the
24 h under the load, the test loading should
be repeated after a lapse of 72 h. The recovery
after the second test should be at least 75
percent of the maximum deflection shown
during the second test.
NOTE — If the maximum deflection in mm, shown
during 24 h under load is less than 40 l 2 ID where / is
the effective span in m; and D is the overall depth of
the section in mm, it is not necessary for the recovery
to be measured.
b) The structure shall have adequate strength to
sustain for 24 h, a total load equal to the
characteristic load multiplied by 1 .33 y where
y shall be taken from Table 18 for the limit
state of collapse.
17.3 Durability, Workmanship and Materials
It is assumed that the quality of concrete, steel and
other materials and of the workmanship, as verified
by inspections, is adequate for safety, serviceability
and durability.
17.4 Design Process
Design, including design for durability, construction
and use in service should be considered as a whole.
The realization of design objectives requires
compliance with clearly defined standards for
materials, production, workmanship and also
maintenance and use of structure in service.
18 LOADS AND FORCES
18.1 General
In structural design, account shall be taken of the dead,
imposed and wind loads and forces such as those
caused by earthquake, and effects due to shrinkage,
creep, temperature, etc, where applicable.
18.2 Dead Loads
Dead loads shall be calculated on the basis of unit
weights which shall be established taking into
consideration the materials specified for construction.
18.2.1 Alternatively, the dead loads may be calculated
on the basis of unit weights of materials given in good
practice [6-5A(33)]. Unless more accurate calculations
are warranted, the unit weights of plain concrete and
reinforced concrete made with sand and gravel or
crushed natural stone aggregate may be taken as
24 kN/m 3 and 25 kN/m 3 respectively.
18.3 Imposed Loads, Wind Loads and Snow Loads
Imposed loads, wind loads and snow loads shall be
assumed in accordance with good practice
[6-5A(33)].
18.4 Earthquake Forces
The earthquake forces shall be calculated in accordance
with accepted standard [6-5A(34)].
18.5 Shrinkage, Creep and Temperature Effects
If the effects of shrinkage, creep and temperature are
liable to affect materially the safety and serviceability
of the structure, these shall be taken into account in
the calculations (see 5.2.4, 5.2.5 and 5.2.6) and good
practice [6-5A(33)].
18.5.1 In ordinary buildings, such as low rise
dwellings whose lateral dimension do not exceed 45 m,
the effects due to temperature fluctuations and
shrinkage and creep can be ignored in design
calculations.
18.6 Other Forces and Effects
In addition, account shall be taken of the following
forces and effects if they are liable to affect materially
the safety and serviceability of the structure:
a) Foundation movement (see good practice
[6-5A(35)]),
b) Elastic axial shortening,
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
27
c) Soil and fluid pressures {see good practice
[6-5A(33)]),
d) Vibration,
e) Fatigue,
f) Impact {see good practice [6-5A(33)] ),
g) Erection loads {see good practice [6-5 A(33)] ),
and
h) Stress concentration effect due to point load
and the like.
18.7 Combination of Loads
The combination of loads shall be as given in good
practice [6-5A(33)].
18.8 Dead Load Counteracting Other Loads and
Forces
When dead load counteracts the effects due to other
loads and forces in structural member or joint, special
care shall be exercised by the designer to ensure
adequate safety for possible stress reversal.
18.9 Design Load
Design load is the load to be taken for use in the
appropriate method of design; it is the characteristic
load in case of working stress method and characteristic
load with appropriate partial safety factors for limit
state design.
19 STABILITY OF THE STRUCTURE
19.1 Overturning
The stability of a structure as a whole against
overturning shall be ensured so that the restoring
moment shall be not less than the sum of 1.2 times the
maximum overturning moment due to the characteristic
dead load and 1.4 times the maximum overturning
moment due to the characteristic imposed loads. In
cases where dead load provides the restoring moment,
only 0.9 times the characteristic dead load shall be
considered. Restoring moment due to imposed loads
shall be ignored.
19.1.1 The anchorages or counterweights provided for
overhanging members (during construction and
service) should be such that static equilibrium should
remain, even when overturning moment is doubled.
19.2 Sliding
The structure shall have a factor against sliding of not
less than 1 A under the most adverse combination of the
applied characteristic forces. In this case only 0.9 times
the characteristic dead load shall be taken into account.
19.3 Probable Variation in Dead Load
To ensure stability at all times, account shall be taken
of probable variations in dead load during construction,
repair or other temporary measures. Wind and seismic
loading shall be treated as imposed loading.
19.4 Moment Connection
In designing the framework of a building provisions
shall be made by adequate moment connections or by
a system of bracings to effectively transmit all the
horizontal forces to the foundations.
19.5 Lateral Sway
Under transient wind load the lateral sway at the top
should not exceed ///500, where H is the total height
of the building. For seismic loading, reference should
be made to good practice [6-5A(34)].
20 FIRE RESISTANCE
20.1 A structure or structural element required to have
fire resistance should be designed to possess an
appropriate degree of resistance to flame penetration;
heat transmission and failure. The fire resistance of a
structural element is expressed in terms of time in hours
in accordance with good practice [6-5A(36)]. Fire
resistance of concrete elements depends upon details
of member size, cover to steel reinforcement detailing
and type of aggregate (normal weight or light weight)
used in concrete. General requirements for fire
protection are given in good practice [6-5A(37)]
20.2 Minimum requirements of concrete cover and
member dimensions for normal weight aggregate
concrete members so as to have the required fire
resistance shall be in accordance with 25.4.3 and Fig. 1
respectively.
20.3 The reinforcement detailing should reflect the
changing pattern of the structural action and ensure
that both individual elements and the structure as a
whole contain adequate support, ties, bonds and
anchorages for the required fire resistance.
20.3.1 Additional measures such as application of fire
resistant finishes, provision of fire resistant false
ceilings and sacrificial steel in tensile zone, should be
adopted in case the nominal cover required exceeds
40 mm for beams and 35 mm for slabs, to give
protection against spalling.
20.4 Specialist literature may be referred to for
determining fire resistance of the structures which have
not been covered in Fig. 1 or Table 16 A.
21 ANALYSIS
21.1 General
All structures may be analyzed by the linear elastic
theory to calculate internal actions produced by design
28
NATIONAL BUILDING CODE OF INDIA
u b ^
U-l
BEAMS
SOLIDS SLAB
bw
RIB /WAFFEL SLAB
SLABS
• «. .% -•
UbJ L—D-—
FULLY EXPOSED
50 % EXPOSED
COLUMNS
> . v ... /
ONE FACE EXPOSED
Fire
Maximum
Rib
Minimum
Column Dimension (b or D) Minimum Wall Thickness
Resistance
Beam
Width
Width
of
Slabs
Thickness
of
Floors
^
_^_
Fully
50%
One Face p < 0.4%
0.4%<p<\%
P>1%
h
b
bw
D
Exposed
Exposed
Exposed
mm
mm
mm
mm
mm
mm mm
mm
mm
(1)
(2)
(3)
(4)
(5)
(6)
(7) (8)
(9)
(10)
0.5
1
1.5
2
3
4
200
200
200
200
240
280
125
125
125
125
150
175
75
95
110
125
150
170
150
200
250
300
400
450
125
160
200
200
300
350
100
120
140
160
200
240
150
150
175
100
120
140
160
200
240
100
100
100
100
150
180
NOTES
1 These minimum dimensions relate specifically to the covers given in Table 16A.
2 p is the percentage of steel reinforcement.
Fig. 1 Minimum Dimensions of Reinforced Concrete Members
for Fire Resistance
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
29
loads. In lieu of rigorous elastic analysis, a simplified
analysis as given in 21.4 for frames and as given in 21.5
for continuous beams may be adopted.
21.2 Effective Span
Unless otherwise specified, the effective span of a
member shall be as follows:
a) Simply Supported Beam or Slab — The
effective span of a member that is not built
integrally with it supports shall be taken as
clear span plus the effective depth of slab
or beam or centre to centre of supports,
whichever is less.
b) Continuous Beam or Slab — In the case of
continuous beam or slab, if the width of the
support is less than 1/12 of the clear span, the
effective span shall be as given in 21.2 (a). If
the supports are wider than 1/12 of the clear
span or 600 mm whichever is less, the
effective span shall be taken as under:
1) For end span with one end fixed and the
other continuous or for intermediate
spans, the effective span shall be the clear
span between supports;
2) For end span with one end free and the
other continuous, the effective span shall
be equal to the clear span plus half the
effective depth of the beam or slab or
the clear span plus half the width of the
discontinuous support, whichever is
less;
3) In the case of spans with roller or rocket
bearings, the effective span shall always
be the distance between the centres of
bearings.
c) Cantilever — The effective length of a
cantilever shall be taken as its length to the
face of the support plus half the effective
depth except where it forms the end of a
continuous beam where the length to the
centre of support shall be taken.
d) Frames — In the analysis of a continuous
frame, centre-to-centre distance shall be used.
21.3 Stiffness
21.3.1 Relative Stiffness
The relative stiffness of the members may be based on
the moment of inertia of the section determined on the
basis of any one of the following definitions:
a) Gross section — The cross-section of the
member ignoring reinforcement;
b) Transformed section — The concrete cross-
section plus the area of reinforcement
transformed on the basis of modular ratio
(see B-1.3); or
c) Cracked section — The area of concrete in
compression plus the area of reinforcement
transformed on the basis of modular ratio.
The assumptions made shall be consistent for all the
members of the structure throughout any analysis.
21.3,2 For deflection calculations, appropriate values
of moment of inertia as specified in Annex C should
be used.
21.4 Structural Frames
The simplifying assumptions as given in 21.4.1
to 21.4.3 may be used in the analysis of frames.
21.4.1 Arrangement of Imposed Load
a) Consideration may be limited to combinations
of:
1) Design dead load on all spans with full
design imposed load on two adjacent
spans; and
2) Design dead load on all spans with full
design imposed load on alternate spans.
b) When design imposed load does not exceed
three-fourths of the design dead load, the load
arrangement may be design dead load and
design imposed load on all the spans.
NOTE — For beams and slabs continuous over support
21.4.1 (a) may be assumed.
21.4.2 Substitute Frame
For determining the moments and shears at any floor
or roof level due to gravity loads, the beams at that
level together with columns above and below with their
far ends fixed may be considered to constitute the
frame.
21.4.2.1 Where side sway consideration becomes
critical due to unsymmetry in geometry or loading,
rigorous analysis may be required.
21.4.3 For lateral loads, simplified methods may be
used to obtain the moments and shears for structures
that are symmetrical. For uHsymmetrical or very tall
structures, more rigorous methods should be used.
21.5 Moment and Shear Coefficients for Continuous
Beams
21.5.1 Unless more exact estimates are made, for
beams of uniform cross-section which support
substantially uniformly distributed loads over three or
more spans which do not differ by more than 1 5 percent
of the longest, the bending moments and shear forces
used in design may be obtained using the coefficients
given in Table 12 and Table 13 respectively.
30
NATIONAL BUILDING CODE OF INDIA
Table 12 Bending Moment Coefficients
(CZflK.se 21.5.1)
Type of Load
(1)
Span Moments
Support Moments
Near Middle of
End Span
(2)
At Middle of
Interior Span
(3)
At Support Next to the
End Support
(4)
At Other Interior
Supports
(5)
1
+ —
12
1
+ —
10
Dead load and imposed load (fixed)
Imposed load (not fixed)
NOTE — For obtaining the bending moment, the coefficient shall be multiplied by the total design load and effective span.
16
1
+ —
11
1
10
1
9
1
12
1
9
Table 13 Shear for Coefficients
(Clauses 21.5.1 and 21.5.2)
Type of Load
(1)
At End Support
(2)
At Support Next to the End Support
Outer Side
(3)
Inner Side
(4)
At All Other Interior
Supports
(5)
Dead load and imposed load (fixed)
Imposed load (not fixed)
0.4
0.45
0.6
0.6
0.55
0.6
NOTE — For obtaining the shear force, the coefficient shall be multiplied by the total design load.
0.5
0.6
For moments at supports where two unequal spans meet
or in case where the spans are not equally loaded, the
average of the two values for the negative moment at
the support may be taken for design.
Where coefficients given in Table 12 are used for
calculation of bending moments, redistribution referred
to in 21.7 shall not be permitted.
21.5.2 Beams and Slabs Over Free End Supports
Where a member is built into a masonry wall which
develops only partial restraint, the member shall be
designed to resist a negative moment at the face of the
support of Wl/24 where W is the total design load and
/ is the effective span, or such other restraining moment
as may be shown to be applicable. For such a condition
shear coefficient given in Table 13 at the end support
may be increased by 0.05.
21.6 Critical Sections for Moment and Shear
21.6.1 For monolithic construction, the moments
computed at the face of the supports shall be used in
the design of the members at those section. For non-
monolithic construction the design of the member shall
be done keeping in view 21.2.
21.6.2 Critical Section for Shear
The shears computed at the face of the support shall
be used in the design of the member at that section
except as in 21.6.2.1.
21.6.2.1 When the reaction in the direction of the
applied shear introduces compression into the end
region of the member, sections located at a distance
less than d from the face of the support may be designed
for the same shear as that computed at distance d
(see Fig. 2).
NOTE — The above clauses are applicable for beams generally
carrying uniformly distributed load or where the principal load
is located farther than 2d from the face of the support.
21.7 Redistribution of Moments
Redistribution of moments may be done in accordance
with 36.1.1 for Limit State Method and in accordance
with B-1.2 for Working Stress Method. However,
where simplified analysis using coefficients is adopted,
redistribution of moments shall not be done.
22 BEAMS
22.0 Effective Depth
Effective depth of a beam is the distance between the
centroid of the area of tension reinforcement and the
maximum compression fibre, excluding the thickness
of finishing material not placed monolithically with
the member and the thickness of any concrete provided
to allow for wear. This will not apply to deep beams.
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
31
(a) (b)
Fig. 2 Typical Sport Conditions for Locating Factored Shear Force
22.1 T-Beams and L-Beams
22.1.1 General
A slab which is assumed to act as a compression flange
of a T-beam or L-beam shall satisfy the following:
a) The slab shall be cast integrally with the web,
or the web and the slab shall be effectively
bonded together in any other manner; and
b) If the main reinforcement of the slab is parallel
to the beam, transverse reinforcement shall
be provided as in Fig. 3; such reinforcement
shall not be less than 60 percent of the main
reinforcement at mid span of the slab.
22.1.2 Effective Width of Flange
In the absence of more accurate determination, the
effective width of flange may be taken as the following
but in no case greater than the breadth of the web plus
half the sum of the clear distances to the adj acent beams
on either side.
a) For T-beams, & f =| + ^ w +6D f
b) For L-beams, b = -$- + h + 3 D f
f 12
c) For isolated beams, the effective flange width
shall be obtained as below but in no case
greater than the actual width:
T-beams, b f =
L-beams, & f =
/n
- + K
K b J
+ 4
0.5 I
(I ^
°-+K
where
b f = Effective width of flange,
Z = Distance between points of zero moments
in the beam,
b w = Breadth of the web,
D f = Thickness of flange, and
b - Actual width of the flange.
NOTE — For continuous beams and frames, £ () may
be assumed as 0.7 times the effective span.
22.2 Control of Deflection
The deflection of a structure or part thereof shall not
adversely affect the appearance or efficiency of the
structure or finishes or partitions. The deflection shall
generally be limited to the following:
a) The final deflection due to all loads including
the effects of temperature, creep and
shrinkage and measured from the as-cast level
of the supports of floors, roofs and all other
horizontal members, should not normally
exceed span/250.
b) The deflection including the effects of
temperature, creep and shrinkage occurring
after erection of partitions and the application
of finishes should hot normally exceed span/
350 or 20 mm whichever is less.
22.2.1 The vertical deflection limits may generally be
assumed to be satisfied provided that the span to depth
ratios are not greater than the values obtained as below:
a) Basic values of span to effective depth ratios
for spans up to 10 m:
+ 4
Cantilever
7
Simply supported
20
Continuous
26
32
NATIONAL BUILDING CODE OF INDIA
BEAM
c
>//4-
br
.-?.:■. ■■:^-
* : '\*;«
■>//;4
3
P i ' l it ^' i iV!*, 1 ? * ./^ ;,
SECTION XX
Fig. 3 Transverse Reinforcement in Flange of T-Beam when
Main Reinforcement of Slab is Parallel to the Beam
b) For spans above 10 m, the values in (a) may
be multiplied by 10/span in metres, except
for cantilever in which case deflection
calculations should be made.
c) Depending on the area and the stress of steel
for tension reinforcement, the values in (a)
or (b) shall be modified by multiplying with
the modification factor obtained as per Fig. 4.
d) Depending on the area of compression
reinforcement, the value of span to depth ratio
be further modified by multiplying with the
modification factor obtained as per Fig. 5.
e) For flanged beams, the values of (a) or (b) be
modified as per Fig. 6 and the reinforcement
percentage for use in Fig. 4 and 5 should be
based on area of section equal to b { d.
NOTE — When deflections are required to be
calculated, the method given in Annex C may be used.
22.3 Slenderness Limits for Beams to Ensure
Lateral Stability
A simply supported or continuous beam shall be so
proportioned that the clear distance between the lateral
, 2
restraints does not exceed 60 b or
250 b
whichever
is less, where d is the effective depth of the beam and
b the breadth of the compression face midway between
the lateral restraints.
For a cantilever, the clear distance from the free end
of the cantilever to the lateral restraint shall not
100 b 2
exceed 25 b or whichever is less.
23 SOLID SLABS
23.1 General
The provisions of 22.2 for beams apply to slabs also.
NOTES
1 For slabs spanning in two directions, the shorter of the two
spans should be used for calculating the span to effective depth
ratios.
2 For two-way slabs of shorter spans (up to 3.5 m) with mild
steel reinforcement, the span to overall depth ratios given below
may generally be assumed to satisfy vertical deflection limits
for loading class up to 3 kN/m 2 .
Simply supported slabs 35
Continuous slabs 40
For high strength deformed bars of grade Fe 415, the values
given above should be multiplied by 0.8.
23.2 Slabs Continuous Over Supports
Slabs spanning in one direction and continuous over
supports shall be designed according to the provisions
applicable to continuous beams.
23.3 Slabs Monolithic with Supports
Bending moments in slabs (except flat slabs)
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
33
2.0
a:
o
\-
o
&
o
a 0.8
1.6
1.2
Q
O
0.4
v
\
\
\
^ ,s ^ * ion
^>^i£o
V^oT~
vjs_=240
I
I I
Note: fs IS STEEL STRESS OF SERVICE LOADS
INN/mm 2
I
0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.0
PERCENTAGE TENSION REINFORCEMENT
Area of cross - section of steel required
fs - Q.58 fy ^ rea Q f arQSS _ sec tj on f steel provided
Fig. 4 Modification Factor for Tension Reinforcement
a:
o
H
O
if
z
g
o
o
o
1.5
1.4
1.3
1.2
1.1
1.0
0.50 1.00 1.50 2.00 2.50 3.00
PERCENTAGE COMPRESSION REINFORCEMENT
Fig. 5 Modification Factor for Compression Reinforcement
f*
o
H
U-
z
g
O
a
UJ
a:
RATIO OF WEB WIDTH TO FLANGE WIDTH
Fig. 6 Reduction Factors for Ratios of Span to Effective Depth
for Flanged Beams
34
NATIONAL BUILDING CODE OF INDIA
constructed monolithically with the supports shall be
calculated by taking such slabs either as continuous
over supports and capable of free rotation, or as
members of a continuous framework with the supports,
taking into account the stiffness of such supports. If
such supports are formed due to beams which justify
fixity at the support of slabs, then the effects on the
supporting beam, such as, the bending of the web in
the transverse direction of the beam and the torsion in
the longitudinal direction of the beam, wherever
applicable, shall also be considered in the design of
the beam.
23.3.1 For the purpose of calculation of moments in
slabs in a monolithic structure, it will generally be
sufficiently accurate to assume that members connected
to the ends of such slabs are fixed in position and
direction at the ends remote from their connections
with the slabs.
23.3.2 Slabs Carrying Concentrated Load
23.3.2.1 If a solid slab supported on two opposite
edges, carries concentrated loads the maximum
bending moment caused by the concentrated loads
shall be assumed to be resisted by an effective width
of slab (measured parallel to the supporting edges)
as follows:
a) For a single concentrated load, the effective
width shall be calculated in accordance with
the following equation provided that it shall
not exceed the actual width of the slab:
K = kx
( \
i
ef
+ a
where
b ef = Effective width of slab,
k = Constant having the values given in
Table 14 depending upon the ratio of
the width of the slab (f) to the effective
span/ cf ,
x = Distance of the centroid of the
concentrated load from nearer support,
hf = Effective span, and
a = Width of the contact area of the
concentrated load from nearer support
measured parallel to the supported
edge.
And provided further that in case of a load
near the unsupported edge of a slab, the
effective width shall not exceed the above
value nor half the above value plus the
distance of the load from the unsupported
edge.
Table 14 Values of A for Simply Supported
and Continuous Slabs
(Clause 2432 A)
M«
k for Simply
k for Continuous
Supported Slabs
Slabs
(1)
(2)
(3)
0.1
0.4
0.4
0.2
0.8
0.8
0.3
1.16
1.16
0.4
1.48
1,44
0.5
1.72
1.68
0.6
1.96
1.84
0.7
2.12
1.96
0.8
2.24
2.08
0.9
2.36
2.16
1 .0 and above
2.48
2.24 .
b) For two or more concentrated loads placed in
a line in the direction of the span, the bending
moment per metre width of slab shall be
calculated separately for each load according
to its appropriate effective width of slab
calculated as in (a) above and added together
for design calculations.
c) For two or more loads not in a line in the
direction of the span, if the effective width of
slab for one load does not overlap the effective
width of slab for another load, both calculated
as in (a) above, then the slab for each load
can be designed separately. If the effective
width of slab for one load overlaps the
effective width of slab for an adjacent load,
the overlapping portion of the slab shall be
designed for the combined effect of the two
loads.
d) For cantilever solid slabs, the effective width
shall be calculated in accordance with the
following equation:
b , = l.2a A + a
ef 1
where
b ef ~ Effective width,
a, =
Distance of the concentrated load from
the face of the cantilever support, and
a = Width of contact area of the
concentrated load measured parallel to
the supporting edge.
Provided that the effective width of the cantilever
slab shall not exceed one-third the length of the
cantilever slab measured parallel to the fixed edge.
And provided further that when the concentrated
load is placed near the extreme ends of the length
of cantilever slab in the direction parallel to the
fixed edge, the effective width shall not exceed
the above value, nor shall it exceed half the above
PART 6 STRUCTURAL DESIGN — SECTION 5 CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
35
value plus the distance of the concentrated load
from the extreme end measured in the direction
parallel to the fixed edge.
23.3.2.2 For slabs other than solid slabs, the effective
width shall depend on the ratio of the transverse and
longitudinal flexural rigidities of the slab. Where this
ratio is one, that is, where the transverse and
longitudinal flexural rigidities are approximately equal,
the value of effective width as found for solid slabs
may be used. But as the ratio decreases, proportionately
smaller value shall be taken.
233.2.3 Any other recognized method of analysis for
cases of slabs covered by 23.3.2.1 and 23.3.2.2 and
for all other cases of slabs may be used with the
approval of the engineer-in-charge.
23.3.2.4 The critical section for checking shear shall
be as given in 33.2.4.1.
23.4 Slabs Spanning in Two Directions at Right
Angles
The slabs spanning in two directions at right angles
and carrying uniformly distributed load may be
designed by any acceptable theory or by using
coefficients given in Annex D. For determining
bending moments in slabs spanning in two directions
at right angles and carrying concentrated load, any
accepted method approved by the engineer-in-charge
may be adopted.
NOTE — The most commonly used elastic methods are based
on Pigeaud's or Wester guard's theory and the most commonly
used limit state of collapse method is based on Johansen's yield-
line theory.
23.4.1 Restrained Slab with Unequal Conditions at
Adjacent Panels
In some cases the support moments calculated from
Table 26 for adjacent panels may differ significantly.
The following procedure may be adopted to adjust
them:
a) Calculate the sum of moments at midspan and
supports (neglecting signs).
b) Treat the values from Table 26 as fixed end
moments.
c) According to the relative stiffness of adjacent
spans, distribute the fixed end moments
across the supports, giving new support
moments.
d) Adjust midspan moment such that, when
added to the support moments from (c)
(neglecting signs), the total should be equal
to that from (a).
If the resulting support moments are significantly
greater than the value from Table 26, the tension steel
over the supports will need to be extended further. The
procedure should be as follows:
1 ) Take the span moment as parabolic between
supports: its maximum value is as found
from (d).
2) Determine the points of contraflexure of the
new support moments [from (c)] with the span
moment [from (1)].
3) Extend half the support tension steel at each
end to at least an effective depth or 12 bar
diameters beyond the nearest point of
contraflexure.
4) Extend the full area of the support tension
steel at each end to half the distance from (3).
23.5 Loads on Supporting Beams
The loads on beams supporting solid slabs spanning
in two directions at right angles and supporting
uniformly distributed loads, may be assumed to be in
accordance with Fig. 7.
LOAD IN THIS SHADED AREA TO BE
CARRIED BY BEAM 'A' /
LOAD !N THIS SHADED
AREA TO BE CARRIED
BY BEAM BEAM B'
Fig. 7 Load Carried by Supported Beams
24 COMPRESSION MEMBERS
24.1 Definitions
24.1.1 Column or strut is a compression member, the
effective length of which exceeds three times the least
lateral dimension.
24.1.2 Short and Slender Compression Members
A compression member may be considered as short
when both the slenderness ratios — and — are less
D b
than 12:
where
/ ex = Effective length in respect of the maj or axis ,
D - Depth in respect of the major axis,
/ = Effective length in respect of the minor axis,
and
b - Width of the member.
36
NATIONAL BUILDING CODE OF INDIA
It shall otherwise be considered as a slender
compression member.
24.1.3 Unsupported Length
The unsupported length, /, of a compression member
shall be taken as the clear distance between end
restraints except that:
a) in flat slab construction, it shall be clear
distance between the floor and the lower
extremity of the capital, the drop panel or slab
whichever is the least.
b) in beam and slab construction, it shall be the
clear distance between the floor and the
underside of the shallower beam framing into
the columns in each direction at the next
higher floor level.
c) in columns restrained laterally by struts,
it shall be the clear distance between
consecutive struts in each vertical plane,
provided that to be an adequate support,
two such struts shall meet the columns at
approximately the same level and the angle
between vertical planes through the struts
shall not vary more than 30° from a right
angle. Such struts shall be of adequate
dimensions and shall have sufficient
anchorage to restrain the member against
lateral deflection.
d) in columns restrained laterally by struts or
beams, with brackets used at the junction, it
shall be the clear distance between the floor
and the lower edge of the bracket, provided
that the bracket width equals that of the beam
strut and is at least half that of the column.
24.2 Effective Length of Compression Members
In the absence of more exact analysis, the effective
length / ef of columns may be obtained as described in
Annex E.
24.3 Slenderness Limits for Columns
24.3.1 The unsupported length between end restraints
shall not exceed 60 times the least lateral dimension
of a column.
24.3.2 If, in any given plane, one end of a column is
unrestrained, its unsupported length, /, shall not
_, 100 b 2
exceed
D
where
24.4 Minimum Eccentricity
All columns shall be designed for minimum
eccentricity, equal to the unsupported length of column/
500 plus lateral dimensions/30, subject to a minimum
of 20 mm. Where bi-axial bending is considered, it is
sufficient to ensure that eccentricity exceeds the
minimum about one axis at a time.
25 REQUIREMENTS GOVERNING
REINFORCEMENT AND DETAILING
25.1 General
Reinforcing steel of same type and grade shall be used
as main reinforcement in a structural member.
However, simultaneous use of two different types or
grades of steel for main and secondary reinforcement
respectively is permissible.
25.1.1 Bars may be arranged singly, or in pairs in
contact, or in groups of three or four bars bundled in
contact. Bundled bars shall be enclosed within stirrups
or ties. Bundled bars shall be tied together to ensure
the bars remaining together. Bars larger than 32 mm
diameter shall not be bundled, except in columns.
25.1.2 The recommendations for detailing for
earthquake-resistant construction given in good
practice [6-5 A(38)] should be taken into consideration,
where applicable (see also good practice [6-5A(38)] ).
25.2 Development of Stress in Reinforcement
The calculated tension or compression in any bar at
any section shall be developed on each side of the
section by an appropriate development length or end
anchorage or by a combination thereof.
25.2.1 Development Length of Bars
The development length L & is given by
fas
h =
4t
where
b - Width of that cross-section, and
D = Depth of the cross-section measured in the
plane under consideration.
= Nominal diameter of the bar,
a s = Stress in bar at the section considered at
design load, and
x bd = Design bond stress given in 25.2.1.1.
NOTES
1 The development length includes anchorage values of
hooks in tension reinforcement.
2 For bars of sections other than circular, the development
length should be sufficient to develop the stress in the bar by
bond.
25.2.1.1 Design bond stress in limit state method for
plain bars in tension shall be as below:
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
37
Grade of M 20 M 25 M 30 M 35 M 40 and
concrete above
Design bond 1.2 1.4 1.5 1.7 1.9
stress, Tbd,
N/mm 2
For deformed bars conforming to accepted standard
[6-5A(40)] these values shall be increased by 60
percent.
For bars in compression, the values of bond stress for
bars in tension shall be increased by 25 percent.
The values of bond stress in working stress design, are
given in B-2.1.
25.2.1.2 Bars bundled in contact
The development length of each bar of bundled bars
shall be that for the individual bar, increased by 10
percent for two bars in contact, 20 percent for three
bars in contact and 33 percent for four bars in contact.
25.2.2 Anchoring Reinforcing Bars
25.2.2.1 Anchoring bars in tension
a) Deformed bars may be used without end
anchorages provided development length
requirement is satisfied. Hooks should
normally be provide for plain bars in tension.
b) Bends and hooks — Bends and hooks shall
conform to good practice [6-5A(26)]:
1 ) Bends — The anchorage value of bend
shall be taken as 4 times the diameter of
the bar for each 45° bend subject to a
maximum of 1 6 times the diameter of the
bar.
2) Hooks — The anchorage value of a
standard U-type hook shall be equal to
1 6 times the diameter of the bar.
25.2.2.2 Anchoring bars in compression
The anchorage length of straight bar in compression
shall be equal to the development length of bars in
compression as specified in 25.2.1. The projected
length of hooks, bends and straight lengths beyond
bends if provided for a bar in compression, shall only
be considered for development length.
25.2.2.3 Mechanical devices for anchorage
Any mechanical or other device capable of developing
the strength of the bar without damage to concrete may
be used as anchorage with the approval of the engineer-
in-charge.
25.2.2.4 Anchoring shear reinforcement
a) Inclined bars — The development length shall
be as for bars in tension; this length shall be
measured as under:
1) In tension zone, from the end of the
sloping or inclined portion of the bar, and
2) In the compression zone, from the mild
depth of the beam.
b) Stirrups — Notwithstanding any of the
provisions of this standard, incase of
secondary reinforcement, such as stirrups and
transverse ties, complete development lengths
and anchorage shall be deemed to have been
provided when the bar is bent through an
angle of at least 90° round a bar of at least its
own diameter and is continued beyond the end
of the curve for a length of at least eight
diameters, or when the bar is bent through an
angle of 135° and is continued beyond the
end of the curve for a length of at least six
bar diameters or when the bar is bent through
an angle of 180° and is continued beyond the
end of the curve for a length of at least four
bar diameters.
25.2.2.5 Bearing stresses at bends
The bearing stress in concrete for bends and hooks
described in good practice [6-5A(26)] need not be
checked. The bearing stress inside a bend in any other
bend shall be calculated as given below:
Bearing stress =
r$
where
F bt = Tensile force due to design loads in a bar
or group of bars,
r = Internal radius of the bend, and
= Size of the bar or, in bundle, the size of bar
of equivalent area.
For limit state method of design, this stress shall not
1.5 f A
exceed : — T77~ where f . is the characteristic cube
l + 2<j>fa Jck
strength of concrete and a, for a particular bar or group
of bars in contact shall be taken as the centre to centre
distance between bars or groups of bars perpendicular
to the plane of the bend; for a bar or group of bars
adjacent to the face of the member a shall be taken as
the cover plus size of bar (<p). For working stress
method of design, the bearing stress shall not exceed
Jck
\ + 2$la
25.2.2.6 If a change in direction of tension or
compression reinforcement induces a resultant force
acting outward tending to split the concrete, such
force should be taken up by additional links or
38
NATIONAL BUILDING CODE OF INDIA
stirrups. Bent tension bar at a re-entrant angle should
be avoided.
25.2.3 Curtailment of Tension Reinforcement in
Flexural Members
25.2.3.1 For curtailment, reinforcement shall extend
beyond the point at which it is no longer required to
resist flexure for a distance equal to the effective depth
of the member or 1 2 times the bar diameter, whichever
is greater except at simple support or end of cantilever.
In addition 25.2.3.2 to 25.2.3.5 shall also be satisfied.
NOTE — A point at which reinforcement is no longer required
to resist flexure is where the resistance moment of the section,
considering only the continuing bars, is equal to the design
moment.
25.2.3.2 Flexural reinforcement shall not be terminated
in a tension zone unless any one of the following
conditions is satisfied:
a) The shear at the cut-off point does not exceed
two-thirds that permitted, including the shear
strength of web reinforcement provided.
b) Stirrup area in excess of that required for shear
and torsion is provided along each terminated
bar over a distance from the cut-off point
equal to three-fourths the effective depth of
the member. The excess stirrup area shall be
not less than 0.4 bslf , where b is the breadth
of beam, s is the spacing and / is the
characteristic strength of reinforcement in
N/mm 2 . The resulting spacing shall not exceed
J/8 (J b where P b is the ratio of the area of bars
cut-off to the total area of bars at the section,
and d is the effective depth.
c) For 36 mm and smaller bars, the continuing
bars provide double the area required for
flexure at the cut-off point and the shear does
not exceed three-fourths that permitted.
25.2.3.3 Positive moment reinforcement
a) At least one-third the positive moment
reinforcement in simple members and one-
fourth the positive moment reinforcement in
continuous members shall extend along the
same face of the member into the support, to
a length equal to LJ3.
b) When a flexural member is part of the primary
lateral load resisting system, the positive
reinforcement required to be extended into the
support as described in (a) shall be anchored
to develop its design stress in tension at the
face of the support.
c) At simple supports and at points of inflection,
positive moment tension reinforcement shall
be limited to a diameter such that L d computed
for/ d by 25.2.1 does not exceed
V ^
where
Mj = Moment of resistance of the section
assuming all reinforcement at the section
to be stressed to/ d ;
/ d = 0.87 / y in the case of limit state design and
the permissible stress a st in the case of
working stress design;
V = Shear force at the section due to design
loads;
L Q = Sum of the anchorage beyond the centre of
the support and the equivalent anchorage
value of any hook or mechanical anchorage
at simple support; and at a point of
inflection, L Q is limited to the effective
depth of the members or 120 , whichever is
greater; and
= Diameter of bar.
The value of M /V in the above expression may be
increased by 30 percent when the ends of the
reinforcement are confined by a compressive reaction.
25.2.3.4 Negative moment reinforcement
At least one-third of the total reinforcement provided
for negative moment at the support shall extend beyond
the point of inflection for a distance not less than the
effective depth of the member of 12 or one-sixteenth
of the clear span whichever is greater.
25.2.3.5 Curtailment of bundled bars
Bars in a bundle shall terminate at different points
spaced apart by not less than 40 times the bar diameter
except for bundles stopping at a support.
25.2.4 Special Members
Adequate end anchorage shall be provided for
tension reinforcement in flexural members where
reinforcement stress is not directly proportional to
moment, such as sloped, stepped, or tapered footings;
brackets; deep beams; and members in which the
tension reinforcement is not parallel to the compression
face.
25.2.5 Reinforcement Splicing
Where splices are provided in the reinforcing bars, they
shall as far as possible be away from the sections of
maximum stress and be staggered. It is recommended
that splices in flexural members should not be at
sections where the bending moment is more than 50
percent of the moment of resistance; and not more than
half the bars shall be spliced at a section.
Where more than one-half of the bars are spliced at a
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
39
section or where splices are made at points of maximum
stress, special precautions shall be taken such as
increasing the length of lap and/or using spirals or
closely-spaced stirrups around the length of the splice.
25.2.5.1 Lap splices
a) Lap splices shall not be used for bars larger
than 36 mm; for larger diameters, bars may
be welded {see 11.4); in cases where welding
is not practicable, lapping of bars larger than
36 mm may be permitted, in which case
additional spirals should be provided around
the lapped bars.
b) Lap splices shall be considered as staggered
if the centre to centre distance of the splices
is not less than 1.3 times the lap length
calculated as described in (c).
c) Lap length including anchorage value of
hooks for bars in flexural tension shall be L ,
Q
{see 25.2.1) or 30 whichever is greater. The
straight length of the lap shall not be less than
150 or 200 mm. The following provisions
shall also apply:
Where lap occurs for a tension bar located at:
1) top of a section as cast and the minimum
cover is less than twice the diameter of
the lapped bar, the lap length shall be
increased by a factor of 1.4.
2) corner of a section and the minimum
cover to either face is less than twice the
diameter of the lapped bar or where the
clear distance between adjacent laps is
less than 75 mm or 6 times the diameter
of lapped bar, whichever is greater, the
lap length should be increased by a factor
of 1.4.
Where both conditions (1) and (2) apply,
the lap length should be increased by a
factor of 2.0.
NOTE: Splices in tension members shall be
enclosed in spirals made of bars not less than 6 mm
diameter with pitch not more than 100 mm.
d) The lap length in compression shall be equal
to the development length in compression,
calculated as described in 25.2.1, but not less
than 240.
e) When bars of two different diameters are to
be spliced, the lap length shall be calculated
on the basis of diameter of the smaller bar.
f) When splicing of welded wire fabric is to be
carried out, lap splices of wires shall be made
so that overlap measured between the extreme
cross wires shall be not less than the spacing
of cross wires plus 100 mm.
g) In case of bundled bars, lapped splices of
bundled bars shall be made by splicing one
bar at a time; such individual splices within a
bundle shall be staggered.
25.2.5.2 Strength of welds
The following values may be used where the strength
of the weld has been proved by tests to be at least as
great as that of the parent bar.
a) Splices in compression — For welded splices
and mechanical connection, 100 percent of
the design strength of joined bars.
b) Splices in tension
1 ) 80 percent of the design strength of welded
bars (100 percent if welding is strictly
supervised and if at any cross-section of
the member not more than 20 percent of
the tensile reinforcement is welded).
2) 100 percent of design strength of
mechanical connection.
25.2.5.3 End-bearing splices
End-bearing splices shall be used only for bars in
compression. The ends of the bars shall be square cut
and concentric bearing ensured by suitable devices.
25.3 Spacing of Reinforcement
25.3.1 For the purpose of this clause, the diameter of
a round bar shall be its nominal diameter, and in the
case of bars which are not round or in the case of
deformed bars or crimped bars, the diameter shall be
taken as the diameter of a circle giving an equivalent
effective area. Where spacing limitations and ininimum
concrete cover {see 25.4) are based on bar diameter, a
group of bars bundled in contact shall be treated as a
single bar of diameter derived from the total equivalent
area.
25.3.2 Minimum Distance Between Individual Bars
The following shall apply for spacing of bars:
a) The horizontal distance between two parallel
main reinforcing bars shall usually be not less
than the greatest*^ the following:
1) The diameter of the bar if the diameters
are equal,
2) The diameter of the larger bar if the
diameters are unequal, and
3) 5 mm more than the nominal maximum
size of coarse aggregate.
NOTE — This does not preclude the use of larger
size of aggregates beyond the congested
reinforcement in the same member; the size of
aggregates may be reduced around congested
reinforcement to comply with this provision.
40
NATIONAL BUILDING CODE OF INDIA
b) Greater horizontal distance than the minimum
specified in (a) should be provided wherever
possible. However, when needle vibrators are
used the horizontal distance between bars of
a group may be reduced to two-thirds
the nominal maximum size of the coarse
aggregate, provided that sufficient space is left
between groups of bars to enable the vibrator
to be immersed.
c) Where there are two or more rows of bars,
the bars shall be vertically in line and the
minimum vertical distance between the bars
shall be 15 mm, two-thirds the nominal
maximum size of aggregate or the maximum
size of bars, whichever is greater.
25.3.3 Maximum Distance Between Bars in Tension
Unless the calculation of crack widths shows that a
greater spacing is acceptable, the following rules shall
be applied to flexural members in normal internal or
external conditions of exposure.
a) Beams — The horizontal distance between
parallel reinforcement bars, or groups, near
the tension face of a beam shall not be greater
than the value given in Table 15 depending
on the amount of re-distribution carried out
in analysis and the characteristic strength of
the reinforcement.
Table 15 Clear Distance Between Bars
(Clause 25.3.3)
fl
Percentage Re-distribution to or 1
Section Considered
from
-30
-15
+15
+ 30
Clear Distance Between Bars
N/mm 2
mm
mm
mm
mm
mm
(1)
(2)
(3)
(4)
(5)
(6)
250
415
500
215
125
105
260
155
130
300
180
150
300
210
175
300
235
195
NOTE — The spacings given in table are not applicable to
members subjected to particularly aggressive environments
unless in the calculation of the moment of resistance f y has
been limited to 300 N/mm 2 in limit state design and o st
limited to 165 N/mm 2 in working stress design.
b) Slabs
1 ) The horizontal distance between parallel
main reinforcement bars shall not be
more than three times the effective depth
of solid slab or 300 mm whichever is
smaller.
2) The horizontal distance between parallel
reinforcement bars provided against
shrinkage and temperature shall not be
more than five times the effective depth
of a solid slab or 450 mm whichever is
smaller.
25.4 Nominal Cover to Reinforcement
25.4.1 Nominal Cover
Nominal cover is the design depth of concrete cover
to all steel reinforcements, including links. It is the
dimension used in design and indicated in the drawings.
It shall be not less than the diameter of the bar.
25.4.2 Nominal Cover to Meet Durability Requirement
Minimum values for the nominal cover of normal-
weight aggregate concrete which should be provided
to all reinforcement, including links depending on the
condition of exposure described in 7.2.2 shall be as
given in Table 16.
25.4.2.1 However for a longitudinal reinforcing bar
in a column nominal cover shall in any case not be
less than 40 mm, or less than the diameter of such bar.
In the case of columns of minimum dimension of
200 mm or under, whose reinforcing bars do not exceed
12 mm, a nominal cover of 25 mm may be used.
25.4.2.2 For footings minimum cover shall be 50 mm.
25.4.3 Nominal Cover to Meet Specified Period of Fire
Resistance
Minimum values of nominal cover of normal- weight
aggregate concrete to be provided to all reinforcement
including links to meet specified period of fire
resistance shall be given in Table 16 A.
Table 16 Nominal Cover to Meet Durability
Requirements
(Clause 25.4.2)
Exposure
Nominal Concrete Cover in mm
not Less Than
(1)
(2)
Mild
Moderate
Severe
Very Severe
Extreme
20
30
45
50
75
NOTES
1 For main reinforcement up to 1 2 mm diameter bar for mild
exposure the nominal cover may be reduced by 5 mm.
2 Unless specified otherwise, actual concrete cover should not
deviate from the required nominal cover by _Qinm.
3 For exposure condition 'severe* and 'very severe', reduction
of 5 mm may be made, where concrete grade is M 35 and
above.
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
41
Tabie 16A Nominai Cover to Meet Specified Feriod of t ire Resistance
(Clauses 20.4 and 25 .4.3 and Fig. 1)
Fire
Resistance
Beams
Nominal Cover
Simply
supported
Continuous
Slabs
Ribs
Columns
Simply
supported
Continuous
Simply
supported
Continuous
h
mm
mm
mm
mm
mm
mm
mm
(0
(2)
(3)
(4)
(5)
(6)
(7)
(8)
0.5
20
20
20
20
20
20
40
1
20
20
20
20
20
20
40
1.5
20
20
25
20
35
20
40
2
40
30
35
25
45
35
40
3
60
40
45
35
55
45
40
4
70
50
55
45
65
55
40
NOTES
1 The nominal covers given relate specifically to the minimum member dimensions given in Fig. 1 .
2 Cases that lie below the bold line require attention to the additional measures necessary to reduce the risks of spalling (see 20.3.1).
25.5 Requirements of Reinforcement for
Structural Members
25.5.1 Beams
25.5.1.1 Tension reinforcement
a) Minimum reinforcement — The minimum
area of tension reinforcement shall be not less
than that given by the following:
A _ 0.85
bd~
where
b)
/v
A s = Minimum area of tension reinforcement,
b = Breadth of beam of the breadth of the
web of T-beam,
d - Effective depth, and
f y = Characteristic strength of reinforcement
in N/mm 2 .
Maximum reinforcement — The maximum
area of tension reinforcement shall not exceed
0.04 bD.
25.5.1.2 Compression reinforcement
The maximum area of compression reinforcement shall
not exceed 0,04 bD, Compression reinforcement in
beams shall be enclosed by stirrups for effective lateral
restraint. The arrangement of stirrups shall be as
specified in 25.5.3.2.
25.5.1.3 Side face reinforcement
Where the depth of the web in a beam exceeds 750 mm,
side face reinforcement shall be provided along the
two faces. The total area of such reinforcement shall
be not less than 0.1 percent of the web area and
shall be distributed equally on two faces at a spacing
not exceeding 300 mm or web thickness whichever is
less.
25.5.1.4 Transverse reinforcement in beams for shear
and torsion
The transverse reinforcement in beams shall be taken
around the outer-most tension and compression bars.
In T-beams and I-beams, such reinforcement shall pass
around longitudinal bars located close to the outer face
of the flange.
25.5.1.5 Maximum spacing of shear reinforcement
The maximum spacing of shear reinforcement
measured along the axis of the member shall not exceed
0.75 d for vertical stirrups and d for inclined stirrups
at 45°, where d is the effective depth of the section
under consideration. In no case shall the spacing exceed
300 mm.
25.5.1.6 Minimum shear reinforcement
Minimum shear reinforcement in the form of stirrups
shall be provided such that:
Av ^ Q-4
where
A, =
s =
fo v 0.87/ y
Total cross -sectional area of stirrups legs
effective in shear,
Stirrup spacing along the length of the
member,
42
NATIONAL BUILDING CODE OF INDIA
b = Breadth of the beam or breadth of the web
of flanged beam, and
/ = Characteristic strength of the stirrup
reinforcement in N/mm 2 which shall not
be taken greater than 415 N/mm 2 .
Where the maximum shear stress calculated is less than
half the permissible value and in members of minor
structural importance such as lintels, this provision
need not be complied with.
25.5.1.7 Distribution of torsion reinforcement
When a member is designed for torsion (see 40
or B-6) torsion reinforcement shall be provided as
below:
a) The transverse reinforcement for torsion
shall be rectangular closed stirrups placed
perpendicular to the axis of the member. The
spacing of the stirrups shall not exceed the
least of x } ,
*+?!
and 300 mm, where jc and
y y are respectively the short and long
dimensions of the stirrup.
b) Longitudinal reinforcement shall be placed as
close as is practicable to the corners of the
cross-section and in all cases, there shall be
at least one longitudinal bar in each corner of
the ties. When the cross-sectional dimension
of the member exceeds 450 mm, additional
longitudinal bars shall be provided to satisfy
the requirements of minimum reinforcement
and spacing given in 25.5.1.3.
25.5.1.8 Reinforcement in flanges of T-beams and
L-beams shall satisfy the requirements in 22.1.1(b).
Where flanges are in tension, a part of the main tension
reinforcement shall be distributed over the effective
flange width or a width equal to one-tenth of the span,
whichever is smaller. If the effective flange width
exceeds one-tenth of the span, nominal longitudinal
reinforcement shall be provided in the outer portions
of the flange.
25.5.2 Slabs
The rules given in 25.5.2.1 and 25.5.2.2 shall apply to
slabs in addition to those given in the appropriate
clauses.
25.5.2.1 Minimum reinforcement
The mild steel reinforcement in either direction in slabs
shall not be less than 0.15 percent of the total cross-
sectional area. However, this value can be reduced to
0.12 percent when high strength deformed bars or
welded wire fabric are used.
25.5.2.2 Maximum diameter
The diameter of reinforcing bars shall not exceed one-
eight of the total thickness of the slab.
25.5.3 Columns
25.5.3.1 Longitudinal reinforcement
a) The cross-sectional area of longitudinal
reinforcement, shall be not less than 0.8
percent nor more than 6 percent of the gross
cross-sectional area of the column.
NOTE — The use of 6 percent reinforcement
may involve practical difficulties in placing and
compacting of concrete; hence lower percentage is
recommended. Where bars from the columns below
have to be lapped with those in the column under
consideration, the percentage of steel shall usually not
exceed 4 percent.
b) In any column that has a larger cross-sectional
area than that required to support the load,
the minimum percentage of steel shall be
based upon the area of concrete required to
resist the direct stress and not upon the actual
area.
c) The minimum number of longitudinal bars
provided in a column shall be four in
rectangular columns and six in circular
columns.
d) The bars shall not be less than 12 mm in
diameter.
e) A reinforced concrete column having helical
reinforcement shall have at least six bars of
longitudinal reinforcement within the helical
reinforcement.
f) In a helically reinforced column, the longitudinal
bars shall be in contact with the helical
reinforcement and equidistant around its inner
circumference.
g) Spacing of longitudinal bars measured along
the periphery of the column shall not exceed
300 mm.
h) In case of pedestals in which the longitudinal
reinforcement is not taken in account in
strength calculations, nominal longitudinal
reinforcement not less than 0.15 percent of
the cross-sectional area shall be provided.
NOTE — Pedestal is a compression member, the
effective length of which does not exceed three times
the least lateral dimension.
25.5.3.2 Transverse reinforcement
a) General — A reinforced concrete compression
member shall have transverse or helical
reinforcement so disposed that every
longitudinal bar nearest to the compression
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
43
b)
face has effective lateral support against
buckling subject to provisions in (b). The
effective lateral support is given by
transverse reinforcement either in the form
of circular rings capable of taking up
circumferential tension or by polygonal links
(lateral ties) with internal angles not
exceeding 135°. The ends of the transverse
reinforcement shall be properly anchored
[see 25.2.2 A (b)].
Arrangement of transverse reinforcement
1) If the longitudinal bars are not spaced
more than 75 mm on either side, transverse
reinforcement need only to go round
corner and alternate bars for the purpose
of providing effective lateral supports
(see Fig. 8).
< 75mm — »■
2)
3)
<75mm
Fig. 8
If the longitudinal bars spaced at a
distance of not exceeding 48 times the
diameter of the tie are effectively tied in
two directions, additional longitudinal
bars in between these bars need to be
tied in one direction by open ties (see
Fig. 9).
■-^~0tr
h— < 48 tr -*^
Fig. 9
Where the longitudinal reinforcing bars
in a compression member are placed in
more than one row, effective lateral
support to the longitudinal bars in the
inner rows may be assumed to have been
provided if:
ii)
transverse reinforcement is provided
for the outer-most row in accordance
with 25.5.3.2, and
no bar of the inner row is closer to
the nearest compression face than
three times the diameter of the
largest bar in the inner row (see
Fig. 10).
>30
DIAMETER
>30
4)
Fig. 10
Where the longitudinal bars in a
compression member are grouped (not in
contact) and each group adequately
tied with transverse reinforcement in
accordance with 25.5.3.2, the transverse
reinforcement for the compression
member as a whole may be provided on
the assumption that each group is a
single longitudinal bar for purpose of
determining the pitch and diameter of the
transverse reinforcement in accordance
with 25.5.3.2. The diameter of such
transverse reinforcement need not,
however, exceed 20 mm (see Fig. 11).
r TRANSVERSE
\ REINFORCEMENT
INDIVIDUAL
GROUPS
Fig. 11
44
NATIONAL BUILDING CODE OF INDIA
c) Pitch and diameter of lateral ties
1) Pitch — The pitch of transverse
reinforcement shall be not more than the
least of the following distances:
i) The least lateral dimension of the
compression members;
ii) Sixteen times the smallest diameter
of the longitudinal reinforcement bar
to be tied; and
iii) 300 mm.
2) Diameter — The diameter of the
polygonal links or lateral ties shall be not
less than one-fourth of the diameter of
the largest longitudinal bar, and in no case
less than 6 mm.
d) Helical reinforcement
1) Pitch — Helical reinforcement shall be
of regular formation with the turns of the
helix spaced evenly and its ends shall be
anchored properly by providing one and
a half extra turns of the spiral bar. Where
an increased load on the column on the
strength of the helical reinforcement is
allowed for, the pitch of helical turns shall
be not more than 75 mm, nor more than
one- sixth of the core diameter of the
column, nor less than 25 mm, nor less
than three times the diameter of the steel
bar forming the helix. In other cases,
the requirements of 25.5.3.2 shall be
complied with.
2) The diameter of the helical reinforcement
shall be in accordance with 25.5.3.2 (c)
(2).
25.5.3.3 In columns where longitudinal bars are offset
at a splice, the slope of the inclined portion of the bar
with the axis of the column shall not exceed 1 in 6,
and the portions of the bar above and below the offset
shall be parallel to the axis of the column. Adequate
horizontal support at the offset bends shall be treated
as a matter of design, and shall be provided by metal
ties, spirals, or parts of the floor construction. Metal
ties or spirals so designed shall be placed near (not
more than eight-bar diameters from) the point of bend.
The horizontal thrust to be resisted shall be assumed
as one and half times the horizontal components of
the nominal stress in the inclined portion of the bar.
Offset bars shall be bent before they are placed in the
forms. Where column faces are offset 75 mm or more,
splices of vertical bars adjacent to the offset face shall
be made by separate dowels overlapped as specified
in 25.2.5.1.
26 EXPANSION JOINTS
26.1 Structures in which marked changes in plan
dimensions take place abruptly shall be provided with
expansion on joints at the section where such changes
occur. Expansion joints shall be so provided that the
necessary movement occurs with a minimum resistance
at the joint. The structures adjacent to the joint should
preferably be supported on separate columns or
walls but not necessarily on separate foundations.
Reinforcement shall not extend across an expansion
joint and the break between the sections shall be
complete.
26.2 The details as to the length of a structure where
expansion joints have to be provided can be determined
after taking into consideration various factors, such as
temperature, exposure to weather, the time and season
of the laying of the concrete, etc. Normally structures
exceeding 45 m in length are designed with one or
more expansion joints. However in view of the large
number of factors involved in deciding the location,
spacing and nature of expansion joints, the provision
of expansion joint in reinforced cement concrete
structures should be left to the discretion of the
designer. Good practice [6-5A(41)J gives the design
considerations, which need to be examined and
provided for.
SECTION 5A (d)
SPECIAL DESIGN REQUIREMENTS
FOR STRUCTURAL MEMBERS
AND SYSTEMS
27 CONCRETE CORBELS
27.1 General
A corbel is a short cantilever projection which supports
a load bearing member and where:
a) the distance a between the line of the reaction
/ V
to the supported load and the root of the corbel
is less than d (the effective depth of the root
of the corbel); and
b) the depth at the opter edge of the contact area
of the supported load is not less than one-half
of the depth at the root of the corbel.
The depth of the corbel at the face of the support is
determined in accordance with 39.5.1.
27.2 Design
27.2.1 Simplifying Assumptions
The concrete and reinforcement may be assumed to
act as elements of a simple strut-and-tie system, with
the following guidelines:
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
45
a) The magnitude of the resistance provided to
horizontal force should be not less than one-
half of the design vertical load on the corbel
(see also 21.2 A).
b) Compatibility of strains between the strut-
and-tie at the corbel root should be ensured.
It should be noted that the horizontal link requirement
described in 27.2.3 will ensure satisfactory serviceability
performance.
27.2.2 Reinforcement Anchorage
At the front face of the corbel, the reinforcement should
be anchored either by:
a) welding to a transverse bar of equal strength
— In this case the bearing area of the load
should stop short of the face of the support
by a distance equal to the cover of the tie
reinforcement, or
b) bending back the bars to form a loop —
In this case the bearing area of the load
should not project beyond the straight
portion of the bars forming the main tension
reinforcement.
27.2.3 Shear Reinforcement
Shear reinforcement should be provided in the form
of horizontal links distributed in the upper two-third
of the effective depth of root of the corbel; this
reinforcement should be not less than one-half of the
area of the main tension reinforcement and should be
adequately anchored.
27.2.4 Resistance to Applied Horizontal Force
Additional reinforcement connected to the supported
member should be provided to transmit this force in
its entirety.
28 DEEP BEAMS
28.1 General
a) A beam shall be deemed to be a deep beam
when the ratio of effective span to overall
/
depth, — is less than:
1) 2.0 for a simply supported beam; and
2) 2.5 for a continuous beam.
b) A deep beam complying with the requirements
of 28.2 and 28.3 shall be deemed to satisfy
the provisions for shear.
28.2 Lever Arm
The lever arm z for a deep beam shall be determined
as below:
a) For simply supported beams:
z = 0.2 (/ + ID) when 1 < — < 2
or
z = 0.6
b) For continuous beams
when ~<1
z = 0.2 (/+ 1 .5D) when 1 < — < 2.5
or
z = 0.5/
when — <1
where / is the effective span taken as centre to
centre distance between supports or 1 . 1 5 times the
clear span, whichever is smaller, and D is the
overall depth.
28.3 Reinforcement
28.3.1 Positive Reinforcement
The tensile reinforcement required to resist positive
bending moment in any span of a deep beam shall:
a) extend without curtailment between
supports;
b) be embedded beyond the face of each support,
so that at the face of the support it shall have
a development length not less than 0.8 L d ;
where L d is the development length (see 25.2.1),
for the design stress in the reinforcement;
and
c) be placed within a zone of depth equal to
0.25 D - 0.05 / adjacent to the tension face of
the beam where D is the overall depth and / is
the effective span.
28.3.2 Negative Reinforcement
a) Termination of reinforcement — For tensile
reinforcement required to resist negative
bending moment over a support of a deep
beam:
1) It shall be permissible to terminate not
more than half of the reinforcement at a
distance of 0.5 D from the face of the
support where D is as defined in 29.2;
and
2) The remainder shall extend over the full
span.
b) Distribution — When ratio of clear span to
overall depth is in the range 1 .0 to 2.5, tensile
reinforcement over a support of a deep beam
shall be placed in two zones comprising:
46
NATIONAL BUILDING CODE OF INDIA
1)
a zone of depth 0.2 D, adjacent to
the tension face, which shall contain
a proportion of the tension steel given
by
0.5
D
-0.5
where
/ = Clear span, and
D = Overall depth.
2) A zone measuring 0.3 D on either side
of the mid-depth of the beam, which shall
contain the remainder of the tension steel,
evenly distributed.
For span to depth ratios less than unity,
the steel shall be evenly distributed over
a depth of 0.8 D measured from the
tension face.
28.3.3 Vertical Reinforcement
If forces are applied to a deep beam in such a way that
hanging action is required, bars or suspension stirrups
shall be provided to carry all the forces concerned.
28.3.4 Side Face Reinforcement
Side face reinforcement shall comply with requirements
of minimum reinforcement of wall (see 31.4).
29 RIBBED, HOLLOW BLOCK OR VOIDED
SLAB
29.1 General
This covers the slabs constructed in one of the ways
described below:
a) As a series of concrete ribs with topping cast
on forms which may be removed after the
concrete has set;
b) As a series of concrete ribs between precast
blocks which remain part of the completed
structure; the top of the ribs may be connected
by a topping of concrete of the same strength
as that used in the ribs; and
c) With a continuous top and bottom face but
containing voids of rectangular, oval or other
shape.
29.2 Analysis of Structure
The moments and forces due to design loads on
continuous slabs may be obtained by the methods given
in Section 5A (c) for solid slabs. Alternatively, the slabs
may be designed as a series of simply supported spans
provided they are not exposed to weather or corrosive
conditions; wide cracks may develop at the supports
and the engineer shall satisfy himself that these will
not impair finishes or lead to corrosion of the
reinforcement.
29.3 Shear
Where hollow blocks are used, for the purpose of
calculating shear stress, the rib width may be increased
to take account of the wall thickness of the block on
one side of the rib; with narrow precast units, the width
of the jointing mortar or concrete may be included.
29.4 Deflection
The recommendations for deflection in respect of
solid slabs may be applied to ribbed, hollow block or
voided construction. The span to effective depth ratios
given in 22.2 for a flanged beam are applicable but
when calculating the final reduction factor for web
width, the rib width for hollow block slabs may be
assumed to include the walls of the blocks on both
sides of the rib. For voided slabs and slabs constructed
of box or I-section units, an effective rib width shall
be calculated assuming all material below the upper
flange of the unit to be concentrated in a rectangular
rib having the same cross-sectional area and depth.
29.5 Size and Position of Ribs
In-situ ribs shall be not less than 65 mm wide. They
shall be spaced at centres not greater than 1.5 m apart
and their depth, excluding any topping, shall be not
more than four times their width. Generally ribs shall
be formed along each edge parallel to the span of one
way slabs. When the edge is built into a wall or rests
on a beam, a rib at least as wide as the bearing shall be
formed along the edge.
29.6 Hollow Blocks and Formers
Blocks and formers may be of any suitable material.
Hollow clay tiles for the filler type shall conform
to accepted standard [6-5A(42)]. When required
to contribute to the structural strength of a slab they
shall:
a) be made of concrete or burnt clay; and
b) have a crushing strength of at least 14 N/mm 2
measured on the net section when axially
loaded in the direction of compressive stress
in the slab.
29.7 Arrangement of Reinforcement
The recommendations given in 25.3 regarding
maximum distance between bars apply to areas of solid
concrete in this form of construction. The curtailment,
anchorage and cover to reinforcement shall be as
described below:
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
47
a) At least 50 percent of the total main
reinforcement shall be carried through at the
bottom on to the bearing and anchored in
accordance with 25.2.3.3.
b) Where a slab, which is continuous over
supports, has been designed as simply
supported, reinforcement shall be provided
over the support to control cracking. This
reinforcement shall have a cross-sectional
area of not less than one-quarter that required
in the middle of the adjoining spans and shall
extend at least one-tenth of the clear span into
adjoining spans.
c) In slabs with permanent blocks, the side cover
to the reinforcement shall not be less than
10 mm. In all other cases, cover shall be
provided according to 25.4.
29.8 Precasts Joists and Hollow Filler Blocks
The construction with precast joists and hollow
concrete filler blocks shall conform to good
practice [6-5A(43)] and precast joist and hollow clay
filler blocks shall conform to good practice
[6-5A(44)].
30 FLAT SLABS
30.1 General
The term flat slab means a reinforced concrete slab
with or without drops, supported generally without
beams, by columns with or without flared column
heads (see Fig. 12). A flat slab may be solid slab or
may have recesses formed on the soffit so that the soffit
comprises a series of ribs in two directions. The
recesses may be formed by removable or permanent
filler blocks.
30.1.1 For the purpose of this clause, the following
definitions shall apply:
a) Column strip — Column strip means a design
strip having a width of 0.25 Z 2 , but not greater
than 0.25 l x on each side of the column centre-
line, where l x is the span in the direction
moments are being determined, measured
centre-to-centre of supports and Z 2 is the span
transverse to Z , measured centre-to-centre of
supports.
b) Middle strip — Middle strip means a design
strip bounded on each of its opposite sides by
the column strip.
c) Panel — Panel means that part of a slab
bounded on each of its four sides by the
centre-line of a column or centre-lines of
adjacent spans.
30.2 Proportioning
30.2.1 Thickness of Flat Slab
The thickness of the flat slab shall be generally
controlled by considerations of span to effective depth
ratios given in 22.2.
For slabs with drops conforming to 30.2.2, span to
effective depth ratios given in 22.2 shall be applied
directly; otherwise the span to effective depth ratios
obtained in accordance with provisions in 22.2 shall
be multiplied by 0.9. For this purpose, the longer span
shall be considered. The minimum thickness of slab
shall be 125 mm.
30.2.2 Drop
The drops when provided shall be rectangular in plan,
and have a length in each direction not less than one-
third of the panel length in that direction. For exterior
panels, the width of drops at right angles to the non-
continuous edge and measured from the centre-line of
the columns shall be equal to one-half the width of
drop for interior panels.
30.2.3 Column Heads
Where column heads are provided, that portion of a
column head which lies within the largest right circular
cone or pyramid that has a vertex angle of 90° and can
be included entirely within the outlines of the column
and the column head, shall be considered for design
purposes (see Fig. 12).
30.3 Determination of Bending Moment
30.3.1 Methods of Analysis and Design
It shall be permissible to design the slab system by
one of the following methods:
a) The direct design method as specified in 30.4,
and
b) The equivalent frame method as specified
in 30.5.
In each case the applicable limitations given in 30.4
and 30.5 shall be met.
30.3.2 Bending Moments in Panels with Marginal
Beams or Walls
Where the slab is supported by a marginal beam with
a depth greater than 1 .5 times the thickness of the slab,
or by a wall, then:
a) the total load to be carried by the beam or
wall shall comprise those loads directly on
the wall or beam plus a uniformly distributed
load equal to one-quarter of the total load on
the slab, and
48
NATIONAL BUILDING CODE OF INDIA
CRITICAL SECTION
FOR SHEAR
7
De
COLUMN
d/2i—
12 A SLAB WITHOUT DROP & COLUMN
WITHOUT COLUMN HEAD
CRITICAL SECTION FOR
SHEAR ADJACENT
CRITICAL SECTION FOR
SHEAR IMMEDIATELY
ADJACENT TO COLUMN
12 B SLAB WITH DROP & COLUMN WITH
COLUMN HEAD
CRITICAL SECTION
FOR SHEAR
ANY CONCRETE1N THIS AREA
TO BE NEGLECTED IN THE
CALCULATIONS
12 C SLAB WITHOUT DROP & COLUMN WITH
COLUMN HEAD
NOTE — D t is the diameter of column or column head to be considered for design and d is effective depth of
slab or drop as appropriate.
Fig. 12 Critical Sections for Shear in Flat Slabs
PART 6 STRUCTURAL DESIGN — SECTION 5 CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
49
b) the bending moments on the half-column strip
adjacent to the beam or wall shall be one-
quarter of the bending moments for the first
interior column strip.
30.3.3 Transfer of Bending Moments to Columns
When unbalanced gravity load, wind, earthquake, or
other lateral loads cause transfer of bending moment
between slab and column, the flexural stresses shall
be investigated using a fraction, a of the moment given
by:
a =
1
l+~7 a i /fl 2
where
a, = Overall dimension of the critical section for
shear in the direction in which moment acts,
and
a 2 - Overall dimension of the critical section for
shear transverse to the direction in which
moment acts.
A slab width between lines that are one and one-half
slab or drop panel thickness; 1.5 D, on each side of the
column or capital may be considered effective, D being
the size of the column.
Concentration of reinforcement over column head by
closer spacing or additional reinforcement may be used
to resist the moment on this section.
30.4 Direct Design Method
30.4.1 Limitations
Slab system designed by the direct design method shall
fulfil the following conditions:
a) There shall be minimum of three continuous
spans in each direction,
b) The panels shall be rectangular, and the ratio
of the longer span to the shorter span within
a panel shall not be greater than 2.0,
c) It shall be permissible to offset columns to a
maximum of 10 percent of the span in the
direction of the offset notwithstanding the
provision in (b),
d) The successive span lengths in each direction
shall not differ by more than one-third of the
longer span. The end spans may be shorter
but not longer than the interior spans, and
e) The design live load shall not exceed three
times the design dead load.
30.4.2 Total Design Moment for a Span
30.4.2.1 In the direct design method, the total design
movement for a span shall be determined for a strip
bounded laterally by the centre-line of the panel on
each side of the centre-line of the supports.
30.4.2.2 The absolute sum of the positive and average
negative bending movements in each direction shall
be taken as:
M =
8
where
M = Total movement;
o '
W = Design load on an area l 2 / n ;
l n = Clear span extending from face-to-face of
columns, capitals, brackets or walls, but not
less than 0.65 /,;
l { = Length of span in the direction of M \ and
l 2 = Length of span transverse to l { .
30.4.2.3 Circular supports shall be treated as square
supports having the same area.
30.4.2.4 When the transverse span of the panels on
either side of the centre-line of supports varies l 2 shall
be taken as the average of the transverse spans.
30.4.2.5 When the span adjacent and parallel to an
edge is being considered, the distance from the edge
to the centre-line of the panel shall be substituted for
l 2 in 30.4.2.2.
30.4.3 Negative and Positive Design Moments
30.4.3.1 The negative design moment shall be located
at the face of rectangular supports, circular supports
being treated as square supports having the same area.
30.4.3.2 In an interior span, the total design moment
M Q shall be distributed in the following proportions:
Negative design moment 0.65
Positive design moment 0.35
30.4.3.3 In an end span, the total design moment M o
shall be distributed in the following proportions:
Interior negative design moment:
0.75*- - 10
1 +
1
a.
Positive design moment:
0.63-
0.28
1 + -
a.
Exterior negative design moment:
0.65
1 +
1
50
NATIONAL BUILDING CODE OF INDIA
cc c is the ratio of flexural stiffness of the exterior
columns to the flexural stiffness of the slab at a joint
taken in the direction moments are being determined
and is given by
a, =-
IK
where
K
K
Sum of the flexural stiffness of the columns
meeting at the joint; and
Flexural stiffness of the slab, expressed as
moment per unit rotation.
30.4.3.4 It shall be permissible to modify these design
moments by up to 10 percent, so long as the total design
moment, M q for the panel in the direction considered
is not less than that required by 30,4,2*2,
30.4.3.5 The negative moment section shall be
designed to resist the larger of the two interior negative
design moments determined for the spans framing into
a common support unless an analysis is made to
distribute the unbalanced moment in accordance with
the stiffness of the adjoining parts.
30.4.4 Distribution of Bending Moments Across the
Panel Width
Bending moments at critical cross-section shall be
distributed to the column strips and middle strips as
specified in 30.5.5 as applicable.
30.4.5 Moments in Columns
30.4.5.1 Columns built integrally with the slab system
shall be designed to resist moments arising from loads
on the slab system.
30.4.5.2 At an interior support, the supporting
members above and below the slab shall be designed
to resist the moment M given by the following equation,
in direct proportion to their stiffnesses unless a general
analysis is made:
M = 0.08
(w d +Q.5w,)/ 2 (-^
1
1 + -
«,
where
vv d , w { - Design dead and live loads respectively,
per unit area;
/ 2 = Length of span transverse to the direction
ofM;
/ n = Length of the clear span in the direction
of M, measured face to face of supports;
a c = v v where K and K are as defined
in 30,4,3.3; and
w' d , 1' 2 and l' n , refer to the shorter span.
30.4.6 Effects of Pattern Loading
In the direct design method, when the ratio of live load
to dead load exceeds 0.5;
a)
b)
the sum of the flexural stiffness of the columns
above and below the slab, X K c , shall be such
that a c is not less than the appropriate
minimum value a cmin specified in Table 17,
or
if the sum of the flexural stiffnesses of the
columns, X/T c ,does not satisfy (a), the
positive design moments for the panel shall
be multiplied by the coefficient /? s given by
the following equation:
A=i+
4 + _A
1-
<X
a r
a c is the ratio of flexural stiffness of the
columns above and below the slab to the
flexural stiffness of the slabs at a joint taken in
the direction moments are being determined
and is given by:
or, =:
where K and K are flexural stiffnesses of
c s
column and slab respectively.
Table 17 Minimum Permissible Values of oc c
(Clause 30.4.6)
Imposed Load/
Dead Load
(1)
Ratio ^
h
(2)
Value of a cmin
(3)
0.5
0.5 to 2.0
1.0
0.5
0.6
1.0
0.8
0.7
1.0
1.0
0.7
1.0
1.25
0.8
1.0
2.0
1.2
2.0
0.5
1.3
2.0
0.8
1.5
2=0
1.0
1.6
2.0
1.25
1.9
2.0
2.0
4.9
3.0
0.5
1.8
3.0
0.8
2.0
3.0
1.0
2.3
3.0
1.25
2.8
3.0
2.0
13.0
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
51
30.5 Equivalent Frame Method
30.5.1 Assumptions
The bending moments and shear forces may be
determined by an analysis of the structure as a
continuous frame and the following assumptions may
be made:
a) The structure shall be considered to be made
up of equivalent frames on column lines taken
longitudinally and transversely through the
building. Each frame consists of a row of
equivalent columns or supports, bounded
laterally by the centre-line of the panel on each
side of the centre-line of the columns or
supports. Frames adjacent and parallel to an
edge shall be bounded by the edge and the
centre-line of the adjacent panel.
b) Each such frame may be analyzed in its
entirety, or, for vertical loading, each floor
thereof and the roof may be analyzed
separately with its columns being assumed
fixed at their remote ends. Where slabs are
thus analyzed separately, it may be assumed
in determining the bending moment at a given
support that the slab is fixed at any support
two panels distant therefrom provided the slab
continuous beyond the point.
c) For the purpose of determining relative
stiffness of members, the moment of inertia
of any slab or column may be assumed to be
that of the gross cross-section of the concrete
alone.
d) Variations of moment of inertia along the axis
of the slab on account of provision of drops
shall be taken into account. In the case of
recessed or coffered slab which is made solid
in the region of the columns, the stiffening
effect may be ignored provided the solid part
of the slab does not extend more than 0. 15 / ef ,
into the span measured from the centre-line
of the columns. The stiffening effect of flared
column heads may be ignored.
30.5.2 Loading Pattern
30.5.2.1 When the loading pattern is known, the
structure shall be analyzed for the load concerned.
30.5.2.2 When the live load is variable but does not
exceed three-quarters of the dead load, or the nature
of the live load is such that all panels will be loaded
simultaneously, the maximum moments may be
assumed to occur at all sections when full design live
load is on the entire slab system.
30.5.2.3 For other conditions of live load/dead
load ratio and when all panels are not loaded
simultaneously:
a) maximum positive moment near midspan of
a panel may be assumed to occur when three-
quarters of the full design live load is on the
panel and on alternate panels; and
b) maximum negative moment in the slab at a
support may be assumed to occur when three-
quarters of the full design live load is on the
adjacent panels only.
30.5.2.4 In no case shall design moments be taken to
be less than those occurring with full design live load
on all panels.
30.5.3 Negative Design Moment
30.5.3.1 At interior supports, the critical section for
negative moment, in both the column strip and middle
strip, shall be taken at the face of rectilinear supports,
but in no case at a distance greater than 0.175 l x from
the centre of the column where l x is the length of the
span in the direction moments are being determined,
measured centre-to-centre of supports.
30.5.3.2 At exterior supports provided with brackets
or capitals, the critical section for negative moment
in the direction perpendicular to the edge shall be
taken at a distance from the face of the supporting
element not greater than one-half the projection of
the bracket or capital beyond the face of the
supporting element.
30.5.3.3 Circular or regular polygon shaped supports
shall be treated as square supports having the same area.
30.5.4 Modification of Maximum Moment
Moments determined by means of the equivalent frame
method, for slabs which fulfil the limitations of 30.4
may be reduced in such proportion that the numerical
sum of the positive and average negative moments is
not less than the value of total design moment M o
specified in 30.4.2.2.
30.5.5 Distribution of Pending Moment Across the
Panel Width
30.5.5.1 Column strip: Negative moment at an interior
support
At an interior support, the column strip shall be
designed to resist 75 percent of the total negative
moment in the panel at that support.
30.5.5.2 Column strip; Negative moment at a exterior
support
a) At an exterior support, the column strip shall
be designed to resist the total negative
moment in the panel at that support.
52
NATIONAL BUILDING CODE OF INDIA
b) Where the exterior support consists of a
column or a wall extending for a distance
equal to or greater than three-quarters of the
value of l v the length of span transverse to
the direction moments are being determined,
the exterior negative moment shall be
considered to be uniformly distributed across
the length l r
30.5.5,3 Column strip: Positive moment for each span
For each span, the column strip shall be designed to
resist 60 percent of the total positive moment in the
panel .
30-5.5*4 Moments in the middle strip
The middle strip shall be designed on the following
bases:
a) That portion of the design moment not resisted
by the column strip shall be assigned to the
adjacent middle strips.
b) Each middle strip shall be proportioned to
resist the sum of the moments assigned to its
two half middle strips.
c) The middle strip adjacent and parallel to
an edge supported by a wall shall be
proportioned to resist twice the moment
assigned to half the middle strip
corresponding to the first row of interior
columns.
30.6 Shear in Flat Slab
30.6.1 The critical section for shear shall be at a
distance d/2 from the periphery of the column/capital/
drop panel, perpendicular to the plane of the slab where
d is the effective depth of the section (see Fig. 12).
The shape in plan is geometrically similar to the support
immediately below the slab (see Fig. 13A and
Fig. 13B).
NOTE — For column sections with re-entrant angles,
the critical section shall be taken as indicated in Fig. 13C
andl3D.
30.6.1.1 In the case of columns near the free edge of
a slab, the critical section shall be taken as -shown
in Fig. 14.
30.6.1.2 When openings in flat slabs are located at a
distance less than ten times the thickness of the slab
from a concentrated reaction or when the openings are
located within the column strips, the critical sections
specified in 30.6.1 shall be modified so that the part of
the periphery of the critical section which is enclosed
by radial projections of the openings to the centroid of
the reaction area shall be considered ineffective
(see Fig. 15), and openings shall not encroach upon
column head.
30.6.2 Calculation of Shear Stress
The shear stress T v shall be the sum of the values
calculated according to 30.6.2.1 and 30.6.2.2.
30.6.2.1 The nominal shear stress in flat slabs shall
be taken as V/b Q d where V is the shear force due to
design load, b Q is the periphery of the critical section
and d is the effective depth.
30.6.2.2 When unbalanced gravity load, wind,
earthquake or other forces cause transfer of bending
moment between slab and column, a fraction (1 - a)
of the moment shall be considered transferred by
eccentricity of the shear about the centroid of the
critical section. Shear stresses shall be taken as varying
linearly about the centroid of the critical section. The
value of a shall be obtained from the equation given
in 30.3.3.
30.6.3 Permissible Shear Stress
30.6.3.1 When shear reinforcement is not provided,
the calculated shear stress at the critical section shall
not exceed k s t c ,
where
k
(0.5 + P c ) but not greater than 1, P c being
the ratio of short side to long side of the
column/capital; and
T c = 0.25 yff^ in limit state method of design,
and 0. 16 ^[J~^ in working stress method of
design.
30.6.3.2 When the shear stress at the critical section
exceeds the value given in 30.6.3.1, but less than 1.5 t c
shear reinforcement shall be provided. If the shear
stress 1.5 T c , the flat slab shall be redesigned. Shear
stresses shall be investigated at successive sections
more distant from the support and shear reinforcement
shall be provided up to a section where the shear stress
does not exceed 0.5 T c . While designing the shear
reinforcement, the shear stress carried by the concrete
shall be assumed to be 0.5 \ and reinforcement shall
carry the remaining shear.
30.7 Slab Reinforcement
30.7.1 Spacing
The spacing of bars in a flat slab, shall not exceed 2
times the slab thickness, except where a slab is of
cellular or ribbed construction.
30.7.2 Area of Reinforcement
When drop panels are used, the thickness of drop panel
for determination of area of reinforcement shall be the
lesser of the following:
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
53
L
CRITICAL
SECTION
SUPPORT
.SECTION
d/2
d/2
D
SUPPORT SECTION
COLUMN / COLUMN HEAD
13A
CRITICAL
SECTION ^_ SUPPORT
SECTION
d/2
-~T-\
13B
SUPPORT
SECTION
d/2
r
CRITICAL
SECTION
CRITICAL
SECTION
d/2
d/2
1
13C
13D
S
NOTE — d is the effective depth of the flat slab/drop.
Fig. 13 Critical Sections in Plan for Shear in Flat Slabs
FREE EDGE
FREE
CORNER
I
.♦.■a *'■
'*■ '•:••>■'
d/2
r 1
•CRITICAL
SECTION
V.7V-- :•■;.
d/2
J-
L
COLUMN
CRITICAL
SECTION
14 A
14 B
Fig. 14 Effect of Free Edges on Critical Section for Shear
54
NATIONAL BUILDING CODE OF INDIA
OPENING
SUBTRACT FROM
PERIPHERY
OPENING
CRITICAL
SECTION 1
COLUMN d/2 ■
CRITICAL
SECTION
COLUMN
15A
OPENING
15B
LARGE OPENING
COLUMN
CRITICAL
SECTION
COLUMN
CRITICAL
SECTION
15C
* REGARD OPENING AS FREE EDGE
15D
Fig. 15 Effect of Openings on Critical Section for Shear
a) Thickness of drop, and
b) Thickness of slab plus one quarter the
distance between edge of drop and edge of
capital.
30.7.3 Minimum Length of Reinforcement
a) Reinforcement in flat slabs shall have the
minimum lengths specified in Fig. 16. Larger
lengths of reinforcement shall be provided
when required by analysis.
b) Where adjacent spans are unequal, the
extension of negative reinforcement beyond
each face of the common column shall be
based on the longer span.
c) The length of reinforcement for slabs in
frames not braced against sideways and
for slabs resisting lateral loads shall be
determined by analysis but shall not be less
than those prescribed in Fig. 16.
30.7.4 Anchoring Reinforcement
a) All slab reinforcement perpendicular to a
discontinuous edge shall have an anchorage
(straight, bent or otherwise anchored) past the
internal face of the spandrel beam, wall or
column, of an amount:
1) For positive reinforcement — not less
than 150 mm except that with fabric
reinforcement having a fully welded
transverse wire directly over the support,
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
55
Mark
Length
(NO SUB CONTINUITTY) (CONTINUITTY PROVIDED) (NO SLAB CONTINUITTY:
Bar Length from Face of Support
Minimum Length
Maximum Length
d
0.30 L
e
0.33 / n
0.20 Z n
8
0.24 / n
* Bent bars at exterior supports may be used if a general analysis is made.
NOTE — D is the diameter of the column and the dimension of the rectangular column in the direction under consideration.
Fig. 16 Minimum Bend Joint Location and Extension for
Reinforcement in Flat Slabs
56
NATIONAL BUILDING CODE OF INDIA
it shall be permissible to reduce this
length to one-half of the width of the
support or 50 mm, whichever is greater;
and
2) For negative reinforcement — such that
the design stress is developed at
the internal face, in accordance with
Section 5A (c).
b) Where the slab is not supported by a spandrel
beam or wall, or where the slab cantilevers
beyond the support, the anchorage shall be
obtained within the slab.
30.8 Openings in Flat Slabs
Openings of any size may be provided in the flat slab
if it is shown by analysis that the requirements of
strength and serviceability are met. However, for
openings conforming to the following, no special
analysis is required.
a) Openings of any size may be placed within
the middle half of the span in each direction,
provided the total amount of reinforcement
required for the panel without the opening is
maintained.
b) In the area common to two column strips, not
more than one-eighth of the width of strip in
either span shall be interrupted by the
openings. The equivalent of reinforcement
interrupted shall be added on all sides of the
openings.
c) In the area common to one column strip and
one middle strip, not more than one-quarter
of the reinforcement in either strip shall be
interrupted by the openings. The equivalent
of reinforcement interrupted shall be added
on all sides of the openings.
d) The shear requirements of 30,6 shall be
satisfied.
31 WALLS
31.1 General
Reinforced concrete walls subjected to direct
compression or combined flexure and direct
compression should be designed in accordance
with Section 5 or Annex B provided the vertical
reinforcement is provided in each face. Braced walls
subjected to only vertical compression may be designed
as per empirical procedure given in 31.2. The minimum
thickness of walls shall be 100 mm.
31.1.1 Guidelines or design of walls subjected to
horizontal and vertical loads are given in 31.3.
31.2 Empirical Design Method for Walls Subjected
to Inplane Vertical Loads
31.2.1 Braced Walls
Walls shall be assumed to be braced if they are laterally
supported by a structure in which all the following
apply:
a) Walls or vertical braced elements are arranged
in two directions so as to provide lateral
stability to the structure as a whole.
b) Lateral forces are resisted by shear in the
planes of these walls or by braced elements.
c) Floor and roof systems are designed to
transfer lateral forces.
d) Connections between the wall and the lateral
supports are designed to resist a horizontal
force not less than
1) the simple static reactions to the total
applied horizontal forces at the level of
lateral support; and
2) 2.5 percent of the total vertical load that
the wall is designed to carry at the level
of lateral support.
31.2.2 Eccentricity of Vertical Load
The design of a wall shall take account of the actual
eccentricity of the vertical force subject to a minimum
value of 0.05 t.
The vertical load transmitted to a wall by a
discontinuous concrete floor or roof shall be assumed
to act at one-third the depth of the bearing area
measured from the span face of the wall. Where there is
an in-situ concrete floor continuous over the wall, the
load shall be assumed to act at the centre of the wall.
The resultant eccentricity of the total vertical load on
a braced wall at any level between horizontal lateral
supports, shall be calculated on the assumption that
the resultant eccentricity of all the vertical loads above
the upper support is zero.
31.2.3 Maximum Effective Height to Thickness Ratio
The ratio of effective height to thickness, H w Jt, it shall
not exceed 30.
31.2.4 Effective Height
The effective height of a braced wall shall be taken as
follows:
a) Where restrained against rotation at both ends
by
1) floors 0.75 H or
2) intersecting walls or similar 0.75 L x
members whichever is the
lesser.
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
57
b) Where not restrained against rotation at both
ends by
1) floors 1.0 tf or
2) intersecting walls or similar 1.0 L x
members whichever is the
lesser,
where
H w = Unsupported height of the wall.
L = Horizontal distance between centres of
lateral restraint.
31.2.5 Design Axial Strength of Wall
The design axial strength P uw per unit length of a braced
wall in compression may be calculated from the
following equation:
P = 0.3(f-1.2e-2e )/,
UW v 3. /J Ck
where
t = Thickness of the wall,
e = Eccentricity of load measured at right angles
to the plane of the wall determined in
accordance with 31.2.2, and
e^ = Additional eccentricity due to slenderness
effect taken as H 2 12 500 t.
we
31.3 Walls Subjected to Combined Horizontal and
Vertical Forces
31.3.1 When horizontal forces are in the plane of the
wall, it may be designed for vertical forces in
accordance with 31.2 and for horizontal shear in
accordance with 31.4. In plane bending may be
neglected in case a horizontal cross-section of the wall
is always under compression due to combined effect
of horizontal and vertical loads.
31.3.2 Walls subjected to horizontal forces
perpendicular to the wall and for which the design axial
load does not exceed 0.04 / ck A , shall be designed as
slabs in accordance with the appropriate provisions
given in 23, where A is gross area of the section.
31.4 Design for Horizontal Shear
31.4.1 Critical Section for Shear
The critical section for maximum shear shall be taken
at a distance from the base of 0.5 L w or 0.5 H w
whichever is less.
31.4.2 Nominal Shear Stress
The nominal shear stress t ' in walls shall be obtained
as follows:
x = V ltd
vw u
where
V = Shear force due to design loads,
t = Wall thickness,
d = 0.8 x L w where L w is the length of the wall.
31.4.2.1 Under no circumstances shall the nominal
shear stress t cw in walls exceed 0.17 / ck in limit state
method and 0.12/ ck in working stress method.
31.4.3 Design Shear Strength of Concrete
The design shear strength of concrete in walls, T cw ,
without shear reinforcement shall be taken as below:
a) For H IL < 1
x = (3.0 -HL )K,JfZ
cw v w/ w' 1 V •* C|t
where K is 0.2 in limit state method and 0.13
in working stress method.
For H IL > 1
w w
Lesser of the values calculated from (a) above
and from
(HJL+l)
b)
- -^W^ck
(HJL.-V
where K is 0.045 in limit state method and
0.03 in working stress method, but T cw shall
be not less than K 3 y[f~^ in any case where K 3
is 0.15 in limit state method and 0.10 in
working stress method.
31.4.4 Design of Shear Reinforcement
Shear reinforcement shall be provided to carry a shear
equal to V u - T cw .f(0.8 L w ). In case of working stress
method V u is replaced by V. The strength of shear
reinforcement shall be calculated as per 39.4 or B-5.4
with A av defined as below:
A = P (0.8 L ) t
av w v w'
where P w is determined as follows:
a) For walls where H IL < 1, P shall be the
' ww — w
lesser of the ratios of either the vertical
reinforcement area or the horizontal
reinforcement area to the cross-sectional area
of wall in the respective direction.
b) For walls where H IL > 1, P shall be the
' w w 7 w
ratio of the horizontal reinforcement area to
the cross-sectional area of wall per vertical
metre.
31.5 Minimum Requirements for Reinforcement in
Walls
The reinforcement for walls shall be provided as below:
a) the minimum ratio of vertical reinforcement
to gross concrete area shall be;
1) 0.001 2 for deformed bars not larger
than 16 mm in diameter and with a
58
NATIONAL BUILDING CODE OF INDIA
characteristic strength of 415 N/rnrrr or
greater.
2) 0.001 5 for other types of bars.
3) 0.00 1 2 for welded wire fabric not larger
than 1 6 mm in diameter.
b) Vertical reinforcement shall be spaced not
farther apart than three times the wall
thickness nor 450 mm.
c) The minimum ratio of horizontal
reinforcement to gross concrete area shall
be:
1) 0.002 for deformed bars not larger
than 16 mm in diameter and with a
characteristic strength of 415 N/mm 2 or
greater.
2) 0.002 5 for other types of bars.
3) 0.002 for welded wire fabric not larger
than 16 mm in diameter.
d) Horizontal reinforcement shall be spaced not
farther apart than three times the wall
thickness nor 450 mm.
NOTE — The minimum reinforcement may not always
be sufficient to provide adequate resistance to the effects
of shrinkage and temperature.
3 1 .5.1 For walls having thickness more than 200 mm,
the vertical and horizontal reinforcement shall be
provided in two grids, one near each face of the wall.
31.5.2 Vertical reinforcement need not be enclosed
by transverse reinforcement as given in 25.5.3.2 for
column, if the vertical reinforcement is not greater
than 0.01 times the gross sectional area or where the
vertical reinforcement is not required for compression.
32 STAIRS
32.1 Effective Span of Stairs
The effective span of stairs without stringer beams shall
be taken as the following horizontal distances:
a) Where supported at top and bottom risers by
beams spanning parallel with the risers, the
distance centre-to-centre of beams;
b) Where spanning on to the edge of a landing
slab, which spans parallel, with the risers (see
Fig. 17), a distance equal to the going of the
stairs plus at each end either half the width of
the landing or one metre, whichever is
smaller; and
c) Where the landing slab spans in the same
direction as the stairs, they shall be considered
as acting together to form a single slab and
the span determined as the distance centre-
to-centre of the supporting beams or walls,
the going being measured horizontally.
1
V
1
j 1 1 1 1
L up
i
-X-*UxJ- GOING (G) 4~Y— 1— Y —
X
Y
SPAN IN METRES
< 1 m
< 1 m
G + X + Y
< 1 m
> 1 m
G + X+1
> 1 m
< 1 m
G + Y + 1
> 1 m
>1 m
G + 1 +1
Fig. 17 Effective Span for Stairs Supported at
Each End by Landings Spanning Parallel
with the Risers
32.2 Distribution of Loading on Stairs
In the case of stairs with open wells, where spans partly
crossing at right angles occur, the load on areas
common to any two such spans may be taken as one-
half in each direction as shown in Fig. 18. Where flights
or landings are embedded into walls for a length of
not less than 1 10 mm and are designed to span in the
direction of the flight, a 150 mm strip may be deducted
from the loaded area and the effective breadth of the
section increased by 75 mm for purposes of design (see
Fig. 19).
32.3 Depth of Section
The depth of section shall be taken as the minimum
thickness perpendicular to the soffit of the staircase.
33 FOOTINGS
33.1 General
Footings shall be designed to sustain the applied loads,
moments and forces and the induced reactions and to
ensure that any settlement which may occur shall be
as nearly uniform as possible, and the safe bearing
capacity of the soil is not exceeded {see good practice
[6-5A(35)j }.
33.1.1 In sloped or stepped footings the effective
cross-section in compression shall be limited by the
area above the neutral plane, and the angle of slope or
depth and location of steps shall be such that the design
PART 6 STRUCTURAL DESIGN — SECTION 5 CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
59
-BEAM
DOWN
THE LOAD ON AREAS
COMMON TO TWO
SYSTEMS TO BE TAKEN
AS ONE HALF IN EACH
DIRECTION
Fig. 18 Loading on Stairs with Open Wells
110mm-
-*— 150 mm
Fig. 19 Loading on Stairs Built into Walls
requirements are satisfied at every section. Sloped and
stepped footings that are designed as a unit shall be
constructed to assure action as a unit.
33.1.2 Thickness at the Edge of Footing
In reinforced and plain concrete footings, the thickness
at the edge shall be not less than 150 mm for footings
on soils, nor less than 300 mm above the tops of piles
for footings on piles.
33.1.3 In the case of plain concrete pedestals, the angle
between the plane passing through the bottom edge of
the pedestal and the corresponding junction edge of
the column with pedestal and the horizontal plane {see
Fig. 20) shall be governed by the expression:
100 q Q
tan a £o.9j + 1
Jck
60
NATIONAL BUILDING CODE OF INDIA
where
4
Calculated maximum bearing pressure at the
base of the pedestal in N/mm 2 , and
Characteristic strength of concrete at 28 days
in N/mm 2
COLUMN
' Y a
titt
-PLAIN CONCRETE
PEDESTAL
Fig. 20
33.2 Moments and Forces
33.2.1 In the case of footings on piles, computation
for moments and shears may be based on the
assumption that the reaction from any pile is
concentrated at the centre of the pile.
33.2.2 For the purpose of computing stresses in
footings which support a round or octagonal concrete
column or pedestal, the face of the column or pedestal
shall be taken as the side of a square inscribed within
the perimeter of the round or octagonal column or
pedestal.
33.2.3 Bending Moment
33.2.3.1 The bending moment at any section shall be
determined by passing through the section a vertical
plane which extends completely across the footing, and
computing the moment of the forces acting over the
entire area of the footing on one side of the said plane.
33.2.3.2 The greatest bending moment to be used in
the design of an isolated concrete footing which
supports a column, pedestal or wall, shall be the
moment computed in the manner prescribed in 33.2.3.1
at sections located as follows:
a) At the face of the column, pedestal or wall,
for footings supporting a concrete column,
pedestal or wall;
b) Halfway between the centre-line and the edge
of the wall, for footings under masonry walls;
and
c) Halfway between the face of the column or
pedestal and the edge of the gussetted base,
for footings under gussetted bases.
33.2.4 Shear and Bond
33.2.4.1 The shear strength of footings is governed
by the more severe of the following two conditions:
a) the footing acting essentially as a wide beam,
with a potential diagonal crack extending in
a plane across the entire width; the critical
section for this condition shall be assumed as
a vertical section located from the face of the
column, pedestal or wall at a distance equal
to the effective depth of footing in case of
footings on soils, and at a distance equal to
half the effective depth of footing for footings
on piles.
b) Two-way action of the footing, with potential
diagonal cracking along the surface of
truncated cone or pyramid around the
concentrated load; in this case, the footing
shall be designed for shear in accordance with
appropriate provisions specified in 30.6.
33.2.4.2 In computing the external shear on any
section through a footing supported on piles, the entire
reaction from any pile of diameter D whose centre is
located D 12 or more outside the section shall be
p
assumed as producing shear on the section; the reaction
from any pile whose centre is located D 12 or more
inside the section shall be assumed as producing no
shear on the section. For intermediate positions of the
pile centre, the portion of the pile reaction to be
assumed as producing shear on the section shall be
based on straight line interpolation between full value
at D 12 outside the section and zero value at D/2 inside
p p
the section.
33.2.4.3 The critical section for checking the
development length in a footing shall be assumed at
the same planes as those described for bending moment
in 33.2.3 and also at all other vertical planes where
abrupt changes of section occur. If reinforcement is
curtailed, the anchorage requirements shall be checked
in accordance with 25.2.3.
33.3 Tensile Reinforcement
The total tensile reinforcement at any section shall
provide a moment of resistance at least equal to the
bending moment on the section calculated in
accordance with 33.2.3.
33.3.1 Total tensile reinforcement shall be distributed
across the corresponding resisting section as given
below:
a) In one-way reinforced footing, the
reinforcement extending in each direction
shall be distributed uniformly across the full
width of the footing;
b) In two-way reinforced square footing, the
reinforcement extending in each direction
shall be distributed uniformly across the full
width of the footing; and
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
61
c) In two-way reinforced rectangular footing, the
reinforcement in the long direction shall be
distributed uniformly across the full width of
the footing. For reinforcement in the short
direction, a central band equal to the width of
the footing shall be marked along the length
of the footing and portion of the reinforcement
determined in accordance with the equation
given below shall be uniformly distributed
across the central band:
Reinforcement in central band width 2
Total reinforcement in short direction /? + 1
where /? is the ratio of the long side to the
short side of the footing. The remainder of the
reinforcement shall be uniformly distributed
in the outer portions of the footing.
33.4 Transfer of Load at the Base of Column
The compressive stress in concrete at the base of a
column or pedestal shall be considered as being
transferred by bearing to the top of the supporting
pedestal or footing. The bearing pressure on the loaded
area shall not exceed the permissible bearing stress in
direct compression multiplied by a value equal to
f * but not greater than 2;
where
A { = Supporting area for bearing of footing,
which in sloped or stepped footing may be
taken as the area of the lower base of the
largest frustum of a pyramid or cone
contained wholly within the footing and
having for its upper base, the area actually
loaded and having side slope of one vertical
to two horizontal; and
A 2 = Loaded area at the column base.
For working stress method of design the permissible
bearing stress on full area of concrete shall be taken
as 0.25 / ck ; for limit state method of design the
permissible bearing stress shall be 0.45 /
33.4.1 Where the permissible bearing stress on the
concrete in the supporting or supported member would
be exceeded, reinforcement shall be provided for
developing the excess force, either by extending the
longitudinal bars into the supporting member, or by
dowels (see 33.4.3).
33.4.2 Where transfer of force is accomplished by
reinforcement, the development length of the
reinforcement shall be sufficient to transfer the
compression or tension to the supporting member in
accordance with 25.2.
33.4.3 Extended longitudinal reinforcement or dowels
of at least 05 percent of the cross-sectional area of the
supported column or pedestal and a minimum of four
bars shall be provided. Where dowels are used, their
diameter shall not exceed the diameter of the column
bars by more than 3 mm.
33.4.4 Column bars of diameters larger than 36 mm,
in compression only can be dowelled at the footings
with bars of smaller size of the necessary area. The
dowel shall extend into the column, a distance equal
to the development length of the column bar and into
the footing, a distance equal to the development length
of the dowel.
33.5 Nominal Reinforcement
33.5.1 Minimum reinforcement and spacing shall be
as per the requirements of solid slab.
33.5.2 The nominal reinforcement for concrete
sections of thickness greater than 1 m shall be 360 mm 2
per metre length in each direction on each face. This
provision does not supersede the requirement of
minimum tensile reinforcement based on the depth of
the section.
SECTION 5A (e) STRUCTURAL DESIGN
(LIMIT STATE METHOD)
34 SAFETY AND SERVICEABILITY
REQUIREMENTS
34.1 General
In the method of design based on limit state concept,
the structure shall be designed to withstand safely all
loads liable to act on it throughout its life; it shall also
satisfy the serviceability requirements, such as
limitations on deflection and cracking. The acceptable
limit for the safety and serviceability requirements
before failure occurs is called a 'limit state'. The aim
of design is to achieve acceptable probabilities that the
structure will not become unfit for the use for which it
is intended, that is, that it will not reach a limit state.
34.1.1 All relevant limit stales shall be considered in
design to ensure an adequate degree of safety and
serviceability. In general, the structure shall be
designed on the basis of the most critical limit state
and shall be checked for other limit states.
34.1.2 For ensuring the above objective, the design
should be based on characteristic values for material
strengths and applied loads, which take into account
the variations in the material strengths and in the loads
to be supported. The characteristic values should be
based on statistical data if available; where such data
are not available they should be based on experience.
62
NATIONAL BUILDING CODE OF INDIA
The 'design values' are derived from the characteristic
values through the use of partial safety factors, one
for material strengths and the other for loads. In the
absence of special considerations these factors should
have the values given in 35 according to the material,
the type of loading and the limit state being considered.
34.2 Limit State of Collapse
The limit state of collapse of the structure or part of
the structure could be assessed from rupture of one or
more critical sections and from buckling due to elastic
or plastic instability (including the effects of sway
where appropriate) or overturning. The resistance to
bending, shear, torsion and axial loads at every section
shall not be less than the appropriate value at that
section produced by the probable most unfavourable
combination of loads on the structure using the
appropriate partial safety factors.
34.3 Limit States of Serviceability
34.3.1 Deflection
Limiting values of deflections are given in 22.2.
34.3.2 Cracking
Cracking of concrete should not adversely affect the
appearance or durability of the structure; the acceptable
limits of cracking would vary with the type of structure
and environment. Where specific attention is required
to limit the designed crack width to a particular value,
crack width calculation may be done using formula
given in Annex F.
The practical objective of calculating crack width is
merely to give guidance to the designer in making
appropriate structural arrangements and in avoiding
gross errors in design, which might result in
concentration and excessive width of flexural crack.
The surface width of the cracks should not, in general,
exceed 0.3 mm in members where cracking is not
harmful and does not have any serious adverse effects
upon the preservation of reinforcing steel nor upon the
durability of the structures. In members where cracking
in the tensile zone is harmful either because they are
exposed to the effects of the weather or continuously
exposed to moisture or in contact soil or ground
water, an upper limit of 0.2 mm is suggested for the
maximum width of cracks. For particularly aggressive
environment, such as the 'sever' category in Table 3,
the assessed surface width of cracks should not in
general, exceed 0.1 mm.
34.4 Other Limit States
Structures designed for unusual or special functions
shall comply with any relevant additional limit state
considered appropriate to that structure.
35 CHARACTERISTIC AND DESIGN VALUES
AND PARTIAL SAFETY FACTORS
35.1 Characteristic Strength of Materials
The term 'characteristic strength' means that value of
the strength of the material below which not more than
5 percent of the test results are expected to fall. The
characteristic strength for concrete shall be in
accordance with Table 2. Until the relevant Indian
Standard Specifications for reinforcing steel are
modified to include the concept of characteristic
strength, the characteristic value shall be assumed as
the minimum yield stress/0.2 percent proof stress
specified in the relevant Indian Standard Specifications.
35.2 Characteristic Loads
The term * characteristic load* means that value of load
which has a 95 percent probability of not being
exceeded during the life of the structure. Since data
are not available to express loads in statistical terms,
for the purpose of this Section, dead loads, imposed
loads, wind loads, snow load in accordance with the
good practice [6-5A(33)] and seismic forces in
accordance with the good practice [6-5A(34)] shall be
assumed as the characteristic loads.
35.3 Design Values
35.3.1 Materials
The design strength of the materials, f d is given by
/
/,.=-
where
/ = Characteristic strength of the material (see
35.1), and
7 m = Partial safety factor appropriate to the
material and the limit state being considered.
35.3.2 Loads
The design load, F d is given by
f* =py {
where
F = Characteristic load (see 35.2), and
7 f = Partial safety factor appropriate to the
nature of loading and the limit state being
considered.
35.3.3 Consequences of Attaining Limit State
Where the consequences of a structure attaining a limit
state are of a serious nature such as huge loss of life
and disruption of the economy, higher values for y f
and 7 m than those given under 35.4.1 and 35.4.2 may
be applied.
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
63
35.4 Partial Safety Factors
35.4.1 Partial Safety Factor Y f for Loads
The values 7 f given in Table 1 8 shall normally be used.
Table 18 Values of Partial Safety Factor y f
for Loads
(Clauses 17.2.3.1, 35.4.1 andB-43)
Load
Combination
Limit State of
Collapse
Limit States of
Serviceability
(1)
DL
(2)
IL
(3)
WL
(4)
DL
(5)
IL
(6)
WL
(7)
1.5
LO
1.0
1.0
1.0
0.8
DL+IL
DL+WL
1.5 oi
0.9 1 '
1.5
1.0
DL+ IL+ WL
/-"
1.2
^
0.8
NOTES
1 While considering earthquake effects, substitute EL for WL.
2 For the limit states of serviceability, the values of y f given in
this table are applicable for short-term effects. While assessing
the long-term effects due to creep the dead load and that part of
the live load likely to be permanent may only be considered.
] This value is to be considered when stability against overturning
or stress reversal is critical.
35.4.2 Partial Safety Factor y m for Material Strength
35.4.2.1 When assessing the strength of a structure or
structural member for the limit state of collapse, the
values of partial safety factor, y m should be taken as 1 .5
for concrete and 1.15 for steel.
NOTE — / values are already incorporated in the equations
and tables given in this Section for limit state design.
35.4.2.2 When assessing the deflection, the material
properties such as modulus of elasticity should be taken
as those associated with the characteristic strength of
the material.
36 ANALYSIS
36,1 Analysis of Structure
Method of analysis as in 21 shall be used. The material
strength to be assumed shall be characteristic values
in the determination of elastic properties of members
irrespective of the limit state being considered.
Redistribution of the calculated moments may be made
as given in 36.1.1.
36.1.1 Redistribution of Moments in Continuous
Beams and Frames
The redistribution of moments may be carried out
satisfying the following conditions:
a) Equilibrium between the internal forces and
the external loads is maintained.
b) The ultimate moment of resistance provided
at any section of a member is not less than 70
percent of the moment at the section obtained
from an elastic maximum moment diagram
covering all appropriate combinations of
loads.
c) The elastic moment at any section in a
member due to a particular combination of
loads shall not be reduced by more than 30
percent of the numerically largest moment
given anywhere by the elastic maximum
moments diagram for the particular member,
covering all appropriate combination of loads.
d) At sections where the moment capacity after
redistribution is less than that from the elastic
maximum moment diagram, the following
relationship shall be satisfied:
5l + M< .6
d 100
where
;c u = Depth of neutral axis,
d - Effective depth, and
8M - Percentage reduction in moment.
e) In structures in which the structural frame
provides the lateral stability, the reduction
in moment allowed by condition given
in 36.1.1 (c) shall be restricted to 10 percent
for structures over 4 storeys in height.
36.1.2 Analysis of Slabs Spanning in Two Directions
at Right Angles
Yield line theory or any other acceptable method
may be used. Alternatively the provisions given in
Annex D may be followed.
37 LIMIT STATE OF COLLAPSE: FLEXURE
37.1 Assumptions
Design for the limit state of collapse in flexure shall
be based on the assumptions given below:
a) Plane sections normal to the axis remain plane
after bending.
b) The maximum strain in concrete at the
outermost compression fibre is taken as
0.003 5 in bending.
c) The relationship between the compressive
stress distribution in concrete and the strain
in concrete may be assumed to be rectangle,
trapezoid, parabola or any other shape which
result in prediction of strength in substantial
agreement with the results of test. An
64
NATIONAL BUILDING CODE OF INDIA
acceptable stress strain curve is given in
Fig. 2 1 . For design purposes, the compressive
strength of concrete in the structure shall be
assumed to be 0.67 times the characteristic
strength. The partial safety factory =1.5 shall
be applied in addition to this.
NOTE — For the stress- strain curve in Fig. 2 1 the design
stress block parameters are as follows (see Fig. 22).
Area of stress block = 0.36/\.;t
Depth of centre of compressive force = 0.42 x
from the extreme fibre in compression
where
/ ck = Characteristic compressive strength of concrete,
and
* u = Depth of neutral axis.
/,
- + 0.002
0.67 fck
0.67fck/rm
0.002 0.0035
STRAIN — m~
Fig. 21 Stress-Strain Curve for Concrete
Fig. 22 Stress Block Parameters
d) The tensile strength of the concrete is ignored.
e) The stresses in the reinforcement are derived
from representative stress-strain curve for the
type of steel used. Typical curves are given
in Fig. 23. For design purposes the partial
safety factor y m , equal to 1 . 1 5 shall be applied.
f) The maximum strain in the tension
reinforcement in the section at failure shall
not be less than:
1.15 E.
where
/ = Characteristic strength of steel, and
E s = Modulus of elasticity of steel.
NOTE — The limiting values of depth of neutral axis
for different grades of steel based on the assumptions
of 37.1 are as follows:
/>
250
415
500
Xv, maw «
0.53
0.48
0.46
The expression for obtaining the moments of resistance
for rectangular and T-Sections, based on the
assumptions of 37.1, are given in Annex G.
38 LIMIT STATE OF COLLAPSE:
COMPRESSION
38.1 Assumptions
In addition to the assumptions given in 37.1(a) to 37.1(e)
for flexure, the following shall be assumed:
a) The maximum compressive strain in concrete
in axial compression is taken as 0.002.
b) The maximum compressive strain at the
highly compressed extreme fibre in concrete
subjected to axial compression and bending
and when there is no tension on the section
shall be 0.003 5 minus 0.75 times the strain
at the least compressed extreme fibre.
38.2 Minimum Eccentricity
All members in compression shall be designed for the
minimum eccentricity in accordance with 24.4. Where
calculated eccentricity is larger, the minimum
eccentricity should be ignored.
38.3 Short Axially Loaded Members in Compression
The member shall be designed by considering
the assumptions given in 38.1 and the minimum
eccentricity. When the minimum eccentricity as
per 24.4 does not exceed 0.05 times the lateral
dimension, the members may be designed by the
following equation:
P =0.4 /..A +0.67/.A, r
u •'ck c J y sc
where
P = Axial load on the member,
u
/ = Characteristic compressive strength of the
concrete,
A = Area of concrete
c
/ = Characteristic strength of the compression
reinforcement, and
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
65
ty
0.975fy ^
0.95fy yf\ I
0.90fy -//I I
0.85fy |~ Jj ,/ ,
nftnfv/
fy
fy/ 1.15
Es = 200000 N/mm 2
23A COLD WORKED DEFORMED BAR
LU
\-
co
f.q = 9nn nnn n / mm 2
fy/ 1.15
STRAIN
23B STEEL BAR WITH DEFINITE YIELD POINT
Fig. 23 Representative Stress-Strain Curves for Reinforcement
A sc = Area of longitudinal reinforcement for
columns.
38.4 Compression Members with Helical
Reinforcement
The strength of compression members with helical
reinforcement satisfying the requirement of 38.4.1
shall be taken as 1.05 times the strength of similar
member with lateral ties.
38.4.1 The ratio of the volume of helical reinforcement
to the volume of the core shall not be less than
0.36(A g /A-l)/ ck // y
where
A g = Gross area of the section,
A c = Area of the core of the helically reinforced
column measured to the outside diameter of
the helix,
66
NATIONAL BUILDING CODE OF INDIA
/ ck = Characteristic compressive strength of the
concrete, and
/ = Characteristic strength of the helical
reinforcement but not exceeding 415 N/mm 2 .
38.5 Members Subjected to Combined Axial Load
and Uniaxial Bending
A member subjected to axial force and uniaxial bending
shall be designed on the basis of 38.1 and 38.2.
NOTE — The design of member subject to combined axial
load and uniaxial bending will involve lengthy calculation by
trial and error. In order to overcome these difficulties
interaction diagrams may be used. These have been prepared
and published by BIS in SP 16 'Design aids for reinforced
concrete to IS 456'.
38.6 Members Subjected to Combined Axial Load
and Biaxial Bending
The resistance of a member subjected to axial force
and biaxial bending shall be obtained on the basis of
assumptions given in 38.1 and 38.2 with neutral axis
so chosen as to satisfy the equilibrium of load and
moments about two axes. Alternatively such members
may be designed by the following equation:
M..
M
uyl
<1.0
where
M ,M
M ,,M
= Moments about x and y axes due to
design loads,
= Maximum uniaxial moment capacity
for an axial load of P u , bending about
x and v axes respectively, and« n is
related to P IP
where
P =0.45/,. A +0.75/. A
uz •'ck c •'y sc
For values ofPJP uz = 0.2 to 0.8, the values of a n vary
linerly from 1.0 to 2.0. For values less than 0.2 a n is
1 .0; for values greater than 0.8, oe n is 2.0.
38.7 Slender Compression Members
The design of slender compression members
(see 24.1.1) shall be based on the forces and the
moments determined from an analysis of the structure,
including the effect of deflections on moments and
forces. When the effect of deflections are not taken
into account in the analysis, additional moment given
in 38.7.1 shall be taken into account in the appropriate
direction.
38.7.1 The additional moments M ax and M a shall be
calculated by the following formulae:
PD
M = u
" 2000
V
_D_
2
M = P " b
w
2
" y 2000
lb J
where
P u = Axial load on the member,
/ ex = Effective length in respect of the major axis,
/ = Effective length in respect of the minor axis,
D = Depth of the cross-section at right angles to
the major axis, and
b = Width of the member.
For design of section, 38.5 or 38.6 as appropriate shall
apply.
NOTES
1 A column may be considered braced in a given plane if lateral
stability to the structure as a whole is provided by walls or
bracing or buttressing designed to resist all lateral forces in that
plane. It should otherwise be considered as unbraced.
2 In the case of a braced column without any transverse loads
occurring in its height, the additional moment shall be added to
an initial moment equal to sum of 0.4 Af ul and 0.6 Af u2 where
M u2 is the larger end moment and M Ql is the smaller end moment
(assumed negative if the column is bent in double curvature).
In no case shall the initial moment be less than 0.4 Af u2 nor the
total moment including the initial moment be less than Af u2 . For
unbraced columns, the additional moment shall be added to the
end moments.
3 Unbraced compression members, at any given level or storey,
subject to lateral load are usually constrained to deflect equally.
In such cases slenderness ratio for each column may be taken
as the average for all columns acting in the same direction.
38.7.1.1 The values given by equation 38.7.1 may be
multiplied by the following factor:
P -P
K-Py>
where
P u ~ Axial load on compression member,
P = As defined in 38.6, and
uz '
P b = Axial load corresponding to the condition
of maximum compressive strain of 0.003 5
in concrete and tensile strain of 0.002 in
outer most layer of tension steel.
39 LIMIT STATE OF COLLAPSE: SHEAR
39.1 Nominal Shear Stress
The nominal shear stress in beams of uniform depth
shall be obtained by the following equation:
v bd
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
67
where
V u = Shear force due to design loads;
b = Breadth of the member, which for flanged
section shall be taken as the breadth of the
web, & w ; and
d - Effective depth.
39.1.1 Beams of Varying Depth
In the case of beams of varying depth the equation
shall be modified as:
39.2.1.1 For solid slabs, the design shear strength for
concrete shall be x c k, where k has the values given
below:
Overall 300
Depth of or
Slab, mm more
k LOO
275 250 225 200 175
150
or
less
1.05 1.10 1.15 1.20 1.25 1.30
T„ =
M
V B ±-Manj3
a
bd
where
T , V , b and d are the same as in 39.1,
v' u' '
M u = Bending moment at the section, and
)3 = Angle between the top and the bottom edges
of the beam.
The negative sign in the formula applies when the
bending moment M u increases numerically in the same
direction as the effective depth d increases, and the
positive sign when the moment deceases numerically
in this direction.
39.2 Design Shear Strength of Concrete
39.2.1 The design shear strength of concrete in beams
without shear reinforcement is given in Table 19.
NOTE — This provision shall not apply to flat slabs for which
30.6 shall apply
39.2.2 Shear Strength of Members under Axial
Compression
For members subjected to axial compression P u , the
design shear strength of concrete, given in Table 19,
shall be multiplied by the following factor:
5=1 +
■ V*
but not exceeding 1.5
where
P u = Axial compressive force in Newtons,
A = Gross area of the concrete section in mm 2 ,
and
f ck = Characteristic compressive strength of
concrete.
39.2.3 With Shear Reinforcement
Under no circumstances, even with shear reinforcement,
Table 19 Design Shear Strength of Concrete, t c , N/mm 2
(Clauses 39.2.1, 39.2.2, 39.3, 39.4, 39.5.3, 40.3.2, 40.3.3 and 40.4.3)
A o
100-5-
bd
Concrete Code
M15
M20
M25
M30
M35
M 40 and above
(1)
(2)
(3)
(4)
(5)
(6)
(7)
<0.15
0.28
0.28
0.29
0.29
0.29
0.30
0.25
0.35
0.36
0.36
0.37
0.37
0.38
0.50
0.46
0.48
0.49
0.50
/ 0.50
0.51
0.75
0.54
0.56
0.57
0.59
., 0.59
0.60
1.00
0.60
0.62
0.64
0.66
, 0.67
0.68
1.25
0.64
0.67
0.70
0.71
>0.73
0.74
1.50
0.68
0.72
0.74
0.76
0.78
0.79
1.75
0.71
0.75
0.78
0.80
0.82
0.84
2.00
0.71
0.79
0.82
0.84
0.86
0.88
2.25
0.71
0.81
0.85
0.88
0.90
0.92
2.50
0.71
0.82
0.88
0.91
0.93
0.95
2.75
0,71
0.82
0.90
0.94
0.%
0.98
3.00
0.71
0.82
0.92
0.%
0,99
1.01
and above
NOTE — The term A g is the area of longitudinal tension reinforcement which continues at least one effective depth beyond the
section being considered except at support where the full area of tension reinforcement may be used provided the detailing conforms
to 25.2.2 and 25.2.3.
68
NATIONAL BUILDING CODE OF INDIA
shall be nominal shear stress in beams x exceed x
v c max
given in Table 20.
39.2.3.1 For solid slabs, the nominal shear stress shall
not exceed half the appropriate values given in
Table 20.
Table 20 Maximum Shear Stress, T ,N/mm 2
7 c max'
(Clauses 39.2.3, 39.2.3.1, 39.5.1 and 40.3.1)
Concrete M 15 M20 M 25 M 30 M 35 M 40 and
Grade above
fcmax, 2.5 2.8 3.1 3.5 3.7 4.0
N/mm 2
39.3 Minimum Shear Reinforcement
When t v is less than t c given in Table 19, minimum
shear reinforcement shall be provided in accordance
with 25.5.1.6.
39.4 Design of Shear Reinforcement
When T v exceeds x given in Table 19, shear
reinforcement shall be provided in any of the following
forms:
a) Vertical stirrups,
b) Bent-up bars along with stirrups, and
c) Inclined stirrups
Where bent-up bars are provided, their contribution
towards shear resistance shall not be more than half
that of the total shear reinforcement.
Shear reinforcement shall be provided to carry a shear
equal to V -ibd. The strength of shear reinforcement
V us shall be calculated as below:
a) For vertical stirrups:
_ 0-87 f y A„d
b) For inclined stirrups or a series of bars bent-
up at different cross-sections:
0.87 f Ad
V us = y v (sin a + cos a)
S v
c) For single bar or single group of parallel bars,
all bent-up at the same cross-section:
V =0.87/ A sincr
US J V sv
where
A sv = Total cross-sectional area of stirrup legs or
bent-up bars within a distance s ,
S v = Spacing of the stirrups or bent-up bars along
with the length of the member,
x = Nominal shear stress,
x c = Design shear strength of the concrete,
b = Breadth of the member which for flanged
beams, shall be taken as the breadth of the
web b ,
/ = Characteristic strength of the stirrup or bent-
up reinforcement which shall not be taken
greater than 415 N/mm 2 ,
a = Angle between the inclined stirrup or bent-
up bar and the axis of the member, not less
than 45°, and
d = Effective depth.
NOTES
1 Where more than one type of shear reinforcement is used
to reinforce the same portion of the beam, the total shear
resistance shall be computed as the sum of the resistance for
the various types separately.
2 The area of the stirrups shall not be less than the minimum
specified in 25.5.1.6.
39.5 Enhanced Shear Strength of Sections Close to
Supports
39.5.1 General
Shear failure at sections of beams and cantilevers
without shear reinforcement will normally occur on
plane inclined at an angle 30° to the horizontal. If the
angle of failure plane is forced to be inclined more
steeply than this [because the section considered
(X - X) in Fig. 24 is close to a support or for other
reasons], the shear force required to produce failure is
increased.
The enhancement of shear strength may be taken into
account in the design of sections near a support by
increasing design shear strength of concrete
to 2d %Ja s provided that design shear stress at the face
of the support remains less than the values given in
Table 20. Account may be taken of the enhancement
in any situation here the section considered is closer
to the face of a support or concentrated load than twice
the effective depth, d. To be effective, tension
reinforcement should extend on each side of the point
where it is intersected by a possible failure plane for a
distance at least equal to the effective depth, or be
provided with an equivalent^^nchorage.
39.5.2 Shear Reinforcement for Sections Close to
Supports
If shear reinforcement is required, the total area of this
is given by
A = a v b(x w - 2 d%Ja w )/0.Slf y > 0.4 a y b/0.Slf y
This reinforcement should be provided within the
middle three quarters of a v , where a y is less than d,
horizontal shear reinforcement will be effective than
vertical.
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
69
'I
NOTE — The shear causing failure is that acting on Section X - X.
Fig. 24 Shear Failure Near Supports
39.5.3 Enhanced Shear Strength Near Supports
(Simplified Approach)
The procedure given in 39.5.1 and 39.5.2 may be used
for all beams. However for beams carrying generally
uniform load or where the principal load is located
farther than 2d from the face of support, the shear stress
may be calculated at a section a distance d from the
face of support. The value of x c is calculated in
accordance with Table 19 and appropriate shear
reinforcement is provided at sections closer to the
support, no further check for shear at such sections is
required.
40 LIMIT STATE OF COLLAPSE: TORSION
40.1 General
In structures, where torsion is required to maintain
equilibrium, members shall be designed for torsion in
accordance with 40.2 to 40.4. However, for such
indeterminate structures where torsion can be
eliminated by releasing redundant restraints, no specific
design for torsion is necessary, provided torsional
stiffness is neglected in the calculation of internal
forces. Adequate control of any torsional cracking is
provided by the shear reinforcement as per 39.
NOTE — The approach to design in this clause is as follows:
Torsional reinforcement is not calculated separately from that
required for bending and shear. Instead the total longitudinal
reinforcement is determined for a fictitious bending moment
which is a function of actual bending moment and torsion;
similarly web reinforcement is determined for a fictitious shear
which is a function of actual shear and torsion.
40.1.1 The design rules laid down in 40.3 and 40.4
shall apply to beams of solid rectangular cross-section.
However, these clauses may also be applied to flanged
beams, by substituting b w for b in which case they are
generally conservative; therefore specialist literature
may be referred to.
40.2 Critical Section
Sections located less than a distance d, from the face
of the support may be designed for the same torsion
as computed at a distance d, where d is the effective
depth.
40.3 Shear and Torsion
40.3.1 Equivalent Shear
Equivalent shear V e , shall be calculated from the
formula:
V e =V u +1.6-=-
b
where
V = Equivalent shear,
V = Shear,
u '
x = Torsional moment, and
u '
b = Breadth of beam.
The equivalent nominal shear stress x ve in this case
shall be calculated as given in 40.1, except for
substituting V u by V e . The values of x ve shall not exceed
the values of x given in Table 20.
c max o
70
NATIONAL BUILDING CODE OF INDIA
40.3.2 If the equivalent nominal shear stress T ve does
not exceed % c given in Table 19, minimum shear
reinforcement shall be provided as per 25.5.1.6.
40.3.3 If x ve exceeds x c given in Table 19, both
longitudinal and transverse reinforcement shall be
provided in accordance with 40.4.
40.4 Reinforcement in Members Subjected to
Torsion
40.4.1 Reinforcement for torsion, when required, shall
consist of longitudinal and transverse reinforcement.
40.4.2 Longitudinal Reinforcement
The longitudinal reinforcement shall be designed to
resist an equivalent bending moment, M d , given by
M d = M a+ M,
where
M u = Bending moment at the cross-section, and
(l + D/6)
M L =T U -
1.7
where
T u is the torsional moment, D is the overall depth
of the beam and b is the breadth of the beam.
40.4.2.1 If the numerical value of M t as defined
in 40.4.2 exceeds the numerical value of the moment
M u , longitudinal reinforcement shall be provided on
the flexural compression face, such that the beam
can also withstand an equivalent M e2 given by
M c2 = Af t - Af , the moment M e2 being taken as acting
in the opposite sense to the moment Af .
40.4.3 Transverse Reinforcement
Two legged closed hoops enclosing the corner
longitudinal bars shall have an area of cross-section
A given by
T u S v
V u s v
V,(0.87/ y ) 2.54(0.87/ y )
but the total transverse reinforcement shall not be less
than
(T w -T c )fr.J T
0.87/ v
where
T a = Torsional moment,
V = Shear force,
s v = Spacing of the stirrup reinforcement,
b x = Centre-to-centre distance between corner
bars in the direction of the width,
d l = Centre-to-centre distance between corner
bars,
b = Breadth of the member,
f y - Characteristic strength of the stirrup
reinforcement,
x ve = Equivalent shear stress as specified
in 40.3.1, and
x c = Shear strength of the concrete as per
Table 19.
41 LIMIT STATE OF SERVICEABILITY:
DEFLECTION
41.1 Flexural Members
In all normal cases, the deflection of a flexural member
will not be excessive if the ratio of its span to its
effective depth is not greater than appropriate ratios
given in 22.2.1. When deflections are calculated
according to Annex C, they shall not exceed the
permissible values given in 22.2.
42 LIMIT STATE OF SERVICEABILITY:
CRACKING
42.1 Flexural Members
In general, compliance with the spacing requirements
of reinforcement given in 25.3*2 should be sufficient
to control flexural cracking. If greater spacing are
required, the expected crack width should be checked
by formula given in Annex F.
42.2 Compression Members
Cracks due to bending in a compression member
subjected to a design axial load greater than 0.2/ ck A c ,
where / ck is the characteristic compressive strength of
concrete and A c is the area of the gross section of the
member, need not be checked A member subjected to
lesser load than 0.2/^ A c may be considered as flexural
member for the purpose of crack control (see 42.1).
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
71
ANNEX A
{Foreword)
SELF COMPACTING CONCRETE
A-l Self compacting concrete is concrete that is
able to flow under its own weight and completely
fill the formwork, even in the presence of dense
reinforcement, without segregation, whilst maintaining
homogeneity.
A-2 APPLICATION AREA
Self compacting concrete may be used in precast-
applications or for concrete placed on site. It can be
manufactured in a site batching plant or in a ready mix
concrete plant and delivered to site by truck. It can
then be placed either by pumping or pouring into
horizontal or vertical structures. In designing the mix,
the size and the form of the structure, the dimension
and density of reinforcement and cover should be taken
in consideration.
A-3 CHARACTERISTICS OF FRESH SELF
COMPACTING CONCRETE
The level of fluidity of self compacting concrete
is governed chiefly by the dosing and type of
superplasticizer. Due to the high fluidity of self
compacting concrete, the risk of segregation and
blocking is very high. Preventing segregation is
therefore an important feature of the control regime.
The tendency to segregation can be reduced by the
use of a sufficient amount of fines (< 0.125 mm), or
using a Viscosity Modifying Admixture (VMA).
Features of fresh self compacting concrete
a) Slump about 600 mm
b) Sufficient amount of fines (<0.125 mm)
c) Use of Viscosity Modifying Admixture
d) Segregation resistance
ANNEX B
{Clauses 1722, 21.3.1, 21.7, 25.2.1 and 31.1)
STRUCTURAL DESIGN (WORKING STRESS METHOD)
B-l GENERAL
B-l.l General Design Requirements
The general design requirements of Section 3 shall
apply to this Annex.
B-1.2 Redistribution of Moments
Except where the simplified analysis using coefficients
(see 21.5) is used, the moments over the supports for
any assumed arrangement of loading, including the
dead load moments may each be increased or decreased
by not more than 15 percent, provided that these
modified moments over the supports are used for the
calculation of the corresponding moments in the spans.
B-1.3 Assumptions for Design of Members
In the methods based on elastic theory, the following
assumptions shall be made:
a) At any cross-section, plane sections before
bending remain plain after bending.
b) All tensile stresses are taken up by reinforcement
and none by concrete, except as otherwise
specifically permitted.
c) The stress-strain relationship of steel and
concrete, under working loads, is a straight
line.
d) The modular ratio m has the value
280
3a„ k „
where a cbc is permissible compressive stress due
to bending in concrete in N/mm 2 as specified in
Table 21.
NOTE — The expression given for m partially takes into
account long-term effects such as creep. Therefore this m is
not the same as the modular ratio derived based on the value
of E c given in 5.2.3.1.
B-2 PERMISSIBLE STRESSES
B-2.1 Permissible Stresses in Concrete
Permissible stresses for the various grades of concrete
shall be taken as those given in Tables 21 and 23.
NOTE — For increase in strength with age 5.2.1 shall be
applicable. The values of permissible stress shall be obtained
by interpolation between the grades of concrete.
B-2.1. 1 Direct Tension
For members in direct tension, when full tension is
taken by the reinforcement alone, the tensile stress shall
be not greater than the values given below:
72
NATIONAL BUILDING CODE OF INDIA
Grade
of
Concrete
Tensile
Stress,
N/mm 2
1.2 2.0 2.8 3.2 3.6 4.0 4.4 4.8 5.2 5.6
The tensile stress shall be calculated as
where
A, + m At
F t - Total tension on the member minus pretension
in steel, if any, before concreting;
A e - Cross-sectional area of concrete excluding
any finishing material and reinforcing steel;
m = Modular ratio; and
A st - Cross-sectional area of reinforcing steel in
tension.
B-2.1.2 Bond Stress for Deformed Bars
In the case of deformed bars conforming to accepted
standard [6-5A(40)], the bond stresses given in
Table 21 may be increased by 60 percent.
Table 21 Permissible Stresses in Concrete
(Clauses B-1.3, B-2.1, B-2.1.2, B-2.3 and B-4.2)
Grade of
Permissible Stress in
Permissible Stress in
Concrete
Compression
Bond (Average) for
^A^
Plain Bars in Tension
Bending
-N
Direct
CT c b c
CTcc
1m
(1)
(2)
(3)
(4)
M10
3.0
2.5
M15
5.0
4.0
0.6
M20
7.0
5.0
0.8
M25
8.5
6.0
0.9
M30
10.0
8.0
1.0
M35
11.5
9.0
1.1
M40
13.0
10.0
1.2
M45
14.5
11.0
1.3
M50
16.0
12.0
1.4
M55
17.5
13.0
1.5
NOTES
1 The values of permissible shear stress in concrete are given in
Table 23.
2 The bond stress given in
col 4 shall be increased by 25 percent
for bars in <
:ompression.
B-2.2 Permissible Stresses in Steel Reinforcement
Permissible stresses in steel reinforcement shall not
exceed the values specified in Table 22.
B-2.2.1 In flexural member the value of <r st given in
Table 22 is applicable at the centroid of the tensile
reinforcement subject to the condition that when more
than one layer of tensile reinforcement is provided,
the stress at the centroid of the outermost layer shall
not exceed by more than 10 percent the value given in
Table 22.
B-2.3 Increase in Permissible Stresses
Where stresses due to wind (or earthquake) temperature
and shrinkage effects are combined with those due to
dead, live and impact load, the stresses specified in
Tables 21, 22 and 23 may be exceeded up to a limit of
33>3 percent. Wind and seismic forces need not be
considered as acting simultaneously.
B-3 PERMISSIBLE LOADS IN COMPRESSION
MEMBERS
B-3.1 Pedestals and Short Columns with Lateral
Ties
The axial load P permissible on a pedestal or short
column reinforced with longitudinal bars and lateral
ties shall not exceed that given by the following
equation:
^OcA + OsAc
where
a = Permissible stress in concrete in direct
cc
compression,
A c = Cross-sectional area of concrete excluding
any finishing material and reinforcing steel,
A sc = Cross-sectional area of the longitudinal steel.
NOTE — The minimum eccentricity mentioned
in 24.4 may be deemed to be incorporated in the above
equation.
B-3.2 Short Columns with Helical Reinforcement
The permissible load for columns with helical
reinforcement satisfying the requirement of 38.4.1
shall be 1.05 times the permissible load for similar
member with lateral ties or rings.
B-3.3 Long Columns
The maximum permissible stress in a reinforced
concrete column or part thereof having a ratio of
effective column length to least lateral dimension
above 12 shall not exceed that which results from the
multiplication of the appropriate maximum permissible
stress as specified under B-2.1 and B-2.2 by the
coefficient C T given by the following formula:
C=L25-
L
48 fc
where
C = Reduction coefficient;
r
Z ef = Effective length of column; and
b - Least lateral dimension of column; for
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
73
Table 22 Permissible Stresses in Steel Reinforcement
(Clauses B-2.2, B-2.2.1, B-2.3 andB-42)
SI
No.
0)
Type of Stress in Steel Reinforcement
Permissible Stresses in N/mm
Mild Steel Bars Medium Tensile High Yield Strength
(2)
Grade 1 of
IS 432 (Part 1)
(3)
IS 432 (Part 1) Conforming to IS 1786
(4)
(Grade Fe 415)
(5)
i) Tension (o st or a sv )
a) U n to and i.nc!udin° 20 i
b) Over 20 mm
ii) Compression in column bars (a sc )
iii) Compression in bars in a beam or slab when the
compressive resistance of the concrete is taken into
account
iv) Compression in bars in a beam or slab where the
compressive resistance of the concrete is not taken into
account:
a) Up. to and including 20 mm
b) Over 20 mm
140 Half the guaranteed 230
130 yield stress subject to 230
a maximum of 190
130 130 190
The calculated compressive stress in the surrounding concrete
multiplied by 1 .5 times the modular ratio or o sc whichever is lower
1 40 Half the guaranteed 1 90
130 yield stress subject to 190
a maximum of 190
NOTES
1 For high yield strength deformed bars of Grade Fe 500 the permissible stress in direct tension and flexural tension shall be 0.55/ .
The permissible stresses for shear and compression reinforcement shall be as for Grade Fe 415.
2 For welded wire fabric confoniiin** to acce n ted standard ^6-5A^46^ the permissible value in tension o is 230 M/ mm 2 ,
3 For the purpose of this Section, the yield stress of steels for which there is no clearly defined yield point should be taken to be 0.2
percent proof stress.
4 When mild steel conforming to Grade II of accepted standard [6-5A(45)] is used, the permissible stresses shall be 90 percent of the
permissible stresses in col 3, or if the design details have already been worked out on the basis of mild steel conforming to Grade 1 of
accepted standard [6-5A(45)]; the area of reinforcement shall be increased by 10 percent of that required for Grade 1 steel.
column with helical reinforcement, b is the
diameter of the core.
For more exact calculations, the maximum permissible
stresses in a reinforced concrete column or part thereof
having a ratio of effective column length to least lateral
radius of gyration above 40 shall not exceed those
which result from the multiplication of the appropriate
maximum permissible stresses specified under B-2=l
and B-2.2 by the coefficient C. given by the following
formula:
where
C = 1.25-
L
160 i
where * min is the least radium of gyration.
B-3.4 Composite Columns
a) Allowable load — The allowable axial load
P on a composite column consisting of
structural steel or cast-iron column thoroughly
encased in concrete reinforced with both
longitudinal and spiral reinforcement, shall
not exceed that given by the following
formula:
P = a A +a A +a A
a = Permissible stress in concrete in direct
cc
compression;
A c = Net area of concrete section; which is equal
to the gross area of the concrete section
-A -A ;
sc m
A sc = Cross-sectional area of longitudinal bar
reiiiiOi cement;
a = Allowable unit stress in metal core, not
mc
to exceed 125 N/mm 2 for a steel core, or
70 N/mm 2 for a steel core, or 70 N/mm 2 for
a cast iron core; and
A = Cross-sectional area of the steel or cast iron
m
core,
b) Metal core and reinforcement — The cross-
sectional area of the metal core shall not
c±vr>Pn*A OH ■ne*rr>ar\t r\£ tV\a ctrr\oo arao r\£ f h «
V/WVVU ^*\J UV1VV11L V^± HJV tlUOO U.J.V'U V^i. LllV
column. If a hollow metal core is used, it shall
be filled with concrete. The amount of
longitudinal and spiral reinforcement and the
requirements as to spacing of bars, details
of splices and thickness of protective
shall outside the spiral, shall conform to
requirements of 25.5.3. A clearance of at least
74
NATIONAL BUILDING CODE OF INDIA
75 mm shall be maintained between the spiral
and the metal core at all points, except that
when the core consists of a structural steel
H-column, the minimum clearance may be
reduced to 50 mm,
c) Splices and connections of metal cores —
Metal cores in composite columns shall be
accurately milled at splices and positive
provisions shall be made for alignment of one
core above another. At the column base,
provisions shall be make to transfer the load
to the footing at safe unit stresses in
accordance with 33. The base of the metal
section shall be designed to transfer the load
from the entire composite columns to the
footing, or it may be designed to transfer the
load from the metal section only, provided it
is placed in the pier or pedestal as to leave
ample section of concrete above the base for
the transfer of load from the reinforced
concrete section of the column by means of
bond on the vertical reinforcement and by
direct compression on the concrete. Transfer
of loads to the metal core shall be provided
for by the use of bearing members, such as
billets, brackets or other positive connections,
these shall be provided at the top of the metal
core and at intermediate floor levels where
required. The column as a whole shall satisfy
the requirements of formula given under (a)
at any point; in addition to this, the reinforced
concrete portion shall be designed to carry,
according to B-3.1 or B-3.2 as the case
may be, all floor loads brought into the
column at levels between the metal brackets
or connections. In applying the formula
under B-3.1 or B-3.2 the gross area of column
shall be taken to be the area of the concrete
section outside the metal core, and the
allowable load on the reinforced concrete
section shall be further limited to 0.28/ ck times
gross sectional area of the column.
d) Allowable load on metal core only — The
metal core of composite columns shall be
designed to carry safely any construction or
other loads to be placed upon them prior to
their encasement in concrete.
B-4 MEMBERS SUBJECTED TO COMBINED
AXIAL LOAD AND BENDING
B-4.1 Design Based on Uncracked Section
A member subjected to axial load and bending (due to
eccentricity of load, monolithic construction, lateral
forces, etc) shall be considered safe provided the
following conditions are satisfied.
a)
-<1
where
o = Calculated direct compressive stress in
concrete,
o = Permissible axial compressive stress in
concrete,
°cbc cai = Calculated bending compressive stress in
concrete, and
o cbc = Permissible bending compressive stress
in concrete.
b) The resultant tension in concrete is not greater
than 35 percent and 25 percent of the resultant
compression for biaxial and uniaxial bending
respectively, or does not exceed three-fourths,
the 7 day modulus of rupture of concrete.
NOTES
1 o A
■ for columns with ties where
cbc,ca! 4+ i.5 m ^
P, A c and A sc defined in B-3.1 and m is the modular
ratio.
M
2 ^cbccai ~~^~ where M equals the moment and Z equals
modulus of section. In the case of sections subject to
moments in two directions, the stress shall be calculated
separately and added algebraically.
B-4.2 Design Based on Cracked Section
If the requirements specified in B-4.1 are not satisfied,
the stresses in concrete and steel shall be calculated by
the theory of cracked section in which the tensile
resistance of concrete is ignored. If the calculated
stresses are within the permissible stress specified in
Tables 21, 22 and 23 the section may be assumed to
be safe.
NOTE — The maximum stress in concrete and steel may be
found from tables and charts based on the cracked section
theory or directly by determining the no-stress line which
should satisfy the following requirements:
a) The direct load should be equal to the algebraic sum of
the forces on concrete and steel,
b) The moment of the external loads about any reference
line should be equal to the algebraic sum of
the moment of the forces in concrete (ignoring the
tensile force in concrete) and steel about the same
line, and
c) The moment of the external loads about any
other reference lines should be equal to the algebraic
sum of the moment of the forces in concrete (ignoring
the tensile force in concrete) and steel about the
same line.
B-4.3 Members Subjected to Combined Direct
Load and Flexure
Members subjected to combined direct load flexure
and shall be designed by limit state method as given
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
75
in 38.5 after applying appropriate load factors as given
in Table 18.
B-5 SHEAR
B-5.1 Nominal Shear Stress
The nominal shear stress T v in beams or slabs of
uniform depth shall be calculated by the following
equation:
V
T =
bd
where
V = Shear force due to design loads,
b = Breadth of the member, which for flanged
sections shall be taken as the breadth of the
web, and
d = Effective depth.
B-5.1, 1 Beams of Varying Depth
In the case of beams of varying depth, the equation
shall be modified as:
Mtan/?
T = " d
bd
where
x , V, b and d are the same as in B-5.1.
M = Bending moment at the section, and
P - Angle between the top and the bottom edges
of the beam.
The negative sign in the formula applies when the
bending moment M increases numerically in the same
direction as the effective depth d increases, and the
positive sign when the moment decreases numerically
in this direction.
B-5.2 Design Shear Strength of Concrete
B-5.2.1 The permissible shear stress in concrete in
beams without shear reinforcement is given in
Table 23.
B-5.2.1.1 For solid slabs the permissible shear stress
in concrete shall be kz c where k has the value given
below:
Overall 300 275 250 225 200 175 150
Depth of or or
Slab, mm more less
k 1.00 1.05 1.10 1.15 1.20 1.25 1.30
NOTE — This does not apply to flat slabs for which 30.6 shall
apply.
B-5.2.2 Shear Strength of Members Under Axial
Compression
For members subjected to axial compression P, the
permissible shear stress in concrete ^ c given in
Table 23, shall be multiplied by the following factor:
3=1 +
5P
but not exceeding 1.5.
Table 23 Permissible Shear Stress in Concrete
{Clauses B-2.1, B-2.3, B-4.2, B-5.2.1, B-5.2.2, B-5.3, B-5.4, B-5.5.3, B-6.3.2,
B-6.3.3 and B-6.4.3)
100 M
Permissible Shear Stress in
Concrete Tc N/mm 2
Grade of Concrete
M15
M20
M25
M30
M35
M 40 and above
(1)
(2)
(3)
(4)
(5)
(6)
(7)
<0.15
0.18
0.18
0.19
0.20
0.20
0.20
0.25
0.22
0.22
0.23
0,23
0.23
0.23
0.50
0.29
0.30
0.31
0.31
0.31
0.32
0.75
0.34
0.35
0.36
0.37
.*- 0.37
0.38
1.00
0.37
0.39
0.40
0.41
0.42
0.42
1.25
0.40
0.42
0.44
0.45
0.45
0.46
1.50
0.42
0.45
0.46
0.48
0.49
0.49
1.75
0.44
0.47
0.49
0.50
0.52
0.52
2.00
0.44
0.49
0.51
0.53
0.54
0.55
2.25
0.44
0.51
0.53
0.55
0.56
0.57
2.50
0.44
0.51
0.55
0.57
0.58
0.60
2.75
0.44
0.51
0.56
0.58
0.60
0.62
3.00
0.44
0.51
0.57
0.60
0.62
0.63
and above
NOTE — A s is that area of longitudinal tension reinforcement which continues at least one effective depth beyond the section being
considered except at supports where the full area of tension reinforcement may be used provided the detailing conforms to 25.2*2
and 25.2.3.
76
NATIONAL BUILDING CODE OF INDIA
where
where
P = Axial compressive force in N,
A = Gross area of the concrete section in mm 2 ,
E
/ ck = Characteristic compressive strength of
concrete.
B-5.2.3 With Shear Reinforcement
When shear reinforcement is provided the nominal
shear stress T, in beams shall not exceed x c max given in
Table 24.
B-5.2.3.1 For slabs, t v shall not exceed half the value
of T given in Table 24.
c max &
TabJe 24 Maximum Shear Stress t muw N/mm 2
c max
(Clauses B-5.2.3, B-5.2.3.1, B-5.5.1 andB-63.1)
Concrete
M15
M20
M25
M30
M35
M 40 and
Grade
above
T c max N/mm 2
1.6
1.8
1.9
2.2
2.3
2.5
B-5.3 Minimum Shear Reinforcement
When x v is less than T c given in Table 23, minimum
shear reinforcement shall be provided in accordance
with 25.5.1.6.
B-5.4 Design of Shear Reinfocement
When x v exceeds x c given in Table 23, shear
reinforcement shall be provided in any of the following
forms:
a) Vertical stirrups,
b) Bent-up bars along with stirrups, and
c) Inclined stirrups.
Where bent-up bars are provided, their contribution
towards shear resistance shall not be more than half
that of the total shear reinforcement.
Shear reinforcement shall be provided to carry a shear
equal to V- % c bd. The strength of shear reinforcement
V shall be calculated as below:
s
a) For vertical stirrups
S
b) For inclined stirrups or a series of bars bent-
up at different cross-sections:
^ _ sv^sv ( gm a + cog a ^
c) For single bar or single group of parallel bars,
all bent-up at the same cross-section:
A sv = Total cross-sectional area of stirrup legs or
bent-up bars within a distance,
5 v = Spacing of the stirrups or bent-up bars along
the length of the member,
x. = Design shear strength of the concrete,
b = Breadth of the member which for flanged
beams, shall be taken as the breadth of the
web b w ,
o = Permissible tensile stress in shear
sv
reinforcement which shall not be taken
greater than 230 N/mm 2 ,
a = Angle between the inclined stirrup or bent-
up bar and the axis of the member, not less
than 45°, and
d - Effective depth.
NOTE — Where more than one type of shear reinforcement is
used to reinforce the same portion of the beam, the total shear
resistance shall be computed as the sum of the resistance for
the various types separately. The area of the stirrups shall not
be less than the minimum specified in 25.5.1.6.
B-5.5 Enhanced Shear Strength of Sections Close
to Supports
B-5.5.1 General
Shear failure at sections of beams and centilevers
without shear reinforcement will normally occur on
plane inclined at an angle 30° to the horizontal. If the
angle of failure plane is forced to be inclined more
steeply than this [because the section considered
(X -X) in Fig. 24 is close to a support or for other
reasons], the shear force required to produce failure is
increased.
The enhancement of shear strength may be taken into
account in the design of sections near a support by
increasing design shear strength of concrete, x c to Id
t c /g v provided that the design shear stress at the face
of support remains less than the values given in
Table 24. Account may be taken of the enhancement
in any situation where the section considered is closer
to the face of a support of concentrated load than twice
the effective depth, d. To be effective, tension
reinforcement should extend on each side of the point
where it is intersected by a possible failure plane for a
distance at least equal to the effective depth, or be
provided with an equivalent anchorage.
B-5.5.2 Shear Reinforcement for Sections Close to
Supports
If shear reinforcement is required, the total area of this
is given by:
A s = a v b (x v - 2d T c /a v )/a sv > 0.4 a w b/0.87f y
This reinforcement should be provided within the
PART 6 STRUCTURAL DESIGN — SECTION 5 CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
77
middle three quarters of a y . Where a v is less than d,
horizontal shear reinforcement will be more effective
than vertical.
B-5.5.3 Enhanced Shear Strength Near Supports
(Simplified Approach)
The procedure given in B-5.5.1 and B-5.5.2 may be
used for all beams. However for beams carrying
generally uniform load or where the principal load is
located further than 2 d from the face of support, the
shear stress may be calculated at a section a distance d
from the face of support. The value of T c is calculated
in accordance with Table 23 and appropriate
shear reinforcement is provided at sections closer to
the support, no further check for such section is
required.
B-6 TORSION
B-6.1 General
In structures where torsion is required to maintain
equilibrium, members shall be designed for torsion in
accordance with B-6.2 to B-6.4. However, for such
indeterminate structures where torsion can be
eliminated by releasing redundant restraints, no specific
design for torsion is necessary provided torsional
stiffness is neglected in the calculation of internal
forces. Adequate control of any torsional, cracking is
provided by the shear reinforcement as per B-5.
NOTE — The approach to design in this clause for torsion is
as follows;
Torsional reinforcement is not calculated separately from that
required for bending and shear. Instead the total longitudinal
reinforcement is determined for a fictitious bending moment
which is a function of actual bending moment and torsion;
similarly web reinforcement is determined for a fictitious shear
which is a function of actual shear and torsion,
B-6.1.1 The design rules laid down in B-6.3 and B-6.4
shall apply to beams of solid rectangular cross-section.
However, these clauses may also be applied to flanged
beams by substituting b for b, in which case they are
generally conservative; therefore specialist literature
may be referred to.
B-6.2 Critical Section
Sections located less than a distance d, from the face
of the support may be designed for the same torsion as
computed at a distance d, where d is the effective depth.
B-6.3 Shear and Torison
B-6.3.1 Equivalent Shear
Equivalent shear, V e shall be calculated from the
formula:
V ■ =V + 1.6?
where
V = Equivalent shear,
V = Shear
T = Torsional moment, and
b - Breadth of beam.
The equivalent nominal shear stress, x ve , in this case
shall be calculated as given in B-5.1, except for
substituting V by V . The values of T ve shall not exceed
the values of x given in Table 24.
c max ^
B-6.3. 2 If the equivalent nominal shear stress l ve does
not exceed x , given in Table 23, minimum shear
reinforcement shall be provided as specified
in 25.5.1.6.
B-6.3.3 If x exceeds x c given in Table 23, both
longitudinal and transverse reinforcement shall be
provided in accordance with B-6.4.
B-6.4 Reinforcement in Members Subjected to
Torsion
B-6.4.1 Reinforcement for torsion, when required,
shall consist of longitudinal and transverse
reinforcement.
B-6.4.2 Longitudinal Reinforcement
The longitudinal reinforcement shall be designed to
resist an equivalent bending moment, M el , given by
where
M = Bending moment at the cross-section, and
(1 + D/fc)
M= T-
1.7
-, where T is the torsional
moment, D is the overall depth of the beam
and b is the breadth of the beam.
B-6.4.2.1 If the numerical value of M t as defined
in B-6.4.2 exceeds the numerical value of the moment
M, longitudinal reinforcement shall be provided on the
flexural compression face, such that the beam can also
withstand an equivalent moment M e2 given by M e2 =
M - M, the moment M e2 being taken as acting in the
opposite sense to the moment M.
B-6.4.3 Transverse Reinforcement
Two legged closed hoops enclosing the corner
longitudinal bars shall have an area of cross-section
A given by
r.s w + v.s v
"» b l d l S„ 2.54<r sv '
reinforcement shall not be less than
but the total transverse
78
NATIONAL BUILDING CODE OF INDIA
(*™Oi.j,
where
T = Torsional moment,
V = Shear force,
S v = Spacing of the stirrup reinforcement,
b x - Centre-to-centre distance between corner
bars in the direction of the depth,
d l = Centre-to centre distance between corner
bars in the direction of the depth,
b = Breadth of the member
a = Permissible tensile stress in shear
sv
reinforcement
t ve = Equivalent shear stress as specified
in B-6.3.1, and
x c = Shear strength of the concrete as specified
in Table 23.
ANNEX C
(Clauses 21.3.2, 22.2.1 and 41 A)
CALCULATION OF DEFLECTION
C-l TOTAL DEFLECTION
C-l.l The total deflection shall be taken as the sum
of the short-term deflection determined in accordance
with C-2 and the long-term deflection, in accordance
with C-3 and C-4.
C-2 SHORT-TERM DEFLECTION
C-2,1 The short-term deflection may be calculated by
the usual methods for elastic deflections using the
short-term modulus of elasticity of concrete, E c and
an effective moment of intertia / eff given by the
following equation:
;but
—
1.2^
M
1
(
X
~d
)t
^'eff^
where
/ = Moment of inertia of the cracked section,
A/ = Cracking moment, equal to
J cr Ei
y t
where
^ r = Modulus of rupture of concrete,
/ = Moment of inertia of the gross section
about the centroidal axis, neglecting the
reinforcement, and y t is the distance from
centroidal axis of gross section, neglecting
the reinforcement, to extreme fibre in
tension,
M = Maximum moment under service loads
z ^ Lever arm,
x = Depth of neutral axis,
d - Effective depth,
6 w = Breadth of web, and
b ~ Breadth of compression face.
For continuous beams, deflection shall be
calculated using the values of / , / and M
© gr' gr r
modified by the following equation:
~X 1 +X 2
*e=*i
+ (1-* 1 )X
where
X = Modified value of X,
e '
X v X 2 = Values of X at the supports,
X o = Value of X at mid span,
k { = Coefficient given in Table 25, and
X = Value of / , / or M r as appropriate.
C-3 DEFLECTION DUE TO SHRINKAGE
C-3.1 The deflection due to shrinkage a cs may be
computed from the following equation:
a = Lw / 2
cs 3 "cs
where
k 3 is a constant depending upon the support
conditions,
0.5 for cantilevers,
0.125 for simply supported members,
0.086 for members continuous at one end, and
0.063 for fully continuous members,
£
\|/ cs is shrinkage curvature equal to k 4 - SL
where e cs is the ultimate shrinkage strain of
concrete (see 5.2.4),
k 4 =0.72x^—5- <1.0for 0.25 < P t -P. <1.0
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
79
: o.65x-^=J- <, 1.0 for 0.25 < P - P > 1.0
where
Table 25 Values of Coefficient, k x
(Clause C-2.1)
h 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4
or
less
/:, 0.03 0.08 0.16 0.30 0.50 0.73 0.91 0.97 1.0
NOTE — k 2 is given by
k _ M, + M 2
2 M m + M^
where
M V M 2 = Support moments, and
and D is the total depth of the section, and / is the
length of span.
C-4 DEFLECTION DUE TO CREEP
C-4.1 The creep deflection due to permanent
loads a may be obtained from the following
equation:
Q , , ~ CI- , , — CI- ,
cc (perm) i, cc (perm) 1 (perm)
where
a icc(perm) = Initial plus creep deflection due to
permanent loads obtained using an
elastic analysis with an effective
modulus of elasticity;
E ce = — £ -, 9 being the creep coefficient;
and
a t , = Short-term deflection due to permanent
i (perm) r
load using £\
ANNEX D
{Clauses 23.4 and 36.1.2)
SLABS SPANNING IN TWO DIRECTIONS
D-l RESTRAINED SLABS
D-1.0 When the corners of a slab are prevented from
lifting, the slab may be designed as specified in D-l.l
to D-1.11.
D-l.l The maximum bending moments per unit width
in a slab are given by the following equations:
M„ =awl
M y =a y w/ y
where
a x and a are coefficients given in Table 26,
w - Total design and load per unit area.
M , M - Moments on strips of unit width
spanning / x and / respectively, and
l x and / = Lengths of the shorter span and longer
span respectively.
D-1.2 Slabs are considered as divided in each direction
into middle strips and edge strips as shown in Fig. 25
the middle strip being three-quarters of the width and
each edge strip one-eight of the width.
D-1.3 The maximum moments calculated as in D-l.l
apply only to the middle strips and no re-distribution
shall be made.
D-1.4 Tension reinforcement provided at mid-span in
the middle strip shall extend in the lower part of the
slab to within 0.25 / of a continuous edge, or 0.15 / of
a discontinuous edge.
D-1.5 Over the continuous edges of a middle strip,
the tension reinforcement shall extend in the upper part
of the slab a distance of 0. 15 / from the support, and at
least 50 percent shall extend a distance of 0.3 /.
D-1.6 At a discontinuous edge, negative moments may
arise. They depend on the clegree of fixity at the edge
of the slab but, in general, tension reinforcement equal
to 50 percent of that provided at mid-span extending
0.1 / into the span will be sufficient.
D-1.7 Reinforcement in edge strip, parallel to that
edge, shall comply with the minimum given in
Section 3 and the requirements for torsion given
in D-1.8 to D-1.10.
D-1.8 Torsion reinforcement shall be provided at any
corner where the slab is simply supported on I5bth edges
meeting at that corner. It shall consist of top and bottom
reinforcement, each with layers of bars placed parallel
80
NATIONAL BUILDING CODE OF INDIA
Table 26 Bending Moment Coefficients for Rectangular Panels Supported on
(Clauses D-l.l and 23.4.1)
Case
Type of Panel
Short Span Coefficients
%
Long Span
No.
and Moments
(Values of l y /l x )
Coefficients Oy for
Considered
All AZnlunc nf
1.0
1.1
1.2
1.3
1.4
1.5
1.75
2.0
yu
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(id
1
Interior Panels:
Negative moment at
0.032
0.037
0.043
0.047
0.051
0.053
0.060
0.065
0.032
continuous edge
Positive moment at
0.024
0.028
0.032
0.036
0.039
0.041
0.045
0.049
0.024
mid-span
2
One Short Edge
Discontinuous:
Negative moment at
0.037
0.043
0.048
0.051
0.055
0.057
0.064
0.068
0.037
continuous edge
Positive moment at
0.028
0.032
0.036
0.039
0.041
0.044
0.048
0.052
0.028
mid-span
3
One Long Edge
Discontinuous:
Negative moment at
0.037
0.044
0.052
0.057
0.063
0.067
0.077
0.085
0.037
continuous edge
Positive moment at
0.028
0.033
0.039
0.044
0.047
0.051
0.059
0.065
0.028
mid-span
4
Two-Adjacent Edges
Discontinuous:
Negative moment at
0.047
0.053
0.060
0.065
0.071
0.075
0.084
0.091
0.047
continuous edge
Positive moment at
0.035
0.040
0.045
0.049
0.053
0.056
0.063
0.069
0.035
mid-span
5
Two Short Edges
Discontinuous:
Negative moment at
0.045
0.049
0.052
0.056
0.059
0.060
0.065
0.069
—
wuuiiuuuj ^"ex-
positive moment at
0.035
0.037
0.040
0.043
0.044
0.045
0.049
0.052
0.035
mid-span
6
Two Long Edges
Discontinuous:
Negative moment at
—
—
—
—
—
—
—
—
0.045
continuous edge
Positive moment at
0.035
0.043
0.051
0.057
0.063
0.068
0.080
0.088
0.035
mid-span
7
Three Edges
Discontinuous:
(One Long Edge
Continuous)
Negative moment at
0.057
0.064
0.071
0.076
0.080
0.084
0.091
0.097
—
continuous edge
Positive moment at
0.043
0.048
0.053
0.057
0.060
0.064
0.069
0.073
0.043
mid-span
8
Three Edges
Discontinuous
(One Short Edge
Continuous):
Negative moment at
—
—
—
—
—
—
—
—
0.057
continuous edge
Positive moment at
0.043
0.051
0.059
0.065
0.071
0.076
0.087
0.096
0.043
mid-span
9
Four Edges
Discontinuous:
Positive moment at
0.056
0.064
0.072
0.079
0.085
0.089
0.100
0.107
0.056
mid-span
PART 6 STRUCTURAL DESIGN — SECTION 5 CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
81
Ix
UJ 0.
i
-ly-
MIDDLE STRIP
-9 lv
ilu a.
IQ l=
'LU (7)
— ly — »-
Ix
P
n
Ix
EDGE STRIP
MIDDLE STRIP
t .1
i i
EDGE STRIP ^
8
25 A - FOR SPAN Ix
25 B - FOR SPAN ly
Fig. 25 Division of Slab into Middle and Edge Strips
to the sides of the slab and extending from the edges a
minimum distance of one-fifth of the shorter span. The
ai^a ui i^iiuwiv^^uiA^iii in ^civ^ii u± liivoi*- iuui lajr^ia anaii
he three-rmarters of the area renuired for the maximum
— _ ± _ _ — ± —
mid-span moment in the slab.
D-L9 Torsion reinforcement equal to half that
described in D-1.8 shall be provided at a corner
contained by edges over only one of which the slab is
continuous.
D-1.10 Torsion reinforcements need not be provided
at any corner contained by edges over both of which
the slab is continuous.
D-l.ll Where / // is greater than 2, the slabs shall be
designed as spanning one way.
D-2 SIMPLY SUPPORTED SLABS
T^-'J 1 \X/T-t£»-n cimnh; cnnnrtftpH oIqV^c Ha -nr\t ViqvP 1
Jf _ ,*.»-m. TT JLJLWJLX LJlllljJljr uu^pvfi IVV1 D1UI/U) v* vy 11UI HUT v
adequate provision to resist torsion at corners and to
prevent the corners from lifting, the maximum
,m 6
enuation:
"i —
^=V(
M y =a y wi 2 x
where
M Y , M v , / v , / v are same as those in D-l.l, and
a x and a are moment coefficients given in
Table 27/
D-2. 1.1 At least 50 percent of the tension
reinforcement provided at mid-span should extend
to the supports. The remaining 50 percent should
f\ 1 7 ~f *U„ r,,,„„~*.* n „
ui \j. 1 i ui tut; aujjpuit, as
m^Li- t\m Tfc !• -%.m a. r*\ mux. ~: ,*.„ j* ci-L- o : •__ ti t^« j.1 ~*
lauie j*i oenuuig iviuiiiem ^uemcienis lur oiaus spanning in xwu uirecuuiis ai
Sf1„ T^V
1 \
/x//y
1.0
1.1
1.2
1.3
1.4
1.5
1.75
2.0
2.5
3.0
CCx
0.062
0.074
0.084
0.093
0.099
0.104
0.113
0.118
0.122
0.124
a y
0.062
0.061
0.059
0.055
0.051
0.046
0.037
0.029
0.020
0.014
82
NATIONAL BUILDING CODE OF INDIA
ANNEX E
(Clause 25.2)
EFFECTIVE LEGNTH OF COLUMNS
E-l In the absence of more exact analysis, the effective
length of columns in framed structures may be obtained
from the ratio of effective length to unsupported length
IJl give in Fig. 26 when relative displacement of the
ends of the column is prevented and in Fig. 26 when
relative lateral displacement of the ends is not
prevented. In the latter case, it is recommended that
the effective length ratio IJl may not be taken to be
less than 1.2.
NOTES
1 Figures 26 and 27 are reproduced from 'The Strutural
Engineer' No. 1, Volume 52, July 1974 by the permission of
the Council of the Institution of Structural Engineers, U.K.
2 In Fig. 26 and 27 fi x and/^ are equal to
K-+K h
where the summation is to be done for the members framing
into a joint at top and bottom respectively; and K c and K h being
the flexural stiffness for column and beam respectively.
E-2 To determine whether a column is a no sway or a
sway column, stability index Q may be computed as
given below:
where
Q =
PA
u u
Hh
Sum of axial loads on all column in the
storey,
HINGED 1.0
0.9
v<
FIXED
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
o
"s^
N %
\ c
N.
V
o
^vv
x °-
So
XA Ox X
X % X
) >
>v q
\^\i
\%
^
N
\*«
& \
v I
v
V
V
V|
o^
\
\.
0\ 0.1 0.
2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
FIXED P2 HINGED
Fig. 26 Effective Length Ratios for a Column in a Frame with no Sway
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
83
HINGED 1.0
0.9
0.8
0.7
0.6
Pi
0.5
0.4
0.3
0.2
0.1
FIXED
v<4
"NX*
V
k *N
>w 7
\ "°\
. 7 ^
N$?
N/>?
\
\\
Sw '„
V \
\\
\
c 1
\ \7
.
\
\
\
\\
\
L O
\
\
\
\\
FIXED
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
02
HINGED
Fig. 27 Effective Length Ratios for a Column in a Frame
Without Restraint Against Sway
A u = Elastically computed first order lateral
deflection,
H a = Total lateral force acting within the storey,
and
h = Height of the storey.
If Q < 0.04, then the column in the frame may be taken
as no sway column, otherwise the column will be
considered as sway column.
E-3 For normal usage assuming idealized conditions,
the effective length Z ef of in a given plane may be
assessed on the basis of Table 28.
84
NATIONAL BUILDING CODE OF INDIA
Table 28 Effective Length of Compression Members
(Clause E-3)
*-?*,£! *^v- urn uiiu i\i/3iiaiui, vi
Compression Members
(1)
(2)
Effective Length
(3)
Effective Length
(4)
crrectiveiy neia in position and
restrained against rotation at
both ends
mm
0.50/
0.65/
Effectively held in position at
both ends, restrained against
rotation at one end
^
wmw/M
0.70 /
0.80/
Effectively held in position at
both ends, but not restrained
against rotation
^
1.00/
L00/
Effective!*' held in "osition and
restrained against rotation at one
end, and at the other restrained
against rotation but not held in
position
I
/
/
r
W/////////S
1.00/
1.20/
Effectively held in position and
restrained against rotation in one
end, and at the other partially
restrained against rotation but
not heid in position
<^>
/
/
f
W////////Z/
1.50/
Effectively held in position at
one end but not restrained
against rotation, and at the other
end restrained against rotation
but not held in position
D
mmm
2.00/
2.00/
Effectively held in position and
restrained against rotation at one
end but not held in position nor
restrained against rotation at the
other end
W//MM
NOTE — / is the unsupported length of compression member.
2.00/
2.00/
PART 6 STRUCTURAL DESIGN — SECTION 5 CONCRETE: 5A PL AIN AND REINFORCED CONCRETE
85
ANNEX F
(Clauses 34.3.2 and 42.1)
CALCULATION OF CRACK WIDTH
Provided that the strain in the tension reinforcement is
limited to 0.8 F /E s , the design surface crack width,
which should not exceed the appropriate value given
in 34.3.2 may be calculated from the following
equation:
Design surface crack width
3a„£ m
W =-
2{a a -C^)
1 +
where
a cr = Distance from the point considered to the
surface of the nearest longitudinal bar,
C min - Minimum cover to the longitudinal bar,
€ m = Average steel strain at the level considered,
h = Overall depth of the member, and
x = Depth of the neutral axis.
The average steel strain £ m may be calculated on the
basis of the following assumption:
The concrete and the steel are both considered to be
fully elastic in tension and in compression. The elastic
modulus of the steel may be taken as 200 kN/mm 2 and
the elastic modulus of the concrete is as derived from
the equation given in 5.2.3.1 both in compression and
in tension.
Alternatively, as an approximation, it will normally
be satisfactory to calculate the steel stress on the basis
of a cracked section and then reduce this by an amount
equal to the tensile force generated by the triangular
distributions, having a value of zero at the neutral axis
and a value at the centroid of the tension steel of
1 N/mm 2 instantaneously, reducing to 0.55 N/mm 2 in
the long-term, acting over the tension zone divided by
the steel area.
These assumptions are illustrated in Fig. 28,
where
h = Overall depth of the section,
x = Depth from the compression face to the
neutral axis.
f c = Maximum compressive stress in the concrete,
/ = Tensile stress in the reinforcement, and
E s = Modulus of elasticity of the reinforcement.
For a rectangular tension zone, this gives
where
A
s
b
£ m =£,
b(h-x)(a- x)
' 3E.4W-*)
= Area of tension reinforcement,
= Width of the section at the centroid of the
tension steel,
= Strain at the level considered, calculated
ignoring the stiffening of the concrete in the
tension zone,
= Distance from the compression face to the
point at which the crack width is being
calculated, and
- Effective depth.
fs/Ec
fc
X
/
y/^fS/ES
fs
STRESS IN CONCRETE
1 N/mm 2 IN SHORT TERM
0.55 N/mm 2 in LONG TERM
SECTION CRACKED
STRAIN
STRESS
Fig. 28
86
NATIONAL BUILDING CODE OF INDIA
ANNEX G
(Clause 3%.l)
MOMENTS OF RESISTANCE FOR RECTANGULAR AND T-SECTIONS
G-0 The moments of resistance of rectangular and
T-sections based on the assumption of 37.1 are given
in this Annex.
G-l RECTANGULAR SECTIONS
G-l.l Sections Without Compression Reinforcement
The moment of resistance of rectangular sections
without compression reinforcement should be obtained
as follows:
a) Determine the depth of neutral axis from the
following equation:
^ 0.87/ y 4
d 0.36 / ck b.d
b) If the value of xjd is less than the limiting
value (see Note below 37.1), calculate the
moment of resistance by the following
expression:
M u =0.87/ y V*
1-
bdf*
c) If the value of xjd is equal to the limiting
value, the moment of resistance of the section
is given by the following expression:
Mu,Hn,=0.36-
1-0.42-
bd U
d) If xjd is greater than the limiting value, the
section should be redesigned.
In the above equations,
= Depth of neutral axis,
= Effective depth,
= Characteristic strength of reinforcement,
= Area of tension reinforcement,
= Characteristic compressive strength of
concrete,
- Width of the compression face,
^ = Limiting moment of resistance of a section
without compression reinforcement, and
x = Limiting value of x from 37.1.
u, max ° u
G-1.2 Section with Compression Reinforcement
Where the ultimate moment of resistance of section
exceeds the limiting value, M h compression
reinforcement may be obtained from the following
equation:
x
u
d
/v
K
M
K-K™ = f«A*V-<T)
where
M ,M , . d are same as in G-l.l
ir u, hm
f K = Design stress in compression reinforcement
corresponding to a strain of
0.003 5
Ow*')
x = Limiting value of x from 37.1.
ii, max ° u
A^ = Area of compression reinforcement,
and
d' = Depth of compression reinforcement
from compression face.
The total area of tension reinforcement shall be
obtained from the following equation:
Ait = Astl + ^st2
where
A st = Area of the total tensile reinforcement,
A iti - Area of the tensile reinforcement for a singly
reinforced section for M u Um , and
A=A //0.87/.
st2 sc J sc J y
G-2 FLANGED SECTION
G-2.1 For jc u < D r the moment of resistance may be
calculated from the equation given in G-l.l.
G-2.1 The limiting value of the moment of resistance
of the section may be obtained by the following
equation when the ratio D f Id does not exceed 0.2:
Af., =0.36
D
1-0.42-
f*Kd
+ 0.45./ A (* f -fc)D f
2 .
where
M , x ,d and f. are same as in G-l.l,
u' u.max* J ck T
b f = Breadth of the compression face/flange,
b - Breadth of the web,
D f = Thickness of the flange.
G-2.2.1 When the ratio D f Id exceeds 0.2, the moment
of resistance of the section may be calculated by the
following equation:
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
87
M n
where
:036 ^,max
D
1-0.42^=-] / A M 2
+ 0-45/ ct (fc f -6 w )y f [-*-^]
(0.15 x u + 0,65 D f ), but not greater than D f
and the other symbols are same as in G-l.l
and G-2.2.
G-2.3 For jc^ nm > jc u > D f the moment of resistance
may be calculated by the equations given in G-2.2
when D f /x u does not exceed 0.43 and G-2.2.1 when
D f /jc u exceeds 0.43; in both cases substituting jc u max
LIST OF STANDARDS
The following list records those standards which are
acceptable as * good practice' and 'accepted standards'
in the fulfilment of the requirements of the Code. The
standards listed may be used by the Authority as a guide
in conformance with the requirements of the referred
clauses in the Code.
IS No.
(1) 3370
(Part 1) : 1965
(Part 2): 1965
2210 : 1998
3201 : 1988
4090 : 1967
4995
(Part 1) : 1974
(Part 2) : 1974
4998
(Part 1) : 1992
(2) 4845 : 1968
6461
(Part 1) : 1972
(Part 2) : 1972
(Part 3) : 1972
Title
Code of practice for concrete
structures for the storage of
liquid:
General requirements
Reinforced concrete structures
Criteria for design of reinforced
concrete shell structures and
folded plates (first revision)
Criteria for design and
construction of precast-trusses
and purlins (first revision)
Criteria for design of reinforced
concrete arches
Criteria for design of reinforced
concrete bins for Storage
of granular and powdery
materials
General requirements and bin
loads
Design criteria
Criteria for design of reinforced
concrete chimneys: Part 1
Assessment of loads (second
revision)
Definitions and terminology
relating to hydraulic cement
Glossary of terms relating to
cement:
Concrete aggregates
Materials
Concrete reinforcement
IS No.
(Part 4) : 1972
(Part 5): 1972
(Part 6) : 1972
(Part 7) : 1973
(Part 8) : 1973
(Part 9): 1973
(Part 10) : 1973
(Part 11): 1973
(Part 12) : 1973
(3) 269 : 1989
8112: 1989
12269 : 1987
8041 : 1990
455 : 1989
1489
(Part 1) : 1991
(Part 2) : 1991
8043 : 1991
12600 : 1989
12330 : 1988
Title
Types of concrete
Formwork for concrete
Equipment, tool and plant
Mixing, laying, compaction,
curing and other construction
aspect
Properties of concrete
Structural aspects
Tests and testing apparatus
Prestressed concrete
Miscellaneous
Specification for ordinary
Portland cement, 33 grade
(fourth revision)
Specification for 43 grade
ordinary Portland cement (fist
revision)
Specification for 53 grade
ordinary Portland cement
Specification for rapid
hardening Portland cement
(second revision)
Specification for Portland slag
cement (fourth revision)
Specification for Portland
pozzoiana cement:
Fly ash based (third revision)
Calcined clay based (third
revision)
Specification for hydrophobic
Portland cement (second
revision)
Specification for low heat
Portland cement
Specification for sulphate
resisting Portland cement
88
NATIONAL BUILDING CODE OF INDIA
IS No.
(4) 6452 : 1989
6909 : 1990
(5) 3812
(Part 1) : 2003
(Part 2) : 2003
(6) 12089 : 1987
(7) 383 : 1970
(8) 3025
(Part 17) : 1984
(Part 18) : 1984
(Part 22) : 1986
(Part 23) : 1986
(Part 24) : 1986
(Part 32) : 1988
(9) 516:1959
(10)4031
(Part 5) : 1988
(11)9103: 1999
(12) 432
(Part 1) : 1982
1786 : 1985
Title
Specification for high alumina
cement for structural use
Specification for supersulphated
cement
Specification for pulverized
fuel ash;
For use as pozzolana in cement,
cement mortar and concrete
(second revision)
For use as admixture in cement
mortar and concrete (second
revision)
Specification for granulated
slag for manufacture of Portland
slag cement
Specification for coarse and
fine aggregates from natural
sources for concrete (second
revision)
Methods of sampling and test
(physical and chemical) for
water and waste water:
Non-filterable residue (total
suspended solids) (first
revision)
Volatile and fixed residue
(total filterable and non-
filterable) (first revision)
Acidity (first revision)
Alkalinity (first revision)
Sulphates (first revision)
Chloride (first revision)
Method of test for strength of
concrete
Methods of physical tests
for hydraulic cement: Part 5
Determination of initial and
final setting times (first revision)
Specification for admixtures
for concrete (first revision)
Specification for mild steel
and medium tensile steel bars
and hard-drawn steel wire for
concrete reinforcement: Part 1
Mild steel and medium tensile
steel bars (third revision)
Specification for high strength
deformed steel bars and wires
for concrete reinforcement
(third revision)
IS No.
1566 : 1982
2062 : 1999
(13)4082:1996
(14)516:1959
5816 : 1999
(15) 1343 : 1980
(16) 1199: 1959
(17)9013: 1978
(18) 383 : 1970
455 : 1989
(19) 1489
(Part 1) : 1991
(20) 6909 : 1990
(21)4925: 1968
(22) 4926 : 2003
(23) 2386
(Part 3) : 1963
(24) 1791 : 1985
12119: 1987
(25) 14687 : 1999
Title
Specification for hard-drawn
steel wire fabric for concrete
reinforcement (second
revision)
Steel for general structural
purposes (fifth revision)
Recommendations on stacking
and storage of construction
materials and components at
site (second revision)
Method of test for strength of
concrete
Method of test for splitting
tensile strength of concrete
(first revision)
Code of practice for prestressed
concrete (first revision)
Methods of sampling and
analysis of concrete
Method of making, curing
and determining compressive
strength of accelerated cured
concrete test specimens
Specification for coarse and
fine aggregates from natural
sources for concrete (second
revision)
Specification for Portland slag
cement (fourth revision)
Specification for Portland
pozzolana cement: Part 1 Fly
ash based (third revision)
Specification for super-
sulphated cement
Specification for concrete
batching and mixing plant
Code of practice for ready-
mixed concrete (second
revision)
Methods of test for aggregates
for concrete: Part 3 Specific
gravity, density, voids,
absorption and bulking
Specification for batch type
concrete mixers (second
revision)
General requirements for pan
mixers for concrete
Guidelines for falsework for
concrete structure
PART 6 STRUCTURAL DESIGN — SECTIONS CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
89
IS No.
(26)2502: 1963
(27)2751 : 1979
9417 : 1989
(28) 2505 : 1992
2506 : 1985
2514: 1963
4656 : 1968
(29) 11817 : 1986
(30) 7861
(Part 1) : 1975
(Part 2) : 1981
(31)9013: 1978
(32) 13311
(Part 1) : 1992
(Part 2) : 1992
(33) 875
(Part 1) : 1987
(Part 2): 1987
(Part 3) : 1987
(Part 4): 1987
(Part 5) : 1987
Title
Code of practice for bending
and fixing of bars for concrete
reinforcement
Recommended practice for
welding of mild steel plain and
deformed bars for reinforced
construction (first revision)
Recommendations for welding
cold worked bars for reinforced
concrete construction (first
revision)
Concrete vibrators —
Immersion type — General
requirements
General requirements for
screed board concrete vibrators
(first revision)
Specification for concrete
vibrating tables
Specification for form vibrators
for concrete
Classification of joints in
buildings for accommodation of
dimensional deviations during
construction
Code of practice for extreme
weather concreting:
Recommended practice for
hot weather concreting
Recommended practice for
cold weather concreting
Method of making, curing
and determining compressive
strength of accelerated cured
concrete test specimens
Methods of non-destructive
testing of concrete:
Ultrasonic pulse velocity
Rebound hammer
Code of practice for design
loads (other than earthquake)
for buildings and structures:
Dead loads — Unit weights of
building material and stored
materials (secon'd revision)
Imposed loads (second revision)
Wind loads (second revision)
Snow loads (second revision)
Special loads and load
combinations (second revision)
IS No.
(34) 1893
(Part 1) : 2002
(35) 1904 : 1986
(36) 1641 : 1988
(37) 1642 : 1989
(38) 13920:1993
(39)4326: 1993
(40) 1786 : 1985
(41)3414: 1968
(42) 3951
(Part 1) : 1975
(43) 6061
(Part 1) : 1971
(Part 2): 1981
(44) 432
(Part 1) ; 1982
(45) 1566: 1982
Title
Criteria for earthquake resistant
design of structures: General
provisions and buildings (fifth
revision)
Code of practice for design and
construction of foundations in
soils: General requirements
(third revision)
Code of practice for fire safety
of buildings (general): General
principles of fire grading and
classification (first revision)
Code of practice for fire
safety of buildings (general):
Details of construction (first
revision)
Code of practice for ductile
detailing of reinforced concrete
structures subjected to seismic
forces
Code of practice for
earthquake resistant design
and construction of buildings
(second revision)
Specification for high strength
deformed steel bars and wires
for concrete reinforcement
(third revision)
Code of practice for design
and installation of joints in
buildings
Specification for hollow clay
tiles for floors and roofs: Part 1
Filler type (first revision)
Code of practice for
construction of floor and roof
with joists and filler blocks:
With hollow concrete filler
blocks
With hollow clay filler blocks
(first revision)
Specification for mild steel
and medium tensile steel bars
and hard-drawn steel wire for
concrete reinforcement: Part 1
Mild steel and medium tensile
steel bars (third revision)
Specification for hard-
drawn steel wire fabric for
concrete reinforcement (second
revision)
90
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 5 Concrete: 5B Prestressed Concrete
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD ••• 3
1 SCOPE -. 5
2 STRUCTURAL DESIGN USING PRESTRESSED CONCRETE ... 5
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
This sub-section covers the structural design aspects of prestressed concrete.
This sub-section is largely based on IS 1343 : 1980 'Code of practice for prestressed concrete (first revision)*,
which is under revision at the time of publication of this Code. Major changes have been envisaged in the
revision of IS 1343. In the absence of availability of finalized version of revised IS 1343, at the time of revision
of this Code, the provision of design as per existing IS 1343 : 1980 have been continued through appropriate
reference to the same.
PART 6 STRUCTURAL DESIGN — SECTION 5 CONCRETE: 5B PRESTRESSED CONCRETE
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 5 Concrete: 5B Prestressed Concrete
1 SCOPE
This sub-section deals with the general structural use
of prestressed concrete. It covers both work carried
out on site and the manufacture of precast prestressed
concrete units.
2 STRUCTURAL DESIGN USING PRESTRESSED
CONCRETE
The provisions relating to design and general structural
use of prestressed concrete including on;
a) materials, workmanship, inspection and
testing;
b) general design requirements; and
c) structural design: limit state method,
shall be in accordance with good practices contained
in IS 1343 : 1980 'Code of practice for prestressed
concrete (first revision)*.
NOTE — At the time of publication of this sub-section, IS 1 343
was under revision; and once the revised IS 1343 is published,
the same shall replace the provisions given in this sub-section.
PART 6 STRUCTURAL DESIGN — SECTION 5 CONCRETE: 5B PRESTRESSED CONCRETE
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 6 Steel
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 PLANS AND DRAWINGS
4 MATERIALS
5 DESIGN AND CONSTRUCTION IN STEEL
6 DESIGN USING LIMIT STATE METHOD
7 SPACE FRAME
LIST OF STANDARDS
5
5
5
5
5
5
6
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
This Section covers the structural design aspect of steel structures in buildings.
This Section covers the use of hot-rolled structural steel sections and steel tubes in buildings. It permits the
design by working stress method and plastic theory, and now in this revision by limit state method. Further,
reference to space frame has now found place in this Section.
This Section is based on IS 800 : 1984 'Code of practice for general construction in steel (second revision)' and
IS 806 : 1968 'Code of practice for use of steel tubes in general building construction {first revision)', and also
enables design using limit state method.
More rigorous analytical procedures than envisaged as per this Section are available and can be made use of for
finding effective lengths of compression members in determining elastic critical loads.
The Indian Standard IS 800, on which this Section is largely based is under revision at the time of publication of
this Code. Major changes have been envisaged in the revision of IS 800 including introduction of limit state
method. In the absence of availability of finalized version of revised IS 800 at the time of revision of this Section,
in this revision, the provisions of design as per existing IS 800 : 1984 have been continued through appropriate
reference to the same; similarly reference has been made to IS 806. At the same time, the limit state method
having already gained acceptance has been taken into account in this revision by providing suitable enabling
provisions and also covering certain general principles thereof.
All standards, whether given herein above or cross-referred to in the main text of this Section, are subject to
revision. The parties to agreement based on this Section are encouraged to investigate the possibility of applying
the most recent editions of the standards.
PART 6 STRUCTURAL DESIGN — SECTION 6 STEEL
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 6 Steel
1 SCOPE
1.1 This Section covers the use of structural steel in
general building construction including the use of hot
rolled steel sections and steel tubes.
1.2 The provisions of this Section are generally
applicable to rivetted, bolted and welded construction,
2 TERMINOLOGY
For the purpose of this Section, the definitions as given
in accepted standard [6-6(1)] shall apply.
3 PLANS AND DRAWINGS
3.1 Plans, drawings and stress sheets shall be prepared
according to good practice [6-6(2)].
3.2 Plans
The plans (design drawings) shall show the complete
design with sizes, sections, and the relative locations
of the various members. Floor levels, column centres,
and offsets shall be dimensioned. Plans shall be drawn
to a scale large enough to convey the information
adequately. Plans shall indicate the type of construction
to be employed; and shall be supplemented by such
data on the assumed loads, shears, moments and axial
forces to be resisted by all members and their
connections, as may be required for the proper
preparation of shop drawings. Any special precaution
to be taken in the erection of structure from the design
considerations, the same shall also be indicated in the
drawing.
3.3 Shop Drawings
Shop drawings, giving complete information necessary
for the fabrication of the component parts of the
structure including the location, type, size, length and
detail of all welds, shall be prepared in advance of the
actual fabrication. They shall clearly distinguish
between shop and field rivets, bolts and welds. For
additional information to be included on drawings for
designs based on the use of welding, reference shall
be made to appropriate Indian Standards. Shop
drawings shall be made in accordance with good
practice [6-6(2)]. A marking diagram allotting distinct
identification marks to each separate part of steel work
shall be prepared. The diagram shall be sufficient to
ensure convenient assembly and erection at site.
4 MATERIALS
All materials used in structural steel construction shall
conform to Part 5 'Building Materials' . Structural steel,
rivets, welding consumables, steel castings, bolts and
nuts, washers and steel tubes shall be in accordance
with accepted standards [6-6(3)] and other relevant
Indian Standards.
5 DESIGN AND CONSTRUCTION IN STEEL
The design and construction in steel including general
design requirements, design of tension members,
design of compression members, design of members
subjected to bending, design of members subjected to
combined stresses, design of connections, plastic
design, design of encased members, fabrication and
erection, and the steel work tenders and contracts, shall
be done in accordance with good practice [6-6(1)] and
the design and construction involving use of steel tubes
shall be in accordance with good practice [6-6(4)].
6 DESIGN USING LIMIT STATE METHOD
6.1 General
6.1.1 The design in steel may be done using the limit
state method, which is generally based on the following
basic aspects/principles:
a) It makes use of the plastic range of material
for the design of structural members and
incorporates load factors to take into account
the variability of loading configurations.
b) It considers the good performance of steel in
tension compared to compression and
specifies variable factors. It takes into account
this variance by defining limit states which
address strength and serviceability.
c) According to this method, a structure or part
of it, is considered unfit for use when it
exceeds the limit state beyond which it
infringes any one of the criteria governing its
performance or use.,,
d) The two limit states are classified as the
Ultimate Limit State and Serviceability Limit
State. The limit states take care of the safe
operation and adequacy of the structure from
strength point of view. The criteria which are
used to define the ultimate limit state are
yielding, plastic strength, fatigue, buckling,
etc. Serviceability limit state takes care of the
performance and behaviour of the structure
during its service period. Deflection, vibration,
drift, etc are considered as serviceability
criteria.
PART 6 STRUCTURAL DESIGN— SECTION 6 STEEL
e) Limit state method considers the critical local
buckling stress of the constituent plate
element of a member. This method has
provisions to enhance resistance of plate
elements against local buckling by suitably
reducing the slenderness ratio. Hence, it is
possible to develop the full flexural moment
capacity of a member subjected to flexure or
the Limit State in flexure for abeam. In Limit
State Method, based on slenderness ratio of
the constituent plate elements, a member can
be classified as Slender, Semi-compact,
Compact and Plastic. This section classification
becomes essential as the moment or load
capacities of each of these sections take
different values depending upon these
classifications.
6.1.2 In this method, the factored loads, in different
combinations, are applied to the structure to determine
the load effects. The latter are then compared with the
design strength of the elements.
This is expressed mathematically as:
The effects of
y L -&£
1
7m.
7l
Yt
7ml ' 7n
[Function of a and other geometric variables]
where
7m = 7r7ml*7m2
= Partial safety factor for material.
= Partial factor for loads.
Factor that takes into account the
inaccuracies in assessment of loads,
stress distribution and construction
tolerances.
, = Factors that take into account,
uncertainties in material strength and
quality, and manufacturing tolerances
respectively.
<2 k = Specified nominal load induced based
on design stipulations.
<x y = Yield strength of the material.
6.2 The detailed design procedure shall be as agreed
between the parties concerned.
NOTE — At the time of publication of this Section IS 800
was under revision and once the revised IS 800 is published,
the same shall replace the provisions given in this section.
7 SPACE FRAME
For analysis and design of space frame along with its
components, specialist literature may be referred to,
and the methodology for the same may be as agreed
between the parties concerned.
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and 'accepted standards'
in the fulfilment of the requirements of the Code. The
latest version of a standard shall be adopted at the time
of enforcement of the Code. The standards listed may
be used by the Authority as a guide in conformance
with the requirements of the referred clauses in the
Code.
In the following list, the number appearing in the first
column within parentheses indicates the number of the
reference in this Part/Section.
IS No.
(1) 800: 1984
(2) 962 : 1989
8000
Title
Code of practice for general
construction in steel (second
revision)
Code of practice for architectural
and building drawings (second
revision)
Geometrical tolerancing on
technical drawings:
IS No.
(Part 1) : 1985
(Part 2): 1992
(Part 3): 1992
(Part 4): 1976
IS 8976 : 1978
(3) Structural Steel
1977 : 1996
2062 : 1999
Title
Tolerances of form, orientation,
location and run-out, and
appropriate geometrical
definitions (first revision)
Maximum material principles
(first revision)
Dimensioning and tolerancing
of profiles (second revision)
Practical examples of indications
on drawings
Guide for preparation and
arrangement of sets of drawings
and parts list
Specification for low tensile
structural steels (third revision)
Specification for steel for
general structural purpose (fifth
revision)
NATIONAL BUILDING CODE OF INDIA
IS No.
Title
IS No.
8500:
1991
Specification for structural
steel-microalloyed (medium
and high tensile qualities) (first
revision)
Steel Castings
1030 : 1998
1161 ;
:1998
Specification for steel tubes
for structural purposes (third
revision)
2708 : 1993
Rivets
1929
: 1982
Specification for hot forged
steel rivets for hot closing
(12 to 36 mm diameter) (first
revision)
Bolts and Nuts
1363
2155;
; 1982
Specification for cold forged
solid steel rivets for hot closing
(6 to 16 mm diameter) (first
revision)
(Part 1) : 2002
(Part 2) : 2002
1148 :
1982
Specification for hot-rolled rivet
bars (up to 40 mm diameter)
for structural purposes (third
revision)
(Part 3) : 2002
1149:
1982
Specification for high tensile
steel rivet bars for structural
purposes (third revision)
IS 1364
Welding Consumables
1 278 : 1972 Specification for filler rods and
wires for gas welding (second
revision)
(Part 1) : 1992
(Part 2) : 2002
814:
1991
Specification for covered
electrodes for manual metal arc
welding of carbon and carbon
manganese steels (fifth revision)
IS 1367
(Part 1) : 2002
1395 : 1982 Specification for low and
medium alloy steel covered
electrodes for manual metal arc
welding (third revision)
7280 : 1974 Specification for bare wire
electrodes for submerged arc
welding of structural steels
3613 : 1974 Specification for acceptance
tests for wire-flux combinations
for submerged arc welding (first
revision)
6419 : 1996 Specification for welding rods
and bare electrodes for gas
shielded arc welding of
structural steel (first revision)
6560 : 1996 Specification for molybdenum
and chromium-molybdenum
low alloy steel welding rods and
bare electrodes for gas shielded
arc welding (first revision)
(Part 2) : 2002
IS 3640 : 1982
IS 3757 : 1985
IS 6623: 1985
IS 6639 : 1972
Washers
IS 5369: 1975
Title
Specification for carbon steel
castings for general engineering
purposes (fifth revision)
Specification for 1.5 percent
manganese steel castings for
general engineering purposes
(third revision)
Specification for hexagon head
bolts, screws and nuts of
product grade C:
Hexagon head bolts (size range
M5 to M64) (fourth revision)
Hexagon head screws (size
range M5 to M64) (fourth
revision)
Hexagon nuts (size range M5 to
M64) (fourth revision)
Specification for hexagon head
bolts, screws and nuts of
product grade A and B:
Hexagon head bolts (size range
Ml. 6 to M64) (fourth revision)
Hexagon head screws (size
range Ml. 6 to M64) (fourth
revision)
Technical supply conditions for
threaded steel fasteners:
General requirements for
bolts, screws and studs (third
revision)
Tolerances for fastners — Bolts,
screws, studs and nuts —
Product grades A, B and C
(third revision)
Specification for hexagon fit
bolts (first revision)
Specification for high strength
structural bolts (second
revision)
Specification for high strength
structural nuts (first revision)
Specification for hexagon bolts
for steel structures
General requirements for plain
washers and lock washers (first
revision)
PART 6 STRUCTURAL DESIGN — SECTION 6 STEEL
IS No.
Title
5370 : 1969
Specification for plain washers
with outside diameter more than
three times the diameter
5372 : 1975
Specification for taper washers
for channels (ISMC) (first
revision)
5374 : 1975
Specification for taper washers
for I-beams (ISMB) (first
revision)
IS No.
5624 : 1993
6610 : 1972
6649 : 1985
(4) 806 : 1968
Title
Specification for foundation
bolts (first revision)
Specification for heavy washers
for steel structures
Specification for hardened and
tempered washers for high
strength structural bolts and nuts
(first revision)
Code of use of steel tubes in
general building construction
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 7 Prefabrication, Systems Building and
Mixed/Composite Construction: 7A Prefabricated Concrete
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 MATERIALS, PLANS AND SPECIFICATIONS
4 MODULAR CO-ORDINATION, ARCHITECTURAL TREATMENT
AND FINISHES
5 COMPONENTS
6 PREFABRICATION SYSTEMS AND STRUCTURAL SCHEMES
7 JOINTS
8 TESTS FOR COMPONENTS/STRUCTURES
9 MANUFACTURE, STORAGE, TRANSPORT AND ERECTION OF
PRECAST ELEMENTS
10 EQUIPMENT
11 PREFABRICATED STRUCTURAL UNITS
LIST OF STANDARDS
5
5
6
6
7
8
12
13
14
20
21
21
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
Prefabrication, though desirable for large scale building activities, has yet to take a firm hold in the country. Two
aspects of prefabrication specifically to be borne in mind are the system to be adopted for the different categories
of buildings and the sizes of their components. Here the principle of modular co-ordination is of value and its use
is recommended.
Advantages of recent trends in prefabrication have been taken note of and also the hazards attended to such
construction. A few recommendations on the need to avoid 'progressive collapse' of the structure have been
included. This has become necessary in view of such collapses in the past. A specific point to be borne in mind,
therefore, is the need to make the structure reasonably safe against such a collapse.
Prefabricated constructions being comparatively a new technique, some of the essential requirements for the
manufacture of the prefabricated components and elements are also included in this Section.
Since the aim of prefabrication is to effect economy, improvement in quality and speed in construction, the
selection of proper materials for prefabrication is also an important factor in the popularization of this technique.
The use of locally available materials with required characteristics and those materials which, due to their innate
characteristics like lightweight, easy workability, thermal insulation, non-combustibility, etc, effect economy
and improved quality, may be tried. However, this Section pertains to prefabricated elements with cementatious
materials.
It is possible to achieve or evolve aesthetically satisfying designs using prefabricated construction. A careful and
judicious handling of materials and use of finishes on a prefabricated building can help the designer a great deal
in ensuring that the appearance of the building as aesthetically appealing. The purpose of finishes and architectural
treatment is not only to give prefabricated buildings an individual character but also to effect better performance
and greater user satisfaction.
The design of prefabricated buildings shall include provision for all installations of services and their required
piping, wiring and accessories to be installed in the building.
This Section was first published in 1970 and was subsequently revised in 1983. In the last revision the following
main changes were made:
a) A brief provision regarding importance of architectural treatment and finishes as applicable to
prefabricated buildings were included;
b) A brief clause was added on the requirements of materials for use in prefabrication;
c) The clause on prefabricating systems and structural elements was elaborated;
d) The clause on testing of components was revised to include testing of structure or part of structure; and
e) A brief clause on the manufacture of cellular concrete was added.
In this revision, this Section, earlier named as Prefabrication and Systems Building has been named and restructured
as follows:
Section 7 Prefabrication, Systems Building and Mixed/Composite Construction
7A Prefabricated Concrete
7B Systems Building and Mixed/Composite Construction
This sub-section covers Prefabricated concrete. In this revision the following main changes have been made:
a) Modular coordination and modular dimension of the components have been revised to have more
flexibility for planning.
b) The provisions on tolerance has been revised to include different types of prefabricated components.
PART 6 STRUCTURAL DESIGN — SECTION 7A PREFABRICATED CONCRETE
c) A detailed clause on design requirements for safety of prefabricated buildings against progressive clause
has been included.
d) A clause on sampling procedure has been added for testing of components.
e) List of Indian Standards referred as good practice has been updated, specially in view of formulation of
a large number of new Indian Standards on partially prefabricated components.
All standards cross-referred to in the main text of the sub-section, are subject to revision. The parties to agreement
based on this sub-section are encouraged to investigate the possibility of applying the most recent editions of the
standard.
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 7 Prefabrication, Systems Building and
Mixed/Composite Construction: 7A Prefabricated Concrete
1 SCOPE
This sub-section gives recommendations regarding
modular planning, component sizes, prefabrication
systems, design considerations, joints and manufacture,
storage, transport and erection of prefabricated
concrete elements for use in buildings and such related
requirements for prefabricated concrete.
2 TERMINOLOGY
2.1 For the purpose of this sub-section, the following
definitions shall apply.
2.1.1 Authority Having Jurisdiction — The Authority
which has been created by a statute and which, for the
purpose of administering the Code/Part, may authorize
a committee or an official or an agency to act on its
behalf; hereinafter called the 'Authority'.
2.1.2 Basic Module — The fundamental module used
in modular co-ordination, the size of which is selected
for general application to building and its components.
NOTE — The value of the basic module has been chosen as
100 mm for the maximum flexibility and convenience. The
symbol for the basic module is M.
2.1.3 Cellular Concrete — The material consisting of
an inorganic binder (such as, lime or cement or both)
in combination with a finely ground material
containing siliceous material (such as sand), gas
generating material (for example, aluminium powder),
water and harmless additives (optional); and steam
cured under high pressure in autoclaves.
2.1.4 Components — A building product formed as a
distinct unit having specified sizes in three dimensions.
2.1.5 Composite Members — Structural members
comprising prefabricated structural units of steel,
prestressed concrete or reinforced concrete and cast
in-situ concrete connected together in such a manner
that they act monolithic ally.
2.1.6 Increments — Difference between two
homologous dimensions of components of successive
sizes.
2.1.7 Light Weight Concrete — Concrete of
substantially lower unit weight than that made from
gravel or crushed stone.
2.1.8 Module — A unit of size used in dimensional
co-ordination.
2.1.9 Modular Co-ordination — Dimensional
co-ordination employing the basic module or a multi-
module.
NOTE — The purposes of modular co-ordination are;
a) to reduce the variety of component sizes produced, and
b) to allow the building designer greater flexibility in the
arrangement of components.
2.1.10 Modular Grid — A rectangular coordinate
reference system in which the distance between
consecutive lines is the basic module or a multi-
module. This multi-module may differ for each of the
two dimensions of the grid.
2.1.11 Multi-module — A module whose size is a
selected multiple of the basic module.
2.1.12 Prefabricate — To fabricate components or
assembled units prior to erection or installation in a
building.
2.1.13 Prefabricated Building — The partly/fully
assembled and erected building, of which the structural
parts consist of prefabricated individual units or
assemblies using ordinary or controlled materials,
including service facilities; and in which the service
equipment may be either prefabricated or constructed
in-situ.
2.1.14 Sandwich Concrete Panels — Panels made by
sandwiching an insulation material between two layers
of reinforced concrete to act as insulation for concrete
panels.
2.1.15 Self Compacting Concrete — Concrete that is
able to flow under its own weight and completely fill
the voids within the formwork, even in the presence
of dense reinforcement without any vibration, whilst
maintaining homogeneity without segregation.
2.1.16 Shear Connectors — Structural elements, such
as anchors, studs, channels and spirals, intended to
transmit the horizontal shear between the prefabricated
member and the cast in-situ concrete and also to
prevent vertical separation at the interface.
2.1.17 System — It is a particular method of
construction of buildings with certain order and
discipline using the prefabricated components, tunnel
form or large panel shutters which are inter-related in
functions and are produced based on a set of
instructions.
2.1.18 Unit — Building material formed as a simple
article with all three dimensions specified, complete
PART 6 STRUCTURAL DESIGN — SECTION 7A PREFABRICATED CONCRETE
in itself but intended to be part of a compound unit or
complete building. Examples are brick, block, tile, etc.
3 MATERIALS, PLANS AND SPECIFICATIONS
3.1 Materials
further work is necessary to outline suitable range of
multi-modules with greater increments, often referred
to as preferred increments. A set of rules as detailed
below would be adequate for meeting the requirements
of conventional and prefabricated construction.
All materials shall conform to Part 5 'Building Materials' . These mles relate to me following basic elements:
3.1.1 While selecting the materials for prefabrication,
the following characteristics shall be considered:
a) Easy availability;
b) Light weight for easy handling and transport;
c) Thermal insulation property;
d) Easy workability;
e) Durability;
f) Non-combustibility;
g) Sound insulation;
h) Economy; and
j) Any other special requirement in a particular
application.
3.2 Plans and Specifications
The detailed plans and specifications shall cover the
following:
a) Such drawings shall describe the elements and
the structure and assembly including all
required data of physical properties of
component materials. Material specification,
age of concrete for demoulding, casting/erection
tolerance and type of curing to be followed.
b) Details of connecting joints of prefabricates
shall be given to an enlarged scale.
c) Site or shop location of services, such as
installation of piping, wiring or other
accessories integral with the total scheme shall
be shown separately.
d) Data sheet indicating the location of the inserts
and acceptable tolerances for supporting the
prefabricate during erection, location and
position of doors/windows/ventilators, etc, if
any.
e) The drawings shall also clearly indicate
location of handling arrangements for lifting
and handling the prefabricated elements.
Sequence of erection with critical check points
and measures to avoid stability failure during
construction stage of the building.
4 MODULAR CO-ORDINATION,
ARCHITECTURAL TREATMENT AND
FINISHES
4.1 Modular Co-ordination
The basic module is to be adopted. After adopting this,
a) The planning grid in both directions of the
horizontal plan shall be:
1) 15 Af for industrial buildings,
2) 3 Af for other buildings.
The centre lines of load bearing walls should
preferably coincide with the gridlines.
b) The planning module in the vertical direction
shall be 2 Af for industrial buildings and 1 M
for other buildings.
c) Preferred increments for sill heights, doors,
windows and other fenestration shall be 1 M.
d) In the case of internal columns, the grid lines
shall coincide with the centre lines of
columns. In case of external columns and
columns near the lift and stair wells, the grid
lines shall coincide with centre lines of the
column in the topmost storey.
4.2 Architectural Treatment and Finishes
Treatment and finishes have to be specified keeping
in view the requirements of protection, function and
aesthetics of internal and external spaces and surfaces.
While deciding the type of architectural treatment and
finishes for prefabricated buildings, the following
points should be kept in view:
a) Suitability for mass production techniques;
b) Recognition of the constraints imposed by the
level of workmanship available;
c) Possibility of using different types of finishes;
d) Use of finishes and architectural treatment
for the creation of a particular architectural
character in individual buildings and in
groups of buildings by the use of colour,
texture, projections and recesses on surfaces,
etc;
e) Incorporation of structural elements like
joists, columns, beams, etc, as architectural
features and the treatment of these for better
overall performance and appearance;
f) Satisfactory finishing of surfaces; and
g) Use of light weight materials to effect
economy in the structural system.
Some of the acceptable methods of finishes integral
with the precasting are:
a) Concrete surface moulded to design; shape;
NATIONAL BUILDING CODE OF INDIA
b) Laid-on finishing tiles fixed during casting;
c) Finishes obtained by washing, tooling,
grinding, grooving of hardened concrete;
d) Exposed aggregates; and
e) Other integral finishes.
5 COMPONENTS
5. 1 The preferred dimensions of precast elements shall
be as follows:
a) Flooring and Roofing Scheme — Precast
slabs or other precast structural flooring
units:
1) Length — Nominal length shall be in
multiples of 1 M;
2) Width — Nominal width shall be in
multiples of 0.5 M; and
3) Overall Thickness — Overall thickness
shall be in multiples of 0. 1 M.
b) Beams
1) Length — Nominal length shall be in
multiples of 1 M;
2) Width — Nominal width shall be in
multiples of 0.1 M; and
3) Overall Depth — Overall depth of
the floor zone shall be in multiples of
0.1 M.
c) Columns
1) Height — Height of columns for
industrial and other building 1 M; and
2) Lateral Dimensions — Overall lateral
dimension or diameter of columns shall
be in multiples of 0. 1 M.
d) Walls
Thickness — The nominal thickness of walls
shall be in multiples of 0.1 M.
e) Staircase
Width — Nominal width shall be in multiples
of 1M.
f) Lintels
1) Length — Nominal length shall be in
multiples of 1 M;
2) Width — Nominal width shall be in
multiples of 0. 1 M; and
3) Depth — Nominal depth shall be in
multiples of 0. 1 M.
g) Sunshade s/Chajja Projections
1) Length — Nominal length shall be in
multiples of 1 M.
2) Projection — Nominal length shall be in
multiples of 0.5 M.
5.2 Casting Tolerances of Precast Components
SI
No.
(1)
Product Tolerances
(2)
Product
(see
Note)
(3)
i) Length
±5 mm 1, 7
± 5 mm or ± 0.1 percent whichever is 2, 3, 8
greater
± 0.1 percent subject to maximum 4
of _|^mm
± 2 mm for length below and up to 5
500 mm
± 5 mm for length over 500 mm 5
±10 mm 6,9,10
ii) Thickness/Cross-sectional dimensions
±3 mm 1
± 3 mm or 0.1 percent whichever is 2, 8
greater
± 2 mm up to 300 mm wide ,
± 3 mm greater than 300 mm wide
±2 mm 3,7
±4 mm 6,9,10
iii) Straightness/Bow
± 5 mm or 1/750 of length whichever 2, 4, 8
is greater
±3 mm 1, 5
±2mm 7
iv) Squareness
When considering the squareness of
the corner, the longer of two adjacent
sides being checked shall be taken as
the base line.
The shorter side shall not vary in 2, 5, 8
length from the perpendicular by
more than 5 mm
The shorter side shall not vary in 1,7
length from the perpendicular by
more than 3 mm
The shorter side shall not be out of 4
+2
square line for more than _- mm
v) Twist
Any corner shall not be more than
the tolerance given below from the
plane containing the other three
corners:
± 5 mm (Up to 600 mm in width and 2, 8
up to 6 m in length)
±10 mm (Over 600 mm in width and
for any length)
± 1/1 500 of dimension of ± 5 mm 4
whichever is less
PART 6 STRUCTURAL DESIGN — SECTION 7A PREFABRICATED CONCRETE
(1)
(2)
(3)
±3 mm
± 1 mm
vi) Flatness
The maximum deviation from 1.5 m
straight edge placed in any position
on a nominal plane surface shall not
exceed
± 5 mm 2, 8
±3 mm 4
±2 mm 1,7
± 4 or maximum of 0. 1 percent 5
length
NOTES — Key for product reference
1 Channel unit
2 Ribbed slab unit/hollow slab
3 Waffle unit
4 Large panel prefabrication
5 Cellular concrete floor/roof slabs
6 Prefabricated brick panel
7 Precast planks
8 Ribbed/plain wall panel
9 Column
10 Step unit
6 PREFABRICATION SYSTEMS
STRUCTURAL SCHEMES
AND
6.1 The word 'system' is referred to a particular
method of construction of buildings using the
prefabricated components which are inter-related in
functions and are produced to a set of instructions. With
certain constraints, several plans are possible, using
the same set of components. The degree of flexibility
varies from system to system. However, in all the
systems there is a certain order and discipline.
6.2 The following aspects, among others, are to be
considered in devising a system:
a) Effective utilization of spaces;
b) Straight and simple walling scheme;
c) Limited sizes and numbers of components;
d) Limited opening in bearing walls;
e) Regulated locations of partitions;
f) Standardized service and stair units;
g) Limited sizes of doors and windows with
regulated positions;
h) Structural clarity and efficiency;
j) Suitability for adoption in low rise and high
rise building;
k) Ease of manufacturing, storing and
transporting;
m) Speed and ease of erection; and
n) Simple jointing system.
6.3 Prefabrication Systems
The system of prefabricated construction depends on
the extent of the use of prefabricated components, their
materials, sizes and the technique adopted for their
manufacture and use in building.
6.3.1 Types of Prefabrication Components
The prefabricated concrete components such as those
given below may be used which shall be in accordance
with Part 5 'Building Materials' and the accepted
standards [6-7A(l)], where available:
a) Reinforced/Prestressed concrete channel unit,
b) Reinforced/Prestressed concrete slab unit,
c) Reinforced/Prestressed concrete beams,
d) Reinforced/Prestressed concrete columns,
e) Reinforced/Prestressed concrete hollow core
slab,
f) Reinforced concrete waffle slab/shells,
g) Reinforced/Prestressed concrete wall
elements,
h) Hollow/Solid blocks and battens,
j) Precast planks and joists for flooring and
roofing,
k) Precast joists and trussed girders,
m) Light weight/cellular concrete slabs,
n) Precast lintel and chajjas,
p) Large panel prefabricates,
q) Reinforced/Prestressed concrete trusses,
r) Reinforced/Prestressed roof purlins,
s) Precast concrete L-panel unit,
t) Prefabricated brick panel unit,
u) Prefabricated sandwich concrete panel, and
v) Precast foundation.
There may be other types of components which may
be used with the approval of the Authority.
NOTE — The elements may be cast at the site or off the site.
6.3.2 There are two categories of open prefab system
depending on the extent of prefabrication used in the
construction as given in 6.3,2.1 and 6.3.2.2.
6.3.2.1 Partial prefabrication system
This system basically uses precast roofing and flooring
components and other minor elements like lintels,
CHAJJAS, kitchen sills in conventional building
construction. The structural system could be in the form
of in-situ framework or load bearing walls.
6.3.2.2 Full prefabrication system
In this system almost all the structural components are
prefabricated. The filler walls may be of brick/block
masonry or of any other locally available material.
NATIONAL BUILDING CODE OF INDIA
6.3.3 Large Panel Prefabrication System
This system is based on the use of large prefab
components. The components used are precast concrete
large panels for walls, floors, roofs, balconies,
staircases, etc. The casting of the components could
be at the site or off the site.
Depending upon the extent of prefabrication, this
system can also lend itself to partial prefab system and
full prefab system.
Structural scheme with precast large panel walls can
be classified as given in 6.3.3.1 to 6.3.3.3.
6.3.3.1 Precast Walls
6.3.3.1.1 Based on the structural functions of the walls,
the precast walls may be classified as:
a) load bearing walls,
b) non-load bearing walls, and
c) shear walls.
6.3.3.1.2 Based on construction, the precast walls may
be classified as:
a) Homogeneous walls — which could be solid,
hollow or ribbed; and
b) Non-homogeneous walls — these could be
composite or sandwich panels.
6.3.3.1.3 Based on their locations and functional
requirements the precast walls may also classified as:
a) external walls, which may be load bearing or
non-load bearing depending upon the lay-out;
these are usually non-homogeneous walls of
sandwiched type to impart better thermal
comforts; and
b) internal walls providing resistance against
vertical loads, horizontal loads, fire, etc; these
are normally homogeneous walls.
6.3.3.2 Precast floors
6.3.3.2.1 Depending upon the composition of units,
precast flooring units may be homogeneous or non-
homogeneous,
a) Homogeneous floors may be solid slabs,
cored slabs, ribbed or waffle slabs.
b) Non-homogeneous floors may be multi-
layered ones with combinations of light
weight concrete or reinforced/prestressed
concrete, with filler blocks.
6.3.3.2.2 Depending upon the way the loads are
transferred, the precast floors may be classified as one
way or two way systems:
a) One way system transfers loads to supporting
members in one direction only. The precast
elements which come under this category are
channel slabs, hollow core slabs, channels and
ties system, light weight/cellular concrete
slabs, etc.
b) Two way systems transfer loads in both the
directions imparting loads on the four edges.
The precast elements under this category are
room sized panels, two way ribbed or waffle
slab systems, etc.
6.3.3.3 Staircase systems
Staircase system may consist of single flights with in-
built risers and treads in the element. The flights are
normally unidirectional transferring the loads to
supporting landing slabs or load bearing walls.
6.3.4 Box Type Construction
In this system, room size units are prefabricated and
erected at site. Toilet and kitchen blocks could also be
similarly prefabricated and erected at site.
NOTE — This system derives its stability and stiffness from
the box units which are formed by four adjacent walls. Walls
are jointed to make rigid connections among themselves. The
box unit rests on foundation which may be of conventional
type or precast type,
6.4 Design Considerations
The precast structure should be analyzed as a
monolithic one and the joints in them designed to take
the forces of an equivalent discrete system. Resistance
to horizontal loading shall be provided by having
appropriate moment and shear resisting joints or
placing shear walls (in diaphragm braced frame type
of construction) in two directions at right angles or
otherwise. No account is to be taken of rotational
stiffness, if any, of the floor- wall joint in case of precast
bearing wall buildings. The individual components
shall be designed, taking into consideration the
appropriate end conditions and loads at various stages
of construction. The components of the structure shall
be designed for loads in accordance with Part 6
'Structural Design, Section 1 Loads, Forces and
Effects'. In addition members shall be designed for
handling, erection and impact loads that might be
expected during handling and erection.
6.4.1 In some conventional forms of construction,
experience has shown that the structures are capable
of safely sustaining abnormal conditions of loading
and remaining stable after the removal of primary
structural members. It has been shown that some
forms of building structure and particularly some
industrialized large panel systems have little reserve
strength to resist forces not specifically catered
for in the design. In the light of this, therefore,
recommendations made in 6.4.2 to 6.4.9 should be kept
in mind for ensuring stability of such structure.
PART 6 STRUCTURAL DESIGN — SECTION 7A PREFABRICATED CONCRETE
6.4.2 Adequate buttressing of external wall panels is
important since these elements are not fully restrained
on both sides by floor panels. Adequate design
precautions may be taken by the designer. Experience
shows that the external wall panel connections are the
weakest points of a precast panel building.
6.4.3 It is equally important to provide restraint to all
load bearing elements at the corners of the building.
These elements and the external ends of cross-wall
units should be stiffened either by introducing columns
as connecting units or by jointing them to non-
structural wall units which in emergency may support
the load. Jointing of these units should be done bearing
in mind the need for load support in an emergency.
6.4.4 In prefabricated construction, the possibility of
gas or other explosions which can remove primary
structural elements leading to progressive collapse of
the structure shall be taken into account. It is, therefore,
necessary to consider the possibility of progressive
collapse in which the failure or displacement of one
element of a structure causes the failure or displacement
of another element and results in the partial or total
collapse of the building.
6.4.5 Provision in the design to reduce the probability
of progressive collapse is essential in buildings of over
six storeys and is of relatively higher priority than for
buildings of lower height.
6.4.6 It is necessary to ensure that any local damage
to a structure does not spread to other parts of the
structure remote from the point of mishap and that the
overall stability is not impaired, but it may not be
necessary to stiffen all parts of the structure against
local damage or collapse in the immediate vicinity of
a mishap, unless the design briefs specifically requires
this to be done.
6.4.7 Additional protection may be required in respect
of damage from vehicles; further, it is necessary to
consider the effect of damage to or displacement of a
load-bearing member by an uncontrolled vehicle. It is
strongly recommended that important structural
members are adequately protected by concrete kerbs
or similar method.
6.4.8 In all aspects of erection that affect structural
design, it is essential that the designer should maintain
a close liaison with the builder/contractor regarding
the erection procedures to be followed.
6.4.9 Failures that have occurred during construction
appear to be of two types. The first of these is the pack-
of-cards type of collapse in which the absence of
restraining elements, such as partitions, cladding or
shear walls, means that the structure is not stable during
the construction period. The second is the situation in
which one element falls during erection and lands on
an element below. The connections of the lower
element then give way under the loading, both static
and dynamic, and a chain reaction of further collapse
is set up.
6.4.9.1 A precaution against the first form of failure
is that the overall stability of a building shall be
considered in all its erection stages as well as in its
completed state. All joints that may be required to resist
moments and shears during the erection stage only,
shall be designed with these in mind. Temporary works
required to provide stability during construction shall
be designed carefully.
6.4.9.2 To guard against the second form of failure,
that is, the dropping of a unit during erection, particular
attention shall be given to the details of all pre-formed
units and their seatings to ensure that they are
sufficiently robust to withstand the maximum stresses
that can arise from site conditions. Precast concrete
construction generally shall be capable of withstanding
the impact forces that can arise from bad workmanship
on site.
6.5 Design Requirements for Safety Against
Progressive Collapse
6.5.1 Prefabricated buildings shall be designed with
proper structural integrity to avoid situations where
damage to small areas of a structure or failure of single
elements may lead to collapse of major parts of the
structure.
The following precaution may generally provide
adequate structural integrity:
a) All buildings should be capable of safely
resisting the minimum horizontal load of 1.5
percent of characteristic dead load applied at
each floor or roof level simultaneously (see
Fig. 1).
c
DESIGN r*~
WIND/ •*-"
SEISMIC p"
LOAD ^""
r
0.015 g k4
0.015 g k3
0*15 g„7
o.oisg k1
9 k = Characteristic dead load
Fig. 1 Horizontal Loads
b) All buildings are provided with effective
horizontal ties
1 ) Around the periphery
2) Internally (in both directions)
3) To columns and walls
10
NATIONAL BUILDING CODE OF INDIA
c) Vertical ties for buildings of five or more
storeys.
In proportioning the ties, it may be assumed that no
other forces are acting and the reinforcement is acting
at its characteristic strength.
Normal procedure may be to design the structure for
the usual loads and then carry out a check for the tie
forces.
6.5.2 Continuity and Anchorage of Ties
Bars shall be lapped, welded or mechanically joined
as in accordance with Part 6 'Structural Design, Section
5 Plain, Reinforced and Prestressed Concrete: 5 A Plain
and Reinforced Concrete'.
6.5.3 Design of Ties
6.5.3.1 Peripheral ties
At each floor and roof level an effectively continuous
tie should be provided within 1.2 m of the edge of the
building or within the perimeter wall (see Fig. 2).
The tie should be capable to resisting a tensile force of
F t equal to 60 kN or (20 + 4AT) kN whichever is less,
where N is the number of storeys (including basement)
CLADDING
NOTE — If there are cantilever slabs, supporting external
cladding, projecting in front of the columns and these are more
than 1.2 m, than the peripheral tie shall go in the slab.
Fig. 2 Position for Peripheral Tie
6.5.3.2 Internal ties
These are to be provided at each floor and roof level
in two directions approximately at right angles. Ties
should be effectively continuous throughout their
length and be anchored to the peripheral tie at both
ends, unless continuing as horizontal ties to columns
or walls (see Fig. 3). The tensile strength, in kN/m
width shall be the greater of
7.5 5
and 1.5 F
where (g k + q k ) is the sum of average characteristic
dead and imposed floor loads in kN/m 2 and / r is the
greater of the distance between the centre of columns,
frames or walls supporting any two adjacent floor spans
in the direction of the tie under consideration.
The bars providing these ties may be distributed evenly
in the slabs (see Fig. 4) or may be grouped at or in the
beams, walls or other appropriate positions but at
spacings generally not greater than 1.5 / r .
6.5.3.3 Horizontal ties to column and wall
All external load-bearing members such as columns
and walls should be anchored or tied horizontally into
the structure at each floor and roof level. The design
force for the tie is to be greater of:
a) 2 F t kN or l $ x F/2.5 kN whichever is less for
a column or for each metre length if there is a
wall /, is the floor to ceiling height in metres.
b) 3 percent of the total ultimate vertical load in
the column or wall at that level.
For corner columns, this tie force should be provided
in each of two directions approximately at right angles.
6.5.3.4 Vertical ties (for buildings of five or more
storeys)
Each column and each wall carrying vertical load
should be tied continuously from the foundation to the
roof level. The reinforcement provided is required only
to resist a tensile force equal to the maximum design
ultimate load (dead and imposed) received from any
one storey.
In situation where provision of vertical ties cannot be
done, the element should be considered to be removed
and the surrounding members designed to bridge the
gap.
6.5.4 Key Elements
For buildings of five or more storeys, the layout should
be checked to identify key elements. A key element is
such that its failure would cause the collapse of more
than a limited area close to it.
The limited area defined above may be taken equal to
70 m 2 or 15 percent of the area of the storey whichever
is lesser.
If key elements exists, it is preferable to modify the
layout so that the key element is avoided.
6.6 Bearing for Precast Units
Precast units shall have a bearing at least of 100 mm
on masonry supports and of 75 mm at least on steel or
concrete. Steel angle shelf bearings shall have a
100 mm horizontal leg to allow for a 50 mm bearing
exclusive of fixing clearance. When deciding to what
extent, if any, the bearing width may be reduced in
special circumstances, factors, such as, loading, span,
height of wall and provision of continuity, shall be
taken into consideration.
PART 6 STRUCTURAL DESIGN — SECTION 7A PREFABRICATED CONCRETE
11
■ADDITIONAL BAR
FOR PERIPHERAL TIE
•/
i
E
i
-EXTENDED
TiE BARS
NOTE — If the peripheral tie consists of bars in an edge beam, then the bottom bars in the slabs will not be
at the same level as the peripheral tie bars. It is suggested that either an additional bar be used for the
peripheral tie or the internal tie bars be extended and anchored around the top bar in the beam.
Fig. 3 Anchoring of Ties in Slabs
t
l
NOTE — For continuity in continuous slabs, bars are distributed evenly in a floor slab by means of lapping
some bottom steel at supports, either by extending existing bars or by the addition of splice bars.
Fig. 4 Continuity Requirement for Slab
7 JOINTS
7.1 The design of joints shall be made in the light of
their assessment with respect to the following
considerations:
a) Feasibility — The feasibility of a joint shall
be determined by its load-carrying capacity
in the particular situation in which the joint is
to function.
b) Practicability — Practicability of joint shall
be determined by the amount and type of
material required in construction; cost of
material, fabrication and erection and the time
for fabrication and erection.
c) Serviceability — Serviceability shall be
determined by the joints/expected behaviour
to repeated or possible overloading and
exposure to climatic or chemical conditions.
d) Fire Rating — The fire rating for joints of
precast components shall be higher or at least
equal to connecting members.
e) Appearance — The appearance of precast
components joint shall merge with
architectural aesthetic appearance and shall
not be physically prominent compared to
other parts of structural components.
7.2 The following are the requirements of a structural
joint:
a)
b)
c)
d)
e)
f)
g)
h)
It shall be capable of being designed to
transfer the imposed load and moments with
a known margin of safety;
It shall occur at logical locations in the
structure and at points which may be most
readily analysed and easily reinforced;
It shall accept the loads without marked
displacement or rotation and avoid high local
stresses;
It shall accommodate tolerances in elements;
It shall require little temporary support, permit
adjustment and demand only a few distinct
operation to make;
It shall permit effective inspection and
rectification;
It shall be reliable in service with other parts
of the building; and
It shall enable the structure to absorb
sufficient energy during earthquakes so as to
avoid sudden failure of the structure.
7.2.1 Precast structures may have continuous or
hinged connections subject to providing sufficient
rigidity to withstand horizontal loading. When only
compressive forces are to be taken, hinged joints may
be adopted. In case of prefabricated concrete elements,
load is transmitted via the concrete. When both
compressive force and bending moment are to be taken,
12
NATIONAL BUILDING CODE OF INDIA
rigid or welded joints may be adopted; the shearing
force is usually small in the column and can be taken
up by the friction resistance of the joint. Here load
transmission is accomplished by steel inserted parts
together with concrete.
7.2.2 When considering thermal shrinkage and heat
effects, provision of freedom of movement or
introduction of restraint may be considered.
7.3 Joining techniques/materials normally employed
are:
a) Welding of cleats or projecting steel,
b) Overlapping reinforcement, loops and linking
steel grouted by concrete,
c) Reinforced concrete ties all round a slab,
d) Prestressing,
e) Epoxy grouting,
Bolts and nuts connection,
g) A combination of the above, and
h) Any other method proven by test.
8 TESTS FOR COMPONENTS/STRUCTURES
8.1 Sampling Procedure
8.1.1 Lot
All the precast units of the same size, manufactured from
the same material under similar conditions of production
shall be grouped together to constitute a lot.
The number of units to be selected from each lot for
dimensional requirements shall depend upon the size
of the lot and shall be in accordance with col 1 and 2
of Table 1.
Table 1 Sample Size and Rejection Number
(Clauses 8.1.1 and 8.1.2)
Lot Size
(1)
First Second First Second
Sample Sample Rejection Rejection
Size Size Number Number
(2)
(3)
(4)
(5)
Up to 100
5
5
2
2
101 to 300
8
8
2
2
301 to 500
13
13
2
2
500 and above
20
20
3
4
The units shall be selected from the lot at random. In
order to ensure the randomness of selection, reference
may be made to good practice [6-7 A(2)].
8.1.2 Number of Tests and Criteria for Conformity
All the units selected at random in accordance with
col 1 and 2 of Table 1 shall be subjected to the
dimensional requirements. A unit failing to satisfy any
of the dimensional requirements shall be termed as
defective. The lot shall be considered as conforming
to the dimensions requirements if no defective is found
in the sample, and shall be rejected if the number of
defectives is greater than or equal to the first rejection
number. If the number of defectives is less than the
first rejection number the second sample of the same
size as taken in the first stage shall be selected from
the lot at random and subjected to the dimensional
requirements. The number of defectives in the first
sample and the second sample shall be combined and
if the combined number of defectives is less than the
second rejection number, the lot shall be considered
as conforming to the dimensional requirements;
otherwise not.
The lot which has been found as satisfactory with
respect to the dimensional requirements shall then be
tested for load test. For this purpose one unit shall be
selected for every 300 units or part thereof. The lot
shall be considered as conforming to the strength
requirement if all the units meet the requirement;
otherwise not.
8.2 Testing on Individual Components
The component should be loaded for one hour at its
full span with a total load (including its own self
weight) of 1.25 times the sum of the dead and imposed
loads used in design. At the end of this time it should
not show any sign of weakness, faulty construction or
excessive deflection. Its recovery one hour after the
removal of the test load, should not be less than 75
percent of the maximum deflection recorded during
the test. If prestressed, it should not show any visible
cracks up to working load and should have a recovery
of not less than 85 percent in 1 h.
8.3 Load Testing of Structure or Part of Structure
Loading test on a completed structure should be made
if required by the specification or if there is a
reasonable doubt as to the adequacy of the strength
of the structure.
8.3.1 In such tests the structure should be subjected
to full dead load of the structures plus an imposed load
equal to 1 .25 times the specified imposed load used in
design, for a period of 24 ft and then the imposed load
shall be removed. During the tests, vertical struts equal
in strength to take the whole load should be placed in
position leaving a gap under the member.
NOTE — Dead load includes self weight of the structural
members plus weight of finishes and walls or partitions, if any,
as considered in the design.
8.3.1.1 If within 24 h of the removal of the load, a
reinforced concrete structure does not show a recovery
df at least 75 percent of the maximum deflection shown
during the 24 h under load, test loading should be
repeated after a lapse of 72 h. If the recovery is less
PART 6 STRUCTURAL DESIGN — SECTION 7A PREFABRICATED CONCRETE
13
than 80 percent in second test, the structure shall be
deemed to be unacceptable.
8.3.1.2 If within 24 h of the removal of the load,
prestressed concrete structure does not show a recovery
of at least 85 percent of the maximum deflection shown
during the 24 h under load, the test loading should be
repeated. The structure should be considered to have
failed, if the recovery after the second test is not at
least 85 percent of the maximum deflection shown
during the second test.
8.3.1.3 If the maximum deflection in mm, shown
during 24 h under load is less than 40 P/D, where / is
the effective span in m; and £>, the overall depth of the
section in mm, it is not necessary for the recovery to
be measured and the recovery provisions of 8.3.1.1
and 8.3.1.2 shall not apply.
9 MANUFACTURE, STORAGE, TRANSPORT
AND ERECTION OF PRECAST ELEMENTS
9.1 Manufacture of Precast Concrete Elements
9.1.1 A judicious location of precasting yard with
concreting, initial curing (required for demoulding),
storage facilities, suitable transporting and erection
equipments and availability of raw materials are the
crucial factors which should be carefully planned and
provided for effective and economic use of precast
concrete components in constructions.
9.1.2 Manufacture
The manufacture of the components can be done in a
factory for the commercial production established at
the focal point based on the market potential or in a
site precasting yard set up at or near the site of work.
9.1.2.1 Factory prefabrication
Factory prefabrication is resorted to in a factory for
the commercial production for the manufacture of
standardized components on a long-term basis. It is a
capital intensive production where work is done
throughout the year preferably under a closed shed to
avoid effects of seasonal variations. High level of
mechanization can always be introduced in this system
where the work can be organized in a factory-like
manner with the help of a constant team of workmen.
9.1.2.2 Site prefabrication
Prefabricated components produced at site or near the
site of work as possible.
This system is normally adopted for a specific job order
for a limited period. Under this category there are two
types that is semi-mechanized and fully-mechanized.
9.1.2.2.1 Semi-mechanized
The work is normally carried out in open space with
locally available labour force. The equipment
machinery used may be minor in nature and moulds
are of mobile or stationary in nature.
9.1.2.2.2 Fully-mechanized
The work will be carried out under shed with skilled
labour. The equipments used will be similar to one of
factory production. This type of precast yards will be
set up for the production of precast components of high
quality, high rate of production.
Though there is definite economy with respect to cost
of transportation, this system suffers from basic
drawback of its non-suitability to any high degree of
mechanization and no elaborate arrangements for
quality control. Normal benefits of continuity of work
is not available in this system of construction.
9.1.3 The various processes involved in the
manufacture of precast elements may be classified as
follows:
9.1.3.1 Main process
a) Providing and assembling the moulds, placing
reinforcement cage in position for reinforced
concrete work, and stressing the wires in the
case of prestressed elements;
b) Fixing of inserts and tubes, where necessary
(for handling);
c) Pouring the concrete into the moulds;
d) Vibrating the concrete and finishing;
e) Curing (steam curing, if necessary); and
f) Demoulding the forms and stacking the
precast products.
9.1.3.2 Auxiliary process
Process necessary for the successful completion of the
processes covered by the main process:
a) Mixing and manufacture of fresh concrete
(done in a mixing station or by a batching
plant);
b) Prefabrication of reinforcement cage (done in
a steel yard or workshop);
c) Manufacture of inserts and other finishing
items to be incorporated in the main precast
products;
d) Finishing the precast products; and
e) Testing of products.
9.1.3.3 Subsidiary process
All other work involved in keeping the main production
work to a cyclic working:
a) Storage of materials;
b) Transport of cement and aggregates;
14
NATIONAL BUILDING CODE OF INDIA
c) Transport of green concrete and reinforcement
cages;
d) Transport and stacking the precast elements;
e) Repairs and maintenance of tools, tackles and
machines;
f) Repairs and maintenance of moulds, and
g) Generation of steam, etc.
9.1.4 For the manufacture of precast elements all the
above processes shall be planned in a systematic way
to achieve the following:
a) A cyclic technological method of working to
bring in speed and economy in manufacture;
b) Mechanization of the process to increase
productivity and to improve quality;
c) The optimum production satisfying the
quality control requirements and to keep up
the expected speed of construction aimed;
d) Better working conditions for the people on
the job; and
e) To minimize the effect of weather on the
manufacturing schedule.
9.1.5 The various stages of precasting can be classified
as in Table 2 on the basis of the equipments required
for the various stages. This permits mechanization and
rationalization of work in the various stages. In the
precasting, stages 6 and 7 given in Table 2 form the
main process in the manufacture of precast concrete
elements. For these precasting stages there are many
technological processes to suit the concrete product
under consideration which have been proved rational,
economical and time saving. The technological line or
process is the theoretical solution for the method of
planning the work involved by using machine
complexes. Figure 5 illustrates diagramatically the
various stages involved in a plant process.
FINE COARSE
AGGREGATE AGGREGATE
MILD STEEL
H.T.WIRE
| CURING IN YARD |
-c
TESTING
BY ROAD -* | DESPATCH |— — *- BY RAH.
Fig. 5 Plant Process
PART 6 STRUCTURAL DESIGN — SECTION 7A PREFABRICATED CONCRETE
15
Table 2 Stages of Precasting of Concrete Products
[Clauses 9.1.5 and 9.1 1(g)]
SI
No.
Precasting
Stage No.
Name of Process
(1)
: (2)
(3)
i)
1
Procurement and storage of
construction materials
ii)
2
Testing of raw materials
iii)
3
Design of concrete mix
Operations Involved
(4)
iv) 4 Making of reinforcement cages
Applying form release agent and
laying of moulds in position
Placing of reinforcement cages,
inserts and fixtures
Preparation of green concrete
Transport of green concrete
ix) 9 Pouring and consolidation of
concrete
x) 1 Curing of concrete and demoulding
v)
5
vi)
6
vii)
7
viii)
8
xi) 1 1 Stacking of precast elements
xii) 12 Testing of finished components
xii i) 13 Miscellaneous
Unloading and transport of cement, coarse and the aggregates, and steel, and
storing them in bins, silos or storage sheds
Testing of all materials including steel
Testing of raw materials, plotting of grading curves and trial of mixes in
laboratory
Unloading of reinforcement bars from wagons or lorries and stacking them in
the steel yard, cutting, bending, tying or welding the reinforcements and
making in the form of a cage, which can be directly introduced into the mould.
Moulds are cleaned, applied with form release agent and assembled and placed
at the right place.
The reinforcement cages are placed in the moulds with spacers, etc as per data
sheet prepared for the particular prefabricate.
Taking out aggregates and cement from bins, silos, etc, batching and mixing.
Transport of green concrete from the mixer to the moulds. In the case of
precast method involving direct transfer of concrete from mixer to the mould
or a concrete hopper attached to the mould this prefabrication stage is not
necessary.
Concrete is poured and vibrated to a good finish.
Either a natural curing with water or an accelerated curing using steam curing
and other techniques. In the case of steam curing using trenches or autoclaves,
this stage involves transport of moulds with the green concrete into the trench
or autoclave and taking them out after the curing and demoulding elements
cutting of protruding wires also falls in this stage. In certain cases the moulds
have to be partly removed and inserts, have to be removed after initial set The
total demoulding is done after a certain period and the components are then
allowed to be cured. All these fall in this operation.
Lifting of precast elements from the mould and transporting to the stacking
yard for further transport by trailer or rail is part of this stage.
Tests are carried out on the components individually and in combination to
ensure the adequacy of their strength.
a) Generation of steam involving storing of coal or oil necessary for
generation of steam and providing insulated steam pipe connection up
to the various technological lines.
b) Repair of machines used in the production.
9.1.6 The various accepted methods of manufacture
of precast units can be broadly classified into two
methods:
a) The 'Stand Method' where the moulds remain
stationary at places, when the various
processes involved are carried out in a cyclic
order at the same place, and
b) The 'Flow Method' where the precast unit
under consideration is in movement according
to the various processes involved in the work
which are carried out in an assembly-line
method.
The various accepted precasting methods are listed in
Table 3 with details regarding the elements that can be
manufactured by these methods.
9.2 Preparation and Storage of Materials
Storage of materials is of considerable importance in
the precasting industry, a$ a mistake in planning in this
aspect can greatly influence the economics of production.
From experience in construction, it is clear that there
will be very high percentages of loss of materials as well
as poor quality due to improper storage and transport.
So, in a precast factory where everything is produced
with special emphasis on quality, proper storage and
preservation of building materials, especially cement,
coarse and fine aggregates, is of prime importance.
Storage of materials shall be done in accordance with
Part 7 'Constructional Practices and Safety'.
9.3 Moulds
9.3.1 Moulds for the manufacture of precast elements
16
NATIONAL BUILDING CODE OF INDIA
Table 3 Precasting Methods
(Clauses 9.1.6 and 9.9.1)
SI
No.
Precasting Method
Where Used
Dimensions and
Weights
Advantages and
Remarks
(1)
(2)
(3)
(4)
(5)
i) Individual Mould Method
(precasting method which may be
easily assembled out of bottom and
sides, transportable, if necessary.
This may be either in timber or in
steel using needle or mould
vibrators and capable of taking
prestressing forces)
ii ) B attery Form Method (The
shuttering panels may be adjusted
into the form of a battery at the
required distances equal to the
thickness of the concrete member)
iii) Stack Method
iv) Tilting Mould Method (This method
is capable of being skipped
vertically using hydraulic jacks)
v) Long Line Prestressing Bed Method
vi) Extrusion Method (Long concrete
mould with constant cross-section
where concreting and vibration are
done automatically just as in hollow
code slab casting)
a) Ribbed slabs, beams,
girders, window
panels, box type units
and special elements.
b) Prestressed railway
sleepers, parts of pre-
stressed girders, etc.
Interior wall panels, shell
elements, reinforced
concrete battens, rafters,
purlins and, roof and floor
slabs
Floor and roof slab panels
Exterior wall panels
where special finishes are
required on one face or
for sandwich panel.
Double tees, ribbed slabs,
purlins, piles and beams
Roof slabs, foam concrete
wall panels and beams
cross -section where
concreting and vibration
are done automatically
just as in hollow cored
slab casting.
No limit in size and
weight. Depends on the
equipment used for
demoulding, transporting
and placing
Length :
18 m
Breadth :
3m
Mass :
5t
a) Strengthening of the cross-
section possible
b) Openings are possible in two
planes
Specially suitable for mass
production of wall panels where
shuttering cost is reduced to a
large extent and autoclave cr
trench steam curing may be
adopted by taking the steam
pipes through the shuttering
panels.
Length :
Any desired
For casting identical reinforced
length
or prestressed panels one over
Breadth :
1 to4m
the other with separating media
Mass :
5t
interposed in between.
Length :
6m
Suitable for manufacturing the
Breadth :
4m
external wall panels
Mass
5t
Length
Any desired
Ideally suited for pretension
Breadth
2m
members
Height
2m
Mass
Up to 10 1
Length : Any desired
Breadth : Less than 2 m
Height : Less than 3 m
May be used with advantage in
the case of un-reinforced blocks,
foam concrete panels
may be of steel, timber, concrete and plastic or a
combination thereof. For the design of moulds for the
various elements, special importance should be given
to easy demoulding and assembly of the various parts.
At the same time rigidity, strength and watertightness
of the mould, taking into consideration forces due to
pouring of green concrete and vibrating, are also
important.
9.3.2 Tolerances
The moulds have to be designed in such a way to take
into consideration the tolerances given in 5.
9.3.3 Slopes of the Mould Walls
For easy demoulding of the elements from the mould
with fixed sides, the required slopes have to be
maintained. Otherwise there is a possibility of the
elements getting stuck up with the mould at the time
of demoulding.
9.4 Accelerated Hardening
In most of the precasting factories, it is economical to
use faster curing methods or artificial curing methods,
which in turn will allow the elements to be demoulded
much earlier permitting early re-use of the forms. Any
of the following methods may be adopted:
a) By Heating the Aggregates and Water Before
Mixing the Concrete — By heating of the
aggregates as well as water to about 70°C to
80°C before making the concrete mix and
placing the same in the moulds, sufficiently
high earlier strengths are developed to allow
the elements to be stripped and transported.
b) Steam Curing — Steam curing may be done
under high pressure and high temperature in
an autoclave. This technique is more suited
to smaller elements. Alternatively, this could
be done using low pressure steam having
PART 6 STRUCTURAL DESIGN — SECTION 7A PREFABRICATED CONCRETE
17
temperature around 80°C. This type of curing
shall be done as specified in 9.5.2. For light
weight concrete products when steam cured
under high pressure, the drying shrinkage is
reduced considerably. Due to this reason, high
pressure steam curing in autoclave is specified
for light weight low densities ranging from
300 to 1 000 kg/m 3 . For normal heavy
concretes as well as light weight concretes of
higher densities, low pressure steam curing
may be desirable as it does not involve using
high pressures and temperatures requiring
high investment in an autoclave (see
also 9.5.2).
c) Steam Injection During Mixing of Concrete
— In this method low pressure saturated
steam is injected into the mixer while the
aggregates are being mixed. This enables the
heating up of concrete to approximately 60°C.
Such a concrete after being placed in the
moulds attains high early strength.
d) Heated Air Method — In this method, the
concrete elements are kept in contact with hot
air with a relative humidity not less than 80
percent. This method is specially useful for
light weight concrete products using porous
coarse aggregates.
e) Hot Water Method — In this method, the
concrete elements are kept in a bath of hot
water around 50°C to 80°C. The general
principles of this type of curing are not much
different from steam curing.
f) Electrical Method — The passage of current
through the concrete panels generates heat
through its electro-resistivity and accelerates
curing. In this method, the concrete is heated
up by an alternating current ranging from 50
volts for a plastic concrete and gradually
increasing to 230 V for the set concrete. This
method is normally used for massive concrete
products.
9.4.1 After the accelerated hardening of the above
products by any of the above accepted methods, the
elements shall be cured further by normal curing
methods to attain full final strength.
9.4.2 Accelerated hardening may also be achieved by
the following techniques:
a) Construction Chemicals — Suitable
construction chemicals may be used.
b) Consolidation by Spinning — Such a method
is generally used in the centrifugal moulding
of pipes and such units. The spinning motion
removes excess water, effects consolidation
and permits earlier demoulding.
c) Pressed Concrete — This method is suitable
for fabrication of small or large products at
high speed of production. A 100-200 tonnes
press compresses the wet concrete in rigid
moulds and expels water. Early handling arid
a dense wear resistant concrete is obtained.
d) Vacuum Treatment — This method removes
the surplus air and water from the newly
placed concrete as in slabs and similar
elements. A suction up to about 70 percent of
an atmosphere is applied for 20 to 30 minutes
per centimetre thickness of the units.
e) Consolidation by Shock — This method is
suitable for small concrete units dropped
repeatedly from a height in strong moulds.
The number of shocks required to remove
excess water and air may vary from 6 to 20
and the height of lift may be up to as much as
half the depth of the mould.
9.4.3 After the accelerated curing of the above
products by any of the above accepted methods, the
elements shall be cured further by normal curing
methods to attain full final strength.
9.5 Curing
9.5.1 The curing of the prefabricated elements can be
effected by the normal methods of curing by sprinkling
water and keeping the elements moist. This can also
be done in the case of smaller elements by immersing
them in a specially made water tanks.
9.5.2 Steam Curing
9.5.2.1 The steam curing of concrete products shall
take place under tarpaulin in tents, under hoods, under
chambers, in tunnels or in special autoclaves. The
steam shall have a uniform quality throughout the
length of the member. The precast elements shall be
so stacked, with sufficient clearance between each
other and the bounding enclosure, so as to allow proper
circulation of steam.
Before the concrete products are subjected to any
accelerated method of curing, the cement to be used
shall be tested in accordance with accepted standards
(see Part 5 Building Materials) especially for
soundness, setting time and suitability for steam curing.
In the case of elements manufactured by accelerated
curing methods, concrete admixtures to reduce the
water content can be allowed to be used. The normal
aeration agents used to increase the workability of
concrete should not be allowed to be used. Use of
calcium chloride should be avoided for reinforced
concrete elements.
9.5.2.2 The surrounding walls, the top cover and the
18
NATIONAL BUILDING CODE OF INDIA
floor of steam curing chamber or tunnel or hood
shall be so designed as not to allow more than
1 kcal/m 2 /h/°C.
9.5.2.3 The inside face of the steam curing chamber,
tunnel or hood shall have a damp-proof layer to
maintain the humidity of steam. Moreover, proper
slope shall be given to the floor and the roof to allow
the condensed water to be easily drained away. At first,
when steam is let into the curing chambers, the air
inside shall be allowed to go out through openings
provided in the hoods or side walls which shall be
closed soon after moist steam is seen jetting out.
9.5.2.4 It is preferable to let in steam at the top of the
chamber through perforated pipelines to allow uniform
entry of steam throughout the chamber.
9.5.2.5 The fresh concrete in the moulds should be
allowed to get the initial set before allowing the
concrete to come into contact with steam. The regular
heating up of fresh concrete product from about 20°C
to 35 °C should start only after a waiting period ranging
from 2 to 5 h depending on the setting time of cement
used. It may be further noted that steam can be let
in earlier than this waiting period provided the
temperature of the concrete product does not rise
beyond 35 °C within this waiting period.
9.5.2.6 The second stage in steam curing process is to
heat up the concrete elements, moulds and the
surroundings in the chamber:
a) In the low pressure steam curing the airspace
around the member is heated up to a
temperature of 75°C to 80°C at a gradual rate,
usually not faster than 30°C per hour.
This process takes around 1 h to lVih
depending upon outside temperature.
b) In the case of curing under high pressure
steam in autoclaves, the temperature and
pressure are gradually built up during a period
of about 4 h.
9.5.2.7 The third stage of steam curing is to maintain
the uniform temperature and pressure for a duration
depending upon thickness of the section. This may vary
from 3 h to 5Vi h in the case of low pressure steam
curing and 4 h to 7 h in the case of high pressure steam
curing.
9.5.2.8 The fourth stage of steam curing is the gradual
cooling down of concrete products and surroundings
in the chamber and normalization of the pressure to
bring it at par with outside air. The maximum cooling
rate, which is dependent on the thickness of the
member, should normally not exceed 30°C per hour.
9.5.3 In all these cases, the difference between the
temperature of the concrete product and the outside
temperature should not be more than 60°C for
concretes up to M 30 and 75°C for concretes greater
than M 45. In the case of light weight concrete, the
difference in temperature should not be more than 60°C
for concretes less than M 25. For concretes greater
than M 50, the temperature differences can go up
to 75°C.
9.6 Stacking During Transport and Storage
Every precaution shall be taken against overstress or
damage, by the provision of suitable packings at agreed
points of support. Particular attention is directed to the
inherent dangers of breakage and damage caused by
supporting other than at two positions, and also by the
careless placing of packings (for example, not
vertically one above the other). Ribs, corners and
intricate projections from solid section should be
adequately protected. Packing pieces shall not
discolour, disfigure or otherwise permanently cause
mark on units or members. Stacking shall be arranged
or the precast units should be protected, so as to prevent
the accumulation of trapped water or rubbish, and if
necessary to reduce the risk of efflorescence.
9.6.1 The following points shall be kept in view during
stacking:
a) Care should be taken to ensure that the flat
elements are stacked with right side up. For
identification, top surfaces should be clearly
marked.
b) Stacking should be done on a hard and
suitable ground to avoid any sinking of
support when elements are stacked.
c) In case of horizontal stacking, packing
materials shall be at specified locations and
shall be exactly one over the other to avoid
cantilever stress in panels.
d) Components — should be packed in a uniform
way to avoid any undue projection of
elements in the stack which normally is a
source of accident.
9.7 Handling Arrangements
9.7.1 Lifting and handling positions shall be clearly
defined particularly where these sections are critical.
Where necessary special facilities, such as bolt holes
or projecting loops, shall be provided in the units and
full instructions supplied for handling.
9.7.2 For precast prestressed concrete members, the
residual prestress at the age of particular operation
of handling and erection shall be considered in
conjunction with any stresses caused by the handling
or erection of member. The compressive stress thus
computed shall not exceed 50 percent of the cube
strength of the concrete at the time of handling and
PART 6 STRUCTURAL DESIGN — SECTION 7A PREFABRICATED CONCRETE
19
erection. Tensile stresses up to a limit of 50 percent
above those specified in Part 6 'Structural Design,
Section 5 Concrete' shall be permissible.
9.8 Identification and Marking
All precast units shall bear an indelible identification,
location and orientation marks as and where necessary.
The date of manufacture shall also be marked on the
units.
9.8.1 The identification markings on the drawings
shall be the same as that indicated in the manufacturer's
literature and shall be shown in a table on the setting
schedule together with the length, type, size of the unit
and the sizes and arrangement of all reinforcement.
9.9 Transport
Transport of precast elements inside the factory and to
the site of erection is of considerable importance not
only from the point of view of economy but also from
the point of view of design and efficient management.
Transport of precast elements must be carried out with
extreme care to avoid any jerk and distress in elements
and handled as far as possible in the same orientation
as it is to be placed in final position.
9.9.1 Transport Inside the Factory
Transport of precast elements moulded inside the
factory depends on the method of production, selected
for the manufacture as given in Table 3.
9.9.2 Transport from Stacking Yard Inside the Factory
to the Site of Erection
Transport of precast concrete elements from the factory
to the site of erection should be planned in such a way
so as to be in conformity with the traffic rules and
regulations as stipulated by the Authorities. The size
of the elements is often restricted by the availability of
suitable transport equipment, such as tractor-cum-
trailers, to suit the load and dimensions of the member
in addition to the opening dimensions under the bridge
and load carrying capacity while transporting the
elements over the bridge.
9.9.2.1 While transporting elements in various
systems, that is, wagons, trucks, bullock carts, care
should be taken to avoid excessive cantilever actions
and desired supports are maintained. Special care
should be taken at location of sharp bends and on
uneven or slushy roads to avoid undesirable stresses
in elements.
9.9.2.2 Before loading the elements in the transporting
media, care should be taken to ensure that the base
packing for supporting the elements are located at
specified positions only. Subsequent packings must be
kept strictly one over the other.
9.10 Erection
In the 'erection of precast elements', all the following
items of work are meant to be included:
a) Slinging of the precast element;
b) Tying up of erection ropes connecting to the
erection hooks;
c) Cleaning of the elements and the site of
erection;
d) Cleaning of the steel inserts before
incorporation in the joints, lifting up of the
elements, setting them down into the correct
envisaged position;
e) Adjustment to get the stipulated level, line and
plumb;
f) Welding of cleats;
g) Changing of the erection tackles;
h) Putting up and removing of the necessary
scaffolding or supports;
j) Welding of the inserts, laying of reinforcements
in joints and grouting the joints; and
k) Finishing the joints to bring the whole work
to a workmanlike finished product.
9.10.1 In view of the fact that the erection work in
various construction jobs using prefabricated concrete
elements differs from place to place depending on the
site conditions, safety precautions in the work are of
utmost importance. Hence only those skilled foremen,
trained workers and fitters who have been properly
instructed about the safety precautions to be taken should
be employed on the job. For additional information, see
Part 7 'Constructional Practices and Safety'.
9.10.2 Transport of people, workers or visitors, by
using cranes and hoists should be strictly prohibited
on an erection site.
9.10.3 In the case of tower rail mounted cranes running
on rails, the track shall not have a slope more than
0.2 percent in the longitudinal direction. In the transverse
direction the rails shall lie in a horizontal plane.
9.10.4 The track of the crane should be daily checked
to see that all fish plates an$ bolts connecting them to
the sleepers are in place and in good condition.
9.10.5 The operation of all equipment used for
handling and erection shall follow the operations
manual provided by the manufacturer. All safety
precautions shall be taken in the operations of handling
and erection.
10 EQUIPMENT
10.1 General
The equipment used in the precast concrete industry/
20
NATIONAL BUILDING CODE OF INDIA
construction may be classified into the following
categories:
a) Machinery required for quarrying of coarse
and fine aggregates",
b) Conveying equipment, such as, belt conveyors,
chain conveyors, screw conveyors, bucket
elevators, hoists, etc;
c) Concrete mixing machines;
d) Concrete vibrating machines;
e) Erection equipment, such as, cranes, derricks,
hoists, chain pulley blocks, etc;
f) Transport machinery, such as, tractor-cum-
trailers, dumpers, lorries, locomotives, motor
boats and rarely even helicopters;
g) Workshop machinery for making and repairing
steel and timber moulds;
h) Bar straightening, bending and welding
machines to make reinforcement cages;
j) Minor tools and tackles, such as, wheel
barrows, concrete buckets, etc; and
k) Steam generation plant for accelerated curing.
In addition to the above, pumps and soil compacting
machinery are required at the building site for the
execution of civil engineering projects involving
prefabricated components.
Each of the above groups may further be classified
into various categories of machines and further to
various other types depending on the source of power
and capacity.
10.2 Mechanization of the Construction and
Erection Processes
The various processes can be mechanized as in any
other industry for attaining the advantages of mass
production of identical elements which in turn will
increase productivity and reduce the cost of production
in the long run, at the same time guaranteeing quality
for the end-product. On the basis of the degree of
mechanization used, the various precasting factories
can be divided into three categories:
a) With simple mechanization,
b) With partial mechanization, and
c) With complex mechanization leading to
automation.
10.2.1 In simple mechanization, simple mechanically
operated implements are used to reduce the manual
labour and increase the speed.
10.2.2 In partial mechanization, the manual work is
more or less eliminated in the part of a process. For
example, the batching plant for mixing concrete, hoists
to lift materials to a great height and bagger and
bulldozer to do earthwork come under this category.
10.2.3 In the case of complex mechanization leading
to automation, a number of processes leading to the
end-product are all mechanized to a large extent
(without or with a little manual or human element
involved). This type of mechanization reduces manual
work to the absolute minimum and guarantee the mass
production at a very fast rate and minimum cost.
10.2.4 The equipment shall conform to accepted
standards as listed in Part 7 'Constructional Practices
and Safety'.
11 PREFABRICATED STRUCTURAL UNITS
11.1 For the design and construction of composite
structures made up of prefabricated structural units and
cast in-situ concrete, reference may be made to good
practice [6-7 A(3)].
11.2 For design and construction of precast reinforced
and prestressed concrete triangulated trusses reference
may be made to good practice [6-7 A(4)].
11.3 For design and construction of floors and roofs
using various precast units, reference may be made to
good practice [6-7A(5)J.
11.4 For construction with large panel prefabricates,
reference may be made to good practice [6-7 A(6)].
11.5 For construction of floors and roofs with joists
and filler blocks, reference may be made to good
practice [6-7 A(7)].
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and 'accepted standards'
in the fulfilment of the requirements of the Code. The
latest version of a standard shall be adopted at the time
of enforcement of the Code. The standards listed may
be used by the Authority as a guide in conformance
with the requirements of the referred clauses in the
Code.
In the following list the number appearing in the first
column within parentheses indicates the number of the
reference in this Part/Section.
IS No. Title
(1) 2185 Specification for concrete
masonry units:
(Part 1) : 1979 Hollow and solid concrete
blocks (second revision)
PART 6 STRUCTURAL DESIGN — SECTION 7A PREFABRICATED CONCRETE
21
IS No.
(Part 2) : 1983
(Part 3): 1984
3201 : 1988
6072: 1971
6073 : 1971
9893 : 1981
10297 : 1982
10505 : 1983
11447:1985
12440 : 1988
13990: 1994
14143 : 1994
14201 : 1994
14241 : 1994
Title
Hollow and solid light weight
concrete blocks {first revision)
Autoclaved cellular aerated
concrete blocks (first revision)
Criteria for design and
construction of precast trusses
and purlins (first revision)
Specification for autoclaved
reinforced cellular concrete wall
slabs
Specification for autoclaved
reinforced cellular concrete
floor and roof slabs
Specification for precast concrete
blocks for lintels and sills
Code of practice for design and
construction of floors and
roofs using precast reinforced/
prestressed concrete ribbed or
cored slab unit
Code of practice for construction
of floors and roofs using precast
concrete waffle units
Code of practice for construction
with large panel prefabricates
Specification for precast
concrete stone masonry blocks
Specification for precast
reinforced concrete planks and
joists for flooring and roofing
Specification for prefabricated
brick panel and partially precast
concrete joist for flooring and
roofing
Specification for precast
reinforced concrete channel unit
for construction of floors and
roofs
Specification for precast
L-Panel units for roofing
IS No.
(2) 4905 : 1968
(3) 3935 : 1966
(4) 3201 : 1988
(5) 6332 : 1984
10297 : 1982
10505 : 1983
13994:1994
14142 : 1994
14215 : 1994
14242: 1994
(6) 11447:1985
(7) 6061
(Parti) :1971
(Part 2) : 1981
Title
Methods for random sampling
Code of practice for composite
construction
Criteria for design and
construction of precast trusses
and purlins (first revision)
Code of practice for construction
of floor and roofs using precast
doubly-curved shell units (first
revision)
Code of practice for design and
construction of floors and
roofs using precast reinforced/
prestressed concrete ribbed or
cored slab units
Code of practice for construction
of floors and roofs using precast
reinforced concrete waffle units
Code of practice for design and
construction of floor and roof
with precast reinforced concrete
planks and RC joists
Code of practice for design and
construction of floors and roofs
with prefabricated brick panel
Code of practice for construction
of floor and roof with RC
channel units
Code of practice for design and
construction of roof with
L-Panel units
Code of practice for construction
with large panel prefabricates
Code of practice for construction
of floor and roof with joists and
hollow filler blocks:
With hollow concrete filler
blocks
With hollow clay filler blocks
(first revision)
22
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 7 Prefabrication, Systems Building and
Mixed/Composite Construction:
7B Systems Building and Mixed/Composite Construction
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 MATERIALS, PLANS AND SPECIFICATIONS
4 MODULAR CO-ORDINATION, ARCHITECTURAL TREATMENT AND
FINISHES
5 COMPONENTS
6 FORMWORK SYSTEMS
7 SYSTEM AND STRUCTURAL SCHEMES
8 JOINTS
9 TESTS FOR COMPONENTS/STRUCTURES
10 CONSTRUCTIONAL ASPECTS
11 EQUIPMENT
12 PREFABRICATED STRUCTURAL UNITS
ANNEX A CONSTRUCTION PRACTICE FOR DECKING
ANNEX B CONSTRUCTION PRACTICE FOR CONCRETING ON DECKING
LIST OF STANDARDS
5
5
6
6
6
6
6
8
8
8
8
8
8
10
11
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
Systems building and mixed/composite construction is an upcoming field as far as its development and use in the
country is concerned. Two aspects specifically to be borne in mind are the system to be adopted for the different
categories of buildings and the sizes of their components. Here the principle of modular co-ordination is of value
and its use is recommended.
This section was first published in 1970 and was subsequently revised in 1983.
In this second revision, this section, earlier named as Prefabrication and Systems Building has been renamed and
restructured as follows:
Section 7 Prefabrication, Systems Buildings and Mixed/Composite Construction
7A Prefabricated Concrete
7B Systems Buildings and Mixed/Composite Construction
This sub-section covers systems building and mixed/composite construction, while such systems approach using
predominantly concrete as material for components is being dealt with in sub-section 7A.
In this sub-section, an attempt has been made to prescribe general requirements applicable to all valid existing
systems and mixed/composite constructions as also to accommodate any new system introduced in the country
in future.
All standards cross referred to in the main text of this sub-section, are subject to revision. The parties to agreement
based on this sub-section are encouraged to investigate the possibility of applying the most recent editions of the
standards.
PART 6 STRUCTURAL DESIGN — SECTION 7B SYSTEMS BUILDING AND MIXED/COMPOSITE CONSTRUCTION
NATIONAL BUILDING CODE OF INDIA
PART 6 STRUCTURAL DESIGN
Section 7 Prefabrication, Systems Building and
Mixed/Composite Construction:
7B Systems Building and Mixed/Composite Construction
1 SCOPE
This sub-section covers recommendations regarding
modular planning, component sizes, joints, manufacture,
storage, transport and erection of prefabricated
elements for use in buildings and such related
requirements for systems building and mixed/
composite construction.
2 TERMINOLOGY
2.1 For the purpose of this sub-section, the following
definitions shall apply.
2.1.1 Authority Having Jurisdiction — The Authority
which has been created by a statute and which, for the
purpose of administering the Code/Part, may authorize
a committee or an official or an agency to act on its
behalf; hereinafter called the 'Authority'.
2.1.2 Basic Module — The fundamental module used
in modular co-ordination, the size of which is selected
for general application to building and its components.
NOTE — The value of the basic module has been chosen as
100 mm for the maximum flexibility and convenience. The
symbol for the basic module is M.
2.1.3 Cellular Concrete — The material consisting of
an inorganic binder (such as, lime or cement or both)
in combination with a finely ground material
containing siliceous acid (such as sand), gas generating
material (for example, aluminium powder), water and
harmless additives (optional); and steam cured under
pressure in autoclaves.
2.1.4 Components — A building product formed as a
distinct unit having specified sizes in three dimensions.
2. 1 .5 Composite/Mixed Construction — Construction
involving two or more components, such as,
prefabricated structural units of steel, prestressed
concrete or reinforced concrete and cast in-situ
concrete, timber, masonry in brickwork and blockwork,
glass and glazing connected together in such a manner
that they act integrally.
2.1.6 Increments — Difference between two homologous
dimensions of components of successive sizes.
2.1.7 Module -
co-ordination.
A unit of size used in dimensional
2.1.8 Modular Co-ordination — Dimensional
co-ordination employing the basic module or a multi-
module.
NOTE — The purposes of modular co-ordination are:
a) to reduce the variety of component sizes produced, and
b) to allow the building designer greater flexibility in the
arrangement of components.
2.1.9 Modular Grid — A rectangular coordinate
reference system in which the distance between
consecutive lines is the basic module or a multi-
module. This multi-module may differ for each of the
three orthogonal dimensions of the grid, two in plan
and one in vertical direction.
2.1.10 Multi-module — A module whose size is a
selected multiple of the basic module.
2.1.11 Prefabricate — To fabricate components or
assembled units prior to erection or installation in a
building.
2.1.12 Prefabricated Building — The partly/fully
assembled and erected building, of which the structural
parts consist of prefabricated individual units or
assemblies using ordinary or controlled materials,
including service facilities; and in which the service
equipment may be either prefabricated or constructed
in-situ.
2.1.13 Sandwich Panels — Panels made by sandwiching
a layer of insulation material between two outer layers
of hard durable materials like steel, dense concrete,
plastic, cement based sheet, ceramic, etc. The hard
coverings on two outer faces may be of same or
different materials; the three layers being bonded with
each other to behave as a composite panel.
2.1.14 Self-Compacting Concrete — Concrete that is
able to flow under its own weight and completely fill
the voids within the formwork, even in the presence
of dense reinforcement without any vibration, whilst
maintaining homogeneity without segregation.
2.1.15 Shear Connectors — Structural elements, such
as anchors, studs, channels and spirals, intended to
transmit the shear between the prefabricated member
and the cast in-situ concrete and also to prevent
separation at the interface.
2.1.16 System — The method of construction
of buildings with certain order and discipline
and repetitive operations using the prefabricated
components, tunnel form or engineered shuttering,
where the work is organized and follows a defined
procedure.
PART 6 STRUCTURAL DESIGN — SECTION 7B SYSTEMS BUILDING AND MIXED/COMPOSITE CONSTRUCTION
2.1.17 Unit — Building material formed as a simple
article with all three dimensions specified, complete
in itself but intended to be part of a compound unit or
complete building. Examples are brick, block, tile,
etc.
3 MATERIALS, PLANS AND SPECIFICATIONS
3.1 Materials
3.1.1 See Part 6 'Structural Design, Sub-section 7A
Prefabricated Concrete', regarding materials and the
characteristics to be considered in their selection.
3.1.2 The materials used in prefabricated components
may be many and the modern trend is to use concrete,
steel, treated wood, aluminium, cellular concrete, light
weight concrete, ceramic products, etc. However, this
section pertains to mixed/composite construction.
3.2 Plans and Specifications
See Part 6 'Structural Design, Sub-section 7A
Prefabricated Concrete'.
4 MODULAR CO-ORDINATION,
ARCHITECTURAL TREATMENT AND
FINISHES
4.1 Modular Co-ordination
See Part 6 'Structural Design, Sub-section 7A
Prefabricated Concrete'.
4.2 Architectural Treatment and Finishes
See Part 6 'Structural Design, Sub-section 7A
Prefabricated Concrete'.
5 COMPONENTS
5.1 The preferred dimensions of precast elements used
and their casting tolerances shall be in accordance with
Part 6 'Structural Design, Sub-section 7 A Prefabricated
Concrete' .
5.2 The permissible tolerances of timber used shall
be in accordance with Part 6 'Structural Design, Sub-
section 3 A Timber' .
5.3 For permissible tolerances of steel and masonry,
reference may be made to relevant Indian Standards.
6 FORMWORK SYSTEMS
The formwork systems which are utilized in buildings
shall be as given in 6.1 to 6.5.
6.1 Tunnel Form
This is a system which casts walls and slab together
like a portal in a single pour. Facade walls are precast
or of block masonry to enable removal of tunnel form.
All components are made up of steel. This produces
very rapid construction. Accelerated curing if required
is possible enabling early stripping of formwork.
6.2 Slipform
Slipform is a continuously moving form at such a speed
that the concrete when exposed has already achieved
enough strength to support the vertical pressure from
concrete still in the form as well as to withstand
nominal lateral forces. Slipform may be classified as
straight slipform, tapering slipform and slipform for
special applications. Construction of lift cores and
stairwell using slipform technique comes under special
applications because of their complex sizes, shapes and
loads to be lifted alongwith the slipform like walkway
truss, etc, which is essential for construction. This
system uses hydraulic jacks avoiding crane for lifting
of assembly during construction operation. This system
facilitates rapid construction and continual casting,
creating a monolithic structure thereby avoiding
construction joints.
6.3 Aluminium Formwork
This system of formwork uses aluminium, which is
light and rust free material, in both sheathing and
framework. It may be used for a broad range of
applications from wall to slab construction panels to
more complicated structures involving bay windows,
stairs and hoods. Every component is light enough to
be handled easily thereby minimizing the need for
heavy lifting equipment.
6.4 Large Panel Shuttering System
This is a system, which gives an advantage of
combining speed and quality of construction. The
vertical load carrying members are made of steel
whereas the horizontal members are of plywood
inserted into two wooden beams thereby forming a web
flange. All the formwork and support systems shall be
designed for the loads coming during the actual
execution stage.
6.5 Other/New Systems
Any other/new system may be used for systems
building after due examination and approval by the
Authority.
7 SYSTEM AND STRUCTURAL SCHEMES
7.1 Several schemes are possible, with certain
constraints, using the same set of components. The
degree of flexibility varies from system to system.
However, in all the systems there is a certain order
and discipline.
7.2 The following aspects, among others, are to be
considered in devising a system:
NATIONAL BUILDING CODE OF INDIA
a) Effective utilization of spaces;
b) Straight and simple walling scheme;
c) Limited sizes and numbers of components;
d) Limited opening in bearing walls;
e) Regulated locations of partitions;
f) Standardized service and stair units;
g) Limited sizes of doors and windows with
regulated positions;
h) Structural clarity and efficiency;
j) Suitability for adoption in low and high rise
building;
k) Ease of manufacturing, storing and transporting;
m) Speed and ease of erection; and
n) Simple jointing system.
7.3 Systems for Mixed/Composite Construction
The system of mixed/composite construction depends
on the extent of the use of prefabricated components,
their materials, sizes and the technique adopted for their
manufacture and use in building.
7.3.1 Combinations of System Components for Mixed/
Composite Construction
The following combinations may be used in mixed/
composite construction:
a) Structural steel work and timber roofs on
precast frames.
b) Precast floors onto steel and concrete beams,
and masonry walls.
c) Profiled metal decking on precast beams.
d) Precast frames onto cast in- situ foundations,
retaining walls, etc.
e) Precast frames stabilized by masonry walls,
steel bracing, etc.
f) Precast cladding in steel or cast in-situ frames
and vice versa.
g) Glass curtain walling, stone cladding or metal
sheeting onto precast concrete frames, etc.
h) Reinforced concrete and structural steel as
composite columns and beams.
7.3.1.1 Precast concrete may be combined with cast
in-situ concrete, often termed hybrid construction. Cast
in-situ is mostly used to form homogenous connections
between precast elements and provide a structural
topping for horizontal diaphragm action. In other cases
it is used to form the foundations and sub-structure to
the building.
7.3.1.2 Structural steelwork is largely used in long
span prestressed concrete floors supported on rolled
and prefabricated steel beams and also as steel roof
trusses supported on concrete columns.
7.3.1.3 Timber may be used as long span glue-
laminated beams and rafters, with precast concrete.
Precast floors may be used in timber frame
construction. Similarly, timber frames with precast
elements shall be used as a building system.
7.3.1.4 Brick and block masonry may be combined
with precast concrete structures and floors. The' most
common combinations is to use prestressed floors on
load bearing walls.
7.4 Design Considerations
The mixed/composite structures shall be analyzed
appropriately and the joints in them designed to take
the forces of an equivalent discrete system. Resistance
to horizontal loading shall be provided by placing
beams, walls and bracings in two directions at right
angles or otherwise. The individual components shall
be designed, taking into consideration appropriate end
conditions and loads at various stages of construction.
The components of the structure shall be designed for
loads in accordance with Part 6 'Structural Design,
Section 1 Loads, Forces and Effects'. In addition,
members shall be designed for handling, erection and
impact loads that may be expected during handling
and erection.
7.4.1 For mixed and composite construction the
following points shall be considered:
a) Positions of stability cores, walls, bracing,
etc. — In high rise buildings the most popular
method is a cast in-situ core constructed
several storeys ahead of the framework. In
medium height buildings this may be precast
concrete or brick infill, steel cross bracing or
precast concrete diagonal bracing.
b) Maturity of connections — This may be
decisive for or alter planned site progress
unless it is properly managed. Cast in-situ
grouted joints need a few days of temporary
propping unless combined mechanical
connections are also used.
c) As a consequence of the above, the need to
design some of the key components to achieve
temporary stability.
d) The availability and/or positioning of
equipments to transport and erect components
— The size and weight of the various
components shall be organized to make
optimum use of crane capacity, for example,
the lightest units farthest from the operating
zone.
e) Erection safety and speed of construction,
with attention to cast in-situ concreting
sequences — This is particularly important
PART 6 STRUCTURAL DESIGN — SECTION 7B SYSTEMS BUILDING AND MIXED/COMPOSITE CONSTRUCTION
where fixing gangs are unaccustomed to
working with different materials.
f) Tolerances for economical construction —
This is particularly important where different
manufacturers are producing components in
different materials.
7.4.2 Other design considerations and safety
requirements against progressive collapse shall be in
accordance with Part 6 'Structural Design, Sub-section
7 A Prefabricated Concrete'.
8 JOINTS
Design of joints shall be in accordance with Part 6
'Structural Design, Sub-section 7A Prefabricated
Concrete' .
9 TESTS FOR COMPONENTS/STRUCTURES
Sampling procedure, testing on individual components
and load testing of structure shall be in accordance with
Part 6 'Structural Design, Sub-section 7A Prefabricated
Concrete' .
10 CONSTRUCTIONAL ASPECTS
10.1 Manufacture, Storage, Transport and Erection
of Precast Elements
The requirements relating to manufacture, storage,
transport and erection of precast concrete elements
shall be in accordance with Part 6 'Structural Design,
Sub-section 7 A Prefabricated Concrete'.
10.2 Decking
Constructional practices relating to decking shall be
as given in Annex A.
10.3 Concreting on Decking
Concreting on decking shall be carried out in
accordance with Annex B.
11 EQUIPMENT
The requirements relating to equipment used in the
precast concrete construction shall be in accordance
with Part 6 'Structural Design, Sub-section 7A
Prefabricated Concrete*.
12 PREFABRICATED STRUCTURALUNITS
12.1 For the design and construction of composite
structures made up of prefabricated structural units and
cast in-situ concrete, reference may be made to good
practice [6-7B(l)].
12.2 For design and construction of precast reinforced
and prestressed concrete triangulated trusses reference
may be made to good practice [6-7B(2)].
12.3 For design and construction of floors and roofs
using various precast units, reference may be made to
good practice [6-7B(3)].
12.4 For construction with large panel prefabricates,
reference may be made to good practice [6-7B(4)].
12.5 For construction of floors and roofs with joists
and filler blocks reference may be made to good
practice [6-7B(5)].
ANNEX A
{Clause 10.2)
CONSTRUCTION PRACTICE FOR DECKING
A-l RECEIVING, STORING AND LIFTING
DECKING
A-Ll Receiving Decking
Decking is packed by the manufacturer into bundles
of up to 24 sheets, and the sheets are normally secured
with metal banding. Each bundle may be up to 1 m
wide (the width of a single sheet) by 750 mm deep,
and may weigh up to 2.5 t, depending on sheet length
(average mass of sheet being about 1.5 t). Loads
are normally delivered by articulated vehicles
approximately 16 m long with a maximum gross mass
of up to 40 t, and a turning circle of approximately
19 m. It shall be ensured that there is suitable access
and appropriate standing and off-loading areas.
Each bundle will be given an identification tag by the
manufacturer. The information on each tag shall be
checked immediately upon arrival, to prevent incorrect
sheets being used, or unnecessary delays if changes
are necessary. In particular, the stated sheet thickness
shall be checked against the requirement specified on
the drawings, and a visual inspection shall be made to
ensure that there is no damage.
The bundles shall be lifted from the vehicle. Bundles
shall never be off-loaded by tipping, dragging,
dropping or other improvized means.
A-1.2 Storing Decking
The decking shall not be delivered more than one
month before its anticipated use, as it may be vulnerable
to abuse and damage if stored for longer periods on
site. If it is not for immediate use, the decking shall be
NATIONAL BUILDING CODE OF INDIA
stored on the steel frame. If this is not possible, it shall
be located in an area where it will not be contaminated
by site traffic, and placed on bearers, which provide a
gentle slope to the bundle. This will allow any
condensation or rain to drain and a free flow of air
around the bundle. Bundles shall not be stacked more
than 4 m high, and no other materials shall be stored
on top of them. Bearers shall be placed between
bundles, and positioned to prevent bending of the
sheets.
A-1.3 Lifting and Positioning the Decking
The support steelwork shall be prepared to receive the
decking before lifting the bundles onto it. The top
surface of the underlying beams shall be reasonably
clean. When through-deck welding of shear studs is
specified, the tops of the flanges shall be free of primer,
paint and galvanising.
The identification tags shall be used to ensure that
bundles are positioned on the frame at the correct floor
level, and in the nominated bay shown on the deck
layout drawing. The bundles shall be positioned such
that the interlocking side laps are on the same side.
This will enable the decking to be laid progressively
without the need to turn the sheets. The bundles shall
also be positioned in the correct span orientation, and
not at 90° to it. Care shall be taken to ensure that the
bundles are not upside down, particularly with
trapezoidal profiles. For most trapezoidal decking
profiles, the embossments shall be oriented so that they
project upwards.
Care is needed when lifting the decking bundles;
protected chain slings are recommended for the same.
Unprotected chain slings can damage the bundle
during lifting. When synthetic slings are used there
is a risk of the severing them on the edges of the
decking sheets.
If timber packers are used, they shall be secured to the
bundle before lifting so that when the slings are
released they do not fall to the ground (with potentially
disastrous results). Bundles shall never be lifted using
metal banding.
A-2 DECK INSTALLATION
A-2.1 Placement of Decking
Breaking open the bundles and installing the decking
shall be done only when all the sheets can be positioned
and secured. The decking layout drawing shall also be
checked to ensure that any temporary support that need
to be in position prior to deck laying, is in place.
Access for installation may normally be achieved using
ladders connected to the steel frame. Once the laying
out the sheets is started by erectors, they shall create
working platform by securely fixing the decking as
they progress.
The laying of sheets shall begin at the locations
indicated on the decking layout drawings. These would
normally be at the corner of the building at each level,
to reduce the number of 'leading edges', that is
unprotected edges where the decking is being laid.
When the bundles have been properly positioned, as
provided above, there shall be no need to turn the sheets
manually, and there shall be no doubt which way up
the sheet shall be fixed.
Individual sheets shall be slid into place and, where
possible, fixed to the steelwork before moving onto
the next sheet. This will minimize the risk of an
accident occurring as a result of movement of a sheet
when it is being used as a platform. However, for
setting-out purposes, it may be necessary to lay out an
entire bay using a minimum number of temporary
fixings before fully securing the sheets later.
Sheets shall be positioned to provide a minimum
bearing of 50 mm on the steel support beams. The ends
of adjacent sheets shall be butted together. A gap of
up to 5 mm is generally considered not to allow
excessive seepage, but, if necessary, the ends of the
sheets may be taped together. When end gaps are
greater than 5 mm, it is normally sufficient to seal them
with an expanding foam filler. The longitudinal edges
shall be overlapped, to minimize concrete seepage
along the seams. Although not normally required, seam
fixings may be necessary in some circumstances.
Sheets projecting freely more than 600 mm shall be
avoided.
If necessary, sheets shall be cut using a grinder or a
nibbler. However, field cutting shall be kept to a
minimum and shall only be necessary where a column
or other obstruction interrupts the decking. Gaps
adjacent to the webs of columns shall be filled in with
off-cuts or thin strips of steel. Decking sheets shown
as continuous on the decking layout drawing shall
never be cut into more than one length. Also, sheets
shall never be severed at the location of a temporary
support, and the decking shall never be fastened to a
temporary support.
As the work progresses, scraps and off-cuts shall be
disposed of in a skip placed alongside the appropriate
level of working. The skip shall be positioned carefully
over a support beam to avoid overloading the decking.
If a skip is not available, scraps shall be gathered for
collection as soon as is possible. Partially used bundles
shall be secured, to avoid individual sheets moving in
strong winds.
A-2.2 Fixing of Decking
Decking sheets shall be fixed to the top of the
PART 6 STRUCTURAL DESIGN — SECTION 7B SYSTEMS BUILDING AND MIXED/COMPOSITE CONSTRUCTION
supporting structure. All fixings shall be made through
the troughs in the decking. Fixings shall be at
approximately 300 mm centres (or in every trough)
along the end supports, and at 600 mm centres (or in
alternate troughs) along the internal supports. As an
absolute minimum, each sheet shall be connected at
least twice to each permanent support. The number
and placement of fasteners will normally be given on
the decking layout drawing. Fixings shall not be made
to temporary supports.
The fixings, together with 'through-deck' welded studs
(if present) normally provide lateral restraint to the
beams during the construction stages.
ANNEX B
(Clause 10.3)
CONSTRUCTION PRACTICE FOR CONCRETING ON DECKING
B-l PLACING CONCRETE
B-l.l Preparation
Prior to beginning work on the decking, guardrails shall
be in position at all perimeters, internal edges and
voids. The positions of any props (and back props)
shall be checked against the details shown on the
decking layout drawings to ensure that adequate
support has been provided,
B-1.2 Cleaning the Decking
The surface of the decking shall be reasonably free of
dirt, oil, etc prior to concreting.
B-1.3 Construction Joints
Although there is no technical limitation to the area
that may be concreted, the usual pour area is up to
1 000 m 2 /day. Where the limits of the pour do not
coincide with permanent slab edges, construction joints
are used to define the extent of the pour.
The locations and details of the construction joints may
have an effect on the cracking. The layout and details
of the joints shall be determined by the structural
designer. For example, when brittle bonded finishes
are used, the relationship between the joints in the
concrete and the joints in the finishes shall be
considered at the outset, to reduce the risk of cracking
in undesirable locations.
Where possible, the construction joints shall be located
close to butt joints in the decking. Where shear
connectors are used, it is preferable to create the joint
to one side of the line of the shear connectors, to ensure
sound concrete around the studs. If the construction
joint cannot be made near a butt joint, it is suggested
that no more than one-third of the decking span from
a butt joint shall be left unpoured. Concreting shall
not be stopped within a sheet length, because excessive
deflections may occur when the loads on a continuous
decking sheet are not balanced either side of the
intermediate support beam.
Stop ends, usually in the form of timber or plastic
inserts, are used to create the construction joints. As
with all the joints and ends of the decking, they shall
be checked for potential grout loss.
B-1.4 Reinforcement
All reinforcement shall be properly supported so that
it does not get displaced during concreting. Plastic
stools, loops or preformed mesh may be used as
'chairs', but not plastic channels, which can induce
cracking. Chairs shall be robust. In particular, the
handling and movement of concrete carrying pipes
during pumping can cause significant local impacts
on the reinforcement.
The reinforcement that has been fixed shall be checked.
Particular attention shall be given to checking any
additional bar reinforcement, such as may be needed
around openings.
B-1.5 Grout Loss
The decking joints shall be closely butted and exposed
ends shall be "stopped* wi};h proprietary filler pieces
to avoid grout loss. Gaps greater than 5 mm shall be
sealed.
B-2 PLACEMENT
B-2.1 Concrete shall be placed in a way that minimizes
the permanent deformation of the decking. This is
particularly important for spans greater than 3 m. When
concreting is progressed in the same direction as the
span of the decking (that is, parallel to the decking
ribs), it shall be placed first over supports where the
decking is continuous, followed by the mid-span region
and finally the areas above the end supports. When
concreting is progressed in a direction perpendicular
to the decking span (that is, transverse to the decking
10
NATIONAL BUILDING CODE OF INDIA
ribs), it shall be placed first at the edge where a decking
sheet is supported by the underlap of an adjacent sheet.
This helps to ensure that longitudinal seams between
panels remain closed.
The concrete shall be well compacted, particularly near
and around any shear connectors. This may be done
using a vibrating beam, which may require adequate
supports at either ends, or an immersion poker vibrator.
Hand tamping is not recommended as a way of
compacting the concrete. For slim floors with deep
decking, or for other partially encased beams, a poker
is needed to ensure proper concrete flow around the
beams, beyond the ends of the decking.
B-2.2 Concrete Pumping
Pumping may be adopted for both normal and
lightweight concrete mixes. Flow rates in the order of
0.5 m 3 to 1 m 3 of concrete per minute may be achieved,
although, clearly, the longer the pump lines and the
higher the concrete is to be pumped, the slower the
operation. A pump may normally lift the concrete up
to 30 m. Secondary pumps, placed at intermediate
levels, may be necessary for higher lifts.
Pumplines are normally 150 mm in diameter and are
assembled in segments. As the force exerted at bends
may be significant, straight line pumping is preferred.
The lines shall be supported on timber blocks at
intervals of 2 m to 3 m. Re-setting of pumplines is
required at frequent intervals as the pour progresses.
This means that the outlet pipe shall be moved
frequently and carefully so that concrete heaping is
minimized. A minimum of two operatives are
necessary for this operation, one to hold and
manoeuvre the outlet pipe, the other to shovel away
excess concrete. No more than 4 workmen shall be
present around the pipe outlet during pumping,
because of the potential for overloading the decking.
The concrete shall not be dropped from the outlet
pipe onto the decking from a height of more than
about 1 m.
B-2.3 Skip and Barrow
Placing concrete from a skip hung from a crane may
be difficult because of obstructions from beams and
decking at higher floor levels. However, despite being
time consuming, it is sometimes efficient to use the
skip and barrow technique for small infill bays.
Skips shall have a means of controlling the rate of
discharge, and shall not be discharged from more than
0.5 m above the decking or barrow. When discharging
into a barrow, the barrow shall be supported by
thick (about 30 mm) boards covering a 2 m x 2 m area,
or by a finished part of the slab. Either provision
limits impact loads. Barrows shall be run over thick
boards placed on the mesh, which shall be supported
locally.
B-3 FINISHING, CURING AND DRYING
If power floating is to be carried out, this shall be done
within 2 h to 3 h of casting. This allows time for the
concrete to harden sufficiently.
As the concrete is only exposed on one surface of a
composite floor, it can take longer than a traditional
reinforced concrete slab to dry out.
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and 'accepted standards'
in the fulfilment of the requirements of the Code. The
latest version of a standard shall be adopted at the time
of enforcement of the Code. The standards listed may
be used by the Authority as a guide in conformance
with the requirements of the referred clauses in the
Code.
IS No.
(1) 3935: 1966
(2) 3201 : 1988
(3) 6332 : 1984
Title
Code of practice for composite
construction
Criteria for the design and
construction of precast — trusses
and purlins {first revision)
Code of practice for construction
of floor and roofs using precast
IS No. Title
doubly-curved shell units (first
revision)
10297 : 1982 Code of practice for design
and construction of floors and
roofs using precast reinforced/
prestressed concrete ribbed or
cored units
10505 : 1983 Code of practice for construction
of floors and roofs using
precast reinforced concrete
waffle units
13994 : 1994 Code of practice for design and
construction of floor and roof
with precast reinforced concrete
planks and RC joists
PART 6 STRUCTURAL DESIGN — SECTION 7B SYSTEMS BUILDING AND MIXED/COMPOSITE CONSTRUCTION
11
IS No. Title
14142 : 1994 Code of practice for design and
construction of floors and roofs
with prefabricated brick panel
14215 : 1994 Code of practice for construction
of floor and roof with RC channel
units
14242 : 1994 Code of practice for design and
construction of roof with L-Panel
units
IS No.
Title
(4)
11447:1985
Code of practice for construction
with large panel prefabricates
(5)
6061
Code of practice for construction
of floor and roof with joists and
filler blocks:
(Part 1) : 1971
With hollow concrete filler
blocks
(Part 2): 1981
With hollow clay filler blocks
{first revision)
12
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
SECTION 1 CONSTRUCTIONAL PRACTICES
2 PLANNING, MANAGEMENT AND PRACTICES
SECTION 2 STORAGE, STACKING AND HANDLING
PRACTICES
3 GENERAL
4 STORAGE, STACKING AND HANDLING OF MATERIALS
5 UNLOADING RAIL/ROAD WAGONS AND MOTOR VEHICLES
SECTION 3 SAFETY IN CONSTRUCTION OF
ELEMENTS OF A BUILDING
6 GENERAL
7 TERMINOLOGY
8 TEMPORARY CONSTRUCTION, USE OF SIDE WALLS AND
TEMPORARY ENCROACHMENTS
9 TESTING
10 INSPECTION AND RECTIFICATION OF HAZARDOUS DEFECTS
11 FOUNDATIONS
12 GENERAL REQUIREMENTS AND COMMON HAZARDS DURING
EXCAVATION
1 3 PILING AND OTHER DEEP FOUNDATIONS
14 WALLS
1 5 COMMON HAZARDS DURING WALLING
16 ROOFING
1 7 ADDITIONAL SAFETY REQUIREMENTS FOR ERECTION OF
CONCRETE FRAMED STRUCTURES (HIGH-RISE BUILDINGS)
1 8 ADDITIONAL SAFETY REQUIREMENTS FOR ERECTION OF
STRUCTURAL STEEL WORK
19 MISCELLANEOUS ITEMS
20 FINISHES
21 FRAGILE FIXTURES
22 SAFETY IN SPECIAL OPERATIONS
23 ELECTRICAL INSTALLATIONS AND LIFTS
24 GENERAL REQUIREMENTS
25 CONSTRUCTION MACHINERY
11
12
21
22
22
23
23
23
24
24
25
27
28
29
30
33
36
38
38
38
38
38
40
SECTION 4 MAINTENANCE MANAGEMENT, REPAIRS, RETROFITTING
AND STRENGTHENING OF BUILDINGS
26 MAINTENANCE MANAGEMENT
40
NATIONAL BUILDING CODE OF INDIA
27 PREVENTION OF CRACKS
28 REPAIRS AND SEISMIC STRENGTHENING OF BUILDINGS
SECTION 5 SAFETY IN DEMOLITION OF BUILDINGS
29 GENERAL
30 PRECAUTIONS PRIOR TO DEMOLITION
3 1 PRECAUTIONS DURING DEMOLITION
32 SEQUENCE OF DEMOLITION OPERATIONS
33 WALLS
34 FLOORING
35 DEMOLITION OF STEEL STRUCTURES
36 CATCH PLATFORM
37 STAIRS, PASSAGEWAYS AND LADDERS
38 MECHANICAL DEMOLITION
39 DEMOLITION OF CERTAIN SPECIAL TYPES AND ELEMENTS OF
STRUCTURES
40 LOWERING, REMOVAL AND DISPOSAL OF MATERIALS
41 MISCELLANEOUS
42 FIRST-AID
ANNEX A PROGRAMME EVALUATION AND REVIEW TECHNIQUE,
AND CRITICAL PATH METHOD
ANNEX B CHECK LIST FOR STACKING AND STORAGE OF MATERIALS
ANNEX C COMMON CAUSES FOR MAINTENANCE PROBLEMS
ANNEX D FORMAT FOR INSPECTION REPORT
ANNEX E GUIDELINES FOR MAINTENANCE OF ELECTRICAL
EQUIPMENTS
LIST OF STANDARDS
46
47
48
49
50
50
50
50
50
51
51
51
51
52
53
53
54
55
56
57
58
60
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
National Building Code Sectional Committee, CED 46
FOREWORD
This Part of the Code emphasizes the importance of carrying out all constructional operations in a safe and
efficient manner. Workers in large number, both skilled and unskilled, are engaged in the innumerable construction
works. Due to increased tempo of such a building activity and large scale mechanization, hazards of accidents
could increase considerably. It is, therefore, imperative that adequate safety rules are laid down for every phase
of construction work.
Planning the various constructional operations before hand and making adequate arrangements for procurement
and storage of materials, and the machinery to get work done is as important as carrying out these constructional
operations in accordance with good practice. Lack of planning or defective planning may result in avoidable
delay in the completion of work and consequently increased hazards from the point of view of fire, health and
structural soundness.
The first version of this Part was prepared in 1970, which was subsequently revised in 1983. In the first revision,
information regarding handling operations, that is unloading, stacking, lifting, loading and conveying of building
materials, was also given along with the storage practices. Additional information regarding the use of ladders;
safety requirements for floor and wall openings, railings and toe boards; piling and other deep foundations;
constructions involving use of hot bituminous materials; and erection of structural steel work and concrete framed
structures, etc, were included.
As a result of experience gained in implementation of 1 983 version of this part and feedback received as well as
in view of formulation of new standards in the field of constructional practices and safety and revision of some
existing standards, a need to revise this Part was felt. This revision has, therefore, been prepared to take care of
these aspects. The significant changes incorporated in this revision include:
a) The Section 1 Constructional Practices have been revamped and now includes the Planning and
Management aspects.
b) The provisions with regard to stacking and storage of building materials and components have been
updated and comprehensively covered in line with IS 4082 : 1996. This revision now also covers
provisions for materials like stones, blocks, roof tiles, partially prefabricated wall and roof components,
cinder, aluminium section, cast iron and aluminium sheets, plastic sheets, doors and windows, etc.
c) Provisions on constructional practices using bamboo have been included.
d) Provisions of safety requirements of hoists/lifts for worker during construction have been added.
e) Provisions with regard to safety at work site have been detailed incorporating aspects like preventive
measures, such as, falling material hazards prevention, fall prevention, disposal of debris, fire protection,
etc.
f) Provisions regarding safety management at work sites have been added.
g) A new section on 'Maintenance management, repairs, retrofitting and strengthening of buildings' has
been added, covering aspects like maintenance management, prevention of cracks, and repairs and
seismic strengthening of buildings.
h) Safety provisions with respect to demolition of buildings have been updated.
j) Reference to all the concerned Indian Standards have been updated.
Bamboo is a versatile renewable resource having low gestation period, characterized by high strength, low mass
and ease of working with simple tools. Resilience coupled with lightness makes it suitable for housing in
earthquake-prone and disaster-prone areas. It has the capacity to absorb more energy and shows larger deflections
before collapse and as such is safer under earth tremors. In this revision of this Part, therefore, provisions on
construction using bamboo have been incorporated. The structural design aspects are covered in Part 6 'Structural
Design, Section 3 Timber and Bamboo, 3B Bamboo'.
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
The information contained in this Part is largely based on the following Indian Standards and Special Publications:
IS No.
3696
(Part 1) : 1987
(Part 2): 1991
3764 : 1992
4082 : 1996
Title
Safety code for scaffolds and ladders:
Scaffolds
Ladders
Code of practice for excavation work {first revision)
Recommendations on stacking and storage of construction materials and components
at site (second revision)
4130 : 1991 Safety code for demolition of buildings (second revision)
4912 : 1978 Safety requirements for floor and wall openings, railing and toe boards (first revision)
5121 : 1969 Safety code for piling and other deep foundations
5916 : 1970 Safety code for construction involving use of hot bituminous materials
7205 : 1974 Safety code for erection of structural steel work
7969 : 1975 Safety code for handling and storage of building materials
8989 : 1978 Safety code for erection of concrete framed structures
13415 : 1992 Safety code for protective barrier in and around buildings
13416 Recommendations for preventive measures against hazards at work places:
(Part 1) : 1992 Falling material hazards prevention
(Part 2) : 1992 Fall prevention
(Part 3) : 1994 Disposal of debris
(Part 4) : 1994 Timber structures
(Part 5) : 1994 Fire protection
13430 : 1992 Code of practice for safety during additional construction and alteration to existing
buildings
A reference to SP 62 : 1992 'Handbook on building construction practices (excluding electrical works)' and
SP 70 : 2001 'Handbook on construction safety practices' may also be made.
All standards, whether given herein above or cross referred to in the main text of this Part, are subject to revision.
The parties to agreement based on this Part are encouraged to investigate the possibility of applying the most
recent editions of the standards.
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
1 SCOPE
This Part of the Code covers the constructional
planning, management and practices in buildings;
storage, stacking and handling of materials and safety
of personnel during construction operations for all
elements of a building and demolition of buildings. It
also covers guidelines relating to maintenance
management, repairs, retrofitting and strengthening of
buildings.
SECTION 1 CONSTRUCTIONAL
PRACTICES
2 PLANNING, MANAGEMENT AND PRACTICES
2.1 Planning Aspects
Construction planning aspects aim to identify and
develop various stages of project execution on site
which should be consistent with the management
considerations. Planning aspects evolve out of the
objectives of project and requirements of the final
completed constructed facility. These objectives could
relate to the final constraints, cost considerations,
quality standards, safety standards, environmental
considerations and health considerations. Construction
practices would, then have to satisfy these objectives
during construction phase of the project.
Having established objectives of the construction
phase, planning determines processes, resources
(including materials, equipments, human and
environmental) and monitoring system to ensure that
the practices are appropriately aligned. Adequate
knowledge about pre-construction phase evolution of
project, especially related to customer's requirements,
is an essential prerequisite for construction planning.
2.1.1 Preconstruction Phase
2.1.1.1 Besides the design aspects, preconstruction
phase should also address all the issues related to the
implementation of the design at the site through suitable
construction strategy. During the design stage, the site
conditions should be fully understood with anticipated
difficulties and avoid the risk of subsequent delays and
changes after the construction has started.
2.1.1.2 The selection of construction methods,
building systems and materials, components,
manpower and equipments and techniques are best
done in the preconstruction phase. Such selection is
influenced by the local conditions like terrain, climate,
vulnerability for disasters, etc.
2.1.1.3 Construction in busy localities of cities needs
special considerations and meticulous planning due to
restricted space, adjoining structures, underground
utilities, traffic restrictions, noise and other
environmental pollution and other specific site
constraints.
2.1.1.4 The constructability aspects of the proposed
construction methods needs to be carefully evaluated
at the planning stage to ensure ease of construction
besides optimizing the construction schedule and
achieving quality, reliability and maintainability of the
constructed facilities.
2.1.1.5 Constructional practices in hilly regions needs
to take into considerations the problem of landslides,
slope stability, drainage, etc, besides ensuring no
adverse impact on the fragile environmental conditions.
2.1.1.6 Durability of constructions in corrosive
atmospheric conditions like coastal regions and
aggressive ground situations with high chlorides and
sulphates should also be taken care of with appropriate
constructional practices.
2.1.1.7 Constructional practices in disaster prone areas
need specific planning. The type of construction, use
of materials, construction techniques require special
considerations in such areas.
2.1.1.8 Adverse weather conditions have strong
bearing on construction phase. Situations wherein
constructions are to be carried out in adverse weather
conditions, such as heavy and continuous rain fall,
extreme hot or cold weather, dust storms, etc, the
practices have to address the relevant aspects.
Accordingly, suitable design and field operations
should be adapted or redefined in anticipation of these
aspects. Some of these aspects are:
a) Site layout which enables accessibility in
adverse weather.
b) Adequate protected storage for weather
sensitive materials/equipments.
c) Protections to personnel from extreme hot/
control conditions.
d) Scheduling to allow maximization of outdoor
activities during fair weather conditions.
e) Special design and construction provisions for
activities in extreme temperature conditions
like hot or cold weather concreting, staple of
false work in extreme wind conditions (gusts).
f) Adequate lighting for shorter days in winter/
night work.
g) Design for early enclosure.
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
2.1.2 Resource Planning
Resource planning aims to identify requirement,
availability and regulatory/control processes related to
resources. Resource planning is a generic expression
but the actual process of planning is specific to the
resources considered.
In construction phases, the resources could be
categorized as materials, manufactured products,
equipments for construction, installation and
fabrication, human resources as a part of overall
organization, information resources, such as, reference
standards and other practice documents, environmental
conditions for work on site and infrastructure facilities.
Therefore, the resource planning encompasses
identification, estimation, scheduling and allocation of
resources. Resource planning needs to establish
a control system for controlling consumption
monitoring, corrective action and resource reappropriation
in the event of favourable deviation. Organizational
capability, commitment to the project requirements and
other constraints such as time and cost, need to be
considered as inputs while planning resources.
Techniques of management and planning, such as,
Programme Evaluation and Review Technique (PERT)
and Critical Path Method (CPM) {see Annex A) may
be used.
Non-availability of basic building materials (brick,
stone aggregate, etc) within reasonable lead would
influence the constructional practice by alternative
materials. The constructional practices also get
decided by the local skills of the manpower for
constructional activities. The equipment selection
would also be governed by the site constraints.
Therefore, as, the resource planning is critical to the
project viability itself, the inputs to the resource
planning need to be validated appropriately and
established for such management. Resource planning
should establish a proper system of data collection
so as to facilitate effective resources control
mechanism. Resource planning responsibility has to
be specifically defined in the overall organizational
setup.
2.1.3 Construction Phase
2.1.3.1 Organizational structure
The site management should be carried out through
suitable site organization structure with roles and
responsibilities assigned to the construction personnel
for various construction related functions. Safety
management is one of the important components of
site management.
2.1.3.2 Site layout
The layout of the construction site should be carefully
planned keeping in view the various requirements to
construction activities and the specific constraints in
terms of its size, shape, topography, traffic and other
restrictions, in public interest. A well planned site
layout would enable safe smooth and efficient
construction operations. The site layout should take
into considerations the following factors:
a) Easy access and exit, with proper parking of
vehicle and equipments during construction.
b) Properly located material stores for easy
handling and storage.
c) Adequate stack areas for bulk construction
materials.
d) Optimum location of plants and equipments
(batching plants, etc).
e) Layout of temporary services (water, power,
power suppression unit, hoists, cranes,
elevators, etc).
f) Adequate yard lighting and lighting for night
shifts.
g) Temporary buildings; site office and shelter
for workforce with use of non-combustible
materials as far as possible including
emergency medical aids.
h) Roads for vehicular movement with effective
drainage plan.
j) Construction safety with emergency access
and evacuations and security measures,
k) Fabrication yards for reinforcement
assembly, concrete precasting and shuttering
materials,
m) Fencing, barricades and signages.
2.1.3.3 Access for fire fighting equipment vehicles
Access for fire fighting equipment shall be provided
to the construction site at the start of construction and
maintained until all construction work is completed.
2.1.3.3.1 Free access from the street to fire hydrants/
static water tanks, where available, shall be provided
and maintained at all times.
2.1.3.3.2 No materials for construction shall be placed
within 3 m of hydrants/static water tanks.
2.1.3.3.3 During building operations, free access to
permanent, temporary or portable first-aid fire fighting
equipment shall be maintained at all times.
2.1.3.4 Access to the upper floors during construction
In all buildings over two storeys high, at least one
stairway shall be provided in usable condition at all
times. This stairway shall be extended upward as each
floor is completed. There shall be a handrail on the
staircase.
8
NATIONAL BUILDING CODE OF INDIA
2.1.3.5 Construction strategy and construction
sequence
Construction strategy and construction methods are to
be evolved at the planning and design stage specific to
the conditions and constraints of the project site and
implemented by the site management personnel to
ensure ease of construction and smooth flow of
construction activities. Sites of high water table
conditions with aggressive chemical contents of subsoil
needs special design considerations. Buildings with
basement in sites of high water table should be planned
with dewatering scheme with appropriate construction
sequence. Duration of dewatering should continue till
sufficient dead loads are achieved to stabilize the
buoyancy loads with adequate factor of safety. The
construction sequence should be planned taking into
consideration the following aspects:
a) Availability of resources (men, material and
equipment);
b) Construction methods employed including
prefabrication;
c) Planned construction time;
d) Design requirements and load transfer
mechanism;
e) Stability of ground like in hilly terrain;
f) Ensuring slope stability with retaining
structure before the main construction;
g) Installation and movement of heavy
equipments like cranes and piling equipments;
h) Effect of weather; and
j ) Minimum time to be spent below ground level
working.
2.1.4 Scope Management
Construction management efforts should ensure that
the project features and functions that characterise the
project scope remain as established during the design
finalization stage. Accordingly, construction phase
practices need to be oriented to manage the project
scope. As a part of overall project scope management
functions, the processes of scope planning, scope
definition and scope verification are associated with
the preconstruction phase of the project. The scope
monitoring and the change control are critical to the
construction phase leading to serious implications on
the time and cost aspects. In this respect, consolidated
brief of the project established at the end of the design
completion is an essential reference for scope baseline.
2.2 Construction Management
Construction phase of the project transfers the project
conceived on paper in the form of plans and designs,
into reality by use of resources like materials, machines
and men through one or more construction agencies.
To fulfil the construction scope with quality, in time
and under safe conditions within a reasonable cost, it
is desired that the project is planned for managing
construction for amalgamation of above resources for
their optimum use and its continuous monitoring.
Agencies managing the supervision and/or construction
are desired to plan and document a management system
with clear cut responsibilities and for managing various
parameters like scope, time, quality, health, safety and
environment and cost for implementation, monitoring
and control for their effectiveness. This may be
preferably inline with proven National/International
documentation system covering all aspects of
monitoring and controls. Various parameters to be
managed during construction are as below.
2.2.1 Time Management
Considering the importance of time in a project, it is
desirable that project is completed in the defined time
schedule to get its fruitful benefits. The system planned
should cover total schedule of completion with one or
more construction agencies, number of vendors,
identification of total resources, timely availability of
all inputs, including critical ones, its processing during
construction of a project. The system should include a
periodic review of a project with all parameters as well
as catch up plans in case of delay identified for controls
and reporting from time to time. The system planned
should preferably be computer friendly and simple to
follow for implementation, monitoring and controls
and for reporting from time-to-time.
2.2.2 Quality Management
Quality of a project should be planned for all activities
from inception to completion. It is desirable that the
system planned gives adequate assurance and controls
that it shall meet project quality objectives. The system
shall cover review of existing requirements, sub-
contracting, materials, processes and controls during
process, auditing, training of personnel, final inspection
and acceptance. All activities shall be planned and
controlled. Quality systems approach may be referred
for planning, suitable to a particular project for
implementation.
2.2.3 Health, Safety and Environement
Each project affects the safety and health of the
workmen and surroundings during construction.
Various activities having impact on health, safety and
environment need to be identified with their likely
effect and proposed preventive corrective actions,
together with the concerned statutory obligations. The
system planned for health, safety and environment shall
address and cover the above including use of personnel
protective equipments by all concerned, and reporting
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
on their monitoring and controls during project
implementation.
2.2.4 Cost Management
To keep the project under viable proposition, it is
desired that cost of the project during construction are
monitored and controlled through a documentation
system. The various parameters which may affect the
basic cost, escalations, cost due to variation in scope
and quantities, etc need to be monitored at a defined
frequency. The system planned may be in line with a
proven cost control method or similar in nature and
cost incurred vis-a-vis cost sanctioned and cost
anticipated to be reported and controlled from time to
time.
2.3 Construction Control and Practices
2.3.1 Professional Services and Responsibilities
The responsibility of professionals with regard to
planning designing and supervision of building
construction work, etc and that of the owner shall be
in accordance with Part 2 'Administration'. All
applications for permits and issuance of certificates,
etc shall be as given in Part 2 'Administration'.
Employment of trained workers shall be encouraged
for building construction activity.
2.3.2 Construction of all Elements
Construction of all elements of a building shall be in
accordance with good practice [7(1)]. Constructional
aspects using bamboo shall be as given in 2.3.3. It shall
also be ensured that the elements of structure satisfy
the appropriate fire resistance requirements as specified
in Part 4 'Fire and Life Safety' , and quality of building
materials/components used shall be in accordance with
Part 5 'Building Materials'.
2.3.3 Construction Using Bamboo
2.3.3.1 Bamboo being a versatile resource characterized
by high strength, low mass and ease of working with
simple tools, it is desirable to increasingly make
appropriate use of this material. Design of structures
using bamboo shall be done in accordance with
Part 6 'Structural Design, Section 3 Timber and
Bamboo, 3B Bamboo' . For construction using bamboo,
some of the important constructional provisions given
in 2.3.3.2 to 2.3.3.6 shall be followed.
2.3.3.2 Working finishing
2.3.3.2.1 Bamboo can be cut and split easily with very
simple hand tools. Immature bamboos are soft, pliable
and can be moulded to desired shape. It takes polish
and paint well.
2.3.3.2.2 While it is possible to walk with bamboo
simply using a machete, a few basic tools, such as,
machete, hack saw, axe, hatchet, sharpening tools,
adze, chisel (20 mm), drill, wood rasps, steel rod, and
pliers, will greatly increase the effectiveness of the
construction process.
2.3.3.2.3 For providing safety to the structure against
fire, bamboo may be given fire retardant treatment
using following chemicals; a few drops of concentrated
HC1 shall be added to the solution to dissolve the
precipitated salts:
Ammonium phosphate 3 parts
Boric acid 3 parts
Copper sulphate 1 part
Zinc chloride 5 parts
Sodium dichromate 3 parts
Water 100 parts
2.3.3.2.4 Foundations
Bamboo in direct contact with ground, bamboo on rock
or preformed concrete footing, bamboo incorporated
into concrete or bamboo piles may form the foundation
structure (see Fig. 1).
2.3.3.2.5 Floors
The floor of bamboo may be at ground level with
covering of bamboo matting, etc. In elevated floors,
bamboo members become an integral part of structural
framework of building. The floor will comprise
structural bamboo elements and bamboo decking.
2.3.3.2.6 Jointing Techniques
The jointing techniques in construction using bamboo
shall be in accordance with Part 6 'Structural Design,
Section 3 Timber and Bamboo, 3B Bamboo'.
2.3.4 Low Income Housing
For low income housing, appropriate planning and
selection of building materials and techniques of
construction have to be judiciously done and applied
in practice. Requirements of low income housing
specified in Part 3 'Development Control Rules and
General Building Requirements', shall be followed.
However, all requirements regarding structural safety,
health safety and fire safety shall be in accordance with
this Code.
2.3.5 Site Preparation
While preparing the site for construction, bush and
other wood, debris, etc, shall be removed and promptly
disposed of so as to minimize the attendant hazards.
Temporary buildings for construction offices and
storage shall be so located as to cause the minimum
fire hazards and shall be constructed from non-
combustible materials as far as possible.
10
NATIONAL BUILDING CODE OF INDIA
1A BAMBOO ON PREFORMED
CONCRETE FOOTINGS
1B BAMBOO INCORPORATED INTO CONCRETE
FOOTINGS (SINGLE POST FOOTING)
1C BAMBOO OUT OF GROUND CONTACT ON STRIP FOOTINGS OF CONCRETE (LARGE
DIAMETER THICK WALLED BAMBOO WITH CLOSELY SPACED NODES TO BE USED)
Fig. 1 Bamboo Foundations
2.3.6 Use of New/Alternative Construction Techniques
The provisions of this part are not intended to prevent
use of any construction techniques including any
alternative materials, not specifically prescribed by the
Code, provided any such alternative has been approved.
The Authority may approve any such alternative such
as ferrocement construction, row-lock (rat trap) bond
in masonry, stretcher bond in filler slab and filler slab
provided it is found that the proposed alternative is
satisfactory and conforms to the provisions of relevant
parts regarding material, design and construction and
that material, method, or work offered is, for the
purpose intended, at least equivalent to that prescribed
in the Code in quality, strength, compatibility,
effectiveness, fire and water resistance, durability and
safety.
SECTION 2 STORAGE, STACKING AND
HANDLING PRACTICES
3 GENERAL
3.1 Planning and Storage Layout
3.1.1 For any site, there should be proper planning of
the layout for stacking and storage of different
materials, components and equipments with proper
access and proper manoeuvrability of the vehicles
carrying the material. While planning the layout, the
requirements of various materials, components and
equipments at different stages of construction shall be
considered.
3.1.2 Materials shall be segregated as to kind, size and
length and placed in neat, orderly piles that are safe
against falling. If piles are high they shall be stepped
back at suitable intervals in height. Piles of materials
shall be arranged so as to allow a passageway of not
less than 1 m width in between the piles or stacks for
inspection or removal. All passageways shall be kept
clear of dry vegetation.
3.1.3 Materials shall be stored, stacked and handled
in such a manner as to prevent deterioration or intrusion
of foreign matter and to ensure the preservation of their
quality and fitness for the work.
3.1.4 Materials shall be stacked on well drained, firm
and unyielding surface. Materials shall not be stacked
so as to impose any undue stresses on walls or other
structures.
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
11
3.1.5 Materials shall be stacked in such a manner as
not to constitute a hazard to passerby. At such places
the stacks shall have suitable warning signs in day time
and red lights on and around them at night.
3.1.6 Stairways, passageways and gangways shall not
become obstructed by storage of building materials,
tools or accumulated rubbish.
3.2 Protection Against Atmospheric Agencies
Materials stored at site, depending upon the individual
characteristics, shall be protected from atmospheric
actions, such as rain, sun, winds and moisture, to avoid
deterioration,
3.3 Manual Handling
When heavy materials have to be handled manually
each workman shall be instructed by his foreman or
supervisor for the proper method of handling such
materials. Each workman shall be provided with
suitable equipment for his personal safety as necessary.
Supervisors shall also take care to assign enough men
to each such job depending on the weight and the
distance involved.
3.4 Protection Against Fire and Other Hazards
3.4.1 Materials, like timber, bamboo, coal, paints, etc,
shall be stored in such a way that there may not be any
possibility of fire hazards. Inflammable materials like
kerosene and petrol, shall be stored in accordance with
the relevant rules and regulations so as to ensure the
desired safety during storage. Stacks shall not be piled
so high as to make them unstable under fire fighting
conditions and in general they shall not be more than
4.5 m in height. The provisions given in good practice
[7(2)] shall be followed. Explosives like detonators
shall be stored in accordance with the existing
regulations pf Indian Explosives Act,
3.4.2 Materials which are likely to be affected by
subsidence of soil like precast beams, slabs and timber
of sizes shall be stored by adopting suitable measures
to ensure unyielding supports.
3.4.3 Materials liable to be affected by floods, tides,
etc shall be suitably stored to prevent their being
washed away or damaged due to floods, tides, etc.
4 STORAGE, STACKING AND HANDLING OF
MATERIALS
4.1 The storage stacking and handling of materials
generally used in construction shall be as given in 4.2
to 4.31, which have been summarized in the form of a
check list in Annex B. Exposure to asbestos fibres/
dust is known to be harmful to health of human beings.
Prescribed guidelines in accordance with good practice
[7(3)] shall be followed for handling and usage asbestos
cement products.
4.2 Cement
a) Storage and Stacking — Cement shall be
stored at the work site in a building or a shed
which is dry, leakproof and as moisture-proof
as possible. The building or shed for storage
should have minimum number of windows
and close fitting doors and these should be
kept closed as far as possible.
Cement received in bags shall be kept in such
a way that the bags are kept free from the
possibility of any dampness or moisture
coming in contact with them. Cement bags
shall be stacked off the floor on wooden
planks in such a way as to keep them about
150 mm to 200 mm clear above the floor. The
floor may comprise lean cement concrete or
two layers of dry bricks laid on a well
consolidated earth. A space of 600 mm
minimum shall be left alround between the
exterior walls and the stacks (see Fig. 2). In
the stacks the cement bags shall be kept close
together to reduce circulation of air as such
as possible. Owing to pressure on bottom
layer of bags sometimes 'warehouse pack' is
developed in these bags. This can be removed
easily by rolling the bags when cement is
taken out for use. Lumped bags, if any should
be removed and disposed off.
The height of stack shall not be more than 10
bags to prevent the possibility of lumping up
under pressure. The width of the stack shall
be not more than four bags length or 3 metres.
In stacks more than 8 bags high, the cement
bags shall be arranged alternately length-wise
and cross-wise so as to tie the stacks together
and minimize the danger of toppling over.
Cement bags s$iall be stacked in a manner to
facilitate their removal and use in the order
in which they are received; a table showing
date of receipt of cement shall be put on each
stack to know the age of cement.
For extra safety during monsoon, or when it
is expected to store for an unusually long
period, the stack shall be completely enclosed
by a water proofing membrane such as
polyethylene, which shall close on the top of
the stack. Care shall be taken to see that the
waterproofing membrane is not damaged any
time during the use.
Cement in gunny bags, paper bags and
polyethylene bags shall be stored separately.
In case cement is received in drums, these
12
NATIONAL BUILDING CODE OF INDIA
AC. OR G.I. SHEET
OR ANY KIND OF
WEATHER PROOF
ROOF
LOAD BEARING
WALL
l— D
* 10 BAGS MAXIMUM
SECTION XX
C— '
.6m
1.40m
P
A
S
s
A
G
E
.6m
1.40m
.6m
DOOR
PLAN
A = Planks
B = Wooden Battens
C = 150 Dry Bricks in Two Layer or Lean Cement Concrete
D = 150 Consolidated Earth
Fig. 2 Typical Arrangement in Cement Godown
shall be stored on plane level ground, as far
as possible near the concrete mixing place.
After taking out the required quantity of
cement, the lid of the drum shall be securely
tied to prevent ingress of moisture.
In case cement is received in silos, the silos
shall be placed near the concrete batching
b)
plan. Proper access shall be provided for the
replacement of silos.
Different types of cements shall be stacked
and stored separately.
Handling — Hooks shall not be used for
handling cement bags unless specifically
permitted by the engineer-in-charge.
FART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
13
For information regarding bulk handling of
cement, see 4.4.
4.3 Lime
4.3.1 Quicklime Before Slaking
a) Storage and stacking — Quicklime should be
slaked as soon as possible. If unavoidable it
may be stored in compact heaps having only
the minimum of exposed area. The heaps shall
be stored on a suitable platform and covered
to avoid direct contact with rain or being
blown away by wind. In case quick lime is
stored in a covered shed, a minimum space
of 300 mm should be provided alround the
heaps to avoid bulging of walls.
Unslaked lime shall be stored in a place
inaccessible to water and because of fire
hazards, shall be segregated from the
combustible materials.
b) Handling — See 4.4.
4.3.2 Hydrated Lime
a) Storage and stacking — Hydrated lime is
generally supplied in containers, such as jute
bags lined with polyethylene or craft paper
bags. It should be stored in a building to
protect the lime from dampness and to
minimize warehouse deterioration.
The building should be with a concrete floor
and having least ventilation to eliminate
draughts through the walls and roof. In
general, the recommendations given in 4.2 for
storing of cement shall be applicable for
hydrated lime. When air movement is reduced
to a practical minimum, hydrated lime can be
stored for up to three months without
appreciable change.
b) Handling — See 4.4.
4.3.3 Dry Slaked Lime
a) Storage and stacking — The lime shall be
stored in a dry and closed godown.
b) Handling — See 4.4.
4.4 Handling of Cement and Lime
Workmen, handling bulk cement or lime shall wear
protective clothing, respirators, and goggles; shall be
instructed in the need of cleanliness to prevent
dermatitis, and shall be provided with hand cream,
petroleum jelly, or similar preparation for protection
of exposed skin.
Bulk cement stored in silos or bins may fail to feed
to the ejection system. When necessary to enter a silo
or bin for any purpose, the ejection system employed
shall be shut down and locked out electrically as well
as mechanically. When necessary for a workman to
enter such storage area, he shall wear a life-line, with
another workman outside the silo or hopper attending
the rope.
4.5 Masonry Units
a) Stones — Stones of different sizes, types and
classification shall be stored separately.
Stones shall be stacked on dry firm ground in
a regular heap not more than 1 m in height.
^^^-^WS(^pc^S«^- stones shall be stacked against
1 support on a firm dry ground in tiers,
up to a height of 1.2 m. A distance of about
0.8 m shall be kept between two adjacent
stacks.
b) Bricks— r Bricks shall be stacked in regular
tiers fas and when they are unloaded to
minimize breakage and defacement. These
shall not be dumped at site. In the case of
bricks made 1 from clays containing lime
KANKAR, the bricks in stack should be
thoroughly soaked in water (docked) to
prevent lime bursting.
Bricks shall be stacked on dry firm ground.
For proper inspection of quality and east in
counting, the stacks shall be 50 bricks long,
10 bricks high and not more than 4 bricks in
width, the bricks being placed on edge, two
at a time along the width of the stack. Clear
distance between adjacent stacks shall not be
less than 0.8 m. Bricks of each truck load shall
be put in one stack. Bricks of different types,
such as, clay bricks, clay fly ash bricks, fly
ash lime bricks, sand lime (calcium silicate)
bricks shall be stacked separately. Bricks of
different classifications from strength
consideration and size consideration (such as,
conventional and modular) shall be stacked
separately. Also bricks of different types, such
as, solid, hollow and perforated shall be
stacked separately.
c) Blocks — Blocks are available as hollow and
solid concrete blocks, hollow and solid light
weight concrete blocks, autoclaved aerated
concrete blocks, concrete stone masonry
blocks and soil based blocks. Blocks shall be
unloaded one at a time and stacked in regular
tiers to minimize breakage and defacement.
These shall not be dumped at site. The height
of the stack shall not be more than 1.2 m, the
length of the stack shall not be more than
3.0 m, as far as possible and the width shall
be of two or three blocks. Normally blocks
cured for 28 days only should be received at
14
NATIONAL BUILDING CODE OF INDIA
site. In case blocks cured for less than 28 days
are received, these shall be stacked separately.
All blocks should be water cured for 10 to 14
days and air cured for another 15 days; thus
no blocks with less than 28 days curing shall
be used in building construction. Blocks shall
be placed close to the site of work so that least
effort is required for their transportation. The
date of manufacture of the blocks shall be
suitably marked on the stacks of blocks
manufactured at factory or site,
d) Handling — Brick stacks shall be placed close
to the site of work so that least effort is
required to unload and transport the bricks
again by loading on pallets or in barrows.
Unloading of building bricks or handling in
any other way likely to damage the corners
or edges or other parts of bricks shall not be
permitted.
4.6 Floors, Wall and Roof Tiles
a) Storage and Stacking — Floor, wall and clay
roof tiles of different types, such as, cement
concrete tiles (plain, coloured and terrazzo) and
ceramic tiles (glazed and unglazed) shall be
stacked on regular platform as far as possible
under cover in proper layers and in tiers and
they shall not be dumped in heaps. In the stack,
the tiles shall be so placed that the mould
surface of one faces that of another. Height of
the stack shall not more than 1 m.
Tiles of different quality, size and thickness
shall be stacked separately to facilitate easy
removal for use in work. Tiles when supplied
by manufacturers packed in wooden crates
shall be stored in crates. The crates shall be
opened one at a time as and when required
for use.
b) Handling — Ceramic tiles and roof tiles are
generally supplied in cartons which shall be
handled with care to avoid breakage. It is
preferable to transport these at the site on
platform trolleys.
4.7 Aggregate
a) Storage and Stacking — Aggregates shall be
stored at site on a hard dry and level patch of
ground. If such a surface is not available, a
platform of planks or old corrugated iron
sheets, or a floor of bricks, or a thin layer of
lean concrete shall be made so as to prevent
the mixing with clay, dust, vegetable and other
foreign matter.
Stacks of fine and coarse aggregate shall be
kept in separate stock piles sufficiently
removed from each other to prevent the
material at the edges of the piles from getting
intermixed. On a large job it is desirable to
construct dividing walls to give each type of
aggregates its own compartment. Fine
aggregates shall be stacked in a place where
loss due to the effect of wind is minimum,
b) Handling — When withdrawals are made
from stock piles, no over hang shall be
permitted.
Employees required to enter hoppers shall be
equipped with safety belts and life-lines,
attended by another person. Machine driven
hoppers, feeders, and loaders shall be locked
in the off position prior to entry electrically
as well as mechanically.
4.8 Pulverized Fuel Ash/Fly Ash
a) Storage and Stacking — Fly ash shall be
stored in such a manner as to permit easy
access for proper inspection and identification
of each consignment. Fly ash in bulk
quantities shall be stored in stack similar to
fine aggregates, avoiding any intrusion of
foreign matter. Fly ash in bags shall be stored
in stacks not more than 10 bags high.
b) Handling — See 4.4.
4.9 Cinder
Cinder shall be stored in bulk quantities in stacks
similar to coarse aggregates avoiding any extrusion of
foreign matter.
4.10 Timber
a) Storage and Stacking — Timber shall be
stored in stacks upon well treated and even
surfaced beams, sleepers or brick pillars so
as to be above the ground level by at least
1 50 mm to ensure that the timber will not be
affected by accumulation of water under it.
Various members shall preferably be stored
separately in different lengths, and material
of equal lengths shall be piles together in
layers with woodeti battens, called crossers,
separating one layer from another. The
crossers shall be of sound wood, straight and
uniform in thickness. In case, where separate
crossers are not available smaller sections of
the available structural timber may be
employed in their place. In any layer an air
space of about 25 mm shall be provided
between adjacent members. The longer pieces
shall be placed in the bottom layers and
shorter pieces in the top layers but one end of
the stack shall be in true vertical alignment.
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
15
The crossers in different layers shall be in
vertical alignment. The most suitable width
and height of a stack are recommended to be
about 1.5 m and 2.0 m. Distance between
adjacent stacks is recommended to be at least
450 mm. In case the stacking with the help of
battens is not possible, the timber may be
close piled in heaps on raised foundations with
the precautions specified above.
The stacks shall be protected from hot dry
winds or direct sun and rain. Heavy weights,
such as metal rails or large sections of wood,
are recommended to be placed on the top of
the stack to prevent distortion or warping of
the timber in the stack. In case timber is to be
stored for about a year or more, to prevent
end-cracking in the material, the ends of all
members shall be coated with coal tar,
aluminium leaf paints (hardened gloss oil),
microcrystalline wax or any other suitable
material,
b) Care must be taken that handler or workmen
are not injured by rails, straps, etc, attached
to the used timber. This applies particularly
to planks and formwork for shuttering.
4.11 Bamboo
4.11.1 The site shall be properly inspected and termite
colonies or mounds if detected shall be destroyed.
All refuse and useless cellulosic materials shall be
removed from the site. The ground may then be
disinfected by suitable insecticides. The area should
have good drainage.
4.11.2 Bamboo may preferably be stacked on high
skids or raised platform atleast 300 mm above ground.
Storage under cover reduces the liability to fungal
attack. Good ventilation and frequent inspection are
important,
4.11.3 Bamboo dries by air-seasoning under cover in
the storage yards from 6 to 12 weeks time.
4.11.4 Prophylactic treatment of bamboo during
storage prevents losses due to fungi and insects even
under open storage. Following chemicals are found
suitable at the coverage rate of 24 litres per tonne.
Sodium pentachlorophenate : 1 percent solution
Boric acid + borax (1:1) : 2 percent solution
Sodium pentachlorophenate
+ boric acid + borax (5:1:1) : 2.5 percent solution
A mixture of these compounds yields the best results.
NOTE — For better protection of structural bamboo (if stored
outside), repetition of the treatment after four to six months is
desirable.
4.12 Partially Prefabricated Wall and Roof
Components
a) Storage and Stacking — The wall components
comprise blocks, sills, lintels, etc. The blocks
shall be stacked in accordance with 4.5(c).
These shall be stacked on plane level ground
having a floor of bricks or a thin layer of lean
concrete.
The roof components such as precast RC
joists, prefabricated brick panels, RC planks,
channel units, cored units, waffle units,
L-panel, single tee and double tee sections,
ferrocement panels, etc shall be unloaded as
individual components. These shall be
stacked on plane level ground having a floor
of bricks or a thin layer of lean concrete. RC
planks, prefabricated brick panels and
ferrocement panels shall be stacked against a
brick masonry wall in slightly inclined
position on both sides of the wall. Channel
units, cored units and L-panels shall be
stacked one over the other up to five tiers.
The waffle units shall be stacked upside down
as individual units. The RC joists, single tee
and double tee sections shall be stacked as
individual units one adjacent to the other. The
distance between any two adjacent stacks
shall not be less than 450 mm.
b) Handling — The components shall be
handled by holding the individual component
by holding a specified points so that the
stresses due to handling are minimized.
4.13 Steel
a) Storage and Stacking — For each classification
of steel, separate areas shall be earmarked. It
is desirable that ends of bars and sections of
each class be painted in distinct separate
colours. Steel reinforcement shall be stored
in a way as to prevent distortion and corrosion.
It is desirable to coat reinforcement with
cement wash before stacking to prevent
scaling and rusting.
Bars of different classification, sizes and
lengths shall be stored separately to facilitate
issues in such sizes and lengths as to minimize
wastage in cut from standard lengths.
In case of long storage or in coastal areas,
reinforcement bars shall be stacked above
ground level by at least 150 mm and a coat of
cement wash shall be given to prevent scaling
and rusting.
Structural steel of different sections, sizes and
lengths shall be stored separately. It shall be
16
NATIONAL BUILDING CODE OF INDIA
stored above ground level by at least 150 mm
upon platforms, skids or any other suitable
supports to avoid distortion of sections. In
case of coastal areas or in case of long storage,
suitable protective coating of cement wash
shall be given to prevent scaling and rusting,
b) Handling — Tag lines shall be used to control
the load in handling reinforcements or
structural steel when a crane is employed.
Heavy steel sections and bundles shall be
lifted and carried with the help of slings and
tackles and shall not be carried on the
shoulders of the workmen.
4.14 Aluminium Sections
a) Storage and Stacking — Aluminium sections
of different classification, sizes and lengths
shall be stored separately, on a level platform
under cover.
b) Handling — The aluminium sections shall not
be pulled or pushed from the stack nor shall
be slided over each other, to protect the
anodizing layer.
4.15 Doors, Windows and Ventilators
a) Storage and Stacking — Metal and plastic
doors, windows and ventilators shall be
stacked upright (on their sills) on level ground
preferably on wooden battens and shall not
come in contact with dirt or ashes. If received
in crates they shall be stacked according to
manufacturer's instructions and removed
from the crates as and when required for the
work.
Metal and plastic frames of doors, windows
and ventilators shall be stacked upside down
with the kick plates at the top. These shall
not be allowed to stand for long in this manner
before being fixed so as to avoid the door
frames getting out of shape and hinges being
strained and shutters drooping.
During the period of storage of aluminium
doors, windows and ventilators, these shall
be protected form loose cement and mortar
by suitable covering, such as tarpaulin. The
tarpaulin shall be hung loosely on temporary
framing to permit circulation of air to prevent
moisture condensation.
All timber and other lignocellulosic material
based frames and shutters shall be stored in a
dry and clean covered space away from any
infestation and dampness. The storage shall
preferably be in well -ventilated dry rooms.
The frames shall be stacked one over the other
distances to keep the stack vertical and
straight. These cross battens should be of
uniform thickness and placed vertically one
above the other. The door shutters shall be
stacked in the form of clean vertical stacks
one over the other and at least 80 mm above
ground on pallets or suitable beams or rafters.
The top of the stack shall be covered by a
protecting cover and weighted down by
means of scantlings or other suitable weights.
The shutter stack shall rest on hard and level
surface.
If any timber or other lignocellulosic material
based frame or shutter becomes wet during
transit, it shall be kept separate from the
undamaged material. The wet material may
be dried by stacking in shade with battens in
between adjacent boards with free access of
dry air. Separate stacks shall be built up for
each size, each grade an each type of material.
When materials of different sizes, grades and
types are to be stacked in one stack due to
shortage of space, the bigger size shall be
stacked in the lower portion of the stacks.
Suitable pallets or separating battens shall be
kept in between the two types of material.
Precast concrete door and window frames
shall be stored in upright position adopting
suitable measures against risk of subsidence
of soil/support,
b) Handling — While unloading, shifting,
handling and stacking timber or other
lignocellulosic material based, metal and
plastic door and window frames and shutters,
care shall be taken that the pieces are not
dragged one over the other as it may cause
damage to their surface particularly in case
of the decorative shutters. The pieces should
be lifted and carried preferably flat avoiding
damage to corners or sides.
4.16 Roofing Materials
4.16.1 Roofing sheets shall be stored and stacked in
such a manner as not to damage them in any way.
Damaged sheets shall ndt be stacked with sound
materials. All damaged sheets shall be salvaged as early
as possible.
4.16.2 Asbestos Cement Sheet
a) Storage and stackings — Asbestos cement
sheets shall be stacked to a height of not more
than one metre on firm and level ground, with
timber or other packing beneath them. If
stacked in exposed position, they shall be
protected from damage by the winds.
b) Handling — Not more than two sheets shall
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
17
be first pushed forward along the valley line
say about one fourth of the sheet length and
preferably carried by two workmen. Asbestos
cement sheets shall be lowered or raised
gently and not thrown.
4.16.3 CGI Sheets
a) Storage and stacking — CGI sheets shall be
stacked in not more than 100 bundles per
stack built solidly, each bundle consisting of
10 sheets. Bundles shall be so laid that the
corrugations run in the same directions in
every course. One end of the stack shall be
raised by 100 mm to 150 mm to allow water
flowing freely. If the sheets are not to be used
immediately, these shall be stacked under roof
cover.
b) Handling — In bulk handling of CGI sheets,
workmen shall be provided with suitable hand
protection.
4.17 Boards
4.17.1 Gypsum Boards
a) Storage and stacking — Gypsum boards shall
be stored flat in a covered clean and dry place.
b) Handling — See 4.11.2(b).
4.17.2 Plywood, Fibre Board, Particle Board, Block
Board, etc
a) Storage and Stacking — Plywood, fibre board,
particle board, block board, etc, shall not be
stored in the open and exposed to direct sun
and rain. The boards shall be stacked on a flat
dunnage, on the top of which a wooden
frame shall be constructed with battens of
50 mm x 25 mm (Min) in such a way that it
supports all four edges and corners of the
boards with intermediate battens placed at
suitable intervals to avoid warping. If required,
the stack shall be adequately raised above
ground level to ensure that it will not be
affected by accumulation of water under it.
The board shall be stacked in a solid block in
a clear vertical alignment. The top sheet of
each stack shall be suitably weighed down to
prevent warping, wherever necessary.
b) Handling — The board shall be unloaded and
stacked with utmost care avoiding damage to
the corners and surface. In case of decorative
plywood and decorative boards, the surfaces
of which are likely to get damaged by
dragging one sheet over another, it is
advisable that these are lifted as far as possible
in pairs facing each other.
4.18 Plastic and Rubber Flooring Sheets and Tiles
a) Storage and Stacking — Plastic and rubber
sheets have tendency to break-down during
storage. Plastic and rubber sheets shall
be stored according to manufacturer's
instructions.
The coolest store room available shall be
utilized for the storage of the sheets. The store
rooms where the sheets are stored shall be well
ventilated and direct light should not be
allowed to fall on them.
The sheets shall be stored away from electric
generators, electric motors, switchgears and
other such electrical equipment as they
produce harmful gases as they produce
harmful order in their vicinity.
Contamination of the sheets with vegetable
and mineral oils; greases; organic solvents;
acids and their fumes; alkalies; dust and
grit shall be prevented. Where greasy
contamination occurs this shall be removed
immediately with petrol and the sheets and
tiles thoroughly wiped dry and dusted with
chalk chalk.
Undue stretch and strain, kinks, sharp bends
or folds of the sheets and tiles shall be
avoided. In case of long storage, the sheets
shall be turned over periodically and treated
with chalk powder, if necessary.
b) Handling — While handling plastic and
rubber sheets, workmen shall lift the sheets
and carry them flat to avoid sharp bends or
folds of the sheets.
4.19 Glass Sheets
a) Storage and Stacking — It is important that
all glass sheets whether stored in crates or not
shall be kept dry. Suitable covered storage
space shall be provided for the safe storage
of the glass sheets. The glass sheets shall be
lifted and stored on their long edges and shall
be put into stacks of not more than 25 panes,
supported at two points by fillets of wood at
about 300 mm from each end. The first pane
laid in each stack shall be so placed that its
bottom edge is about 25 mm from the base of
the wall or other support against which the
stack rests. The whole stack shall be as close
and as upright as possible. To prevent slipping
on smooth floor, the floor shall be covered
with gunny bags. The glass sheets of different
sizes, thickness and type shall be stacked
separately. The distance between any two
stacks shall be of the order of 400 mm.
18
NATIONAL BUILDING CODE OF INDIA
b) Handling — Workmen handling glass panes,
waste glass pieces and fibre glass shall be
provided with suitable hand protection. In
removing glass sheets from crates, due care
shall be taken to avoid damages. Glass edges
shall be covered or otherwise protected to
prevent injuries to workmen.
4.20 Cast Iron, Galvanized Iron and Asbestos
Cement Pipes and Fittings
a) Storage and Stacking — The pipes shall be
unloaded where they are required, when the
trenches are ready to receive them.
Storage shall be provided at the bottom layer
to keep the stack stable. The stack shall be in
pyramid shape or the pipes placed length- wise
and cross-wise in alternate layers. The
pyramid stack is advisable in smaller diameter
pipes for conserving space in storing them.
The height of the stack shall not exceed 1 .5 m.
Each stack shall contain only pipes of the
same class and size.
Each stack shall contain only pipes of same
class and size, with consignment or batch
number marked on it with particulars or
suppliers wherever possible.
Cast iron detachable joints and fittings shall
be stacked under cover and separated from
the asbestos cement pipes and fittings.
Rubber rings shall be kept clean, away from
grease, oil, heat and light.
b) Handling — Pipes in the top layer shall be
handled first. At a time only one pipe shall be
handled by two labourers while conveying
to the actual site and shall be carried
on shoulders. Fittings shall be handled
individually.
4.21 Polyethylene Pipes
a) Storage and Stacking — Black polyethylene
pipes may be stored either under cover or in
the open. Natural polyethylene pipes,
however, should be stored under cover and
protected from direct sunlight.
Coils may be stored either on edge or stacked
flat one on top of the other, but in either case
they should not be allowed to come into
contact with hot water or steam pipes and
should be kept away from hot surface.
Straight lengths should be stored on horizontal
racks giving continuous support to prevent the
pipe taking on a permanent set.
Storage of pipes in heated areas exceeding
27°C should be avoided.
b) Handling — Removal of pipe from a pile shall
be accomplished by working from the ends
of the pipe.
4.22 Unplasticized PVC Pipes
a) Storage and Stacking — Pipes should be
stored on a reasonably flat surface free from
stones and sharp projections so that the pipe
is supported throughout its length. The pipe
should be given adequate support at all times.
In storage, pipe racks should be avoided. Pipe
should not be stacked in large piles especially
under warm temperature conditions as the
bottom pipes may distort thus giving rise to
difficulty in jointing. Socket and spigot pipes
should be stacked in layers with sockets
placed at alternate ends or the stacks to avoid
lopsided stacks.
It is recommended not to store a pipe inside
another pipe. On no account should pipes be
stored in a stressed or bend condition or near
a source of heat. Pipes should not be stacked
more than 1.5 m high. Pipes of different sizes
and classes should be stacked separately.
In tropical conditions, pipes should be stored
in shade. In very cold weather, the impact
strength of PVC is reduced making it brittle.
The ends of pipe should be protected from
abrasion particularly those specially prepared
for jointing either spigot or socket solvent
welded joints or soldered for use with
couplings.
If due to unsatisfactory storage or handling a
pipe become brittle in very cold weather.
b) Handling — Great care shall be exercised in
handling these pipes in wintry conditions as
these come brittle in very cold weather.
4.23 Pipes of Conducting Materials
a) Storage and Stacking — Pipes shall be
stacked on solid level sills and contained in a
manner to prevent spreading or rolling of the
pipe. Where quantity storage is necessary,
suitable packings shall be placed between
succeeding layers to reduce the pressure and
resulting spreading of the pile.
In stacking and handling of pipes and other
conducting materials, the following nunimum
safety distances shall be ensured from the
overhead power lines:
11 kV and below 1.40 m
Above 1 1 and below 33 kV 3.60 m
Above 33 and below 132 kV 4.70 m
Above 132 and below 275 kV 5.70 m
Above 275 and below 400 kV 6.50 m
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
19
b) Handling — Removal of pipes from a pile
shall be accomplished by working from the
ends of the pipe. During transportation, the
pipes shall be so secured as to insure against
displacement.
4.24 Piles and Poles
a) Storage and Stacking — Piles and poles shall
be carefully stacked on solid, level sills so as
to prevent rolling or spreading of the pile.
The storage area shall be maintained free of
vegetation and flammable materials.
b) Handling — When placing piles or poles on
the stack, workmen shall work from the ends
of the piles/poles. Similar precautions shall
be observed in removal of piles/poles from
the stack. Tag lines shall be used to control
piles and poles when handling for any
purpose.
In stacking and handling of piles and poles,
precautions as laid down in 4.18(a) shall be
followed.
4.25 Paints, Varnishes and Thinners
a) Storage and Stacking — Paints, varnishes,
lacquers, thinners and other flammable
materials shall be kept in properly sealed or
closed containers. The containers shall be kept
in a well ventilated location, free from
excessive heat, smoke, sparks or flame. The
floor of the paint stores shall be made up of
100 mm thick loose sand.
Paint materials in quantities other than
required for daily use shall be kept stocked
under regular storage place.
Where the paint is likely to deteriorate with
age, the manner of storage shall facilitate
removal and use of lots in the same order in
which they are received.
Temporary electrical wirings/fittings shall not
be installed in the paint store. When electric
lights, switches or electrical equipment are
necessary, they shall be of explosion proof
design.
b) Handling — Ventilation adequate to prevent
the accumulation of flammable vapours to
hazardous levels of concentration shall be
provided in all areas where painting is done.
When painting is done is confined spaces
where flammable or explosive vapours may
develop, any necessary heat shall be provided
through duct work remote from the source of
flame.
Sources of ignition, such as open flame and
exposed heating elements, shall not be
permitted in area or rooms where spray
painting is done nor shall smoking be allowed
there.
Care should be taken not to use any naked
flame inside the paint store. Buckets
containing sand shall be kept ready for use in
case of fire. Fire extinguishers when required
shall be of foam type conforming to accepted
standards [7(4)].
Each workman handling lead based paints
shall be issued Vz litre milk per day for his
personal consumption.
4.26 Bitumen, Road Tar, Asphalt, Etc
a) Storage and Stacking — Drums or containers
containing all types of bitumen, road tar,
asphalt, etc, shall be stacked vertically on their
bottoms in up to three tiers. Leaky drums shall
be segregated. Empty drums shall be stored
in pyra midal stacks neatly in rows.
b) Handling — See 19.3.1.2 and 19.3.4.
4.27 Bituminous Roofing Felts
a) Storage and Stacking — Bituminous roofing
felts shall be stored away from other
combustible materials and shall be kept under
shade.
b) Handling — Bituminous roofing felts should
be handled in a manner to prevent cracking
and other damages.
4.28 Flammable Materials
a) Storage and Stacking — In addition to the
requirements as laid down in 3.4, the
following provisions shall also apply:
1 ) Outdoor storage of drums requires some
care to avoid contamination because
moisture and dirt in hydraulic brake and
transmission fluid, gasoline, or lubricants
may cause malfunction or failure of
equipment* with possible danger to
personnel. The storage area should be
free of accumulations of spilled products,
debris and other hazards.
2) Compressed gases and petroleum
products shall not be stored in the same
building or close to each other. Storage
of petroleum products should be as per
Petroleum Rules.
b) Handling — Petroleum products delivered to
the job site and stored there in drums shall be
protected during handling to prevent loss of
identification through damage to drum
20
NATIONAL BUILDING CODE OF INDIA
markings, tags, etc. Unidentifiable petroleum
products may result in improper use, with
possible fire hazard, damage to equipment or
operating failure.
Workmen shall be required to guard carefully
against any part of their clothing becoming
contaminated with flammable fluids. They
shall not be allowed to continue work when
their clothing becomes so contaminated.
4.29 Water
Water to be stored for construction purposes shall be
stored in proper tanks to prevent any organic impurities.
The aggregate capacity of storage tanks shall be
determined after taking into account the requirements
of fire fighting.
4.30 Sanitary Appliances
a) Storage and Stacking — All sanitary
appliances shall be carefully stored under
cover to prevent damage. When accepting and
storing appliances, consideration shall be
given to the sequence of removal from the
store to the assembly positions. Vitreous
fittings shall be stacked separately from the
metal ones.
b) Handling — Bigger sanitary appliances shall
be handled one at a time. Traps, water seals
and gullies shall be handled separately. While
handling sanitary fittings they shall be free
from any oil spillings, etc. The hands of the
workers shall also be free from any oily
substance. Before lowering the appliances in
their position the supporting brackets,
pedestals, etc, shall be checked for their
soundness and then only the fixtures be
attached.
4.31 Other Materials
Polymeric materials such as coatings, sheetings,
reflective surfacings/sheetings, etc shall be stored as
per the manufacturers' instructions. Special precautions
shall be taken in case of storage, handling and usage
of toxic materials.
Small articles like screws, bolts, nuts, door and window
fittings, polishing stones, protective clothing, spare
parts of machinery, linings, packings, water supply and
sanitary fittings, and electrical fittings, insulation
board, etc, shall be kept in suitable and properly
protected containers or store rooms. Valuable small
materials shall be kept under lock and key.
4.32 Special Considerations
4.32.1 Materials constantly in use shall be relatively
nearer the place of use.
4.32.2 Heavy units like precast concrete members shall
be stacked near the hoist or the ramp.
4.32.3 Materials which normally deteriorate during
storage shall be kept constantly moving, by replacing
old materials with fresh stocks. Freshly arrived
materials shall never be placed over materials which
had arrived earlier.
4.32.4 Appropriate types of fire extinguishers shall be
provided at open sites where combustible materials are
stored and for each storage shed/room where
flammable/combustible materials are stored. For
guidance regarding selection of the appropriate types
of fire extinguishers reference may be made to good
practice [7(4)]. It is desirable that a minimum of two
extinguishers are provided at each such location.
4.32.5 Workers handling excavated earth from
foundation, particularly if the site happens to be
reclaimed area or marshy area or any other infected
area, shall be protected against infection affecting their
exposed body portions.
4.32.6 House Keeping
Stairways, walkways, scaffolds, and accessways shall
be kept free of materials, debris and obstructions. The
engineer-in-charge/the foreman shall initiate and carry
out a programme requiring routine removal of scrap
and debris from scaffolds and walkways.
4.32.7 Where stacking of the materials is to be done
on road side berms in the street and other public place,
the owner shall seek permission from the Authority
for such stacking and also for removing the remnants
of the same after the construction is over, so as to avoid
any hazard to the public.
5 UNLOADING RAIL/ROAD WAGONS AND
MOTOR VEHICLES
5.1 Loading and Unloading Rail/Road Wagons
5.1.1 Appropriate warning signals shall be displayed
to indicate that the wagons shall not be coupled or
moved.
5.1.2 The wheels of wagons shall always be sprigged
or chained while the wagons are being unloaded. The
brakes alone shall not be depended upon.
5.1.3 Special level bars shall preferably be used for
moving rail wagons rather than ordinary crow bars.
5.1.4 Where gangplanks are used between wagons and
platforms of piles (heaps), cleats at lower end of
gangplank, or pin through end of gangplanks, shall be
used to prevent sliding. If gangplank is on a gradient,
cleats or abrasive surface shall be provided for the
entire length.
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
21
5.1.5 When rail/road wagons are being loaded or
unloaded near passageways or walkways, adequate
warning signals shall be placed on each end of the
wagon to warn pedestrians.
other hazards wherever specified by the Local/State
Authority or in the Acts of the Government take
precedence over whatever is herein specified in case
of a doubt or dispute.
5.2 Loading and Unloading from Motor Vehicles 63 Safety Management
5.2.1 The motor vehicles shall be properly blocked
while being loaded or unloaded; brakes alone shall not
be depended upon to hold them.
5.2.2 When motor vehicles are being loaded or
unloaded near passageways or walkways, adequate
warning signs shall be placed on each end of the vehicle
to warn the pedestrians.
5.3 Handling Heavy/Long Items
5.3.1 Loading and unloading of heavy items, shall, as
far as possible, be done with cranes or gantries. The
workman shall stand clear of the material being moved
by mechanical equipment. The slings and the ropes
used shall be of adequate load carrying capacity, so as
not to give way and result in accidents.
5.3.2 While heavy and long components are being
manually loaded into motor vehicle, wagons, trailer,
etc, either wooden sleepers or steel rails of sufficient
length and properly secured in position shall be put in
a gentle slope against the body of the wagon/vehicle
at 3 or 4 places for loading. These long items shall be
dragged, one by one, gently and uniformly along these
supports by means of ropes, being pulled by men with
feet properly anchored against firm surface. As soon
as the items come on the floor of the vehicle, the same
may be shifted by crowbars and other suitable leverage
mechanism, but not by hands to avoid causing accident
to the workmen.
5.3.3 Similar procedure as outlined in 5.3.2 shall
be followed for manual unloading of long or heavy
items.
SECTION 3 SAFETY IN CONSTRUCTION
OF ELEMENTS OF A BUILDING
6 GENERAL
6.1 The provisions of this Section shall apply to the
erection/alterational of the various parts of a building
or similar structure. The construction of the different
elements shall conform to 2.3.2.
6.2 Other Laws
Nothing herein stated shall be construed to nullify any
rules, regulations, safety standards or statutes of the
local state governments or those contained in the
various Acts of the Government of India. The specific
Rules, Regulations and Acts pertaining to the
protection of the public or workmen from health and
6.3.1 The safety of personnel engaged in building
construction should be ensured through a well planned
and well organized mechanism. For this, depending
on the size and complexity of building construction
project, safety committee shall be constituted to
efficiently manage all safety related affairs. The site
in-charge or his nominee of a senior rank shall head
the committee and a safety officer shall act as member-
secretary. The meetings of the safety committee shall
be organized regularly say fortnightly or monthly
depending on the nature of the project, however,
emergency meetings shall be called as and when
required. The safety committees shall deal with all the
safety related issues through well structured agenda,
in the meetings and all safety related measures installed
at the site and implementation thereof shall be
periodically reviewed.
6.3.2 Notwithstanding the guidelines given in 6.3.1,
all provisions given in relevant Act/Rules/Regulations
as amended from time to time shall be followed; in
this regard, reference shall also be made to the Building
and Other Construction Workers Act, 1996 and the
Rules/Regulations framed thereunder.
7 TERMINOLOGY
7.1 For the purpose of this Part the following
definitions shall apply.
7.2 Authority Having Jurisdiction — The Authority
which has been created by a statute and which for the
purpose of administering the Code/Part, may authorize
a committee or an official to act on its behalf;
hereinafter called the 'Authority'.
7.3 Construction Equipment — All equipment,
machinery, tools and temporary retaining structures
and working platforms, that is, tools, derricks, staging,
scaffolds, runways, ladders and all material, handling
equipment including safety devices.
7.4 Floor Hole — An opening measuring less than
300 mm but more than 25mm in its least dimension,
in any floor, platform, pavement, or yard, through
which materials but not persons may fall; such as, a
belt hole, pipe opening or slot opening.
7.5 Floor Opening — An opening measuring 300 mm
or more in its least dimension, in any floor, platform,
pavement or yard through which person may fall; such
as hatch way, stair or ladder opening, pit or large
manhole.
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NATIONAL BUILDING CODE OF INDIA
7.6 Guard Railing — A barrier erected along exposed
edges of an open side floor opening, wall opening,
ramp, platform, or catwalk or balcony, etc, to prevent
fall of persons.
7.7 Materials Handing Hoists — A platform,
bucket or similar enclosure exclusively meant for
the lifting or lowering of construction material the
hoists being operated from a point outside the
conveyance.
7.8 Pile Rig — The complete pile driving equipment
comprising piling frame, leader, hammer, extractor
winch and power unit. Complete pile driving rig may
be mounted on rafts or pontoon or rails. Pile rig may
also be a mobile unit mounted on trailers or trucks, or
a special full revolving rig for raking piles.
7.9 Platform — A working space for persons,
elevated above the surrounding floor or ground, such
as balcony or platform for the operation of machinery
and equipment.
7.10 Scaffold — A temporary erection of timber or
metal work used in the construction, alteration or
demolition of a building, to support or to allow the
hoisting and lowering of workmen, their tools and
materials.
7.11 Toe Board — A vertical barrier erected along
exposed edge of a floor opening, wall opening,
platform, catwalk or ramp to prevent fall of materials
or persons.
7.12 Wall Hole — An opening in any wall or partition
having height of less than 750 mm but more than
25 mm and width unrestricted.
7.13 Wall Opening — An opening in any wall or
partition having both height of at least 750 mm and
width of at least 450 mm.
8 TEMPORARY CONSTRUCTION, USE OF SIDE
WALLS AND TEMPORARY ENCROACHMENTS
8.1 Temporary Construction
The plans and specifications of temporary
constructions, which are likely to interfere with
facilities or right of way provided by the Authority,
shall be submitted to the Authority for approval
showing clearly the layout, design and construction.
8.1.1 Temporary structure referred in 8.1 shall apply
to the following types of structures:
a) Structures with roof or walls made of straw,
hay, ulugrass, golpatta, hogle, darma, mat,
canvas cloth or other like materials not
adopted for permanent or continuous
occupancy.
b) Site-work sheds, truck-runways, trestles, foot-
bridges, etc.
8.2 For detailed information regarding fire safety
aspects in respect of construction, location, maintenance
and use of temporary structures [mentioned in 8.1.1(a)]
including PANDALS used by public for outdoor
assembly, reference may be made to good practice
[7(5)].
8.3 Special permits shall be obtained for the storage
of the materials on side walks and highways. It shall
be ensured that the material dump or the storage shed
does not create a traffic hazard, nor it shall interfere
with the free flow of the pedestrian traffic. Special
permits shall also be obtained for the use of water
and electricity from the public facilities. Whenever
such utilities are made use of, adequate safety
precautions regarding drainage and elimination of
contamination and hazards from electricity shall be
taken.
8.4 In order to ensure safety for the adjoining property,
adequate temporary protective guards are to be
provided. In case these protective devices project
beyond the property, the consent of the Authority and
that of the owner of the adjoining property shall be
obtained.
9 TESTING
9.1 Tests
No structure, temporary support, scaffolding or any
construction equipment during the construction or
demolition of any building or structure shall be loaded
beyond the allowable loads and working stresses as
provided for in Part 6 'Structural Design' {see also
good practice [7(6)]}.
9.1.1 Whenever any doubt arises about the
structural adequacy of a scaffolding, support or any
other construction equipment, it shall be tested to
two and a half times the superimposed dead and
imposed loads to which the material or the
equipment is subjected to and the member/material
shall sustain the test load without failure if it is to
be accepted.
9.2 Notwithstanding the test mentioned above, if any
distress in any member is visible, the member shall be
rejected.
10 INSPECTION AND RECTIFICATION OF
HAZARDOUS DEFECTS
10.1 Inspection
The Authority shall inspect the construction equipment
and if during the inspection, it is revealed that unsafe/
illegal conditions exist, the Authority shall intimate
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
23
the owner and direct him to take immediate remedial
measures to remove the hazard/violation.
10.2 Rectification
The owner shall proceed to rectify the defect,
hazardous condition or violation within 24 h of the
receipt of the notice from the Authority. The
Authority shall have full powers to rectify the unsafe
condition and all expenses incurred in this connection
is payable by the owner of the property. Illegal
encroachments and non-payment of money due, in
respect of the rectification of unsafe conditions may
vest a lien on the property with the Authority {see
also Part 2 'Administration').
10.3 When the strength and adequacy of any scaffold
or other construction equipment is in doubt or when
any complaint is made, the Authority shall get the same
inspected before use.
11 FOUNDATIONS
11.1 General
The distribution of the supporting foundation shall be
such as to avoid any harmful differential settlement of
the structure. The type and design of the foundation
adopted shall ensure safety to workmen during
construction and residents of the neighbouring
property. Sufficient care shall be taken in areas, where
withdrawal of ground water from surrounding areas
could result in damages to such foundations. During
the construction of the foundation, it shall be ensured
that the adjoining properties are not affected by any
harmful effects.
11.2 Adjoining Properties
The person causing excavation shall, before starting
the work, give adequate notices in writing to the
owner of the adjoining properties, safety of which is
likely to be affected due to excavation. After having
given such notices, wherein details regarding the type
of protective works that are anticipated to be
incorporated in the excavation are shown, written
permission shall be obtained for such excavation from
the adjoining property owners. Where necessary, the
person causing excavation shall make adequate
provision to protect the safety of adjacent property.
If on giving such notices and the precautionary
measures having been approved by the Authority, the
adjoining property owner still refuses to give
necessary facilities to the person causing excavation
for protecting/providing both temporary and
permanent supports to such property, the
responsibility for any damage to the adjoining
property shall be that of the adjoining property owner.
The person causing excavation shall be absolved of
responsibility for any loss of property or life in the
adjoining property.
In driven piles vibration is set up which may cause
damage to adjoining structures or service lines
depending on the nature of soil condition and the
construction standard of such structures and service
lines. Possible extent of all such damages shall be
ascertained in advance, and operation and mode of
driving shall be planned with appropriate measures to
ensure safety.
Where in the vicinity of a site where bored or driven
piling works are to be carried out there are old
structures which are likely to be damaged, tell-tales
shall be fixed on such structures to watch their
behaviour and timely precautions taken against any
undesirable effect.
11.3 During construction, inspection shall be made by
the engineer-in-charge to ensure that all protective
works carried out to safe-guard the adjoining property
are sufficient and in good order to ensure safety {see
Part 2 'Administration').
11.4 Before carrying out any excavation work/pile
driving, the position, depth and size of underground
structures, such as water pipes, mains, cables or other
services in the vicinity to the proposed work, may be
obtained from the Authority to prevent accidents to
workmen engaged in excavation work and calamities
for the general public.
Prior to commencement of excavation detailed data of
the type of soils that are likely to be met with during
excavation shall be obtained and the type of protective
works by way of shoring timbering, etc, shall be
decided upon for the various strata that are likely to
be encountered during excavation. For detailed
information regarding safety requirements during
excavation reference may be made to good practice
[7(7)].
12 GENERAL REQUIREMENTS AND COMMON
HAZARDS DURING EXCAVATION
12.1 Location of Machinery and Tools
Excavating machinery consisting of both heavy and
light types shall be kept back from the excavation
site at a distance which would be safe for such type
of equipment. Heavy equipment, such as excavating
machinery and road traffic shall be kept back from
the excavated sites at a distance of not less than the
depth of trench or at least 6 m for trench deeper than
6 m. Care shall also be taken to keep excavating tools
and materials far away from the edge of trench to
prevent such items being inadvertently knocked into
the trench.
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NATIONAL BUILDING CODE OF INDIA
12.2 Excavated Materials
Excavated materials shall be kept back from the edges
of the trench to provide clear berm of safe width. Where
this is not feasible, the protective works designed for
the trenches shall take into consideration, the additional
load due to overburden of materials.
12.2.1 Other Surcharges
Proximity of buildings, piles of lumber, crushed rocks,
sand and other constructional materials, large trees,
etc, may impose surcharges on the side of the trench
to cause sliding, etc. Under these conditions additional
protective works shall be provided to support the sides
of the trench.
12.3 Type of Strata
Adequate precautions, depending upon the type of
strata met with during excavation (like quick sand,
loose fills and loose boulder) shall be taken to protect
the workmen during excavation. Effect of climatic
variations and moisture content variations on the
materials under excavation shall be constantly watched
and precautions taken, where necessary, immediately
to prevent accidents at work site.
12.4 Overhang and Slopes
During any excavation, sufficient slopes to excavated
sides by way of provision of steps or gradual slopes
shall be provided to ensure the safety of men and
machine working in the area.
12.5 Blasting for foundation of building is prohibited
unless special permission is obtained from the
Authority. Where blasting technique has to be resorted
to, prior inspection for the stability of slopes shall be
carried out. After blasting, overhangs or loose boulders
shall be cleared by expert workers carrying out blasting
prior to continuation of the excavation by normal
working parties.
12.5.1 Burrowing or mining or what is known as
'gophering' shall not be allowed. In any trench where
such methods have been followed, the cavities felt shall
be eliminated by cutting back the bare slope before
removing any further material from the section of the
trench.
12.6 Health Hazards
Where gases or fumes are likely to be present in
trenches, sufficient mechanical ventilation, to protect
the health and safety of persons working there, shall
be provided. If necessary, the personnel working there,
shall be provided with respiratory protective equipment
when work in such unhealthy conditions has to be
carried out. The precautionary measures provided shall
be inspected by the local health authorities prior to
commencement of the work.
12.7 Safety of Materials
Materials required for excavation, like ropes, planks
for gangways and walkways, ladders, etc, shall be
inspected by the engineer-in-charge who shall ensure
that no accident shall occur due to the failure of such
materials (see Part 5 'Building Materials').
12.8 Fencing and Warning Signals
Where excavation is going on, for the safety of public
and the workmen, fencing shall be erected, if there is
likelihood of the public including cattle frequenting
the area. Sufficient number of notice boards and danger
sign lights shall be provided in the area to avoid any
member of public from inadvertently falling into the
excavation. When excavations are being done on roads,
diversion of the roads shall be provided with adequate
notice board and lights indicating the diversion well
ahead. Where necessary, recourse may be had
for additional precautionary measures by way of
watchmen to prevent accident to the general public,
especially during hours of darkness.
12.9 Effect of Freezing and Thawing
Due to expansion of water when freezing, rock
fragments, boulders, etc, are frequently loosened.
Therefore, the side walls of the excavation shall be
constantly watched for signs of cracks during a thaw.
When depending in whole or in part on freezing to
support the side walls, great care shall be taken during
thaws to provide suitable bracing or remedy the
condition by scaling of the loose material from the
sides.
12.10 Vibrations from Nearby Sources
Vibration due to adjacent machinery, vehicles, rail-
roads, blasting, piling and other sources require
additional precautions to be taken.
12.11 Precautions While Using Petroleum Powered
Equipment
At the site of excavation, where petroleum powered
equipment is used, petroleum vapours are likely to
accumulate at lower levels and may cause fire
explosion under favourable circumstances. Care
should, therefore, be taken to avoid all sources of
ignition in such places.
13 PILING AND OTHER DEEP FOUNDATIONS
13.1 General
13.1.1 Safety Programme
All operations shall be carried out under the immediate
charge of a properly qualified and competent foreman
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
25
who shall also be responsible for the safety
arrangements of the work.
13.1.2 For work during night, lighting of at least 100
lux intensity shall be provided at the work site.
13.1.3 Every crane driver or hoisting appliance
operator shall be competent to the satisfaction of the
engineer-in-charge and no person under the age of 21
years should be in-charge of any hoisting machine
including any scaffolding winch, or give signals to
operator.
13.1.4 Working in compressed air, in case of deep
foundations, requires several precautions to be
observed to safeguard the workmen against severe
hazards to life, compressed air disease and related
ailments. For detailed information regarding safety
requirements, reference may be made to good practice
[7(8)].
13.2 Piling Rig
13.2.1 Pile drivers shall not be erected in dangerous
proximity to electric conductors. If two pile drivers
are erected at one place these shall be separated by a
distance at least equal to the longest leg in either rig.
13.2.2 The frame of any rig shall be structurally safe
for all anticipated dead, live or wind loads. Whenever
there is any doubt about the structural strength, suitable
test shall be carried out by the foreman and the results
of the test recorded. No pile driving equipment shall
be taken into use until it has been inspected and found
to be safe.
13.2.3 Pile drivers shall be firmly supported on heavy
timber sills, concrete beds or other secure foundation.
If necessary, to prevent danger, pile drivers shall be
adequately guyed.
When the rig is not in use, extra precautionary measures
for stability, such as securing them with minimum four
guys, shall be adopted to prevent any accidents due to
wind, storm, gales and earthquake.
13.2.4 Access to working platforms and the top pulley
shall be provided by ladders. Working platforms shall
be protected against the weather.
13.2.4.1 In tall driven piling rigs or rigs of similar
nature where a ladder is necessary for regular use, the
ladder shall be securely fastened and extended for the
full height of the rig.
13.2.5 Exposed gears, fly wheels, etc, shall be fully
enclosed.
13.2.6 Pile driving equipment in use shall be inspected
by a competent engineer at regular intervals not
exceeding three months, A register shall be maintained
at the site of work for recording the results of such
inspected pile lines and pulley blocks shall be inspected
by the foreman before the beginning of each shift, for
any excess wear or any other defect.
13.2.6.1 Defective parts of pile drivers, such as
sheaves, mechanism slings and hose shall be repaired
by only competent person and duly inspected by
foreman-in-charge of the rig and the results recorded
in the register. No steam or air equipment shall be
repaired while it is in operation or under pressure.
Hoisting ropes on pile drivers shall be made of
galvanized steel.
13.2.7 Steam and air lines shall be controlled by easily
accessible shut-off valves. These lines shall consist of
armoured hose or its equivalent. The hose of steam
and air hammers shall be securely lashed to the hammer
so as to prevent it from whipping if a connection breaks.
Couplings of sections of hose shall be additionally
secured by ropes or chains.
13.2.8 When not in use the hammer shall be in dropped
position and shall be held in place by a cleat, timber or
any other suitable means.
13.2.9 For every hoisting machine and for every
chain rig hook, shackle, swivel and pulley block used
in hoisting or as means of suspension, the safe
working loads shall be ascertained. In case of doubt,
actual testing shall be carried out and the working
load shall be taken as half of the tested load. Every
hoisting machine and all gears referred to above shall
be plainly marked with the safe working load. In case
of a hoisting machine having a variable safe working
load, each safe working load together with the
conditions under which it is applicable shall be clearly
indicated. No part of any machine or any gear shall
be loaded beyond the safe working load except for
the purpose of testing.
13.2.10 Motor gearing, transmission, electrical wiring
and other dangerous parts of hoisting appliances should
be provided with efficient safe guards. Hoisting
appliances shall be provided with such means as will
reduce, to the minimum, the risk of accidental descent
of the load and adequate precautions shall be taken to
reduce to the minimum, the risk of any part of
suspended load becoming accidentally displaced.
When workers are employed on electrical installations
which are already energized, insulating mats and
wearing apparel, such as gloves, etc, as may be
necessary, shall be provided. Sheaves on pile drivers
shall be guarded so that workers may not be drawn
into them.
13.2.10.1 When loads have to be inclined:
a) they shall be adequately counter-balanced,
and
26
NATIONAL BUILDING CODE OF INDIA
b) the tilting device shall be secured against
slipping.
13.2.1 1 Adequate precautions shall be taken to prevent
a pile driver from overturning if a wheel breaks.
13.2.12 Adequate precautions shall be taken by
providing stirrups or by other effective means, to
prevent the rope from coming out of the top pulley or
wheel.
13.2.13 Adequate precautions shall be taken to prevent
the hammer from missing the pile.
13.2.14 If necessary, to prevent danger, long piles and
heavy sheet piling should be secured against falling.
13.2.15 Wherever steam boilers are used, the safety
regulations of boilers shall be strictly followed and
safety valves shall be adjusted to 7N/cm 2 in excess of
working pressure accurately.
13.2.16 Where electricity is used as power for piling
rig, only armoured cable conforming to the relevant
Indian Standard shall be used.
13.2.17 All checks as given in the Indian Standards
and any manuals issued by the manufacturers shall be
carried out.
13.3 Operation of Equipment
13.3.1 Workers employed in the vicinity of pile drivers
shall wear helmets conforming to accepted standards
[7(9)].
13.3.2 Piles shall be prepared at a distance at least
equal to twice the length of the longest pile from the
pile driver.
13.3.3 Piles being hoisted in the rig should be so slung
that they do not have to be swung round, and may not
inadvertently, swing or whip round. A hand rope shall
be fastened to a pile that is being hoisted to control its
movement. While a pile is being guided into position
in the leads, workers shall not put their hands or arms
between the pile and the inside guide or on top of the
pile, but shall use a rope for guiding.
13.3.4 Before a good pile is hoisted into position it
shall be provided with an iron ring or cap over the
driving end to prevent brooming. When creosoted
wood piles are being driven, adequate precautions shall
be taken, such as the provision of personal protective
equipment and barrier creams, to prevent workers
receiving eye or skin injuries from splashes of creosote.
13.3.5 When piles are driven at an inclination to the
vertical, if necessary, to prevent danger, these should
rest in a guide.
13.3.6 No steam or air shall be blown down until all
workers are at a safe distance.
14 WALLS
14.1 General
Depending on the type of wall to be constructed the
height of construction per day shall be restricted to
ensure that the newly constructed wall does not come
down due to lack of strength in the lower layers.
Similarly, in long walls adequate expansion/crumple
joints shall be provided to ensure safety.
14.2 Scaffold
Properly designed and constructed scaffolding built by
competent workmen shall be provided during the
construction of the walls to ensure the safety of workers.
The scaffolding may be of timber, metal or bamboo
sections and the materials in scaffolding shall be
inspected for soundness, strength, etc, at site by the
engineer-in-charge prior to erection of scaffolds.
Steel scaffolds intended for use in normal building
construction work shall conform to accepted standards
[7(10)]. Bamboo and timber scaffolds shall be properly
tied to the junctions with coir ropes of sufficient strength
or mechanical joints to ensure that joints do not give
way due to the load of workmen and material. Joining
the members of scaffolds only with nails shall be
prohibited as they are likely to get loose under normal
weathering conditions. In the erection or maintenance
of tall buildings, scaffoldings shall be of non-
combustible material especially when the work is being
done on any building in occupation. After initial
construction of the scaffolding, frequent inspections of
scaffolding. The platforms, gangways and runways
provided on the scaffoldings shall be of sufficient
strength and width to ensure safe passage for the
workmen working on the scaffolding. The joints
provided in these gangways, platforms, etc, shall be such
as to ensure a firm foot-hold to the workmen. Where
necessary, cross bars shall be provided to the full width
of gangway or runway to facilitate safe walking. For
detailed information regarding safety requirements for
erection, use and dismantling of scaffolds, reference may
be made to good practice [7(1 1)].
14.2.1 The engineer-in-charge shall ensure by frequent
inspections that gangways of scaffolding have not
become slippery due to spillage of material. Loose
materials shall not be allowed to remain on the
gangways. Where necessary, because of height or
restricted width, hand-rails shall be provided on both
sides. Workers shall not be allowed to work on the
scaffolding during bad weather and high winds.
14.2.2 In the operations involved in the erection or
maintenance of outside walls, fittings, etc, of tall
buildings, it is desirable to use one or more net(s) for
the safety of the workmen when the workmen are
required to work on scaffoldings.
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
27
14.3 Ladders
All ladders shall be constructed of sound materials and
shall be capable of carrying their intended loads safely.
The ladders shall have not only adequate strength but
rigidity as well. If a ladder shows tendency to spring,
a brace shall be attached to its middle and supported
from some other non-yielding fixed object. No ladder
having a missing or defective rung or one which
depends for its support solely on nails, shall be used.
Ladders shall not be used as guys, braces or skids or
for any other purpose for which they are not intended.
They shall not be used in horizontal position as
runways. They shall not be overcrowded. Wherever
possible, ladders shall not be spliced. Where splicing
is unavoidable, it shall be done only under the
supervision of engineer-in-charge. Ladders leading to
landings or walkways shall extend at least one metre
above the landing and shall be secured at the upper
end. To prevent slipping, a ladder shall be secured at
the bottom end. If this cannot be done, a person shall
be stationed at the base whenever it is in use. As a
further precautions, the pitch at which a lean-to-ladder
is used shall be such that the horizontal distance of its
foot from the vertical plane of its top shall be not more
than one quarter of its length. If the surface of the floor
on which the ladder rests is smooth or sloping, the
ladder shall be provided with non-slip bases. If the use
of a ladder is essential during strong winds, it shall be
securely lashed in position. No ladder shall be placed
or leant against window pane, sashes or such other
unsafe or yielding objects, nor placed in front of doors
opening towards it. If set up in driveways, passageways
or public walkways, it shall be protected by suitable
barricades. When ascending or descending, the user
shall face the ladder, use both his hands and place his
feet near the ends of the rungs rather than near the
middle. It is dangerous to lean more than 30 cm to side
in order to reach a larger area from a single setting of
the ladder. Instead, the user shall get down and shift
the ladder to the required position.
Metal ladders shall not be used around electrical
equipment or circuits of any kind where there is a
possibility of coming in contact with the current. Metal
ladders shall be marked with signs reading 'CAUTION:
DO NOT USE NEAR ELECTRICAL EQUIPMENT' .
Wooden ladders shall be inspected at least once in a
month for damage and deterioration. Close visual
inspection is recommended in preference to load
testing. This condition is particularly applicable to rope
and bamboo ladders wherein fraying of ropes and
damage to bamboo is likely to occur due to materials
falling on them. When a ladder has been accidentally
dropped it shall be inspected by the engineer-in-charge
prior to re-use. Overhead protection shall be provided
for workmen under ladder. For detailed information
regarding safety requirements for use of ladders,
reference may be made to good practice [7(12)].
14.4 Opening in Walls
Whenever making of an opening in the existing wall
is contemplated, adequate supports against the collapse
or cracking of the wall portion above or roof or
adjoining walls shall be provided.
14.4.1 Guarding of Wall Openings and Holes
Wall opening barriers and screens shall be of such
construction and mounting that they are capable of
withstanding the intended loads safely. For detailed
information reference may be made to good practice
[7(13)]. Every wall opening from which there is a drop
of more than 1 200 mm shall be guarded by one of the
following:
a) Rail, roller, picket fence, half door or
equivalent barrier — The guard may be
removable but should preferably be hinged
or otherwise mounted so as to be conveniently
replaceable. Where there is danger to persons
working or passing below on account of the
falling materials, a removable toe board or
the equivalent shall also be provided. When
the opening is not in use for handling
materials, the guards shall be kept in position
regardless of a door on the opening. In
addition, a grab handle shall be provided on
each side of the opening. The opening should
have a sill that projects above the floor level
at least 25 mm.
b) Extension platform into which materials may
be hoisted for handling, shall be of full length
of the opening and shall have side rails or
equivalent guards.
14.4.2 Every chute wall opening from which there is
a drop of more than 1 200 mm shall be guarded by
one or more of the barriers specified in 14.4.1 or as
required by the conditions.
14.5 Projection from Walls
Whenever projections cantilever out of the walls,
temporary formwork shall be provided for such
projections and the same shall not be removed till walls
over the projecting slabs providing stability load
against overturning are completely constructed.
15 COMMON HAZARDS DURING WALLING
15.1 Lifting of Materials for Construction
Implements used for carrying materials to the top of
scaffoldings shall be of adequate strength and shall
not be overloaded during the work. Where workmen
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NATIONAL BUILDING CODE OF INDIA
have to work below scaffoldings or ladder, overhead
protection against the falling materials shall be
provided. Care shall be taken in carrying large bars,
rods, etc, during construction of the walls to prevent
any damage to property or injury to workmen.
15.2 Haulage of Materials
15.2.1 In case of precast columns, steel beams, etc,
proper precautions shall be taken to correctly handle,
use and position them with temporary arrangement of
guys till grouting of the base.
15.2.2 Manila or sisal rope shall not be used in rainy
season for hoisting of heavy materials as they lose their
strength with alternate wetting and drying.
15.3 Electical Hazards
No scaffolding, ladder, working platform, gangway
runs, etc, shall exist within 3 m from any uninsulated
electric wire.
15.4 Fire Hazards
Gangways and the ground below the scaffolding shall
be kept free from readily combustible materials
including waste and dry vegetation at all times.
15.4.1 Where extensive use of blow torch or other
flame is anticipated scaffoldings, gangways, etc, shall
be constructed with fire resistant materials. A portable
dry powder extinguisher of 3 kg capacity shall be kept
handy.
15.5 Mechanical Hazards
Care shall be taken to see that no part of scaffolding or
walls is struck by truck or heavy moving equipment
and no materials shall be dumped against them to
prevent any damage. When such scaffoldings are in or
near a public thoroughfare, sufficient warning lights
and boards shall be provided on the scaffoldings to
make them clearly visible to the public.
15.6 Fragile Materials
During glazing operations, adequate precautions shall
be taken to ensure that the fragments of fragile
materials do not cause any injury to workmen or
general public in that area by way of providing
covering to such material, side protection at work site,
etc.
16 ROOFING
16.1 Prevention of accidental falling of workmen
during the construction of roofs shall be ensured by
providing platforms, catch ropes, etc. If the materials
are to be hoisted from the ground level to the roof level,
adequate precautions shall be taken by way of correct
technique of handling, hoists of sufficient strength to
cater for the quantity of stores to be hoisted and
prevention of overloading such hoists or buckets,
prevention of overturning of hoists or buckets. Where
in a multi-storeyed building, the floor of one storey is
to be used for storage of materials for the construction
of roofs, it shall be ensured that the quantum of stores
kept on the floor along with the load due to personnel
engaged in the construction work shall not exceed the
rated capacity of the floors.
16.2 While roofing work is being done with corrugated
galvanized iron or asbestos cement sheets, it shall be
ensured that joints are kept secured in position and do
not slip, thus causing injury to workmen. Workers
should not be allowed to walk on asbestos cement
sheets but should be provided with walking boards.
While working with tiles, it shall be ensured that they
are not kept loose on the roof site resulting in falling
of tiles on workmen in lower area. In slopes of more
than 30° to the horizontal, the workmen shall use
ladders or other safety devices to work on the roof.
16.3 If any glass work is to be carried out in the roof,
it shall be ensured that injury to passerby due to
breaking of glass is prevented. During wet conditions,
the workmen shall be allowed to proceed to work on a
sloping roof, only if the engineer-in-charge has
satisfied himself that the workmen are not likely to
slip due to wet conditions.
16.4 Flat Roof
In any type of flat roof construction, any formwork
provided shall be properly designed and executed to
ensure that it does not collapse during construction.
During actual construction of roof, frequent inspection
of the formwork shall be carried out to ensure that no
damage has occurred to it.
16.5 While using reinforcement in roofs, it shall be
ensured that enough walking platforms are provided
in the reinforcement area to ensure safe walking to the
concreting area. Loose wires and unprotected rod ends
shall be avoided.
16.6 Guarding of Floor Openings and Floor Holes
16.6.1 Every temporary floor opening shall have
railings, or shall be constantly attended by someone.
Every floor hole into which persons can accidentally
fall shall be guarded by either:
a) a railing with toe board on all exposed sides,
or
b) a floor hole cover the adequate strength and
it should be hinged in place. When the cover
is not in place, the floor hole shall be
constantly attended by some one or shall be
protected by a removable railing.
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
29
16.6.2 Every stairway floor opening shall be guarded
by a railing on all exposed sides, except at entrance to
stairway. Every ladder way floor opening or platform
shall be guarded by a guard railing with toe board on
all exposed sides (except at entrance to opening), with
the passage through the railing either provided with a
swinging gate or so offset that a person can not walk
directly into the opening.
16.6.3 Guarding of Open-Side Floors and Platform
Every open-sided floor or platform 1 200 mm or more
above adjacent floor or ground level shall be guarded
by a railing (or the equivalent) or all open sides, except
where there is entrance to ramp, stair-way, or fixed
ladder. The railing shall be provided with a toe board
beneath the open sides wherever:
a) persons may pass;
b) there is moving machinery; or
c) there is equipment with which falling
materials could create a hazard.
For detailed information, reference may be made to
good practice [7(13)].
17 ADDITIONAL SAFETY REQUIREMENTS
FOR ERECTION OF CONCRETE FRAMED
STRUCTURES (HIGH-RISE BUILDINGS)
17.1 Handling of Plant
17.1.1 Mixers
17.1.1.1 All gears, chains and rollers of mixers shall
be properly guarded. If the mixer has a charging skip
the operator shall ensure that the workmen are out of
danger before the skip is lowered. Railings shall be
provided on the ground to prevent anyone walking
under the skip while it is being lowered.
17.1.1.2 All cables, clamps, hooks, wire ropes, gears
and clutches, etc, of the mixer, shall be checked and
cleaned, oiled and greased, and serviced once a week.
A trial run of the mixer shall be made and defects shall
be removed before operating a mixer.
17.1.1.3 When workmen are cleaning the inside of the
drums, and operating power of the mixer shall be
locked in the off position and all fuses shall be removed
and a suitable notice hung at the place.
17.1.2 Cranes
17.1.2.1 Crane rails where used shall be installed on
firm ground and shall be properly secured. In case of
tower cranes, it shall be ensured that the level difference
between the two rails remains within the limits
prescribed by the manufacturer to safeguard against
toppling of the crane.
17.1.2.2 Electrical wiring which can possibly touch
the crane or any member being lifted shall be removed,
or made dead by removing the controlling fuses and
in their absence controlling switches.
17.1.2.3 All practical steps shall be taken to prevent
the cranes being operated in dangerous proximity to a
live overhead power line. In particular, no member of
the crane shall be permitted to approach within the
minimum safety distances as laid down in 4.23(a).
If it becomes necessary to operate the cranes with
clearances less than those specified above, it shall be
ensured that the overhead power lines shall invariably
be shut off during the period of operation of cranes.
Location of any underground power cables in the area
of operation shall also be ascertained and necessary
safety precautions shall be taken.
17.1.2.4 Cranes shall not be used at a speed which
causes the boom to swing.
17.1.2.5 A crane shall be thoroughly examined at least
once in a period of 6 months by a competent person
who shall record a certificate of the check.
17.1.2.6 The operator of the crane shall follow the safe
reach of the crane as shown by the manufacturer.
17.1.2.7 No person shall be lifted or transported by
the crane on its hook or boom.
17.1.2.8 Toe boards and limit stops should be provided
for wheel barrows on the loading/unloading platforms.
Material should be loaded securely with no projections.
17.1.2.9 Concrete buckets handled by crane or
overhead cableway shall be suspended from deep
throated hooks, preferably equipped with swivel and
safety latch. In the concrete buckets, both bottom drop
type and side drop type, closing and locking of the
exit door of the bucket shall always be checked by the
man-in-charge of loading concrete in the bucket to
avoid accidental opening of the exit door and
consequent falling of concrete.
17.1.2.10 Interlocking or other safety devices should
be installed at all stopping points of the hoists. The
hoists shaft way should be fenced properly.
17.1.2.11 When the bucket or other members being
lifted are out of sight of the crane operator, a signalman
shall be posted in clear view of the receiving area and
the crane operator.
17.1.2.12 A standard code of hand signals shall be
adopted in controlling the movements of the crane, and
both the driver and the signaler shall be thoroughly
familiar with the signals.
The driver of the crane shall respond to signals only
from the appointed signaler but shall obey stop signal
at any time no matter who gives it.
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NATIONAL BUILDING CODE OF INDIA
17.1.2.13 If a traveling gantry crane is operating over
casting beds, a warning signal which sounds
automatically during travel should be provided to avoid
accidents to workmen crossing or standing in the path
of the moving loads.
1 7.1.3 Trucks
When trucks are being used on the site, traffic problems
shall be taken care of. A reasonably smooth traffic
surface shall be provided. If practicable, a loop road
shall be provided to permit continuous operation of
vehicles and to eliminate their backing. If a continuous
loop is not possible, a turnout shall be provided.
Backing operations shall be controlled by a signalman
positioned so as to have a clear view of the area behind
the truck and to be clearly visible to the truck driver.
Movement of workmen and plant shall be routed to
avoid crossing, as much as possible, the truck lanes.
17.1.4 Concrete Pumps (Air Compressor Operated)
Safety requirements in accordance with good practice
[7(14)] shall be followed.
17.2 Formwork
17.2.1 Formwork shall be designed after taking into
consideration spans, setting temperature of concrete,
dead load and working load to be supported and safety
factor for the materials used for formwork { see also
good practice [7(6)] }.
17.2.2 All timber formwork shall be carefully
inspected before use and members having cracks and
excessive knots shall be discarded.
17.2.3 As timber centering usually takes an initial set
when vertical load is applied, the design of this
centering shall make allowance for this factor.
17.2.4 The vertical supports shall be adequately braced
or otherwise secured in position that these do not fall
when the load gets released or the supports are
accidently hit.
17.2.5 Tubular steel centering shall be used in
accordance with the manufacturer's instructions. When
tubular steel and timber centering is to be used in
combination necessary precautions shall be taken to
avoid any unequal settlement under load.
17.2.6 A thorough inspection of tubular steel centering
is necessary before its erection and members showing
evidence of excessive resting, kinks, dents or damaged
welds shall be discarded. Buckled or broken members
shall be replaced. Care shall also be taken that locking
devices are in good working order and that coupling
pins are effectively aligned to frames.
17.2.7 After assembling the basic unit, adjustment
screws shall be set to their approximate final adjustment
and the unit shall be level and plumb so that when
additional frames are installed the tower shall be in
level and plumb. The centering frames shall be tied
together with sufficient braces to make a rigid and solid
unit. It shall be ensured that struts and diagonals braces
are in proper position and are secured so that frames
develop full load carrying capacity. As erection
progresses, all connecting devices shall be in place and
shall be fastened for full stability of joints and units.
17.2.8 In case pf timber posts, vertical joints shall be
properly designed. The connections shall normally be
with bolts and nuts. Use of rusted or spoiled threaded
bolts and nuts shall be avoided.
17.2.9 Unless the timber centering is supported by a
manufacturer' s certificate about the loads it can stand,
centering shall be designed by a competent engineer.
17.2.10 Centering layout shall be made by a qualified
engineer and shall be strictly followed. The bearing
capacity of the soil shall be kept in view for every
centering job. The effect of weather conditions as dry
clay may become very plastic after a rainfall and show
marked decrease in its bearing capacity.
17.2.11 Sills under the supports shall be set on firm
soil or other suitable material in a pattern which assures
adequate stability for all props. Care shall be taken not
to disturb the soil under the supports. Adequate
drainage shall be provided to drain away water coming
due to rains, washing of forms or during the curing of
the concrete to avoid softening of the supporting soil
starta.
17.2.12 All centering shall be finally, inspected to
ensure that;
a) footings or sills under every post of the
centering are sound.
b) all lower adjustment screws or wedges are
sung against the legs of the panels.
c) all upper adjustment screws or heads of jacks
are in full contact with the formwork.
d) panels are plumb in both directions.
e) all cross braces are in place and locking
devices are in closed and secure position.
f) In case of CHHAJAS and balconies, the props
shall be adequate to transfer the load to the
supporting point.
17.2.13 During pouring of the concrete, the centering
shall be constantly inspected and strengthened, if
required, wedges below the vertical supports tightened
and adjustment screws properly adjusted as necessary.
Adequate protection of centering shall be secured from
moving vehicles or swinging loads.
17.2.14 Forms shall not be removed earlier than as
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
31
laid down in the specifications and until it is certain
that the concrete has developed sufficient strength to
support itself and all loads that will be imposed on it.
Only workmen actually engaged in removing the
formwork shall be allowed in the area during these
operations. Those engaged in removing the formwork
shall wear helmets, gloves and heavy soled shoes and
approved safety belts if adequate footing is not
provided above 2 m level. While cutting any tying
wires in tension, care shall be taken to prevent backlash
which might hit a workman.
17.2.14.1 The particular order in which the supports
are to be dismantled should be followed according to
the instructions of the site engineer.
17.3 Ramps and Gangways
17.3.1 Ramps and gangways shall be of adequate
strength and evenly supported. They shall either have
a sufficiently flat slope or shall have cleats fixed to the
surface to prevent slipping of workmen. Ramps and
gangways shall be kept free from grease, mud, snow
or other slipping hazards or other obstructions leading
to tripping and accidental fall of a workman.
17.3.1.1 Ramps and gangways meant for transporting
materials shall have even surface and be of sufficient
width and provided with skirt boards on open sides.
17.4 Materials Hoists
17.4.1 The hoist should be erected on a firm base,
adequately supported and secured. All materials
supporting the hoist shall be appropriately designed
and strong enough for the work intended and free from
defects.
17.4.2 The size of the drum shall match the size of
the rope. Not less than two full turns of rope shall
remain on the drum at all times. Ropes shall be securely
attached to the drum.
17.4.3 All ropes, chains and other lifting gear shall be
properly made of sound materials, free from defects
and strong enough for the work intended. They shall
be examined by a competent person who shall clearly
certify the safe working load on each item and the
system.
17.4.4 Hoistways shall be protected by a substantial
enclosure at ground level, at all access points
and wherever persons may be struck by any moving
part.
17.4.5 Gates at access points should be at least 2 m
high wherever possible/Gates shall be kept closed at
all times except when required open for immediate
movement of materials at that landing place.
17.4.6 All gates shall be fitted with electronic or
mechanical interlocks to prevent movement of the hoist
in the event of a gate being opened.
17.4.7 Winches used for hoists shall be so constructed
that a brake is applied when the control lever or switch
is not held in the operating position (dead-man's
handle).
17.4.8 The hoist tower shall be tied to a building or
structure at every floor level or at least every 3 m. The
height of the tower shall not exceed 6 m after the last
tie or a lesser height as recommended by the
manufacturer. All ties on a hoist tower shall be secured
using right angled couples.
17.4.9 The hoist shall be capable of being operated
only from one position at a time. It shall not be operated
from the cage. The operator shall have a clear view of
all levels or, if he has not, a clear and distinct system
of signalling shall be employed.
17.4.10 All hoist platform shall be fitted with guards
and gates to a height of at least 1 m, to prevent materials
rolling/falling from the platform.
17.4.11 Where materials extend over the height of the
platform guards, a frame shall be fitted and the
materials secured to it during hoisting/lowering. (Care
should be taken to ensure that neither the frame nor
materials interfere or touch any part of the hoisting
mechanism.)
17.4.12 The platform of a goods hoist shall carry a
notice stating:
a) the safe working load; and
b) that passengers shall not ride on the hoist.
17.4.13 All hoist operators shall be adequately trained
and competent, and shall be responsible for ensuring
that the hoist is not overloaded or otherwise misued.
17.4.14 All hoists shall be tested and thoroughly
examined by a competent person before use on a site,
after substantial alteration, modification or repair of
hoists, and at least every 6 months.
17.4.15 Every hoist shall be inspected at least once
each week by a competent person and a record of these
inspections kept.
17.5 Prestressed Concrete
17.5.1 In pre-stressing operations, operating,
maintenance and replacement instructions of the
supplier of the equipment shall be strictly adhered to.
17.5.2 Extreme caution shall be exercised in all
operations involving the use of stressing equipment as
wires/strands under high tensile stresses become a
lethal weapon.
17.5.3 During the jacking operation of any tensioning
32
NATIONAL BUILDING CODE OF INDIA
element(s) the anchor shall be kept turned up close to
anchor plate, wherever possible, to avoid serious
damage if a hydraulic line fails.
17.5.4 Pulling-headers, bolts and hydraulic jacks/rams
shall be inspected for signs of deformation and failure.
Threads on bolts and nuts should be frequently
inspected for diminishing cross section. Choked units
shall be carefully cleaned.
17.5.5 Care shall be taken that no one stands in line
with the tensioning elements and jacking equipment
during the tensioning operations and that no one is
directly over the jacking equipment when deflection
is being done. Signs and barriers shall be provided to
prevent workmen from working behind the jacks when
the stressing operation is in progress.
17.5.6 Necessary shields should be put up immediately
behind the prestressing jacks during stressing
operations.
17.5.7 Wedges and other temporary anchoring devices
shall be inspected before use.
17.5.8 The prestressing jacks shall be periodically
examined for wear and tear.
17.6 Erection of Prefabricated Members
17.6.1 A spreader beam shall be used wherever
possible so that the cable can be as perpendicular to
the members being lifted as practical. The angle
between the cable and the members to be lifted shall
not be less than 60°.
17.6.2 The lifting wires shall be tested for double the
load to be handled at least once in six months. The
guy line shall be of adequate strength to perform its
function of controlling the movement of members
being lifted.
17.6.3 Temporary scaffolding of adequate strength
shall be used to support precast members at
predetermined supporting points while lifting and
placing them in position and connecting them to other
members.
17.6.4 After erection of the member, it shall be guyed
and braced to prevent it from being tipped or dislodged
by accidental impact when setting the next member.
17.6.5 Precast concrete units shall be handled at
specific picking points and with specific devices.
Girders and beams shall be braced during transportation
and handled. In such a way as to keep the members
upright.
17.6.6 Methods of assembly and erection specified by
the designer, shall be strictly adhered to at site.
Immediately on erecting any unit in position, temporary
connections or supports as specified shall be provided
before releasing the lifting equipment. The permanent
structural connections shall be established at the earliest
opportunity.
17.7 Heated Concrete
When heaters are being used to heat aggregates and
other materials and to maintain proper curing
temperatures, the heaters shall be frequently checked
for functioning and precautions shall be taken to avoid
hazards in using coal, liquid, gas or any other fuel.
17.8 Structural Connections
17.8.1 When reliance is placed on bond between
precast and in-situ concrete the contact surface of the
precast units shall be suitably prepared in accordance
with the specifications.
17.8.2 The packing of joints shall be carried out in
accordance with the assembly instructions.
17.8.3 Levelling devices, such as wedges and nuts
which have no load bearing function in the completed
structure shall be released or removed as necessary
prior to integrating the joints.
17.8.4 If it becomes necessary to use electric power
for in-situ work, the same should be stepped down to
a safe level as far as possible.
17.9 General
Workmen working in any position where there is a
falling hazard shall wear safety belts or other adequate
protection shall be provided.
18 ADDITIONAL SAFETY REQUIREMENTS
FOR ERECTION OF STRUCTURAL STEEL
WORK
18.1 Safety Organization
The agency responsible for erecting the steel work
should analyze the proposed erection scheme for
safety; the erection scheme should cover safety aspects
right from the planning stage up to the actual execution
of the work.
18.2 Safety of Workpersons
18.2.1 General
While engaging persons for the job the supervisor
should check up and make sure that they are skilled in
the particular job they have to perform.
18.2.1.1 The helmets shall be worn properly and at
all times during the work and shall conform to the
accepted standards [7(9)].
18.2.1.2 The safety goggles shall be used while
performing duties which are hazardous to eye like
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
33
drilling, cutting and welding. The goggles used shall
conform to the accepted standards [7(15)] and should
suit individual workers.
18.2.1.3 The welders and gas cutters shall be equipped
with proper protective equipment like gloves, safety
boots, aprons and hand shields [see accepted standard
7( 1 5)] . The filter glass of the hand shield shall conform
to the accepted standards [7(16)] and should be suitable
to the eyes of the particular worker.
18.2.1.4 When the work is in progress, the area shall
be cordoned off by barricades to prevent persons from
hitting against structural components, or falling into
excavated trenches or getting injured by falling objects.
18.2.1.5 Warning signs shall be displayed where
necessary to indicate hazards, for example (a) '440
VOLTS*, (b) 'DO NOT SMOKE', (c) 'MEN WORKING
AHEAD', etc. Hand lamps shall be of low voltage
preferably 24 V to prevent electrical hazards.
18.2.1.6 All electrically operated hand tools shall be
provided with double earthing.
18.2.2 Anchors for guys or ties shall be checked for
proper placement. The weight of concrete in which
the anchors are embedded shall be checked for uplift
and sliding.
18.2.2.1 Split-end eye anchors shall only be used in
good, solid rock.
18.2.2.2 The first load lifted by a guy derrick shall be
kept at a small height for about 10 min and the anchors
immediately inspected for any signs or indications of
failure.
18.2.3 When a number of trusses or deep girders is
loaded in one car or on one truck, all but one being
lifted shall be tied back unless they have been tied or
braced to prevent their falling over and endangering
men unloading.
18.2.4 The erection gang shall have adequate supply
of bolts, washers, rivets, pins, etc, of the correct size.
Enough number of bolts shall be used in connecting
each piece using a minimum of two bolts in a pattern
to ensure that the joint will not fail due to dead load
and erection loads. All splice connections in columns,
crane girders, etc, shall be completely bolted or riveted
or welded as specified in the drawing before erection.
18.2.5 Girders and other heavy complicated structural
members may require special erection devices like
cleats and hooks, which can be shop assembled and
bolted or riveted or welded to the piece and may be
left permanently in the place after the work.
18.2.6 If a piece is laterally unstable when picked at
its centre, use of a balance beam is advisable, unless a
pair of bridles slings can be placed far enough apart
for them to be safe lifting points. The top flange of a
truss, girder or long beam may be temporarily
reinforced with a structural member laid flat on top of
the member and secured temporarily.
18.2.7 On deep girders, and even on some trusses, a
safety 'bar' running their full length will aid the riggers,
fitters and others employed on the bottom flange or
bottom chord to work with greater safety. This can be
a single 16 mm diameter wire rope through vertical
stiffeners of such members about one metre above the
bottom flange and clamped at the ends with wire rope
clamps. If the holes cannot be provided, short eye bolts
can be welded to the webs of the girder at intervals to
be removed and the surface chipped or ground to leave
it smooth after all work on the piece has been
completed.
18.2.8 Safety belts shall always be available at work
spot to be used whenever necessary. The rope shall be
chemically treated to resist dew and rotting. These shall
not be tied on sharp edges of steel structures. They
shall be tied generally not more than 2 m to 3 m away
from the belt.
18.2.9 On a guy derrick or climbing crane job, the
tool boxes used by the erection staff shall be moved to
the new working floor each time the rig is changed.
On a mobile crane job, the boxes shall be moved as
soon as the crane starts operating in a new area too far
away for the men to reach the boxes conveniently.
While working a tall and heavy guy derrick, it is
advisable to control tension in guys by hand winches
to avoid jerks, which may cause an accident.
18.2.10 The proper size, number and spacing of wire
rope clamps shall be used, depending on the diameter
of the wire rope. They shall be properly fixed in
accordance with good practice [7(17)]. They shall be
checked as soon as the rope has been stretched, as the
rope, especially if new, tends to stretch under the
applied load, which in turn may cause it to shrink
slightly in diameter. The clamps shall then be promptly
tightened to take care of this new condition. In addition,
the clamps shall be inspected frequently to be sure that
they have not slipped and are tight enough.
18.2.11 When the men can work safely from the steel
structure itself, this is preferable to hanging platforms
or scaffolds, as it eliminates additional operations,
which in turn, reduces the hazard of an accident.
18.2.11.1 To aid men working on floats or scaffolds,
as well as men in erection gangs, or other gangs using
small material, such as bolts and drift pins, adequate
bolt baskets or similar containers with handles of
sufficient strength and attachment to carry the loaded
containers, shall be provided.
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NATIONAL BUILDING CODE OF INDIA
18.2.11.2 The men should be trained to use such
containers, and to keep small tools gathered up and
put away in tool boxes when not in use. Material
shall not be dumped overboard when a scaffold is
to be moved. Rivet heaters shall have safe containers
or buckets for hot rivets left over at the end of the
day.
18.2.12 During the erection of tall buildings, it is
desirable to use nylon nets at a height of 3 m to 4 m to
provide safety to men. The safety net should be made
from man or machine-made fibre ropes which are UV
stablized and conforming to the acceptable standard
[7(18)].
1 8.2. 1 3 Safety Against Fire
A fire protection procedure is to be set up if there is to
be any flame cutting, burning, heating, rivetting or any
operation that could start a fire. For precautions to be
observed during welding and cutting operations,
reference may be made to good practice [7(19)].
18.2.13.1 The workers should be instructed not to
throw objects like hot rivets, cigarette stubs, etc,
around.
18.2.13.2 Sufficient fire extinguishers shall be placed
at strategic points. Extinguishers shall always be placed
in cranes, hoists, compressors and similar places.
Where electrical equipments are involved, C0 2 or dry
powder extinguishers shall be provided [see also good
practice [7(4)]}.
18.2.14 Riding on a load, tackle or runner shall be
prohibited.
18.2.15 The load shall never be allowed to rest on wire
ropes. Ropes in operation should not be touched. Wire
rope with broken strand shall not be used for erection
work. Wire ropes/manila ropes conforming to
acceptable standards [7(20)] shall be used for guying.
18.2.16 Lifting Appliances
Precautions as laid down in 17.1.2 shall be followed.
18.2.17 Slinging
18.2.17.1 Chains shall not be joined by bolting or
wiring links together. They shall not be shortened by
tying knots. A chain in which the links are locked,
stretched or do not move freely shall not be used. The
chain shall be free of kinks and twists. Proper eye
splices shall be used to attach the chain hooks.
18.2.17.2 Pulley blocks of the proper size shall be used
to allow the rope free play in the sheave grooves and
to protect the wire rope from sharp bends under load.
Idle sling should not be carried on the crane hook
alongwith a loaded sling. When idle slings are carried
they shall be hooked.
18.2.17.3 While using multilegged slings, each sling
or leg shall be loaded evenly and the slings shall be of
sufficient length to avoid a wide angle between the
legs.
18.2.18 Rivetting Operations
18.2.18.1 Handling rivets
Care shall be taken while handling rivets so that they
do not fall, strike or cause injury to men and material
below. Rivet catchers shall have false wooden bottoms
to prevent rivets from rebounding.
18.2.18.2 Rivetting dollies
Canvas, leather or rope slings shall be used for riveting
dollies. Chain shall not be used for the purpose.
18.2.18.3 Rivetting hammers
Snaps and plungers of pneumatic riveting hammers
shall be secured to prevent the snap from dropping out
of place. The nozzle of the hammer shall be inspected
periodically and the wire attachment renewed when
born.
18.2.18.4 Fire protection
The rivet heating equipment should be as near as
possible to the place of work. A pail of water shall
always be kept already for quenching the fire during
rivetting operations and to prevent fires when working
near inflammable materials.
18.2.19 Welding and Gas Cutting
18.2.19.1 For safety and health requirements in electric
gas welding and cutting operations, reference may be
made to good practice [7(21)]. The recommendations
given in 18.2.19.2 to 18.2.19.4 are also applicable.
18.2.19.2 All gas cylinders shall be used and stored
in the upright position only and shall be conveyed in
trolleys. While handling by cranes they shall be carried
in cages. The cylinders shall be marked 'full' or
'empty' as the case may be. Gas cylinders shall be
stored away from open flames and other sources of
heat. Oxygen cylinders shall not be stored near
combustible gas, oil, grease and similar combustible
materials. When the cylinders are in use, cylinder valve
key or wrench shall be placed in position. Before a
cylinder is moved, cylinder valve shall be closed. All
cylinder valves shall be closed when the torches are
being replaced or welding is stopped for some reason.
The cylinder valve and connections shall not be
lubricated.
18.2.19.3 Gas cutting and welding torches shall be
lighted by means of special lighters and not with
matches. The cables from welding equipment should
be placed in such a way that they are not run over by
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
35
traffic. Double earthing shall be provided. Before
undertaking welding operations near combustible
materials, suitable blanketing shall be provided and
fire extinguishers kept nearby. Welding shall not be
undertaken in areas where inflammable liquids and
gases are stored.
18,2.19.4 Gas lines and compressed air lines shall
be identified by suitable colour codes for easy
identification, to avoid confusion and to prevent fire
and explosion hazards.
18.3 Safety of Structure
18.3.1 General
The structure itself should be safeguarded during its
erection. The first truss of the roof system shall be
guyed on each side before the hoisting rope is detached
from it. After the subsequent trusses and roof purlins
are erected, protective guides shall be firmly
established and the required wind bracings shall be
erected to prevent the whole structure being blown over
by a sudden gale at night. Bracing and guying
precautions shall be taken on every structure until it is
complete. Guying shall be specifically done for trusses
and structural components which after their erection
form an erection device. On structures used for
temporary material storage overloading shall be
avoided.
18.3.1.1 Erection of columns shall be immediately
followed by vertical bracing between columns before
the roof structure is erected.
19 MISCELLANEOUS ITEMS
19.1 Staircase Construction
While staircase is under construction, depending on
the type of construction, namely, concrete or
brickwork, etc, suitable precautions shall be taken by
way of support, formworks, etc, to prevent any
collapse. Workmen or any other person shall not be
allowed to use such staircases till they are tested and
found fit for usage by the Authority/engineer-in-
charge. Till the permanent handrails are provided,
temporary provisions like ropes, etc, shall be provided
on staircases prior to commencement of use of such
staircases.
19.2 Lift Wells
Till the installation of the lift is completed, lift wells
shall be protected with check boards or railings together
with notice boards, danger lights, etc, to precent
persons accidentally falling into the wells. The
handrails provided shall be capable of withstanding
pressure exerted due to normal bumping of an
individual against the same.
19.3 Construction Involving the Use of Hot
Bituminous Tar Materials
19.3.1 Safety Programme
19.3.1.1 General
On all major works, an experienced and competent
foreman or supervisor shall be placed in-charge of the
work, and shall be made responsible for the strict
observance of the safety rules. He shall stock the
necessary protective equipment, fire extinguishing
equipment* first-aid kit, etc. He shall also keep a record
of the accidents taking place on any particular job, with
reasons thereof, and shall suggest suitable remedial
measures to the management for prevention thereof.
19.3.1.2 Protective covering
Workers engaged on jobs involving handling of hot
bitumen, tar, and bituminous mixtures shall use
protective wears, such as boots and gloves, preferably
of asbestos or otherwise of rubber; goggles and helmet.
No workers shall be permitted to handle such materials
without wearing the needed protective covering.
19.3.1.3 Fire fighting arrangements
When heating and handling of hot bituminous materials
is to be done in the open, sufficient stocks of clean dry
sand or loose earth shall be made available at the work
site to cope with any resultant fires. When such
materials are not available, nor are any suitable type
of fire extinguishers provided at the work site in the
open, and reliance has to be on using water for fighting
any fire, the water supply available should be in
abundance and the water shall be applied to the fire in
the form of spray. When heating of bituminous
materials is carried out in enclosed spaces, sufficient
number of properly maintained dry powder fire
extinguisher or form extinguisher conforming to
accepted standards [7(21)] shall be kept in readiness
on the work site.
19.3.2 Sprayer, Spreader/Paver
19.3.2.1 Sprayer
The sprayer shall be provided with a fire resisting
screen. The screen shall have an observation window.
Piping for hot tar and bitumen shall be adequately
insulated to protect workers from injury by burns.
Flexible piping work under positive pressure shall be
of metal which shall be adequately insulated. Workers
shall not stand facing the wind directions while
spraying hot binder, lest it may fall on them causing
burns.
19.3.2.2 Spreader/Paver
Spreaders in operation shall be protected by signals,
signs or other effective means. People should be
36
NATIONAL BUILDING CODE OF INDIA
warned against walking over hot mixture laid. Gravel
spreaders shall always keep a safe distance from
sprayer. Elevated platforms on spreaders shall be
protected by suitable railing and be provided with an
access ladder.
19.3.3 Equipment for Heating of Bitumen and Tars
19.3.3.1 Tanks, vats, kettles, pots, drums and other
vessels for heating tar, bitumen and other bituminous
materials shall be;
a) adequately resistant to damage by heat,
transportation, etc;
b) capable of holding a full load without danger
of collapse, bursting or distortion;
c) provided with a close fitting cover suitable
for smothering a fire in the vessel or
protection from rain; and
d) leak proof, and provided with suitable outlets
which can be controlled for taking out the hot
material.
19.3.3.2 Suitable indicator gauges shall be used to
ascertain level and temperature of the material in the
boiler. On no account shall workers be allowed to peep
into the boiler for this purpose. For ascertaining levels,
in small plants, dipstick may also be used.
19,3.33 Gas and oil-fired bitumen and tar kettles or
pots shall be equipped with burners, regulators and
safety devices of types approved by the Authority.
Heating appliances for vessels shall distribute the heat
uniformly over the heating surface so as to avoid
overheating. In case of bituminous mixtures using
mineral aggregates filler together with bitumen, it is
preferable to have some means for stirring as well. Only
vessels heated by electricity shall be used inside
buildings. Tar boilers shall never be used on
combustible roof.
19.3.3.4 Buckets for hot bitumen, bituminous
materials of tar shall have:
a) the bail or handle firmly secured, and
b) a second handle near the bottom for tipping.
19.3.3.5 Bitumen or tar boilers mounted on wheels
for easy transport or towing shall preferably be
provided with hand pumps for spraying purposes.
19.3.3.6 Vessels in operation shall be kept at a safe
distance from combustible materials. When vessels are
used in confined spaces, the gases, fumes and smoke
generated shall be removed by exhaust ventilation or
by forced ventilations. Vessels that are being heated
shall not be left unattended. Pieces of bituminous
material shall not be thrown into the hot vessels so as
to cause splashing. Covers shall be kept closed when
vessels are not in use. Containers shall not be filled
with hot bitumen or tar to a level that might cause
danger when they are carried or hoisted. Enough space
shall be left in vessels for expansion of binder when
heated.
19.3.3.7 Bitumen/Tar shall be kept dry and to avoid
fire due to foaming, boiler shall have a device that
prevents foam from reaching the burners or anti-
foaming agents shall be used to control the same.
Alternatively to avoid fire due to foaming, the heating
shall be at low temperature till the water entrapped, if
any, is completely evaporated. Any water present in
the boiler shall also be drained before using it for
heating binders. No open light shall be used for
ascertaining the level of binder in boilers. If a burner
goes out, the fuel supply shall be cut off and the heating
tube shall be thoroughly blown out by the fan so as to
prevent a back fire.
19.3.3.8 Cutbacks shall not be heated over an open
flame unless a water jacket is used. While they are
being heated the vessel shall be kept open.
1933.9 Piping shall not be warmed with burning rags
and instead blow-lamps or similar devices shall be used.
1933.10 Spilled bitumen or tar shall be promptly
cleaned up around boilers.
1933.11 Inspection openings shall not be opened
while there is any pressure in the boiler.
1933.12 When tanks are cleaned by steam, adequate
precautions shall be taken to prevent any built up of
pressure.
193.4 Handling Bitumen/Tar
Bitumen/tar shall not be heated beyond the temperature
recommended by the manufacturer of the product.
While discharging heated binder from the boiler,
workers shall not stand opposite to the jet so as to avoid
the possibility of hot binder falling on them. The
container shall be handled only after closing the control
valve. While handling hot bitumen/tar, workers shall
exercise scrupulous care to prevent accidental spillage
thereof. The buckets and cans in which the hot material
is carried from boiler shalL1>e checked before use to
ensure that they are intact and safe. Mops and other
applicators contaminated with bituminous materials
shall not be stored inside buildings.
193.5 Bitumen Plants
Safety requirements shall be in accordance with good
practice [7(22)].
19.4 Timber Structure
Preventive measures against hazards in work places
involving construction of timber structures shall be
taken in accordance with good practice [7(23)].
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
37
20 FINISHES
20.1 Painting, Polishing and Other Finishes
Only the quantity of paint, thinner and polish required
for the day's work should be kept at the work spot.
20.1.1 All containers of paint, thinner and polish which
are not in actual use should be closed with tight fitting
lids and kept at a safe place away from the actual work
site.
20.1.2 A 5 kg dry powder fire extinguisher conforming
to acceptable standards [7(23)] shall be kept handy.
20.1.3 Metal receptacles with pedal operated metal lids
shall be kept handy at the work site for depositing used
cotton rags/waste. The contents of such receptacles
shall be disposed off before the end of each day ' s work
at a safe place, preferably by burning under proper
supervision.
20.1.4 All containers of paint shall be removed from
the work site and deposited in the paint store before the
close of day ' s work. Used paint brushes shall be cleaned
and deposited in the store alongwith the containers.
20.1.5 Some paints/polishing and finishing materials
are injurious to the health of workmen. Adequate
protective clothing, respiratory equipment, etc, shall
be provided for the use of workmen during such
operations where necessary.
21 FRAGILE FIXTURES
21.1 It shall be ensured that sufficient number of
workmen and equipment are provided to carry the
fragile fixtures like sanitary fittings, glass panes, etc,
to prevent injury to workmen due to accidental
dropping of such fixtures.
22 SAFETY IN SPECIAL OPERATIONS
22.1 Safety in compressed airwork, drilling, blasting
and welding operations shall be in accordance with
good practice [7(25)].
23 ELECTRICAL INSTALLATIONS AND LIFTS
23.1 Temporary Electrical Wiring
23.1.1 Frayed and/or bare wires shall not be used for
temporary electrical connections during construction.
All temporary wiring shall be installed and supervised
by a competent electrician. Adequate protection shall
be provided for all electrical wiring laid on floor which
may have to be crossed over by construction machinery
or by the workmen. All flexible wiring connecting the
electrical appliances shall have adequate mechanical
strength and shall preferably be enclosed in a flexible
metal sheath. Overhead wires/cables shall be so laid
that ihey leave adequate head room.
23.1.2 All electrical circuits, other than those required
for illumination of the site at night, shall be switched
off at the close of day's work. The main switch board
from which connections are taken for lighting, power
operated machinery, etc, shall be located in an easily
accessible and prominent place. No articles of clothing
nor stores shall be kept at the back of or over the board
or anywhere near it. One 3 kg/4.5 kg C0 2 extinguisher
or one 5 kg dry powder extinguisher shall be provided
near the switch board.
23.2 Permanent Electrical Installations
Besides the fire safety measures for electrical
installations covered under 23.1, safety in electric
installations in buildings and installations of lifts shall
be in accordance with Part 8 'Building Services,
Section 2 Electrical and Allied Installations and
Section 5 Installation of Lifts and Escalators'.
24 GENERAL REQUIREMENTS
24.1 Sanitation
a) Adequate toilet facilities shall be provided for
the workmen within easy access of their place
of work. The total number to be provided shall
be not less than one per 30 employees in any
one shift.
b) Toilet facilities shall be provided from the
start of building operations, and connection
to a sewer shall be made as soon as practicable.
c) Every toilet shall be so constructed that the
occupant is sheltered from view and protected
from the weather and falling objects.
d) Toilet facilities shall be maintained in a
sanitary condition. A sufficient quantity of
disinfectant shall be provided.
e) An adequate supply of drinking water shall
be provided, and unless connected to a
municipal water supply, samples of the water
shall be tested at frequent intervals by the
Authority.
f) Washing facilities shall be installed, and when
practicable shall be installed, and when
practicable shaH be connected to municipal
water supply and shall discharge to a sewer.
g) Natural or artificial illumination shall be
provided.
24.2 Fire Protection
24.2.1 In addition to the provision of fire extinguishers,
as specified in this Part of the Code, other fire
extinguishing equipment shall also be provided and
conveniently located within the building under
construction or on the building site, as required by the
Authority.
38
NATIONAL BUILDING CODE OF INDIA
24.2.1.1 All fire extinguishers shall be maintained in
a serviceable condition at all times in accordance with
good practice [7(4)] and all necessary guidelines
regarding fire protection at workplaces followed in
accordance with good practice [7(2)].
24.2.1.2 It shall be ensured that all workmen and
supervisory staff are fully conversant with the correct
operation and use of fire extinguishers provided at the
construction site.
24.2.1.3 Telephone number of local fire brigade
should be prominently displayed near each telephone
provided at construction site.
24.2.1.4 Watch and ward services should be provided
at construction sites during holidays and nights.
24.2.2 Access shall be provided and maintained at all
times to all fire fighting equipment, including fire hose,
extinguishers, sprinkler valves and hydrants.
24.2.2.1 Approach roads for fire fighting should be
planned, properly maintained and kept free from
blockage. Width of approach road should be not less
than 5 m to facilitate fire fighting operations.
24.2.2.2 Emergency plan and fire order specifying the
individual responsibility in the event of fire should be
formulated and mock drills should be practised
periodically in case of large and important construction
sites to ensure upkeep and efficiency of fire fighting
appliances.
24.2.2.3 Periodical inspection should be carried out
to identify any hazard and proper records maintained
and follow up action taken.
24.2.2.4 Evaluation facilities and fire exits should be
provided at all locations susceptible to fire hazards.
24.2.3 Where the building plans require the installation
of fixed fire fighting equipment, such as hydrants, stand
pipes, sprinklers and underground water mains or other
suitable arrangements for provision of water shall be
installed, completed and made available for permanent
use as soon as possible, but in any case not later than
the stage at which the hydrants, etc, are required for
use as specified in 24.2.3.1 to 24.2.3.4,
24.2.3.1 A stand pipe system (landing valves),
permanent in nature shall be installed and made
available before the building has reached the height
of 15 m above the grade, and carried up with each
floor.
24.2.3.2 The standpipe (landing valve/internal fire
hydrant) and its installation shall conform to the
accepted standards [7(26)].
24.2.3.3 The standpipe shall be carried up with each
floor and securely capped at the top. Top hose outlets,
should at all times, be not more than one floor below
the floor under construction.
24.2.3.4 A substantial box, preferably of metal, should
be provided and maintained near each hose outlet. The
box should contain adequate lengths of hose to reach
all parts of the floor as well as a short branch fitted
with 12 mm or 20 mm nozzle.
24.2.4 Close liaison shall be maintained with the local
fire brigade, during construction of all buildings
above 15 m in height and special occupancies, like
educational, assembly, institutional, industrial, storage,
hazardous and mixed occupancies with any of the
aforesaid occupancies having area more than 500 m 2
on each floor.
24.2.5 It is desirable that telephone system or other
means of inter-communication system be provided
during the construction of all buildings over 15 m in
height or buildings having a plinth area in excess
of 1 000 m 2 .
24.2.6 All work waste, such as scrap timber, wood
shavings, sawdust, paper, packing materials and oily
waste shall be collected and disposed of safely at the
end of each day's work. Particular care shall be taken
to remove all waste accumulation in or near vertical
shaft openings like stairways, lift-shaft, etc.
24.2.7 An independent water storage facility shall be
provided before the commencement of construction
operations for fire-fighting purposes. It shall be
maintained and be available for use at all times,
24.2.8 Fire Cut-offs
Fire walls and exit stairways required for a building
should be given construction priority. Where fire doors,
with or without automatic closing devices, are
stipulated in the building plans they should be hung as
soon as practicable and before any significant quantity
of combustible material is introduced in the building.
24.2.8.1 As the work progresses, the provision of
permanent stairways, stairway enclosures, fire walls
and other features of the completed structure which
will prevent the horizontal and vertical spread of fire
should be ensured.
24.3 Clothing
24.3.1 It shall be ensured that the clothes worn by the
workmen be not of such nature as to increase the
chances of their getting involved in accident to
themselves or to others. As a rule, wearing of
CHADDARS or loose garments shall be prohibited.
24.3.2 Workmen engaged in processes which splash
liquid or other materials which will injure the skin shall
have enough protective clothing to cover the body.
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
39
24.3.3 Individuals engaged in work involving use of
naked flames (such as welding) shall not wear synthetic
fibre or similar clothing which increases the risk of
fire hazards.
24.4 Safety Measures Against Fall Prevention
Persons working at heights may use safety belts and
harnesses. Provision of cat-walks, wire mesh, railings
reduces chances of fall-ladder and scaffoldings,
stagings etc, should be anchored on firm footing and
should be secured and railing should be provided as
far as possible. All accesses should be barricaded to
prevent accidental fall. For details as fall prevention
reference may be made to good practice [7(27)].
24.5 Falling Materials Hazard Prevention
Preventive measures against falling materials hazards
in work places shall be taken in accordance with good
practice [7(28)].
24.6 Disposal of Debris
Preventive measures against hazards relating to
disposal of debris shall be taken in accordance with
[7(29)].
25 CONSTRUCTION MACHINERY
25.1 Specification and requirements of construction
machinery used in construction or demolition work
shall conform to accepted standards [7(30)].
25.2 For safety requirements for working with
construction machinery, reference may be made to
good practice [7(31)].
25.3 Petroleum powered air compressors, hoists,
derricks, pumps, etc, shall be so located that the
exhausts are well away from combustible materials.
Where the exhausts are pipes to outside the building
under construction, a clearance of at least 150 mm shall
be maintained between such piping and combustible
material.
SECTION 4 MAINTENANCE
MANAGEMENT, REPAIRS, RETROFITTING
AND STRENGTHENING OF BUILDINGS
26 MAINTENANCE MANAGEMENT
26.1 Maintenance management of building is the art
of preserving over a long period what has been
constructed. Whereas construction stage lasts for a
short period, maintenance continues for comparatively
very large period during the useful life of building.
Inadequate or improper maintenance adversely affects
the environment in which people work, thus affecting
the overall output. In the post construction stage the
day to day maintenance or upkeep of the building shall
certainly delay the decay of the building structure.
Though the building may be designed to be very
durable it needs maintenance to keep it in good
condition.
26.2 Terminology
For the purpose of this Section, the following
definitions shall apply.
26.2.1 Maintenance — The combination of all
technical and associated administrative actions
intended to retain an item in or restore it to a state in
which it can perform its required function.
26.2.2 Maintenance Management — The organization
of maintenance within an agreed policy. Maintenance
can be seen as a form of 'steady state' activity.
26.2.3 Building Fabric — Elements and components
of a building other than furniture and services.
26.2.4 Building Maintenance — Work undertaken to
maintain or restore the performance of the building
fabric and its services to provide an efficient and
acceptable operating environment to its users.
26.2.5 House Keeping — The routine recurring work
which is required to keep a structure in good condition
so that it can be utilized at its original capacity and
efficiency along with proper protection of capital
investment, throughout its economic life.
26.2.6 Owner — Person or body having a legal interest
in a building. This includes freeholders, leaseholders
or those holding a sub-lease which both bestows a legal
right to occupation and gives rise to liabilities in respect
of safety or building condition.
In case of lease or sub-lease holders, as far as ownership
with respect to the structure is concerned, the structure
of a flat or structure on a plot belongs to the allottee/
lessee till the allotment/lease subsists.
26.2.7 Confined Space — Space which may be
inadequately ventilated for any reason and may result
in a deficiency of oxygen, or a build-up of toxic gases,
e.g. closed tanks, sewers, ducts, closed and unventilated
rooms, and open topped tanks particularly where
heavier than air gases or vapours may be present.
26.3 Building Maintenance
26.3.1 General
Any building (including its services) when built has
certain objectives and during its total economic life, it
has to be maintained. Maintenance is a continuous
process requiring a close watch and taking immediate
remedial action. It is interwoven with good quality of
house keeping. It is largely governed by the quality of
original construction. The owners, engineers,
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NATIONAL BUILDING CODE OF INDIA
constructors, occupants and the maintenance agency
are all deeply involved in this process and share a
responsibility. Situation in which all these agencies
merge into one is ideal and most satisfactory.
There are two processes envisaged, that is, the work
carried out in anticipation of failure and the work
carried out after failure. The former is usually referred
to as preventive maintenance and the latter as corrective
maintenance. The prime objective of maintenance is
to maintain the performance of the building fabric and
its services to provide an efficient and acceptable
operating environment to its users.
26.3.1.1 Maintenance in general term can be identified
in the following broad categories.
a) Cleaning and servicing — This is largely of
preventive type, such as checking the efficacy
of rain water gutters and servicing the
mechanical and electrical installations. This
covers the house keeping also.
b) Rectification and repairs — This is also called
periodical maintenance work undertaken by,
say, annual contracts and including external
replastering, internal finishing etc,
c) Replacements — This covers major repair or
restoration such as re-roofing or re-building
defective building parts.
26.3.2 Factors Affecting Maintenance
26.3.2.1 Maintenance of the buildings is influenced
by the following factors:
a) Technical factors — These include age
of building, nature of design, material
specifications, past standard of maintenance
and cost of postponing maintenance.
b) Policy — A maintenance policy ensures that
value for money expended is obtained in
addition to protecting both the asset value and
the resource value of the buildings concerned
and owners.
c) Financial and economics factors — (see
26.9).
d) Environmental — All buildings are subject to
the effects of a variety of external factors such
as air, wind precipitation, temperature etc.
which influence the frequency and scope of
maintenance.
The fabric of building can be adversely
affected as much by the internal environment
as by the elements externally. Similar factors
of humidity, temperature and pollution should
be considered. Industrial buildings can be
subject to many different factors subject to
processes carried out within. Swimming pool
structures are vulnerable to the effects of
chlorine used in water.
e) User — The maintenance requirements of
buildings and their various parts are directly
related to the type and intensity of use they
receive.
26.3.2.2 Influence of design
The physical characteristics, the life span and the
aesthetic qualities of any building depend on the
considerations given at the design stage. All buildings,
however well designed and conscientiously built, will
require repair and renewal as they get older.
However, for better performance of the building
envelop, the following are the ways to minimize
troubles at the later stage.
a) Minimize defects during construction and
design.
b) Detail and choose materials during construction
so that the job of maintenance is less onerous.
26.3.2.2.1 In addition to designing a building for
structural adequacy, consideration should also be given
to environmental factors such as moisture, natural
weathering, corrosion and chemical action, user wear
and tear, pollution, flooding, subsidence, earthquake,
cyclones etc.
26.3.2.2.2 A list of common causes for maintenance
problems is given in Annex C for guidance. However,
no such list is likely to be entirely comprehensive.
26.3.3 Maintenance Policy
The policy should cover such items as the owner's
anticipated future requirement for the building taking
account of the building's physical performance and
its functional suitability. This may lead to decisions
regarding:
a) the present use of the building anticipating
any likely upgradings and their effect on
the life cycles of existing components or
engineering services; and
b) a change of use for the building and the effect
of any conversion work on the life cycles of
existing components or engineering services.
26.3.4 Maintenance Work Programmes
The programming of maintenance work can affect an
owner or his activities in the following ways:
a) maintenance work should be carried out at
such times as are likely to minimize any
adverse effect on output or function.
b) programme should be planned to obviate as
far as possible any abortive work.
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
41
This may arise if upgrading or conversion
work is carried out after maintenance work
has been completed or if work such as
rewiring is carried out after redecorations.
c) any delay in rectifying a defect should be kept
to a minimum only if such delay is likely to
affect output or function. The cost of
maintenance increases with shortening
response times.
d) maintenance work, completed or being
carried out should comply with all statutory
and other legal requirements.
26.3.5 Maintenance Guides
An owner responsible for a large number of buildings
may have established procedures for maintenance.
When an owner is responsible for the maintenance of
only one building or a small number of buildings, the
preparation of a guide tailored to suit each particular
building, can offer significant advantages. Such a guide
should take into account the following:
a) type of construction and residual life of the
building, and
b) environment and intensity of use (see 26.3.2).
The guide may form part of a wider manual covering
operational matters.
26.3.6 Planning of Maintenance Work
Work should take account of the likely maintenance
cycle of each building element and be planned
logically, with inspections being made at regular
intervals. Annual plans should take into account
subsequent years' programmes to incorporate items
and to prevent additional costs. It should be stressed
that the design of some buildings can lead to high
indirect costs in maintenance contracts and therefore,
careful planning can bring financial benefits. Decisions
to repair or replace should be taken after due
consideration.
26.3.7 Feed Back
26.3.7.1 Feed back is normally regarded as an
important procedure of providing information about
the behaviour of materials and detailing for the benefit
of the architect/engineer designing new buildings,
which will result in lessening maintenance costs. It is
an equally valuable source of information for
the persons responsible for maintenance. Every
maintenance organization should develop a sample
way of communicating its know how, firstly for benefit
of others in the organization and secondly for the
benefit of the building industry as a whole. There
should be frank and recorded dialogue on an on-going
basis between those who occupy and care for buildings
and those who design and construct them.
26.3.7.2 Feed back should aim at the following:
a) User satisfaction,
b) Continuous improvement, and
c) Participation by all.
26.3.7.3 Source of information
The information on feed back can be obtained from
the following:
a) Occupants,
b) Inspections,
c) Records, and
d) Discussions.
26.3.8 Means of Effecting Maintenance
26.3.8.1 Responsibility
Some maintenance work will be carried out by
the occupier of a building or by the occupier's
representative. In the case of leasehold or similar
occupation not all maintenance may be the
responsibility of occupier. Responsibility of common
areas may be clearly defined.
26.3.8.2 Maintenance work sub-divided into major
repair, restoration, periodical and routine or day-to-day
operations will be undertaken by one of the following:
a) Directly employed labour,
b) Contractors, and
c) Specialist contractors under service agreement
or otherwise.
26.3.8.3 The merits of each category for typical
maintenance work must be considered because
optimum use of resources appropriate to tasks in a
given situation is an important element of policy.
26.3.8.4 The success of contracting out depends on
the nature of the services, conditions in which
contracting is undertaken (the tendering process), how
the contract is formulated and subsequent monitoring
of service quality. The important consideration in the
decision to contract out is whether a contractor can
ensure a socially desirable quantity and quality of
service provision at, a reasonable cost to the
consumers.
26.4 Access
26.4.1 General
All maintenance activities including any preliminary
survey and inspection work require safe access and in
some situations this will have to be specially designed.
Maintenance policy, and maintenance costs, will be
much influenced by ready or difficult access to the
fabric and to building services. Special precautions and
access provisions may also need to be taken for roof
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NATIONAL BUILDING CODE OF INDIA
work or for entry into confined spaces such as ducts or
voids.
26.4.2 Access Facilities
26.4.2.1 Permanent accessibility measures should be
provided at the design stage only for all the areas for
safe and proper maintenance. It is a matter on which
those experienced in the case of the building can make
an important contribution at design stage in the interest
of acceptable maintenance costs.
26.4.2.2 A wide variety of temporary access equipment
may appropriately be provided for maintenance work,
ranging from ladders to scaffoldings or powered lift
platforms.
26.4.2.3 Wherever possible it is better to provide
permanent access facilities such as fixed barriers,
ladders, and stairways. When such permanent access
facilities are provided necessary arrangement may be
included in maintenance plans for their regular
inspection, maintenance and testing.
26.4.2.4 All personnel employed for carrying out
maintenance should be provided with the necessary
protective clothing and equipment and instructed in
its use.
26.4.2.5 When physical access is not possible in
situations such as wall cavities, drains etc, inspections
may be made with the aid of closed circuit television
or optical devices such as endoscopes.
26.4.3 Access to Confined Spaces
26.4.3.1 Ventilation
Special precautions need to be taken when entering a
confined space. Such confined spaces should be
adequately ventilated, particularly before being
entered, to ensure that they are free from harmful
concentrations of gases, vapours other airborne
substances and that the air is not deficient in oxygen.
26.4.3.2 Lighting
Good lighting is necessary in order that maintenance
work can be carried out satisfactorily. This is
particularly important in confined spaces. When
the normal lighting is inadequate it should be
supplemented by temporary installations. These
should provide general and spot illumination as
appropriate.
26.5 Records
26.5.1 General
Good records can save owners and users/occupiers
much unnecessary expense and reduce potential
hazards in exploration work when faults arise.
26.5.2 Use of Building Records
26.5.2.1 All personnel involved in the maintenance
of the building should be made aware of the existence
of the building records.
26.5.2.2 Known hazardous areas should be explicitly
marked on the records as well as being marked on
site and should be pointed out to such personnel
together with any system of work adopted for use in
such areas.
26.5.2.3 Records are of value only if they are kept up
to date and arrangements for this should be included
in any provision that may be made for records.
26.5.2.4 Records should be readily accessible for use
and the place of storage should take into account the
form of the records and the conditions needed to keep
them from damage of any kind. It is recommended
that a duplicate set of records is kept in a secure place
other than building itself and is kept up to date.
26.5.3 Following should be typical contents of the
maintenance records:
a) A brief history of property, names and
addresses of consultants and contractors.
b) Short specifications, constructional processes,
components, material finishes, hidden
features, special features etc.
c) "As built" plans and as subsequently altered
with sections, elevations and other detailed
drawings.
d) Foundation and structural plans/sections such
as concrete reinforcement drawings.
e) Detail specification of all materials incorporated,
for example, concrete mix, species and grades
of timber etc. Potentially hazardous materials
and types or methods of construction that
under some circumstances may become
hazardous may be identified.
f) Information on house keeping and routine
maintenance with details of internal and
external surfaces and decorations, schedule
of cleaning, inspection and maintenance.
g) Means of operating mechanical, electrical and
plumbing installations.
h) Description of renovations, extensions,
adaptations and repair to each elements.
j) All plant, machinery and propriety articles
including manufacturers trade literature
and instructions for installation, use and
maintenance.
k) Methods of work used in construction such
as assembly of prefabricated units.
m) All information related to fire such as:
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
43
1) Location and service arrangements of all
fire alarm and call points;
2) Location and service arrangements of all
extinguishers, hose reels and other fire
fighting installations;
3) Location of all fire compartment walls,
doors, floors and screens;
4) Location of all areas of exceptional fire
hazard;
5) Fire escape routes;
6) Details of application of any fire protection
treatment; and
7) Location details and description of any
installation for smoke control or protection
of escape routes.
n) There should be a wall chart showing at a
glance the various operations which have to
be undertaken. Line drawings of buildings are
always useful.
p) Records of security measures should be
known to authorized personnel only.
q) Where no records exist, information should
be slowly built up as it becomes available
during the course of maintenance work.
r) Use of computers for storing information may
be preferred.
26.5.4 Mechanical Records
26.5.4.1 Documentation
Documentation should record the following as
installed:
a) the location, including level if buried, of all
public service connections (for example, fuel
gas and cold water supplies) together with the
points of origin and termination, size and
materials of pipes, line pressure and other
relevant information;
b) the layout, location and extent of all piped
services showing pipe sizes, together with all
valves for regulation, isolation and other
purposes as well as the results of all balancing,
testing and commissioning data;
c) the location, identity, size and details of all
apparatus and all control equipment served
by, or associated with, each of the various
services together with copies of any test
certificates for such apparatus where
appropriate. The information with respect to
size and details may be presented in schedule
form;
d) the layout, location and extent of all air ducts
showing dampers and other equipment,
acoustic silencers, grilles, diffusers or other
terminal components. Each duct and each
terminal component should be marked with
its size, the air quantity flowing and other
relevant balancing data; and
e) the location and identity of each room or space
housing plant, machinery or apparatus.
26.5.4.2 Drawings
Drawings should record the following as installed:
a) detailed general arrangements of boiler
houses, machinery spaces, air handling plants,
tank rooms and other plant or apparatus,
including the location, identity, size and rating
of each apparatus. The information with
respect to the size and rating can be presented
in schedule form;
b) isometric or diagrammatic views of boiler
houses, plant rooms, tank rooms and similar
machinery, including valve identification
charts. It is useful to frame and mount a
copy of such drawings on the wall of the
appropriate room; and
c) comprehensive diagrams that show power
wiring and control wiring and/or pneumatic
or other control piping including size, type
or conductor or piping used and identifying
the terminal points of each.
26.5.5 Electrical Records
Documentation should record the following including
locations, as installed:
a) main and submain cables, showing origin,
route, termination, size and type of each cable;
cables providing supplies to specialist
equipment, for example, computers, should
be identified separately; and
b) lighting conduits and final subcircuit cables,
showing origin, route, termination and size
of each, together with the number and size of
cables within each conduit. The drawings
should indicate for each conduit or cable,
whether it is run on the surface or concealed,
for example, in a wall chase, in a floor screed,
cast in-situ, above a false ceiling etc.
These drawings should also indicate the locations of
lighting fittings, distribution boards, switches, draw-
in-boxes and point boxes, and should indicate circuitry:
a) location and purpose of each emergency
lighting fitting including an indication of the
circuit to which it is connected;
\>) single and three phase power conduits and
final subcircuit cables showing locations of
power distribution boards, motors, isolators,
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NATIONAL BUILDING CODE OF INDIA
starters, remote control units, socket outlets
and other associated equipment;
c) other miscellaneous equipment, conduits and
cables;
d) lightening conductor, air terminals, conductors,
earth electrodes and test clamps;
e) location of earth tapes, earth electrodes and
test points other than those in (f); and
f) cables providing earth circuits for specialist
equipment, for example computers, should be
identified separately.
Documentation should also include, when applicable.
a) distribution diagrams or schedules to show
size, type and length (to within 1 m) of each
main and submain cable, together with the
measured earth continuity resistance of each;
b) schedule of lighting fittings installed stating
location, manufacturer and type or catalogue
number together with the type or
manufacturer's reference, voltage and wattage
of the lamp installed;
c) schedule of escape and emergency lighting
fittings installed stating location,
manufacturer, type or catalogue number
together with the type or manufacturer's
reference, voltage and wattage of the lamp
installed. For battery systems the position of
the battery, its ampere hour rating and battery
system rated endurance in hours should be
stated;
d) records of smoke detectors, sprinklers, fire
precautions;
e) incoming supply details; the type of system,
voltage, phases, frequency, rated current and
short circuit level, with the details of the
supply protection and time of operation as
appropriate;
g) main switchgear details; for purpose made
equipment this should include a set of
manufacturers' drawings and the site layout;
h) transformer, capacitor and power plant
details; the leading details should be given,
for example, for transformers the V.A rating,
voltages and type of cooling; and
j) Completion certificate, according to the
Indian Electricity Act.
26.6 Inspections
26.6.1 General
Regular inspections are actual part of the procedures
for the maintenance of buildings. They are needed for
a variety of purposes and each purpose requires a
different approach if it is to be handled with maximum
economy and efficiency. A more detailed inspection
covering all parts of a building is needed to determine
what work should be included in cyclic and planned
maintenance programme.
26.6.2 Frequency of Inspection
Inspection should be carried out at the following
frequencies:
a) Routine — Continuous regular observations
should be undertaken by the building user as
part of the occupancy of building. Feed back
resulting from this type of observation should
be encouraged.
b) General — Visual inspections of main
elements should be made annually under the
supervision of suitably qualified personnel at
appropriate times.
c) Detailed — The frequency of full inspection
of the building fabric by suitably qualified
personnel should not normally exceed a 5 year
period.
26,6.2.1 Inspection schedule
The preparation of a specific schedule should be
encouraged. Once prepared, it can be used for
subsequent inspections.
26.6.3 Inspection of Engineering Services
Engineering services generally have a shorter life
expectancy than building fabric and because of their
dynamic function should be subjected to more frequent
inspections and maintenance.
26.6.3.1 Inspection of services should be carried out
for three purposes as follows:
a) to check if maintenance work is required,
b) to check if maintenance work is being
adequately carried out, and
c) for safety reasons to comply with
statutory requirements and if required,
with recommendations of other relevant
organizations.
26.6.3.2 The frequency of inspections for purpose
(a) will depend upon types of plant and system
manufacturer's recommendations and subjective
judgement. Frequencies for purpose (b) should be
carried out on an annual basis.
26.6.3.3 Method of inspection
The limited life of building services means it is
important to record their residual life so that their
replacement can be budgeted for, and inspection
methods should be arranged accordingly.
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
45
A check list of items of plant to be inspected should be
considered. Detailed specifications of how inspections
should be carried out are necessary because a simple
visual inspection is unlikely to show whether plant is
operating correctly and efficiently.
Inspections frequently necessitate the use of
appropriate instruments by competent persons. An
example of this is the inspections carried out to check
compliance with statutory requirements.
When instruments are used it is important that adequate
training is provided in the use of the instruments and
the interpretation of the results.
26.6.4 Records of all inspections should be kept.
26.6.5 Inspection Report
Inspection report may be prepared in the format as
given in Annex D.
26.7 Maintenance of Electrical Appliances
26.7.1 Planning of Maintenance Work
26.7.1.1 If the authorized person has complete
knowledge of the electrical appliances to be worked
upon, then safety will be more assured. If the person
attending to the job is not technically competent to
handle the job then more careful planning is required
before hand.
26.7.1.2 Repetitive nature of jobs involve little or no
pre-planning whereas infrequent nature of jobs may
need careful planning even if the person attending the
job is technically competent.
26.7.1.3 Planned routine maintenance will facilitate
continued safe and acceptable operation of an electrical
system with a minimum risk of breakdown and
consequent interruption of supply.
26.7.1.4 As far as the electrical equipments/
installations are concerned, it is not possible to laydown
precise recommendations for the interval between the
maintenance required. The recommendation for
frequency of maintenance in this regard from the
manufacturer is more relevant. The manufacturer
should be requested to specify minimum maintenance
frequency under specified conditions. These intervals
depend greatly upon the design of the equipment, the
duty that it is called on to perform and the environment
in which it is situated,
26.7.2 Following two types of maintenance are
envisaged.
26.7.2.1 Routine maintenance
Routine maintenance of the electrical equipments goes
alongwith the regular inspections of the equipments.
Inspections shall reveal the undue damage and excessive
wear to the various components. Examination of the,
equipment shall reveal any need for conditioning of
the contact system, lubrication and adjustment of the
mechanisms.
26.7.2.2 Post fault maintenance
When there is a breakdown in the system and certain
parts are identified for the replacement and then the
maintenance/repair of the defective part away from the
operating environment is covered under post fault
maintenance.
26.7.3 Guidelines for the Maintenance of Electrical
Appliances
26.7.3.1 Uninterrupted and hazard free functioning of
the electrical installations are the basic parameters of
maintenance. The equipment should be restored to
correct working conditions. Special attention should
be paid to the items and settings that might have been
disturbed during the operational phase. Loose and
extraneous equipment or wiring give rise to potential
safety hazards. All covers and locking arrangements
should be properly checked and secured to achieve
original degree of protection.
26.7.3.2 Guidelines to be followed for the maintenance
of electrical equipments to ensure their smooth
functioning are given in Annex E.
26.8 Operating and Maintenance Manuals
The engineering services within buildings frequently
are dynamic, involving complex systems of integrated
plant items. Operation of such plant can require detailed
knowledge and direction. Maintenance can also require
extensive information to be available. It is, therefore,
important to have suitable operating and maintenance
manuals to provide the necessary guidance. These
should be included as part of the contractual
requirements for new installations and should ideally
be prepared as reference documents for existing
installations where no such information exists.
26.9 For details on labour management concerning
building maintenance, reference shall be made to good
practice [7(32)].
26.10 For details on financial management concerning
building maintenance, reference shall be made to good
practice [7(33)].
27 PREVENTION OF CRACKS
27.1 Cracks in buildings are of common occurrence.
A building component develops cracks whenever stress
in the component exceeds its strength. Stress in a
building component could be caused by externally
applied forces, such as dead, imposed, wind or seismic
loads, or foundation settlement or it could be induced
46
NATIONAL BUILDING CODE OF INDIA
internally due to thermal movements, moisture
changes, chemical action, etc.
27.2 Cracks could be broadly classified as structural
or non-structural. Structural cracks are those which are
due to incorrect design, faulty construction or
overloading and these may endanger the safety of a
building. Extensive cracking of an RCC beam is an
instance of structural cracking. Non-structural cracks
are mostly due to internally induced stresses in building
materials and these generally do not directly result in
structural weakening. In course of time, however,
sometime non-structural cracks may, because of
penetration of moisture through cracks or weathering
action, result in corrosion of reinforcement and thus
may render the structure unsafe. Vertical cracks in a
long compound wall due to shrinkage or thermal
movement is an instance of non-structural cracking.
Non-structural cracks, normally do not endanger the
safety of a building, but may look unsightly, or may
create an impression of faulty work or may give a
feeling of instability. In some situations, cracks may,
because of penetration of moisture through them, spoil
the internal finish, thus adding to cost of maintenance.
It is, therefore, necessary to adopt measures of
prevention or minimization of these cracks.
27.3 For complete details on causes and prevention
of non-structural cracks, reference shall be made to
good practice SP 25 : 1984 'Handbook on causes and
prevention of cracks in buildings'.
28 REPAIRS AND SEISMIC STRENGTHENING
OF BUILDINGS
28.1 General Principles and Concepts
28.1.1 N on- structural/ Architectural Repairs
28.1.1.1 The buildings affected by earthquake may
suffer both non-structural and structural damages. Non-
structural repairs may cover the damages to civil and
electrical items including the services in the building.
Repairs to non-structural components need to be taken
up after the structural repairs are carried out. Care
should be taken about the connection details of
architectural components to the main structural
components to ensure their stability.
28.1.1.2 Non-structural and architectural components
get easily affected/dislocated during the earthquake.
These repairs involve one or more of the following:
a) Patching up of defects such as cracks and fall
of plaster;
b) Repairing doors, windows, replacement of
glass panes;
c) Checking and repairing electric conduits/
wiring;
d) Checking and repairing gas pipes, water pipes
and plumbing services;
e) Re-building non-structural walls, smoke
chimneys, parapet walls, etc;
f) Re-plastering of walls as required;
g) Rearranging disturbed roofing tiles;
h) Relaying cracked flooring at ground level;
and
j) Redecoration — white washing, painting, etc.
The architectural repairs as stated above do not restore
the original structural strength of structural components
in the building and any attempt to carry out only repairs
to architectural/non-structural elements neglecting
the required structural repairs may have serious
implications on the safety of the building. The damage
would be more severe in the event of the building being
shaken by the similar shock because original energy
absorption capacity of the building would have been
reduced.
28.1.2 Structural Repairs
28.1.2.1 Prior to taking up of the structural repairs and
strengthening measures, it is necessary to conduct
detailed damage assessment to determine:
a) the structural condition of the building to
decide whether a structure is amendable for
repair; whether continued occupation is
permitted; to decide the structure as a whole
or a part require demolition, if considered
dangerous;
b) if the structure is considered amendable for
repair then detailed damage assessment of the
individual structural components (mapping of
the crack pattern, distress location; crushed
concrete, reinforcement bending/yielding,
etc). Non-destructive testing techniques could
be employed to determine the residual
strength of the members; and
c) to work out the details of temporary supporting
arrangement of the distressed members so that
they do not undergo further distress due to
gravity loads.
28.1.2.2 After the assessment of the damage of
individual structural elements, appropriate repair
methods are to be carried out componentwise
depending upon the extent of damage. The repair may
consist of the following:
a) Removal of portions of cracked masonry
walls and piers and rebuilding them in richer
mortar. Use of non-shrinking mortar will be
preferable.
b) Addition of reinforcing mesh on both faces
of the cracked wall, holding it to the wall
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
47
through spikes or bolts and then covering it,
suitably, with cement mortar or micro-
concrete.
c) Injecting cement or epoxy like material which
is strong in tension, into he cracks in walls.
d) The cracked reinforced cement elements may
be repaired by epoxy grouting and could be
strengthened by epoxy or polymer mortar
application like shotcreting, jecketting, etc.
28.1.3 Seismic Strengthening
The main purpose of the seismic strengthening is to
upgrade the seismic resistance of a damaged building
while repairing so that it becomes safer under future
earthquake occurrences. This work may involve some
of the following actions:
a) Increasing the lateral strength in one or both
directions by increasing column and wall
areas or the number of walls and columns.
b) Giving unity to the structure, by providing a
proper connection between its resisting
elements, in such a way that inertia forces
generated by the vibration of the building can
be transmitted to the members that have the
ability to resist them. Typical important
aspects are the connections between roofs or
floors and walls, between intersecting walls
and between walls and foundations.
c) Eliminating features that are sources of
weakness or that produce concentration of
stresses in some members. Asymmetrical plan
distribution of resisting members, abrupt
changes of stiffness from one floor to the
other, concentration of large masses and large
openings in walls without a proper peripheral
reinforcement are examples of defects of this
kind.
d) Avoiding the possibility of brittle modes
of failure by proper reinforcement and
connection of resisting members.
28.1.4 Seismic Retrofitting
Many existing buildings do not meet the seismic
strength requirements of present earthquake codes due
to original structural inadequacies and material
degradation due to time or alterations carried out during
use over the years. Their earthquake resistance can be
upgraded to the level of the present day codes by
appropriate seismic retrofitting techniques, such as
mentioned in 28.1.3.
28.1.5 Strengthening or Retrofitting Versus
Reconstruction
28.1.5.1 Replacement of damaged buildings or
existing unsafe buildings by reconstruction is,
generally, avoided due to a number of reasons, the main
ones among them being;
a) higher cost than that of strengthening or
retrofitting,
b) preservation of historical architecture, and
c) maintaining functional social and cultural
environment.
In most instances, however, the relative cost of
retrofitting to reconstruction cost determines the
decision. As a thumb rule, if the cost of repair and
seismic strengthening is less than about 50 percent of
the reconstruction cost, the retrofitting is adopted. This
may also require less working time and much less
dislocation in the living style of the population. On
the other hand reconstruction may offer the possibility
of modernization of the habitat and may be preferred
by well-to-do communities.
28.1.5.2 Cost-wise the building construction including
the seismic code provisions in the first instance, works
out the cheaper in terms of its own safety and that of
the occupants. Retrofitting an existing inadequate
building may involve as much as 4 to 5 times the initial
extra expenditure required on seismic resisting features.
Repair and seismic strengthening of a damaged
building may even be 5 to 10 times as expensive. It is,
therefore, very much safe as well as cost-effective to
construct earthquake resistant buildings at the initial
stage itself according to the relevant seismic IS codes.
28.2 For detailed guidelines for repairs and seismic
strengthening of buildings, reference shall be made to
good practice [7(34)].
28.3 For detailed guidelines for improving earthquake
resistance of low strength masonry buildings, reference
shall be made to good practice [7(35)].
28.4 For detailed guidelines for improving earthquake
resistance of earthen buildings, reference shall be made
to good practice [7(36)].
SECTION 5 SAFETY IN DEMOLITION OF
BUILDINGS
29 GENERAL
29.1 This Section lays down the safety requirements
for carrying out demolition/dismantling work.
29.2 Planning
Before beginning the actual work of demolition a
careful study shall be made of the structure which is to
be pulled down and also of all its surroundings. This
shall, in particular, include study of the manner in
which the various parts of the building to be demolished
are supported and how far the stage by stage demolition
48
NATIONAL BUILDING CODE OF INDIA
will affect the safety of the adjoining structure. A
definite plan of procedure for the demolition work,
depending upon the manner in which the loads of the
various structural parts are supported, shall be prepared
and approved by the engineer-in-charge and this shall
be followed as closely as possible, in actual execution
of the demolition work. Before the commencement of
each stage of demolition, the foreman shall brief the
workmen in detail regarding the safety aspects to be
kept in view.
It should be ensured that the demolition operations do
not, act any stage, endanger the safety of the adjoining
buildings. Moreover, the nuisance effect of the
demolishing work on the use of the adjacent buildings
should be kept to the minimum.
No structure or part of the structure or any floor or
temporary support or scaffold, side wall or any device
for equipment shall be loaded in excess of the safe
carrying capacity, in its then existing condition.
30 PRECAUTIONS PRIOR TO DEMOLITION
30.1 On every demolition job, danger signs shall be
conspicuously posted all around the structure and all
doors and openings giving access to the structure shall
be kept barricaded or manned except during the actual
passage of workmen or equipment. However,
provisions shall be made for at least two independent
exits for escape of workmen during any emergency.
30.2 During nights, red lights shall be placed on or
about all the barricades.
30.3 Where in any work of demolition it is imperative,
because of danger existing, to ensure that no
unauthorized person shall enter the site of demolition
outside hours; a watchman should be employed. In
addition to watching the site he shall also be responsible
for maintaining all notices, lights and barricades.
30.4 All the necessary safety appliances shall be issued
to the workers and their use explained. It shall be
ensured that the workers are using all the safety
appliances while at work.
30.5 The power on all electrical service lines shall be
shut off and all such lines cut or disconnected at or
outside the property line, before the demolition work
is started. Prior to cutting of such lines, the necessary
approval shall be obtained from the electrical
authorities concerned. The only exception will be any
power lines required for demolition work itself.
30.6 All gas, water steam and other service lines shall be
shut off and capped or otherwise controlled at or outside
the building line, before demolition work is started.
30.7 All the mains and meters of the building shall be
removed or protected from damage.
30.8 If a structure to be demolished has been partially
wrecked by fire, explosion or other catastrophe, the
walls and damaged roofs shall be shored or braced
suitably.
30.9 Protection of the Public
30.9.1 Safety distances to ensure safety of the public
shall be clearly marked and prominently sign posted.
Every sidewalk or road adjacent to the work shall be
closed or protected. All main roads, which are open to
the shall be kept open to the public clear and
unobstructed at all times. Diversions for pedestrians
shall be constructed, where necessary for safety.
30.9.2 If the structure to be demolished is more than
two storeyed or 7.5 m high, measured from the side
walk or street which can not be closed or safely
diverted, and the horizontal distance from the inside
of the sidewalk to the structure is 4.5 m or less, a
substantial sidewalk shed shall be constructed over the
entire length of the sidewalk adjacent to the structure,
of sufficient width with a view to accommodating the
pedestrian traffic without causing congestion. The side
walk shed shall be lighted sufficiently to ensure safety
at all times. For detailed information reference may be
made to good practice [7(37)].
A toe board of at least 1 m high above the roof of the
shed shall be provided on the outside edge and ends of
the sidewalk shed. Such boards may be vertical or
inclined outward at not more than 45°.
Except where the roof of a sidewalk shed solidly abuts
the structure, the face of the sidewalk shed towards
the building shall be completely closed by providing
sheating/planking to prevent falling material from
penetrating into the shed.
The roof of sidewalk sheds shall be capable of sustaining
a load of 73 N/mm 2 . Only in exceptional cases, say due
to lack of other space, the storing of material on a
sidewalk shed may be permitted in which case the shed
shall be designed for a load of 146 N/mm 2 . Roof of
sidewalk shed shall be designed taking into account the
impact of the falling debris. By frequent removal of loads
it shall be ensured that theumaximum load, at any time,
on the roof of work shed is not more than 6 000 N/mm 2 .
The height of sidewalk shed shall be such as to give a
minimum clearance of 2.4 m.
Sidewalk shed opening, for loading purposes, shall be
kept closed at all time except during actual loading
operations.
The deck flooring of the sidewalk shed shall consist
of plank of not less than 50 mm in thickness closely
laid and deck made watertight. All members of the shed
shall be adequately bracked and connected to resist
displacement of members or distortion of framework.
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
49
30.9.3 When the horizontal distance from the inside
of the sidewalk to the structure is more than 4.5 m
and less than 7.5 m, a sidewalk shed or fence a
substantial railing shall be constructed on the inside
of the sidewalk or roadway along the entire length of
the demolition side of the property with movable bars
as may be necessary for the proper prosecution of
the work.
31 PRECAUTIONS DURING DEMOLITION
31.1 Prior to commencement of work, all material of
fragile nature like glass shall be removed.
31.2 All openings shall be boarded up.
31.3 Dust shall be controlled by suitable means to
prevent harm to workmen.
31.4 Stacking of materials or debris shall be within
safe limits of the structural member. Additional
supports, where necessary, shall be given.
31.5 Adequate natural or artificial lighting and
ventilation shall be provided for the workmen.
32 SEQUENCE OF DEMOLITION OPERATIONS
32.1 The demolition work shall be proceeded with in
such a way that:
a) it causes the least damage and nuisance to the
adjoining building and the members of the
public, and
b) it satisfies all safety requirements to avoid any
accidents.
32.2 All existing fixtures required during demolition
operations shall be well protected with substantial
covering to the entire satisfaction of the rules and
regulations of the undertakings or they shall be
temporarily relocated.
32.3 Before demolition work is started, glazed sash,
glazed doors and windows, etc, shall be removed. All
fragile and loose fixtures shall be removed. The lath
and all loose plaster shall be stripped off throughout
the entire building. This is advantageous because it
reduces glass breakage and also eliminates a large
amount of dust producing material before more
substantial parts of the buildings are removed.
32.4 All well openings which extend down to floor
level shall be barricaded to a height of not less than
1 m above the floor level. This provision shall not apply
to the ground level floor.
32.5 All floor openings and shafts not used for material
chutes shall be floored over and be enclosed with guard
rails and toe boards.
systematically storey by storey. In the descending
order. All work in the upper floor shall be completed
and approved by the engineer-in-charge prior to
disturbance to any supporting member on the lower
floor. Demolition of the structure in sections may be
permitted in exceptional cases if proper precautions
are ensured to prevent injuries to persons and damage
to property.
33 WALLS
33.1 While walls of sections of masonry are being
demolished, it shall be ensured that they are not allowed
to fall as single mass upon the floors of the building
that are being demolished so as to exceed the safe
carrying capacity of the floors. Overloading of floors
shall be prevented by removing the accumulating
debris through chutes or by other means immediately.
The floor shall be inspected by the engineer-in-charge
before undertaking demolition work and if the same is
found to be incapable to carry the load of the debris,
necessary additional precautions shall be taken so as
to prevent any possible unexpected collapse of the
floor.
33.2 Walls shall be removed part by part. Stages shall
be provided for the men to work on if the walls are
less than one and a half brick thick and dangerous to
work by standing over them.
33.3 Adequate lateral bracing shall be provided for
walls which are unsound. For detailed information
reference may be made to good practice [7(37)].
34 FLOORING
34.1 Prior to removal of masonry or concrete floor
adequate support centering shall be provided.
34.2 When floors are being removed, no workmen
shall be allowed to work in the area, directly underneath
and such area shall be barricaded to prevent access to
it.
34.3 Planks of sufficient strength shall be provided to
give workmen firm support to guard against any
unexpected floor collapse.
34.4 When floors are being removed no person shall
be allowed to work in an area directly underneath and
access to such area shall be barricaded.
35 DEMOLITION OF STEEL STRUCTURES
35.1 When a derrick is used, care shall be taken to see
that the floor on which it is supported is amply strong
for the loading so imposed. If necessary heavy planking
shall be used to distribute the load to floor beam and
girders.
32.6 The demolition shall always proceed 35.2 Overloading of equipment shall not be allowed.
50
NATIONAL BUILDING CODE OF INDIA
35.3 Tag lines shall be used on all materials being
lowered or hoisted up and a standard signal system
shall be used and the workmen instructed on the
signals.
35.4 No person shall be permitted to ride the load line.
35.5 No beams shall be cut until precautions have been
taken to prevent it from swinging freely and possibly
striking any worker or equipment to any part of the
structure being demolished.
35.6 All structural steel members shall be lowered
from the building and shall not be allowed to drop.
36 CATCH PLATFORM
36.1 In demolition of exterior walls of multistorey
structures, catch platform of sufficient strength to
prevent injuries to workers below and public shall be
provided, when the external walls are more than 20 m
in height.
36.2 Such catch platform shall be constructed and
maintained not more than 3 storeys below the storey
from which exterior wall is being demolished.
When demolition has progressed to within 3 storeys
of ground level, catch platform will not be considered
necessary.
36.3 Catch platform shall be capable of sustaining a
live load of not less than 6 100 N/m 2 .
36.4 Materials shall not be dumped on the catch
platform nor shall they be used for storage of materials.
37 STAIRS, PASSAGEWAYS AND LADDERS
37.1 Stairs with railings, passageways and ladders
shall be left in place as long as possible and maintained
in a safe condition.
37.2 All ladders shall be secured against, slipping out
at the bottom and against movement in any direction
at the top.
38 MECHANICAL DEMOLITION
When demolition is to be performed by mechanical
devices, such as weight ball and power shovels, the
following additional precautions may be observed:
a) The area shall be barricaded for a minimum
distance of Vh times the height of the wall,
b) While the mechanical device is in operation,
no workmen shall be allowed to enter the
building being demolished,
c) The device shall be so located as to avoid
falling debris, and
d) The mechanical device when being used shall
not cause any damage to adjacent structure,
power line, etc.
39 DEMOLITION OF CERTAIN SPECIAL
TYPES AND ELEMENTS OF STRUCTURES
39.1 Roof Trusses
If a building has a pitched roof, the structure should
be removed to wall plate level by hand methods.
Sufficient purlins and bracing should be retained to
ensure stability of the remaining roof trusses while each
individual truss is removed progressively.
39.1.1 Temporary bracking should be added, where
necessary, to maintain stability. The end frame opposite
to the end where dismantling is commenced, or
a convenient intermediate frame should be
independently and securely guyed in both directions
before work starts.
39.1.2 On no account should the bottom tie of roof
trusses be cut until the principal rafters are prevented
from making out ward movement.
39.1.3 Adequate hoisting gears suitable for the loads
shall be provided. If during demolition any thing is to
be put on the floor below the level of the truss, it shall
be ensured that the floor is capable of taking the load.
39.2 Heavy Floor Beams
Heavy baulks of timber and steel beams should be
supported before cutting at the extremities and should
then be lowered gently to a safe working place.
39.3 Jack Arches
Where tie rods are present between main supporting
beams, these should not be cut until after the arch or
series of arches in the floor have been removed. The
floor should be demolished in strips parallel to the span
of the arch rings (at right angles to the main floor
beams).
39.4 Brick Arches
Expert advice should be obtained and, at all stages of
the demolition, the closet supervision should be given
by persons fully experienced and conversant in the type
of work to ensure that the structure is stable at all times.
However, the following points may be kept in view.
39.4.1 On no account should the restraining influence
of the abutments be removed before the dead load of
the spandrel fill and the arch rings are removed.
39.4.2 A single span arch can be demolished by hand
by cutting narrow segments progressively from each
springing parallel to the span of the arch, until the width
of the arch has been reduced to a minimum which can
then be collapsed.
39.4.3 Where deliberate collapse is feasible, the crown
may be broken by the demolition ball method working
progressively from edges to the centre.
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
51
39.4.4 Collapse of the structure can be effected in one
action by the use of explosives. Charges should be
inserted into bore holes drilled in both arch and
abutments.
39.4.5 In multi-span arches, before individual arches
are removed, lateral restraint should be provided at the
springing level. Demolition may then proceed as for
single span; where explosives are used it is preferable
to ensure the collapse of the whole structure in one
operation to obviate the chance of leaving unstable
portion standing.
39.5 Cantilever (Not Part of a Framed Structure)
Canopies, cornices, staircases and balconies should be
demolished or supported before tailing down load is
removed.
39.6 In-situ Reinforced Concrete
Before commencing demolition, the nature and
condition of the concrete, the condition and position
of reinforcement, and the possibility of lack of
continuity of reinforcement should be ascertained.
Demolition should be commenced by removing
partitions and external non-load bearing cladding.
39.6.1 Reinforced Concrete Beams
A supporting rope should be attached to the beam.
Then the concrete should be removed from both ends
by pneumatic drill and the reinforcement exposed.
The reinforcement should then be cut in such a way
as to allow the beam to be lowered under control to
the floor.
39.6.2 Reinforced Concrete Columns
The reinforcement should be exposed at the base after
restraining wire guy ropes have been placed round the
member at the top. The reinforcement should then be
out in such a way as to allow it to be pulled down to
the floor under control.
39.6.3 Reinforced Concrete Walls
These should be cut into strips and demolished as for
columns.
39.6.4 Suspended Floors and Roofs
The slab should be cut into strips parallel to the main
reinforcement and demolished strip by strip. Where
ribbed construction has been used, the principle of
design and method of construction should be
determined before demolition is commenced. Care
should be taken not to cut the ribs inadvertently.
39.7 Precast Reinforced Concrete
Due precautions shall be taken to avoid toppling over
of prefabricated units or any other part of the structure
and whenever necessary temporary supports shall be
provided.
39.8 Prestressed Reinforced Concrete
Before commencing of the demolition work, advice
of an engineering expert in such demolition shall be
obtained and followed.
40 LOWERING, REMOVAL AND DISPOSAL
OF MATERIALS
40.1 Dismantled materials may be thrown to the
ground only after taking adequate precautions. The
material shall preferably be dumped inside the building.
Normally such materials shall be lowered to the ground
or to the top of the sidewalk shed where provided by
means of ropes or suitable tackles.
40.2 Through Chutes
40.2.1 Wooden or metal chutes may be provided from
removal of materials. The chutes shall preferably be
provided at the centre of the building for efficient
disposal of debris.
40.2.2 Chutes, if provided at an angle of more than
45° from the horizontal, shall be entirely enclosed on
all the four sides, except for opening at or about the
floor level for receiving the materials.
40.2.3 To prevent the descending material attaining a
dangerous speed, chute shall not extend in an unbroken
line for more than two storeys. A gate or stop shall be
provided with suitable means for closing at the bottom
of each chute to stop the flow of materials.
40.2.4 Any opening into which workmen dump debris
at the top of chute shall be guarded by a substantial
guard rail extending at least 1 m above the level of the
floor or other surface on which men stand to dump the
materials into the chute.
40.2.5 A toe board or bumper, not less than 50 mm
thick and 150 mm high shall be provided at each chute
openings, if the material is dumped from the wheel
barrows. Any space between the chute and the edge of
the opening in the floor through which it passes shall
be solidly planked over.
40.3 Through Holes in the Floors
40.3.1 Debris may also be dropped through holes in
the floor without the use of chutes. In such a case the
total area of the hole cut in any intermediate floor, one
which lies between floor that is being demolished and
the storage floor shall not exceed 25 percent of such
floor area. It shall be ensured that the storage floor is
of adequate strength to withstand the impact of the
falling material.
40.3.2 All intermediate floor openings for passage of
52
NATIONAL BUILDING CODE OF INDIA
materials shall be completely enclosed with barricades
or guard rails not less than 1 m high and at a distance
of not less than 1 m from the edge of general opening.
No barricades or guard rails shall be removed until
the storey immediately above has been demolished
down to the floor line and all debris cleared from the
floor.
40.3.3 When the cutting of a hole in an intermediate
floor between the storage floor and the floor which is
being demolished makes the intermediate floor or any
portion of it unsafe, then such intermediate floor shall
be properly shored. It shall also be ensured that the
supporting walls are not kept without adequate lateral
restraints.
40.4 Removal of Materials
40.4.1 As demolition work proceeds, the released
serviceable materials of different types shall be
separated from the unserviceable lot (hereinafter called
'MALBA') at suitable time intervals and properly
stocked clear of the spots where demolition work is
being done.
40.4.2 The MALBA obtained during demolition shall
be collected in well-formed heaps at properly selected
places, keeping in view safe conditions for workmen
in the area. The height of each MALBA heap shall be
limited to ensure its toppling over or otherwise
endangering the safety of workmen or passersby.
40.4.3 The MALBA shall be removed from the
demolition site to a location as required by the local
civil authority. Depending on the space available at the
demolition site, this operation of conveying MALBA to
its final disposal location may have to be carried out a
number of times during the demolition work. In any
case, the demolition work shall not be considered as
completed and the area declared fit for further occupation
till all the MALBA has been carried to its final disposal
location and the demolition areas tidied up.
40.4.4 Materials which are likely to cause dust
nuisance or undue environmental pollution in any other
way, shall be removed from the site at the earliest and
till then they shall be suitable covered. Such materials
shall be covered during transportation also.
40.4.5 a) Glass and steel should be dumped or
buried separately to prevent injury.
b) Workman should be provided with
suitable protective gears for personal
safety during works, lie safety helmets,
boots, hand gloves, goggles, special
attire, etc.
c) The work of removal of debris should be
carried out during day. In case of poor
visibility artificial light may be provided.
d) The debris should first be removed from
top. Early removal from bottom or sides
of dump may cause collapse of debris,
causing injuries.
41 MISCELLANEOUS
41.1 No demolition work should be carried out during
night as far as possible, especially when the structure
to be demolished is in an inhabited area. If such night
work has to be done, additional precautions by way of
additional red warning signals, working lights and
watchmen, shall be provided to avoid any injury to
workmen and public. Demolition work shall not be
carried out during storm and heavy rain.
41.2 Warning devices shall be installed in the area to
warn the workers in case of any danger.
41.3 Safety devices like industrial safety helmets
conforming to the accepted standards [7(9)] and
goggles made of celluloid lens, shall be issued to the
workmen. Foreman-in-charge of the work areas shall
ensure that all the workmen are wearing the safety
devices before commencing any work.
41.4 Construction sheds and tool boxes shall be so
located as to protect workers from injuries from the
falling debris.
41.5 Where there is a likelihood of injuries to hands
of workmen when demolishing RCC, steel structures,
etc, gloves of suitable materials shall be worn by
workmen.
41.6 Sufficient protection by way of both overhead
cover and screens shall be provided to prevent injuries
to the workmen and the public.
41.7 Safety belts or ropes shall be used by workmen
when working at higher levels.
41.8 Grading of Plot
When a building has been demolished and no building
operation has been projected or approved, the vacant
plot shall be filled, graded and maintained in
conformity to the established street grades at curb level.
The plot shall be maintained free from the
accumulation of rubbish and all other unsafe and
hazardous conditions which endangers the life or health
of the public; and provisions shall be made to
prevent the accumulation of water or damage to any
foundations on the premises or the adjoining property.
42 FIRST-AID
42.1 A copy of all pertinent regulations and notices
concerning accidents, injury and first-aid shall be
prominently exhibited at the work site.
42.2 Depending on the scope and nature of the work,
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
53
a person, qualified in first-aid shall be available at work
site to render and direct first-aid to casualties. He shall
maintain a list of individuals qualified to serve in first-
aid work. Enough first-aid kit, including a stretcher
and cot with accessories shall be provided at site. A
telephone may be provided to first-aid assistant with
telephone numbers of the hospitals prominently
displayed.
Complete reports of all accidents and action taken
thereon shall be forwarded to the competent authorities.
ANNEX A
(Clause 2.L2)
PROGRAMME EVALUATION AND REVIEW TECHNIQUE, AND
CRITICAL PATH METHOD
A-0 INTRODUCTION
A-0.1 Programme Evaluation and Review Technique
(PERT) and Critical Path Method (CPM) are modern
management tools or devices, which have made it
possible to achieve considerable savings in cost and
time of construction. They can be used with advantage
for demolition, constructional safety and fire protection
measures, by including them in the list of activities
(also called events) along-side with other 'events' of
the project.
A-0.2 Advance Planning
A-0.2.1 PERT and CPM enable us to achieve judicious
employment and utilization of resources, such as
labour, materials, and equipment by pre-determining
the various stages, listing out the various activities and
drawing out 'Arrow Network Diagram'.
A-0.3 Synchronization of Sub-Projects
A-0.3.1 Another extremely important advantage of
CPM is that various factors influencing completion of
a project can be scientifically planned to be coordinated
such that the completion of various sub-projects and
services, such as furniture, sewage, electricity and
water supply synchronises.
A-l PREPARATION OF CPM CHART (LISTING
OUT THE ACTIVITIES)
A-l.l The most important step in preparation of CPM
network is to list out the activities involved to the
minutest details. For example, a few activities in case
of a building project are given below:
a)
b)
c)
d)
Planning and designing of building by
architect, engineer and approval of plans by
the Authority.
Making the land available.
Outlining detailed specifications.
Procurement of materials, such as sand,
cement, stone and timber; and plants, such as
concrete mixer, vibrators, water pump for
curing.
e) Soil explorations and trial pits.
f) Excavation in foundations, including
demolition, if needed.
g) 1} Construction safety aspects specially in case
of pile foundations.
h) 1} Blasting if required (for deep foundations).
j) 1} Fire protection measures.
A-1.2 Time Needed for Each Activity
An assessment is to be made to find out the time needed
for each activity and then to list out those activities,
which can be executed concurrently (or simultaneously)
with each other. For example, while designing of the
building is in hand, correspondence for land purchase
can also go on side by side; or while work in
foundations is in progress, order for 'joinery' can be
placed.
A-1.3 Critical Activity
It should then be seen as to which of the activities are
critical, that is which items are such that a single day's
delay will mean overall delay on the project. Contrary
to this, it will be seen from CPM Network that certain
activities can be delayed to a certain extent without
delaying the completion of the project. This is a very
useful and valuable information for the 'Project
Manager' .That is where resources scheduling becomes
easier and economical and a time saver. It eliminates
chances of idle labour and higher expenses which are
results of haphazard planning.
A-2 UPDATING
A-2.1 In implementing the CPM, there could be gaps
between the planned CPM and actual progress
1} These can be further sub-divided and number of activities
increased.
54
NATIONAL BUILDING CODE OF INDIA
or position on ground. This should be checked
periodically-weekly, fortnightly or monthly depending
on nature and size of project.
A-3 GENERAL
A-3.1 In case of projects being executed by contractors
for the owners, or departments, it is recommended that
it should be an essential condition of the contract to
submit a CPM Chart along with the quoted tenders.
This will ensure that the construction work will be
according to a systematic, engineer-like and well-knit
plan of execution.
SI
No.
ANNEX B
{Clause A A)
CHECK LIST FOR STACKING AND STORAGE OF MATERIALS
Material/Component
Base
Stack
Type of Cover
Firm Hard Off- Heaps Tiers Flat Vertical Open Open Under
Level Fi oor Floor but shed
Ground covered
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
1.
Cement
^
•
•
2.
Lime
a) Quicklime
b) Hydrated lime
^
•
•
•
•
•
3.
Stones and Aggregates
a) Stones, aggregates, fly
and cinder
b) Veneering stones
ash
^
•
^
•
•
•
•
4.
Bricks and Blocks
•
•
•
5.
Tiles
a) Clay and concrete floor, S
wall and roof tiles
b) Ceramic tiles ^
6. Partially Pre-fabricated Wall
and Roof Components
a) RC planks, prefabricated ^
brick panels and ferro-
cement panels
b) Channel units, cored units ^
and L-Panels
c) Waffle units, RC joists, S
single tee and double tee
7. Timber
8. Steel •
9. Aluminium Sections S
10. Doors, Windows and ^
Ventilators
11. Roofing Sheets
a) AC •
b) GI and Aluminium sheets S
c) Plastic sheets
• ^
• ^
•
•
^
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PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
55
ANNEX B — Continued
(1)
(2)
(3) (4) (5) (6) (7) (8) (9) (10) (11) (12)
12.
Boards like Plywood,
Particle Boards, Fibre
Boards, Blockboards and
Gypsum Board
13.
Plastic and Rubber Flooring
a) Sheets in rolls
•
b) Tiles
y
14.
Glass Sheets
s
15.
Glass Bricks/Blocks
s
16.
CI, GI and AC Pipes and
Fittings
a) Pipes
s
b) CI and GI Fittings
s
c) AC Fittings
s
17.
Polyethylene Pipes
18.
Unplasticized PVC Pipes
s
19.
Bitumen, Road Tar,
Asphalt, etc in Drums
s
20.
Oil Paints
s
21.
Sanitary Appliances
s
s
s
V V
s s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
ANNEX C
(Clause 26.3.2.2.2)
COMMON CAUSES FOR MAINTENANCE PROBLEMS
C-0 MAJOR CAUSES FOR MAINTENANCE
PROBLEMS
C-l FLOORS
a) Poor quality of construction which includes
quality of construction material and
workmanship.
b) Improper slopes, mainly in kitchen, bathrooms/
toilets etc.
c) Lack of rounding at junctions of walls with
floors.
d) Lack of dampproof course treatment in walls
and particularly in sunken floors.
e) Poor design of building.
C-2 ROOFS
a) Inadequate roof slopes.
b) Inferior quality of construction.
c) Cracks on roof surfaces.
d) Inadequate provision of rain water spouts.
e) Blockages in gratings/rain water pipes.
f) Worn out felts.
g) Bubbling up of tarfelt and separation of
joints.
h) Leakage from the openings provided on the
roof.
C-3 PLUMBING
a) Inadequate slopes in soil/waste pipes.
b) Improper lead joints.
c) Joints in walls. ,
d) Improper junctions of stacks.
e) Inadequate cleaning eyes at junctions.
f) Inadequate slopes in sewage pipes.
g) Throwing of solid wastes in WC's.
h) Lack of periodical checking and cleaning.
j) Lack of motivation/education to users for
proper use.
k) Overflow from service tanks,
m) Inferior quality of fittings and fixtures,
n) Inadequate design.
56
NATIONAL BUILDING CODE OF INDIA
C-4 DRAINAGE
a) Improper surface dressing around buildings
and improper upkeep of surroundings.
b) Growth of wild grass and vegetation.
c) Inadequate drainage system around the
building.
d) Inadequate slope of the drains or drainage
pipes.
e) Inadequate number of inspection chambers.
f) Theft of manhole covers etc.
g) Throwing of solid waste in the open surface
drains.
C-5 ELECTRICAL
a) Loose connections.
b) Improper earthing and earth connections.
c) Damages to wires, cables and other
installations.
d) Under rated cables/wires and other
installations.
ANNEX D
(Clause 26.6.5)
FORMAT FOR INSPECTION REPORT
Date:
Building/Block:
Condition
Sound
Suspect
Defective
FLOORS & STAIRCASES
Ground Floor
Finish
Skirting
Structure
Damp-proofing
Ceiling
Under floors, spaces, (Suspended floors)
Termites/insects
Upper Floors
Finish
Structure
Ceiling
Suspended ceiling
Stair cases
Structure
Treads
Finishes
Balustrade
Soffits
Finish
ROOFING
Flat/Pitched
Finish
Insulation
Structure
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
57
ANNEX D — Continued
Roof lights/glazing
Parapets
Cutters
Rain Water Pipes
Mud Phuska
Roof interiors (Pitched)
Growth of vegetation
SANITARY INSTALLATIONS
Plumbing
Fittings/Pipings, WCs
Taps
Sinks
Basins
Urinals
Cisterns
Geysers
Sewage Disposal
Soil pipes
Manholes
Sewerlines
Drainage
Gully chambers
Sewers
Surface drains
Inspection chambers
Structural movement
Failure of material
Design or construction defects
Overhead Tanks/Underground
Sumps/Terrace Tanks
Septic Tanks
Remarks
Condition
Sound
Suspect
Defective
ANNEX E
(Clause 26 .7 ".3.2)
GUIDELINES FOR MAINTENANCE OF ELECTRICAL EQUIPMENTS
E-l In case of electrical appliances, manufacturer's
instructions for the usage and maintenance of the
equipment should be strictly followed.
E-2 The detailed/working drawings of all the
components of electrical installations should always
be available with the maintenance unit. Following
records should be available.
a) Manufacturer's name
b) Nameplate of the equipment and its sailent
features such as capacity, rating etc.
58
NATIONAL BUILDING CODE OF INDIA
c) Manufacturer's recommendations regarding
availability/usage of spare parts.
d) Manufacturer' s recommendations for
periodical maintenance and post fault
maintenance.
e) Details of the maintenance operations
performed in the past.
E-3 Care should be taken while selecting replacement
parts. The spare parts should be correct and suitable,
preferably as recommended by the manufacturer of the
installation. During the placement of order for the
supply of spare parts, nameplate particulars and serial
number should be quoted.
E-4 The space where the equipment is kept should be
clean and properly ventilated. Equipment should not
be disturbed needlessly. Before cleaning, the
equipment should be made dead. For internal cleaning
a section cleaner should be used.
E-5 Covers and doors should not be left open
unnecessarily during maintenance. Afterwards they
should be promptly and correctly closed and locked.
E-6 Before removing the covers and connections, all
covers and cable terminations should be marked to
ensure correct replacements. Disturbed connections
and temporary connections should be marked to
facilitate re-connection. Temporary connections and
markings should be removed before the installation is
put to use.
E-7 Those connections which have not been disturbed
should also be checked for soundness and overheating.
E-8 All insulations should be regularly checked. Solid
insulations should be checked for cracks and other
defects. Fibrous and organic insulations should be
checked for sign of blistering, delamination and
mechanical damage. For insulating oils the interval
between tests should be carried out as per the
recommendations of the manufacturer and keeping the
adverse environmental conditions in mind.
E-9 It should be ensured that the earthing connections
are sound and all contact screws are tight.
E-10 During the examination of interlocks it is
necessary to take precautions to prevent danger to plant
or persons in the event of malfunction or inadvertent
operation. A person responsible for checking and
maintaining any interlock system should have thorough
knowledge of the extent, nature and function of the
interlock.
E-ll If the equipment is ventilated then it should be
ensured that the airflow is smooth and not restricted.
If filters are provided, they should be cleaned or
replaced as necessary.
E-12 The standby system for tripping and closing
supplies should always be kept in good order.
Indicators and alarms should be maintained in time
with the manufacturer's instructions.
E-13 Tools, spares and instruments should be stored
near to the installation. These should be regularly
checked against an inventory.
E-14 Before the start of maintenance of the circuit
switches it should be ensured that all incoming and
outgoing main auxiliary circuits are dead and remain
so during the maintenance. Over heating of the circuit
switches is the root cause for faults. Overheating may
be caused by inadequate ventilation, overloading,
loose connection, insufficient contact force and
malalignment.
E-15 Some circuit breakers are not intended to be
maintained, such as miniature circuit breakers (MCBs).
Such items should not be dismantled for maintenance.
These should be renewed periodically.
E-16 For the maintenance of fuses periodical
inspection should be done for correct rating, security,
overheating and correct location/orientation. Element
of renewable fuses should be renewed when the
deterioration is apparent. The availability and correct
replacement of fuse links should be ensured.
E-17 If a fuse link of certain rating has failed and is
replaced, then all fuse-links of same rating apparently
subjected to the fault should be destroyed and replaced
by new fuse links.
E-18 In order to be reasonably sure that circuit breaker
is capable of operation when required, these should be
tripped and reclosed at regular intervals. Tripping
should be proved manually and where possible
electrically via the protective relay contacts. The
leakage of oil, sign of corrosion, and any unusual smell
which may indicate over-heating should be detected
through inspections.
E-19 Timing devices are mostly designed for specialist
maintenance. These should not be dismantled for
maintenance or overhaul purposes unless specifically
recommended by the manpfacturers'. Actual timing
periods should be verified with set values and
application requirements.
E-20 In case of cable boxes and terminations, security
of mounting and earthing should be examined. Exposed
tails should be inspected for good conditions of
insulation and freedom from moisture.
E-21 Battery cells should be inspected for shedding
of active material, sedimentation and buckling of
plates. Level of electrolyte should be regularly checked
and the level should be corrected with distilled water.
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
59
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and * accepted standards'
in the fulfillment of the requirements of the Code. The
latest version of a standard shall be adopted at the time
of enforcement of the Code. The standards listed may
be used by the Authority as a guide in conformance
with the requirements of the referred clauses in the
Code.
(1)
IS No.
a) Foundations
1080 : 1985
Title
1904 : 1986
2911
Code of practice for design
and construction of shallow
foundations on soils (other
than raft, ring and shell)
(second revision)
Code of practice for design
and construction of
foundations in soils:
General requirements
(third revision)
Code of practice for design
and construction of pile
foundations
(Part 1/Sec 1) : 1979 Concrete piles, Section 1
Driven cast in-situ concrete
piles (first revision)
(Part 1/Sec 2) : 1979 Concrete piles, Section 2
Board cast in-situ piles
(first revision)
(Part 1/Sec 3) : 1979 Concrete piles, Section 3
Driven precast concrete
piles (first revision)
(Part 1/Sec 4) ; 1984 Concrete piles, Section 4
Bored precast concrete
piles (first revision)
Timber piles (first revision)
Under-reamed piles (first
revision)
Load test on piles (first
revision)
Code of practice for design
and construction of machine
foundations
Foundations for recipro-
cating type machines
(second revision)
Foundations for impact
type machines (hammer
foundations) (first revision)
(Part 2) : 1980
(Part 3) : 1980
(Part 4): 1985
2974
(Part 1) : 1982
(Part 2): 1980
IS No.
(Part 3) : 1992
(Part 4) : 1979
(Part 5) : 1987
9456 : 1980
9556 : 1980
13094 : 1992
15284
(Part 1) : 2003
b) Masonry
1597
(Part 1) : 1992
(Part 2): 1992
2110: 1980
2212 : 1991
2250 : 1981
2572 : 1963
Title
Foundations for rotary type
machines (medium and
high frequency) (second
revision)
Foundations for rotary type
machines of low frequency
(first revision)
Foundations for impact
machines other than
hammers forging and
stamping press pig breakers
(drop crusher and jolter)
(first revision)
Code of practice for design
and construction of conical
and hyperbolic paraboidal
types of shell foundations
Code of practice for design
and construction of
diaphragm walls
Guidelines for selection of
ground improvement
techniques for foundation
in weak soils
Design and construction
for ground improvement:
Part 1 Stone columns
Code of practice for
construction of stone
masonry
Rubble stone masonry (first
revision)
Ashlar masonry (first
revision)
Code of practice for in-situ
construction of walls in
/buildings with soil-cement
(first revision)
Code of practice for
brickwork (first revision)
Code of practice for
preparation and use of
masonry mortars (first
revision)
Code of practice for
construction of hollow
concrete block masonry
60
NATIONAL BUILDING CODE OF INDIA
IS No.
3630 : 1992
4407 : 1967
4441 : 1980
4442 : 1980
4443 : 1980
6041 : 1985
6042 : 1969
Title
Code of practice for
construction of non-load
bearing gypsum block
partitions {first revision)
Code of practice for reed
walling
Code of practice for use of
silicate type chemical
resistant mortars (first
revision)
Code of practice for use of
sulphur type chemical
resistant mortars (first
revision)
Code of practice for use of
resin type chemical
resistant mortars (first
revision)
Code of practice for
construction of autoclaved
cellular concrete block
masonry (first revision)
Code of practice for
construction of light weight
concrete block masonry
(first revision)
c) Timber and Bamboo
1634: 1992
2366 : 1983
3670 : 1989
4913 ; 1968
4983 : 1984
5390 : 1984
11096: 1984
Code of practice for design
and constructions of wood
stair for houses (second
revision)
Code of practice for nail-
jointed timber construction
(first revision)
Code of practice for
construction of timber
floors (first revision)
Code of practice for
selection, installation and
maintenance of timber
doors and windows
Code of practice for design
and construction of nail
laminated timber beams
Code of practice for
construction of timber
ceilings (first revision)
Code of practice for design
and construction of bolt-
jointed timber construction
IS No.
12506 : 1988
d) Concrete
456 : 2000
457 : 1957
2502 : 1963
2541 : 1991
3370
(Part 1) : 1965
(Part 2) : 1965
(Part 3) : 1967
3558 : 1983
5817 : 1992
7246 : 1974
7861
(Part 1) : 1975
(Part 2) : 1981
10262 : 1982
10359 : 1982
Title
Code of practice for
improved thatching of roof
with wrought and fire
retardant treatment
Code of practice for plain
and reinforced concrete
(fourth revision)
Code of practice for general
construction of plain and
reinforced concrete for
dams and other massive
structures
Code of practice for
bending and fixing of bars
for concrete reinforcement
Code of practice for
preparation and use of lime
concrete, (second revision)
Code of practice for
concrete structures for the
storage of liquids
General requirements
Reinforced concrete
structures
Prestressed concrete
structures
Code of practice for use of
immersion vibrators for
consolidating concrete
(first revision)
Code of practice for
preparation and use of lime
pozzolana mixture concrete
in buildings and roads (first
revision)
Recommendations for use
of table vibrators for
consolidating concrete
Qode of practice for
extreme whether concreting
Recommended practice for
hot weather concreting
Recommended practice for
cold weather concreting
Recommended guidelines
for concrete mix design
Code of practice for
manufacture and use of
lime pozzolana concrete
blocks for paving
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
61
IS No.
14687 : 1999
e) Steel
800 : 1984
801 : 1975
Title
Guidelines for falsework
for concrete structures
Code of practice for general
steel construction (second
revision)
Code of practice for use of
cold formed light gauge
steel structural members
in general building
construction {first revision)
Code of practice for use
of steel in gravity water
tanks
Code of practice for use
of steel tubes in general
building construction (first
revision)
Code of practice for high
strength bolts in steel
structures (first revision)
Code of practice for
corrosion protection of
light gauge steel sections
used in building
Code of practice for design
and construction of steel
chimneys
Mechanical aspects (first
revision)
Structural aspects (first
revision)
w^ Code of practice for
(Parts 1 to 3) : 1977 protection of iron and steel
structures from atmospheric
corrosion
9077 : 1979 Code of practice of
corrosion protection of
steel reinforcement in RB
and RCC construction
9172 : 1979 Recommended design
practice for corrosion
prevention of steel structures
805 : 1968
806 : 1968
4000 : 1992
4180:1967
6533
(Part 1) : 1989
(Part 2) : 1989
8629
f) Flooring and Roofing
658 : 1982
1196: 1978
Code of practice for
magnesium oxychloride
composition floors (second
revision)
Code of practice for laying
bitumen mastic flooring
(second revision)
IS No.
1197: 1970
1198: 1982
1443 : 1972
2118: 1980
2119: 1980
2204 : 1962
2571 : 1970
2700 : 1987
2792 : 1964
2858 : 1984
3007
(Part 1) : 1999
(Part 2) : 1999
3670 : 1989
5119
(Part 1) : 1968
5318: 1969
Title
Code of practice for laying
of rubber floors (first
revision)
Code of practice for laying,
fixing and maintenance of
linoleum floor (first
revision)
Code of practice for laying
and finishing of cement
concrete flooring tiles (first
revision)
Code of practice for
construction of jack-arch
type of building floor or
roof (first revision)
Code of practice for
construction of brick-cwm-
concrete composite (Madras
terrace) floor or roof (first
revision)
Code of practice for
construction of reinforced
concrete shell roof
Code of practice for laying
in-situ cement concrete
flooring (first revision)
Code of practice for
roofing with wooden
shingles (first revision)
Code of practice for design
and construction of stone
slab over joist floor
Code of practice for
roofing with Mangalore
tiles (first revision)
Code of practice for laying
of asbestos cement sheets:
Corrugated sheets (first
f revision)
Semi-corrugated sheets
(first revision)
Code of practice for
construction of timber
floors (first revision)
Code of practice for laying
and fixing of sloped roof
coverings: Part 1 Slating
Code of practice for laying
of flexible PVC sheet and
tile flooring
62
NATIONAL BUILDING CODE OF INDIA
IS No.
Title
IS No.
5389 : 1969
Code of practice for laying
(Part 1) : 1971
of hard wood parquet and
(Part 2): 1971
wood block floors
IS 1609 : 1991
5390 : 1984
Code of practice for
construction of timber
ceilings (first revision)
5766 : 1970
Code of practice for laying
burnt clay brick flooring
1661 : 1972
6061
Code of practice for
construction of floor and
roof with joists and filler
2114: 1984
blocks
(Part 1) : 1971
With hollow concrete filler
blocks
2115: 1980
(Part 2): 1981
With hollow clay filler
blocks (first revision)
(Part 3): 1981
Precast hollow clay blocks
joists and hollow clay filler
blocks
2338
(Part 4): 1981
With precast hollow clay
(Part 1) : 1967
block slab panels
(Part 2) : 1967
6332 : 1984
Code of practice for
2394 : 1984
construction of floors and
roofs using precast doubly-
curved shell units (first
revision)
2395
9472 : 1980
Code of practice for laying
mosaic parquet flooring
10297 : 1982
Code of practice for design
and construction of floors
(Part 1) : 1994
and roofs using precast
(Part 2) : 1994
reinforced/pre stressed
2402 : 1963
concrete ribbed or cored
slab units
2441 : 1984
10440 : 1983
Code of practice for
construction of reinforced
brick and RBC floors and
roofs
2524
10505 : 1983
Code of practice for
construction of floors and
roofs using precast
(Part 1) : 1968
concrete waffle units
(Part 2) : 1968
g) Finishes
3036 : 1992
1346 : 1991 Code of practice for
waterproofing of roofs with
bitumen felts (third revision)
1414 : 1989 Code of practice for fixing
wall coverings
1477 Code of practice for
painting of ferrous metals
in buildings
3067 : 1988
Title
Pretreatment (first revision)
Painting (first revision)
Code of practice for laying
damp-proofing treatment
using bitumen felts (second
revision)
Code of practice for
application of cement and
cement lime plaster finishes
(first revision)
Code of practice for laying
in-situ terrazzo floor finish
(first revision)
Code of practice for flat-
roof finish: Mud PHUSKA
(second revision)
Code of practice for
finishing of wood and
wood based materials
Operations and wodananship
Schedules
Code of practice for
application of lime plaster
finish (first revision)
Code of practice for
painting concrete, masonry
and plaster surfaces
Operations and workmanship
(first revision)
Schedule (first revision)
Code of practice for
external rendered finishes
Code of practice for fixing
ceiling covering (first
revision)
Code of practice for
painting of non-ferrous
metals in buildings:
Pre-treatment
Painting
Code of practice for laying
lime concrete for a water-
proofed roof finish (second
revision)
Code of practice for general
design details and
preparatory work for damp-
proofing and waterproofing
of buildings (first revision)
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
63
IS No.
Title
IS No.
3140: 1965
Code of practice for
painting asbestos cement
building products
3114: 1994
3548 : 1988
Code of practice for glazing
in building (first revision)
4127 : 1983
4101
Code of practice for
external facing and
5329 : 1983
veneers:
(Part 1) : 1967
Stone facing
(Part 2) ; 1967
Cement concrete facing
5822 : 1994
(Part 3) ; 1985
wall tiling and mosaics
(first revision)
4365 : 1967
Code of practice for
application of bitumen
mastic for waterproofing of
roofs
6530 : 1972
4597 : 1968
Code of practice for
finishing of wood and
wood based products with
7634
nitrocellulose and cold
(Part 1) : 1975
catalysed materials
4631 : 1986
Code of practice for laying
of epoxy resin floor
(Part 2) : 1975
toppings (first revision)
(Part 3) : 2003
5491 : 1969
Code of practice for laying
in-situ granolithic concrete
j) Measurements
floor topping
6278 : 1971
Code of practice for white-
washing and colour washing
1200
6494 : 1988
Code of practice for water
proofing of underground
(Part 1) : 1992
water reservoirs and
(Part 2) : 1974
swimming pools (first
revision)
(Part 3) : 1976
7198: 1974
Code of practice for damp-
proofing using bitumen
(Part 4)1976
mastic
(Part 5): 1982
7290 : 1979
Recommendations for use
of polyethylene film for
(Part 6) : 1974
waterproofing of roofs
(Part 7) : 1972
(first revision)
(Part 8) : 1993
9918 : 1981
Code of practice for in-situ
waterproofing and damp-
proofing treatments with
(Part 9) : 1973
glass fibre tissue reinforced
bitumen
(Part 10) : 1973
h) Piping
(Part 11): 1977
783 : 1985
Code of practice for laying
of concrete pipes (first
revision)
(Part 12) : 1976
Title
Code of practice for laying
of cast iron pipes (second
revision)
Code of practice for laying
of glazed stoneware pipes
(first revision)
Code of practice for sanitary
pipe work above ground for
buildings (first revision)
Code of practice for laying
of welded steel pipes
for water supply (second
revision)
Code of practice for laying
of asbestos cement pressure
pipes
Code of practice for plastics
pipe work for portable
water supplies:
Choice of materials and
general recommendations
Laying and jointing
polyethylene (PE) pipes
Laying and jointing of
unplasticized PVC pipes
Method of measurement
of building and civil
engineering works:
Earthwork (fourth revision)
Concrete work (third
revision)
Brickwork (third revision)
Stone masonry (third
revision)
Formwork (third revision)
Refactory work (second
revision)
/Hardware (second revision)
Steel work and iron work
(fourth revision)
Roof covering (including
cladding) (second revision)
Ceiling and linings (second
revision)
Paving, floor finishes dado
and skirting (third revision)
Plastering and pointing
(third revision)
64
NATIONAL BUILDING CODE OF INDIA
IS No.
(Part 13) : 1994
(Part 14) : 1984
(Part 15) : 1987
(Part 16) : 1979
(Part 17) : 1985
(Part 18); 1974
(Part 19) : 1981
(Part 20): 1981
, (Part 21): 1973
(Part 23) : 1988
(Part 24): 1983
3861 : 2002
k) Others
1081 : 1960
1649 : 1962
1946 : 1961
2470
(Part 1) : 1985
(Part 2) : 1985
Title
White washing, colour
washing, distempering and
painting of building
surfaces (fifth revision)
Glazing (third revision)
Paining, polishing,
varnishing, etc (fourth
revision)
Laying of water and sewer
lines including appurtenant
items (third revision)
Roadwork including air
field pavements (third
revision)
Demolition and dismantling
(third revision)
Water supply, plumbing
and drains (third revision)
Laying of gas and oil pipe
lines (third revision)
Woodwork and joinery
(second revision)
Piling (fourth revision)
Well foundations (third
revision)
Method of measurement of
plinth, carpet and rentable
areas of buildings (second
revision)
Code of practice for fixing
and glazing of metal (steel
and aluminium) doors,
windows and ventilators
Code of practice for design
and construction of flues
and chimneys for domestic
heating appliances
Code of practice for use of
fixing devices in walls,
ceilings and floors of solid
construction
Code of practice for
installation of septic tanks:
Design criteria and
construction (second
revision)
Secondary treatment and
disposal of septic tank
effluent (second revision)
IS No.
2527 : 1984
3414:1968
3548 : 1988
3558 : 1983
3935 : 1966
4326 : 1993
4913 : 1968
6313
(Part 1) : 1981
(Part 2) : 2001
(Part 3): 2001
6924 : 1973
7246 : 1974
8147 : 1976
(2) 13416
(Part 5) : 1994
(3) 11769
(Part 1) : 1987
Title
Code of practice for fixing
rain-water gutters and
down pipes for roof
drainage (first revision)
Code of practice for design
and installation of joints in
buildings
Code of practice for glazing
in buildings (first revision)
Code of practice for use of
immersion vibrators for
consolidating concrete
(first revision)
Code of practice for
composite construction
Code of practice for
earthquake resistant design
and construction of
buildings (second revision)
Code of practice for
selection, installation and
maintenance of timber
doors and windows
Code of practice for anti-
termite measures in
buildings:
Constructional measures
(first revision)
Pre-constructional chemical
treatment measures (second
revision)
Treatment for existing
buildings (second revision)
Code of practice for the
construction of refuse
chutes in multistoreyed
buildings
Recommendation for use
of table vibrators for
consolidating concrete
Code of practice for use of
aluminium alloys in
structures
Recommendations for
preventive measure against
hazards at workplaces:
Part 5 Fire protection
Guidelines for safe use of
products containing
asbestos: Part 1 Asbestos
cement products
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
65
IS No.
(4) 2190 : 1992
(5) 8758 : 1993
(6) 10439 : 1983
14687 : 1999
(7) 3764 : 1992
(8) 4138 : 1977
(9) 2925 : 1984
(10) 2750: 1964
(11) 3696
(Part 1) : 1987
(12) 3696
(Part 2): 1991
(13) 4912: 1978
(14) 11461: 1985
(15) 1179: 1967
(16) 5983 : 1980
(17) 2361 : 2002
(18) 11057: 1984
(19) 3016: 1982
(20) 1084 : 1994
Title
Code of practice for
selection, installation and
maintenance of portable
first-aid fire extinguishers
(third revision)
Recommendations for fire
precautionary measures in
construction of temporary
structures and pandals (first
revision)
Code of practice patent
glazing
Guidelines for falsework
for concrete structures
Safety code for excavation
work (first revision)
Safety code for working
in compressed air (first
revision)
Specification for industrial
safety helmets (second
revision)
Specification for steel
scaffoldings
Safety code for scaffolds
and ladders: Part 1 Scaffolds
Safety code for scaffolds
and ladders: Part 2 Ladders
Safety requirements for
floors and wall openings,
railing and toe boards (first
revision)
Code of practice for
compressor safety
Specification for equipment
for eye and face protection
during welding (first
revision)
Specification for eye-
protectors (first revision)
Specification for bull-dog
grips (third revision)
Specification for industrial
safety nets
Code of practice for fire
precautions in welding and
cutting operations (first
revision)
Specification for manila
ropes (fourth revision)
IS No.
2266 : 2002
(21) 818:1968
(22) 5916:1970
(23) 13416
(Part 4) : 1994
(24) 2171 : 1999
(25) 819:1957
1261 : 1959
3016 : 1982
4081 : 1986
4138: 1977
9595 : 1996
10178 : 1995
(26) 3844 : 1989
5290 : 1993
Title
Specification for steel
wire ropes for general
engineering purposes (forth
revision)
Code of practice for safety
and health requirements in
electric and gas welding
and cutting operations (first
revision)
Safety code for
constructions involving use
of hot bituminous materials
Recommendations for
preventive measure against
hazards at workplaces:
Part 4 Timber structure
Specification for portable
fire extinguishers, dry
powder (Cartridge type)
(third revision)
Code of practice for
resistance spot welding for
light assemblies in mild
steel
Code of practice for seam
welding in mild steel
Code of practice for fire
precautions in welding and
cutting operations (first
revision)
Safety code for blasting and
related drilling operations
(first revision)
Safety code for working in
compressed gas (first
revision)
Recommendations for
metal arc welding of carbon
and carbon manganese
steels (first revision)
Recommended procedure
for C0 2 gas shielded metal-
arc welding of structural
steels (first revision)
Code of practice for
installation and maintenance
of internal fire hydrants and
hose reels on premises (first
revision)
Specification for landing
valves (third revision)
66
NATIONAL BUILDING CODE OF INDIA
IS No.
(27) 13416
(Part 2): 1992
(28) 13416
(Part 1) : 1992
(29) 13416
(Part 3) : 1994
(30) 274
(Part 1) : 1981
(Part 2): 1981
663 : 1980
704 : 1984
841 : 1983
844
(Part 2) : 1979
(Part 3) : 1979
1630 : 1984
1759 : 1986
1791 : 1985
1930 : 1995
1931 :2000
2028 : 2004
Title
Recommendation for
preventive measures
against hazards at work
places: Part 2 Fall prevention
Recommendation for
preventive measures
against hazards at work
places: Part 1 Falling
material hazard prevention
Recommendation for
preventive measures against
hazards at work places:
Part 3 Disposal of debris
Specification for shovels:
General purpose shovels
(third revision)
Heat-treated shovels (third
revision)
Specification for adzes
(second revision)
Specification for crow bars
and claw bars (second
revision)
Specification for steel
hammers (second revision)
Specification for screw
drivers:
Dimensions (second
revision)
Dimensions for screw
drivers for recessed head
screws (second revision)
Specification for mason's
tools for plaster work and
pointing work (first
revision)
Specification for
POWRAHS (second
revision)
Specification for batch type
concrete mixers (second
revision)
Specification for chisels
and gauges (second
revision)
Specification for engineer* s
files (third revision)
Specification for open jaw
wrenches (spanners)
(fourth revision)
IS No.
2029:
1998
2030:
1989
2094
(Parti): 1996
(Part 2): 1999
(Part 3): 1999
2431:
1963
2438:
1963
2439:
:1963
2505:
: 1992
2506:
:1985
2514
:1963
2587
:1975
2588 : 1975
2722 : 1964
2852 : 1998
3066 : 1965
3251 : 1965
3365 : 1965
3559 : 1966
Title
Specification for ring
wrenches (spanners)
(fourth revision)
Specification for box
spanners (second revision)
Specification for heater for
bitumen (tar) and emulsion
(second revision):
Specification (second
revision)
Bitumen sprayer (third
revision)
Emulsion (third revision)
Specification for steel
wheel barrows (single
wheel-type)
Specification for roller pan
mixer
Specification for metal
hand rollers (fixed-weight
type)
Specification for concrete
vibrators, immersion type
(general requirements)
General requirements for
screed board concrete
vibrators (first revision)
Specification for concrete
vibrating tables
Specification for pipes
vices (open side type and
fixed sides type) (first
revision)
Specification for
blacksmith's vices (first
revision)
Specification for portable
swing weigh batchers for
concrete (single and double
.bucket type)
Specification for carpenters
augers (first revision)
Specification for hot
asphalt mixing plants
Specification for asphalt
paver finisher
Specification for floor
polishing machines
Specification for pneumatic
concrete breakers
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
67
IS No.
3587 : 1986
3650: 1981
3938 : 1983
4003
(Part 1) : 1978
(Part 2) : 1986
4017 : 1992
4057 : 1986
4095 : 1991
4183 : 1967
4184: 1967
4508 : 1992
4656 : 1968
4915 : 1968
5066 : 1969
5067 : 1969
5087 : 1969
5098 : 1969
5123 : 1969
5169 : 1986
5200 : 1998
5658 : 1990
5663 : 1970
Title
Specification for rasps
(second revision)
Specification for
combination side cutting
pliers (second revision)
Specification for electric
wire rope hoists (second
revision)
Specification for pipe
wrenches
General purposes (first
revision)
Heavy duty (first revision)
Specification for carpenters
squares (first revision)
Specification for carpenters
adjustable metal bodied
bench planes (first revision)
Specification for pincers
(second revision)
Specification for metal
hand rammers
Specification for steel wheel
barrows (with two wheels)
Specification for open
ended slugging wrenches
(spanners) (first revision)
Specification for form
vibrators for concrete
Specification for welders
chipping hammer
Specification for glass
pliers
Specification for fencing
pliers
Specification for wire
stripping pliers
Specification for cross cut
and rip saws
Specification for tenon and
dovetail saws
Specification for hack-saw
frames (first revision)
Specification for bolt
clippers (first revision)
Specification for snipenose
pliers (first revision)
Specification for brick and
mason's chisels
IS No.
Title
5684:
1970
Specification for pipe vices
(chain type)
5697:
1970
Specification for ripping
chisels
5889:
1994
Specification for vibratory
plate compactor (first
revision)
5890:
1970
Specification for mobile
hot mix asphalt plants, light
duty
5891 :
1970
Specification for hand-
operated concrete mixer
5995:
1971
Specification for pipe grip
pliers
6007:
1971
Specification for pipe vices
(hinged type)
6078:
1986
Specification for line man' s
pliers (second revision)
6087:
1971
Specification for metal
cutting shears
6118:
1991
Specification for multiple
slip joint pliers (first
revision)
6149:
: 1984
Specification for single
ended open jaw adjustable
wrenches (first revision)
6375:
: 1991
Specification for wood
splitting wedges (first
revision)
6389:
:1998
Specification for
combination wrenches with
equal openings (second
revision)
6428:
: 1972
Specification for pile frame
6430:
: 1985
Specification for mobile
air compressor for
construction purposes (first
revision)
6433;
: 1972
Specification for guniting
equipment
6546:
: 1989
Specification for claw
hammers (first revision)
6836
:1973
Specification for hand
snaps and set-ups for solid
rivets
6837
: 1973
Specification for three
wheel type pipe cutter
6841
: 1973
Specification for wrecking
bars
6861
:1973
Specification for engineers'
scrapers
68
NATIONAL BUILDING CODE OF INDIA
IS No.
Title
IS No.
6881 :
1973
Specification for link type
(32) 15183
pipe cutters
(Part 3) : 2002
6891 :
1973
Specification for carpenter' s
auger bits
(33) 15183
6892:
1973
Specification for
blacksmith's brick-iron
(Part 2) : 2002
7041 :
1973
Specification for carpenter' s
plain brace
(34) 13935 : 1993
7042:
1973
Specification for carpenter' s
ratchet brace
(35) 13828 : 1993
7077 :
: 1973
Specification for bending
bars
7958:
: 1976
Specification for hand vices
8202
: 1994
Specification for carpenter' s
wooden bodied planes (first
revision)
(36) 13827 : 1993
8671 :
: 1977
Specification for nail puller
(37) 4130: 1991
(31) 7293
: 1974
Safety code for working with
construction machinery
Title
Maintenance management
for buildings — Guidelines:
Part 3 Labour
Maintenance management
for buildings — Guidelines:
Part 2 Finance
Guidelines for repair and
seismic strengthening of
buildings
Improving earthquake
resistance of low strength
masonry buildings —
Guidelines
Improving earthquake
resistance of earthen
buildings — Guidelines
Safety code for demolition
of buildings (second
revision)
PART 7 CONSTRUCTIONAL PRACTICES AND SAFETY
69
NATIONAL BUILDING CODE OF INDIA
PART 8 BUILDING SERVICES
Section 1 Lighting and Ventilation
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 ORIENTATION OF BUILDING
4 LIGHTING
5 VENTILATION
ANNEX A SKY COMPONENT TABLES
LIST OF STANDARDS
5
5
8
11
35
43
47
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
Illumination levels for different tasks are recommended to be achieved either by daylighting or artificial lighting
or a combination of both. This Section, read together with Part 8 'Building Services, Section 2 Electrical and
Allied Installations', adequately covers the illumination levels required and methods of achieving the same.
Ventilation requirements to maintain air quality and control body odours in terms of air changes per hour and to
ensure thermal comfort and heat balance of body are laid for different occupancies and the methods of achieving
the same by natural means are covered in this Section. The provisions on mechanical ventilation are covered in
Part 8 'Building Services, Section 3 Air Conditioning, Heating and Mechanical Ventilation'.
Climatic factors which normally help in deciding the orientation of the buildings to get desirable benefits of
lighting and ventilation inside the buildings are also covered in this Section.
This Section was first published in 1970. The first revision of the Section was brought out in 1983. In this
revision, some provisions have been updated based on the information given in the SP 41 : 1987 'Handbook on
functional requirements of buildings (other than industrial buildings)'; other major changes in this revision are:
a) Rationalization of definitions and inclusion of definitions for some more terms.
b) A climatic classification map of India based on a new criteria has been included.
c) Data on total solar radiations incident on various surfaces of buildings for summer and winter seasons
have been updated.
d) Design guidelines for natural ventilation have been included.
e) For guidelines on mechanical ventilation, reference to Part 8 'Building Services, Section 3 Air
Conditioning, Heating and Mechanical Ventilation' has been made, where these provisions have now
been covered exhaustively.
f) Rationalized method for estimation of desired capacity of ceiling fans and their optimum height above
the floor for rooms of different sizes have been included.
g) Design sky illuminance values for different climatic zones of India have been incorporated.
Energy efficiency is an important aspect being taken care of in this revision of the Code. Accordingly, the
relevant requirements for energy efficient system for lighting and ventilation have been duly included in the
concerned provisions under this Section.
The provisions of this Section are without prejudice to the various Acts, Rules and Regulations including the
Factories Act, 1948 and Rules and Regulations framed thereunder.
The information contained in this Section in largely based on the following Indian Standards/Special Publications:
IS 2440 : 1975 Guide for daylighting of buildings (second revision)
IS 3103 : 1975 Code of practice for industrial ventilation (first revision)
IS 3362 : 1977 Code of practice for natural ventilation of residential buildings (first revision)
IS 3646 Code of practice for interior illumination: Part 1 General requirements and
(Part 1) : 1992 recommendations for building interiors (first revision)
IS 7662 Recommendations for orientation of buildings: Part 1 Non-industrial buildings
(Part 1) : 1974
IS 1 1907 : 1986 Recommendations for calculation of solar radiation on buildings
SP 32 : 1986 Handbook on functional requirements of industrial buildings (lighting and ventilation)
SP 41 : 1987 Handbook on functional requirements of buildings other than industrial buildings
Provisions given in National Lighting Code (under preparation) may also be referred.
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION 3
The following publication has also been referred to in the preparation of this Section:
Report on energy conservation in buildings, submitted to Department of Power, Ministry of Energy by
Central Building Research Institute, Roorkee.
All standards, whether given herein above or cross-referred to in the main text of this Section, are subject to
revision. The parties to agreement based on this Section are encouraged to investigate the possibility of applying
the most recent editions of the standards.
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 8 BUILDING SERVICES
Section 1 Lighting and Ventilation
1 SCOPE
This Section covers requirements and methods for
lighting and ventilation of buildings.
2 TERMINOLOGY
2.0 For the purpose of this Section, the following
definitions shall apply.
2.1 Lighting
2.1.1 Altitude (0) — The angular distance of any point
of celestial sphere, measured from the horizon, on the
great circle passing through the body and the zenith
(see Fig. 1).
2.1.2 Azimuth (</>) — The angle measured between
meridians passing through the north point and the point
in question (point C in Fig. 1).
MERIDIAN
REFERENCES
O -
C -
Z -
NA-
Observer's station
Celestial body
Zenith
Nadir
S - Geographical south
E - Geographical east
W - Geographical west
N - Geographical north
Fig. 1 Altitude and Azimuth of a
Celestial Body
2.1.3 Brightness Ratio or Contrast — The variations
or contrast in brightness of the details of a visual task,
such as white print on blackboard.
2.1.4 Candela (cd) — The SI unit of luminous
intensity.
Candela = 1 lumen per steradian
2.1.5 Central Field — The area of circle round the
point of fixation and its diameter, subtending an angle
of about 2° at the eye. Objects within this area are most
critically seen in both their details and colour.
2.1.6 Clear Design Sky — The distribution of
luminance of such a sky is non-uniform; the horizon
is brighter than the zenith, and when L z is the brightness
at zenith, the brightness at an altitude (0 ) in the region
away from the sun, is given by the expression:
L e = L z cosec 6
when0 lies between 15° and 90°
when# lies between 0° and 15°.
and L a is constant
2.1.7 Colour Rendering Index (CRI) — Measure of
the degree to which the psychophysical colour of an
object illuminated by the test illuminant conforms to
that of the same object illuminated by the reference
illuminant, suitable allowance having been made for
the state of chromatic adaptation.
2.1.8 Correlated Colour Temperature (CCT) (Unit:
K) — The temperature of the Planckian radiator whose
perceived colour most closely resembles that of a given
stimulus at the same brightness and under specified
viewing conditions.
2.1.9 Daylight Area — The superficial area on the
working plane illuminated to not less than a specified
daylight factor, that is, the area within the relevant
contour.
2.1.10 Daylight Factor — The measure of total
daylight illuminance at a point on a given plane
expressed as the ratio (or percentage) which the
illuminance at the point on the given plane bears to
the simultaneous illuminance on a horizontal plane due
to clear design sky at an exterior point open to the
whole sky vault, direct sunlight being excluded.
2.1.11 Daylight Penetration — The maximum
distance to which a given daylight factor contour
penetrates into a room.
2.1.12 Direct Solar Illuminance — The illuminance
from the sun without taking into account the light from
the sky.
2.1.13 External Reflected Component (ERC) — The
ratio (or percentage) of that part of the daylight
illuminance at a point on a given plane which is
received by direct reflection from external surfaces as
compared to the simultaneous exterior illuminance on
a horizontal plane from the entire hemisphere of an
unobstructed clear design sky.
2.1.14 Glare — A condition of vision in which there
is discomfort or a reduction in the ability to see
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
significant objects or both due to an unsuitable
distribution or range of luminance or due to extreme
contrasts in space and time.
2.1.15 Illuminance — At a point on a surface, the ratio
of the luminous flux incident on an infinitesimal
element of the surface containing the point under
consideration to the area of the element.
NOTE — The unit of illuminance (the measurement of
illumination) is lux which is 1 lumen per square metre.
2.1.16 Internal Reflected Component (IRC) — The
ratio (or percentage) of that part of the daylight
illuminance at a point in a given plane which is received
by direct reflection or inter-reflection from the internal
surfaces as compared to the simultaneous exterior
illuminance on a horizontal plane due to the entire
hemisphere of an unobstructed clear design sky.
2.1.17 Light Output Ratio (LOR) or Efficiency ( rj) —
The ratio of the luminous flux emitted from the
luminaire to that emitted from the lamp(s) (nominal
luminous flux). It is expressed in percent.
2.1.18 Lumen (Im) — SI unit of luminous flux. The
luminous flux emitted within unit solid angle (one
steradian) by a point source having a uniform intensity
of one candela.
2.1.19 Luminance (At a point of a Surface in a Given
Direction) (Brightness) — The quotient of the
luminous intensity in the given direction of an
infinitesimal element of the surface containing the
point under consideration by the orthogonally
projected area of the element on a plane perpendicular
to the given direction. The unit is candela per square
metre (cd/m 2 ).
2.1.20 Luminous Flux (</>) — The quantity characteristic
of radiant flux which expresses its capacity to produce
visual sensation evaluated according to the values
of relative luminous efficiency for the light adapted
eye:
a) Effective luminous flux ( </> n ) — Total luminous
flux which reaches the working plane.
b) Nominal luminous flux ( </> o ) — Total luminous
flux of the light sources in the interior.
2.1.21 Maintenance Factor (d) — The ratio of the
average illuminance on the working plane after a
certain period of use of a lighting installation to the
average illuminance obtained under the same
conditions for a new installation.
2.1.22 Meridian — It is the great circle passing through
the zenith and nadir for a given point of observation.
2.1.23 North and South Points — The point in the
respective directions where the meridian cuts the
horizon.
2.1.24 Orientation of Buildings — In the case of non-
square buildings, orientation refers to the direction of
the normal to the long axis. For example, if the length
of the building is east- west, its orientation is north-
south.
2.1.25 Peripheral Field — It is the rest of the visual
field which enables the observer to be aware of the
spatial framework surrounding the object seen.
NOTE — A central part of the peripheral field, subtending an
angle of about 30° on either side of the point of fixation, is
chiefly involved in the perception of glare.
2.1.26 Reflected Glare — The variety of ill effects on
visual efficiency and comfort produced by unwanted
reflections in and around the task area.
2.1.27 Reflection Factor (Reflectance) — The ratio
of the luminous flux reflected by a body (with or
without diffusion) to the flux it receives. Some symbols
used for reflection factor are;
r c = Reflection factor of ceiling.
r w = Reflection factor of parts of the wall between
the working surface and the luminaires.
r f = Reflection factor of floor.
2.1.28 Reveal — The side of an opening for a window.
2.1.29 Room Index (£ ) — An index relating to the shape
of a rectangular interior, according to the formula:
k =
L.W
(L + W)H m
where L and W are the length and width respectively
of the interior, and H m is the mounting height, that is,
height of the fittings above the working plane.
NOTES
1 For rooms where the length exceeds 5 times the width, L
shall be taken as L = 5W.
2 If the reflection factor of the upper stretch of the walls is
less than half the reflection factor of the ceiling, for indirect or
for the greater part of indirect lighting, the value H m is measured
between the ceiling and the working plane.
2.130 Sky Component (SC) — The ratio (or percentage)
of that part of the daylight illuminance at a point on a
given plane which is received directly from the sky as
compared to the simultaneous exterior illuminance on
a horizontal plane from the entire hemisphere of an
unobstructed clear design sky.
2.1.31 Solar Load — The amount of heat received
into a building due to solar radiation which is affected
by orientation, materials of construction and reflection
of external finishes and colour.
2.1.32 Utilization Factor (Coefficient of Utilizaiton)
(fi) — The ratio of the total luminous flux which
reaches the working plane (effective luminous
NATIONAL BUILDING CODE OF INDIA
flux, n ) to the total luminous flux of the light sources
in the interior (nominal luminous flux, ).
2. 1 .33 Visual Field — The visual field in the binocular
which includes an area approximately 120° vertically
and 160° horizontally centering on the point to which
the eyes are directed. The line joining the point of
fixation and the centre of the pupil of each eye is called
its primary line of sight.
2.1.34 Working Plane — A horizontal plane at a level
at which work will normally be done (see 4.1.3.3
and 4.1.3.4).
2.2 Ventilation
2.2.1 Air Change per Hour — The amount of air
leakage into or out of a building or room in terms of
the number of building volume or room volume
exchanged.
2.2.2 Axial Flow Fan — A fan having a casing in
which the air enters and leaves the impeller in a
direction substantially parallel to its axis.
2.2.3 Centrifugal Fan — A fan in which the air leaves
the impeller in a direction substantially at right angles
to its axis.
2.2.4 Contaminants — Dusts, fumes, gases, mists,
vapours and such other substances present in air as are
likely to be injurious or offensive to the occupants.
2.2.5 Dilution Ventilation — Supply of outside air to
reduce the air-borne concentration of contaminants in
the building.
2.2.6 Dry Bulb Temperature — The temperature of
the air, read on a thermometer, taken in such a way as
to avoid errors due to radiation.
2.2.7 Effective Temperature (ET) — An arbitrary index
which combines into a single value the effect of
temperature, humidity and air movement on the
sensation of warmth or cold felt by the human body
and its numerical value is that of the temperature of
still saturated air which would induce an identical
sensation.
2.2.8 Exhaust of Air — Removal of air from a building
or a room and its disposal outside by means of a
mechanical device, such as a fan.
2.2.9 Fresh Air or Outside Air — Air of that quality,
which meets the criteria of Table 1 and in addition
shall be such that the concentration of any contaminant
in the air is limited to within one-tenth the threshold
Limit value (TLV) of that contaminant.
NOTES
1 Where it is reasonably believed that the air of quality is
unexpectable as indicated above, sampling and analysis shall
be carried out by a competent authority having jurisdiction and
if the outside air of the quality specified is not available, filtration
and other treatment devices shall be used to bring its quality to
or above the levels mentioned in Table 1.
2 The list of contaminants given in Table 1 is not exhaustive
and available special literature may be referred for data on
other contaminants.
Table 1 Maximum Allowable Contaminant
Concentrations for Ventilation Air Contaminants
Annual Average (Arithmetic Mean)
(Clause 2.2.9)
Contaminants
Annual
Average
(Arithmetic
Mean)
Short-Term
Level (Not
to exceed
More than
Once a
Year)
Averaging
Period
Hg/m 3
Hg/m 3
h
(1)
(2)
(3)
(4)
Suspended particulates
60
150
24
Sulphur oxides
80
400
24
Carbon monoxide
20000
30 000
8
Photochemical oxidant
100
500
1
Hydrocarbons (not
including methanes)
1800
4 000
3
Nitrogen oxide
200
500
24
Odour: Essentially
unobjectionable
2.2.10 General Ventilation — Ventilation, either
natural or mechanical or both, so as to improve the
general environment of the building, as opposed to
local exhaust ventilation for contamination control.
2.2.11 Globe Temperature — The temperature
measured by a thermometer whose bulb is enclosed in
a matt black painted thin copper globe of 150 mm
diameter. It combines the influence of air temperature
and thermal radiations received or emitted by the
bounding surfaces.
2.2.12 Humidification — The process whereby the
absolute humidity of the air in a building is maintained
at a higher level than that of outside air or at a level
higher than that which would prevail naturally.
2.2.13 Humidity, Absolute
vapour per unit volume.
The mass of water
2.2.14 Humidity, Relative — The ratio of the partial
pressure or density of the water vapour in the air to the
saturated pressure or density respectively of water
vapour at the same temperature.
2.2.15 Local Exhaust Ventilation — Ventilation
effected by exhaust of air through an exhaust appliance,
such as a hood with or without fan located as closely
as possible to the point at which contaminants are
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
released, so as to capture effectively the contaminants
and convey them through ducts to a safe point of
discharge.
2.2.16 Make-up Air — Outside air supplied into a
building to replace the indoor air.
2.2.17 Mechanical Ventilation — Supply of outside air
either by positive ventilation or by infiltration by
reduction of pressure inside due to exhaust of air, or
by a combination of positive ventilation and exhaust
of air.
2.2.18 Natural Ventilation — Supply of outside air
into a building through window or other openings due
to wind outside and convection effects arising from
temperature or vapour pressure differences (or both)
between inside and outside of the building.
2.2.19 Positive Ventilation — The supply of outside
air by means of a mechanical device, such as a fan.
2.2.20 Propeller Fan — A fan in which the air leaves
the impeller in a direction substantially parallel to its
axis i?sigr r i ?^r operate normally under free inlet and
outlet conditions.
2.2.21 Spray-Head System — A system of atomizing
water so as to introduce free moisture directly into a
building.
2.2.22 Stack Effect — Convection effect arising from
temperature or vapour pressure difference (or both)
between outside and inside of the room and the
difference of height between the outlet and inlet
openings.
2.2.23 Tropical Summer Index (TSI) — The temperature
of calm air at 50 percent relative humidity which
imparts the same thermal sensation as the given
environment. TSI (in °C) is express as
0.745 t +0.308 t
-2.06^/7+0.841
where
t = Globe temperature, °C;
f w = Wet bulb temperature, °C; and
v = Wind speed, m/s.
2.2.24 Threshold Limit Value (TLV) — Refers to air-
borne concentration of contaminants currently accepted
by the American Conference of Governmental
Industrial Hygienists and represents conditions under
which it is believed that nearly all occupants may be
repeatedly exposed, day after day, without adverse
effect.
2.2.25 Velocity, Capture — Air velocity at any point
in front of the exhaust hood necessary to overcome
opposing air currents and to capture the contaminants
in air at that point by causing the air to flow into the
exhaust hood.
2.2.26 Ventilation — Supply of outside air into, or
the removal of inside air from an enclosed space.
22.27 Wet Bulb Temperature — The steady temperature
finally given by a thermometer having its bulb covered
with gauze or muslin moistened with distilled water
and placed in an air stream of not less than 4.5 m/s.
3 ORIENTATION OF BUILDING
. L :, ''"!- : :■■ *■'
3.1 The chief aim of orientation of buildings is to
provide physically and psychologically comfortable
living inside the building by creating conditions which
suitably and successfully w^rd off the undesirable
effects of severe weather to a considerable extent by
judicious use of the recommendations and knowledge
of climatic factors.
3.2 Basic Zones
3.2.1 For the purpose of design of buildings, the
country may be divided into the major climatic zones
as given in Table 2, which also gives the basis of this
classification.
Table 2 Classification of
Climate
(Clause 3.2.1)
SI
Climatic
Mean Monthly
Mean Monthly
No.
Zone
Maximum
Relative Humidity
Temperature ( C C)
Percentage
(1)
(2)
(3)
(4)
i)
Hot-Dry
above 30
below 55
ii)
Warm-Humid
above30
above 55
above 25
above 75
iii)
Temperate
between 25-30
below 75
iv)
Cold
below 25
All values
v)
Composite
see 3.2.2
The climatic classification map of India is shown in
Fig. 2.
3.2.2 Each climatic zone does not have same climate
for the whole year; it has a particular season for more
than six months and may experience other seasons for
the remaining period. A climatic zone that does not
have any season for more than six months may be
called as composite zone.
3.3 Climatic Factors
From the point of view of lighting and ventilation, the
following climatic factors influence the optimum
orientation of the building:
a) solar radiation and temperature
b) relative humidity, and
c) prevailing winds.
8
NATIONAL BUILDING CODE OF INDIA
■SEES
rf-
MAP OF INDIA
SHOWING
CLIMATIC ZONES
-1/
Based upon Survey of India Outline Map printed in 1993.
© Government of India Copyright, 2005
The territorial waters of India extend into the sea to a distance of twelve nautical miles measured from the appropriate base line.
The boundary of Meghalaya shown on this map is as interpreted from the North-Eastern Areas (Reorganisation) Act, 1971, but has yet to be verified.
Responsibility for correctness of internal details shown on the map rests with the publisher.
The state boundaries between Uttaranchal & Uttar Pradesh, Bihar & Jharkhand and Chhatisgarh & Madhya Pradesh have not been verified by Governments concerned.
Fig. 2 Map of India Showing Climatic Zones
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
3.4 Solar Radiation
3.4.1 The best orientation from solar point of view
requires that the building as a whole should receive
the maximum solar radiation in winter and the
minimum in summer. For practical evaluation, it is
necessary to know the duration of sunshine, and hourly
solar intensity on the various external surfaces on
representative days of the seasons. The total direct plus
diffused diurnal solar loads per unit area on vertical
surface facing different directions are given in Table 3
for two days in the year, that is, 22 June and 22
December, representative of summer and winter, for
latitudes corresponding to some important cities all
over India. From Table 3, the total heat intake can be
calculated for all possible orientations of the building
for these extreme days of summer and winter.
3.4.1.1 Except in cold climatic zone, suitable sun-
breakers have to be provided to cut off the incursion
of direct sunlight to prevent heat radiation and to avoid
glare.
3.5 Relative Humidity and Prevailing Winds
3.5.1 The discomfort due to high relative humidity
in air when temperatures are also high can be
counteracted, to a great extent, by circulation of air
with electric fans or by ventilation. In the past,
simultaneously with heavy construction and
surrounding VERANDAHS to counter the effect of
sun's radiation, there was also an over emphasis on
prevailing winds to minimize the adverse effects of
high humidity with high temperatures. With the
introduction of electric fan to effectively circulate air
and owing to taking into account the rise in cost of
construction of buildings, it would perhaps be better
to shift the emphasis on protection from solar radiation
where temperatures are very high. When, however,
there is less diurnal variation between morning and
mean maximum temperatures along with high
humidity, as in coastal areas, the emphasis should be
on prevailing winds.
3.5.1.1 For the purpose of orientation, it is necessary
to study the velocity and direction of the wind at each
hour and in each month instead of relying on
generalizations of a month or a period or for the year
as a whole. This helps to spot the right winds for a
particular period of day or night.
3.5.1.2 It is generally found that variation up to 30°
with respect to the prevalent wind direction does not
materially affect indoor ventilation (average indoor air
speed) inside the building.
3.5.2 In hot-dry climate, advantage can be taken of
evaporative cooling in summer to cool the air before
introducing it into the building. But in warm humid
climate, it is desirable either to regulate the rate of air
movement with the aid of electric fans or to take
advantage of prevailing winds.
3.6 Aspects of Daylighting
Since the clear design sky concept for daylighting takes
care of the worst possible situation, orientation is not
Table 3 Total Solar Radiation (Direct plus Diffused) Incident on Various Surfaces of
Buildings in W/m 2 /day for Summer and Winter Seasons
(Clause 3.4.1)
Orientation
Latitude
**-_
„ ,_.,-A-
9°N
13°N
17°N
21°N
25°N
-^k
r~
N
29°N
(D
(2)
(3)
(4)
(5)
(6)
(7)
(8)
North
Summer
1494
1251
2 102
1775
2 173
1927
Winter
873
859
840
825
802
765
North -East
Summer
2 836
2717
3 144
3 092
3 294
3 189
Winter
1240
1 158
1068
1001
912
835
East
Summer
3 344
3 361
3 475
3 598
3 703
3 794
Winter
2 800
2 673
2 525
2 409
2211
2 055
South-East
Summer
2 492
2 660
2 393
2 629
2 586
2 735
Winter
3 936
3 980
3 980
3 995
3 892
3 818
South
Summer
1009
1 185
1035
1 117
1 112
1350
Winter
4 674
4 847
4 958
5 059
4 942
4 981
South-West
Summer
2 492
2 660
2 393
2 629
2 586
2 735
Winter
3 936
3 980
3 980
3 995
3 892
3 818
West
Summer
3 341
3 361
3 475
3 598
3 703
3 794
Winter
2 800
2 673
2 525
2 409
2211
2 055
North-West
Summer
2 836
2 717
3 144
3 092
3 294
3 189
Winter
1240
1 158
1068
1001
912
835
Horizontal
Summer
8 107
8 139
8 379
8 553
8 817
8 863
Winter
6 409
6 040
5 615
5 231
4 748
4 281
10
NATIONAL BUILDING CODE OF INDIA
a major problem for daylighting in buildings, except
that direct sunshine and glare should be avoided.
However, due allowance should be given to the mutual
shading effects of opposite facades.
3.7 Planting of Trees
Planting of trees in streets and in open spaces should
be done carefully to take advantage of both shades and
sunshine without handicapping the flow of natural
winds. Their advantage in abating glare and in
providing cool and/or warm pockets in developed areas
should also be taken. Some trees shed leaves in winter
while retaining thick foliage in summer. Such trees
will be very advantageous, particularly where southern
and western exposures are concerned, by allowing
maximum sun during winter and effectively blocking
it in summer.
3.8 For detailed information regarding orientation of
buildings and recommendations for various climatic
zones of country, reference may be made to good
practice [8-1(1)].
4 LIGHTING
4.1 Principles of Lighting
4.1.1 Aims of Good Lighting
Good lighting is necessary for all buildings and has
three primary aims. The first aim is to promote work
and other activities carried out within the building; the
second aim is to promote the safety of the people using
the building; and the third aim is to create, in
conjunction with the structure and decoration, a
pleasing environment conducive to interest of the
occupants and a sense of their well-being.
4.1.1.1 Realization of these aims involves:
a) careful planning of the brightness and colour
pattern within both the working areas and the
surroundings so that attention is drawn
naturally to the important areas, detail is seen
quickly and accurately and the room is free
from any sense of gloom or monotony
(see 4.1.3);
b) using directional lighting where appropriate
to assist perception of task detail and to give
good modeling;
c) controlling direct and reflected glare from
light sources to eliminate visual discomfort;
d) in artificial lighting installations, minimizing
flicker from certain types of lamps and paying
attention to the colour rendering properties
of the light;
e) correlating lighting throughout the building to
prevent excessive differences between adjacent
areas so as to reduce the risk of accidents; and
f) installation of emergency lighting systems,
where necessary.
4.1.2 Planning the Brightness Pattern
The brightness pattern seen within an interior may be
considered as composed of three main parts — the task
itself, immediate background of the task and the general
surroundings of walls, ceiling, floor, equipment and
furnishings.
4.1.2.1 Inoccupations where the visual demands are
small, the levels of illumination derived from a
criterion of visual performance alone may be too low
to satisfy the other requirements. For such situations,
therefore, illuminance recommendations are based on
standards of welfare, safety and amenity judged
appropriate to the occupations; they are also sufficient
to give these tasks brightness which ensured that the
visual performance exceeds the specified minimum.
Unless there are special circumstances associated
with the occupation, it is recommended that the
illuminance of all working areas within a building
should generally be 150 lux, even though the visual
demands of the occupation might be satisfied by lower
values.
4.1.2.2 Where work takes place over the whole
utilizable area of room, the illumination over that area
should be reasonably uniform and it is recommended
that the uniformity ratio (minimum illuminance divided
by average illuminance levels) should be not less than
0.7 for the working area.
4.1.2.3 When the task brightness appropriate to an
occupation has been determined, the brightness of the
other parts of the room should be planned to give a
proper emphasis to visual comfort and interest.
A general guide for the brightness relationship within
the normal field of vision should be as follows:
a) For high task brightness Maximum
(above 100 cd/m 2 )
1) Between the visual task 3 to 1
and the adjacent areas
like table tops
2) Between the visual task 10 to 1
and the remote areas of
the room
b) For low and medium task brightness (below
100 cd/m 2 ): The task should be brighter than
both the background and the surroundings;
the lower the task brightness, the less critical
is the relationship.
4.1.3 Recommended Values of Illuminance
Table 4 gives recommended values of illuminance
commensurate with the general standards of lighting
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
11
described in this section and related to many
occupations and buildings; These are valid under most
of the conditions whether the illumination is by
daylighting, artificial lighting or a combination of the
two. The great variety of visual tasks makes it
impossible to list them all and those given should be
regarded as representing types of task.
4.1.3.1 The different locations and tasks are grouped
within the following four sections:
a) Industrial buildings and process;
b) Offices, schools and public buildings;
c) Surgeries and hospitals; and
d) Hotels, restaurants, shops and homes.
4.1.3.2 The illumination levels recommended in
Table 4 are those to be maintained at all time on the
task. As circumstances may be significantly different
for different interiors used for the same application or
for different conditions for the same kind of activity, a
range of illuminances is recommended for each type
of interior or activity instead of a single value of
illuminance. Each range consists of three sucessive
steps of the recommended scale of illuminances. For
working interiors the middle value of each range
represents the recommended service illuminance that
would be used unless one or more of the factors
mentioned below apply.
4.1.3.2.1 The higher value of the range should be used
when:
a) unusually low reflectances or contrasts are
present in the task;
b) errors are costly to rectify;
c) visual work is critical;
d) accuracy or higher productivity is of great
importance; and
e) the visual capacity of the worker makes it
ncessary.
4.1.3.2.2 The lower value of the range may be used
when:
a) reflectances or contrast are unusually high;
b) speed and accuracy is not important; and
c) the task is executed only occasionally.
4.1.3.3 Where a visual task is required to be carried
out throughout an interior, general illumination level
to the recommended value on the working plane is
necessary; where the precise height and location of
the task are not known or cannot be easily specified,
the recommended value is that on horizontal plane
850 mm above floor level.
NOTE — For an industrial task, working plane for the purpose
of general illumination levels is that on a work place which is
generally 750 mm above the floor level. For certain purposes,
such as viewing the objects of arts, the illumination levels
recommended are for the vertical plane at which the art pieces
are placed.
4.1.3.4 Where the task is localized, the recommended
value is that for the task only; it need not, and
sometimes should not, be the general level of
illumination used throughout the interior. Some
processes, such as industrial inspection process, call
for lighting of specialized design, in which case the
level of illumination is only one of the several factors
to be taken into account
4.1.4 Glare
Excessive contrast or abrupt and large changes in
brightness produce the effect of glare. When glare is
present, the efficiency of vision is reduced and small
details or subtle changes in scene cannot be perceived.
It may be
a) direct glare due to light sources within the
field of vision,
b) reflected glare due to reflections from light
sources or surfaces of excessive brightness,
and
c) veiling glare where the peripheral field is
comparatively very bright.
4.1.4.1 An example of glare sources in daylighting is
the view of the bright sky through a window or
skylight, especially when the surrounding wall or
ceiling is comparatively dark or weakly illuminated.
Glare can be minimized in this case either by shielding
the open sky from direct sight by louvers, external
hoods or deep reveals, curtains or other shading devices
or by cross lighting the surroundings to a comparable
level. A gradual transition of brightness from one
portion to the other within the field of vision always
avoids or minimizes the glare discomfort.
4.1.5 Lighting for Movement about a Building
Most buildings are complexes of working areas and
other areas, such as passages, corridors, stairways,
lobbies and entrances. The lighting of all these areas
should be properly correlated to give safe movement
within the building at all times.
4.1.5.1 Corridors, passages and stairways
Accidents may result if people leave a well-lighted
working area and pass immediately into corridors or
on to stairways where the lighting is inadequate, as
the time needed for adaptation to the lower level may
be too long to permit obstacles or the treads of stairs
to be seen sufficiently quickly. For the same reason, it
is desirable that the illumination level of rooms which
open off a working area should be fairly high even
though the rooms may be used only occasionally.
12
NATIONAL BUILDING CODE OF INDIA
Table 4 Recommended Values of Illuminance
(Clauses 4.1.3, 4.1.3.2, 4.3.2 and 4.3.2.1)
SI No.
(1)
Type of Interior or Activity
(2)
Range of Service Quality Class
niuminance of Direct Glare
in Lux Limitation
(3)
(4)
Remarks
(5)
1
AGRICULTURE AND HORTICULTURE
1.1
Inspection of Farm Produce where Colour is
Important
300-500-750
1
Local lighting may be appropriate
Other Important Tasks
200-300-50Q
2
Local lighting may be appropriate
1.2
Farm Workshops
- '. •
1.2.1
General
50-100-150
3
1.2.2
Workbench or machine
200-300-500
2
Local or portable lighting may be
appropriate
1.3
Milk Premises
50-100-150
3
1.4
Sick Animal Pets, Calf Nurseries
30-50-100
3
1.5
Other Firm and Horticultural Buildings
20-30-50
3
2
COAL MINING (SURFACE BUILDINGS)
2.1
Coal Preparation Plant
2.1.1
Walkways, floors under conveyors
30-50-100
3
2.1.2
Wagon loading, bunkers
30-50-100
3
2.1.3
Elevators, chute transfer pits, washbox area
50-100-150
3
2.1.4
Drum filters, screen, rotating shafts
100-150-200
3
2.1.5
Picking belts
150-200-300
3
Directional and colour properties
of lighting may be important for
easy recognition of coal and rock
2.2
Lamp Rooms
2.2.1
Repair section
200-300-500
2
2.2.2
Other areas
100-150-200
3
2.3
Weight Cabins, Fan Houses
100-150-200
3
2.4
Winding Houses
100-150-200
3
3 ELECTRICITY GENERATION,
TRANSMISSION AND DISTRIBUTION
3.1 General Plant
3.1.1 Turbine houses (operating floor)
3.1.2 Boiler and turbine house basements
3.1.3 Boiler houses, platforms, areas around burners
3.1.4 Switch rooms, meter rooms, oil plant rooms, HV
substations (indoor)
3.1.5 Control rooms
3.1.6 Relay and telecommunication rooms
3.1.7 Diesel generator rooms, compressor rooms
3.1.8 Pump houses, water treatment plant houses
3.1.9 Battery rooms, chargers, rectifiers
3.1.10 Precipitator chambers, platforms, etc
3.1.11 Cable tunnels and basements, circulating water
culverts and screen chambers, storage tanks
(indoor), operating areas and filling points at
outdoor tanks
3.2 Coal Plant
3.2.1 Conveyors, gantries, junction towers, unloading
hoppers, ash handling plants, settling pits, dust
hoppers outlets
3.2.2 Other areas where operators may be in attendance
3.3 Nuclear Plants
Gas circulation bays, reactor area, boiler platform,
reactor charges and discharge face
4 METAL MANUFACTURE
4.1 Iron Making
4.1.1 Sinter plant:
Plant floor
150-200-300
2
50-100-150
3
50-100-150
3
100-150-200
2
200-300-500
1
Localized lighting of control
display and the control desks may
be appropriate
200-300-500
2
100-150-200
3
100-150-200
3
50-100-150
3
50-100-150
3
30-50-100
3
50-100-150
100-150-200
100-150-200
150-200-300
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
13
Table 4 — Continued
(l)
(2)
(3)
(4)
(5)
4.1.2
4.2
4.2.1
4.2.2
4.2.2.1
4.2.2.2
4.2.2.3
4.2.2.4
4.3
4.3.1
Mixer drum, fan house, screen houses, coolers,
transfer stations
Furnaces, cupola:
General
Control platforms
Conveyor galleries, walkways
Steel Making
Electric melting shops
Basic oxygen steel making plants
General
Convertor floor, teeming bay
Control platforms
Scrap bays
Metal Forming and Treatment
Ingot stripping, soaking pits, annealing and heat
treatment bays, acid recovery plant Picking
and cleaning bays, roughing mills, cold mills,
finishing mills, tinning and galvanizing lines,
cut up and rewind lines
100-150-200
3
100-150-200
200-300-500
30-50-100
3
2
3
150-200-300
■• 3
100-150-200
150-200-300
200-300-500
100-150-200
3
3
2
3
150-200-300
3
Local lighting may be appropriate
Local lighting may be appropriate
4.3.2
General
100-150-200
3
4.3.3
Control platforms
200-300-500
2
Local lighting may be appropriate
4.3.4
Wire mills, product finishing, steel inspection
. and treatment
200-300-500
3
4.3.5
Plate/strip inspection
300-500-700
2
4.3.6
Inspection of tin plate, stainless steel, etc
Special lighting to reveal faults in
the specular surface of the
material will be required
4.4
Foundries
4.4.1
Automatic Plant
4,4.1.1
Without manual operation
30-50-100
3
4.4.1.2
With occasional manual operation
100-150-200
3
4.4.1.3
With continuous manual operation
150-200-300
3
4.4.1.4
Control room
200-300-500
1
Localized lighting of the control
display and the control desks may
be appropriate
4.4.1.5
Control platforms
200-300-500
2
4.4.2
Non-automatic plants
4.4.2.1
Charging floor, pouring, shaking out, cleaning,
grinding fettling
200-300-500
3
4.4.2.2
Rough moulding, rough core making
200-300-500
3
4.4.2.3
Fine moulding, fine core making
300-500-750
2
4.4.2.4
Inspection
300-500-750
2
4.5
Forges (Severe vibration is likely to occur)
4.5.1
General
200-300-500
2
4.5.2
Inspection
300-500-750
2
5
CERAMICS
5.1 Concrete products
Mixing, casting, cleaning
5.2 Potteries
5.2.1 Grinding, moulding, pressing, cleaning,
trimming, glazing, firing
5.2.2 Enamelling, colouring
5.3 Glass Works
5.3.1 Furnace rooms, bending, annealing
5.3.2 Mixing rooms, forming, cutting, grinding,
polishing, toughening
5.3.3 Beveling, decorative cutting, etching, silvering
5.3.4 Inspection
150-200-300
3
200-300-500
3
500-750-1000
1
100-150-200
3
200-300-500
3
300-500-750
2
300-500-750
2
14
NATIONAL BUILDING CODE OF INDIA
Table 4 — Continued
(l)
(2)
(3)
(4)
(5)
6 CHEMICALS
6.1 Petroleum, Chemical and Petrochemical Works
6.1.1 Exterior walkways, platforms, stairs and ladders 30-50-100
6.1.2 Exterior pump and valve areas 50-100-150
6.1.3 Pump and compressor houses 100-150-200
6.1.4 Process plant with remote control 30-50-100
6.1.5 Process plant requiring occasional manual 50-100-150
intervention
6.1.6 Permanently occupied work stations in process 150-200-300
plant
6.1.7 Control rooms for process plant 200-300-500
6.2 Pharmaceutial Manufacturer and Fine Chemicals
Manufacturer
6.2.1 Pharmaceutical manufacturer
Grinding, granulating, mixing, drying, tableting, 300-500-750
sterilizing, washing, preparation of solutions,
filling, capping, wrapping, hardening
6.2.2
6.2.2.1
6.2.2.2
6.2.2.3
6.2.2.4
Fine chemical manufacture
Exterior walkways, platforms, stairs and ladders
Process plant
Fine chemical finishing
Inspection
30-50-100
50-100-150
300-500-750
300-500-750
3
3
2
1
Local lighting may be appropriate
6.3
6.3.1
6.3.2
6.3.3
6.3.4
Soap Manufacture
General area
Automatic processes
Control panels
Machines
200-300-500
100-200-300
200-300-500
200-300-500
2
2
1
2
Local lighting may be appropriate
6.4
6.4.1
6.4.2
6.4.3
6.4.4
6.4.5
Paint Works
General
Automatic processes
Control panels
Special batch mixing
Colour matching
200-300-500
150-200-300
200-300-500
500-750-1000
750-1000-1500
2
2
2
2
1
7
MECHANICAL ENGINEERING
7.1
7.1.1
7.1.2
Structural Steel Fabrication
General
Marking off
200-300-500
300-500-750
3
3
Local lighting may be appropriate
7.2
7.2.1
7.2.2
Sheet Metal Works
Pressing, punching, shearing, stamping, spinning,
folding
Benchwork, scribing, inspection
300-500-750
500-750-1000
2
2
7.3
7.3.1
7.3.2
7.3.3
7.3.4
Machine and Tool Shops
Rough bench and machine work
Medium bench and machine work
Fine bench and machine work
Gauge rooms
200-300-500
300-500-750
500-750-1000
750-1000-1500
3
2
2
1
Optical aids may be required
7.4
7.4.1
7.4.2
Die Sinking Shops
General
Fine work
300-500-750
1000-1500-2000
2
1
Flexible local lighting is desirable
7.5
7.5.1
7.5.2
7.5.3
Welding and Soldering Shops
Gas and arc welding, rough spot welding
Medium soldering, brazing, spot welding
Fine soldering, fine spot welding
200-300-500
300-500-750
750-1000-1500
3
3
2
Local lighting is desirable
7.6
7.6.1
7.6.2
7.6.3
Assembly Shops
Rough work for example, frame and heavy
machine assembly
Medium work, for example, engine assembly,
vehicle body assembly
Fine work, for example, office machinery
assembly
200-300-500
300-500-750
500-750-1000
3
2
1
The lighting of vertical surface
may be important
Localized lighting may be useful
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
15
Table 4 — Continued
(l)
(2)
(3)
(4)
(5)
7.6.4 Very fine work, for example, instrument
assembly
7.6.5 Minute work, for example, watch making
7.7 Inspection and Testing Shops
7.7.1 Coarse work, for example, using go/no-go
gauges, inspection of large sub-assemblies
7.7.2 Medium work, for example, inspection of
painted surfaces
7.7.3 Fine work, for example, using calibrated
scales, inspection of precision mechanisms
7.7.4 Very fine work, for example, inspection of
small intricate parts
7.7.5 Minute work, for example, inspection of very
small instruments
7.8 Points Shops and Spray Booths
7.8.1 Dipping, rough spraying
7.8.2 Preparation, ordinary painting, spraying and
finishing
7.8.3 Fine painting, spraying and finishing
7.8.4 Inspection, re-touching and matching
7.9 Plating Shops
7.9.1 Vats and baths
7.9.2 Buffing, polishing burnishing
7.9.3 Final buffing and polishing
7.9.4 Inspection
8 ELECTRICAL AND ELECTRONIC
ENGINEERING
8.1 Electrical Equipment Manufacture
8.1.1 Manufacture of cables and insulated wires,
winding, varnishing and immersion of coils,
assembly of large machines, simple assembly work
8.1.2 Medium assembly, for example, telephones, small
motors
8.1.3 Assembly of precision components, for example,
telecommunication equipment, adjustment,
inspection and calibration
8.1.4 Assembly of high precision parts
8.2 Electronic Equipment Manufacture
8.2.1 Printed circuit board
8.2.1.1 Silk screening
8.2.1.2 Hand insertion of components, soldering
8.2.1.3 Inspection
8.2.1.4 Assembly of wiring harness, cleating harness,
testing and calibration
8.2.1.5 Chassis assembly
8.2.2 Inspection and testing
8.2.2.1 Soak test
8.2.2.2 Safety and functional tests
9 FOOD, DRINK AND TOBACCO
9.1 Slaughter Houses
9.1.1 General
9.1.2 Inspection
9.2 Canning, Preserving and Freezing
9.2,1 Grading and sorting of raw materials
750-1000-1500
1
1000-1500-2000
1
300-500-750
2
500-750-1000
1
750-1000-1500
1
1000-1500-2000
1
2000
1
200-300-500
200-500-750
3
2
500-750-1000
750-1000-1500
2
2
200-300-500
300-500-750
500-750-1000
3
2
2
200-300-500
300-500-750
750-1000-1500
1000-1500-2000
200-300-500
300-500-750
500-750-1000
300-500-750
500-750-1000
750-1000-1500
1
1
1
500-750-1000
1
750-1000-1500
1
150-200-300
200-300-500
2
2
Local lighting and optical aids are
desirable
Local lighting and optical aids are
desirable
Local or localized lighting may be
appropriate
Local or localized lighting may be
appropriate
Local or localized lighting may be
appropriate
Local lighting and optical aids are
desirable
Local lighting and optical aids are
desirable
Special light to reveal fault in the
surface of the material will be
required
Local lighting may be appropriate
Local lighting is desirable. Optical
aids may be useful
Local lighting is desirable. Optical
aids may be useful
Local lighting may be appropriate
Local lighting may be appropriate
A large, low luminance luminaire
overhead ensures specular reflection
conditions which are helpful for
inspection of printed circuits
Local lighting may be appropriated
Local lighting may be appropriated
Lamp of colour rendering group
1A or IB will be required, if
colour judgement is required
16
NATIONAL BUILDING CODE OF INDIA
Table 4 — Continued
(l)
(2)
(3)
(4)
(5)
9.2.2
Preparation
9.2.3
Canned and bottled goods
9.2.3.1
Retorts
9.2.3.2
Automatic processes
9.2.3.3
Labelling and packaging
9.2.4
Frozen foods
9.2.4.1
Process area
9.2.4.2
Packaging and storage
9.3
Bottling, Brewing and Distilling
9.3.1
Keg washing and handling, bottle washing
9.3.2
Keg inspection
9.3.3
Bottle inspection
9.3.4
Process areas
9.3.S
Bottle filling
9.4
Edible Oils and Fats Processing
9.4.1
Refining and blending
9.4.2
Production
9.5
Mills-Milling, Filtering and Packing
9.6
Bakeries
9.6.1
General
9.6.2
Hand decorating, icing
9.7
Chocolate and Confectionery Manufacture
9.7.1
General
9.7.2
Automatic processes
9.7.3
Hand decoration, inspection, wrapping and
packing
9.8
Tobacco Processing
9.8.1
Material preparation, making and packing
9.8.2
Hand processes
10
TEXTILES
10.1
Fibre Preparation
10.1.1
Bale breaking, washing
10.1.2
Stock dyeing, tinting
10.2
Yam Manufacture
10.2.1
Spinning, roving, winding, etc
10.2.2
Healding (drawing in)
10.3
Fabric Production
10.3.1
Knitting
10.3.2
Weaving
10.3.2.1
Jute and hemp
10.3.2.2
Heavy woolens
10.3.2.3
Medium worsteds, fine woolens, cottons
10.3.2.4
Fine worsteds, fine linens, synthetics
10.3.2.5
Mending
10.3.2.6
Inspection
10.4
Fabric Finishing
10.4.1
Dyeing
10.4.2
Calendaring, chemical treatment, etc
10.4.3
Inspection
10.4.3.1
'Grey' cloth
10.4.3.2
Final
10.5
Carpet Manufacture
10.5.1
Winding, beaming
10.5.2
Setting pattern, turfing cropping, trimming,
fringing, latexing and latex drying
10.5.3
Designing, weaving, mending
10.5.4
Inspection
10.5.4.1
General
10.5.4.2
Piece dyeing
300-500-750
3
200-300-500
150-200-300
200-300-500
3
3
3
200-300-500
200-300-500
3
3
150-200-300
200-300-500
3
3
200-300-500
500-750-1000
3
3
200-300-500
300-500-750
3
2
200-300-500
3
200-300-500
300-500-750
2
2
200-300-500
150-200-300
300-500-750
3
3
2
300-500-750
500-750-1000
2
2
200-300-500
200-300-500
300-500-750
750-1000-750
300-500-750
200-300-500
300-500-750
500-750-1000
750-1000-1500
1000-1500-2000
1000-1500-2000
200-300-500
300-500-750
750-1000-1500
1000-1500-2000
200-300-500
300-500-750
500-750-1000
750-1000-1500
500-750-1000
Special lighting will be required
If accurate colour judgements are
required, lamps of colour rendering
group 1 A or IB are used
Local lighting may be appropriate
Local lighting may be appropriate
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
17
Table 4 — Continued
(1)
(2)
(3)
(4)
(5)
11
LEATHER INDUSTRY
ll.l
Leather Manufacture
ll.l.i
Cleaning, tanning and stretching, vats, cutting,
fleshing, stuffing
200-300-500
3
11.1.2
Finishing, scarfing
300-500-750
2
11.2
Leather Working
11.2.1
General
200-300-500
3
11.2.2
Pressing, glazing
300-500-750
2
11.2.3
Cutting, splitting, scarfing, sewing
500-750-1000
■ 2
Directional lighting may be useful.
11.2.4
Grading, matching
2
Local lighting may be appropriate
12
CLOTHING AND FOOTWEAR
12.1
Clothing Manufacture
12.1.1
Preparation of cloth
200-300-500
2
12.1.2
Cutting
500-750-1000
1
12.1.3
Matching
500-750-1000
1
12.1.4
Sewing
750-1000-1500
1
12,1,5
Pressing
300-500-750
2
12.1.6
Inspection
1000-1500-2000
1
Local lighting may be appropriate
12.1.7
Hand tailoring
1000-1500-2000
1
Local lighting may be appropriate
12.2
Hosiery and Knitwear Manufacture
12.2.1
Flat bed knitting machines
300-500-750
2
12.2.2
Circular knitting machines
500-750-1000
2
12.2.3
Lockstitch and overlocking machine
750-1000-1500
1
12.2.4
Linking or running on
750-1000-1500
1
12.2.5
Mending, hand finishing
1000-1500-3000
—
Local lighting may be appropriate
12.2.6
Inspection
1000-1500-2000
2
Local lighting may be appropriate
12.3
Glove Manufacture
12.3.1
Sorting and grading
500-750-1000
1
12.3.2
Pressing, knitting, cutting
300-500-750
2
12.3.3
Sewing
500-750-1000
2
12.3.4
inspection
1000-1500-2000
—
Local lighting may be appropriate
12.4
Hat Manufacture
12.4.1
Stiffening, braiding, refining, forming, sizing,
pounding, ironing
200-300-500
2
12.4.2
Cleaning, flanging, finishing
300-500-750
2
12.4.3
Sewing
500-750=1000
2
12.4.4
Inspection
1000-1500-2000
—
Local lighting may be appropriate
12.5
Boot and Shoe Manufacture
12.5.1
Leather and synthetics
12.5.2
Sotting and grading
750-1000-1500
1
12.5.3
Clicking, closing
750-1000-1500
2
Local or localized lighting may be
appropriate
12.5.4
Preparatory operations
750-1000-1500
2
Local or localized lighting may be
appropriate
12.5.5
Cutting tables and pressure
1000-1500-2000
1
Local or localized lighting may be
appropriate
12.5.6
Bottom stock preparation, lasting, bottoming
finishing, shoe rooms
750-1000-1500
1
Local or localized lighting may be
appropriate
12.5.7
Rubber
12.5.7.1
Washing, compounding, coating, drying,
varnishing, vulcanizing, calendaring, cutting
200-300-500
3
12.5.7.2
Lining, making and finishing
300-500-750
2
13 TIMBER AND FURNITURE
13.1 Sawmills
13.1.1 General
13.1.2 Head saw
13.1.3 Grading
13.2 Woodwork Shops
13.2.1 Rough sawing, bench work
150-200-300
300-500-750
500-750-1000
200-300-500
Localized lighting may be
appropriate
Directional lighting may be useful
18
NATIONAL BUILDING CODE OF INDIA
Table 4 — Continued
(1)
(2)
(3)
(4)
(5)
13.2.2
Sizing, planning, sanding, medium machining and
bftnrh wnrV
300-500-750
2
13.2.3
i^'t'llVll VVU1A
Fine bench and machine work, fine sanding,
finishing
500-750-1000
2
Localized lighting may be
appropriate
13.3
Furniture Manufacture
13.3.1
Raw material stores
50-100-150
3
13.3.2
Finished goods stores
100-150-200
3
13.3.3
Wood matching and assembly, rough sawing,
cutting
200-300-500
2
13.3.4
Machining, sanding and assembly, polishing
300-500-750
2
Localized lighting may be
13.3.5
Tool room
300-500-750
2
appropriate
13.3.6
Spray booths
13.3.6.1
Colour finishing
300-500-750
2
13.3.6.2
Clear finishing
200-300-500
2
13.3.7
Cabinet making
13.3.7.1
Vaneer sorting and grading
750-1000-1500
1
13.3.7.2
Marquetry, pressing, patching and fitting
300-500-750
1
13.3.7.3
Final inspection
500-750-1000
1
Special lighting will be required
13.4
Upholstery Manufacture
13.4.1
13.4.2
Cloth inspection
Filling, covering
1000-1500-2000
300-500-750
1
2
Special lighting will be required
13.4.3
Slipping, cutting, sewing
500-750-1000
2
13.4.4
Mattress making
13.4.5
Assembly
300-500-750
2
13.4.6
Tape edging
750-1000-1500
2
Local lighting may be appropriate
14
PAPER AND PRINTING
14.3
Paper Mills
14.1.1
Pulp mills, preparation plants
200-300-500
3
14.1.2
Paper and board making
14.1.2.1
General
200-300-500
3
14.1.2.2
Automatic process
150-200-300
3
Supplementary lighting may be
14.1.2.3
Inspection, sorting
300-500-750
1
necessary for maintenance work
14.1.3
Paper converting processes
14.1.3.1
General
200-300-500
3
14.1.3.2
Associated printing
300-500-750
2
14.2
Printing Works -
14.2.1
Type foundries
14.2.1.1
Matrix making, dressing type, hand and machine
coating
200-300-500
3
14.2.1.2
Front assembly, sorting
500-750-1000
2
14.2.2
Composing rooms
14.2.2.1
Hand composing, imposition and distribution
500-750-1000
1
14.2.2.2
Hot metal keyboard
500-750-1000
1
14.2.2.3
Hot metal casting
200-300-500
2
14.2.2.4
Photo composing keyboard or setters
300-500-750
1
14.2.2.5
Paste up
500-750-1000
1
14.2.2.6
14.2.2.7
Illuminated tables — general lighting
Proof presses
200-300-500
300-500-750
2
Dimming may be required
14.2.2.8
Proof reading
500-750-1000
1
14.2.3
Graphic reproduction
14.2.3.1
General
300-500-750
2
14.2.3.2
14.2.3.3
Precision proofing, retouching, etching
Colour reproduction and inspection
750-1000-1500
750-1000-1500
1
1
Local lighting may be appropriate
14.2.4
Printing machine room
14.2.4.1
Presses
300-500-750
2
14.2.4.2
Premake ready
300-500-750
2
14.2.4.3
Printed sheet inspection
750-1000-1500
1
14.2.5
Binding
14.2.5.1
Folding, pasting, punching and stitching
300-500-750
2
14.2.5.2
Cutting, assembling, embossing
500-750-1000
2
15
PLASTIC AND RUBBER
15.1
Plastic Products
15.1.1
Automatic plant
PART 8 BUILDING SERVICES -SECTION 1 LIGHTING AND VENTILATION
19
Table 4 — Continued
(l)
(2)
(3)
(4)
(5)
15.1.1.1 Without manual control
15.1.1.2 With occasional manual control
15.1.1.3 With continuous manual control
15.1.1.4 Control rooms
15.1.1.5 Control platforms
15.1.2 Non-automatic plant
15.1.2.1 Mixing, calendaring, extrusion, injection,
compression and blow moulding, sheet fabrication
15.1.2.2 Trimming, cutting, polishing, cementing
15.1.2.3 Printing, inspection
15.2 Rubber Products
15.2.1 Stock preparation — plasticizing, milling
15.2.2 Calendaring, fabric preparation, stock-cutting
15.2.3 Extruding, moulding
15.2.4 Inspection
16 DISTRIBUTION AND STORAGE
16.1 Work Stores
16.1.1 Unpacking, sorting
16.1.2 Large item storage
16.1.3 Small item rack storage
16.1.4 Issue counter, records, storeman's desk
16.2 Warehouses and Bulk Stores
16.2.1 Storage of goods where indentification requires
only limited preparation of detail
16.2.2 Storage of goods where identification requires
perception of detail
16.2.3
Automatic high bay rack stores
16.2.3.1
Gangway
16.2.3.2
Control station
16.2.3.3
Packing and dispatch
16.2.3.4
Loading bays
16.3
Cold Stores
16.3.1
General
16.3.2
Breakdown, make-up and dispatch
16.3.3
Loading bays
17
COMMERCE
17.1
Offices
17.1.1
General offices
17.1.2
Deep plan general offices
17.1.3
Computer work stations
17.1.4
Conference rooms, executive offices
17.1.5
Computer and data preparation rooms
171.6
Filing rooms
17.2
Drawing Offices
17.2.1
General
17.2.2
Drawing boards
17.2.3
Computer aided design and drafting
17.2.4
Print rooms
17.3
Banks and Building Societies
17.3.1
Counter, office area
17.3.2
Public area
18
SERVICES
18.1
Garages
18.1.1
Interior parking areas
30-50-100
50-100-150
200-300-500
200-300-500
200-300-500
3
3
3
1
2
200-300-500
3
300-500-750
750-1000-1500
2
1
150-200-300
300-500-750
300-500-750
750-1000-1500
3
3
2
100-150-200
3
150-200-300
3
50-100-150
3
200-300-500
3
300-500-750
2
50-100-150
3
100-150-200
3
20
150-200-300
200-300-500
100-150-200
3
3
3
200-300-500
200-300-500
100-150-200
3
3
3
300-500-750
500-750-1000
300-500-750
300-500-750
300-500-750
200-300-500
300-500-750
500-750-1000
200-300-500
300-500-750
200-300-500
20-30-50
Local lighting may be appropriate
Avoid glare to drivers of vehicles
approaching the loading bay
Avoid glare to drivers of vehicles
approaching the loading bay
Avoid glare to drivers of vehicles
approaching the loading bay
Avoid glare to drivers of vehicles
approaching the loading bay
Local or localized lighting may be
appropriate
Avoid glare to drivers of vehicles
approaching the loading bay
Avoid glare to drivers of vehicles
approaching the loading bay
Special lighting is required
20
NATIONAL BUILDING CODE OF INDIA
Table 4 — Continued
(i)
(2)
(3)
(4)
(5)
18.1.2
18.1.3
General repairs, servicing, washing, polishing
Workbench
18.1.4 Spray booths
18.1.5 External apron
18.1.5.1 General
18.1.5.2 Pump area (retail sales)
18.2
18.2.1
18.2.1.1
18.2.1.2
Appliance servicing
Workshop
General
Workbench
18.2.1.3 Counter
18.2.1.4 Stores
18.3 Laundries
18.3.1 Commercial laundries
18.3.2 Receiving, sorting, washing, drying, ironing,
despatch, dry-cleaning, bulk machine work
18.3.3 Head ironing, pressing, mending, spotting,
inspection
18.3.4 Launderettes
18.4 Sewage Treatment Works
18.4.1 Walkways
18.4.2 Process areas
19 RETAILING
19.1 Small Shops with Counters
19.2 Small Self-Service Shops with Island Displays
19.3 Supper Markets, Hyper-Markets
19.3.1 General
19.3.2 Checkout
19.3.3 Showroom for large objects, for example, cars,
furnitures
19.3.4 Shopping precincts and arcades
20 PLACES OF PUBLIC ASSEMBLY
20.1 Public Rooms, Village Halls, Worship Halls
20.2 Concert Halls, Cinemas and Theatres
20.2.1 Foyer
20.2.2 Booking office
20.2.3 Auditorium
20.2.4 Dressing rooms
20.2.5 Projection room
20.3
Churches
20.3.1
Body of church
20.3.2
Pulpit, lectern
20.3.3
Choir stalls
20.3.4
Alter, communion table, chancel
20.3.5
Vestries
20.3.6
Organ
20.4
Hospitals
20.4.1
Anaesthatic rooms
200-300-500
300-500-750
300-500-750
30-50-100
200-300-500
200-300-500
300-500-750
200-300-500
200-300-500
200-300-500
300-500-750
200-300-500
30-50-100
50-100-150
300-500-750
300-500-750
300-500-750
300-500-750
300-500-750
100-150-200
200-300-500
150-200-300
200-300-500
50-100-150
200-300=500
100-150-200
100-150-200
200-300-500
200-300-500
100-150-200
100-150-200
200-300-500
Local or localized lighting may
be appropriate
Care should be taken to avoid
glare to drivers and neighbouring
residents
See 'Retailing'
Localized lighting may be
appropriate
Localized lighting may be
appropriate
The service illuminance should be
provided on the horizontal plane of
the counter. Where wall displays
are used, a similar illuminance on
the walls is desirable
Local or localized lighting may
be appropriate
Dimming facilities will be
necessary. Special lighting of
the aisles is desirable
Special mirror lighting for
make-up may be required
Use local lighting
Local lighting may be appropriate
Additional lighting to provide
emphasis is desirable
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
21
Table 4 — Continued
(l)
(2)
(3)
(4)
(5)
20.4.1.1
General
20.4.1.2
Local
20.4.2
Consulting areas
20.4.2.1
General
20.4.2.2
Examination
20.4.3
Corridors
20.4.3.1
General
20.4.4
Ward corridors
20.4.4.1
Day, screened from bays
20.4.4.2
Day, open to natural light
20.4.4.3
Moming/Evening
20.4.4.4
Night
20.4.5
Cubicles
20.4.5.1
General
20.4.5.2
Treatment
20.4.6
Examination
20.4.6.1
General
20.4.6.2
Local inspection
20.4.7
Intensive therapy
20.4.7.1
Bad head
20.4.7.2
Circulation between bed ends
20.4.7.3
Observation
20.4.7.4
Local observation
20.4.7.5
Staff base (day)
20.4.7.6
Staff base (night)
20.4.8
Laboratories
20.4.8.1
General
20.4.8.2
Examination
20.4.9
Nurses' stations
20.4.9.1
Morning/day /evening
20.4.9.2
Night desks
20.4.9.3
Night, medical trolleys
20.4.10
Operating theatres
20.4.10.1
General
20.4.10.2
Local
20.4.11
Pathology departments
20.4.11.1
General
20.4.11.2
Examination
20.4.11.3
Pharmacies
20.4.11.4
Reception/enquiry
20.4.11.5
Recovery rooms
20.4.12
Ward -circulation
20.4.12.1
Day
20.4.12.2
Morning/Evening
20.4.12.3
Night
20.4.13
Ward-bed head
20.4.13.1
Morning/Evening
20.4.13.2
Reading
20.4.14
Night
20.4.14.1
Adult
20.4.14.2
Pediatric
20.4.14.3
Psychiatric
20.4.14.4
Watch
20.4.15
X-Ray areas
20.4.15.1
General
20.4.15.2
Diagnostic
20.4.15.3
Operative
20.4.15.4
Process dark room
20.4.16
Surgeries
20.4.16.1
General
20.4.16.2
Waiting rooms
20.4.17
Dental surgeries
20.4.17.1
Chair
200-300-500
750-1000-1500
200-300-500
750-1000-1500
100-150-200
150-200-300
150-200-300
(total)
100-150-200
5-10
200-300-500
750-1000-1500
200-300-500
750-1000-1500
30-50
50-100450
200-300-500
750-1000-1500
200-300-500
30
200-300-500
300-500-750
200-300-500
30
50-100-150
300-500-750
10 000 to 50 000
200-300-500
300-500-750
200-300-500
200-300-500
200-300-500
50-100-150
50-100-150
3-5
30-50
100-150-200
0.1-1
1
1-5
5
150-200-300
150-200-300
200-300-500
50
200-300-500
100-150-200
Special lighting
Special operating lights are used
22
NATIONAL BUILDING CODE OF INDIA
Table 4 — Continued
(l)
(2)
(3)
(4)
(5)
20.4.17.2
Laboratories
300-500-750
20.4.18
Consulting rooms
20.4.18.1
General
200-300-500
20.4.18.2
Desk
300-500-750
20.4.18.3
Examination couch
300-500-750
20.4.18.4
Ophthalmic wall and near-vision charts
300-500-750
20.5
Hotels
20.5.1
Entrance halls
50-100-150
20.5.2
Reception, cashier's and porters' desks
200-300-500
20.5.3 Bars, coffee base, dining rooms, grill rooms,
restaurants, lounges
20.5.4 Cloak rooms, baggage rooms
20.5.5 Bed rooms
20.5.6 Bathroom
20.5.7 Food preparation and stores, cellars, lifts and
corridors
20.6 Libraries
20.6.1 Lending library
20.6.1.1 General
20.6.1.2 Counters
20.6.1.3 Bookshelves
20.6.1.4
Reading rooms
20.6.1,5
Reading tables
20.6.2
Catalogues
20.6.2.1
Card
20.6.2.2
Microfiche /Visual display units
20.6.3
Reference libraries
20.6.3.1
General
20.6.3.2
Counters
20.6.3.3 Bookshelves
20.6.3.4 Study tables, carrels
20.6.3.5 Map room
20.6.4 Display and exhibition areas
20.6.4.1 Exhibits insensitive to light
20.6.4.2 Exhibit sensitive to light, for example, pictures,
prints, rare books in archives
20.6.5 Library workrooms
20.6.5.1 Book repair and binding
20.6.5.2 Catalogue and sorting
20.6.5.3 Remote book stores
20.7 Museums and Art Galleries
20.7.1 Exhibits insensitive to light
20.7.2 Light sensitive exhibits, for example, oil and
temper paints, undyed leather, bone, ivory, wood,
etc
20.7.3 Extremely light sensitive exhibits, for example,
textiles, water colours, prints and drawings, skins,
botanical specimens, etc
20.7.4 Conservation studies and workshops
20.8 Sports Facilities
50-200
50-100-150
30-50-100
50-100-150
50
300-500-750
Localized lighting may be
appropriate
The lighting should be designed to
create an appropriate atmosphere
Supplementary local lighting at
the bed head, writing table should
be provided
Supplementary local lighting near
the mirror is desirable
See 'General Building Areas*
200-300-500
1
300-500-750
1
Localized lighting may be
appropriate
100-150-200
2
The service illuminance should be
provided on the vertical face at
the bottom of the bookstack
200-300-500
1
200-300-500
1
Localized lighting may be
appropriate
100-150-200
2
100-150-200
2
200-300-500
1
300-500-750
1
Localized lighting may be
appropriate
100-150-200
2
The service illuminance should
be provided on a vertical surface
at the foot of the bookshelves
300-500-750
1
200-300-500
1
200-300-500
50 to 150
—
300-500-750
2
300-500-750
2
100-150-200
3
200-300-500
150
—
This is a maximum illuminance to
be provided on the principal plane
of the exhibit
This is the maximum illuminance
to be provided on the principal
plane of the object
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
23
Table 4 — Continued
(1)
(2)
(3)
(4)
(5)
Multi-purpose sports halls
300-750
21
EDUCATION
21.1 Assembly Halls
21.1.1 General
21.1.2 Platform and stage
22.2.9 Platforms (covered)
22.2.10 Platforms (open)
200-300-500
21.2
Teaching Spaces
General
200-300-500
21.3
Lecture Theatres
21.3.1
General
200-300-500
21.3.2
Demonstration benches
300-500-750
21.4
Seminar Rooms
300-500-750
21.5
Art Rooms
300-500-750
21.6
Needlework Rooms
300-500-750
21.7
Laboratories
300-500-750
21.8
Libraries
200-300-500
21.9
Music Rooms
200-300-500
21.10
Sports Halls
200-300-500
21.11
Workshops
200-300-500
22
TRANSPORT
22.1
Airports
22.1.1
Ticket counters, checking desks, and information
desks
300-500-750
22.1.2
Departure lounges, other waiting areas
150-200-300
22.1.3
Baggage reclaim
150-200-300
22.1.4
Baggage handling
50-100-150
22.1.5
Customs and immigration halls
300-500-750
22.1.6
Concourse
150-200-300
22.2
Railway Stations
22.2.1
Ticket office
300-500-750
22.2.2
Information office
300-500-750
22.2.3
Parcels office, left
22.2.4
Luggage office
22.2.4.1
General
50-100-150
22.2.4.2
Counter
150-200-300
22.2.5
Waiting rooms
150-200-300
22.2.6
Concourse
150-200-300
22.2.7
Time table
150-200-300
22.2.8
Ticket barriers
150-200-300
30-50-100
20
This lighting system should be
sufficiently flexible to provide
lighting suitable for the variety of
sports and activities that take place
in sports halls. Higher illuminance
of 1000-2000 lux would be
required for television coverage
Special lighting to provide
emphasis and to facilitate the use
of the platform/ stage is desirable
Localized lighting may be
appropriate
Localized lighting may be
appropriate
Localized lighting may be
appropriate
Localized lighting over the
counter may be appropriate
Localized lighting may be
appropriate
Localized lighting may be
appropriate
Care should be taken to light and
mark the edge of the platform
clearly
Care should be taken to light and
mark the edge of the platform
clearly
22.3
Coach Stations
24
NATIONAL BUILDING CODE OF INDIA
Table 4 — Concluded
(D
(2)
(3)
(4)
(5)
22.3.1 Ticket offices
22.3.2
Information offices
23.7.1.4 Control rooms
23.7.1.5 Mechanical plant room
23.7.1.6 Electrical power supply and distribution rooms
23.7.1.7 Store rooms
23.8
Car Parks
23.8.1
Covered car parks
23.8.1.1
Floors
23.8.1.2
Ramps and corners
23.8.1.3
Enterances and exits
23.8.1.4
Control booths
23.8.1.5
Outdoor car parks
300-500-750
300-500-750
22.3.3
Left luggage office
22.3.3.1
General
50-100-150
22.3.3.2
Counter
150-200-300
22,3,4
Waiting rooms
150-200-300
22.3.5
Concourse
150-200-300
22.3.6
Time tables
150-200-300
22.3.7
Loading areas
100-150-200
23
GENERAL BUILDING AREAS
23.1
Entrance
23.1.1
Entrance halls, lobbies, waiting rooms
150-200-300
23.1.2
Enquiry desks
300-500-750
23.1.3
Gatehouses
150-200-300
23.2
Circulation Areas
23.2.1
Lifts
50-100-150
23.2.2
Corridors, passageways, stairs
50-100-150
23.2.3
Escalators, travellators
100-150-200
23.3
Medical and First Aid Centres
23.3.1
Consulting rooms, treatment rooms
300-500-750
23.3.2
Rest rooms
100-150-200
23.3.3
Medical stores
100-150-200
23.4
Staff Rooms
23.4.1
Changing, locker and cleaners rooms, cloakrooms,
lavatories
50-100-150
23.4.2
Rest rooms
100-150-200
23.5
Staff Restaurants
23.5.1
Canteens, cafeterias, dining rooms, mess rooms
150-200-300
23.5.2
Servery, vegetable preparation, washing-up area
200-300-500
23.5.3
Food preparation and cooking
300-500-750
23.5.4
Food stores, cellars
100-150-200
23.6
Communications
23.6.1
Switchboard rooms
200-300-500
23.6.2
Telephone apparatus rooms
100-150-200
23.6.3
Telex room, post room
300-500-750
23.6.4
Reprographic room
200-300-500
23.7
Building Services
23.7.1
Boiler houses
23.7.1.1
General
50-100-150
23.7.1.2
Boiler front
100-150-200
23.7.1.3
Boiler control room
200-300-500
200-300-500
100-150-200
100-150-200
50-100-150
5-20
30
50-100-150
150-200-300
5-20
Localized lighting over the
counter may be appropriate
Localized lighting over the
counter may be appropriate
Localized lighting is appropriate
Local lighting is appropriate
Localized lighting may be
appropriate
Localized lighting of the control
display and the control desk may
be appropriate
Localized lighting of the control
display and the control desk may
be appropriate
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
25
It is important, when lighting stairways, to prevent
disability from glare caused by direct sight of bright
sources to emphasize the edges of the treads and to
avoid confusing shadows. The same precautions should
be taken in the lighting of cat-walks and stairways on
outdoor industrial plants.
4,1,5*2 Entrances
The problems of correctly grading the lighting within
a building to allow adequate time for adaptation when
passing from one area to another area are particularly
acute at building entrances. These are given below:
a) By day, people entering a building will be
adapted to the very high levels of brightness
usually present outdoors and there is risk of
accident if entrance areas, particularly any
steps, are poorly lighted. This problem may
often be overcome by arranging windows
to give adequate natural lighting at the
immediate entrance, grading to lower levels
further inside the entrance area. Where this
cannot be done, supplementary artificial
lighting should be installed to raise the level
of illumination to an appropriate value.
b) At night it is desirable to light entrance halls
and lobbies so that the illumination level
reduces towards the exit and so that no bright
fittings are in the line of sight of people
leaving the building. Any entrance steps to
the building should be well-lighted by
correctly screened fittings.
i 1 i\ Fnr Hf frail p H infnrrrmfrirm r^ onrHincr r»rinr*ir»lfc nf
crnnrl liahHncr rpfprpnrf* mav hp maHp tr\ annti nrapHpp
rs-K?vi
4.2 Daylighting
TK^k nrimin; CAiir/ia r\£ lin-Vitinrr £r\r rlo^flirrlil-inrr tc trua
111U UlllllUljr OV^UIWW V^-L 11 gill Hlg 1U1 V-lt4.Jllglllll.lg, LJ 111V
cun T 1 !-!^ It rrhf rt*nt*i\n*r\ Y\\r tliA ^orfrh f*-r*m tliA cun
iiuii. niv iigni. x \s\s\si » vu yj j inv \^t*i vn iium niv ouii
rrmeicte r\£ t\irr\ ncirfc namp»K/ Atre^nt crJar illiiminanr'A
VV/IIUIUIU Wl I- " \S fJ\*M. tO , 11U1 J.XX/X J , UJ.X **/** V LIV1UI iii U111111U11VW
anrl cVv illnminnnr'p P?r\r frhp nurnncpc r\f rtavlioliTino
desi°n direct solar illuminance shall not be
considered and onW skv illuminance shall be taken
as contributing to illumination of the building interiors
during the dav
4.2.1 The relative amount of sky illuminance depends
on the position of the sun defined by its altitude, which
in turn, varies with the latitude of the locality, the day
of the year and the time of the day, as indicated in
Table 5.
4.2.2 The external available horizontal sky illuminance
(diffuse illuminance) values which are exceeded for
about 90 percent of the daytime working hours may
be taken as outdoor design illuminance values for
ensuring adequacy of day lighting design. The outdoor
design sky illuminance varies for different climatic
regions of the country. The recommended design sky
illuminance values are 6 800 lux for cold climate,
8 000 lux for composite climate, 9 000 lux for warm
humid climate, 9 000 lux for temperate climate and
10 500 for hot-dry climate. For integration with the
artificial lighting during daytime working hours an
increase of 500 lux in the recommended sky design
illuminance for daylighting is suggested.
4*2^3 The daylight factor is dependent on the sky
luminance distribution, which varies with atmospheric
conditions. A clear design sky with its non-uniform
distribution of luminance is adopted for the purposes
of design in this section.
Table 5 Solar- Altitudes (to the Nearest Degree) for Indian Latitudes
(Clause 4.2.1)
Period of
22 June
21 March and 23 September
22 December
i ear
**~ '"
-^
***"
~"N
f
"*N
nuurs ui
u/ uu
uo uu
\jy uu
1U uu
11 uu
1Z, uu
u/ uu
uo uu
uv uu
1UUU
11 uu
LZUU
u/ uu
uouu
uy uu
1UUU
11 uu
1Z, uu
Dav (Sun
or Solar)
Latitude
17 00
(2)
16 00
(3)
15 00
(4)
1400
(5)
13 00
(6)
(7)
17 00
(8)
16 00
(9)
15 00
(10)
14 00
(11)
13 00
(12)
(13)
17 00
16 00
15 00
14 00
1300
_
0)
(14)
(15)
(16)
(17)
(118)
(19)
1G°N
18
31
4*
in
nn
1 *
A A
72
on
n
J7
IS.
AfL
1 lOXT
1J n
1 n
1^»
46
uu
/z,
CiC\
ou
15
A A
CCi
JO
l\J
O
O
^ 1
A^
HO
C 1
C A
I6°N
20
33
47
6i
74
S3
14
29
43
56
68
74
7
19
31
41
48
51
I9 G N
21
34
48
62
75
86
14
28
42
55
66
71
5
18
29
48
45
48
22°N
22
35
49
62
75
89
14
28
41
53
64
68
4
16
27
36
42
45
25°N
23
36
49
63
*
76
88
13
27
40
52
61
65
3
14
25
34
39
42
28°N
23
36
49
63
76
86
13
26
39
50
59
62
1
13
23
31
37
39
31°N
24
37
50
62
75
82
13
25
37
48
56
56
—
11
21
28
34
36
34°N
25
37
49
62
73
79
12
25
36
46
53
56
—
9
18
26
31
33
INAI1UINAL BUILDIINli tUUK U* IINU1A
4.2.4 Components of Daylight Factor
Daylight factor is the sum of all the daylight reaching
on an indoor reference point from the following
sources:
a) The direct sky visible from the point,
b) External surfaces reflecting light directly (see
Note 1) to the point, and
c) Internal surfaces reflecting and inter-
reflecting light to the point.
NOTES
1 External surface reflection may be computed
approximately only for points at the centre of the room,
and for detailed analysis procedures are complicated
and these may be ignored for actual calculations.
2 Each of the three components, when expressed as a
ratio or percent of the simultaneous external illuminance
on the horizontal plane, defines respectively the sky
component (SC), the external reflected component
(ERC) and the internal reflected component (IRC) of
the daylight factor.
4.2.4.1 The daylight factors on the horizontal plane
only are usually taken, as the working plane in a room
is generally horizontal; however, the factors in vertical
planes should also be considered when specifying
daylighting values for special cases, such as daylighting
on class-rooms, blackboards, pictures and paintings
hung on walls.
4.2.5 Sky Component (SC)
Sky component for a window of any size is computed
by the use of the appropriate table of Annex A.
a) The recommended sky component level
should be ensured generally on the working
plane at the following positions:
1) at a distance of 3 m to 3.75 m from
the window along the central line
perpendicular to the window,
2) at the centre of the room if more
appropriate, and
3) at fixed locations, such as school desks,
black-boards and office tables.
b) The daylight area of the prescribed sky
component should not normally be less than
half the total area of the room.
4.2.5.1 The values obtainable from the tables are for
rectangular, open unglazed windows, with no external
obstructions. The values shall be corrected for the
presence of window bars, glazing and external
obstructions, if any. This assumes the maintenance of
a regular cleaning schedule.
4.2.5.2 Corrections for window bars
The corrections for window bars shall be made by
multiplying the values read from tables in Annex A
by a factor equal to the ratio of the clear opening to the
overall opening.
4.2.5.3 Correction for glazing
Where windows are glazed, the sky components
obtained from Annex A shall be reduced by 10 to 20
percent, provided the panes are of clear and clean glass.
Where glass is of the frosted (ground) type, the sky
components read from Annex A may be reduced by
15 to 30 percent. In case of tinted or reflective glass
the reduction is about 50 percent. Higher indicated
correction corresponds to larger windows and/or near
reference points. In the case of openings and glazings
which are not vertical, suitable correction shall be taken
into account.
4.2.5.4 Correction for external obstructions
There is no separate correction, except that the values
from tables in Annex A shall be read only for the
unobstructed portions of the window.
4.2.6 External Reflected Component (ERC)
The value of the sky component corresponding to the
portion of the window obstructed by the external
obstructions may be found by the use of methods
described in Annex B of good practice [8-1(3)].
These values when multiplied by the correction factors,
corresponding to the mean elevation of obstruction
from the point in question as given in Table 6, can be
taken as the external reflected components for that
point.
Table 6 Correction Factor for ERC
(Clause 4.2.6)
Mean Angle of Elevation
Correction Factor
(1)
(2)
5°
0.086
15°
0.086
25°
0.142
35°
0.192
45°
0.226
55°
0.274
65°
0.304
75°
0.324
85° /
0.334
4.2.6.1 For method of calculating ERC, reference may
be made to accepted standard (see Examples 10 and
1 1 given in Annex B of good practice [8-1(3)].
4.2.7 Internal Reflected Component (IRC)
The component of daylight factor contributed by
reflection from the inside surfaces varies directly as
the window area and inversely as the total area of
internal surfaces, and depends on the reflection factor
of the floor, wall and roof surfaces inside and of the
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
27
ground outside. For rooms white-washed on walls and
ceiling and windows of normal sizes, the IRC will have
sizeable value even at points far away from the
window. External obstructions, when present, will
proportionately reduce IRC. Where accurate values of
IRC are desired, the same may be done in accordance
with the good practice [8-1(3)].
4.2.8 General Principles of Openings to Afford Good
Lighting
4.2.8.1 Generally, while taller openings give greater
penetrations, broader openings give better distribution
of light. It is preferable that some area of the sky at
an altitude of 20° to 25° should light up the working
plane.
4.2.8.2 Broader openings may also be equally or more
efficient, provided their sills are raised by 300 mm to
600 mm above the working plane.
NOTE — It is to be noted that while placing window with a
high sill level might help natural lighting, this is likely to reduce
ventilation at work levels. While designing the opening for
ventilation also, a compromise may be made by providing the
sill level about 150 mm below the head level of workers.
4.2.8.3 For a given penetration, a number of small
openings properly positioned along the same, adjacent
or opposite walls will give better distribution of
illumination than a single large opening. The sky
component at any point, due to a number of openings
may be easily determined from the corresponding sky
component contour charts appropriately superposed.
The sum of the individual sky component for each
opening at the point gives the overall component due
to all the openings. The same charts may also facilitate
easy drawing of sky component contours due to
multiple openings.
4.2.8.4 Unilateral lighting from side openings will, in
general, be unsatisfactory if the effective width of the
room is more than 2 to 2.5 times the distance from the
floor to the top of the opening. In such cases provision
of light shelves is always advantageous.
4.2.8.5 Openings on two opposite sides will give
greater uniformity of internal daylight illumination,
especially when the room is 7 m or more across. They
also minimize glare by illuminating the wall surrounding
each of the opposing openings. Side openings on one
side and clerestory openings on the opposite side may
be provided where the situation so requires.
4.2.8.6 Cross-lighting with openings on adjacent walls
tends to increase the diffused lighting within a room.
4.2.8.7 Openings in deep reveals tend to minimize
glare effects.
4.2.8.8 Openings shall be provided with CHAJJAHS,
louvers, baffles or other shading devices to exclude,
as far as possible, direct sunlight entering the room.
CHAJJAHS, louvers, etc, reduce the effective height
of the opening for which due allowance shall be made.
Broad and low openings are, in general, much easier
to shade against sunlight entry. Direct sunlight, when
it enters, increases the inside illuminance very
considerably. Glare will result if it falls on walls at
low angles, more so than when it falls on floors,
especially when the floors are dark coloured or less
reflective.
4.2.8.9 Light control media, such as translucent glass
panes (opal or matt) surfaced by grinding, etching or
sandblasting, configurated or corrugated glass, certain
types of prismatic glass, tinted glass and glass blasts
are often used. They should be provided, either fixed
or movable outside or inside, especially in the upper
portions of the openings. The lower portions are usually
left clear to afford desirable view. The chief purpose
of such fixtures is to reflect part of the light on to the
roof and thereby increase the diffuse lighting within,
light up the farther areas in the room and thereby
produce a more uniform illumination throughout. They
will also prevent the opening causing serious glare
discomfort to the occupants but will provide some glare
when illuminated by direct sunlight.
4.2.9 Availability of Daylight in Multi-storeyedrBlock
Proper planning and layout of building can add
appreciably to daylighting illumination inside. Certain
dispositions of building masses offer much less mutual
obstruction to daylight than others and have a
significant relevance, especially when intensive site
planning is undertaken. The relative availability of
daylight in multi-storeyed blocks of different relative
orientations are given in Table 7.
Table 7 Relative Availability of Daylight on the
Window Plane at Ground Level in a Four-
Storeyed Building Blocks (Clear Design-Sky as
Basis, Daylight Availability Taken as Unity on
an Unobstructed Facade, Values are for
the Centre of the Blocks)
{Clause 4.2.9)
Distance of Infinitely Parallel Blocks Parallel Blocks
Separation Long Facing Each Facing Gaps
Between Parallel Other Between Opposite
Blocks Blocks (Length * Blocks (Length =
2 x Height) 2 x Height)
(1) (2) (3) (4)
0.5 Ht
0.15
0J5 ,
0.25
l.OHt
0.30
032
0.38
1.5 Ht
0.40
050
0.55
2.0 Ht
0.50
0.60
0.68
4.2.10 For specified requirements for daylighting of
special occupancies and areas, reference may be made
to good practice [8-1(4)].
28
NATIONAL BUILDING CODE OF INDIA
4.3 Artificial Lighting
4.3.1 Artificial lighting may have to be provided
a) where the recommended illumination levels
have to be obtained by artificial lighting only,
b) to supplement daylighting when the level of
illumination falls below the recommended
value, and
c) where visual task may demand a higher level
of illumination.
4.3.2 Artificial Lighting Design for Interiors
For general lighting purposes, the recommended
practice is to design for a level of illumination on the
working plane on the basis of the recommended levels
for visual tasks given in Table 4 by a method called
'Lumen method'. In order to make the necessary
detailed calculations concerning the type and quantity
of lighting equipment necessary, advance information
on the surface reflectances of walls, ceilings and floors
is required. Similarly, calculations concerning the
brightness ratio in the interior call for details of the
interior decor and furnishing. Stepwise guidance
regarding designing the interior lighting systems for a
building using the 'Lumen method' is given in 4.3.2.1
to 4.3.2.4.
4.3.2.1 Determination of the illumination level
Recommended value of illumination shall be taken
from Table 4, depending upon the type of work to be
carried out in the location in question and the visual
tasks involved.
4.3.2.2 Selection of the light sources and luminaires
The selection of light sources and luminaires depends
on the choice of lighting system, namely, general
lighting, directional lighting and localized or local
lighting.
4.3.2.3 Determination of the luminous flux
a) The luminous flux (# ) reaching the working
plane depends upon the following:
1) lumen output of the lamps,
2) type of luminaire,
3) proportion of the room (room index) (fc ),
4) reflectance of internal surfaces of the
room,
5) depreciation in the lumen output of the
lamps after burning their rated life, and
6) depreciation due to dirt collection on
luminaires and room suface.
b) Coefficient of Utilization or Utilization Factor
1) The compilation of tables for the
utilization factor requires a considerable
amount of calculations, especially if these
tables have to cover a wide range of
lighting practices. For every luminaire,
the exact light distribution has to be
measured in the laboratory and their
efficiencies have to be calculated and
measured exactly. These measurements
comprise:
i) the luminous flux radiated by the
luminaires directly to the measuring
surface,
ii) the luminous flux reflected and re-
reflected by the ceiling and the walls
to the measuring surface, and
iii) the inter-reflections between the
ceiling and wall which result in
the measuring surface receiving
additional luminous flux.
All these measurements have to be made for
different reflection factors of the ceiling and
the walls for all necessary room indices. These
tables have also to indicate the maintenance
factor to be taken for the luminous flux
depreciation throughout the life of an
installation due to ageing of the lamp and
owing to the deposition of dirt on the lamps
and luminaires and room surfaces.
2) The values of the reflection factor of the
ceiling and of the wall are as follows:
White and very light colours 0.7
Light colours 0.5
Middle tints 0.3
Dark colours 0.1
For the walls, taking into account the
influence of the windows without curtains,
shelves, almirahs and doors with different
colours, etc, should be estimated.
c) Calculation for determining the luminous
flux
E =B±
av A
E A
or, = av for new condition
E A
and = av , for working condition
jid
where
= Total luminous flux of the light sources
installed in the room inlumens;
E v = Average illumination level required on the
working plane inlux;
A = Area of the working plane in m 2 ;
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
29
H - the utilization factor in new conditions; and
d — maintenance factor.
In practice, it is easier to calculate straightaway the
number of lamps or luminaires from:
N y
EA
N^
lamp Vd^
E av A
V d <k™™
where
lamp
K
lamp
N t
= Luminous flux of each lamp in lumens,
= Luminous flux of each luminaire in
lumens,
= Total number of lamps, and
= Total number of luminaires.
luminaires
4.3.2.4 Arrangement of the luminaires
This is done to achieve better uniformly distributed
illumination. The location of the luminaires has an
important effect on the utilization factor.
a) In general, luminaires are spaced 'a' metre
apart in either direction, while the distance of
the end luminaire from the wall is 'V2 a metre.
The distance 'a' is more or less equal to the
mounting height 7/ ' between the luminaire
and the working plane. The utilization factor
tables are calculated for this arrangement of
luminaires.
b) For small rooms where the room index (k) is
less than 1, the distance 'a' should always be
less than H , since otherwise luminaires
nr
cannot be properly located. In most cases of
such rooms, four or two luminaires are placed
for good general lighting. If, however, in such
rooms only one luminaire is installed in the
middle, higher utilization factors are obtained,
but the uniformity of distribution is poor. For
such cases, references should be made to the
additional tables for k - 0.6 to 1.25 for
r
luminaires located centrally.
4.3.3 Artificial Lighting to Supplement Daylighting
4.3.3.1 The need for general supplementary artificial
lighting arises due to diminution of daylighting beyond
design hours, that is, for solar altitude below 15° or
when dark cloudy conditions occur.
4.3.3.2 The need may also arise for providing artificial
lighting during the day in the innermost parts of the
building which cannot be adequately provided with
daylighting, or when the outside windows are not of
adequate size or when there are unavoidable external
obstructions to the incoming daylighting.
4.3.3.3 The need for supplementary lighting during
the day arises, particularly when the daylighting on
the working plane falls below 100 lux and the
surrounding luminance drops below 19 cd/m 2 .
4.3.3.4 The requirement of supplementary artificial
lighting increases with the decrease in daylighting
availability. Therefore, conditions near sunset or
sunrise or equivalent conditions due to clouds or
obstructions, etc, represent the worst conditions when
the supplementary lighting is most needed.
4.3.3.5 The requirement of supplementary artificial
lighting when daylighting availability becomes poor
may be determined from Fig. 3 for an assumed ceiling
height of 3.0 m, depending upon floor area, fenestration
percentage and room surface reflectance. Cool daylight
fluorescent tubes are recommended with semi-direct
luminaires. To ensure a good distribution of
illumination, the mounting height should be between
1 .5 m and 2.0 m above the work plane for a separation
of 2.0 m to 3.0 m between the luminaires. Also the
number of lamps should preferably be more in the rear
half of the room than in the vicinity of windows. The
following steps may be followed for using Fig. 3 for
determining the number of fluorescent tubes required
for supplementary daylighting.
a) Determine fenestration percentage of the floor
area, that is,
Window Area
Floor Area
X100
b) In Fig. 3, refer to the curve corresponding to
the percent fenestration determined above
and the set of reflectances of ceiling, walls
and floor actually provided.
c) For the referred curve of Fig. 3 read, along
the ordinate, the number of 40 W fluorescent
tubes required, corresponding to the given
floor area on the abscissa.
4.3.4 For detailed information on the design aspects
and principles of artificial lighting, reference may be
made to good practice [8-1(2)].
4.3.5 For specific requirements for lighting of special
occupancies and areas, reference may be made to good
practice [8-1(5)].
4.3.6 Electrical installation aspect for artificial lighting
shall be in accordance with Part 8 'Building Services,
Section 2 Electrical and Allied Installations'.
4.4 Energy Conservation in Lighting
4.4.1 A substantial portion of the energy consumed
on lighting may be saved by utilization of daylight and
rational design of supplementary artificial lights.
30
NATIONAL BUILDING CODE OF INDIA
w
CO
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W
o
CO
LU
o:
o
ID
25
20-
15-
§ 10
o
U_
o
o:
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CO
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5 -
REFLECTANCE
CEILING
WALLS
FLOOR
0.7
0.7
0.3
0.7
0.5
0.3
0.5
0.5
0.3
.'*\'
*'
' *'
.' ^*
OPENINGS,
PERCENT
20
~~5
' --C^';^ :: ^0-- ^20
~T — «■
50
100
FLOOR AREA, m
150
2
- 1 — ' — r~
200
230
Fig. 3 Supplementary Artificial Lighting for 40W Fluorescent Tubes
4.4.2 Daytime use of artificial lights may be minimized
by proper design of windows for adequate daylight
indoors. Daylighting design should be according to 4.2.
4.4.3 Fenestration expressed as percentage of floor
area required for satisfactory visual performance of a
few tasks for different separation to height (S/H) ratio
of external obstructions such as opposite buildings may
be obtained from the design nomograph (Fig. 4). The
obstructions at a distance of three times their height or
more (S/H> 3) from a window facade are not
significant and a window facing such an obstruction
may be regarded as a case of unobstructed window.
4.4.3.1 The nomograph consists of horizontal lines
indicating fenestration percentage of floor area and
vertical lines indicating the separation to height ratio
of external obstructions such as opposite buildings.
Any vertical line for separation to height ratio other
than already shown in the nomograph (1.0, 2.0 and 3.0)
may be drawn by designer, if required. For cases where
there is no obstruction, the ordinate corresponding to
the value 3.0 may be used. The value of percentage
fenestration and separation to height ratio are marked
on left hand ordinate and abscissa respectively. The
illumination levels are marked on the right hand
ordinate. The values given within brackets are the
illumination levels on the work plane at centre and rear
of the room. The wattage of fluorescent tubes required
per square metre of the floor area for different
illumination levels is shown on each curve.
4.4.3.2 Following assumptions have been made in the
construction of the nomograph:
a) An average interior finish with ceiling white,
walls off white and floor grey has been
assumed.
b) Ceiling height of 3 m and room depths up to
10 m and floor area between 30 m 2 and 50 m 2
have been assumed. For floor area beyond
50 m 2 and less than 30 m 2 , the values of
percent fenestration as well as wattage per m 2
should be multiplied by a factor of 0.85 and
1.15 respectively.
c) It is assumed that windows are of metallic
sashes with louvers of width up to 600 mm
or a CHHAJJA (balcony projection) at ceiling
level of width up to 2.0 m. For wooden sashes,
the window area should be increased by a
factor of about 1.1.
d) Luminaires emanating more light in the
downward direction than upward direction
(such as reflectors with or without diffusing
plastics) and mounted at a height of 1.5 m to
2.0 m above the workplane have been
considered.
4.4.3.3 Method of use
The following steps shall be followed for the use of
nomograph:
a) Step 1 — Decide the desired illumination level
depending upon the task illumination
requirement in the proposed room and read
the value of watts per square metre on
the curve corresponding to the required
illumination level.
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
31
<
LL
LL
O
LU
o
z
LU
LU
£L
Z
o
I
(-
CO
LU
z
LU
LL
30
28
26
3 24
8 22
20
18
16
14
12
10
1.0
O
HO
co p
O
SEPARATION
Yfttf?4
\ r- WATTS PER SQ. m FLOOR AREA
\ OF SUPPLEMENTAL FLUORESCENT
\ TUBE LIGHTS
V \. 6 °
S. \54 \^
X^.8 >w
^w ^*^ NNN,, * ,,,,,,, *^^
^\4.2 ^S^
^**^^^E
^ "^^^-*^P
Xs^-6 "V
-*-^_ c
^^^0 ^^
*^^ — B
* A
2.0
SEPARATION TO HEIGHT RATIO
(360, 200)
200
(320, 175)
175
(280, 150)
150
(240, 125)
125
(200, 100)
100
3.0
(150, 75)
75
Fig. 4 Nomograph for Daylighting and Supplemental
Lighting Design of Building
z
LU
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is
5e
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O
5
b) Step 2 — Fix the vertical line corresponding
to the given separation to height ratio of
opposite buildings on the abscissa. From the
point of intersection of this vertical line and
the above curve move along horizontal, and
read the value of fenestration percent on the
left hand ordinate.
c) Step 3 — If the floor area is greater than
50 m 2 and less than 30 m 2 , the value of watts
per square metre as well as fenestration
percent may be easily determined for adequate
daylighting and supplemental artificial
lighting for design purposes. However, if the
fenestration provided is less than the required
value, the wattage of supplementary artificial
lights should be increased proportionately
to make up for the deficiency of natural
illumination.
4.4.4 For good distribution of day light on the working
plane in a room, window height, window width and
height of sill should be chosen in accordance with the
following recommendations:
a) In office buildings windows of height L2 m
or more in the center of a bay with sill level
at 1.0 to 1.2 m above floor and in residential
buildings windows of height 1.0 m to 1.1 m
with sill height as 0.9 m to 0.7 m above floor
are recommended for good distribution
of daylight indoors. Window width can
32
NATIONAL BUILDING CODE OF INDIA
accordingly be adjusted depending upon the
required fenestration percentage of the floor
area.
b) If the room depth is more than 10 m, windows
should be provided on opposite sides for
bilateral lighting.
c) It is desirable to have a white finish for ceiling
and off white (light colour) to white for walls.
There is about 7 percent improvement in
lighting levels in changing the finish of walls
from moderate to white.
4.4.5 For good distribution and integration of daylight
with artificial lights the following guidelines are
recommended:
a) Employ cool daylight fluorescent tubes for
supplementary artificial lighting.
b) Distribute luminaries with a separation of 2 m
to 3 m in each bay of 3 m to 4 m width.
c) Provide more supplementary lights such as
twin tube luminaries in work areas where
daylight is expected to be poor for example
in the rear region of a room having single
window and in the central region of a room
having windows on opposite walls. In
the vicinity of windows only single tube
luminaries should be provided.
4.4.6 Artificial Lighting
Energy conservation in lighting is effected by reducing
wastage and using energy effective lamps and
luminaires without sacrificing lighting quality.
Measures to be followed comprise utilization of
daylight, energy effective artificial lighting design by
providing required illumination where needed, turning
off artificial lights when not needed, maintaining
lighter finishes of ceiling, walls and furnishings, and
implementing periodic schedule for cleaning of
luminaires and group replacement of lamps at suitable
intervals. Choice of light sources with higher luminous
efficacy and luminaires with appropriate light
distribution is the most effective means of energy
saving in lighting. However, choice of light sources
also depends on the other lighting quality parameters
like colour rendering index and colour temperature or
appearance. For example, high pressure sodium vapour
lamps, which have very high luminous efficacy, are
not suitable for commercial interiors because of poor
colour rendering index and colour appearance, but are
highly desirable in heavy industries. Also the choice
of light sources depends on the mounting height in the
interiors. For example, fluorescent lamps are not
preferred for mounting beyond 7 m height, when high
pressure gas discharge lamps are preferred because of
better optical control due to their compact size.
4.4.6.1 Efficient artificial light sources and luminaires
Luminous efficacy of some of the lamps used in
lighting of buildings are given in Table 8 along with
average life in burning hours, Colour Rendering Index
and Colour Temperature.
Following recommendations may be followed in the
choice of light sources for different locations:
a) For supplementary artificial lighting of work
area in office building care should be taken
to use fluorescent lamps, which match with
colour temperature of the daylight.
b) For residential buildings fluorescent lamps
and/or CFLs of proper CRI and CCT are
recommended to match with the colours and
interior design of the room.
c) For commercial interiors, depending on the
mounting heights and interior design,
fluorescent lamps, CFLs and low wattage
metal halilde lamps are recommended. For
highlighting the displays in show windows,
hotels, etc, low wattage tubular or dichroic
reflector type halogen lamps can be used.
d) For industrial lighting, depending on the
mounting height and colour consideration
fluorescent lamps, high pressure mercury
vappour lamps or high pressure sodium
vapour lamps are recommended.
4.4.6.2 For the same lumen output, it is possible to
save 75 to 80 percent energy if GLS lamps are replaced
with CFL and 65 to 70 percent if replaced with
fluorescent lamps. Similar energy effective solutions
are to be chosen for every application area.
Similarly with white fluorescent tubes recommended
for corridors and staircases, the electrical consumption
reduces to 1/4.5 of the energy consumption with
incandescent lamps.
4.4.6.3 Efficient luminaire also plays an important
role for energy conservation in lighting. The choice
of a luminaire should be such that it is efficient
not only initially but also throughout its life.
Following luminaries are recommended for different
locations:
a) For offices semi-direct type of luminaries are
recommended so that both the work plane
illumination and surround luminance can be
effectively enhanced.
b) For corridors and staircases direct type
of luminaries with wide spread of light
distributions are recommended.
c) In residential buildings, bare fluorescent tubes
are recommended. Wherever the incandescent
lamps are employed, they should be provided
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
33
Table 8 Luminous Efficacy, Life, CRI and CCT of Light Sources
(Clm,?£> A. A. f\ 1 \
SI
No.
(0
Light Source
(2)
Efficacy
lm/W
(3)
Average Life
h
(4)
CRI
(5)
CCT
K
(6)
i) Incandescent lamps
GLS25 W-l 000 W
ii) Tungsten halogen incandescent lamps
*/r fl ;„o w«i* rtM *, r «^.
60 W-2 000 W
Low-voltage types with reflector have
lower wattages
111/ uuuito^nii laiiipo \i il.;
a) Standard lamps
38mm(T12)~
20 W-65 W
8-18
10% higher than
lamp
1000
2 000
100
100
2 800
2 8U0-3 200
18 W-58W
Cool daylight
Warm white
uj m-iiivopw lamyo
38mm(T12)
20 W-65 W
26 mm (T 8)
-LO TT -~>0 TT
iv) Compact Fluorescent Lamps (CFL)
5V-25 W
v) High pressure mercury vapour lamps
on \\7 Ann \\r
OU TT -**\J\J TT
vi) Blended — Light lamps
MLL100W-500W
vii) High Pressure Sodium Vapour Lamps
en \\r 1 nnr\ \\r
JU TY "I VW YT
viii) Metal halide lamps
35 W-2 000 W
61
5 000
72
6 500
67
5 000
57
3 5UU
88-104
12 000-18 000
85-95
2 700-6 500
40-80
8 000
Similar to
FTL
36-60
5000
45
4000
11-26
5000
61
3 600
69-130
10 000-15 000
23
2 000
69-83
10000
68-92
3 000-5 600
I me laoie inciuaes lamps anu waiiages currenuy m use in ouiiuings m muia.
^ l^uiiiiiiuuo ^in^m^ vaiita wiui nit- waiiagt ^i tuv laiup.
3 Av^rs^s lif* 3 values are from available Indian Standards. WTiere Indian Standard is not available values "iven are onl v indicative.
4 CRI and CCT values are only indicative.
5 For exact values, it is advisable to contact manufacturers.
with white enamelled conical reflectors at an
inclination of about 45° from vertical.
4.4.7 Cleaning Schedule for Window Panes and
Luminaires
Adequate schedule for cleaning of window panes and
luminaries will result in significant advantage of
enhanced daylight and lumen output from luminaries.
This will tend to reduce the duration over which
artificial lights will be used and minimize the wastage
of energy. Depending upon the location of the building
a minimum of three to six months interval for periodic
cleaning of luminaries and window panes is
recommended for maximum utilization of daylight and
artificial lights.
A A O ni^^t + ,-^7„ f„„ /!„#;«„,■„/ r ,*„/,*„
^.^.o i nuiULunir uia jut r\r t-tji^itii i^tgiud
There is a considerable wastage of electrical energy in
lighting of buildings due to carelessness in switching
off lights even when sufficient davliaht is available
indoors= In offices and commercial buildings^
occunants mav switch on lights in the morning and
keep them on throughout the day. When sufficient
daylight is available inside, suitable photo controls can
be employed to switch off the artificial lights and thus
prevent the wastage of energy.
A A t\ C„7 r»7.„^ _7i„-*„ O j. /CTIT7V
**.**.^ juiur rnuiuvuauiL dy&iems \or v /
Solar photovoltaic system enables direct conversion
of sunlight into electricity and is viable option for
lighting purpose in remote nongrid areas. The common
SPV lighting systems are:
Solar lantern.
a)
Tniv^rl f-\/rn» cnlir l-ir\m*=» lirrVifrinrr e\/et*=»m anrl
J. IJA^V* IJUV iJV7.I.t*± 11V1J1V 11^,111111^, tJJ LflVlll, U11U
u; ou'cci iigiiuiig system.
4.4.9.1 SPV lighting system should preferably be
provided with CFL for energy efficiency.
34
NATIONAL BUILDING CODE OF INDIA
4.4.9.2 Invertors used in buildings for supplying
electricity during the power cut period should be
charged through SPV system.
4.4.9.3 Regular maintenance of SPV system is
necessary for its satisfactory functioning.
5 VENTILATION
5.1 General
Ventilation of buildings is required to supply fresh air
for respiration of occupants, to dilute inside air to prevent
vitiation by body odours and to remove any products of
combustion or other contaminants in air and to provide
such thermal environments as will assist in the
maintenance of heat balance of the body in order to
prevent discomfort and injury to health of the occupants.
5.2 Design Considerations
5.2.1 Respiration
Supply of fresh air to provide oxygen for the human
body for elimination of waste products and to maintain
carbon dioxide concentration in the air within safe
limits rarely calls for special attention as enough outside
air for this purpose normally enters the areas of
occupancy through crevices and other openings.
5.2.1.1 In normal habitable rooms devoid of smoke
generating source, the content of carbon dioxide in air
rarely exceeds 0.5 percent to 1 percent and is, therefore,
incapable of producing any ill effect. The amount of
air required to keep the concentration down to 1 percent
is very small. The change in oxygen content is also
too small under normal conditions to have any ill
effects; the oxygen content may vary quite appreciably
without noticeable effect, if the carbon dioxide
concentration is unchanged.
5.2.2 Vitiation by Body Odours
Where no products of combustion or other contaminants
are to be removed from air, the amount of fresh air
required for dilution of inside air to prevent vitiation of
air by body odours, depends on the air space available
per person and the degree of physical activity; the
amount of air decreases as the air space available per
person increases, and it may vary from 20 m 3 to 30 m 3
per person per hour. In rooms occupied by only a small
number of persons such an air change will automatically
be attained in cool weather by normal leakage around
windows and other openings and this may easily be
secured in warm weather by keeping the openings open.
No standards have been laid down under the Factories
Act, 1948 as regards the amount of fresh air required
per worker or the number of air changes per hour.
Section 16 relating to over-crowding requires that at
least 14 m 3 to 16 m 3 of space shall be provided for
every worker and for the purpose of that section no
account shall be taken of any space in a work room
which is more than 4.25 m above the floor level.
NOTE — Vitiation of the atmosphere can also occur in factories
by odours given off due to contaminants of the product itself,
say for example, from tobacco processing in a *Bidi* factory.
Here the ventilation will have to be augmented to keep odours
within unobjectionable levels.
5.2.2.1 Recommended values for air changes
The standards of general ventilation are recommended/
based on maintenance of required oxygen, carbon
dioxide and other air quality levels and for the control
of body odours when no products of combustion or
other contaminants are present in the air; the values of
air changes should be as follows:
SI No. Application
Air Change per Hour
(1) (2)
(3)
1 . Assembly rooms
4-8
2. Bakeries
20-30
3. Banks/building societies
4-8
4. Bathrooms
6-10
5. Bedrooms
2-4
6. Billiard rooms
6-8
7. Boiler rooms
15-30
8. Cafes and coffee bars
10-12
9. Canteens
8-12
10. Cellars
3-10
11. Churches
1-3
12. Cinemas and theatres
10-15
13. Club rooms
12, Min
14. Compressor rooms
10-12
15. Conference rooms
8-12
16. Dairies
8-12
17. Dance halls
12, Min
18. Dye works
20-30
19. Electroplating shops
10-12
20. Engine rooms
15-30
21. Entrance halls
3-5
22. Factories and work shops
8-10
23. Foundries
15-30
24. Garages
6-8
25. Glasshouses
25-60
26. Gymnasium
6, Min
27. Hair dressing saloon
10-15
28. Hospitals-sterlizing
15-25
29. Hospital-wards
6-8
30. Hospital domestic
15-20
31. Laboratories
6-15
32. Launderettes
10-15
33. Laundries
10-30
34. Lavatories
6-15
35. Lecture theatres
5-8
36. Libraries
3-5
37. Living rooms
3-6
38. Mushroom houses
6-10
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
35
SI No.
(1)
Application
(2)
Air Change per Hour
(3)
39. Offices 6-10
40. Paint shops (not cellulose) 10-20
4 1 . Photo and X-ray dark room 10-15
42. Public house bars 12, Mm
43. Recording control rooms 15-25
44. Recording studios 10-12
45. Restaurants 8-12
46. Schoolrooms 5-7
47. Shops and supermarkets 8-15
48. Shower baths 15-20
49. Stores and warehouses 3-6
50. Squash courts 4, Min
51. Swimming baths 10-15
52. Toilets 6-10
53. Utility rooms 15-20
54. Welding shops 15-30
NOTE — The ventilation rates may be increased by 50 percent
where heavy smoking occurs or if the room is below ground.
5.2.3 Heat Balance of Body
Specially in hot weather, when thermal environment
inside the room is worsened by heat given off by
machinery, occupants and other sources, the prime
need for ventilation is to provide such thermal
environment as will assist in the maintenance of heat
balance of the body in order to prevent discomfort and
injury to health. Excess of heat either from increased
metabolism due to physical activity of persons or gains
from a hot environment has to be offset to maintain
normal body temperature (37°C). Heat exchange of
the human body with respect to the surroundings is
determined by the temperature and humidity gradient
between the skin and the surroundings and other
factors, such as age of persons, clothing, etc, and
the latter depends on air temperature (dry bulb
temperature), relative humidity, radiation from the
solid surroundings and rate of air movement. The
volume of outside air to be circulated through the room
is, therefore, governed by the physical considerations
of controlling the temperature, air distribution or air
movement. Air movement and air distribution may,
however, be achieved by recirculation of the inside air
rather than bringing in all outside air. However, fresh
air supply or the circulated air will reduce heat stress
by dissipating heat from body by evaporation of the
sweat, particularly when the relative humidity is high
and the air temperature is near body temperature.
5.2.3.1 Limits of comfort and heat tolerance
Thermal comfort is that condition of thermal environment
under which a person can maintain a body heat balance
at normal body temperature and without perceptible
sweating. Limits of comfort vary considerably according
to studies carried out in India and abroad. The thermal
comfort of a person lies between TSI values of 25°C
and 30°C with optimum condition at 27.5°C. Air
movement is necessary in hot and humid weather for
body cooling. A certain minimum desirable wind speed
is needed for achieving thermal comfort at different
temperatures and relative humidities. Such wind speeds
are given in Table 9. These are applicable to sedentary
work in offices and other places having no noticeable
sources of heat gain. Where somewhat warmer
conditions are prevalent, such as in godowns and
machine shops and work is of lighter intensity, and
higher temperatures can be tolerated without much
discomfort, minimum wind speeds for just acceptable
warm conditions are given in Table 10. For obtaining
values of indoor wind speed above 2.0 m/s, mechanical
means of ventilation may have to be adopted {see also
Part 8 'Building Services, Section 3 Air Conditioning,
Heating and Mechanical Ventilation').
Table 9 Desirable Wind Speeds (m/s) for
Thermal Comfort Conditions
{Clause 5.2.3.1)
Dry Bulb
Temperature,
Relative Humidity (Percentage)
■ i .^
°C
30
40
50
60
70
80
90
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
28
*
*
*
*
*
*
*
29
*
*
*
*
*
0.06
0.19
30
*
*
*
0.06
0.24
0.53
0.85
31
*
0.06
0.24
0.53
1.04
1.47
2.10
32
0.20
0.46
0.94
1.59
2.26
3.04
**
33
0.77
1.36
2.12
3.00
**
**
**
34
1.85
2.72
*•
**
**
**
**
35
3.20
•*
**
**
**
**
**
♦None
** Higher than those acceptable in practice.
Table 10 Minimum Wind Speeds (m/s) for Just
Acceptable Warm Conditions
(Clduse 5.2.3.1)
Dry Bulb
Temperature,
°C
Relative Humidity (Percentage)
30
4&f 50
60 70
80
90
(1)
(2)
(3) (4)
(5) (6)
(7)
(8)
28
*
* *
* *
*
*
29
*
* *
* *
*
*
30
*
* *
* *
*
*
31
*
* *
* *
0.06
0.23
32
*
* *
0.09 0.29
0.60
0.94
33
*
0.04 0.24
0.60 1.04
1.85
2.10
34
0.15
0.46 0.94
1.60 2.26
3.05
**
35
0.68
1.36 2.10
3.05 **
**
**
36
1.72
2.70 **
** **
**
*.*
*None
** Higher than those acceptable in practice.
36
NATIONAL BUILDING CODE OF INDIA
5.2.3.2 There will be a limit of heat tolerance when
air temperatures are excessive and the degree of
physical activity is high. This limit is determined when
the bodily heat balance is upset, that is, when the bodily
heat gain due to conduction, convection and the
radiation from the surroundings exceeds the bodily heat
loss, which is mostly by evaporation of sweat from
the surface of the body. The limits of heat tolerance
for Indian workers are based on the study conducted
by the Chief Adviser Factories, Government of India,
Ministry of Labour and are given in his report on
Thermal Stress in Textile Industry (Report No. 17)
issued in 1956. According to this Report, where
workers in industrial buildings wearing light clothing
are expected to do work of moderate severity with the
energy expenditure in the range 273 to 284 W, the
maximum wet bulb temperature shall not exceed 29°C
and adequate air movement subject to a minimum air
velocity of 30 m/min shall be provided, and in relation
to the dry bulb temperature, the wet bulb temperature
of air in the work room, as far as practicable, shall not
exceed that given in Table 11.
Table 11 Maximum Permissible Wet Bulb
Temperatures for Given Dry Bulb Temperatures
(Clause 5.2.3.2)
Dry Bulb Temperature
Maximum Wet-Bulb
°C
Temperature, °C
(1)
(2)
30
29.0
35
28.5
40
28.0
45
27.5
50
27.0
NOTES
1 These are limits beyond which the industry should not allow
the thermal conditions to go for more than 1 h continuously.
The limits are based on a series of studies conducted on Indian
subjects in psychrometric chamber and on other data on heat
casualties in earlier studies conducted in Kolar Gold Fields
and elsewhere.
2 Figures given in this table are not intended to convey that
human efficiency at 50 Q C will remain the same as at 30°C,
provided appropriate wet bulb temperatures are maintained.
Efficiency decreases with rise in the dry bulb temperature as
well, as much as possible. Long exposures to temperature of
50°C dry bulb/27°C wet bulb may prove dangerous.
3 Refrigeration or some other method of cooling is
recommended in all cases where conditions would be worse
than those shown in this table.
5.3 Methods of Ventilation
General ventilation involves providing a building with
relatively large quantities of outside air in order to
improve general environment of the building. This may
be achieved in one of the following ways:
a) Natural supply and natural exhaust of air;
b) Natural supply and mechanical exhaust of air;
c) Mechanical supply and natural exhaust of air;
and
d) Mechanical supply and mechanical exhaust
of air.
5.3.1 Control of Heat
Although it is recognized that general ventilation is
one of the most effective methods of improving thermal
environmental conditions in factories, in many
situations, the application of ventilation should be
preceded by and considered along with some of the
following other methods of control. This would
facilitate better design of buildings for general
ventilation, either natural or mechanical or both, and
also reduce their cost.
5.3.1.1 Isolation
Sometimes it is possible to locate heat producing
equipment, such as furnaces in such a position as would
expose only a small number of workers to hot
environment. As far as practicable, such sources of heat
in factories should be isolated.
In situations where relatively few people are exposed
to severe heat stress and their activities are confined to
limited areas as in the case of rolling mill operators
and crane operators, it may be possible to enclose the
work areas and provide spot cooling or supply
conditioned air to such enclosures.
5.3.1.2 Insulation
A considerable portion of heat in many factories is due
to the solar radiation falling on the roof surfaces, which,
in turn, radiate heat inside the building. In such
situations, insulations of the roof or providing a false
ceiling or double roofing would be very effective in
controlling heat. Some reduction can also be achieved
by painting the roof in heat reflective shades.
Hot surfaces of equipment, such as pipes, vessels, etc,
in the building should also be insulated to reduce their
surface temperature.
5.3.1.3 Substitution
Sometimes, it is possible to substitute a hot process by
a method that involves application of localized or more
efficiently controlled method of heating. Examples
include induction hardening instead of conventional
heat treatment, cold riveting or spot welding instead
of hot riveting, etc.
5.3.1.4 Radiant shielding
Hot surfaces, such as layers of molten metal emanate
radiant heat, which can best be controlled by placing a
shield having a highly reflecting surface between the
source of heat and the worker, so that a major portion
of the heat falling on the shield is reflected back to the
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
37
source. Surfaces such as of tin and aluminium have
been used as materials for shields. The efficiency of
the shield does not depend on its thickness, but on the
reflectivity and emissivity of its surface. Care should
be taken to see that the shield is not heated up by
conduction and for this purpose adequate provision
should be made for the free flow upwards of the heated
air between the hot surface and the shield by leaving
the necessary air space and providing opening at the
top and the bottom of the sides.
5.3.2 Volume of Air Required
The volume of air required shall be calculated by using
both the sensible heat or latent heat gain as the basis.
The larger of the two figures obtained should be used
in actual practice.
5.3.2.1 Volume of air required for removing sensible
heat
When the amount of sensible heat given off by different
sources, namely, the sun, the manufacturing processes,
machinery, occupants and other sources, is known and
a suitable value for the allowable temperature rise is
assumed, the volume of outside air to be provided for
removing the sensible heat may be calculated from:
a =
2.976 8*
t
where
Q { = Quantity of air in m 3 /h,
K — Sensible heat gained in W, and
t = Allowable temperature rise in °C.
5.3.2.2 Temperature rise refers mainly to the
difference between the air temperatures at the outlet
(roof exit) and at the inlet openings for outside air. As
very little data exist on allowable temperature rise
values for supply of outside air in summer months, the
values given in Table 12 related to industrial buildings
may be used for general guidance.
Table 12 Allowable Temperature Rise Values
{Clause 5.3.2.2)
Height of Outlet Opening
(1)
Temperature Rise
(2)
6
9
12
3 to 4.5
4.5 to 6.5
6.5 to 11
NOTES
1 The conditions are limited to light or medium heavy
manufacturing processes* freedom from radiant heat and inlet
openings not more than 3 to 4.5 in above floor level.
2 At the working zone between floor level and 1.5 m above
floor level, the recommended maximum allowable temperature
rise for air is 2°C to 3°C above the air temperature at the inlet
openings.
5.3.2.3 Volume of air required for removing latent
heat
If the latent heat gained from the manufacturing
processes and occupants is also known and a suitable
value for the allowable rise in the vapour pressure is
assumed:
■a*
_ 4l2X26x*: i
where
Q 2 = Quantity of air in mVh,
K x = Latent heat gained in W, and
h = Allowable vapour pressure difference in mm
of mercury.
NOTE — In majority of the cases, the sensible heat gain
will far exceed the latent heat gain, so that the amount of
outside air to be drawn by ventilating equipment can be
calculated in most cases on the basis of the equation given
in 5.3.2.1.
5.3.2.4 Ventilation is also expressed as mVh per m 2
of floor area. This relationship fails to evaluate the
actual heat relief provided by a ventilation system, but
it does give a relationship which is independent of
building height. This is a more rational approach,
because, with the same internal load, the same amount
of ventilation air, properly applied to the work zone
with adequate velocity, will provide the desired heat
relief quite independently of the ceiling height of the
space, with few exceptions. Ventilation rates of 30 to
60 mVh per m 2 have been found to give good results
in many plants.
5.4 Natural Ventilation
The rate of ventilation by natural means through
windows or other openings depends on:
a) direction and velocity of wind outside and
sizes and disposition of openings (wind
action), and
b) convection effects arising from temperature
of vapour pressure difference (or both)
between inside and outside the room and the
difference of height between the outlet and
inlet openings (stack effect).
5.4.1 Ventilation of Non-industrial Buildings
Ventilation in non-industrial buildings due to stack
effect, unless there is a significant internal load, could
be neglected, except in cold regions, and wind action
may be assumed to be predominant.
5.4.1.1 In hot dry regions, the main problem in summer
is to provide protection from sun's heat so as to keep
the indoor temperature lower than those outside under
the sun. For this purpose windows and other openings
38
NATIONAL BUILDING CODE OF INDIA
are generally kept closed during day time and only
minimum ventilation is provided for the control of
odours or for removal of products of combustion.
5.4.1.2 In warm humid regions, the problem in the
design of non-industrial buildings is to provide free
passage of air to keep the indoor temperature as near
to those outside in the shade as possible, and for this
purpose the buildings are oriented to face the direction
of prevailing winds and windows and other openings
are kept open on both windward and leeward sides.
5.4.1.3 In winter months in cold regions, the windows
and other openings are generally kept shut, particularly
during night; and ventilation necessary for the control
of odours and for the removal of products of
combustion can be achieved either by stack action or
by some infilteration of outside air due to wind action.
5.4.2 Ventilation of Industrial Buildings
In providing natural ventilation of all industrial
buildings having significant internal heat loads due to
manufacturing process, proper consideration should be
given to the size and distribution of windows and other
inlet openings in relation to outlet openings so as to
give, with due regard to orientation, prevailing
winds, size and configuration of the building and
manufacturing processes carried on, maximum
possible control of thermal environment.
5.4.2.1 In the case of industrial buildings wider than
30 m, the ventilation through windows may be
augmented by roof ventilation.
5.4.3 Design Guidelines for Natural Ventilation
5.4.3.1 By wind action
i) A building need not necessarily be oriented
perpendicular to the prevailing outdoor wind;
it may be oriented at any convenient angle
between 0° and 30° without loosing any
beneficial aspect of the breeze. If the
prevailing wind is from East or West, building
may be oriented at 45° to the incident wind
so as to diminish the solar heat without much
reduction in air motion indoors.
ii) Inlet openings in the buildings should be well
distributed and should be located on the
windward side at a low level, and outlet
openings should be located on the leeward
side. Inlet and outlet openings at high levels
may only clear the top air at that level without
producing air movement at the level of
occupancy.
iii) Maximum air movement at a particular plane
is achieved by keeping the sill height of the
opening at 85 percent of the critical height
(such as head level) for the following
recommended levels of occupancy:
1) For sitting on chair 0.75 m,
2) For sitting on bed 0.60 m, and
3) For sitting on floor 0.40 m.
iv) Inlet openings should not as far as possible
be obstructed by adjoining buildings, trees,
sign boards or other obstructions or by
partitions inside in the path of air flow.
v) In rooms of normal size having identical
windows on opposite walls the average indoor
air speed increases rapidly by increasing the
width of window up to two-third of the wall
width; beyond that the increase is in much
smaller proportion than the increase of the
window width. The air motion in the working
zone is maximum when window height is
1.1m. Further increase in window height
promotes air motion at higher level of
window, but does not contribute additional
benefits as regards air motion in the
occupancy zones in buildings.
vi) Greatest flow per unit area of openings is
obtained by using inlet and outlet openings
of nearby equal areas at the same level.
vii) For a total area of openings (inlet and outlet)
of 20 percent to 30 percent of floor area, the
average indoor wind velocity is around
30 percent of outdoor velocity. Further
increase in window size increases the
available velocity but not in the same
proportion. In fact, even under most favourable
conditions the maximum average indoor
wind speed does not exceed 40 percent of
outdoor velocity,
viii) Where the direction of wind is quite constant
and dependable, the size of the inlet should
be kept within 30 to 50 percent of the total
area of openings and the building should be
oriented perpendicular to the incident wind.
Where direction of the wind is quite variable
the openings may be arranged so that as far
as possible there is approximately equal area
on all sides. Thus no matter what the wind
direction be, there 'would be some openings
directly exposed to wind pressure and others
to air suction and effective air movement
through the building would be assured.
ix) Windows of living rooms should open directly
to an open space. In places where building
sites are restricted, open space may have to
be created in the buildings by providing
adequate courtyards.
x) In the case of rooms with only one wall
exposed to outside, provision of two windows
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
39
on that wall is preferred to that of a single
window,
xi) Windows located diagonally opposite to each
other with the windward window near the
upstream corner give better performance than
other window arrangements for most of the
building orientations.
xii) Horizontal louvers, that is a sunshade, atop a
window deflects the incident wind upward
and reduces air motion in the zone of
occupancy. A horizontal slot between the wall
and horizontal louver prevents upward
deflection of air in the interior of rooms.
Provision of inverted L type (r) louver
increases the room air motion provided that
the vertical projection does not obstruct the
incident wind.
xiii) Provision of horizontal sashes inclined at an
angle of 45° in appropriate direction helps to
promote the indoor air motion. Sashes
projecting outward are more effective than
projecting inward.
xiv) Air motion at working plane 0.4 m above the
floor can be enhanced by 30 percent using a
pelmet type wind deflector.
xv) Roof overhangs help promoting air motion
in the working zone inside buildings.
xvi) VERANDAH open on three sides is to be
preferred since it causes an increase in the
room air motion for most of the orientations
of the building with respect to the outdoor
wind,
xvii) A partition placed parallel to the incident wind
has little influence on the pattern of the air
flow, but when located perpendicular to the
main flow, the same partition creates a wind
shadow. Provision of a partition with spacing
of 0.3 m underneath, helps augmenting air
motion near floor level in the leeward
compartment of wide span buildings,
xviii) Air motion in a building unit having windows
tangential to the incident wind is accelerated
when another unit is located at end-on
position on down stream side.
xix) Air motion in two wings oriented parallel
to the prevailing breeze is promoted by
connecting them with a block on downstream
side.
xx) Air motion in a building is not affected by
constructing another building of equal or
smaller height on the leeward side; but it is
slightly reduced if the leeward building is
taller than the windward block.
xxi) Air motion in a shielded building is less than
that in an unobstructed building. To minimize
shielding effect, the distances between two
rows should be 8 H for semi-detached houses
and 10 H for long rows houses. However, for
smaller spacing the shielding effect is also
diminished by raising the height of the
shielded building.
xxii) Hedges and shrubs defect the air away from
the inlet openings and cause a reduction in
indoor air motion. These elements should not
be planted at a distance of about 8 m from the
building because the induced air motion is
reduced to minimum in that case. However,
air motion in the leeward part of the building
can be enhanced by planting a low hedge at a
distance of 2 m from the building.
xxiii) Trees with large foliage mass having trunk
bare of branches up to the top level of
window, deflect the outdoor wind downwards
and promotes air motion in the leeward
portion of buildings.
xxiv) Ventilation conditions indoors can be
ameliorated by constructing buildings on .
earth mound having a slant surface with a
slope of 10° on upstream side.
xxv) In case of industrial buildings the window
height should be about 1.6 m and width about
two-third of wall width. These should be
located at a height of 1.1 m above the floor.
In addition to this, openings around 0.9 m
high should be provided over two-third length
of the glazed area in the roof lights.
xxvi) Height of industrial buildings, although
determined by the requirements of industrial
processes involved, generally kept large
enough to protect the workers against hot
stagnant air below the ceiling as also to dilute
the concentration of contaminant inside.
However, if high level openings in roof or
walls are provided, building height can be
reduced to 4 m without in any way impairing
the ventilation performance.
NOTE — For data on outdoor wind speeds at a place,
reference may be made to The Climatic Data Handbook
prepared by Central Building Research Institute,
Roorkee, 1999'.
5.4.3.2 By stack effect
Natural ventilation by stack effect occurs when air
inside a building is at a different temperature than air
outside. Thus in heated buildings or in buildings
wherein hot processes are carried on and in ordinary
buildings during summer nights and during
premonsoon periods, the inside temperature is higher
than that of outside, cool outside air will tend to enter
40
NATIONAL BUILDING CODE OF INDIA
tnrougn openings at low level ana warm air win tenu
to leave through openings at high level. It would,
therefore, be advantageous to provide ventilators as
close to ceilings as possible. Ventilators can also be
provided in roofs as, for example, cowi, ventpipe,
covercu roo± anu Huge vent.
5.5 Mechanical Ventilation
The requirements of mechanical ventilation shaii
be in accordance with Part 8 'Building Services,
Section 3 Air Conditioning, Heating and Mechanical
Ventilation 1 .
5.6 Determinin° Rate of Ventilation
5.6.1 Natural Ventilation
This is difficult to measure as it varies from time-to-
time. The amount of outside air through windows and
other openings depends on the direction and velocity
of wind outside (wind action) and/or convection
effects arising from temperature or vapour pressure
differences (or both) between inside and outside of the
building (stack effect).
5.6.1.1 Wind action
For determining the rate of ventilation based on wind
action the wind may be assumed to come from any
direction within 45° of the direction of prevailing wind.
Ventilation due to external wind is given by the
following formula:
n — ya\/
where
f} — t? nt^> rtf air flr»w in m 3 /h*
l\ — \_,L*dilUJ. till vji t-iit-^n v^iiA^aa, vvuiLii ilia.}' \j\^
ririaninfrp nT»H f\ *X fnr \xr\r\A it in rmfT^t* IpOC
A = Free area of inlet openings in in~; anu
V = Wind speed in m/'h.
NOTE — For wind data at a place, the local Meteorological
Department may be consulted.
5.6.1.2 Stack effect
Ventilation due to convection effects arising ircin
temperature difference between insiue anu outsiue is
given uy.
n = l.(\AJh(t -t }
Q = Rate of air flow in m 3 /h;
A = Free area of inlet openings in m 2 ;
h - Vertical distance between inlets and outlets
in m;
Average tcuipciature of indoor air at ueigut
t = temperature or outaoor air in ~c
NOTE — The equation is based on 0.65 effectiveness of
openings. This should be reduced to 0.50 if conditions are not
fnv'{'»iirQh]g t
5.6.1.3 When areas of inlet and outlet openings are
unequal, the value of A may be calculated using the
equation
1
1
5.6.1.4 When both forces (wind and thermal) act
together in the same direction, even without
interference, the resulting air flow is not equal to the
two flows estimated separately. Flow through any
opening is proportional to the square root of the sum
of the two heads acting on that opening.
Wind velocity and direction, outdoor temperature, and
indoor distribution can not be predicted with certainty,
and refinement in calculation is not justified. A simple
method is calculate the sum of the flows produced by
each force separately. Then using the ratio of the flow
produced by thermal forces to the aforementioned sum,
the actual flow due to the combined forces can be
approximated from Fig. 5. When the two flows are
equal, the actual flow is about 30 percent greater than
the flow caused by either force acting independently
(see Fig. 5).
si
U- LU
U. £
a. Q
P UJ
zd <*■
se
§l
_J UJ
U- I-
§3
\
\
\
I
1
1
1
r
\
\
\
\
\
\
V
N
20
40
60
80
100
DiFhtKtNCfc A3 PERCENT OF TOTAL
Fig. 5 Determination of Flow Caused
by Combined Forces of Wind and Temperature
Difference
Judgement is necessarv for orooer location of ooenines
in a building specially in the roof, where heat, smoke
and fumes are to be removed. Usually, windward
monitor openings should be closed, but if wind is so
PAWT 8 Rnn.niNfiSF.WVir.ES — SECTION 1 LIGHTING AND VENTILATION
41
slight that temperature head can overcome it, all
openings may be opened.
5.6.1,5 For method for determining the rate of
ventilation based on probable indoor wind speed
with typical illustrative example for residential
building, reference may be made to good practice
[8-1(6)].
5.6.2 Mechanical Ventilation
The determination of rate of ventilation in case of
mechanical ventilation shall be done in accordance
with Part 8 'Building Services, Section 3 Air
Conditioning, Heating and Mechanical Ventilation'.
5.6.3 Combined Effect of Different Methods of
Ventilation
When combination of two or more methods of general
ventilation is used, the total rate of ventilation shall be
reckoned as the highest of the following three, and this
rule shall be followed until an exact formula is
established by research:
a) 1.25 times the rate of natural ventilation,
b) Rate of positive ventilation, and
c) Rate of exhaust of air.
5.6.4 Air Movement
The rate of air movement of turbulent type at the
working zone shall be measured either with a Kata
thermometer (dry silvered type) or heated thermometer
or properly calibrated thermocouple anemometer.
Whereas anemometer gives the air velocity directly,
the Kata thermometer and heated thermometer give
cooling power of air and the rate of air movement is
found by reference to a suitable nomogram using the
ambient temperature.
5.7 Energy Conservation in Ventilation System
5.7.1 Maximum possible use should be made of wind
induced natural ventilation. This may be accomplished
by following the design guidelines given in 5.7.1.1.
5.7.1.1 Adequate number of circulating fans should be
installed to serve all interior working areas during summer
months in the hot dry and warm humid regions to provide
necessary air movement at times when ventilation due to
wind action alone does not afford sufficient relief.
5.7.1.1.1 The capacity of a ceiling fan to meet the
requirement of a room with the longer dimension D
metres should be about 55 D m 3 /min.
5.7.1.1.2 The height of fan blades above the floor
should be (3H + W)/4, where H is the height of the
room, and W is the height of work plane.
5.7.1.1.3 The minimum distance between fan blades
and the ceiling should be about 0.3 metre.
5.7.2 Electronic regulators should be used instead of
resistance type regulators for controlling the speed of fans.
5.7.3 When actual ventilated zone does not cover the
entire room area, then optimum size of ceiling fan
should be chosen based on the actual usable area of
room, rather than the total floor area of the room. Thus
smaller size of fan can be employed and energy saving
could be achieved.
5.7.4 Power consumption by larger fans is obviously
higher, but their power consumption per square metre
of floor area is less and service value higher. Evidently,
improper use of fans irrespective of the rooms
dimensions is likely to result in higher power
consumption. From the point of view of energy
consumption, the number of fans and the optimum sizes
for rooms of different dimensions are given in Table 13.
Table 13 Optimum Size/Number of Fans for Rooms of Different Sizes
(Clause 5.1 A) .
Room
Width
Room Length
/
m
4m
5m
6m
7m
8m
9m
10 m
11m
12m
14m
16 m
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9) ,
(10)
(11)
(12)
3
1200/1
1 400/1
1500/1
1 050/2
1 200/2
1400/2
1400/2
1400/2
A 200/3
1400/3
1400/3
4
1200/1
1 400/1
1200/2
1200/2
1 200/2
1400/2
1400/2
1500/2
1 200/3
1400/3
1 500/3
5
1 400/1
1 400/1
1400/2
1400/2
1 400/2
1400/2
1400/2
1500/2
1400/3
1400/3
1500/3
6
1 200/2
1400/2
900/4
1 050/4
1 200/4
1400/4
1400/4
1500/4
1200/6
1 400/6
1 500/6
7
1 200/2
1400/2
1050/4
1 050/4
1 200/4
1400/4
1400/4
1500/4
1200/6
1 400/6
1500/6
8
1 200/2
1 400/2
1 200/4
1 200/4
1200/4
1 400/4
1400/4
1 500/4
1200/6
1 400/6
1 500/6
9
1 400/2
1400/2
1400/4
1400/4
1400/4
1400/4
1400/4
1500/4
1400/6
1400/6
1500/6
10
1 400/2
1 400/2
1400/4
1400/4
1400/4
1400/4
1400/4
1 500/4
1400/6
1400/6
1500/6
11
1 500/2
1500/2
1500/4
1500/4
1500/4
1500/4
1500/4
1500/4
1500/6
1 500/6
1 500/6
12
1 200/3
1400/3
1200/6
1200/6
1200/6
1400/6
1400/6
1500/6
1 200/7
1400/9
1400/9
13
14
1 400/3
1400/3
1400/3
1400/3
1200/6
1400/6
1200/6
1 400/6
1200/6
1 400/6
1400/6
1400/6
1400/6
1400/6
1500/6
1500/6
1400/9
1400/9
1400/9
1400/9
1500/9
1500/9
42
NATIONAL BUILDING CODE OF INDIA
ANNEX A
(Clauses 4.2.5, 4.2.5.2, 4.2.5.3 and 4.2.5 A)
SKY COMPONENT TABLES
A-l DESCRIPTION OF TABLES
A- 1.1 The three sky component tables are as given
below:
Table 14 Percentage sky components on the
horizontal plane due to a vertical
rectangular opening for the clear
design sky
Table 15 Percentage sky components on the
vertical plane perpendicular to a
vertical rectangular opening for the
clear design sky
Table 16 Percentage sky components on the
vertical plane parallel to a vertical
rectangular opening for the clear
design sky
A-1.2 All the tables are for an unglazed opening
illuminated by the clear design sky.
A- 1.3 The values tabulated are the components at a
point P distant from the opening on a line perpendicular
to the plane of the opening through one of its lower
corners, and / and h are the width and height
respectively of the rectangular opening (see Fig. 6).
/
1
1
D
C
•c
1
'
A
B
Fig. 6
A-1.4 Sky component for different hid and lid values
are tabulated, that is, for windows of different size and
for different distances of the point P from the window.
A-1.5 By suitable combination of the values obtained
from the three tables, for a given point for a given
window, the sky component in any plane passing
through the point may be obtained.
A-1.6 Method of Using the Tables
A- 1.6.1 Method of using the Tables to get the sky
component at given point is explained with help of the
following example.
A-l.6.2 Example
It is desired to calculate the sky component due to a
vertical window ABCD with width 1.8 m and height
1 .5 m at a point P on a horizontal plane 3.0 m from the
window wall located as shown in Fig. 7. Foot of the
perpendicular N is 0.6 m below the sill and 0.9 m to
the left of AD.
Fig. 7
Consider ABCD extended to NB'CD'
1) For NB'CD'
lid =(1.8 + 0.9)/3 = 0.9
hid = (1.5 + 0.6)/3 = 0.7
F x = 5 JOS percent (from Table 15)
2) For NA'DD'
lid =0.9/3 = 0.3
hid =(1.5 + 0.6)/3 = 0.7
F 2 = 2.441 percent (from Table 15)
3) For NB'BA'
lid = (1.8 + 0.9)/3=0.9
hid = 0.6/3 = 0.2
F 3 = 0.878 percent (from Table 15)
4) For NA'AA'
lid =0.9/3 = 0.3
hid = 0.6/3 = 0.2
F 4 = 0.403 percent (from Table 15)
Since ABCD = NB'CD'-NA'DD'-NB'BA'+NA'AA'
Sky Component F
= F r F 2 -F 3+ F 4
= 5.708-2.441-0.878+0.403
= 2.792
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
43
■fc*
■fc*
Table 14 Percentage Sky Components on the Horizontal Plane Due to a Verticle Rectandular
Opeining for the Clear Design Sky
(Clause A-1.5)
M+OA 0.2 0,3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 3.0 4.0 5.0 10.0 INF
h/d
I
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25) (26)
0.1 0.036 0.071 0.104 0.133 0.158 0.179 0.198 0.213 0.225 0.235 0.243 0.250 0.256 0.261 0.264 0.268 0.270 0.272 0.274 0.276 0.284 0.286 0.287 0.288 0.288
0.2 0.141 0.277 0.403 0.516 0.614 0.699 0.770 0.829 0.878 0.918 0.950 0.977 0.999 1.018 1,033 1.046 1.056 1.065 1.072 1.079 1.110 1.118 1.122 1.125 1.125
0.3 0.300 0.589 0.859 1.102 1.315 1.499 1.653 1.782 1.888 1.976 2.048 2.108 2.157 2.197 2.231 2.259 2.282 2,302 2.318 2.333 2.401 2.421 2.429 2.436 2.437
0.4 0.460 0.905 1.322 1.702 2.041 2.337 2.590 2.804 2.984 3.134 3.258 3.361 3.446 3.516 3.574 3.623 3.664 3.699 3.728 3.753 3.873 3.909 3.922 3.935 3.937
0,5 0.604 1.189 1.741 2.247 2.700 3.099 3.444 3.740 3.992 4.204 3.383 4.553 4.659 4.765 4.853 4.928 4.990 5.043 5.088 5.126 5.312 5.366 5.387 5.408 5.410
0.6 0.732 1.443 2.114 2.732 3.289 3.781 4.211 4.582 4.900 5.171 5.401 5.5% 5.761 5.901 6.020 6.121 6.208 6.281 6.344 6.397 6.661 6.739 6.769 6.798 6.802
0.7 0.844 1.665 2.441 3.159 3.808 4.385 4.891 5.330 5.708 6.034 6.311 6.548 6.751 6.924 7.071 7.198 7.307 7.400 7.481 7.551 7.902 8.006 8.047 8.087 8.092
0.8 0.942 1.858 2.727 3.532 4.262 4.914 5.488 5.989 6.423 6.798 7.119 7.395 7.632 7,836 8.011 8.162 8.292 8.405 8.502 8.587 9.029 9.164 9.217 9.268 9.276
0.9 1.026 2.025 2.974 3.855 4.657 5.375 6.011 6.567 7.051 7.470 7.832 8.144 8.413 8,645 8.846 9.019 9.170 9.301 9.415 9.515 10.045 10.214 10.280 10.345 10.355
1.0 1.099 2.169 3.188 4.135 5.000 5.776 6.465 7.071 7.600 8.060 8.458 8.803 9.102 9.361 9.585 9.780 9.950 10.098 10.228 10.343 10.957 11.162 11.243 11.323 11.335
1.1 1.161 2.294 3.372 4.377 5.296 6.124 6.861 7.510 8.079 8.576 9.008 9.383 9.709 9.992 10.239 10.454 10.642 10.806 10.951 11.078 11.776 12.017 12.114 12.209 12.224
1.2 1.215 2.401 3.531 4.586 5.553 6.425 7.204 7.893 8.498 9.027 9.489 9.892 10.243 10.549 10.816 11.050 11.254 11.434 11.593 11.732 12.509 12.786 12.900 13.013 13.030
1.3 1.262 2.493 3.668 4.767 5.775 6.687 7.503 8.226 8.863 9.422 9.912 10.339 10.713 11.040 11.326 11.577 11.797 11.992 12.163 12.314 13.167 13.478 13.609 13.742 13.762
1.4 1302 2.573 3.787 4.924 5.968 6.915 7.764 8.517 9.^83 9.769 10.283 10.733 11.127 11.473 11.777 12.044 12.279 12.487 12.670 12.833 13.758 14.102 14.251 14.404 14.427
1.5 1.337 2.643 3.891 5.060 6.136 7.114 7.991 8.772 9.664 10.073 10.609 11.080 11.493 11.857 12.176 12.458 12.707 12.927 13.122 13.295 14.289 14.666 14.832 15.006 15.033
1.6 1.367 2.703 3.981 5.179 6.283 7.287 8.190 8.996 9.710 10.341 10.897 11.386 11.817 12.196 12.531 12.826 13.088 13.319 13.525 13.708 14.768 15.176 15.359 15.555 15.585
j> 1.7 1394 2.756 4.060 5.283 6.412 7.440 8.366 9.192 9.927 10.577 11.151 11.657 12.104 12.498 12.846 13.154 13.427 13.669 13.885 14.078 15.199 15.638 15.838 16.056 16.091
§ 1.8 1.417 2.803 4.129 5.375 6.526 7.574 8.520 9366 10.119 10.786 11.376 11.898 12.359 12.766 13.127 13.446 13.730 13.983 14.208 14.409 15.590 16.058 16.274 16.516 16.554
| 1.9 1.438 2.844 4.190 5.456 6.626 7.693 8.&6 9.520 10.289 10.972 11.577 12.112 12.587 13.006 13.378 13.708 14.002 14.264 14.498 14.707 15.944 16.441 16.673 16.937 16.980
W 2.0 1.456 2.880 4.244 5.527 6.714 7/798 8.778 9.656 10.440 11.137 11.755 12.303 12.789 13.220 13.603 13.943 14.246 14.516 14.758 14.975 16.265 16.790 17.037 17.325 17.372
P 3.0 1.559 3.087 4.553 5.937 7.223 8.403 9.478 10.448 11321 12.103 12.804 13.431 13.993 14.496 14.947 15.333 15.718 16.048 16346 16.676 18301 19.051 19.432 19.943 20.046
| 4.0 1.600 3.168 4.676 6.100 7.426 8.646 9.759 10.768 11.678 12.498 13.235 13.897 14.493 15.030 15.514 15.951 16.347 16.706 17.033 17.330 19.241 20.142 20.623 21322 21.495
£ 5.0 1.620 3.208 4.735 6.179 7.525 8.765 9.897 10.925 11.854 12.693 13.448 14.128 14.742 15.296 15.798 16.252 16.664 17.040 17382 17.695 19.740 20.740 21.293 22.148 22393
§ 10.0 1.648 3.263 4.818 6.289 7.662 8.930 10.089 11.144 12.100 12.965 13.747 14.454 15.094 15.674 16.201 16.681 17.118 17.518 17.885 18.222 20.491 21.681 22.390 23.676 24.238
S INF 1.657 3.282 4.846 6327 7.710 8.986 10.155 11.220 12.186 13.060 13.851 14.567 15.217 15.806 16.342 16.831 17.278 17.688 18.064 18.410 20.770 22.046 22.838 24.463 26.111
*] . — ',.:. "
£ Table 15 Percentage Sky Components on the Vertical Plane Perpendicular to a
J5j Vertical Rectandular Opening for the Clear Design Sky
(Clauses A-1.5 and A-l.6.2)
w
6 ftf->0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0,9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 3.0 4.0 5.0 10.0 INF
| (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25) (26)
so __,
£ 0.1 0.036 0.141 0.303 0.506 0.734 0.971 1.207 1.432 1.643 2.836 1.011 2.168 2.308 2.433 2.544 2.642 2.730 2.808 2.878 2.940 3.309 3.461 3.536 3.641 3.678
5 0.2 0.071 0.277 0.594 0.993 1.442 1.910 2.374 2.820 3.236 3.618 3.964 4.276 4.554 4.802 5.022 5.219 5.393 5.549 5.688 5.812 6.547 6.850 7.000 7.211 7.284
^ 0.3 0.103 0.401 0.863 1.445 2.100 2.793 3.475 4.180 4.743 5.306 5.818 6.278 6.690 7.058 7.385 7.677 7.936 8.168 8.375 8.560 9.657 10.110 10.335 10.651 10.760
n 0.4 0.126 0.491 1.059 1.779 2.597 3.460 4.326 5.166 5.958 6.691 7.359 7.967 8.507 8.900 9.420 9.804 10.146 10.451 10.724 10.968 12.421 13.024 13.323 13.743 13.889
O 0.5 0.142 0.554 1,197 2.015 2.947 3.937 4.938 5.914 6.842 7.707 85& 9.228 9.883 10.472 10.999 11.476 11.897 12.273 12.610 12.912 14.712 15.462 15.835 16.360 16.542
2 0.6 0.154 0.600 1.298 2.187 3.204 4.288 5.389 6.468 7.498 8.464 9.358 10.177 10.922 11.596 12.204 12.752 13.244 13.686 14.084 14.441 16.583 17.478 17.924 18.552 18.771
E 0.7 0.162 0.634 1.372 2.316 3.397 4.552 5.729 6.887 7.997 9.042 10.013 10.907 11.723 12.465 13.138 13.746 14.296 14.793 15.241 15.646 18.111 19.148 19.665 20.397 20.653
O
SB 0.8 0.169 0.660 1.429 2.413 3.543 4.754 5.990 7.209 8.382 9.490 10.523 11.476 12.350 13.147 13.873 14.531 15.129 15.670 16.161 16.606 19.361 20.538 21.127 21.961 22.253
H
2 0.9 0.174 0.680 1.472 2.487 3.655 4.909 6.192 7.460 8.683 9.841 10.924 11.926 12.847 13.690 14.459 15.159 15.796 16.375 16.902 17.381 20.387 21.701 22360 23.397 23.625
O
> 1.0 0.178 0.695 1.505 2.545 3.743 5.030 6.350 7.657 8.921 10.120 11.243 12.284 13.245 14.126 14.931 15.666 16.337 16.948 17.504 18.012 21.237 22.680 23.408 24.446 24.810
O 1.1 0.181 0.707 1.532 2.591 3.812 5.126 6.475 7.814 9.110 10.342 11.498 12.573 13.356 14.478 15.314 16.079 16.778 17.416 17.999 18.531 21.946 23.508 24303 25.441 25.841
39 12 0.183 0.716 1.552 2.626 3.866 5.202 6.575 7.939 9.261 10.521 11.705 12.807 13.827 14,766 15.628 16.418 17.141 17.802 18.407 18.961 22.543 24.208 25.072 26309 26.745
g 13 0.185 0.723 1.568 2.655 3.910 5.263 6.655 8.040 9.384 10.666 11.873 12.998 14.041 15.003 15.887 16.698 17.442 18.123 18.747 19320 23.049 24.809 25.735 27.070 27.542
> 1.4 0.186 0.729 1.582 2.678 3.945 5.312 6.720 8.122 9.484 10.785 12.011 13.155 14.217 15.198 16.101 16.931 17.692 18.391 19.032 19.621 23.480 25326 26308 27.441 28.249
O 1.5 0.188 0.734 1.592 2.697 3.973 5.352 6.773 8.189 9.566 10.883 12.124 13.285 14364 15.361 16280 17.125 17.902 18.616 19.272 19.875 23.850 25.772 26.808 28336 28.880
1.6 0.189 0.738 1.601 2.712 3.996 5.385 6.816 8.244 9.634 10.963 12219 13394 14.486 15.497 16.430 17.289 18.079 18.806 19.475 20.090 24.169 26.161 27245 28.866 29.445
1.7 0.189 0.741 1.608 1724 4.016 5.412 6.852 8.290 9.690 11.031 12.298 13.484 14.589 15.511 16.556 17.427 18.229 18.968 19.648 20274 24.444 26.501 27.629 29340 29.955
1.8 0.190 0.744 1.614 2.735 4.032 5.434 6.882 8328 9.737 11.087 12.364 13.561 14.675 15.7Q8 16.663 17.545 18357 19.105 19.795 20.431 24.684 26.799 27.969 29.765 30.416
1.9 0.191 0.746 1.619 2.743 4.045 ^.453 6.908 8.360 9.777 11.135 12.420 13.625 14.749 15.791 16.755 17.645 18.466 19.224 19.922 20.567 24.893 27.062 28.270 30.149 30.835
20 0.191 0.748 1.623 2.751 4.056 5.469 6.929 8387 9.811 11.175 12.468 13.680 14.811 15.861 16.833 17.731 18.560 19325 20031 20.684 25.077 27294 28.537 30.496 31217
3J0 0.193 0.756 1.642 2.785 4.109 5544 7.030 8.517 9.972 11.371 12.699 13.950 15.120 16211 17224 18.164 19.036 19.844 20.594 21.289 26.082 28.619 30.108 32.676 32.742
4.0 0.194 0.759 1.648 2.794 4;124 5566 7.058 8.540 10.018 11.427 11767 14.029 15.212 16.316 17343 18.298 19.185 20.008 20.772 21.483 26,439 29.128 30.745 33.687 35.064
5.0 0.194 0.760 1.650 2.798 4.129 5574 7.069 8568 10.036 11.449 12.793 14.060 15248 16357 17390 18.351 19.243 20.073 20.844 21562 26.592 29359 31.049 34232 35.872
10O 0.194 0.761 1.652 2.801 4.135 5581 7.080 8.582 10.053 11.470 12.818 14.095 15283 16398 17.436 18.403 19.302 20.138 20.917 21.641 26.758 29.624 31.419 35.049 37513
INF 0.194 0.761 1.652 2.802 4.136 5582 7.081 8584 10.056 11.473 12.822 14.095 15288 16.404 17.443 18.411 19.311 20,148 20.928 21.654 26.785 29.672 31.490 35.274 39.172
a
m
o
2
o
l/d^ 0.1
0.2
0.3
(1) (2)
(3)
(4)
^ Table 16 Percentage Sky Components on the Vertical Plane Parallel to a
Vertical Rectanduiar Opening for the Clear Design Sky
(Clause A- 1.5)
0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 3.0 4.0 5.0 10.0 INF
(5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25) (26)
0.1 0.728 1.429 2.078 2.600 3.167 3.660 3.964 4.265 4.513 4.717 4.883 5.020 5.132 5.225 5.301 5.365 5.418 5.463 5.501 5.533 5,687 5.733 5.749 5.765 5.766
0.2 1.429 2.803 4.007 5.221 6.220 7.073 7.790 8.385 8.876 9.278 9.609 9.880 10.103 10.286 10.439 10.565 10.671 10.760 10.835 10.899 11.207 11.296 11.330 11.362 11.365
0.3 2.068 4.061 5.913 7.580 9.040 10.285 11.337 12.212 12.934 13.528 14.016 14.417 14.747 15.020 15.246 15.434 15,591 15.724 15.836 15.931 16.390 16,523 16,574 16,623 16.627
0.4 2.529 4.970 7.249 9.312 11.133 12.707 14.042 15.164 16.097 16.870 17.507 18.025 18.458 18.816 19.113 19.360 19.568 19.742 19.890 20.015 20.624 20.801 20.868 20.933 20.939
0.5 2.852 5.608 8.186 10.529 12.606 14.401 15.952 17.256 18.350 19.262 20.021 20.652 21.177 21.613 21.978 22.275 22.530 22,746 22.923 23.082 23.836 24.056 24,140 24,222 24.229
0.6 3.086 6.070 8.867 11.415 13.681 15.656 17.353 18.793 20.008 21.027 21.879 22.592 23.189 23.689 24.109 24.462 24.761 25.014 25.229 25.412 26.229 26.561 26.662 26.759 26.768
0.7 3.259 6.413 9.373 12.074 14.482 16.588 18.402 19.949 21.257 22.359 23.285 24.063 24.716 25.267 25.731 26.124 26.458 26.742 26.984 27.192 28.214 28.517 28.634 28.748 28.758
0.8 3.389 6.672 9.755 12.573 15.090 17.296 19.201 20.830 22.212 23.380 24.365 25.195 25.895 26.486 26.987 27.412 27.775 28.084 28.350 28.578 29.720 30.065 30.198 30.327 30.339
0.9 3.489 6.869 10.046 12.955 15.556 17.840 19.817 21.511 22.952 24.173 25.206 26.078 26.816 27.441 27.972 28.424 28.810 29.141 29.426 29.672 30.927 31.303 31.451 31.596 31.610
1.0 3.565 7.024 10.272 13.250 15.917 18.263 20.297 22.043 23.531 24.795 25.866 26.773 27.542 28.196 28.572 29.226 29.633 29.982 30.283 30.544 31.889 32.302 32.467 32.627 32.643
1.1 3.625 7.139 10.447 13.481 16.200 18.594 20.674 22.462 23.989 25.288 26.391 27.326 28.121 28.798 29.375 29.869 30.293 30.658 30.973 31.246 32.670 33.117 33.297 33.473 33.49!
1.2 3.672 7.233 10.586 13.663 16.423 18.857 20.973 22.795 24.353 25.681 26.810 27.770 28.587 29.283 29.878 30.388 30.826 31.204 31.532 31.816 33.309 33.796 33.981 34.173 34.193
1.3 3.709 7.307 10.696 13.807 16.602 19.067 21.213 23.062 24.646 25.998 27.148 28.128 28.963 29.676 30.286 30.810 31.261 31.651 31.989 32.283 33.836 34.350 34.550 34.756 34.779
1.4 3.739 7.366 10.784 13.924 16.745 19.236 21.406 23.278 24.884 26.255 27.424 28.420 29.271 29.998 30.621 31.157 31.618 32.018 32.365 32.667 34.374 34.813 35.035 35.247 35.271
1.5 3.763 7.414 10.856 14.018 16.861 19.373 21.563 23.454 25.077 26.465 27.649 28.660 29.523 30.262 30.897 31.443 31.914 32.322 32.677 32.986 34.641 35.202 35.436 35.663 35.689
1.6 3.783 7453 10.914 14.095 16.956 19.485 21.692 23.599 25.236 26.638 27.835 28.857 29.732 30.482 31.226 31.680 32.160 32.575 32.937 33.253 34.950 35.532 35.776 36.017 36.046
1.7 3.799 7.485 10.962 14.158 17.034 19.578 21.798 23.718 25.368 26.781 27.989 29.022 29.906 30.665 31.317 31.879 32.366 32.888 33.156 33.477 35.211 35.812 36.067 36.321 36.352
O 1,8 3,812 7,512 11.002 14.211 17.099 19.655 21.886 23.817 25.478 26.900 28.118 29.160 30.052 30.818 31.477 32.046 32.539 32.967 33.340 33.666 35.435 36.052 36.316 36.584 36.617
^ 1.9 3.824 7.534 11,035 14.254 17.153 19.719 21.960 23.900 25.570 27.001 28.226 26.276 30.175 30.948 31.613 32.188 32.686 33.119 33.497 33.828 35.626 35.259 36.532 36.812 36.847
2.0 3,833 7,553 11,062 14,291 17.199 19.773 22.022 23.970 25.647 27.086 28.318 29.374 31.279 31.058 31.728 32.308 32.811 33.249 33.631 33.965 35.791 36.438 36.719 37.011 37.048
3.0 3.876 7.639 11.192 14.463 17.412 20.027 22.316 24.302 26.016 27.491 28.757 29.846 30.783 31.592 32.291 32.898 33.427 33.889 34.294 34.551 36.640 37.380 37.715 38.107 38.157
4.0 3.888 7.663 11.228 14,511 17,471 20,098 22,398 24.398 26.121 27.606 28.884 29.983 30.930 31.748 32.457 33.074 33.611 34.082 34.496 34.860 36.915 37.699 38.063 38.510 38.579
p 5.0 3.893 7.672 11.241 14.529 17.494 20.125 22.430 24.432 26.161 27.650 28.932 30.035 30.986 31.808 32.521 33.142 33.683 34.157 34.574 34.943 37.028 37.834 38.214 38.696 38.781
10.0 3.897 7681 11.254 14,546 17.515 20,150 22,459 24,466 26.199 27.693 28.978 30.085 31,041 31,867 32,584 33.208 33.753 34.231 34.652 35.024 37.144 37.978. 38.382 38.927 39.057
INF 3.898 7.682 11.256 44.548 17.518 20.154 22.464 24.471 26.205 27.699 28.985 30.093 3L049 31.876 32.593 33.218 33.764 34.243 34.664 35.037 37.162 38.003 38.411 38.978 39.172
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and 'accepted standards'
in the fulfillment of the requirements of the Code. The
latest version of a standard shall be adopted at the time
of enforcement of the Code. The standards listed may
be used by the Authority as a guide in conformance
with the requirements of the referred clauses in the
Code.
IS No. Title
(1) 7662 Recommendations for
(Part 1) : 1974 orientation of buildings: Part 1
Non-industrial buildings
Code of practice for interior
illumination: Part 1 General
requirements and
recommendations for building
interiors (first revision)
Guide for daylighting of
buildings (second revision)
Code of practice for daylighting
of factory buildings
(2) 3646
(Part 1) : 1992
(3) 2440 : 1975
(4) 6060: 1971
IS No.
Title
7942 : 1976
Code of practice for daylighting
of educational buildings
(5) 1944
Code of practice for lighting of
(Parts 1 & 2) :
public thoroughfares: Parts 1
1970
and 2 For main and secondary
roads (Group A and B) (first
revision)
2672 : 1966
Code of practice for library
lighting
4347 : 1967
Code of practice for hospital
lighting
6665 : 1972
Code of practice for industrial
lighting
10894 : 1984
Code of practice for lighting of
educational institutions
10947 : 1984
Code of practice for lighting for
ports and harbours
(6) 3362 : 1977
Code of practice for natural
ventilation of residential
buildings (first revision)
PART 8 BUILDING SERVICES — SECTION 1 LIGHTING AND VENTILATION
47
NATIONAL BUILDING CODE OF INDIA
PART 8 BUILDING SERVICES
Section 2 Electrical and Allied Installations
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY AND CONVENTIONAL SYMBOLS
3 GENERAL REQUIREMENTS
4 PLANNING OF ELECTRICAL INSTALLATIONS
5 DISTRIBUTION OF SUPPLY AND CABLING
6 WIRING
7 FITTINGS AND ACCESSORIES
8 EARTHING
9 INSPECTION AND TESTING OF INSTALLATION
10 TELECOMMUNICATION AND OTHER MISCELLANEOUS SERVICES
1 1 LIGHTNING PROTECTION OF BUILDINGS
ANNEX A DRAWING SYMBOLS FOR ELECTRICAL INSTALLATION
IN BUILDING
EXTRACTS FROM INDIAN ELECTRICITY RULES, 1956
AREA REQUIRED FOR TRANSFORMER ROOM AND
SUBSTATION FOR DIFFERENT CAPACITIES
ADDITIONAL AREA REQUIRED FOR GENERATOR IN
ELECTRIC SUBSTATION
FORM OF COMPLETION CERTIFICATE
ANNEX B
ANNEX C
ANNEX D
ANNEXE
LIST OF STANDARDS
5
5
9
9
16
28
36
39
43
48
49
56
58
63
63
64
65
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
This Section covers essential requirements for electrical and allied installations in buildings.
This Section was first published in 1970 and was subsequently revised in 1983. In the first revision, general
guidance for electrical wiring installation in industrial location where voltage supply normally exceeds 650 V
was included. This Section was also updated based on the existing version of the Indian Standards. The importance
of pre-planning and exchange of information among all concerned agencies from the earlier stages of building
work was emphasized.
As a result of experience gained in implementation of 1983 version of the Code and feedback received as well as
revision of some of the relevant standards based on which this Section was prepared, a need to revise this part
was felt. This revision has, therefore, been prepared to take care of these developments. The title of this Section
has been modified from the erstwhile 'electrical installations' to 'electrical and allied installations' to reflect the
provisions now being included on certain allied installations. The significant changes incorporated in this revision
include:
a) The risk assessment procedure for lightening has been thoroughly changed apart from some other changes
in the provision of lightning protection of building.
b) Some of the provisions of wiring have now been aligned with the latest practices.
c) Many existing definitions have been modified in line with current terminologies used at national and
international level. Some new definitions have been added.
d) Provisions on installation of distribution transformer inside the multi-storeyed building have been
incorporated.
e) Concept of energy conservation in lighting has been introduced.
f) Concept of various types of earthing in building installation has been incorporated
This Section has to be read together with Part 8 'Building Services, Section 1 Lighting and Ventilation' for
making provision for the desired levels of illumination as well as ventilation for different locations in different
occupancies. Utmost importance should be given in the installation of electrical wiring to prevent short circuiting
and the hazards associated therewith.
Notwithstanding the provisions given in this Section and the National Electrical Code, the provisions of the
Indian Electricity Act, 2003 and the Rules and Regulations framed thereunder have to be necessarily complied
with.
The information contained in this Section is largely based on the following Indian Standards/Special Publication:
IS 732 : 1989 Code of practice for electrical wiring installations (third revision)
IS 12032 Specification for graphical symbols for diagrams in the field of electrotechnology:
(Part 11): 1987 Part 1 1 Architectural and topographical installation plan and diagrams
IS 4648 : 1968 Guide for electrical layout in residential buildings
IS 2309 : 1989 Protection of building and allied structures against lightning — Code of practice (second
revision)
SP 30 : 1984 National Electrical Code, 1985
All standards, whether given herein above or cross-referred to in the main text of this Section, are subject to
revision. The parties to agreement based on this Section are encouraged to investigate the possibility of applying
the most recent editions of the standards.
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
NATIONAL BUILDING CODE OF INDIA
PART 8 BUILDING SERVICES
Section 2 Electrical and Allied Installations
1 SCOPE
This Section covers the essential requirements for
electrical installations in buildings to ensure efficient
use of electricity including safety from fire and shock.
This Section also includes general requirements
relating to lightning protection of buildings.
2 TERMINOLOGY AND CONVENTIONAL
SYMBOLS
2.1 For the purpose of this Section, the following
definitions shall apply.
2.1.1 Accessory — A device, other than current using
equipment, associated with such equipment or with the
wiring on an installation.
2.1.2 Apparatus — Electrical apparatus including all
machines, appliances and fittings in which conductors
are used or of which they form a part.
2.1.3 Appliance — An item of current using
equipment other than a luminaire or an independent
motor.
2.1.4 Bunched — Cables are said to be 'bunched'
when two or more are contained within a single
conduit, duct, ducting, or trunking or, if not enclosed,
are not separated from each other.
2.1.5 Cable — A length of single-insulated conductor
(solid or stranded), or two or more such conductors,
each provided with its own insulation, which are laid
up together. The insulated conductor or conductors
may or may not be provided with an overall mechanical
protective covering.
2.1.6 Cable, Armoured — A cable provided with a
wrapping of metal (usually in the form of tape or wire)
serving as a mechanical protection.
2.1.7 Cable, Flexible — A cable containing one or
more cores, each formed of a group of wires, the
diameters of the cores and of the wires being sufficiently
small to afford flexibility.
2.1.8 Cable, Metal-Sheathed
with a metal sheath.
An insulated cable
2.1.9 Cable, PVC Sheathed-Insulated — A cable
in which the insulation of the conductor is a
poly vinylchloride (PVC) compound; with PVC sheath
also providing mechanical protection to the conductor
core or cores in the cable.
that when installed in uncovered locations, it will
withstand all kinds of weather variations (see 2.1.80,
for definition of Weatherproofing).
2.1.11 Cable, XLPE — A cable in which the insulation
of the conductor is cross-linked polythene and the
mechanical protection is provided for the core or cores
by a sheath of a poly vinyl chloride compound.
2.1.12 Ceiling Rose — A fitting (usually used to attach
to the ceiling) designed for the connection between
the electrical installation wiring and a flexible cord
(which is in turn connected to a lampholder).
2.1.13 Circuit — An assembly of electrical equipment
supplied from the same origin and protected against
overcurrent by the same protective device(s). Certain
types of circuit are categorized as follows:
a) Category 1 Circuit — A circuit (other than a
fire alarm or emergency lighting circuit)
operating at low voltage and supplied directly
from a mains supply system.
b) Category 2 Circuit — With the exception of
fire alarm and emergency lighting circuits,
any circuit for telecommunication (for
example, radio, telephone, sound distribution,
intruder alarm, bell and call and data
transmission circuits) which is supplied from
a safety source.
c) Category 3 Circuit — A fire alarm circuit or
an emergency lighting circuit.
2.1.14 Circuit Breaker — A mechanical switching
device capable of making, carrying and breaking
currents under normal circuit conditions and also of
making, carrying for a specified time, and breaking
currents under specified abnormal circuit conditions
such as those of short circuit.
NOTE — A circuit breaker is usually intended to operate in
frequently, although some types are suitable for frequent
operation.
2.1.15 Circuit, Final Sub — An outgoing circuit
connected to one-way distribution board and intended
to supply electrical energy at one or more points to
current, using appliances without the intervention of a
further distribution board other than a one-way board.
It includes all branches and extensions derived from
that particular way in the board.
2.1.16 Cleat — An insulated incombustible support
normally used for insulated cable.
2.1.10 Cable, Weatherproof^ A cable so constructed 2.1.17 Conductor, Aerial — Any conductor which is
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
supported by insulators above the ground and is
directly exposed to the weather.
NOTE — Four classes of aerial conductors are recognized:
a) Bare aerial conductors,
b) Covered aerial conductors,
c) Insulated aerial conductors, and
d) Weatherproof neutral- screened cable.
2.1.18 Conductor, Bare — A conductor not covered
with insulating material.
2.1.19 Conductor, Earthed — A conductor with no
provision for its insulation from earth.
2.1.20 Conductor, Insulated — A conductor
adequately covered with insulating material of such
quality and thickness as to prevent danger.
2.1.21 Conductor of a Cable or Core — The
conducting portion consisting of a single wire or group
of wires, assembled together and in contact with each
other or connected in parallel.
2.1.22 Connector — The part of a cable coupler or of
an appliance coupler which is provided with female
contact and is intended to be attached to the flexible
cable connected to the supply.
2.1.23 Connector Box or Joint Box — A box forming
a part of wiring installation, provided to contain joints
in the conductors of cables of the installations.
2.1.24 Connector for Portable Appliances — A
combination of a plug and socket arranged for
attachment to a portable electrical appliance or to a
flexible cord.
2.1.25 Consumer's Terminals — The ends of the
electrical conductors situated upon any consumer's
premises and belonging to him at which the supply of
energy is delivered from the service line.
2.1.26 Cord, Flexible — A flexible cable having
conductor of small cross-sectional area. Two flexible
cords twisted together are known as twin 'flexible
cord' .
2.1.27 Core of a Cable — A single conductor of a
cable with its insulation but not including any
mechanical protective covering.
2.1.28 Cut-out — Any appliance for automatically
interrupting the transmission of energy through any
conductor when the current rises above a pre-
determined amount.
2.1.29 Damp Situation — A situation in which
moisture is either permanently present or intermittently
present to such an extent as to be likely to impair the
effectiveness of an installation conforming to the
requirements for ordinary situations.
2.1.30 Dead — A portion of the circuit (normally
expected to carry a voltage) at or near about earth
potential or apparently disconnected from any live
system.
2.1.31 Direct Earthing System — A system of earthing
in which the parts of an installation are so earthed as
specified but are not connected within the installation
to the neutral conductor of the supply system or to earth
through the trip coil of an earth leakage circuit-breaker.
2.1.32 Distance Area or Resistance Area (for Earth
Electrode only) — The area of ground (around an earth
electrode) within which a voltage gradient measurable
with ordinary commercial instruments exists when the
electrode is being tested.
2.1.33 Discrimination (Over-Current Discrimination)
— Co-ordination of the operating characteristics of two
or more over-current protective devices such that, on
the incidence of over-currents within stated limits, the
device intended to operate within these limits does so,
while the others do not.
NOTES
1 Protective devices should have discrimination so that only
the affected part (minimum section) of the circuit is isolated,
even though a number of protective devices may be in the path
of the over current.
2 Distinction is made between series discrimination involving
different over-current protective devices passing substancially
the same over-current and network discrimination involving
identical protective devices passing different proportions of
the over-current.
2.1.34 Earth — The conductive mass of the earth,
whose electric potential at any point is conventionally
taken as zero.
2.1.35 Earth Continuity Conductor — The conductor,
including any clamp, connecting to the earthing lead
or to each other those parts of an installation which
are required to be earthed. It may be in whole or in
part the metal conduit or the metal sheath or armour of
the cables, or the special continuity conductor of a cable
or flexible cord incorporating such a conductor.
2.1.36 Earth Electrode — A conductor or group of
conductors in intimate contact with and providing an
electrical connection to earth.
2.1.37 Earth Fault — Accidental connections of a
conductor to earth when the impedance is negligible,
the connection is called a dead earth.
2.1.38 Earthing Lead — The final conductor by which
the connection to the earth electrode is made.
2.1.39 Earth Leakage Circuit Breaker System — A
system of earthing in which the parts of an installation,
specified, to be earthed are so earthed through one or
more earth leakage circuit-breakers or relays.
NATIONAL BUILDING CODE OF INDIA
2.1.40 Enclosed Distribution Board — An enclosure
containing bus bars with one or more control and
protected devices for the purpose of protecting,
controlling or connecting more than one outgoing
circuits fed from one or more incoming circuits,
2.1.41 Exposed Metal — All metal parts of an
installation which are easily accessible other than:
a) parts separated from live parts by double
insulation;
b) metal name-plates, screw heads, covers, or
plates, which are supported on or attached or
connected to substantial non-conducting
material only in such a manner that they do
not become alive in the event of failure of
insulation of live parts and whose means of
fixing do not come in contact with any internal
metal; and
c) parts which are separated from live parts by
other metal parts which are themselves
earthed or have double insulation.
2.1.42 Fire Survival Cable — A cable which continues
in service after exposure to a temperature of 900°C
for 20 min or 700°C for 90 min.
2.1.43 Fitting, Lighting — A device for supporting or
containing a lamp or lamps (for example, fluorescent
or incandescent) together with any holder, shade, or
reflector, for example, a bracket, a pendant with ceiling
rose, an electrolier, or a portable unit.
2.1.44 Flameproof Enclosure — An enclosure which
will withstand without injury any explosion of
inflammable gas that may occur within it under
practical conditions of operation within the rating of
the apparatus (and recognized overloads, if any,
associated therewith) and will prevent the transmission
of flame which may ignite any inflammable gas that
may be present in the surrounding atmosphere.
NOTES
1 Hazardous areas are classified into different zones, depending
upon the extent to which an explosive atmosphere could exist
at that place. In such areas flame proof switchgear, fittings,
accessories, have to be used/installed in flameproof enclosure.
2 An electrical apparatus is not considered as flameproof
unless it complies with the appropriate statutory regulations.
3 Other types of fittings are also in vogue in wiring
installations, for example, 'increased safety' .
2.1.45 Flame Retardant Cable — Flame retardant
cable with reduced halogen evaluation and smoke.
2.1.46 Fuse — A device that, by the fusion of one or
more of its specially designed and proportioned
components, opens the circuit in which it is inserted
when the current through it exceeds a given value for
a sufficient time. The fuse comprises all the parts that
form the complete device.
2.1.47 Fuse-Element — A part of the fuse-link
designed to melt under the action of current
exceeding some definite value for a definite period of
time.
2.1.48 Harmonics (Current and Voltage) — All
alternating current which is not absolutely sinusoidal
is made up of a fundamental and a certain number
of current harmonics which are the cause of its
deformation (distortion) when compared to the
theoretical sine-wave.
2.1.49 Inflammable — A material capable of being
easily ignited.
2.1.50 Installation (Electrical), of Buildings — An
assembly of associated electrical equipment to fulfil a
specific purpose or purposes and having coordinated
characteristics.
2.1.51 Insulated — Insulated shall mean separated
from adjacent conducting material or protected from
personal contact by a non-conducting substance or an
air space, in either case offering permanently sufficient
resistance to the passage of current or to disruptive
discharges through or over the surface of the substance
or space, to obviate danger or shock or injurious
leakage of current.
2.1.52 Insulation, Basic — Insulation applied to live
parts to provide basic protection against electric shock.
NOTE — Basic insulation does not necessarily include
insulation used exclusively for functional purposes.
2.1.53 Insulation, Double — Insulation comprising
both basic and supplementary insulation.
2.1.54 Insulation (Electrical) — Suitable non-
conducting material, enclosing, surrounding or
supporting a conductor.
2.1.55 Insulation, Reinforced — Single insulation
applied to live parts, which provides a degree of
protection against electric shock equivalent to double
insulation under the conditions specified in the relevant
standard.
NOTE — The term 'single insulation' does not imply that the
insulation must be one homogeneous piece, It may comprise
several layers which cannot be tested singly as supplementary
or basic insulation.
2.1.56 Insulation, Supplementary — Independent
insulation applied in addition to basic insulation in
order to provide protection against electric shock in
the event of a failure of basic insulation.
2.1.57 Linked Switch — Switches linked together
mechanically so as to operate simultaneously or in
definite sequence,
2.1.58 Live or Alive — Electrically charged so as to
have a potential different from that of earth.
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
2.1.59 Locations, Industrial — Locations where tools
and machinery requiring electrical wiring are installed
for manufacture or repair.
2.1.60 Locations, Non-Industrial — Locations other
than industrial locations, and shall include residences,
offices, shops, showrooms, stores and similar premises
requiring electrical wiring for lighting, or similar
purposes.
2.1.61 Miniature Circuit Breaker — Mechanical
switching device capable of making, carrying and
breaking currents under normal circuit conditions and
also making carrying currents for specified times and
automatically breaking currents under specified
abnormal circuit conditions such as those of overload
and short circuits.
2.1.62 Multiple Earthed Neutral System — A system
of earthing in which the parts of an installation
specified to be earthed are connected to the general
mass of earth and, in addition, are connected within
the installation to the neutral conductor of the supply
system.
2.1.63 Neutral Conductor — Includes the neutral
conductor of a three-phase four-wire system, the
conductor of a single-phase or dc installation which is
earthed by the supply undertaking (or otherwise at the
source of the supply), and the middle wire or common
return conductor of a three- wire dc or single-phase ac
system.
2.1.64 Plug — A device, provided with contact pins,
which is intended to be attached to a flexible cable,
and which can be engaged with a socket outlet or with
a connector.
2.1.65 Point (in Wiring) — A termination of the fixed
wiring intended for the connection of current using
equipment.
2.1.66 Residual Current Circuit Breaker — A
mechanical switching device design to make, carry and
break currents under normal service conditions and to
cause the opening of the contacts when the residual
currents attains a giving value under specified
conditions.
2.1.67 Service — The conductors and equipment
required for delivering energy from the electric supply
system to the wiring system of the premises served.
2.1.68 Socket-Outlet — Accessory having socket
contacts designed to engage with the pins of a plug
and having terminals for the connection of cable(s).
NOTE — A luminaire track system is not regarded as a socket-
outlet system.
2.1.69 Switch — A mechanical switching device
capable of making, carrying and breaking current under
normal circuit conditions, which may include specified
operating overload conditions, and also of carrying for
a specified time currents under specified abnormal
circuit conditions such as those of short circuit.
NOTE — A switch may also be capable of making, but not
breaking, short-circuit currents.
2.1.70 Switchboard — An assembly of switchgear
with or without instruments, but the term does not apply
to a group of local switches in a final circuit.
NOTE — The term 'switchboard* includes a distribution board.
2.1.71 Switch Disconnectors — A device used to open
(or close) a circuit when either negligible current is
interrupted (or established) or when the significant
change in the voltage across the terminals of each of
the pole of the disconnectors occurs; in the open
position it provides an isolating distance between the
terminals of each pole.
2.1.72 Switch Disconnector Fuse — A composite unit,
comprising a switch with the fuse contained in or
mounted on the moving member of the switch.
2.1.73 Switchgear — A general term covering
switching devices and their combination with
associated control, measuring, protective and
regulating equipment, also assemblies of such devices
and equipment with associated interconnections,
accessories, enclosures and supporting structures,
intended in principle for use in connection with
generation, transmission, distribution and conversion
of electric energy.
2.1.74 Usable Wall Space — All portions of a wall,
except that occupied by a door in its normal open
position, or occupied by a fire place opening, but
excluding wall spaces which are less than 1 m in extent
measured along the wall at the floor line.
2.1.75 Voltage, Extra Low (ELV) — The voltage
which does not normally exceed 50 V.
2.1.76 Voltage, Low (LV) — The voltage which
normally exceed 50 V but does not normally exceed
250 V.
2.1.77 Voltage, Medium {MV) — The voltage which
normally exceeds 250 V but does not exceed 650 V.
2.1.78 Voltage, High (HT, HV) — The voltage which
normally exceeds 650 V but less than or equal to 33 kV.
2.1.79 Voltage, Extra High (EHT) — The voltage,
which normally exceeds 33 kV.
2.1.80 Weatherproof — Accessories, lighting fittings,
current-using appliances and cables are said to be of the
weatherproof type, if they are so constructed that when
installed in open situation they will withstand the effects
of rain, snow, dust and temperature variations.
8
NATIONAL BUILDING CODE OF INDIA
For definition of other terms reference may be made
to accepted standards [8-2(1)].
2.2 Conventional Symbols
The architectural symbols that are to be used in all
drawings, wiring plans, etc, for electrical installations
in buildings shall be as given in Annex A.
For other graphical symbols used in electrotechnology,
reference may be made to good practice [8-2(1)].
3 GENERAL REQUIREMENTS
3.1 Conformity with Electricity Act, 2003 and Rules
Amended Up-to-date
The installation shall generally be carried out in
conformity with the requirements of The Electricity
Act, 2003 as amended up-to-date and the Indian
Electricity Rules, 1956 framed thereunder and also the
relevant regulations of the Electric Supply Authority
concerned as amended from time to time. Extracts from
the Indian Electricity Rules, 1956, referred to in this
section, are given in Annex B.
NOTE — Indian Electricity Rules which are being revised
would become applicable on their notification.
3.2 Materials
All materials, fittings, appliances, etc, used in electrical
and allied installations, shall conform to Part 5 'Building
Materials' and other related Indian Standards.
3.3 Coordination with Local Supply Authority
a) In all cases, that is, whether the proposed
electrical work is a new installation or
extension of an existing one, or a modification
involving major changes, the electricity
supply undertaking shall be consulted about
the feasibility, etc, at an early date.
b) Addition to an Installation — An addition,
temporary or permanent, shall not be made
to the authorized load of an existing
installation, until it has been definitely
ascertained that the current carrying capacity
and the condition of existing accessories,
conductors, switches, etc, affected, including
those of the supply authority are adequate for
the increased load. The size of the cable/
conductor shall be suitably selected on the
basis of the ratings of the protective devices.
Ratings of protective devices and their types
shall be based on the installed load, switching
characteristics and power factor.
Load assessment and application of suitable diversity
factor to estimate the full load current shall be made
as a first step. This should be done for every circuit,
submain and feeder. Power factor and efficiency of
loads shall also be considered. Diversity factor assumed
shall be based on one's own experience. Allowance
should be made for about 15 percent to 20 percent for
extension in near future and the design circuit is
calculated for each circuit and submain. The wiring
system to be adopted should also be decided in
accordance with the environmental requirements. The
sizes of wiring cables are decided not merely to carry
the load currents, but also to withstand thermal effects
of likely over currents and also ensure acceptance level
of voltage drop.
3.4 Power Factor Improvement in Consumers'
Installation
3.4.1 Conditions of supply of electricity boards or
licensees stipulate the lower-limit of power factor
which is generally 0.85.
3.4.2 Principal causes of low power factor are many.
For guidance to the consumers of electric energy who
take supply at low and medium voltages for
improvement of power factor, reference shall be made
in accordance with good practice [8-2(2)].
3.5 Execution of Work
Unless otherwise exempted under the appropriate rule
of the Indian Electricity Rules, the work of electrical
installations shall be carried out by a licensed electrical
contractor and under the direct supervision of a person
holding a certificate of competency and by persons
holding a valid permit issued and recognized by any
State government.
3.6 Safety procedures and practices shall be kept in
view during execution of the work in accordance with •
good practice [8-2(4)].
3.7 Safety provisions given in Part 4 'Fire and Life
Safety' shall be followed.
4 PLANNING OF ELECTRICAL
INSTALLATIONS
4.1 General
The design and planning of an electrical wiring
installation involve consideration of all prevailing
conditions, and is usually influenced by the type and
requirement of the consumer. A competent electrical
design engineer should be involved at the planning
stage with a view to providing for an installation that
will prove adequate for its intended purpose, and safe
and efficient in its use. The information given in 3 shall
also be kept in view.
4.1.1 The design and planning of an electrical wiring
installation shall take into consideration, some or all
of the following:
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
a) the type of supply, occupancy, envisaged load
and the earthing arrangement available;
b) the atmospheric condition, such as cooling
air temperature, moisture or such other
conditions which are likely to affect the
installation adversely;
c) the possible presence of inflammable or
explosive dust, vapour or gas;
d) the degree of electrical and mechanical
protection necessary;
e) the importance of continuity of service
including the possible need for standby
supply;
f) the probability of need for modification or
future extension;
g) the probable operation and maintenance cost
taking into account the electricity supply
tariffs available;
h) the relative cost of various alternative
methods;
j) the need for radio and telecommunication
interference suppression;
k) case of maintenance;
m) safety aspects;
n) energy conservation; and
p) the importance of proper discrimination
between protective devices for continuity of
supply and limited isolation of only the
affected portion.
4.1.2 All electrical apparatus shall be suitable for the
services these are intended for,
4.1.3 Co-ordination
Proper co-ordination and collaboration between the
architect, civil engineer and the electrical and mechanical
engineer shall be effected from the planning stage of
the installation. The provisions that will be needed for
the accommodation of substation, transformer,
switchrooms, service cable ducts, rising mains and
distribution cables, sub-distribution boards, openings
and chases in floors and walls for all required electrical
installations, etc, shall be specified in advance.
4.1.4 Before starting wiring and installation of fittings
and accessories, information should be exchanged
between the owner of the building/architect/electrical
contractor and the local supply authority in respect of
tariffs applicable, types of apparatus that may be
connected under each tariff, requirement of space for
installing meters, switches, etc, and for total load
requirements of lights, fans and power.
4.1.5 While planning an installation, consideration
should be taken of the anticipated increase in the use
of electricity for lighting, general purpose socket-
outlet, kitchen heating, etc.
It is essential that adequate provision should be made
for all the services which may be required immediately
and during the intended useful life of the building, for
the householder may otherwise be tempted to carry
out extension of the installation himself or to rely upon
use of multiplug adopters and long flexible cords, both
of which are not recommended.
4.2 Location and Requirement of Substation
Information on location and requirements of a
substation should cover the following:
4.2.1 Location
a) The substation should preferably be located
in separate building and could be adjacent to
the generator room, if any. Location of
substation in the basement floors should be
avoided, as far as possible.
b) The ideal location for an electrical substation
for a group of buildings would be at the
electrical load centre on the ground floor.
c) The floor level of the substation or switch
room shall be above the highest flood level
of the locality.
d) Generally the load centre would be
somewhere between the geometrical centre
and the air conditioning plant room, as air
conditioning plant room would normally be
the largest chunk of load, if the building is air
conditioned.
e) Substations with oil filled equipment will
require great consideration for the fire
detection, protection and suppression. Oil
cooled transformers require a suitable soak
pit with gravity flow to contain the oil in the
event of the possibility of oil spillage from
the transformer on its failure. Substations with
oil filled equipment shall not be located in
any floor other than the ground floor or a
semi-basement. Such substations with high oil
content may be housed in a separate service
building or a substation building, which is not
the part of a multi-storeyed building.
f) In case electric substation has to be located
within the main multi-storeyed building itself
for unavoidable reasons, then it should be
located on the floor close to ground level, but
shall have direct access from the street for
operation of the equipments. The provision
for installation and removal of substation
equipments may be provided from inside the
building.
10
NATIONAL BUILDING CODE OF INDIA
g) Substations located within a multi-storeyed
building shall not have oil filled transformers,
even if it is at the ground level (see Part 4
'Fire and Life Safety'). Substations with very
little combustible material, such as a Dry type
transformer, with Vaccum (or SF 6 ) HT
switchgear and ACB or MCCB for MV can
be located in the basement as well as upper
floors in a building with high load density in
the upper floors. (Some functional buildings
such as hospitals, air traffic control towers,
computer centres are likely to have high
loading in a few upper floors and in such
cases, it may be preferable to provide oil-free
substations at upper levels. This measure will
decrease the current flow at various points,
thereby contributing to reduction of
vulnerability to fire),
h) The power supply control to any such
substation or transformer (located at basement
levels or upper floors) shall be from a location
on ground floor/first basement level having
direct access from outside so that in case of
fire, the electrical supply can be easily
disconnected,
j) Oil filled transformers may be used only in
substations located in separate single or two
storeyed service buildings outside the main
building structure and there shall atleast
6 meter clear distance between the adjoining
buildings and substation such that fire tender
is able to pass between the two structures,
k) If dry type transformer is used, it may
be located adjacent to medium voltage
switchgear in the form of unit type substation.
No separate room or fire barrier for the
transformer is required, in a substation with
oil free equipment. In such a case the room
size will decrease. Layout of equipment has
to keep the requirement that any one piece of
equipment or sub-assembly can be taken out
of service and out of the installed location,
while keeping the remaining system in
service,
m) The emergency power supply (such as
Generating Sets) should not be allowed to be
installed above ground floor or below first
basement level of building. There shall be
provision of separate direct escape and entry
into these areas from outside so that in case
of fire, electrical supplies can be disconnected
to avoid additional losses which may be
caused due to electrical supply, present at the
time of fire,
n) For transformers having large oil content
(more than 2 000 litres), Rule 64 of Indian
Electricity Rules, 1956 as amended time to
time shall apply.
p) Facility for connection from substation
to adjoining building to feed essential
emergency load in that building, such as
escape route lighting, fire or sprinkler pumps,
emergency communication systems shall be
provided. Similarly, the essential emergency
load switchboard of this building or building
complex should be so as to be capable of
receiving power for such loads from the
adjoining building or building complex, with
its own substation/DG sets shut off due to
crisis conditions such as fire.
q) The availability of power lines nearby may
also be kept in view while deciding the
location of the substation.
r) For detailed information regarding location
of transformers reference may be made to
good practice [8-2(3)].
s) All door openings from substation, electrical
rooms, etc should open towards outside.
t) For acoustical enclosures/treatment reference
may be made to Part 8 'Building Services,
Section 4 Acoustics, Sound Insulation and
Noise Control'.
4.2.2 Type of Building for Substations
The substations enclosure, that is, walls, floor, ceiling,
openings, doors, etc shall have 2 hour fire rating (see
Part 4 Tire and Life Safety').
4.2.3 Layout of Substation
In allocating the area of substation, it is to be noted
that the flow of electric power is from supply
company's room to HV room, then to transformer and
finally to the medium voltage switchgear room. The
layout of the room shall be in accordance with this
flow, so as to optimise the cables, bus-trunking etc,
Visibility of equipment controlled from the operating
point of the controlling switchgear is also a desirable
feature, though it may not be achievable in case of
large substations.
4.2.4 Room/Spaces Required
Generally the following rooms/spaces are required in
a substation:
a) Supply company's switchgear room and/or
space for meters.
b) Capacity and Size — The capacity of a
substation depends upon the area of the
building and its type. The capacity of
substation may be determined based on the
following load requirements:
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
11
Table of Typical Allowances for Diversity
Purpose of Final Circuit Individual Household
Fed from Conductors or Installations, including
Switchgear to which
Diversity Applies
(1)
Individual Dwelling
of a Block
(2)
Type of Premises
Small, Shops, Stores
Offices and Business
Premises
(3)
Type of Premises Small
Hotels, Boarding
Houses etc,
(4)
Lighting
Heating and power
66% of total demand
Cooking appliances
of total current
demand upto 10 A
+40% of any current
demand in excess of
10A
10A
+30% full load of
connected cooking
appliances in excess of
10 A + 5 A if socket-
outlet incorporated in
unit.
Motors (other than lift
motors which are subject
to special consideration)
Water heater
80% full load of largest
appliance
+50% of second largest
appliance
+25% full load of
remaining appliances
warming 50%
thermal 50%
heating
Floor
installations
Water heaters
storage space
installations
Standard arrangements of 80% of current demand
final circuits in of largest circuit
accordance with IS 732 +40% of current demand
of every other circuit
Socket outlets other than
those included above and
stationary equipment
other than those listed
above
NOTES
80% of current demand
of largest point of +40%
of current demand of
every other point of.
of total current
demand
80% full load of largest
appliance
+60% of remaining
appliances
80% full load of largest
appliance
+60% full load of
second largest appliance
+50% full load of
remaining appliances
80% full load of largest
motor
+60% full load of
second largest motor
+50% full load of
remaining motors
80% full load of largest
appliance
+60% of second largest
appliance
+25% full load of
remaining appliances
75% of total current
demand
80% full load of largest
appliance
+60% of second largest
appliances
+40% of remaining
appliances
80% of largest appliance
+60% of full load of
second largest appliance
+50% full load of
remaining appliances
80% full load of largest
motor
+50% full load of
remaining motors
80% full load of largest
appliance
+60% of second largest
appliance
+25% full load of
remaining appliances
of current demand
of largest circuit
+50% of current demand
of every other circuit
80% of current demand 80% of current demand of
of largest point of
+60% of current
demand of every other
point of
largest point of +60% of
current demand of every
point in main rooms
(dinning rooms, etc) +40%
of current demand of every
other point of.
1 For the purpose of the table an instantaneous water heater is deemed to be a water heater of any loading which heats water only
while the tap is turned on and therefore uses electricity intermittently.
2 It is important to ensure that the distribution boards are of sufficient rating to take the total load connected to them without the
application of any diversity.
12
NATIONAL BUILDING CODE OF INDIA
After calculating the electrical load on the
above basis, a load factor of 70-90 percent is
to be applied to arrive at the minimum
capacity of substation. The area required for
substation and transformer room for different
capacities is given in Annex C for general
guidance. For reliability, it would be
necessary to split the load into more than one
transformer and also provide for standby
transformer as well as multiple sources, bus-
section, etc.
c) High Voltage Switch Room — In case of
substation having one transformer and one
source of supply, the owner is required to
provide one high voltage switch. In case
of single point supply with two or more
transformers the number of switch required
will be one for incoming supply and one for
each transformer. In case of duplicate supply
two switches shall be provided with
mechanical/electrical in locking arrangement
where necessary in cables with switches. In
case the number of incoming and outgoing
switches exceed five, bus coupler of suitable
capacity should invariably be provided.
The floor area required in case of a single
switch is roughly 4 m x 4 m and for every
additional switch the length would be
increased by 1 m.
d) Facility for connection from substation of
adjoining building to feed emergency loads
shall be permitted for feeding escape route
and signage lighting as well as selected
section of the fire protection system. Similarly
on a reciprocal basis facility to feed the
adjoining building for such emergency loads
may be provided by necessary switchgear,
e) Medium Voltage Switch Room — The floor
area required in respect of medium voltage
switchgear room may be determined keeping
in view the number and type of incoming/
outgoing bus coupler switches including
likely expansion in future.
f) Room for Standby Generator — It is preferable
to install the standby generator in service
building. If installed in main building it shall
be at the ground floor or at the semi basement,
alternatively, in the first basement with
facilities for forced ventilation. Adequate
space shall be provided for storing of fuel.
Compartmentation for fire protection with
detection and first-aid protection measures is
essential. Different type of requirements exist
for the diesel engine and generator for the oil
storage area and for the switchgear.
g) Facilities including space at appropriate
positions, relative to the location of the
installed equipment has to be kept in the
layout design for removal of equipment or
sub-assemblies for repair or maintenance.
When it is located, other than the ground level
with direct equipment access, a hatch or ramp
shall be required.
h) Other environmental requirements under the
provisions of Environment Protection Rules,
1986 as amended time-to-time shall be taken
into account from the aspect of engine
emissions including regarding the height of
exhaust pipe and permitted noise levels/noise
control.
j) The capacity of standby generating set shall
be chosen on the basis of essential light load,
essential air conditioning load, essential
equipment load and essential services load,
such as one lift out of the bank of lifts, one or
all water pumps, etc. Having chosen the
capacity and number of generating sets,
required space may be provided for their
installation (see Annex D for general
guidance).
k) The generating set should preferably be
housed adjacent to MV switchgear in the
substation building to enable transfer of
electrical load quickly as well as to avoid
transfer of vibration and noise to the main
building. Acoustics lining of the room shall
be in line with the requirements of Central
Pollution Control Board (CPCB). If DG Set
is located outdoor, it shall be housed in
acoustics enclosure. The generator house
should have proper ventilation, fire fighting
equipment, etc (see also 4.2.2).
m) Requirements of Room
1) The areas given above in respect of the
different categories of rooms holds good
if they are provided with windows and
independent access doors in accordance
with local regulations.
2) All the rooms shall be provided with
partitions up to the ceiling and shall have
proper ventilation. Special care should
be taken to ventilate the transformer
rooms and where necessary louvers at
lower level and exhaust fans at higher
level shall be provided at suitable
locations.
3) In order to prevent storm water entering
the transformer and switch rooms
through the soak-pits, the floor level, the
substation shall be at least 15 cm above
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
13
the highest flood water level that may be
anticipated in the locality. Also, facility
shall be provided for automatic removal
of water.
4) The minimum height of high voltage
switchgear room shall be 3.6 mbelowthe
soffit of the beam.
n) Fire Compartmentation — It is advisable to
provide fire compartmentation of buildings
and segregation of associated wiring. Busbar
trunking of horizontal and vertical distribution
type in place of cable based distribution
system shall be used.
4.3 Location of Switch Room
In large installations other than where a substation is
provided, a separate switch room shall be provided;
this shall be located as closely as possible to the
electrical load centre preferably near the entrance of
the building on the ground floor or on the first
basement level, and suitable ducts shall be laid with
minimum number of bends from the points of entry
of the main supply cable to the position of the main
switchgear. The switch room shall also be placed in
such a position that rising ducts may readily be
provided therefrom to the upper floors of the building
in one straight vertical run. In larger buildings, more
than one rising duct may be required and then
horizontal ducts may also be required for running
cables from the switch room to the foot of each rising
main. Such cable ducts shall be either be reserved for
the electrical services only or provided with a means
of segregation for medium and low voltage
installations, such as call-bell systems; telephone
installations, fire detection and alarm system,
announcemeni or public address system. Cables for
essential emergency services such as those related to
fire detection, alarm, announcement should use either
metal conduit in addition to physical segregation from
power cables or use fire survival cables, so that the
service is maintained even in the event of a fire at
least for a period of about 20 min.
4.4 Location and Requirements of Distribution
Panels
The electrical control gear distribution panels and other
apparatus, which are required on each floor may
conveniently be mounted adjacent to the rising mains,
and adequate space should be provided at each floor
for this purpose.
4.5 Substation Safety
The owner or the operator of any substation shall be
collectively and severally be responsible for any lapse
or neglect leading to an accident or an incidence of an
avoidable abnormality and shall take care of the safety
requirements as follows:
a) enclose the substation where necessary to
prevent, so far as is reasonably practicable,
danger or unauthorised access;
b) enclose any part of the substation, which is
open to the air and contains live equipment
which is not encased, with a fence or wall not
less than 2.4 m in height to prevent, so far
as is reasonably practicable, danger or
unauthorised access;
c) ensure that, so far as is reasonably practicable,
there are at all times displayed:
1) sufficient safety signs of such size and
placed in such positions as are necessary
to give due warning of such danger as
is reasonably foreseeable in the
circumstances;
2) a notice which is placed in a conspicuous
position and which gives the location or
identification of the substation, the name
of each generator or distributor who owns
or operates the substation equipment
making up the substation and the
telephone number where a suitably
qualified person appointed for this
purpose by the generator or distributor
will be in constant attendance; and
3) such other signs, which are of such size
and placed in such positions, as are
necessary to give due warning of danger
having regard to the siting of, the nature
of, and the measures taken to ensure the
physical security of, the substation
equipment; and
d) take all reasonable precautions to minimize
the risk of fire associated with the equipment,
4.6 Overhead Lines, Wires and Cables
4.6.1 Height Requirement
While overhead lines may not be relevant within
buildings, regulations related to overhead lines are of
concern from two different angles.
a) Overhead lines may be required in building
complexes, though use of underground cables
is the preferred alternative.
b) Overhead lines may be passing through the
site of a building. In such a case the safety
aspects are important for the construction
activity in the vicinity of the overhead line as
well as portions of low height buildings that
may have to be constructed below the
overhead lines.
14
NATIONAL BUILDING CODE OF INDIA
For minimum distance (vertical and
horizontal) of electric lines/wires/cables from
buildings, reference may be made to Part 3
'Development Control Rules and General
Building Requirements'.
c) Any person responsible for erecting
an overhead line will keep informed the
authority(s) responsible for services in that
area for telecommunication, gas distribution,
water and sewage network, roads so as to have
proper co-ordination to ensure safety. He
shall also publish the testing, energising
programme for the line in the interests of
safety.
4.6.2 Position, Insulation and Protection of Overhead
Lines
Any part of an overhead line which is not connected
with earth and which is not ordinarily accessible shall
be supported on insulators or surrounded by
insulation.
Any part of an overhead line which is not connected
with earth and which is ordinarily accessible shall
be:
a) made dead; or
b) so insulated that it is protected, so far it is
reasonably practicable, against mechanical
damage or interference; or
c) adequately protected to prevent danger.
Any person responsible for erecting a building or
structure which will cause any part of an overhead line
which is not connected with earth to become ordinarily
accessible shall give reasonable notice to the generator
or distributor who owns or operates the overhead line
of his intention to erect that building or structure.
Any bare conductor not connected with earth, which
is part of a low voltage overhead line, shall be situated
throughout its length directly above a bare conductor
which is connected with earth.
No overhead line shall, so far as is reasonably
practicable, come so close to any building, tree or
structure as to cause danger.
In this regulation the expression "ordinarily accessible"
means the overhead line could be reached by hand if
any scaffolding, ladder or other construction was
erected or placed on/in, against or near to a building
or structure.
4.6.3 Precautions Against Access and Warnings of
Dangers
Every support carrying a high voltage overhead line
shall, if the circumstances reasonably require, be fitted
with devices to prevent, so far it is reasonably
practicable, any unauthorised person from reaching a
position at which any such line would be a source of
danger.
Every support carrying a high voltage overhead line,
and every support carrying a low voltage overhead line
incorporating bare phase conductors, shall have
attached to it sufficient safety signs and placed in such
positions as are necessary to give due warning of
such danger as is reasonably foreseeable in the
circumstances.
Poles supporting overhead lines near the road junctions
and turnings shall be protected by a masonry or earth
fill structure or metal barricade, to prevent a vehicle
from directly hitting the pole, so that the vehicle, if out
of control, is restrained from causing total damage to
the live conductor system, likely to lead to a hazardous
condition on the road or foot path or building.
4.6.4 Fitting of Insulators to Stay Wires
Every stay wire which forms part of, or is attached to,
any support carrying an overhead line incorporating
bare phase conductors (except where the support is a
lattice steel structure or other structure entirely of metal
and connected to earth) shall be fitted with an insulator
no part of which shall be less than 3 m above ground
or above the normal height of any such line attached
to that support.
4.7 Maps of Underground Networks
4.7.1 Any person or organization or authority laying
cables shall contact the local authority in charge of that
area and find out the layout of
a) water distribution pipe lines in the area;
b) sewage distribution network;
c) telecommunication network; and
d) gas pipeline network and plan the cable
network in such a manner that the system is
compatible, safe and non interfering either
during its installation or during its operation
and maintenance. Plan of the proposed cable
installation shall be brought to the notice of
the other authorities referred above.
4.7.2 Suitable cable markers and danger sign as would
be appropriate for the safety of the workmen of any of
the systems shall be installed along with the cable
installation. Notification of testing and energisation of
the system shall also be suitably published for ensuring
safety.
4.7.3 Any person or organization or authority laying
cables shall have and, so far it is reasonably practicable,
keep up to date, a map or series of maps indicating the
position and depth below surface level of all networks
or parts thereof which he owns or operates.
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
15
Any map prepared or kept shall be available for
inspection by any of the municipal authority, other
service providers, general public provided they have a
reasonable cause for requiring to inspect any part of
the map.
5 DISTRIBUTION OF SUPPLY AND CABLING
5.0 General
In the planning and design of an electrical wiring
installation, due consideration shall be made of all the
prevailing conditions. It is recommended that advice
of a competent electrical engineer be sought at the
initial stage itself with a view to providing an
installation, that will prove adequate for its intended
purpose be reliable and safe and efficient.
A certain redundancy in the electrical system is
necessary and has to be built in from the initial
design stage itself. The extent of redundancy will
depend on the type of load, its criticality, normal hours
of use, quality of power supply in that area,
coordination with the standby power supply, capacity
to meet the starting current requirements of large
motors etc.
5.1 System of Supply
5.1.1 All electrical apparatus shall be suitable for the
voltage and frequency of supply.
5.1.2 In case of connected load of 100 kVA and above,
the relative advantage of high voltage three-phase
supply should be considered. Though the use of high
voltage supply entails the provisions of space for the
capital cost of providing suitable transformer substation
at the consumer's premises, the following advantages
are gained:
a) advantage in tariff;
b) more effective earth fault protection for heavy
current circuits;
c) elimination of interference with supplies to
other consumers permitting the use of large
size motors, welding plant, etc; and
d) better control of voltage regulation and more
constant supply voltage.
NOTE — Additional safety precautions required to
be observed in HV installations shall also be kept in
view.
In many cases there may be no choice available to the
consumer, as most of the licensees have formulated
their policy of correlating the supply voltage with the
connected load or the contract demand. Generally the
supply is at 400/230 volts, 1 1 kV (or 22 kV) for loads
up to 5 MVA and 33 kV or 66 kV for consumers of
more than 5 MVA.
5.1.3 In very large industrial buildings where heavy
electric demands occur at scattered locations, the
economics of electrical distribution at high voltage
from the main substation to other subsidiary
transformer substations or to certain items of plant,
such as large motors and furnaces, should be
considered. The relative economy attainable by use of
medium or high voltage distribution and high voltage
plant is a matter for expert judgement and individual
assessment in the light of experience by a professionally
qualified electrical engineer.
5.2 Substation Equipment and Accessories
Substations require an approval by the Electrical
Inspectorate. Such approval is mandatory before
energizing the substation. It is desirable to get the
approval for the general layout, schematic layout,
protection plan etc, before the start of the work from
the Inspectorate. All substation equipment and
accessories and materials, etc, shall conform to relevant
Indian Standards wherever they exist, otherwise the
consumer (or his consultant) has to specify the
standards to which the equipment to be supplied
confirms and that shall be approved by the authority.
Manufacturers of equipment have to furnish certificate
of conformity as well as type test certificates for record,
in addition to specified test certificates for acceptance
tests and installation related tests for earthing, earth
continuity, load tests and tests for performance of
protective gear.
5.2.1 High Voltage Switchgear
5.2.1.1 The selection of the type of high voltage
switchgear for any installation inter alia depends upon
the following:
a) voltage of the supply system;
b) the prospective short-circuit current at the
point of supply;
c) the size and layout of electrical installation;
d) the accommodation available; and
e) the nature of industry.
Making and breaking capacity of switchgear shall be
commensurated with short-circuit potentialities of the
supply system and the supply authority shall be
consulted on this subject.
5.2.1.2 Guidelines on various types of switchgear
equipment and their choice for a particular application
shall be in accordance with good practice [8-2(4)],
5.2.1.3 In extensive installations of switchgear (having
more than four incoming supply cables or having more
than 12 circuit breakers), banks of switchgears shall
be segregated from each other by means of fire-
resisting barriers having 2 h fire resistance rating in
16
NATIONAL BUILDING CODE OF INDIA
order to prevent spreading of the risk of damage by
fire or explosion arising from switch failure. Where a
bus-bar section switch is installed, it shall also be
segregated from adjoining banks in the same way [see
8-2(5)]. Except main LT panel, it would be preferable
to locate the sub panels/distribution boards near load
centre. Further, it should be ensured that these panels
are easily approachable. The preferable location of
panels shall be near the exitways.
5.2.1.4 It should be possible to isolate any section from
the rest of the switchboards such that work might be
undertaken on this section without the necessity of
making the switchboard dead. Isolating switches used
for the interconnection of sections or for the purpose
of isolating circuit-breakers of other apparatus, shall
also be segregated within its compartment so that no
live part is accessible when work in a neighbouring
section is in progress.
5.2.1.5 In the case of duplicate or ring main supply,
switchgears with interlocking arrangement shall be
provided to prevent simultaneous switching of two
different supply sources. Electrical and/or mechanical
interlocks may preferably be provided.
5.2.2 Cables
5.2.2 .1 The smallest size of the cable that shall be used,
will depend upon the method of laying cable,
permissible maximum temperature it shall withstand,
voltage drop over the length of the cable, the
prospective short-circuit current to which the cable may
be subjected, the characteristics of the overload
protection gear installed, load cycle and thermal
resistivity of the soil [see also 8-2(6)].
NOTE — Guidelines for correlation of the ratings of cables
and characteristics of protective device are under consideration.
Continuous current carrying capacity (thermal limit leading
to permanent change in properties of the insulation) under the
installed conditions, voltage drop under required load and the
fault current withstand ability of the cable for the duration
that the protective device controlling the cable installation will
let go the fault current, operating voltage are the prime
considerations.
5.2.2.2 The advice of the cable manufacturer with
regard to installation, jointing and sealing shall be
followed.
5.2.2.3 The HV cables shall either be laid on the cable
rack/built-up concrete trenches/tunnel/basement or
directly buried in the ground depending upon the
specific requirement. It is preferable to use four core
cable in place of three and half core to minimize heating
of neutral core due to harmonic content in the supply
system and also avoidance of overload failures. All
cables shall be installed in accordance with good
practice [8-2(6)].
5.2.2.4 Colour identification of cores of non-flexible
cables
Function
Colour Identification
of Core of Rubber of
PVC Insulated Non-
flexible Cable, or of
Sleeve or Disc to be
Applied to Conductor
or Cable Code
Protective or earthing '
Green and yellow or
Green with yellow
stripes 1}
Neutral of ax. single or three-
Black
phase circuit
Phase R of 3-phase a.c. circuit
Red
Phase Y of 3-phase a.c. circuit
Yellow
Phase B of 3-phase a.c. circuit
Blue
Positive of d.c. 2-wire circuit
Red
Negative of d.c. 2-wire circuit
Black
Outer (positive or negative) of
Red
d.c. 2-wire circuit derived from
3 -wire system
Positive of 3-wire system
Red
positive of 3-wire d.c. circuit)
Middle wire of 3-wire d.c.
Black
circuit
Negative of 3-wire d.c. circuit
Blue
Functional Earth-
Cream
Telecommunication
l) Bare conductors are also used for earthing and earth continuity
conductors. But it is preferable to use insulated conductors with
green insulation with yellow stripes.
5.2.2.5 Colour, identification of cores of flexible cables
and flexible cords
Number of Function of Core Colour(s) of Core
Cores
1 Phase Brown 1}
Neutral (Light) Blue
Protective or Earthing Green & yellow
Phase
Neutral
Brown
(Light) Blue r)
3 Phase Brown
Neutral (light) Blue 1}
Protective or Earthing Green & yellow
4 or 5 Phase Brown or Black !)
Neutral (Light) Blue 15
Protective or Earthing Green & yellow
Certain alternatives are allowed in Wiring Regulations.
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
17
5.2.3 High Voltage Busbar Trunking/Ducting
High voltage busbar trunking system is a type-tested
switchgear and control gear assembly in the form of
an enclosed system. HV bus bar system is used
for transporting power between HV Generators,
transformers and the infeed main switchgear of the
main HV switchgear.
Generally three types of bus ducts namely non-
segregated, segregated and isolated phase bus duct shall
be used. The non-segregated bus ducts consists of three
phase busbars running in a common enclosure made
of steel or aluminium. The enclosure shall provide
safety for the operational personnel and reduces
chances of faults. The enclosures shall be effectively
grounded.
Segregated phase bus duct are similar to non-
segregated phased duct except that metal or insolation
barriers are provided between phase conductors to
reduce chances of phase to phase faults. However, it is
preferable to use metal barriers.
In the case of isolated bus ducts, each phase conductor
shall be housed in a separate non-magnetic enclosures.
The bus duct shall be made of sections which are
assembled together at site to make complete assembly.
The enclosure shall be of either round or square shape
and welded construction. The enclosures of all phases
in general to be supported on a common steel structure.
Provision of fire protection shall be provided in all
openings in accordance with Part 4 'Fire and Life
Safety'. Fire separation in openings shall be provided
using materials having 2h fire resistance rating.
5.2.4 MV/LV Busbar Trunking/Rising Mains
Where heavy loads are to be carried, busbar systems
are preferred. The busbars are available for continuous
run from point to point or with tap offs at standard
intervals and have to be chosen as per specific
requirement. MV/LV busbar trunking shall be a type-
tested switchgear and control gear assembly in the form
of an enclosed system. There are two types of MV/LV
bus duct system for power distribution system:
a) Conventional type.
b) Compact and sandwich type.
Conventional type bus duct is used for large power
handling between transformer and switchgear or
between switchgear and large power loads, such as
compressor drive motor etc. This type is generally used
in plant rooms, riser shafts, substations etc.
Compact type is available either air insulated or
sandwich type for use within areas of the building
which are put to other higher (aesthetic) level of use.
They could be used in false ceiling spaces or even in
corridors and shafts for distribution without any false
ceiling as they provide an aesthetically acceptable
finish to merge with other building elements such as
beams, ducts or pipes in functional buildings.
The class of protection shall be specific depending on
the requirement at the place of installation. Protection
class (IP xx) will automatically identify the ventilation,
protection from weather, water, dust etc.
In modern building technology, high demands are
made of the power distribution system and its
individual components;
a) Long life and good service quality,
b) Safe protection in the event of fire,
c) Low fire load,
d) Low space requirement, and
e) Minimum effort involved in carrying out
retrofits.
The high load density in modern large buildings and
high rise buildings demands compact and safe solution
for the supply of power. The use of busbar trunking
system is ideal for such applications.
Bus bar trunking can be installed in vertical risers ducts
or horizontally in passages for transmission and
distribution of power. Busbar trunking systems allow
electrical installations to be planned in a simple and
clear fashion. In the building complexes, additional
safety demands with respect to fire barriers and fire
load and use of bus bar trunking meets this requirement.
Busbar trunking system reduces the combustible
material near the area with high energy in comparison
with other distribution systems such as cables and
makes the building safe from the aspect of vulnerability
to fire of electrical origin. In addition, unlike cable
systems the reliability of a bus trunking system is vvery
high. These systems also require very little periodic
maintenance.
Choice of busbar trunking for distribution in buildings
can be made on the basis of
a) reduced fire load (drastically reduced in
comparison to the cable system),
b) reduced maintenance over its entire lifetime,
c) longer service lifetime in comparison with a
cable distribution
d) enhanced reliability due to rigid bolted
joints and terminations and extremely low
possibility of insulation failure.
5.2.5 Transformers
5.2.5.1 General design objective while selecting the
transformer(s) for a substation would be to provide at
least two or more transformers, so that a certain amount
18
NATIONAL BUILDING CODE OF INDIA
of redundancy is built in, even if a standby system is
provided. The total installed transformation capacity
would be marginally higher than the anticipated
maximum demand. With growing emphasis on energy
conservation, the system design is made for both
extremes of loading. During the periods of lowest load
in the system, it would be desirable to operate only
one transformer and switch in additional transformers
as the load variation takes place in a day. The minimum
size of a transformer would quite often depend on the
minimum load that is anticipated over a period of about
4 h in a day. Total transformer capacity is generally
selected on the basis of present load, possible future
load, operation and maintenance cost and other system
conditions and selection of the maximum size
(capacity) of the transformer is guided by short-circuit
making and breaking capacity of the switchgear used
in the medium voltage distribution system. Maximum
size limitation is important from the aspect of feed to
a down stream fault.
For feeding final single phase domestic type of loads
or general office loads it is advisable to even use
transformers of capacity much lower than what the
switchgear can handle, so that lower fault MVA is
available in such areas and use of hand held equipment
fed through flexible cords is safe.
For reasons of reliability and redundancy it is normal
practice to provide at least two transformers for any
important installation. Interlinking by tie lines is an
alternative to enhance reliability /redundancy is areas
where there are a number of substations in close
vicinity, such as a campus with three or four multi-
storeyed blocks each with a substation.
Ring main type of distribution is preferred for
complexes having a number of substations.
5.2.5.2 Where two or more transformers are to be
installed in a substation to supply a medium voltage
distribution system, the distribution system shall be
divided into separate sections each of which shall be
normally fed from one transformer only unless the
medium voltage switchgear has the requisite short-
circuit capacity. Provision may, however, be made to
interconnect separate sections, through a bus coupler
in the event of failure or disconnection of one
transformer. See 4.2 for details of location and
requirements of substation.
The transformers, that may at any time operate in
parallel, shall be so selected as to share the load in
proportion to their respective load ratings. While the
general practice is to avoid operation of transformers
in parallel for feeding final distribution in buildings, it
is possible to use transformers with slightly different
impedance or voltage taps to operate in parallel, but
with appropriate protection. Installations designed for
parallel operation of transformers shall have protection
for avoiding circulating current between transformers,
avoid overload of any one transformer due to reactance
mismatch and the system shall be so arranged as to
trip the secondary breaker in case the primary breaker
of that transformer trips.
5.2.6 Switchgear
5.2.6.1 Switchgear (and its protective device) shall
have breaking* capacity not less than the anticipated
fault level in the system at that point. System fault level
at a point in distribution system is predominantly
dependent on the transformer size and its reactance.
Parallel operation of transformers naturally increases
the fault level
5.2.6.2 Isolation and controlling circuit breaker shall
be interlocked so that the isolator cannot be operated
unless the corresponding breaker is in open condition.
The choice between alternative types of equipment may
be influenced by the following considerations:
a) In certain installations supplied with electric
power from remote transformer substations, it
may be necessary to protect main circuits with
circuit-breakers operated by earth fault, in
order to ensure effective earth fault protection.
b) Where large electric motors, furnaces or other
heavy electrical equipment is installed, the
main circuits shall be protected from short-
circuits by switch disconnector fuse or
circuit breakers. For motor protection, the
combination of contactor overload device and
fuse or circuit breakers shall be Type-2 co-
ordinated in accordance with accepted
standards [8-2(7)]. Wherever necessary, back
up protection and earth fault protection shall
be provided to the main circuit.
c) Where mean of isolating main circuits is
separately required, switch disconnector fuse
or switch disconnector may form part of main
switchboards.
5.2.6.3 It shall be mandatory to provide power factor
improvement capacitor at the substation bus. Suitable
capacitor may be selected in consultation with the
capacitor as well as switchgear manufacture depending
upon the nature of electrical load anticipated on the
system. Necessary switchgear/feeder circuit breaker
shall be provided for controDing of capacitor bank.
Power factor of individual motor may be improved by
connecting individual capacitor banks in parallel. For
higher range of motors, which are running continuously
without much variation in load, individual power factor
correction at load end is advisable.
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
19
NOTE — Care should be taken in deciding the kVA rating of
the capacitor in relation to the magnetising kVA of the motor.
Over rating of the capacitor may cause injury to the motor and
capacitor bank. The motor still rotating after disconnection
from the supply, may act as generator by self-excitation and
produce a voltage higher than supply voltage. If the motor is
again switched on before the speed has fallen to about
80 percent of the normal running speed, the high voltage will
be superimposed on the supply circuits and will damage both
the motor and capacitor.
As a general rule, the kVAr rating of the capacitor
should not exceed the no-load magnetising kVA of
the motor.
Generally it would be necessary to provide an
automatic control for switching in capacitors matching
the load power factor and the bus voltage. Such a
scheme would be necessary as capacitors permanently
switched in the circuit may cause over voltage at times
of light load.
5.2.6.4 Sufficient additional space shall be allowed in
substations and switchrooms to allow operation and
maintenance and proper means shall be provided for
isolating the equipment to allow access for servicing,
testing and maintenance. Sufficient additional space
shall be allowed for temporary location and installation
of standard servicing and testing equipment. Space
should also be allowed to provide for anticipated future
extensions.
5.2.6.5 Electrical installations in a room or cubicle or
in an area surrounded by wall fence, access to which
is controlled by lock and key shall be considered
accessible to authorized persons only.
A wall or fence less than 1.8 m in height shall not be
considered as preventing access unless it has other
features that provide a degree of isolation equivalent
to a 1.8 m fence.
5.2.6.6 Harmonics on the supply systems are
becoming a greater problem due to the increasing use
of electronic equipments, computer, fluorescent,
mercury vapour and sodium vapour lighting, controlled
rectifier and inverters for variable speed drives, power
electronics and other non-linear loads. Harmonics may
lead to almost as much current in the neutral as in the
phases. This current is almost entirely third harmonic.
Phase rectification devices may be considered for the
limits of harmonic voltage distortion may be
considered at the planning stage in such cases.
With the wide spread use of thyristor and rectifier based
loads there is necessity of providing a full size neutral;
but this requirement is limited to the 3-phase 4-wire
distribution generally in the 400/230 V system. As a
result it is not desirable to use half-size neutral
conductor, as possibility of neutral conductor overload
due to harmonics is likely.
5.3 Reception and Distribution of Main Supply
5.3.1 Control at Point of Commencement of Supply
5.3.1.1 There shall be a circuit-breaker or miniature
circuit-breakers or a load break switch fuse on each
live conductor of the supply mains at the point of entry.
The wiring throughout the installation shall be such
that there is no switch or fuse unit in the earthed neutral
of conductor. The neutral shall also be distinctly
marked. In this connection, Rule 32(2) and Rule 50(1)
of the Indian Electricity Rules, 1956 (see Annex B) as
amended up to date shall also be referred.
5.3.1.2 The main switch shall be easily accessible and
situated as near as practicable to the termination of
service line.
5.3.1.3 On the main switch, where the conductors
include an earthed conductor of a two-wire system or
an earthed neutral conductor or a multi-wire system or
a conductor which is to be connected thereto, an
indication of a permanent nature shall be provided to
identify the earthed neutral conductor. In this
connection, Rule 32(1) of Indian Electricity Rules y
1956 (see Annex B) shall be referred as amended up-
to-date.
5.3.1.4 Energy meters
Energy meters shall be installed in residential buildings
at such a place which is readily accessible to the owner
of the building and the Authority. These should be
installed at a height where it is convenient to note the
meter reading, it should preferably not be installed
below one metre from the ground. The energy meters
should either be provided with a protecting covering,
enclosing it completely except the glass window
through which the readings are noted or should be
mounted inside a completely enclosed panel provided
with hinged or sliding doors with arrangement for
locking.
In multi-storeyed buildings meters shall be installed
with tapping point for meters of the rising main (bus
trunking) on individual floors.
5.3.2 Main Switches and Switchboard
5.3.2.1 All main switches shall be either of metal-clad
enclosed pattern or of any insulated enclosed pattern
which shall be fixed at close proximity to the point
of entry of supply. Every switch shall have an
environmental protection level rating (IP), so that its
operation is satisfactory in the environment of the
installation.
NOTE — Woodwork shall not be used for the construction or
mounting of switches and switch boards installed in a building,
5.3.2.2 Location
a) The location of the main board should be such
20
NATIONAL BUILDING CODE OF INDIA
that it is easily accessible for fireman and
other personnel to quickly disconnect the
supply in case of emergencies. If the room is
locked for security, means of emergency
access, by schemes such as break glass
cupboard, shall be incorporated.
b) Main switch board shall be installed in rooms
or cupboards so as to safeguard against
operation by unauthorized personnel.
c) Switchboards shall be placed only in dry
situations and in ventilated rooms and they
shall not be placed in the vicinity of storage
batteries or exposed to chemical fumes.
d) In damp situation or where inflammable or
explosive dust, vapour or gas is likely to be
present, the switchboard shall be totally
enclosed and shall have adequate degree
of protection. In some cases flameproof
enclosure may be necessitated by particular
circumstances [see 8-2(8)].
e) Switchboards shall not be erected above gas
stoves or sinks, or within 2.5 m or any
washing unit in the washing rooms or
laundries, or in bathrooms, lavatories or
toilets, or kitchens.
f) In case of switchboards unavoidably fixed in
places likely to be exposed to weather, to drip,
or to abnormal moist temperature, the outer
casing shall be weatherproof and shall be
provided with glands or bushings or adopted
to receive screwed conduit, according to the
manner in which the cables are run.
g) Adequate illumination shall be provided for
all working spaces about the switchboards
when installed indoors.
5.3.2.3 Metal-clad switchgear shall preferably be
mounted on any of the following types of boards:
a) Hinged-type metal boards — These shall
consist of a box made of sheet metal not less
than 2 mm thick and shall be provided with a
hinged cover to enable the board to swing
open for examination of the wiring at the back.
The joints shall be welded. There shall be a
clear distance of not less than 2.5 cm between
the teak wood board and the cover, the
distance being increased for larger boards in
order that on closing of the cover, the
insulation of the cables is not subjected to
damage and no excessive twisting or bending
in any case. The board shall be securely fixed
to the wall by means of rag bolts, plugs, or
wooden plugs and shall be provided with a
locking arrangement and an earthing stud. All
wires passing through the metal board shall
be protected by a rubber or wooden bush
at the entry hole. The earth stud should
commensurate with the size of earth lead/
leads. Alternatively, metal boards may be
made of suitable size angle iron of minimum
size 35 mm x 35 mm x 6 mm or channel iron
of minimum size 35 mm x 25 mm x 6 mm
frames work suitably mounted on front with
a 3 mm thick mild steel plate and on back with
1.5 mm thick mild steel sheet. No apparatus
shall project beyond any edge of panel. No
fuse body shall be mounted within 2.5 cm of
any edge of the panel.
NOTE — Such type of boards are particularly suitable
for small switchboard for mounting metal-clad
switchgear connected to supply at low voltages.
b) Fixed-type metal boards — These shall
consist of an angle or channel iron frame fixed
on the wall or on floor and supported on the
wall at the top, if necessary. There shall be
a clear distance of 1 m in front of the
switchboards. If there are any attachments
of bare connections at the back of the
switchboard Rule 51(1 )(c) of Indian Electricity
Rules, 1956 shall apply. The connections
between the switchgear mounting and the
outgoing cable up to the wall shall be enclosed
in a protection pipe.
NOTE — Such type of boards are particularly suitable
for large switchboards for mounting large number of
switchgears or high capacity metal-clad switchgear or
both.
c) Protected-type switchboard — A protected
switchboard is one where all of the conductors
are protected by metal or other enclosures.
They may consist of a metal cubicle panel, or
an iron frame upon which is mounted metal-
clad switchgear. They usually consist of a
main switch, busbars and circuit breakers or
fuses controlling outgoing circuits.
d) Open-type switchboard — An open type
switchboard is one, which has exposed current
carrying parts on the front of the switchboard.
This type of switchboard is rarely used now-
a-days but where, this exists, a hand rail
or barrier has to be provided to prevent
unintentional or accidental contact with
exposed live parts. They must be located in a
special switch room or enclosure and only a
competent person may have access to these
switchboards.
NOTE — These boards may be existing in old
installations. It is recommended that they be phased
out. With the continuously increasing fault power feed
due to increases in generation and strengthening of
distribution systems, these open boards are a source of
accidents.
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
21
5.3.2.4 Recessing of boards
Where so specified, the switchboards shall be recessed
in the wall. Ample room shall be provided at the back
for connection and at the front between the switchgear
mountings.
5.3.2.5 Marking of apparatus [see also 8-2(9)]
a) Where a board is connected to voltage higher
than 250 V, all the apparatus mounted on it
shall be marked on the following colours to
indicate the different poles or phases to which
the apparatus or its different terminals may
have been connected:
Alternating Current Direct Current
Three-phases — red, Three-wire system
yellow, blue — 2 outer wire,
positive red and
negative blue
1 Neutral — black 1 Neutral — black
Where four-wire three-phase wiring is done,
the neutral shall be in one colour and the other
three wires in another colour as mentioned
above or shall be suitably tagged or sleeved
for fool proof identification.
b) Where a board has more than one switch, each
such switch shall be marked to indicate which
section of the installation it controls. The main
switch shall be marked as such and where
there is more than one main switch in the
building, each such switch shall be marked
to indicate which section of the installation it
controls.
All markings shall be clear and permanent.
5.3.2.6 Drawings
Before proceeding with the actual construction, a
proper drawing showing the detailed dimensions and
design including the disposition of the mountings of
the boards, which shall be symmetrically and neatly
arranged for arriving at the overall dimensions, shall
be prepared along the building drawing. Such drawings
will show the mandatory clearance spaces if any, and
clear height below the soffit of the beam required to
satisfy regulations and safety considerations, so that
other designers or installers do not get into such areas
or spaces for their equipment.
5.3.2.7 Where a board has more than one switch, each
such switch shall be marked to indicate which section
of the installation it controls. The main switch shall be
marked as such and where there is more than one main
switch in the building, each such switch shall be marked
to indicate which section of the installation it controls.
All markings shall be clear and permanent.
5.3.2.8 MV/LV Busbar chambers (400 V/230 V)
Busbar chambers, which feed two or more circuits,
must be controlled by a main disconnector (TP & N),
or Isolating links or TPN MCB to enable them to be
disconnected from the supply,
5.3.3 Distribution Boards
A distribution board comprises of one or more protective
devices against over current and ensuring the distribution
of electrical energy to the circuits. Distribution board
shall provide plenty of wiring space, to allow working
as well as to allow keeping the extra length of connecting
cables, likely to be required for maintenance.
5.5.3.1 Main distribution board shall be provided with
a circuit breaker on each pole of each circuit, or a switch
with a fuse on the phase or live conductor and a link
on the neutral or earthed conductor of each circuit. The
switches shall always be linked.
All incomers should be provided with surge protection
devices.
5.3.4 Branch Distribution Boards
5.3.4.1 Branch distribution boards shall be provided,
along with earth leakage protective device (ELCB)
(incoming), with a fuse or a miniature circuit breaker
or both of adequate rating/setting chosen on the live
conductor of each sub-circuit and the earthed neutral
conductor shall be connected to a common link and be
capable of being disconnected individually for testing
purposes. At least one spare circuit of the same capacity
shall be provided on each branch distribution board.
Further, the individual branching circuits (outgoing)
shall be protected against over-current with miniature
circuit breaker of adequate rating. In residential/
industrial lighting installations, the various circuits
shall be separated and each circuit shall be individually
protected so that in the event of fault, only the particular
circuit gets disconnected.
5.3.4.2 Circuits shall be separate for installations at
higher level such as those in the ceiling and at higher
levels, above 1 m, on the walls and for installations at
lower level such as sockets for portable or stationery
plug in equipments. For devices consuming high power
and which are to be supplied through supply cord and
plug, separate wiring shall be done. For plug-in
equipment provisions shall be made for providing
ELCB protection in the distribution board.
5.3.4.3 It is preferable to have additional circuit for
kitchen and bathrooms. Such sub-circuit shall not have
more than a total of ten points of light, fans and 6A
socket outlets. The load of such circuit shall be
restricted to 800 W. If a separate fan circuit is provided,
the number of fans in the circuit shall not exceed ten.
Power sub-circuit shall be designed according to the
22
NATIONAL BUILDING CODE OF INDIA
load but in no case shall there be more than two 16A
outlets on each sub-circuit.
5.3.4.4 The circuits for lighting of common area shall
be separate. For large halls 3-wire control with individual
control and master control installed near the entrance
shall be provided for effective conservation of energy.
5.3.4.5 Where daylight would be available, particularly
in large halls, lighting in the area near the windows,
likely to receive daylight shall have separate controls
for lights, so that they can be switched off selectively
when daylight is adequate, while keeping the lights in
the areas remote from the windows on.
5.3.4.6 Circuits for socket outlets may be kept separate
circuits feeding fans and lights. Normally, fans and
lights may be wired on a common circuit. In large
spaces circuits for fans and lights may also be
segregated. Lights may have group control in large
halls and industrial areas. While providing group
control consideration may be given for the nature of
use of the area lit by a group. Consideration has to be
given for the daylight utilization, while grouping, so
that a group feeding areas receiving daylight can be
selectively switched off during daylight period.
5.3.4.7 The load on any low voltage sub-circuit shall
not exceed 3 000 W. In case of a new installation, all
circuits and sub-circuits shall be designed with an initial
load of about 2 500 W, so as to allow a provision of 20
percent increase in load due to any future modification.
Power sub-circuits shall be designed according to the
load, where the circuit is meant for a specific
equipment. Good practice is to limit a circuit to a
maximum of four sockets, where it is expected that
there will be diversity due to use of very few sockets
in large spaces (example sockets for use of vacuum
cleaner). General practice is to limit it to two sockets
in a circuit, in both residential and non-residential
buildings and to provide a single socket on a circuit
for a known heavy load appliance such as air
conditioner, cooking range etc.
5.3.4.8 In wiring installations at special places like
construction sites, stadium, shipyards, open yards in
industrial plants, etc, where a large number of high
wattage lamp may be required, there shall be no
restriction of load on any circuit but conductors used
in such circuits shall be of adequate size for the load
and proper circuit protection shall be provided.
5.3.5 Location of Distribution Boards
a) The distribution boards shall be located as
near as possible to the centre of the load they
are intended to control.
b) These shall be fixed on suitable stranehion or
wall and shall be accessible for replacement/
reset of protective devices, and shall not be
more than 1.8 m from floor level.
c) These shall be of either metal-clad type, or
air insulated type. But, if exposed to weather
or damp situations, these shall be of the
weatherproof type and, if installed where
exposed to explosive dust, vapour or gas,
these shall be of flameproof type in
accordance with accepted standards [8-2(10)1.
In corrosive atmospheres, these shall be
treated with anti-corrosive preservative or
covered with suitable plastic compound.
d) Where two and/or more distribution boards
feeding low voltage circuits are fed from a
supply of medium voltage, the metal case shall
be marked 'Danger 415 V and identified with
proper phase marking and danger marks.
e) Each shall be provided with a circuit list
giving diagram of each circuit which it
controls and the current rating of the circuit
and size of fuse element.
f) In wiring branch distribution board, total load
of consuming devices shall be divided as far
as possible evenly between the number of
ways in the board leaving spare circuits for
future extension.
5.3.6 Protection of Circuits
a) Appropriate protection shall be provided at
switchboards, distribution boards and at all
levels of panels for all circuits and sub-circuits
against short circuit, over-current and other
parameters as required. The protective device
shall be capable of interrupting maximum
prospective short circuit current that may
occur, without danger. The ratings and
settings of fuses and the protective devices
shall be co-ordinated so as to afford selectivity
in operation and in accordance with accepted
standards [8-2(1)].
b) Where circuit-breakers are used for protection
of a main circuit and of the sub-circuits
derived therefrom, discrimination in operation
may be achieved by adjusting the protective
devices of the sub-main circuit-breakers to
operate at lower current settings and shorter
time-lag than the main circuit-breaker.
c) Where HRC type fuses are used for back-up
protection of circuit-breakers, or where HRC
fuses are used for protection of main circuits,
and circuit-breakers for the protection of sub-
circuits derived there from, in the event of
short-circuits protection exceeding the short-
circuits capacity of the circuit-breakers, the
HRC fuses shall operate earlier than the
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
23
circuit-breakers; but for smaller overloads
within the short-circuit capacity of the circuit-
breakers, the circuit-breakers shall operate
earlier than the HRC fuse blows.
d) If rewireable type fuses are used to protect
sub-circuits derived from a main circuit
protected by HRC type fuses, the main circuit
fuse shall normally blow in the event of a
short-circuit or earth fault occurring on sub-
circuit, although discrimination may be
achieved in respect of overload currents. The
use of rewireable fuses is restricted to the
circuits with short-circuit level of 4 kA; for
higher level either cartridge or HRC fuses
shall be used. However, use of rewireable fuse
is not desirable, even for lower fault level
areas. MCB ' s provide a better and dependable
protection, as their current setting is not
temper able.
e) A fuse carrier shall not be fitted with a fuse
element larger than that for which the carrier
is designed.
f) The current rating of a fuse shall not exceed
the current rating of the smallest cable in the
circuit protected by the fuse.
g) Every fuse shall have its own case or cover
for the protection of the circuit and an
indelible indication of its appropriate current
rating in an adjacent conspicuous position.
5.4 Voltage and Frequency of Supply
It should be ensured that all equipment connected to
the system including any appliances to be used on it
are suitable for the voltage and frequency of supply of
the system. The nominal values of low and medium
voltage systems in India are 240 V and 415 V ac,
respectively, and the frequency 50 Hz.
NOTES
1 The design of the wiring system and the sizes of the cables
should be decided taking into account two factors:
a) Voltage Drop — This should be kept as low as economy
permits to ensure proper functioning of all electrical
appliances and equipment including motors; and
b) First cost against operating losses.
2 In view of the latest development at the international level,
nominal system voltages have been aligned with IEC
recommendation and accordingly the nominal ac system
voltage shall be changed from 240/415 V to 230/400 V with a
tolerance of ± 10 percent.
5.5 Rating of Cables and Equipments
5.5.1 The current-carrying capacity of different types
of cables shall be chosen in accordance with good
practice [8-2(12)].
5.5.2 The current ratings of switches for domestic and
similar purposes are 6A and 16A.
5.5.3 The current ratings of isolators and normal duty
switches and composite units of switches and fuses
shall be selected from one of the following values:
16, 25, 32, 63, 100, 160, 200, 320, 400, 500, 630,
800, 1 000 and 1 250 A.
5.5.4 The ratings of rewirable and HRC fuses shall be
in accordance with good practice [8-2(13)].
5.5.5 The current ratings of miniature circuit-breakers
shall be chosen from the values given below:
6, 8, 10, 13, 16, 20, 25, 32, 40, 50, 63, 80, 100 and
125 A.
5.5.6 The current ratings of moulded case circuit-
breakers shall be chosen from the values given
below:
100, 125, 160,200,250,315,400,630,800, 1 000,
1 250 and 1 600 A.
5.5.7 The current ratings of air circuit-breakers shall,
be chosen from the values given below:
630, 800, 1 000, 1 250, 1 600, 2 000, 2 500, 3 200
and 4 000 A.
5.5.8 The current ratings of the distribution fuse board
shall be selected from one of the following values:
6, 16, 25, 32, 63 and 100 A.
5.6 Installation Circuits
Type of Circuit
Wire Size
Number of Circuits
Lighting
1.0 mm 2
2 or more
Socket-outlets 10 A
2.5 mm 2
Any number
Areas such as
kitchens and
laundries 3 x
double socket-
outlets per circuit.
Other areas up to
12 double socket-
outlets
Socket-outlets 15 or
2.5 mm 2
1
20 A
Water heater 3 kW
1.5 mm 2
1
Water heater 3-6 kW
2.5 mm 2
1
Free standing electric
6.0 mm 2
1
range
Separate oven and/
4.0 mm 2
1
or cook top
Permanently connec-
2.5 mm 2
1 above 10 A. Up
ted appliances
to 10 A can te
including dish-
wired as part of a
washers, heaters, etc
socket-outlet circuit
Submains to garage
2.5 mm 2
1 for each
or out-building
Mains cable
16 mm 2
1
24
NATIONAL BUILDING CODE OF INDIA
5.6.1 Selecting and Installing Cables
5.6.1.1 Cable insulation types
For the mains cable
For installation wiring
For main earth or main equipotential wire
Underground installation and installation in cable
trench, feeders between buildings etc.,
Installation in plant rooms, switch rooms etc, on
cable tray or ladder or protected trench, where risk
of mechanical damage to cable does not exist.
Tough plastic sheathed (TPS) cable
Tough plastic sheathed (TPS) cables
Polyvinyl chloride (PVC) insulated conduit wire
PVC insulated, PVC sheathed armoured cables or
XLPE insulated, PVC sheathed cables armoured cables
PVC insulated, PVC sheathed or XLPE insulated,
PVC sheathed unarmoured cables
For the purposes of this Code cables above 1 mm 2 must
have stranded conductors. All cables when installed,
must be adequately protected against mechanical
damage. This can be carried out by either having
additional protection, such as being enclosed in PVC
conduit or metal pipes, or placing the cables in a
5.6.1.2 Circuit wire sizes
suitable location that requires no additional protection.
The cables for wiring circuits in electrical installation
must have the appropriate wire size matching the
requirement of the loads and the following table gives
the recommendations for different types of loads.
Circuits
1-way lighting
2-way lighting control (straps
between the 2 switches)
Storage water heaters up to 3 kW
Storage water heaters between
3kWand6kW
Socket-outlets and permanent
connection units
Submains to garages or out
buildings
Cooking hobs
Separate ovens
Electric range
Mains
Main equipotential bonding wire
Main earth wire
2 + E is also known as twin and earth
Minimum Wire Size
2 + E cable wires 1.5 mm 2
3-wire cable 1.5 mm 2
2 + E cable 1 .5 mm (stranded
conductors)
2 + E cable 2.5 mm 2 (stranded
conductors)
2 + E cable 2.5 mm 2 (stranded
conductors)
2 + E cable 2.5 mm 2 (stranded
conductors)
2 + E cable 4 mm 2
2 + E cable 4 mm 2 (stranded
conductors)
2 + E cable 6 mm 2 (stranded
conductors)
2 wire cable 16 mm 2 (stranded
conductors)
Conduit wire 4 mm 2 (stranded
conductors)
Conduit wire 6 mm 2 (stranded
conductors)
Wire Colour
Red-Black-Green or Green/Yellow
Red-White-Blue
Red-Black-Green or Green/Yellow
Red-Black-Green or Green/Yellow
Red-Black-Green or Green/Yellow
Red-Black-Green or Green/Yellow
Red-Black-Green or Green/Yellow
Red-Black-Green or Green/Yellow
Red-Black
Green or Green/Yellow
Green or Green/Yellow
Switch or isolator controlling a water heater or geyser
should not be located within 1 m from the location of
a shower or bath tub, to avoid a person in wet condition
reaching the switch or isolator. It is preferable to
provide the control switch outside the bathroom near
the entrance and provide an indication at the water
heater. A socket or a connector block with suitable
protection against water spray should be provided to
connect the water heater. The above considerations
apply to switches for outdoor lights and other
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
25
appliances, with the object of avidance of operation of
a switch when a person is wet. Sockets in kitchen,
bathroom, toilet, garage etc, should not be provided
within a height of 1 m from the ground level. Similar
care has to be taken for installations involving
fountains, swimming pools etc. Light fittings in such
areas should be fed at low voltage, preferably through
an isolating transformer with a proper earth leakage
protection.
5.6.2 Requirements for Physical Protection of
Underground Cables
Protective Element
Bricks
Concrete slabs
Plastic slabs
(polymeric cover
strips) Fibre
reinforced plastic
PVC conduit or
PVC pipe or
stoneware pipe or
hume pipe
Galvanized pipe
Specifications
a) 100 mm minimum width
b) 25 mm thick
c) sand cushioning 100 mm
and sand cover 100 mm.
at least 50 mm thick.
at least 10 mm thick,
depending on properties and
has to be matched with the
protective cushioning and
cover
The pipe diameter should be
such so that the cable is able
to easily slip down the pipe.
The pipe diameter should be
such so that the cable is able
to easily slip down the pipe.
The trench shall be backfilled to cover the cable initially
by 200 mm of fill; and then a plastic marker strip over
the full length of cable in the trench. Fill the trench
shall be laid before filling the full trench. The marker
signs where any cable enters or leaves a building shall
be put. This will identify that there is a cable located
underground near the building. If the cables rise above
ground to enter a building or other structure, a
mechanical protection such as a GI pipe or PVC pipe
for the cable from the trench depth to a height of 2.0 m
above ground shall be provided.
5.7 Lighting and Levels of Illumination
5.7.1 General
Lighting installation shall take into consideration the
many factors on which the quality and quantity of
artificial lighting depends. The modern concept is to
provide illumination with the help of a large number
of light sources not of higher illumination level. Also
much higher levels of illumination are called for, than
in the past, often necessitating the use of fluorescent
lighting suitably supplemented with incandescent
fittings, where required.
5.7.2 Future Demand
However, if for financial reasons, it is not possible to
provide a lighting installation to give the recommended
illumination levels, the wiring installation at least
should be so designed that at a later date, it will permit
the provision for additional lighting fittings or
conversion from incandescent to fluorescent lighting
fittings to bring the installation to the required standard.
It is essential that adequate provisions should be made
for all the electrical services which may be required
immediately and during the intended useful life of the
building.
5.7.3 Principles of Lighting
When considering the function of artificial lighting,
attention shall be given to the following principle
characteristics before designing an installation:
a) illumination and its uniformity;
b) special distribution of light. This includes a
reference to the composition of diffused and
directional light, direction of incidence, the
distribution of luminances and the degree of
glare; and
c) colour of the light and colour rendition.
5.7.4 The variety of purposes which have to be kept
in mind while planning the lighting installation could
be broadly grouped as:
a) industrial buildings and processes;
b) offices, schools and public buildings;
c) surgeries and hospitals; and
d) hostels, restaurants, shops and residential
buildings.
5.7.4.1 It is important that appropriate levels of
illumination for these and the types and positions of
fittings determined to suit the task and the disposition
of the working planes.
5.7.5 For specific requirements for lighting of special
occupancies, reference shall be made to good practice
18-2(14)].
5.7.6 Energy Conservation
Energy conservation may be achieved by using the
following:
a) Energy efficient lamps, chokes, ballast, etc
for lighting equipment.
b) Efficient switching systems such as remote
sensors, infrared switches, master switches,
remote switches, etc for switching ON and
OFF of lighting circuits.
c) Properly made/connected joints/contacts to
avoid loose joints leading to loss of power.
26
NATIONAL BUILDING CODE OF INDIA
5.8 In locations where the system voltage exceeds
650 V, as in the case of industrial locations, for
details of design and construction of wiring
installation, reference may be made to good practice
[8-2(15)].
5.9 Guideline for Electrical Layout in Residential
Buildings
For guidelines for electrical installation in residential
buildings, reference may be made to good practice
[8-2(16)].
A typical distribution scheme in a residential building
with separate circuits for lights and fans and for power
appliances is given in Fig. 1.
5.10 For detailed information regarding the installation
of different electrical equipments, reference may be
made to good practice [8-2(17)].
5A SWITCH
SOCKET OUTLET
DISTRIBUTION BOARD
FOR THE FLAT
15A SWITCH
SOCKET OUTLET
Fig. 1 Wiring Diagram for a Typical Distribution Board Scheme
in a Residential Building Flat
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
27
6 WIRING
6.1 Provision for Maximum Load
All conductors, switches and accessories shall be of
such size as to be capable of carrying, without their
respective ratings being exceeded, the maximum
current which will normally flow through them.
6,1.1 Estimation of Load Requirements
In estimating the current to be carried by any conductor
the following ratings shall be taken, unless the actual
values are known or specified for these elements:
Element
Rating (in W)
Incandescent lamps
60
Ceiling fans \
Table fans J
100
i \j\j
Ordinary socket outlet points
100
Fluorescent tubes:
Length: 600 mm
25
1200 mm
50
1 500 mm
90
Power socket-outlet
1000
Air-conditioner
2 500
6.1.2 Electrical installation in a new building shall
normally begin immediately on the completion of the
main structural building work and before finishing
work such as plastering has begun except in the case
of surface wiring which can be carried out after the
plaster work. Usually, no installation work should start
until the building is reasonably weatherproof, but
where electric wiring is to be concealed within the
structures as may be the case with a reinforced concrete
building, the necessary conduits and ducts shall be
positioned firmly by tying the conduit to the
reinforcement before concreting. When shutters are
removed after concreting, the conduits ends shall be
given suitable anti-corrosive treatment and holes
blocked off by putties or caps to protect conduits from
getting blocked. All conduit openings and junction box
openings, etc shall be properly protected against entry
of mortar, concrete, etc during construction.
6.2 Selection of Size of Conductors
The size of conductors of circuits shall be so selected
that the drop in voltage from consumer's terminals in
a public supply (or from the busbars of the main
switchboard controlling the various circuits in a private
generation plant) to any point on the installation does
not exceed three percent of the voltage at the
consumer' s terminals (or at two busbars as these may
be) when the conductors are carrying the maximum
current under the normal conditions of service.
6.2.1 If the cable size is increased to avoid voltage
drop in the circuit, the rating of the cable shall be the
current which the circuit is designed to carry. In each
circuit or sub-circuit the fuse shall be selected to match
the cable rating to ensure the desired protection.
6.3 Branch Switches
Where the supply is derived from a three- wire or four-
wire source, and distribution is done on the two-wire
system, all branch switches shall be placed in the outer
or live conductor of the circuit and no single phase
switch or protective device shall be inserted in the
middle wire, earth or earthed neutral conductor of the
circuit. Single-pole switches (other than for multiple
control) carrying not more than 1 6 A may be of tumbler
type or flush type which shall be on when the handle
or knob is down.
6.4 Layout and Installation Drawing
6.4.1 The electrical layout should be drawn indicating
properly the locations of all outlets for lamps, fans,
appliances both fixed and transportable, motors, etc,
and best suit for wiring.
6.4.2 All runs of wiring and the exact positions of all
points of switch-boxes and other outlets shall be first
marked on the plans of the building and approved by
the engineer-in-charge or the owner before actual
commencement of the work.
6.4.3 Industrial layout drawings should indicate the
relative civil and mechanical details.
6.4.4 Layout of Wiring
The layout of wiring should be designed keeping in
view disposition of the lighting system to meet the
illumination levels. All wirings shall be done on the
distribution system with main and branch distribution
boards at convenient physical and electrical load
centres. All types of wiring, whether concealed or
unconcealed should be as near the ceiling as possible.
In all types of wirings due consideration shall be given
for neatness and good appearance.
6.4.5 Balancing of circuits in three-wire or poly-phase
installation shall be arranged before hand. Proper
Balancing can be done, only under actual load
conditions. Conductors shall be so enclosed in earthed
metal or incombustible insulating material that it is not
possible to have ready access to them. Means of access
shall be marked to indicate the voltage present.
Where terminals or other fixed live parts between
which a voltage exceeding 250 V exists are housed in
separate enclosures or items of apparatus which,
although separated are within reach of each other, a
notice shall be placed in such a position that anyone
gaining access to live parts is warned of the magnitude
of the voltage that exists between them.
28
NATIONAL BUILDING CODE OF INDIA
Where loads are single phase, balancing should be for
the peak load condition based on equipment usage.
Facility for change should be built into the distribution
design.
NOTE — The above requirements apply equally to three-phase
circuits in which the voltage between lines or to earth exceeds
250 V and to groups of two or more single-phase circuits,
between which medium voltage may be present, derived
therefrom. They apply also to 3-wire dc or 3-wire single-phase
ac circuits in which the voltage between lines or to earth
exceeds 250 V and to groups of 2-wire circuits, between which
medium voltage may be present, derived therefrom.
6.4.6 Medium voltage wiring and associated apparatus
shall comply, in all respects, with the requirements of
Rules 50, 51 and 61 of the Indian Electricity Rules,
1956 as amended up-to-date.
6.5 Conductors and Accessories
6.5.1 Conductors
Conductors for all the internal wiring shall be of
copper. Conductors for power and lighting circuits shall
be of adequate size to carry the designed circuit load
without exceeding the permissible thermal limits for
the insulation. The conductor for final sub-circuit for
fan and light wiring shall have a nominal cross-
sectional area not less than 1.50 mm 2 copper. The
cross-sectional area of conductor for power wiring shall
be not less than 4.0 mm 2 copper. The minimum cross-
sectional area of conductor of flexible cord shall be
1.50 mm 2 copper.
In existing buildings where aluminium wiring has been
used for internal electrification, changeover from
aluminium conductor to copper conductor may be
made once the former goes beyond economical repairs.
NOTE — It is advisable to replace wiring, which is more than
30 years old as the insulation also would have deteriorated,
and will be in a state to cause failure on the slightest of
mechanical or electrical disturbance.
6.5.2 Flexible Cables and Flexible Cords
Flexible cables and cords shall be of copper and
stranded and protected by flexible conduits or tough
rubber or PVC sheath to prevent mechanical damage.
6.5.3 Cable Ends
When a stranded conductor having a nominal sectional
area less than 6 mm 2 is not provided with cable sockets,
all strands at the exposed ends of the cable shall be
soldered together or crimped using suitable sleeve or
ferrules.
6.5.4 Special Risk
Special forms of construction, such as flameproof
enclosures, shall be adopted where there is risk of the
fire or explosion.
6.5.5 Connection to Ancillary Buildings
Unless otherwise specified, electric connections to
ancillary buildings, such as out-houses, garages, etc,
adjacent to the main building and when no roadway
intervenes shall be taken in an earthed GI pipe or heavy
duty PVC or HDPE pipe of suitable size in the exposed
portion at a height of not less than 5.8 m or by buried
underground cables. This applies to both runs of mains
or sub-mains or final sub-circuit wiring between the
buildings.
6.5.6 Expansion Joints
Distribution boards shall be so located that the conduits
shall not normally be required to cross expansion joints
in a building. Where such crossing is found to be
unavoidable, special care shall be taken to ensure that
the conduit runs and wiring are not in any way put to
strain or damaged due to expansion of building
structure. Anyone of the standard methods of
connection at a structural expansion joint shall be
followed:
a) Flexible conduit shall be inserted at place of
expansion joint.
b) Oversized conduit overlapping the conduit.
c) Expansion box.
6.5.7 Low Voltage (Types of Wires/Cables)
Low voltage services utilizes various categories of
cables/wires, such as Fibre optic cable, co-axial,
CAT 5, etc. These shall be laid at atleast minimum
specified distance of 300 mm from any power wire or
cable. Special care shall be taken to ensure that the
conduit runs and wiring are laid properly for low
voltage signal to flow through it.
6.6 Joints and Looping Back
6.6.1 Where looping back system of wiring is
specified, the wiring shall be done without any junction
or connector boxes on the line. Where joint box system
is specified, all joints in conductors shall be made by
means of suitable mechanical connectors in suitable
joint boxes. Wherever practicable, looping back system
should be preferred. Whenever practicable, only one
system shall be adopted for a building, preferably a
looping back system.
6.6.2 In any system of wiring, no bare or twist joints
shall be made at intermediate points in the through run
of cables unless the length of a final sub-circuit, sub-
main or main or more than the length of the standard
coil as given by the manufacturer of the cable. If any
jointing becomes unavoidable such joint shall be made
through proper cutouts or through proper junction
boxes open to easy inspection, but in looping back
system no such junction boxes shall be allowed.
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
29
6.6.3 Joints are a source of problems in reliability and
are also vulnerable to fire. They should be avoided or
at least minimized. Where joints in cable conductors
or bare conductors are necessary, they shall be
mechanically and electrically sound. Joints in non-
flexible cables shall be accessible for inspection;
provided that this requirement shall not apply to joints
in cables buried underground, or joints buried or
enclosed in non-combustible building materials. Joints
in non-flexible cables shall be made by soldering,
brazing, welding or mechanical clamps, or be of the
compression type; provided that mechanical clamps
shall not be used for inaccessible joints buried or
enclosed in the building structure. All mechanical
clamps and compression type sockets shall securely
retain all the wires of the conductors. Any joint in a
flexible cable of flexible cord shall be effected by
means of a cable coupler.
For flexible cables for small loads less than 1 kW, while
it would be desirable to avoid joints, if unavoidable,
joints can be made either by splicing by a recognised
method or by using a connector and protecting the joint
by suitable insulating tape or sleeve or straight joint.
For application of flexible cable for loads of 1 kW or
more, if joint is unavoidable, crimped joint would be
preferred. Spliced joint should not be used for large
loads.
There are different standard joints such as epoxy resin
based joint, heat shrinkable plastic sleeve joint etc, and
each one has its advantage and disadvantage. Selection
has to be made on the basis of application, site
conditions and availability of skilled licensed
workmen.
6.6.4 Every joint in a cable shall be provided with
insulation not less effective than that of the cable cores
and shall be protected against moisture and mechanical
damage. Soldering fluxes which remain acidic or
corrosive at the completion of the soldering operation
shall not be used.
For joints in paper-insulated metal-sheathed cables, a
wiped metal sleeve or joint box, filled with insulating
compound, shall be provided.
Where an aluminium conductor and a copper conductor
are joined together, precautions shall be taken against
corrosion and mechanical damage to the conductors.
6.6.5 Pull at Joints and Terminals
Every connection at a cable termination shall be
made by means of a terminal, soldering socket, or
compression type socket and shall securely contain and
anchor all the wires of the conductor, and shall not
impose any appreciable mechanical strain on the
terminal or socket.
Flexible cords shall be so connected to devices and to
fittings that tension will not be transmitted to joints or
terminal screws. This shall be accomplished by a knot
in the cord, by winding with tape, by a special fitting
designed for that purpose, or by other approved means
which will prevent a pull on the cord from being
directly transmitted to joints or terminal screws.
6.7 Passing Through Walls and Floors
6.7.1 Where conductors pass through walls, one of the
following methods shall be employed. Care shall be
taken to see that wires pass freely through protective
pipe or box and that the wires pass through in a straight
line without any twist or cross in wires on either ends
of such holes:
a) The conductor shall be carried either in a rigid
steel conduit or a rigid non-metallic conduit
conforming to accepted standards [8-2(18)].
b) Conduit colour coding
The conduits shall be colour coded as per the
purpose of wire carried in the same. The
colour coding may be in form of bands of
colour (4 inch thick, with centre-to-centre
distance of 12 inches) or coloured throughout
in the colour. The colour scheme shall be as
follows:
Conduit Type Colour scheme
Power conduit Black
Security conduit Blue
Fire alarm conduit Red
Low voltage conduit Brown
UPS conduit Green
c) Cable trunking/ cable ways
For the smaller cables, enclosures such as
conduit and trunking, may be employed and
PVC-insulated, with or without sheath, single-
core cables installed following completion of
the conduit/trunking system. As these cables
are usually installed in relatively large groups,
care must be taken to avoid overheating and
to provide identification of the different
circuits.
d) Tray and ladder rack
As tray provides continuous support, unless
mounted on edge or in vertical runs (when
adequate strapping or clipping is essential),
the mechanical strength of supported cable is
not as important as with ladder-racking or
structural support methods. Consequently,
tray is eminently suitable for the smaller
unarmoured cabling while racks and
structural support, except for short lengths,
call for armoured cables as they provide the
necessary strength to avoid sagging between
30
NATIONAL BUILDING CODE OF INDIA
supports. Both tray and ladder racks can be
provided with accessories to facilitate changes
of route, and as PVC and similar insulating
materials are non-migratory (unlike the older
types of impregnated cables) they provide no
difficulty in this respect on vertical runs.
e) Insulated conductors while passing through
floors shall be protected from mechanical
injury by means of rigid steel conduit, non-
metal conduit or mechanical protection to a
height not less than 1.5 m above the floors
and flush with the ceiling below. This steel
conduit shall be earthed and securely bushed.
Power outlets and wiring in the floor shall be
generally avoided. If not avoidable, use false
floor or floor trunking. False floor shall be
provided where density of equipment and
interconnection between different pieces of
equipment is high. Examples are: Mainframe
Computer station, Telecommunication switch
rooms, etc.
Floor trunking shall be used in large halls,
convention centres, open plan offices,
laboratory, etc.
In case of floor trunking drain points shall be
provided, as there could be possibility of
water seepage in the case of wiring passing
through the floors. Proper care should be
taken for suitable means of draining of water.
Possibility of water entry exists from: ( 1 ) floor
washing, (2) condensation in some particular
weather and indoor temperature conditions.
At the design stage, these aspects have to be
assessed and an appropriate means of
avoiding, or reducing, and draining method
will have to be built in.
Floor outlet boxes are generally provided for
the use of appliances, which require a signal,
or communication connection. The floor box
and trunking system should cater to serve both
power distribution and the signal distribution,
with appropriate safety and non-interference.
6.7.2 Where a wall tube passes outside a building so
as to be exposed to weather, the outer end shall be
bell-mouthed and turned downwards and properly
bushed on the open end.
6.8 Wiring of Distribution Boards
6.8.1 All connections between pieces of apparatus or
between apparatus and terminals on a board shall be
neatly arranged in a definite sequence, following the
arrangements of the apparatus mounted thereon,
avoiding unnecessary crossings.
6.8.2 Cables shall be connected to a terminal only by
soldered or welded or crimped lugs using suitable
sleeve, lugs or ferrules unless the terminal is of such a
form that it is possible to securely clamp them without
the cutting away of cables stands. Cables in each circuit
shall be bunched together.
6.8.3 All bare conductors shall be rigidly fixed in such
a manner that a clearance of at least 25 mm is
maintained between conductors or opposite polarity
or phase and between the conductors and any material
other than insulation material.
6.8.4 If required, a pilot lamp shall be fixed and
connected through an independent single pole switch
and fuse to the bus-bars of the board.
6.8.5 In a hinged type board, the incoming and
outgoing cables shall be fixed at one or more points
according to the number of cables on the back of the
board leaving suitable space in between cables, and
shall also, if possible, be fixed at the corresponding
points on the switchboard panel. The cables between
these points shall be of such length as to allow the
switchboard panel to swing through on angle of not
less than 90°. The circuit breakers in such cases shall
be accessible without opening the door of distribution
board. Also, circuit breakers or any other equipment
(having cable size more than 1.5 sq. mm multistrand
wire) shall not be mounted on the door.
NOTE — Use of hinged type boards is discouraged, as these
boards lead to deterioration of the cables in the hinged portion,
leading to failures or even fire.
6.8.6 Wires terminating and originating from the
protective devices shall be properly lugged and taped.
6.9 PVC-Sheathed Wiring System
6.9.1 General
Wiring with Tough Rubber-Sheathed (TRS) cables had
been the common system for low voltage installations.
Now TRS wiring is phased out as better and durable
insulating materials are available.
Wiring with PVC-sheathed cables is suitable for
medium voltage installation and may be installed
directly under exposed conditions of sun and rain or
damp places.
6.9.2 PVC Clamps/PVC Channel
Link clips had been the common system for wiring on
wooden batten, which is now phased out. PVC clamps/
PVC channel shall conform accepted standards. The
clamps shall be used for temporary installations of 1-3
sheathed wires only. The clamps shall be fixed on wall
at intervals of 100 mm in the case of horizontal runs
and 150 mm in the case of vertical runs.
PVC channel shall be used for temporary installations
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
31
in case more than 3 wires or wires or unsheathed wires.
The channel shall be clamped on wall at intervals not
exceeding 300 mm.
6.9.3 Protection of PVC-Sheathed Wiring from
Mechanical Damage
a) In cases where there are chances of any
damage to the wirings, such wirings shall be
covered with sheet metal protective covering,
the base of which is made flush with the
plaster or brickwork, as the case may be, or
the wiring shall be drawn through a conduit
complying with all requirements of conduit
wiring system (see 6.10).
b) Such protective coverings shall in all cases
be fitted on all down-drops within 1.5 m from
the floor.
6.9.4 Bends in Wiring
The wiring shall not in any circumstances be bent so
as to form a right angle but shall be rounded off at the
corners to a radius not less than six times the overall
diameter of the cable.
6.9.5 Passing Through Floors
All cables taken through floors shall be enclosed in an
insulated heavy gauge steel conduit extending 1.5 m
above the floor and flush with the ceiling below, or by
means of any other approved type of metallic covering.
The ends of all conduits or pipes shall be neatly bushed
with porcelain, wood or other approved material.
6.9.6 Passing Through Walls
The method to be adopted shall be according to good
practice. There shall be one or more conduits of
adequate size to carry the conductors [see 6.10.1(a)].
The conduits shall be neatly arranged so that the cables
enter them straight without bending.
6.9.7 Stripping of Outer Covering
While cutting and stripping of the outer covering of
the cables, care shall be taken that the sharp edge of
the cutting instrument does not touch the rubber or
PVC-sheathed insulation of conductors. The protective
outer covering of the cables shall be stripped off near
connecting terminals, and this protective covering shall
be maintained up to the close proximity of connecting
terminals as far as practicable. Care shall be taken to
avoid hammering on link clips with any metal
instruments, after the cables are laid. Where junction
boxes are provided, they shall be made moisture-proof
with an approved plastic compound.
6.9.8 Painting
If so required, the tough rubber-sheathed wiring shall,
after erection, be painted with one coat of oil-less paint
or distemper of suitable colour over a coat of oil-less
primer, and the PVC-sheathed wiring shall be painted
with a synthetic enamel paint of quick drying type.
6.10 Conduit Wiring System
6.10.1 Surface Conduit Wiring System with Rigid Steel
Conduits
a) Type and size of conduit — All conduit pipes
shall conform to accepted standards [8-2(19)],
finished with galvanized or stove enamelled
surface. All conduit accessories shall be of
threaded type and under no circumstance pin
grip type or clamp type accessories be used.
No steel conduit less than 16 mm in diameter
shall be used. The number of insulated
conductors that can be drawn into rigid
conduit are given in Tables 1 and 2.
b) Bunching of cables — Unless otherwise
specified, insulated conductors of ac supply
and dc supply shall be bunched in separate
conduits. For lighting and small power outlet
circuits phase egregation in separate conduits
is recommended.
c) Conduit joints — Conduit pipes shall be
joined by means of screwed couplers and
screwed accessories only [see 8-2(19)]. In
long distance straight runs of conduit,
inspection type couplers at reasonable
intervals shall be provided or running threads
with couplers and jam-nuts (in the latter case
the bare threaded portion shall be treated with
anti-corrosive preservative) shall be provided.
Threaded on conduit pipes in all cases shall
be between 1 1 mm to 27 mm long sufficient
to accommodate pipes to full threaded portion
of couplers or accessories. Cut ends of conduit
pipes shall have no sharp edges nor any burrs
left to avoid damage to the insulation of
conductors while pulling them through such
pipes.
d) Protection against dampness — In order to
minimize condensation or sweating inside the
tube, all outlets of conduit system shall be
properly drained and ventilated, but in such a
manner as to prevent the entry of insects as
far as possible.
e) Protection of conduit against rust — The
outer surface of the conduit pipes, including
all bends, unions, tees, conduit system shall be
adequately protected against rust particularly
when such system is exposed to weather. In
all cases, no bare threaded portion of conduit
pipe shall be allowed unless such bare
threaded portion is treated with anti-corrosive
32
NATIONAL BUILDING CODE OF INDIA
Table 1 Maximum Permissible Number of Single-Core Cables up to and Including 1 100 V that
can be Drawn into Rigid Steel and Rigid Non-Metallic Conduits
(ClmmPX 6 10 1 and fi 1 ^ T>
Size of Cable
Sectional Area
2
mm
U)
meter (in mm)
of Wires
V)
S
(3)
B
(4)
S
(5)
B
(6)
S
(7)
Size of Conduit (mm)
: io ac\ <r\ &r\
I J±* TV/ ^\* "V
(Number of Cables. Max)
BSBSBSBSB
(8) (9) (10) (11) (12) (13) (14) (15) (16)
10 20 14 — — — — — —
10 20 14 — — — — — —
8 18 12 — — — — — —
8 12 10 — — — — — —
5 10 8 _______ —
3 6 5 8 6 — — — —
— 43 7 6 — — — —
— 32548697
— 2 — 437586
1.0
1.5
2.5
1/1.12 1 '
1/1.40
i/i.SG
3/L06 1 '
1/2.24
7/0.85 1 *
1/2.80
7/1.40°
7/1.70
7/2.24
7/2.50
19/1.80
4 7
3 7
2
2 4
— 3
?
13
12
10
10
16
25
35
50
NOTES
1 The table shows the maximum capacity of conduits for the simultaneously drawing of cables. The columns headed S apply to runs
of conduit which have distance not exceeding 4.25 m between draw-in boxes, and which do not deflect from the straight by an angle of
cnas^tinn hma *l*vmr_im V\s\v Kif kaan i-MvwiHnH i«H if tK*a i-aMfs if fire* /Jraiyn tVirralCTfl r\nt± StT_i ht COfidUit thCfl thjTOU a h
the draw-in box, and then through the second straight conduit, such systems may be considered as that of a straight conduit even if the
conduit deflects through the straight by more than 15°.
Table 2 Maximum Permissible Number of Single-Core Cables that can be Drawn into
Cable Tunelling and Ducting System (Casing and Capping)
(Clauses 6.10.1 and 6.103.2)
en „» ....
rNominai ^ross-
ww 13 mm x
l\3 mm x
x:j mm x
JV 11UU A
tu nun a
JV IIUII ^
Sectional Area of
10 mm
10 mm
10 mm
10 mm
20 mm
20 mm
Conductor in mm
(1)
(2)
(3)
(4)
(5)
(6)
(7)
1.5
3
5
6
8
12
18
2.5
2
4
5
6
9
15
4
2
3
4
5
8
12
6
—
2
3
4
6
9
10
—
1
2
3
5
8
16
—
—
i
z
t
o
j
1
<
z,j
A
-/
35
—
—
—
2
4
50
—
—
—
—
1
3
70
~
—
—
—
I
2
preservative or covered with suitable plastic
compound,
f) Fixing of conduit — Conduit pipes shall be
fixed by heavy gauge saddles, secured to
suitable wood plugs or other plugs with
screws in an approved manner at an interval
g)
of not more than 1 m, but on either side of
couplers or bends or similar fittings, saddles
shall be fixed at a distance of 300 cm from
the centre of such fittings.
Bends in conduit — All necessary bends in
the system including diversion shall be done
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
33
by bending pipes; or by inserting suitable
solid or inspection type normal bends, elbows
or similar fittings; or fixing cast iron,
thermoplastic or thermosetting plastic
material inspection boxes whichever is more
suitable. Conduit fittings shall be avoided as
far as possible on conduit system exposed to
weather; where necessary, solid type fittings
shall be used. Radius of such bends in conduit
pipes shall be not less than 7.5 cm. No length
of conduit shall have more than the equivalent
of four quarter bends from outlet to outlet,
the bends at the outlets not being counted.
h) Outlets — All outlets for fittings, switches,
etc, shall be boxes of suitable metal or any
other approved outlet boxes for either surface
mounting system.
j) Conductors — All conductors used in conduit
wiring shall preferably be stranded. No single-
core cable of nominal cross-sectional area
greater than 130 mm 2 enclosed along in a
conduit and used for alternating current.
k) Erection and earthing of conduit — The
conduit of each circuit or section shall be
completed before conductors are drawn in.
The entire system of conduit after erection
shall be tested for mechanical and electrical
continuity throughout and permanently
connected to earth conforming to the
requirements as already specified by means
of suitable earthing clamp efficiently fastened
to conduit pipe in a workman like manner for
a perfect continuity between each wire and
conduit. Gas or water pipes shall not be used
as earth medium. If conduit pipes are liable
to mechanical damage they shall be adequately
protected.
m) Inspection type conduit fittings, such as
inspection boxes, draw boxes, bends, elbows
and tees shall be so installed that they can
remain accessible for such purposes as to
withdrawal of existing cables or the installing
of traditional cables.
6.10.2 Recessed Conduit Wiring System with Rigid
Steel Conduit
Recessed conduit wiring system shall comply with all
the requirements for surface conduit wiring system
specified in 6.10.1 (a) to (k) and in addition, conform
to the requirements specified below:
a) Making of chase — The chase in the wall shall
be nearly made and be of ample dimensions
to permit the conduit to be fixed in the manner
desired. In the case of buildings under
construction, chases shall be provided in the
wall, ceiling, etc, at the time of their
construction and shall be filled up neatly after
erection of conduit and brought to the original
finish of the wall. In case of exposed brick/
rubble masonry work, special care shall be
taken to fix the conduit and accessories in
position along with the building work.
b) Fixing of conduit in chase — The conduit pipe
shall be fixed by means of staples or by means
of saddles not more than 600 mm apart.
Fixing of standard bends or elbows shall be
avoided as far as practicable and all curves
maintained by bending the conduit pipe itself
with a long radius which will permit easy
drawing-in of conductors. All threaded joints
of rigid steel conduit shall be treated with
preservative compound to secure protection
against rust.
c) Inspection boxes — Suitable inspection boxes
shall be provided to permit periodical
inspection and to facilitate removal of wires,
if necessary. These shall be mounted flush
with the wall. Suitable ventilating holes shall
be provided in the inspection box covers. The
minimum sizes of inspection boxes shall be
75 mm x 75 mm.
d) Types of accessories to be used — All outlet,
such as switches and wall sockets, may be
either of flush mounting type or of surface
mounting type.
1) Flush mounting type — All flush
mounting outlets shall be of cast-iron
or mild steel boxes with a cover of
insulating material or shall be a box made
of a suitable insulating material. The
switches and other outlets shall be
mounted on such boxes. The metal
box shall be efficiently earthed with
conduit by a suitable means of earth
attachment.
2) The switches/socket outlets shall
be adequately rated IP for various
utilizations.
3) Surface mounting type — If surface
mounting type otulet box is specified, it
shall be of any suitable insulating
material and outlets mounted in an
approved manner.
6.10.3 Conduit Wiring System with Rigid Non-Metallic
Conduits
Rigid non-metallic conduits are used for surface,
recessed and concealed conduit wiring. Cable trunking
and ducting system of insulating material are used for
surface wiring.
34
NATIONAL BUILDING CODE OF INDIA
6.10.3.1 Type and size
All non-metallic conduits used shall conform to
accepted standards [8-2(19)]. The conduit may be
either threaded type or plain type in accordance with
accepted standards [8-2(19)] and shall be used with
the corresponding accessories { see accepted standards
[8-2( 19)] } . The conduits shall be circular or rectangular
cross-sections.
6.10.3.2 Bunching of cables
Conductors of ac supply and dc supply shall be
bunched in separate conduits. For lighting and small
power outlet circuits phase segregation in separate
circuits is recommended. The number of insulated
cables that may be drawn into the conduits are given
in Table 1 and Table 2. In these tables the space factor
does not exceed 40 percent.
6.10.3.3 Conduit joints
Conduits shall be joined by means of screwed or plain
couplers depending on whether the conduits are
screwed or plain. Where there are long runs of straight
conduit, inspection type couplers shall be provided at
intervals. For conduit fittings and accessories reference
may be made to the good practice [8-2(19)].
6.10.3.4 Fixing of conduits
The provisions of 6.10.1(f) shall apply except that the
spacing between saddles or supports is recommended
to be 600 cm for rigid non-metallic conduits.
6.10.3.5 Bends in conduits
Wherever necessary, bends or diversions may be
achieved by bending the conduits {see 6.10.3.8) or by
employing normal bends, inspection bends, inspection
boxes, elbows or similar fittings.
6.10.3.6 Conduit fittings shall be avoided, as far as
possible, on outdoor systems.
6.10.3.7 Outlets
In order to minimize condensation or sweating inside
the conduit, all outlets of conduit system shall be
properly drained and ventilated, but in such a manner
as to prevent the entry of insects.
6.10.3.8 Heat may be used to soften the conduit for
bending and forming joints in case of plain conduits.
As the material softens when heated, sitting of conduit
in close proximity to hot surfaces should be avoided.
Caution should be exercised in the use of this conduit
in locations where the ambient temperature is 50°C
or above. Use of such conduits in places where
ambient temperature is 60°C or above is prohibited.
6.10.3.9 Non-metallic conduit systems shall be used
only where it is ensured that they are:
a) suitable for the extremes of ambient
temperature to which they are likely to be
subjected in service,
b) resistant to moisture and chemical
atmospheres, and
c) resistant to low temperature and sunlight
effects.
For use underground, the material shall be resistant to
moisture and corrosive agents.
NOTE — Rigid PVC conduits are not suitable for use where
the normal working temperature of the conduits and fittings
may exceed 55°C. Certain types of rigid PVC conduits and
their associated fittings are unsuitable for use where the ambient
temperature is likely to fall below -5°C.
6.10.4 Non-Metallic Recessed Conduit Wiring
System
6.10.4.1 Recessed non-metallic conduit wiring system
shall comply with all the requirements of surface non-
metallic conduit wiring system specified in 6.10.3.1
to 6.10.3.9 except 6.10.3.4. In addition, the following
requirements 6.10.4.2 to 6.10.4.5 also shall be
complied with.
6.10.4.2 Fixing of conduit in chase
The conduit pipe shall be fixed by means of stapples
or by means of non-metallic saddles placed at not more
than 80 cm apart or by any other approved means of
fixing. Fixing of standard bends or elbows shall be
avoided as far as practicable and all curves shall be
maintained by sending the conduit pipe itself with a
long radius which will permit easy drawing in of
conductors. At either side of bends, saddles/stapples
shall be fixed at a distance of 15 cm from the centre of
bends.
6.10.4.3 Inspection boxes
Suitable inspection boxes to the nearest minimum
requirements shall be provided to permit periodical
inspection and to facilitate replacement of wires, if
necessary. The inspection/junction boxes shall be
mounted flush with the wall or ceiling concrete. Where
necessary deeper boxes of suitable dimensions shall
be used. Suitable ventilating holes shall be provided
in the inspection box covers, where required.
6.10.4.4 The outlet boxes such as switch boxes,
regulator boxes and their phenolic laminated sheet
covers shall be as per requirements of 6.10.1(h).
They shall be mounted flush with the wall.
6.10.4.5 Types of accessories to be used
All outlets such as switches, wall sockets, etc, may
be either flush mounting type or of surface mounting
type.
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
35
7 FITTINGS AND ACCESSORIES
7.1 Ceiling Roses and Similar Attachments
7.1.1 A ceiling rose or any other similar attachment
shall not be used on a circuit the voltage of which
normally exceeds 250 V.
7.1.2 Normally, only one flexible cord shall be
attached to a ceiling rose. Specially designed ceiling
roses shall be used for multiple pendants.
7.1.3 A ceiling rose shall not embody fuse terminal
as an integral part of it.
7.2 Socket-Outlets and Plugs
Each 16 A socket-outlet provided in buildings for the
use of domestic appliances such as air conditioner,
water cooler, etc, shall be provided with its own
individual fuse, with suitable discrimination with back-
up fuse or miniature circuit-breaker provided in the
distribution/sub-distribution board. The socket-outlet
shall not necessarily embody the fuse as an integral
part of it.
7.2.1 Each socket-outlet shall also be controlled by a
switch which shall preferably be located immediately
adjacent thereto or combined therewith.
7.2.2 The switch controlling the socket-outlet shall be
on the live side of the line.
7.2.3 Ordinary socket-outlet may be fixed at any
convenient place at a height above 20 cm from the
floor level and shall be away from danger of
mechanical injury.
NOTE — In situations where a socket-outlet is accessible to
children, it is necessary to install an interlocked plug and socket
or alternatively a socket-outlet which automatically gets
screened by the withdrawal of plug. In industrial premises
socket-outlet of rating 20 A and above shall preferably be
provided with interlocked type switch.
7.2.4 In an earthed system of supply, a socket-outlet
with plug shall be of three-pin type with the third
terminal connected to the earth. When such socket-
outlets with plugs are connected to any current
consuming device of metal or any non-insulating
material or both, conductors connecting such current-
consuming devices shall be of flexible cord with an
earthing core and the earthing core shall be secured by
connecting between the earth terminal of plug and the
body of current-consuming devices.
In industrial premises three-phase and neutral socket-
outlets shall be provided with a earth terminal either
of pin type or scrapping type in addition to the main
pins required for the purpose.
7.2.5 In wiring installations, metal clad switch, socket-
outlet and plugs shall be used for power wiring.
NOTE — A recommended schedule of socket-outlets in
residential building is given below:
location
Number of 5 A
Socket-Outlets
Number of 15A
Socket-Outlets
Bedroom
2 to 3
1
Living room
Kitchen
2 to 3
1
2
2
Dining room
Garage
For refrigerator
For air conditioner
2
1
1
1
1
(one for each)
VERANDAH
Bathroom
1 per 10 m
1
1
1
7.3 Lighting Fittings
7.3.1 A switch shall be provided for control of every
lighting fitting or a group of lighting fittings. Where
control at more than one point is necessary as many
two way or intermediate switches may be provided as
there are control points.
7.3.2 In industrial premises lighting fittings shall be
supported by suitable pipe/conduits, brackets fabricated
from structural steel, steel chains or similar materials
depending upon the type and weight of the fittings.
Where a lighting fitting is supported by one or more
flexible cords, the maximum weight to which the twin
flexible cords may be subjected shall be as follows:
Nominal Cross-Sectional
Maximum
Area of Twin
Cord
Permissible Weight
mm 2
kg
0.5
2
0.75
3
1.0
5
1.5
5.3
2.5
8.8
4
14.0
7.3.3 No flammable shade shall form a part of lighting
fittings unless such shade is well protected against all
risks of fire. Celluloid shade or lighting fittings shall
not be used under any circumstances.
7.3.4 General and safety requirements for electrical
lighting fittings shall be in accordance with good
practice [8-2(20)].
7.3.5 The lighting fittings shall conform to accepted
standards [8-2(10)].
7.4 Fitting-Wire
The use of fittings- wire shall be restricted to the internal
wiring of the lighting fittings. Where fittings-wire is
used for wiring fittings, the sub-circuit loads shall
terminate in a ceiling rose or box with connectors from
which they shall be carried into the fittings.
36
NATIONAL BUILDING CODE OF INDIA
7.5 Lampholders
Lampholders for use on brackets and the like shall be
in accordance with accepted standards [8-2(21)] and
all those for use with flexible pendants shall be
provided with cord grips. All lampholders shall be
provided with shade carriers. Where centre-contact
Edison screw lampholders are used, the outer or screw
contacts shall be connected to the 'middle wire', the
neutral, the earthed conductor of the circuit.
7.6 Outdoor Lamps
External and road lamps shall have weatherproof
fittings of approved design so as to effectively prevent
the ingress of moisture and dust. Flexible cord and cord
grip lampholders shall not be used where exposed to
weather. In VERANDAHS and similar exposed
situations where pendants are used, these shall be of
fixed rod type.
7.7 Lamps
All lamps unless otherwise required and suitably
protected, shall be hung at a height of not less than
2.5 m above the floor level. All electric lamps and
accessories shall conform to accepted standards
[8-2(22)].
a) Portable lamps shall be wired with flexible
cord. Hand lamps shall be equipped with a
handle of moulded composition or other
material approved for the purpose. Hand
lamps shall be equipped with a substantial
guard attached to the lampholder or handle.
Metallic guards shall be earthed suitably.
b) A bushing or the equivalent shall be provided
where flexible cord enters the base or stem of
portable lamp. The bushing shall be of
insulating material unless a jacketted type of
cord is used.
c) All wiring shall be free from short-circuits and
shall be tested for these defects prior to being
connected to the circuit.
d) Exposed live parts within porcelain fixtures
shall be suitably recessed and so located as to
make it improbable that wires will come in
contact with them. There shall be a spacing
of at least 125 mm between live parts and the
mounting plane of the fixture.
7.8 Fans, Regulators and Clamps
7.8.1 Ceiling Fans
Ceiling fans including their suspension shall conform
to accepted standards [8-2(23)] and to the following
requirements:
a) Control of a ceiling fan shall be through
its own regulator as well as a switch in
series.
b) All ceiling fans shall be wired with normal
wiring to ceiling roses or to special connector
boxes to which fan rod wires shall be
connected and suspended from hooks or
shackels with insulators between hooks and
suspension rods. There shall be no joint in the
suspension rod, but if joints are unavoidable
then such joints shall be screwed to special
couplers of 5 cm minimum length and both
ends of the pipes shall touch together within
the couplers, and shall in addition be secured
by means of split pins; alternatively, the two
pipes may be welded. The suspension rod
shall be of adequate strength to withstand the
dead and impact forces imposed on it.
Suspension rods should preferably be
procured along with the fan.
c) Fan clamps shall be of suitable design
according to the nature of construction of
ceiling on which these clamps are to be fitted.
In all cases fan clamps shall be fabricated from
new metal of suitable sizes and they shall be
as close fitting as possible. Fan clamps for
reinforced concrete roofs shall be buried with
the casting and due care shall be taken that
they shall serve the purpose. Fan clamps for
wooden beams, shall be of suitable flat iron
fixed on two sides of the beam and according
to the size and section of the beam one or two
mild steel bolts passing through the beam shall
hold both flat irons together. Fan clamps for
steel joist shall be fabricated from flat iron to
fit rigidly to the bottom flange of the beam.
Care shall be taken during fabrication that the
metal does not crack while hammer to shape.
Other fan clamps shall be made to suit the
position, but in all cases care shall be taken
to see that they are rigid and safe.
d) Canopies on top and bottom of suspension
rods shall effectively conceal suspensions and
connections to fan motors, respectively.
e) The lead-in-wire shall be of nominal cross-
sectional area not less than 1.5 mm 2 copper
and shall be protected from abrasion.
f) Unless otherwise specified, the clearance
between the bottom most point of the ceiling
fan and the floor shall be not less than 2.4 m.
The minimum clearance between the ceiling
and the plane of the blades shall be not less
than 300 mm.
A Typical arrangement of a fan clamp is given in Fig. 2.
NOTE — All fan clamps shall be so fabricated that fans revolve
steadily.
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
37
25 min.
EXPOSED LOOP
SHALL BE PAINTED
4—50
-100-
2B SLAB WITH BEAM
All dimensions in millimetres,
NOTES
1 RCC slab steel reinforcement not shown.
2 Fan clamp shall be placed in position such that its projecting arms in the line of length of beam.
Fig. 2 Typical Design of Fan Clamps
7.8.2 Exhaust tans
For fixing of an exhaust fan, a circular hole shall be
provided in the wall to suit the size of the frame which
shall be fixed by means of rag-bolts embedded in the
wall. The hole shall be neartly plastered with cement
and brought to the original finish of the wall. The
exhaust fan shall be connected to exhaust fan point
which shall be wired as near to the hole as possible by
means of a flexible cord, care being taken that the
blades rotate in the proper direction.
7.9 Attachment of Fittings and Accessories
7.9.1 In wiring other than conduit wiring, all ceiling
roses, brackets, pendants and accessories attached to
walls or ceilings shall be mounted on substantial teak
wood blocks twice varnished after all fixing holes are
made in them. Blocks shall not be less than 4 cm deep.
Brass screws shall only be used for attaching fittings
and accessories to their base blocks.
7.9.2 Where teak or hardwood boards are used for
mounting switches, regulators, etc, these boards shall
38
NATIONAL BUILDING CODE OF INDIA
be well varnished with pure shellac on all four sides
(both inside and outside), irrespective of being painted
to match the surroundings. The size of such boards
shall depend on the number of accessories that could
conveniently and neatly be arranged. Where there is
danger of attack by white ants, the boards shall be
treated with suitable anti-termite compount and painted
on both sides.
7.10 Interchangeably
Similar part of all switches, landholders, distribution
fuse-boards, ceiling roses, brackets, pendants, fans and
all other fittings shall be so chosen that they are of the
same type and interchangeable in each installation.
7.11 Equipment
Electrical equipment which form integral part of wiring
intended for switching or control or protection of
wiring installations shall conform to the relevant Indian
Standards wherever they exist.
7.12 Fannage
7.12.1 Where ceiling fans are provided, the bay sizes
of a building, which control fan point locations, play
an important part.
7.12.2 Fans normally cover an area of 9 m 2 to 10 m 2
and therefore in general purpose office buildings, for
every part of a bay to be served by the ceiling fans, it
is necessary that the bays shall be so designed that full
number of fans could be suitably located for the bay,
otherwise it will result in ill-ventilated pockets. In
general, fans in long halls may be spaced at 3 m in
both the directions. If building modules do not lend
themselves for proper positioning of the required
number of ceiling fans, such as air circulators or bracket
fans would have to be employed for the areas
uncovered by the ceiling fans. For this, suitable
electrical outlets shall be provided although result will
be disproportionate to cost on account of fans.
7.12.3 Proper air circulation could be achieved either
by larger number of smaller fans or smaller number of
larger fans. The economics of the system as a whole
should be a guiding factor in choosing the number and
type of fans and their locations.
7.12.4 Exhaust fans are necessary for spaces, such as
community toilets, kitchens and canteens, and godowns
to provide the required number of air changes {see
Part 8 'Building Services, Section 1 Lighting and
Ventilation'). Since the exhaust fans are located
generally on the outer walls of a room appropriate
openings in such walls shall be provided for in the
planning stage.
NOTE — Exhaust fan requirement is based on the recommended
air changes. Reference may also be made to Part 4 Tire and
Life Safety*. Exhaust fan requirement comes for catering to
smoke extraction also. Basement areas depend on the system
of fresh air fans and exhaust fans.
7.12.5 Positioning of fans and light fittings shall be
chosen to make these effective without causing
shadows and stroboscopic effect on the working planes.
8 EARTHING
8.1 General
Earthing shall generally be carried out in accordance
with the requirements of Indian Electricity Rules , 1956
as amended time to time and the relevant regulations
of the Electricity Supply Authority concerned.
The main earthing system of an electrical installation
must consist of:
a) An earth electrode;
b) A main earthing wire;
c) An earth bar (located on the main switchboard)
for the connection of the main earthing wire,
protective earthing wires and/or bonding
wires within the installation; and
d) A removable link, which effectively disconnects
the neutral bar from the earth bar.
NOTE — The requirements of (c) and (d) above must
be carried out by the licensed electrician as part of the
switchboard installation.
The main earthing wire termination must be readily
accessible at the earth electrode.
The main earthing wire connection must:
a) be mechanically and electrically sound;
b) be protected against damage, corrosion, and
vibration;
c) not place any strain on the various parts of
the connection;
d) not damage the wire or fittings; and
e) be secured at the earth electrode
Use a permanent fitting (like a screwed-down plastic
label or copper label, or one that can be threaded onto
the cable) at the connection pojnt that is clearly marked
with the words: "EARTHING LEAD — DO NOT
DISCONNECT" or "EARTHING CONDUCTOR —
DO NOT DISCONNECT".
8-1.1 All medium voltage equipment shall be earthed
by two separate and distinct connections with earth.
The contact area of earth conductor/plate shall be
determined using guidelines specified in IS 3043.
Medium voltage systems of 400/230 V, 4-wire,
3-phase, systems are normally operated with the neutral
solidly earthed at source. At medium voltage, Indian
Electricity Regulations require that the neutral be
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
39
earthed by two separate and distinct connections with
earth. Source in the case of a substation (such as 1 lkVY
400 V) would be the neutral(s) of the transformer(s).
Neutral conductor of half the size of the phase
conductor was permitted in earlier installations. But
with the proliferation of equipment using non-linear
devices and consequent increase in harmonics, the
neutral will carry a current more than the notional out-
of-balance current and as such neutral conductor shall
be of the same size as the phase conductor.
In the case of high and extra high voltages, the neutral
points shall be earthed by not less than two separate
and distinct connections with earth, each having
its own electrode at the generating station or
substation and may be earthed at any other point
provided no interference is caused by such earthing.
The neutral may be earthed through suitable
impedance. Neutral earthing conductor shall be sized
at to have a current carrying capacity not less than
the phase current.
8.1.2 As far as possible, all earth connections shall be
visible for inspection.
8.1.3 Earth earth system shall be so devised that the
testing of individual earth electrode is possible. It is
recommended that the value of any earth system
resistance shall be such as to conform with the degree
of shock protection desired.
8.1.4 It is recommended that a drawing showing the
main earth connection and earth electrodes be prepared
for each installation.
8.1.5 No addition to the current-carrying system, either
temporary or permanent, shall be made which will
increase the maximum available earth fault current or
its duration until it has been ascertained that the existing
arrangement of earth electrodes, earth busbar, etc, are
capable of carrying the new value of earth fault current
which may be obtained by this addition.
8.1.6 No cut-out, link or switch other than a linked
switch arranged to operate simultaneously on the
earthed or earthed neutral conductor and the live
conductors, shall be inserted on any supply system.
This, however, does not include the case of a switch
for use in controlling a generator or a transformer or a
link for test purposes.
8.1.7 All materials, fittings, etc, used in earthing shall
conform to Indian Standard specifications, wherever
these exist.
8.1.8 Earthing associated with current-carrying
conductor is normally essential for the security of the
system and is generally known as system earthing,
while earthing of non-current carrying metal work and
conductor is essential for the safety of human life, of
animals and of property and it is generally known as
equipment earthing.
8.2 Earth Electrodes
Earth electrode either in the form of pipe electrode or
plate electrode should be provided at all premises for
providing an earth system. Details of typical pipe and
plate earth electrodes are given in Fig. 3 and Fig. 4.
Although electrode material does not affect initial earth
resistance, care should be taken to select a material
which is resistant to corrosion in the type of soil in
which it is used. Under ordinary conditions of soil,
use of copper, iron or mild steel electrodes is
recommended. In case where soil condition leads to
excessive corrosion of the electrode, and the
connections, it is recommended to use either copper
electrode or copper clad electrode or zinc coastal
galvanized iron electrode. The electrode shall be kept
free from paint, enamel and grease. It is recommended
to use similar material for earth electrodes and earth
conductors or otherwise precautions should be taken
to avoid corrosion.
8.3 As far as possible, all earth connections shall be
visible for inspection and shall be carefully made; if
they are poorly made or inadequate for the purpose
for which they are intended, loss of life and property
or serious personal injury may result.
To obtain low overall resistance the current density
should be as low as possible in the medium adjacent
to the electrodes; which should be so designed as to
cause the current density to decrease rapidly with
distance from the electrode. This requirement is met
by making the dimensions in one direction large
compared with those in the other two, thus a pipe, rod
or strip has a much lower resistance than a plate of
equal surface area. The resistance is not, however,
inversely proportional to the surface area of the
electrode.
8.4 Equipment and Portions of Installations which
shall be Earthed
8.4.1 Equipment to be Earthed
Except for equipment provided with double insulation,
all the non-current carrying metal parts of electrical
installations are to be earthed properly. All metal
conduits, trunking, cable sheaths, switchgear,
distribution fuseboards, lighting fittings and all other
parts made of metal shall be bended together and
connected by means of two separate and distinct
conductors to an efficient earth electrode.
8.4.2 Structural Metal Work
Earthing of the metallic parts shall not be effected
through any structural metal work which houses the
40
NATIONAL BUILDING CODE OF INDIA
/
10 BOLTS
AND NUTS
|l fT3P— CtyP—OffiD,
CI COVER HINGED
TO CI FRAME
I— 125— H—
"zzmz.-.
65 PVC
CONDUIT
EMBEDDED-
-DETAIL
A ^WIRE
100 GL
• : ;^4^
-75-
-50— 1-25
50x3
Gl STRIP
A HOMOGENEOUS LAYER
OF COKE/CHARCOAL, SALT
AND SAND
DETAIL A
All dimensions in millimetres.
Fig. 3 Typical Arrangement of Pipe Earthing
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
41
4^
-CAST IRON OR
CI COVER
>
H
8
>
r
w
g
P
g
o
o
o
©
o
3
-E
-E
12 x 8 Gl BOLTS AND NUTS,
CHECK NUT AND WASHER
(AFTER FIXING THE OUTSIDE
SURFACE SHOULD BE COVERED
WITH BITUMIN )
1200x1200x12
Ct PLATE
-50x12 EACH
Gl STRIP
■ 12 x 60 Gl BOLTS AND NUTS CHECK NUT AND
WASHER (AFTER FIXING THE OUTER SURFACE
SHOULD BE COVERED WITH BITUMIN)
DETAIL B
DETAIL C
All dimensions in millimetres.
Fig. 4 Typical Arrangement of Plate Earthing
25 x 10 Gl PLATE
FOR CLAMP
01Ox5OmmGIBOLT ©100mm
(AFTER FIXING, THE OUTSIDE
SURFACE SHOULD BE
COVERED WITH BITUMIN)
installation. Where metallic parts of the installation are
not required to be earthed and are liable to become
alive should the insulations of conductors become
defective, such metallic parts shall be separated by
durable non-conducting material from any structural
work.
8.5 Neutral Earthing
To comply with Rule 32(1) of Indian Electricity Rules
1956, no fuses or circuit breakers other than a linked
circuit breaker shall inserted in an earthed neutral
conductor, a linked switch or linked circuit breaker
shall be arranged to break or the neutral either with or
after breaking all the related phase conductors and.
shall positively make (or close) the neutral before
making (or closing) the phases.
If this neutral point of the supply system is connected
permanently to earth, then the above rule applies
throughout the installation including 2-wire final
circuits. This means that no fuses may be inserted in
the neutral or common return wire. And the neutral
should consist of a bolted solid link, or part of a linked
switch, which completely disconnects the whole
system from the supply. This linked switch must be
arranged so that the neutral makes before, and break
after the phases.
8.6 System of Earthing
Equipment and portions of installations shall be
deemed to be earthed only if earthed in accordance
with either the direct earthing system, the multiple
earthed neutral system or the earth leakage circuit-
breaker system. In all cases, the relevant provisions of
Rules 33 and 61 of the Indian Electricity Rules, 1956
(see Annex B) shall be complied with.
The earthing of electrical installations for non-
industrial and industrial buildings shall be done in
accordance with good practice [8-2(24)].
8.7 Classification of Earthing System
The earthing systems are classified as follows:
a) TN System — A system which has one or more
points of the source of energy directly earth,
and the exposed and extraneous conductive
parts of the installation are connected by means
of protective conductors to the earth points of
the source, that is, currents to flow from the
installation to the earth points of the source.
b) TT System — A system which has one or more
points of the source of energy directly earth,
and the exposed and extraneous conductive
parts of the installation are connected to a
local earth electrodes or electrodes electrically
independent of the source earth.
c) IT System — A system which has source
either unearthed or earthed through a high
impedance and the exposed conductive
parts of the installations are connected to
electrically independent earth electrodes.
9 INSPECTION
INSTALLATION
AND TESTING OF
9.1 General Requirements
9.1.1 Before the completed installation, or an addition
to the existing installation, is put into service,
inspection and testing shall be carried out in accordance
with the Indian Electricity Rules, 1956. In the event of
defects being found, these shall be rectified, as soon
as practicable and the installation retested.
9.1.2 Periodic inspection and testing shall be carried
out in order to maintain the installation in a sound
condition after putting into service.
9.1.3 Where an addition is to be made to the fixed
wiring of an existing installation, the latter shall be
examined for compliance with the recommendations
of the Code.
9.1.4 The individual equipment and materials which
form part of the installation shall generally conform to
the relevant Indian Standard Specification wherever
applicable. If there is no relevant Indian Standard
Specification for any item, these shall be approved by
the appropriate authority.
9.1.5 Completion Drawings
On completion of the electric work, a wiring diagram
shall be prepared and submitted to the engineer-in-
charge or the owner. All wiring diagrams shall indicate
clearly, the main switch board, the runs of various
mains and submains and the position of all points and
their controls. All circuits shall be clearly indicated
and numbered in the wiring diagram and all points shall
be given the same number as the circuit in which they
are electrically connected. Also the location and
number of earth points and the run of each loads should
be clearly shown in the completion drawings.
9.2 Inspection of the Installation
9.2.1 General
On completion of wiring a general inspection shall be
carried out by competent personnel in order to verify
that the provisions of this Code and that of Indian
Electricity Rules, 1956, have been complied with. This,
among other things, shall include checking whether
all equipments, fittings, accessories, wires/cables, used
in the installation are of adequate rating and quality to
meet the requirement of the load. General workmanship
of the electrical wiring with regard to the layout and
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
43
finish shall be examined for neatness that would
facilitate easy identification of circuits of the system,
adequacy of clearances, soundness, contact pressure
and contact area. A complete check shall also be made
of all the protective devices, with respect to their
ratings, range of settings and co-ordination between
the various protective devices.
9.2.2 Item to be Inspected
9.2.2.1 Substation installations
In substation installation, it shall be checked whether:
1) The installation has been carried out in
accordance with the approved drawings;
2) Phase-to-phase and phase to earth clearances
are provided as required;
3) All equipments are efficiently earthed and
properly connected to the required number
of earth electrodes;
4) The required ground clearance to live-
terminals is provided;
5) Suitable fencing is provided with gate with
lockable arrangements;
6) The required number of caution boards fire-
fighting equipments, operating rods, rubber
mats, etc, are kept in the substation;
7) In case of indoor substation sufficient
ventilation and draining arrangements are
made;
8) All cable trenches are provided with non-
inflammable covers;
9) Free accessibility is provided for all equipments
for normal operation;
10) All name plates are fixed and the equipments
are fully painted;
11) All construction materials and temporary
connections are removed;
12) Oil-level, busbar tightness, transformer tap
position, etc, are in order;
13) Earth pipe troughs and cover slabs are
provided for earth electrodes/earth pits and
the neutral and LA earth pits are marked for
easy identification;
14) Earth electrodes are of GI pipes or CI pipes
or copper plates. For earth connections, brass
bolts and nuts with lead washers are provided
in the pipes/plates;
15) Earth pipe troughs and oil sumps/pits are free
from rubbish and dirt and stone jelly and the
earth connections are visible and easily
accessible;
16) HT and LT panels are switchgears are all
vermin and damp-proof and all unused
openings or holes are blocked properly;
17) The earth bus bars have tight connections and
corrosion-free joint surfaces;
18) Operating handle of protective device are
provided at an accessible height from ground;
19) Adequate headroom is available in the
transformer room for easy topping-up of oil,
maintenance, etc;
20) Safety devices, horizontal and vertical
barriers, bus bar covers/shrouds, automatic
safety shutters/doors interlock, handle
interlock are safe and in reliable operation in
all panels and cubicles;
21) Clearances in the front, rear and sides of the
main HV and MV and sub-switch boards are
adequate;
22) The switches operate freely; the 3 blades make
contact at the same time, the arcing horns
contact in advance; and the handles are
provided with locking arrangements;
23) Insulators are free from cracks, and are clean;
24) In transformers, there is any oil leak;
25) Connections to bushing in transformers for
tightness and good contact;
26) Bushings are free from cracks and are clean;
27) Accessories of transformers like breathers,
vent pipe, Buchholz relay, etc, are in order;
28) Connections to gas relay in transformers are
in order;
29) Oil and winding temperature are set for
specific requirements in transformers;
30) In case of cable cellars, adequate arrangements
to pump out water that has entered due to
seepage or other reasons;
31) All incoming and outgoing circuits of HV and
MV panels are clearly and indelibly labelled
for identifications;
32) No cable is damaged;
33) There is adequate clearance around the
equipments installed; and
34) Cable terminations are proper.
9.2.2.2 Medium voltage installation
,/■■
In medium voltage installations, it shall be checked
whether:
1) All blocking materials that are used for safe
transportation in switchgears, contactors,
relays, etc, are removed;
2) All connections to be earthing system are
feasible for periodical inspection;
3) Sharp cable bends are avoided and cables are
taken in a smooth manner in the trenches or
alongside the walls and ceilings using suitable
support clamps at regular intervals;
44
NATIONAL BUILDING CODE OF INDIA
4) Suitable linked switch or circuit breaker or
lockable push button is provided near the
motors/apparatus for controlling supply to the
motor/apparatus in an easily accessible
location;
5) Two separate and distinct earth connections
are provided for the motor/apparatus;
6) Control switch-fuse is provided at an accessible
height from ground for controlling supply to
overhead travelling crane, hoists, overhead
bus bar trunking;
7) The metal rails on which the crane travels are
electrically continuous and earthed and
bonding of rails and earthing at both ends are
done;
8) Four core cables are used for overhead
travelling crane and portable equipments, the
fourth core being used for earthing, and
separate supply for lighting circuit is taken;
9) If flexible metallic hose is used for wiring to
motors and other equipment, the wiring is
enclosed to the full lengths, and the hose
secured properly by approved means;
1 0) The cables are not taken through areas where
they are likely to be damaged or chemically
affected;
1 1 ) The screens and armours of the cables are
earthed properly;
12) The belts of the belt driven equipments are
properly guarded;
1 3) Adequate precautions are taken to ensure that
no live parts are so exposed as to cause danger;
14) Ammeters and voltmeters are tested;
15) The relays are inspected visually by moving
covers for deposits of dusts or other foreign
matter;
16) Wherever bus ducts/rising mains/overhead
bus trucking are used, special care should be
taken for earthing the system. All tap off
points shall be provided with adequately rated
protective device like MCB, MCCB, fuses,
ELCB, RCCB, etc;
17) All equipments shall be weather, dust and
vermin proof; and
1 8) Any and all equipments having air insulation
as media shall maintain proper distances
between phases; phase to neutral; phase to
earth and earth to neutral.
9.2.2.3 Overhead lines
For overhead lines it shall be checked whether:
1) All conductors and apparatus including live
parts thereof are inaccessible;
2) The types and size of supports are suitable
for the overhead lines/conductors used and
are in accordance with approved drawing and
standards;
3) Clearances from ground level to the lowest
conductor of overhead lines, sag conditions,
etc, are in accordance with the relevant
standard;
4) Where overhead lines cross the roads or cross
each other or are in proximity with one
another, suitable guarding is provided at road
crossings and also to protect against
possibility of the lines coming in contact with
one another;
5) Every guard wire is properly earthed;
6) The type, size and suitability of the guarding
arrangement provided is adequate;
7) Stays are provided suitably on the over-head
lines as required and are efficiently earthed
or provided with suitably stay insulators of
suitable voltages;
8) Anti-climbing devices and Danger Board/
Caution Board Notices are provided on all HT
supports;
9) Clearances along the route are checked and
all obstructions such as trees/branches and
shrubs are cleared on the route to the required
distance on either side;
1 0) Clearance between the live conductor and the
earthed metal parts are adequate;
11) For the service connections tapped-off from
the overhead lines, cut-outs of adequate
capacity are provided;
12) All insulators are properly and securely
mounted; also they are not damaged.
13) All poles are properly grouted/insulated so
as to avoid bending of pole towards tension;
and
14) Steel poles, if used shall be properly earthed.
9.2.2.4 Lighting circuits
The lighting circuits shall be checked whether;
1) Wooden boxes and panels are avoided in
factories for mounting the lighting boards and
switch controls, etc;
2) Neutral links are provided in double pole
switch-fuses which are used for lighting
control, and no protective devices (such as
MCB, MCCB, fuses, ELCB, etc) is provided
in the neutral;
3) The plug points in the lighting circuit are all
of 3-pin type, the third pin being suitably
earthed;
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
45
4) Tamper-proof interlocked switch socket and
plug are used for locations easily accessible;
5) Lighting wiring in factory area is taken
enclosed in conduit and conduit properly
earthed, or alternatively, armoured cable
wiring is used;
6) A separate earth wire is run in the lighting
installation to provide earthing for plug points,
fixtures and equipments;
7) Proper connectors and junction boxes are used
wherever joints are to be made in conductors
or cross over of conductors takes place;
8) Cartridge fuse units are fitted with cartridge
fuses only;
9) Clear and permanent identification marks
are painted in all distribution boards,
switchboards, sub-main boards and switches
as necessary;
10) The polarity having been checked and all
protective devices (such as MCB, MCCB,
fuses, ELCB, etc) and single pole switches
are connected on the phase conductor only
and wiring is correctly connected to socket-
outlets;
11) Spare knockouts provided in distribution
boards and switch fuses are blocked;
12) The ends of conduits enclosing the wiring
leads are provided with ebonite or other
suitable bushes;
13) The fittings and fixtures used for outdoor use
are all of weather-proof construction, and
similarly, fixtures, fittings and switchgears
used in the hazardous area, are of flame-proof
application;
14) Proper terminal connectors are used for
termination of wires (conductors and earth
leads) and all strands are inserted in the
terminals;
15) Flat ended screws are used for fixing
conductor to the accessories;
16) Use of flat washers backed up by spring
washers for making end connections is
desirable; and
17) All metallic parts of installation such as
conduits, distribution boards, metal boxes, etc
have been properly earthed.
9.3 Testing of Installation
9.3.1 General
After inspection, the following tests shall be carried
out, before an installation or an addition to the existing
installation is put into service. Any testing of the
electrical installation in an already existing installation
shall commence after obtaining permit to work from
the engineer-in-charge and after ensuring the safety
provisions.
9.3.2 Testing
9.3.2.1 Switchboards
HV and MV switchboards shall be tested in the manner
indicated below:
a) All high voltage switchboards shall be tested
for dielectric test as per good practice [8-
2(25)].
b) All earth connections shall be checked for
continuity.
c) The operation of the protective devices shall
be tested by means of secondary or primary
injection tests.
d) The operation of the breakers shall be tested
from all control stations.
e) Indication/signalling lamps shall be checked
for proper working.
f) The operation of the breakers shall be tested
for all interlocks.
g) The closing and opening timings of the
breakers shall be tested wherever required for
auto-transfer schemes.
h) Contact resistance of main and isolator
contacts shall be measured,
j) The specific gravity and the voltage of the
control battery shall be measured.
9.3.2.2 Transformers
Transformers are tested in the manner indicated below:
a) All commissioning tests shall be in accordance
with good practice [8-2(26)].
b) Insulation resistance on HV and MV windings
shall be measured at the end of 1 min as also
at the end of 10 min of measuring the
polarization index. The absolute value of
insulation resistance should not be the sole
criterion for determining the state of dryness
of the insulation. Polarization index values
should form the basis for determining the state
of dryness of insulation. For any class of
insulation, the polarization index should be
greater than 1.5.
9.3.2.3 Cables
Cable installations shall be checked as below:
a) It shall be ensured that the cables conform to
the relevant Indian Standards. Tests shall also
be done in accordance with good practice
[8-2(6)]. The insulation resistance before and
after the tests shall be checked.
46
NATIONAL BUILDING CODE OF INDIA
b) The insulation resistance between each
conductor and against earth shall be
measured. The insulation resistance varies
with the type of insulation used and with the
length of cable. The following empirical rule
gives reasonable guidance:
Insulation resistance in megaohms
lOx Voltage in kV
"" Length in km
c) Physical examination of cables shall be
carried out.
d) Cable terminations shall be checked.
e) Continuity test shall be performed before
charging the cable with current.
9.3.2.4 Motors and other equipments
The following test is made on motor and other
equipment:
The insulation resistance of each phase winding against
the frame and between the windings shall be measured.
Megger of 500 V or 1 000 V rating shall be used. Star
points should be disconnected. Minimum acceptable
value of the insulation resistance varies with the rated
power and the rated voltage of the motor.
The following relation may serve as a reasonable
guide:
R-
20x£ n
1000+2P
where
R. - Insulation resistance in megohms at 25°C.
E r = Rated phase to phase voltage.
P = Rated power in kW.
If the resistance is measured at a temperature different
from 25°C, the value shall be corrected to 25°C.
The insulation resistance as measured at ambient
temperature does not always give a reliable value, since
moisture might have been absorbed during shipment
and storage. When the temperature of such a motor is
raised, the insulation resistance will initially drop
considerably, even below the acceptable minimum. If
any suspicion exists on this score, motor winding must
be dried out.
9.3.2.5 Wiring installation
The following tests shall be done:
a) The insulation resistance shall be measured
by applying between earth and the whole
system of conductor or any section thereof
with all fuses in place and all switches closed,
and except in earthed concentric wiring, all
lamps in position or both poles of installation
otherwise electrically connected together, a
dc voltage of not less than twice the working
voltage, provided that it does not exceed
500 V for medium voltage circuits. Where the
supply is derived from three-wire (ac or dc)
or a poly-phase system, the neutral pole of
which is connected to earth either direct or
through added resistance the working voltage
shall be deemed to be that which is maintained
between the outer or phase conductor and the
neutral.
b) The insulation resistance in megaohms of an
installation measured as in (a) shall be not less
than 50 divided by the number of points on
the circuit, provided that the whole installation
need not be required to have an insulation
resistance greater than one megaohm.
c) Control rheostats, heating and power
appliances and electric signs, may, if desired,
be disconnected from the circuit during the
test, but in that event the insulation resistance
between the case of framework, and all live
parts of each rheostat, appliance and sign shall
be not less than that specified in the relevant
Indian Standard specification or where there
is no such specification, shall be not less than
half a megaohm.
d) The insulation resistance shall also be
measured between all conductors connected
to one pole or phase conductor of the supply
and all the conductors connected to the middle
wire or to the neutral on to the other pole of
phase conductors of the supply. Such a test
shall be made after removing all metallic
connections between the two poles of the
installation and in these circumstances the
insulation resistance between conductors of
the installation shall be not less than that
specified in (b).
9.3.2.6 Completion certificate
On completion of an electrical installation (or an
extension to an installation) a certificate shall be
furnished by the contractor, counter-signed by the
certified supervisor under whose direct supervision the
installation was carried out. This certificate shall be in
a prescribed form as required by the local electric
supply authority. One such recommended form is given
in Annex E.
9.3.2.7 Earthing
For checking the efficiency of earthing, the following
tests are done:
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
47
a) The earth resistance of each electrode shall
be measured.
b) Earth resistance of earthing grid shall be
measured.
c) All electrodes shall be connected to the grid
and the earth resistance of the entire earthing
system shall be measured.
These tests shall preferably be done during the summer
months.
10 TELECOMMUNICATION AND OTHER
MISCELLANEOUS SERVICES
10.1 Telecommunication Service
10.1.1 House wiring of telephone subscribers offices
in small buildings is normally undertaken by the
Telephone Department on the surface of walls. But
in large multi-storeyed buildings intended for
commercial, business and office use as well as for
residential purposes, wiring for telephone connections
is generally done in a concealed manner through
conduits.
10.1.2 The requirements of telecommunication
facilities like Telephone connections, Private Branch
Exchange, Intercommunication facilities, Telex and
Telegraph lines are to be planned well in advance so
that suitable provisions are made in the building plan
in such a way that the demand for telecommunication
services in any part of the building at any floor are
met at any time during the life of the building.
10.1.3 Layout arrangements, methods for internal
block wiring and other requirements regarding
provisions of space, etc, may be decided defending as
the number of phone outlets and other details in
consultation with Engineer/ Architect and user.
10.2 Public Address System
Life Safety'.
- See Part 4 Tire and
10.3 Common Antenna System for TV Receivers
10.3.1 In multistoreyed apartments, houses and hotels
where many TV receivers are located, a common
master antenna system may preferably be used to avoid
mushrooming of individual antennas.
10.3.2 Master antenna is generally provided at the top
most convenient point in any building and a suitable
room on the top most floor or terrace for housing the
amplifier unit, etc, may also be provided in consultation
with the architect/engineer.
10.3.3 From the amplifier rooms, conduits are laid in
recess to facilitate drawing co-axial cable to individual
flats. Suitable 'Tap Off boxes may be provided in
every room/flat as required.
10.4 UPS System
An electrical device providing an interface between
the mains power supply and sensitive loads (computer
systems, instrumentation, etc). The UPS supplies
sinusoidal a.c. power free of disturbances and within
strict amplitude and frequency tolerances. It is
generally made up of a rectifier/charger and an inverter
together with a battery for backup power in the event
of a mains failure with virtually no time lag.
In general UPS system shall be provided for sensitive
electronic equipments like computers, printers, fire
alarm panel, public address system equipment, access
control panel, EPABX, etc with the following
provisions:
a) Provisions of isolation transformers shall be
provided where the capacity exceeds 5 kVA.
b) UPS shall have dedicated neutral earthing
system.
c) Adequate rating of protective devices such as
MCB, MCCB, fuses, ELCB, etc, shall be
provided at both incoming and outgoing sides.
d) UPS room shall be provided with adequate
ventilation and/or air conditioning as per
requirement.
10.5 Inverter
In general inverter system shall be provided for house
lighting, shop lighting, etc, with the following
provisions:
a) Adequate rating of protective devices such as
MCB, MCCB, fuses, ELCB, etc, shall be
provided at both incoming and outgoing sides.
b) Earthing shall be done properly.
c) Adequate ventilation space shall be provided
around the battery section of the inverter.
d) Care in circuit design to keep the connected
load in such a manner that the demand at the
time of mains failure is within the capability
of the inverter. (If the inverter fails to take
over the load at the time of the mains failure,
the purpose of providing the inverter and
battery back up is defeated.)
e) Circuits which are fed by the UPS or Inverter
systems should have suitable marking to
ensure that a workman does not assume that
the power is off, once he has switched off the
mains from the DB for maintenance.
f) UPS systems and Inverter systems have a very
limited fault feeding capacity in comparison
to the mains supply from the licensee's
network. The low fault current feed may cause
loss of discrimination in the operation of
48
NATIONAL BUILDING CODE OF INDIA
MCB ' s, if the Inverter or UPS system feeds a
number of circuits with more than one over
current protective device in series (such as
incoming MCB at the DB and a few outgoing
MCB's). The choice of MCB's in such cases
has to be done keeping the circuit operating and
fault condition parameters under both (mains
operation and UPS operation) conditions.
10.6 Diesel Generating Set (less than 5 kVA)
In general small diesel generating sets shall be provided
for small installations such as offices, shops, small scale
industry, hostels, etc, with the following provisions:
a) These shall be located near the exit or outside
in open areas.
b) They shall be in reach of authorized persons
only.
c) Adequate fire fighting equipment shall be
provided near such installations.
d) Exhaust from these shall be disposed in such
a way so as not to cause health hazard.
e) These shall have acoustic enclosure, or shall
be placed at a location so as not to cause noise
pollution.
f) Adequate ventilation shall be provided around
the installation.
g) Adequate rating of protective devices such as
MCB, MCCB, fuses, ELCB, etc, shall be
provided.
h) Separate and adequate body and neutral
earthings shall be done.
10.7 Building Management System
A building management/automation system may be
considered to be provided for controlling and
monitoring of all parameters of HVAC, electrical,
plumbing, fire fighting, low voltage system such as
telephone, TV, etc. This not only lead to reduction of
energy consumption, it shall also generate data leading
to better operation practice and systematic maintenance
scheduling. The total overview provided by a Building
Automation System, with a capability to oversee a large
number of operating and environmental parameters on
real time basis leads to introduction of measures which
lead to further reduction in energy consumption.
It shall also help in reduction of skilled manpower
required for operation and maintenance of large
complexes. This system can further linked to other
systems such as Fire alarm system, public address
system, etc for more effective running of services.
This system can be used for analysis and controlling
of all services in a particular complex, leading efficient
and optimum utilization of available services.
10.8 Security System
Security System may be defined as an integrated
Closed Circuit Television System, Access Control
System, Perimeter Protection Systems, movement
sensors, etc. These have a central control panel, which
has a defined history storage capacity. This main
control panel may be located near to the fire detection
and alarm system.
These may be considered for high security areas or
large crowded areas or complexes. High security areas
may consider uncorded, high-resolution, black and
white cameras inplace of coloured cameras. These may
be accompanied with movement sensors.
Access control may be provided for entry to high
security areas. The systems may have proximity card
readers, magnetic readers, etc.
10.9 Computer Networking
Networking is the practice of linking computing
devices together with hardware and software
that supports data communications across these
devices.
10.10 Car Park Management System
The Car Management System may be provided in
multi-level parking or other parking lots where number
of vehicles to be parked exceeds 1 000 vehicles. The
Car Park Management System may have features of
Pay and Display Machines and Parking Guidance
System. The Pay and Display Machines may be
manned and unmanned type. Parking guidance system
needs to display number of car spaces vacant on various
floors, direction of entry and exit, etc. This system can
be of great benefit in evaluating statistical data's such
as number of cars in a day or month or hour, stay time
of various vehicles, etc.
11 LIGHTNING PROTECTION OF BUILDINGS
11.1 Basic Considerations for Protection
Before proceeding with the detailed design of a
lightning protecting system, the following essential
steps should be taken:
a) Decide whether or not the structure needs
protection and, if so, what are the special
requirements {see 11.1.1) {see good practice
for details [8-2(27)] }.
b) Ensure a close liaison between the architect,
the builder, the lightning protective system
engineer, and the appropriate authorities
throughout the design stages.
c) Agree the procedures for testing, commissioning
and future maintenance.
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
49
11.1.1 Need for Protection
Structures with inherent explosive risks; for example,
explosives factories, stores and dumps and fuel tanks;
usually need the highest possible class of lightning
protective system.
For all other structures, the standard of protection
recommended in tfte remainder of the Code is
applicable and the only question remaining is whether
to protect or not.
In many cases, the need for protection may be self-
evident, for example:
— where large numbers of people congregate;
— where essential public services are concerned;
— where the area is one in which lightning
strokes are prevalent;
— where there are very tall or isolated structures;
and
— where there are structures of historic or
cultural importance.
However, there are many cases for which a decision is
not so easy to make. Various factors effecting the risk
of being struck and the consequential effects of a stroke
in these cases are discussed in 11.1.2 to 11.1.8.
It must be understood, however, that some factors
cannot be assessed, and these may override all other
considerations. For example, a desire that there should
be no avoidable risk to life or that the occupants of a
building should always feel safe, may decide the
question in favour of protection, even though it would
normally be accepted that there was no need. No
guidance can be given in such matters, but an
assessment can be made taking account of the exposure
risk (that is the risk of the structure being struck) and
the following factors:
a) Use to which the structure is put,
b) Nature of its construction,
c) Value of its contents or consequential effects,
d) The location of the structure, and
e) The height of the structure (in the case of
composite structures the overall height).
11.1.2 Estimation of Exposure Risk
The probability of a structure or building being struck
by lightning in any one year is the product of the
lightning flash density' and the 'effective collection
area' of the structure. The lightning flash density,
N , is the number of (flashes to ground) per km 2 per
year.
NOTE — For the purposes of this Code, the information given
in Fig. 5 on thunderstorm days per year would be necessary to
be translated in terms of estimated average annual density N .
The table below which indicates the relationship between
thunderstorm days per year and lightning flashes per square
kilometre per year:
Thunderstorm
Lightning Flashes per
km 2 per Year
days/year
>^
Mean
Limits
5
0.2
0.1-0.5
10
0.5
0.15-1
20
1.1
03-3
30
1.9
0.6-5
40
2.8
0.8-8
50
3.7
1.2-10
60
4.7
1.8-12
80
6.9
3-17
100
9.2
4-20
The effective collection area of a structure is the area
on the plan of the structure extended in all directions
to take account of its height. The edge of the effective
collection area is displaced from the edge of the
structure by an amount equal to the height of the
structure at that point. Hence, for a simple rectangular
building of length L, width W and height H metres, the
collection area has length (L + 2H) metres and width
(W + 2H) metres with four rounded corners formed by
quarter circles of radius H metres. This gives a
collection area, A (in m 2 ):
A^iLxWt+liLxfD + liWxfD+TTH 2
(1)
The probable number of strikes (risk) to the structure
per year is:
P = A x W x 10-*
(2)
It must first be decided whether this risk P is acceptable
or whether some measure of protection is thought
necessary.
11.1.3 Suggested Acceptable Risk
For the purposes of this Code, the acceptable risk
figure has been taken as 10" 5 , that is, 1 in 100 000 per
year.
11.1.4 Overall Assessment of Risk
Having established the value of P, the probable number
of strikes to the structure per year [see equation (2)
in 11.1.2] the next step is to apply the 'weighting
factors' in Tables 3 and 4.
This is done by multiplying P by the appropriate factors
to see whether the result, the overall weighting factors,
exceeds the acceptable risk of P = 10' 5 per year.
11.1.5 Weighting Factors
In Tables 3A to 3E, the weighting factor values are
given under headings 'A' to 'E', denoting a relative
degree of importance or risk in each case. The tables
are mostly self-explanatory but it may be helpful to
say something about the intention of Table 3C.
50
NATIONAL BUILDING CODE OF INDIA
Table 3 Overall Assessment of Risk
(Clauses 1 1.1. 4 and 11.1.5)
Table 3A Weighting Factor 'A'
(Use of Structure)
Use to Which Structure is Put Value of 'A'
Houses and other buildings of comparable size 0.3
Houses and other buildings of comparable size 0.7
with outside aerial
Factories, workshops and laboratories 1.0
Office blocks, hotels, blocks of flats and other 1.2
residential buildings other than those included
below
Places of assembly, for example, churches, 1.3
halls, theatres, museums, exhibitions,
departmental stores, post offices, stations,
airports, and stadium structures
Schools, hospitals, children's and other homes 1 .7
Table 3B Weighting Factor 'B'
(Type of Construction)
Type of Construction
Value of *B>
Steel framed encased with any roof other than
metal
0.2
Reinforced concrete with any roof other than
metal
0.4
Steel framed encased or reinforced concrete
with metal roof
0.8
Brick, plain concrete or masonry with any roof
other than metal or thatch
1.0
Timber framed or clad with any roof ohte rthan
metal or thatch
1.4
Brick, plain concrete, masonry, timber framed
but with metal roofing
.1.7
Any building with a thatched roof
2.0
A structure of exposed metal which is continuous down to
ground level is excluded from these tables as it requires no
lighting protection beyond adequate earthing arrangements.
Table 3C Weighting Factor <C 9 (Contents or
Consequential Effects)
Contents or Consequential Effects
Ordinary domestic or office buildings,
factories and workshops not containing
valuable or specially susceptible contents
Industrial and agricultural buildings with
specially susceptible } contents
Power stations, gas works, telepone exchanges,
radio stations
Industrial key plants, ancient monuments and
historic buildings, museums, art galleries or
other buildings with specially valuable
contents
Schools, hospitals, children's and other homes,
places of assembly
Value of *C
0.3
0.8
1.0
1.3
1.7
Table 3D Weighting Factor 'D'
(Degree of Isolation)
Degree of Isolation Value of 'D'
Structure located in a large area of structures or 0.4
trees of the same or greater height, for example,
in a large town or forest
Structure located in an area with few other 1.0
structures or trees of similar height
Structure completely isolated or exceeding at 2.0
least twice the height of surrounding structures
or trees
Table 3E Weighting Factor <E'
(Type of Country)
Type of Country
Flat country at any level
Hill country
Mountain country between 300 m and 900 m
Mountain country between 900 m
Value of <E'
0.3
1.0
1.3
1.7
} This means specially valuable plant or materials vulnerable to
fire or the results of fire.
The effect of the value of the contents of a structure is
clears the term 'consequential effect' is intended to
cover not only material risks to goods and property
but also such aspects as the disruption of essential
services of all kinds, particularly in hospitals.
The risk to life is generally very small, but if a building
is struck, fire or panic can naturally result. All possible
steps should, therefore, be taken to reduce these effects,
especially among children, the old, and the sick.
11.1.6 Interpretation of Overall Risk Factor
The risk factor method put forward here is to be taken
as giving guidance on what might, in some cases, be a
difficult problem. If the result obtained is considerably
less than 10 -5 (1 in 100 000) then, in the absence of
other overriding considerations, protection does not
appear necessary; if the result is greater than 10" 5 , say
for example 10 -4 (1 in 10 000) then sound reasons
would be needed to support a decision not to give
protection.
When it is thought that the consequential effects will
be small and that the effect of a lighting stroke will
most probably be merely slight damage to the fabric
of the structure, it may be economic not to incur the
cost of protection but to accept the risk. Even though,
this decision is made, it is suggested that the calculation
is still worthwhile as giving some idea of the magnitude
of the calculated risk being taken.
11.1.7 Anomalies
Structures are so varied that any method of assessment
may lead to anomalies and those who have to decide on
protection must exercise judgement. For example, a
steel-framed building may be found to have a low risk
PARTS BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
51
factor but, as the addition of an air termination and
earthing system will give greatly improved protection,
the cost of providing this may be considered worthwhile.
A low risk factor may result for chimneys made of
brick or concrete. However, where chimneys are free
standing or where they project for more than 4.5 m
above the adjoining structure, they will require
protection regardless of the factor. Such chimneys are,
therefore, not covered by the method of assessment.
Similarly, structures containing explosives or
flammable substances are also not covered.
Results of calculations for different structures are given
in Table 4 and a specific case is worked through
in 11.1.8.
11.1.8 Sample Calculation of Need for Protection
A hospital building is 10 m high and covers an area of
70 m x 12 m. The hospital is located in flat country
and isolated from other structures. The construction is
of brick and concrete with a non-metallic roof.
Is lighting protection needed?
a) Flashes/km 2 /year — Let us say, for the
protection of the hospital a value for N is 0.7.
b) Collection area — Using equation (1)
in 11.1.2.
A c = (70 x 12) + 2 (70 x 10) + 2 (12 x 10)
+ (n x 100)
= 840+1400 + 240 + 314
= 2 794 m 2
c) Probability of being struck — Using equation
(2) in 11.1.2:
P ~ A x N x 10" 6 times per year
= 2 794 x 0.7 x 10^
= 2.0 x 10 3 approximately
Table 4 Examples of Calculations for Evaluating the Need for Protection
(Clauses 1 1. 1 A and 11.1.7)
SI Description Risk of Being Struck (P)
No. of Structure a
Weighting Factors
Overall Overall Recommen-
Muiti- Risk dation
plying Factor
Factor (Product
(!)
(2)
Collection Flash P 'A' *B* 'C 'D* 'E'
Area Density Ac x N$ Use of Type of Contents or Degree Type of (Product of cols 5
Ac N g x 10" 6 Structure Const- Consequen- of Country of and 11)
(Table ruction tial Effects Isolation (Table cols 6-10)
3A) (Table {Table 3 C) < Table 3E )
3B) 3D)
(3) (4) (5) (6) (7) (8) (9) (10) (11) (12)
(13)
i) Maisonette,
3 327
0.6
2 x 10~ 3
1.2
0.4
0.3
0.4
0.3
0.02
4 x 10 Protection
reinforced
required
concrete and
brick built,
non-metallic
roof
ii) Office
4 296
0.6
2.6 x 10 3
1.2
0.4
03
0.4
0.3
0.02
5.2 x \0 5 Protection
building,
required
reinforced
concrete
construction,
non-metallic
roof
iii) School, brick
1456
0.7
1 x 10" 3
1.7
1.0
1.7
0.4
0.3
0.3
3 x Kf 4 Protection
built
required
iv) 3 bedroom
405
0.4
1.6 x 10^
0.3
1.0
0.3
0.4
0.3
0.01
1.6 x lO^No
detached
protection
dwelling
required
house, brick
built
v) Village
5 027
0.6
3 x 10" 3
1.3
1.0
1.7
2.0
0.3
1.3
3.9 x 10" 3 Protection
church
required
NOTE — The risk of being struck, */>* (col 5), is multiplied by the product of the weighting factors (col 6 to 1 0) to yield an overall risk
factor (col 12). This should be compared with the acceptable risk (1 x 10" ) for guidance on whether or not to protect.
52
NATIONAL BUILDING CODE OF INDIA
d) Applying the weighting factors
A = 1.7
B = 1
C = 1.7
D = 2.0
E = 0.3
The overall multiplying factor
=AxBxCxDxE
= 1.7
Therefore, the overall risk factor
= 2.0x 1.7 x 10 3
= 3.4 x 10- 3
Conclusion: Protection is necessary.
11.2 For detailed requirements of lightning protection
of various structures, reference may be made to good
practice [8-2(27)].
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
53
SI
Name of
Annual
SI
Name of
Annual
SI
Name of
Annual
No.
Place
Thunder-
storm Days
No.
Place
Thunder-
storm Days
No.
Place
Thunder-
storm Days
1.
Gilgit
1
63.
Dumka
63
125.
Nagpur
45
2.
Skardu
5
64.
Darjeeling
28
126.
Gondia
10
3.
Gulmarg
53
65.
Jalpaiguri
68
127.
Aurangabad
34
4.
Srinagar
54
66.
Malda
59
128.
Bombay
16
5.
Dras
3
67.
Asansol
71
129,
Alibag
12
6.
Kargil
2
68.
Buidwan
39
130.
Ahmadnagar
10
7.
Leh
3
69.
Kharagpur
76
131.
Parbhani
32
8.
Jammu
26
70.
Calcutta
70
132.
Pune
22
9.
Dharmsala
13
71.
Sagar Island
41
133.
Mahabaleshwar
14
10.
Amritsar
49
72.
Dhubri
8
134.
Ratnagiri
6
11.
Pathankot
4
73.
Tezpur
27
135.
Sholapur
23
12.
Mandi
46
74.
Dibrugarh
98
136.
Miraj
25
13.
Ludhiana
12
75.
Sibsagar
103
137.
Vengurla
39
14.
Simla
40
76.
Shillong
75 .
138.
Nizambad
36
15.
Patiala
26
77.
Cherrapunji
49
139.
Hnamkonda
43
16.
Ambala
9
78.
Silchar
33
140.
Hyderabad
28
17.
Hissar
27
79.
Kohima
34
141.
Khammam
26
18.
Delhi
30
80.
Imphal
49
142.
Kalingapatam
20
19.
Bikaner
10
81.
Deesa
7
143.
Vishakapatnam
46
20.
Phalodi
14
82.
Dwarka
5
144.
Rentichintala
42
21.
Sikar
17
83.
Jamnagar
8
145.
Masulipatam
20
22.
Banner
12
84.
Rajkot
12
146.
Ongole
25
23.
Jodhpur
23
85.
Ahmedabad
11
147.
Kurnool
29
24.
Ajmer
26
86.
Dohad
17
148.
Anantpur
22
25.
Jaipur
39
87.
Porbandar
3
149.
Nellore
18
26.
Kankroli
36
88.
Veraval
3
150.
Bidar
15
27.
Mount Abu
5
89.
Bhavnagar
11
151.
Gulbarga
34
28.
Udaipur
38
90.
Baroda
8
152.
Bijapur
9
29.
Neemuch
28
91.
Surat
4
153.
Belgaum
31
30.
Kota
27
92.
Gwalior
53
154.
Raichur
17
31.
Jhalawar
40
93.
Guna
33
155.
Gadag
21
32.
Mussorie
61
94.
Nowgong
59
156.
Bellary
22
33.
Roorkee
74
95.
Satna
41
157.
Karwar
27
34.
Najibabad
36
96.
Sagar
36
158.
Honavar
5
35.
Mukteswar
53
97.
Bhopal
44
159.
Chikalthana
24
36.
Meerut
—
98.
Jabalpur
50
160.
Mangalore
36
37.
Bareilly
34
99.
Umaria
37
161.
Hassan
26
38.
Aligarh
30
100.
Ambikapur
29
162.
Bangalore
46
39.
Agra
24
101.
Indore
34
163.
Mysore
44
40.
Mainpuri
23
102.
Hoshangabad
37
164.
Kozhikode
39
41.
Bahraich
31
103.
Panchmarhi
30
165.
Palghat
35
42.
Gonda
22
104.
Seoni
51
166.
Cochin
69
43.
Lucknow
18
105.
Pendadah
56
167.
Alleppey
51
44.
Kanpur
26
106.
Raipur
34
168.
Trivandrum
68
45.
Fatehpur
24
107.
Chhindwara
27
169.
Vellore
25
46.
Jhansi
20
108.
Ranker
37
170.
Madras
47
47.
Allahabad
51
109.
Jagdalpur
35
171.
Ootacamund
24
48.
Varanasi
51
110.
Balasore
81
172.
Salem
69
49.
Azamgarh
1
111.
Chandbali
75
173.
Cuddalore
37
50.
Gorakhpur
11
112.
Angul
81
174.
Coimbatore
40
51.
Kathmandu
74
113.
Bhubaneswar
46
175.
Trichchirapalli
41
52.
Motihari
38
114.
Puri
33
176.
Nagappattinam
15
53.
Darbhanga
10
115.
Gopalpur
34
177.
Kodaikanal
82
54.
Patna
33
116.
Jharsuguda
85
178.
Madurai
39
55.
Gaya
38
117.
Sambalpur
67
179.
Pamban
5
56.
Daltonganj
73
118.
Tidagarh
24
180.
Tuticorin
14
57.
Hazaribagh
73
119.
Rajgangpur
1
181.
Cape Comorin
68
58.
Ranchi
34
120.
Dahanu
1
182.
Port Blair
62
59.
Chaibasa
70
121.
Nasik
17
183.
Car Nicobar 1
18
60.
Jamshedpur
66
122.
Malegaon
13
184.
Minicoy 1
20
61.
Purnea
52
123.
Akola
20
62.
Sabour
76
124.
Amraoti
32
54
NATIONAL BUILDING CODE OF INDIA
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INDIA
PLACES FOR AVERAGE NUMBER OF
THUNDERSTORM DAYS
IN A YEAR
,.,y
19
21
24 #25
23# •
\ •" #26 •»-.
*» #32 35 v
36 #33 •'
>
v..
. MA *1frt a iaa -~a *7rt^l wns. \ 1
Y
">*
-4
Based upon Survey of India Outline Map printed in 1993.
© Government of India Copyright, 2005
The territorial waters of India extend into the sea to a distance of twelve nautical miles measured from the appropriate base line.
The boundary of Meghalaya shown on this map is as interpreted from the North-Eastern Areas (Reorganisation) Act, 1971, but has yet to be verified
Responsibility for correctness of internal details shown on the map rests with the publisher.
The state boundaries between Uttaranchal & Uttar Pradesh, Bihar & Jharkhand and Chhatisgarh & Madhya Pradesh have not been verified by Governments concerned.
Fig. 5 Map of India Showing Places for Average Number of Thunderstorm Days in a Year
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
55
ANNEX A
(Clause 2.2)
DRAWING SYMBOLS FOR ELECTRICAL INSTALLATION IN BUILDING
A-l WIRING
A-2.2.3 Distribution Fuse Board
A-1.0 Remarks 'upwards' and 'downwards' apply Without Switches
W/////////M
only when the drawing is read the right way up.
A-l.0.1 An arrow on the slant line indicates the Switches
direction of the power flow.
A-l.0.2 The wiring terminates at the circle or the black
dot.
A-l.l General Wiring
A- 1.2 Wiring on the Surface
m m
A-1.3 Wiring under the Surface
ay iu
A-.1.4 Wiring in Conduit
o
A-l.4.1 Conduit on Surface
m m
A-l.4.2 Concealed Conduit
UJQ w
NOTE — The type of conduit may be indicated, if necessary.
A-1.5 Wiring Going Upwards
</
A-1.6 Wiring Going Downwards
/
A-1.7 Wiring Passing Vertically
XX
through a Room
A-2 FUSE BOARDS
A-2.1 Lighting Circuit Fuse Boards
A-2.1.1 Main Fuse Board Without
Switches
A-2. 1.2 Main Fuse Board with
Switching
A-2.1.3 Distribution Fuse Board
Without Switches
A-2.1.4 Distribution Fuse Board with
Switches
A-2.2 Power Circuit Fuse Boards
A-2.2.1 Main Fuse Board Without
Switches
A-2.2.2 Main Fuse Board with Switches
56
'/////A
A-2.2.4 Distribution Fuse Board with \\ "-'—"-\ \
A-3 SWITCHES AND SWITCH-OUTLETS
A-3.1 One-Way Switch
A-3.1.1 Single-Pole
■s
A-3.1.2 Two-Pole
s
A-3.1.3 Three-Pole
s
A-3.2 Single-Pole Pull Switch
s
A-3.3 M ultiposition Switch for
Different Degrees of Lighting
V
A-3.4 Two- Way Switch
/
A-3.5 Intermediate Switch
X
A-3.6 Period Limiting Switch
of
A-3.7 Time Switch
IG-"-l
A-3.8 Pendant Switch
A-3.9 Push Button
/ p
NOTE — The use of th6 push button may be indicated, if
desired.
A-3.10 Luminous Push Button
A-3.11 Restricted Access Push Button | O |
A-4 SOCKET-OUTLETS
A-4.1 Socket-Outlet, 6A
A-4.2 Socket-Outlet, 16A
A-4.3 Combined Switch and Socket-
Outlet, 6 A
A
NATIONAL BUILDING CODE OF INDIA
A-4.4 Combined Switch and Socket- ^^
Outlet, 16 A
A-4.5 Interlocking Switch and Socket- f\
Outlet, 6 A
A-4.6 Interlocking Switch and Socket- L^
Outlet, 16 A
A-5 LAMPS AND LIGHTING APPARATUS
A-5.0 Symbols A-5.1 to A-5.17.1 represent either the
lamp or a group of lamps or the outlet for lamps. If it
is desired to specify that the lamp is fixed to the wall
or coiling, a vertical or horizontal line respectively may
be added to the symbol.
A-5.1 Lamp or Outlet for Lamp y\
A-5.1.1 Group of Three 40-W Lamps X 3 x 40 w
A-5.2 Lamp, Mounted on a Wall Pn
A-5.3 Lamp, Mounted on a Ceiling y\
A-5.4 Counter Weight Lamp Fixture s£»
A-5.5 Chain Lamp Fixture
A-5.6 Rod Lamp Fixture
n
A-5.7 Lamp Fixtures with Built-in ^^
Switch
A-5.8 Lamp Fed from Variable Voltage ^^
Supply
X
v5-
A-5.9 Emergency Lamp
A-5.10 Panic Lamp
A-5.11 Bulk-Head Lamp
A-5.12 Water-Tight Lighting Fitting ^ WT
A-5.13 Battern Lamp Holder ^< BH
A-5.14 Projector
A-5.15 Spot Light
A-5.16 Flood Light
A-5.17 Flourescent Lamp
i — i
A-5.17.1 Group of Three 40-W ^
Fluorescent Lamps
3x40W
A-6 ELECTRICAL APPLIANCES
A-6.1 General
NOTE — If necessary, use designation is specify.
A-6.2 Heater 1 | | |
ft
A-6.3 Storage Type Electric Water
Heaters
A-7 BELLS, BUZZERS AND SIRENS
A-7.1 Bell
A-7.2 Buzzer
A-7.3 Siren
A-7.4 Horn on Hooter
A-7.5 Indicator (at *N* insert
number of ways)
A-8 FANS
A-8.1 Ceiling Fan
A-8.2 Bracket Fan
A-8.3 Exhaust Fan
A-8.4 Fan Regulator ^
A-9 TELECOMMUNICATION APPARATUS
rwi
oo
B
C*
A-9.1 Socket-Outlet for
Telecommunications
A-9.2 Aerial
A-9.3 Loudspeaker
x
Y
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
57
A-9.4 Radio Receiving Set
A -9.5 Amplifying Equipment
A-9.6 Television Receiving Set
A-9.7 Control Board
(for Public Address System)
A-10 CLOCKS
A-10.1 Synchronous Clock
A-10.2 Impulse Clock Outlet
A-10.3 Master Clock Outlet
o
o o o o o
All FIRE ALARMS
A-ll.l Manual Operated Fire Alarm
A-11.2 Automatic Fire Detector Switch
A-11.3 Bell Connected to Fire Alarm
Switch
it
A-11.4 Fire Alarm Indicator
A-12 EARTHING
A-12.1 Earth Point
CO
ANNEX B
[Clauses 3.1, 5.3.1.1, 5.3.1.3, 5.3.2.3(b) and 8.6]
EXTRACTS FROM INDIAN ELECTRICITY RULES, 1956
B-l The following are the extracts of some of the
rules:
Rule 32, Identification of Earthed and Earthed
Neutral Conductors and Position of Switches and
Cut-Outs Therein
Where the conductors include an earthed conductor of
a two-wire system or an earthed neutral conductor of
a multi-wire system or a conductor which is to be
connected thereto, the following conditions shall be
complied with:
1) An indication of permanent nature shall be
provided by the owner of the earthed or
earthed neutral conductor, or the conductor
which is to be connected thereto, to enable
such conductor to be distinguished from any
live conductor. Such indication shall be
provided:
a) Where the earthed or earthed neutral
conductor is the property of the supplier,
at or near the point of commencement of
supply;
b) Where a conductor forming part of a
consumer' s system is to be connected to
the supplier's earthed or earthed neutral
conductor at the point where such
connection is to be made;
c) In all other cases, at a point corresponding
to the point of commencement of supply
or at such other point as may be approved
by an Inspector or any officer appointed
to assist the Inspector and hold authorized
under sub-rule (2) of Rule 4-A.
2) No cut-out, link or switch other than a linked
switch arranged to operate simultaneously on
the earthed or earthed neutral conductor and
live conductors shall be inserted or remain
inserted in any earthed or earthed neutral
conductor of a two-wire system or in any
earthed or earthed neutral conductor of a
multi-wire system or in any conductor
connected thereto with the following
exceptions:
a) A link for testing purposes, or
b) A switch for use in controlling a generator
or transformer.
NOTE — For the purpose of this rule, the relevant
Indian Standards relating to marking and arrangement
for switch gear, busbar, main connections, and auxiliary
wiring may be referred to.
Rule 33 Earthed Terminal on Consumer's Premises
1) The supplier shall provide and maintain on
the consumer's premises for the consumer's
use a suitable earthed terminal in an accessible
58
NATIONAL BUILDING CODE OF INDIA
position at or near the point of commencement
of supply as defined under Rule 58;
Provided that in the case of medium, high or
extra-high voltage installation, the consumer
shall, in addition to aforementioned earthing
arrangement, provide his own earthing system
with an independent electrode, and maintain
the same.
Provided further that the supplier may not
provide any earthed terminal in the case of
installations already connected to his system
on or before the 30th June, 1966 if he is
satisfied that the consumer's earthing
arrangement is efficient.
2) The consumer shall take all reasonable
precautions to prevent mechanical damage to
the earthed terminal and its lead belonging to
the supplier; and
3) The supplier may recover from the consumer
the cost of installation of such earthed
terminal on the basis laid down in sub-rule (2)
of Rule 82.
Rule 50 Supply and Use of Energy
1 ) The energy shall not be supplied, transformed,
converted or used or continued to be supplied,
transformed, converted or used unless the
following provisions are observed:
a) A suitable linked switch or a circuit
breaker of requisite capacity to carry and
break the current is placed as near
as possible to, but after the point of
commencement of supply, as defined
under Rule 58, so as to be readily
accessible and capable of being easily
operated to completely isolate the supply
to the installation, such equipment being
in addition to any equipment installed
for controlling individual circuits or
apparatus.
Provided that where the point of
commencement of supply and the
consumer's apparatus are near to each
other, one linked switch or circuit breaker
near the point of commencement of
supply shall considered sufficient for the
purpose of this rule;
b) A suitable linked switch or circuit-
breaker of requisite capacity to carry and
break the full load current is inserted on
the secondary side of a transformer, in
the case of high or extra high voltage
installation.
Provided however, that the linked switch
on the primary side of the transformer
may be of such capacity as to carry the
full load current and to break only the
magnetising current of the transformer.
Provided further that the provision of the
clause shall not apply to transformers
installed in sub-station upto and
including 100 kVA belonging to the
supplier.
Provided also that the provision of a
linked switch on the primary side of the
transformer shall not apply to the unit
auxiliary transformer of the generator.
c) Except in the case of composite control
gear designed as a unit; every distinct
circuit is protected against excess energy
by means of a suitable cut-out or a circuit-
breaker of adequate breaking capacity
suitably located and so constructed as to
prevent danger from overheating, arcing
or scattering of hot metal when it comes
into operation and to permit of ready
renewal of the fusible metal of the cut-
out without danger.
d) The supply of energy to each motor or a
group of motors or other apparatus,
meant for operating one particular
machine, is controlled by a suitable
linked switch or a circuit-breaker or an
emergency tripping device with manual
reset of requisite capacity placed in such
a position as to be adjacent to the motor
or a group of motors or other apparatus,
readily accessible to and easily operated
by the person in charge and so connected
in the circuit of that by its means all
supply of energy can be cut-off from the
motor or a group of motors or apparatus
and from any regulating switch,
resistance or other device associated
therewith.
e) All insulating material is chosen with
special regard to the circumstances of its
proposed use, the mechanical strength
being sufficient for the purpose, and so
far as is practicable, is of such a character
or so protected as to maintain adequately
the insulating properties under all
working conditions in respect of
temperature and moisture; and
f) Adequate precautions are taken to ensure
that no live parts are so exposed as to
cause danger.
2) a) When energy is being supplied,
transformed, converted or used, the
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
59
consumer or the owner of the concerned
installation shall be responsible for the
continuous observance of the provisions
of sub-rule(l) in respect of his
installation.
b) Every consumer shall use all reasonable
means to ensure that where energy is
supplied by a supplier no person other
than the supplier shall interfere with the
service lines and apparatus placed by the
supplier on the premises of the consumer.
Rule 51 Provisions Applicable to Medium, High or
Extra-High Voltage Installations
The following provisions shall be observed where
energy at medium, high or extra high voltage is
supplied, converted, transformed or used:
1) a) All conductors (other than those of
overhead lines) shall be completely
enclosed in mechanically strong metal
casing or metallic covering which is
electrically and mechanical continuous
and adequately protected against
mechanical damage unless the said
conductors are accessible only to an
authorised person or are installed and
protected to the satisfaction of the
Inspector so as to prevent danger.
Provided that rigid non-metallic conduits
conforming to IS 2509 : 1963 'Rigid
non-metallic conduits for electrical
installation', may be used for medium
voltage installation subject to any
conditions as the Inspector or officer
appointed to assist an Inspector may
think fit to impose.
b) All metal works enclosing, supporting or
associated with the installation, other than
that designed to serve as a conductor
shall, if considered necessary by the
Inspector, be connected with earth.
c) Every switchboard shall comply with the
following provisions, namely:
i) a clear space of not less than one
metre in width shall be provided in
front of the switchboard;
ii) if there are any attachments or bare
connections at the back of the
switchboard, the space (if any)
behind the switchboard shall be
either less than 10 cm, or more than
75 cm in width, measured from the
farthest outstanding part of any
attachment or conductor; and
iii) if the space behind the switchboard
exceeds 75 cm in width, there shall
be passage way from either end of
the switchboard clear to a height of
1.8 metres.
2) Where an application has been made to
a supplier for supply of energy to any
installation, the shall not commence, or
where the supply has been discontinued,
recommence the supply unless he is satisfied
that the consumer has complied in all respects
with the conditions of supply, set out in sub-
rule (1) of this rule and Rules 50 and 64.
3) Where a supplier proposes to supply or use
energy at medium voltage or to recommence
supply after it has been discontinued for
a period of six months, he shall, before
connecting or re-connecting the supply, give
notice in writing of such intention to the
Inspector.
4) If at any time after connecting the supply the
supplier is satisfiedthat any provision of sub-
rule (1) of this rule, or of Rules 50 and 64 is
not being observed, he shall give notice of
the same in writing to the consumer and the
Inspector specifying how the provision has
not been observed, and may discontinue the
supply if the Inspector so direct.
Rule 58 Point of Commencement of Supply
The point of commencement of supply of energy to a
consumer shall be deemed to be the point at the
outgoing terminals of the cut-outs inserted by the
supplier in each conductor of every service line other
than an earthed or earthed neutral conductor or the
earthed external conductor of a concentric cable at the
consumer's premises.
Rule 61 Connection with Earth
1) The following provisions shall apply to the
connection with earth of systems at low
voltage in cases where the voltage between
phases or outers normally exceeds 125 volts
and of systems af medium voltage:
a) The neutral conductor of a three-phase
four-wire system, and the middle conductor
of a two-phase three-wire system shall
be earthed by not less than two separate
and distinct connections with earth both
at the generating station and at the
substation. It may also be earthed at one
or more points along the distribution
system or service line in addition to any
connection with earth which may be at
the consumer's premises.
60
NATIONAL BUILDING CODE OF INDIA
b) In the case of a system comprising
electric supply lines having concentric
cables, the external conductor of such
cables shall be earthed by two separate
and distinct connections with earth.
c) The connection with earth may include a
link by means of which the connection
may be temporarily interrupted for
the purpose of testing or for locating a
fault.
d) i) In a direct current three-wire system
the middle conductor shall be earthed
at the generating station only, and the
current from the middle conductor to
earth shall be continuously recorded
by means of recording ammeter, and
if at any time the current exceeds one
thousandth part of the maximum
supply current, immediate steps shall
be taken to improve the insulation of
the system.
ii) Where the middle conductor is
earthed by means of a circuit-breaker
with a resistance connected in parallel,
the resistance shall not exceed 10
ohms and on the opening of the circuit-
breaker, immediate steps shall be
taken to improve the insulation of the
system, and the circuit-breaker shall
be re-closed as soon as possible.
iii) The resistance shall be used only as
a protection for the ammeter in case
of earths on the system and until such
earths are removed, immediate steps
shall be taken to locate and remove
the earth.
e) In the case of an alternating current
system, there shall not be inserted in the
connection with earth and impedance
(other than that required solely for the
operation of switch gear or instrument),
cut-out or circuit-breaker, and the result
of any test made to ascertain whether the
current (if any) passing through the
connection with earth is normal, shall be
duly recorded by the supplier.
f) No person shall make connection with
earth by the aid of, nor shall be keep it in
contact with any water main not
belonging to him except with the consent
of the owner thereof and of the Inspector.
g) Alternating current systems which are
connected with earth as aforesaid may be
electrically interconnected, provided that
each connection with earth is bonded to
the metal sheathing and metallic
armouring (if any) of the electric supply
lines concerned.
2) The frame of every generator, stationary
motor, portable motor, and the metallic
parts (not intended as conductors) of all
transformers and any other apparatus used for
regulating or controlling energy and all
medium voltage energy consuming apparatus
shall be earthed by the owner by two separate
and distinct connections with earth.
3) All metal casings or metallic covering
containing or protecting any electric supply-
line or apparatus shall be connected with earth
and shall be so joined and connected across
all junction boxes and other openings as
to make good mechanical and electrical
connections throughout their whole length.
Provided that where the supply is at low
voltage, this sub-rule shall not apply to
isolated wall tubes or to brackets, electroliers,
switches, ceiling fans or other fittings (other
than portable hand lamps and portable and
transportable apparatus) unless provided with
earth terminal.
Provided further that where the supply is at
low voltage and where the installations are
either new or renovated all plug sockets shall
be of the three-pin type, having permanently
and efficiently earthed.
The sub-rule shall come into force
immediately in the case of new installations
and in the case of existing installations the
provisions of this sub-rule shall be complied
with before the expiry of a period of two years
from the commencement of those rules.
4) All earthing systems shall before electric
supply lines or apparatus are energized, be
tested for electrical resistance to ensure
efficient earthing.
5) All earthing systems belonging to the supplier
shall, in addition, be tested for resistance on
dry day during the dry season not less than
once every two years.
6) A record of every earth test made and the
result thereof shall be kept by the supplier for
a period of not less than two years after the
day of testing and shall be available to the
Inspector or any officer appointed to assist
the Inspector and authorised under sub-rule
(2) of Rule 4A when required.
Rule 64 Use of Energy at High and Extra-High Voltage
1) The Inspector shall not authorise the supplier
to commence supply, or where the supply has
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
61
been discontinued for a period of one year
and above, to re-commence the supply at high
or extra-high voltage to any consumer unless:
a) all conductors and apparatus intended for
use at high or extra-high voltage and
situated on the premises of the consumer
are inaccessible except to an authorised
person and all operations in connection
with the said conductors and apparatus are
carried out only by an authorised person;
b) the consumer has provided and agrees to
maintain a separate building or a locked
weather-proof and fire-proof enclosure
of agreed sign and location, to which the
supplier shall at all times have access for
the purpose of housing is high or extra-
high voltage apparatus and metering
equipment, or where the provision
of a separate building or enclosure
is impracticable, the consumer has
segregated the aforesaid apparatus of the
supplier from any other part of his own
apparatus:
Provided that such segregation shall be
by the provision of fire-proof walls, if
the Inspector considers it to be necessary:
Provided further that in the case of an
out-door installation the consumer shall
suitably segregate the aforesaid apparatus
belonging to the supplier from his own
to the satisfaction of the Inspector.
c) all pole type substations are constructed
and maintained in accordance with
Rule 69.
2) The following provisions shall be observed
where energy at high or extra-high voltage is
supplied, converted, transformed or used:
a) All conductors or live parts of any
apparatus shall ordinarily be inaccessible.
b) All windings, at high or extra-high
voltage of motors or other apparatus
within reach from any position in which
a person may require to be suitably
protected so as to prevent danger.
c) Where transformer or transformers are
used, suitable provision shall be made,
either by connecting with earth voltage
or otherwise, to guard against danger by
reason of the said circuit becoming
accidentally charged above its normal
voltage by leakage from or contact with
the circuit at the higher voltage.
d) i) A substation or switch station with
apparatus having more than
2 000 litres of oil shall not ordinarily
be located in the basement where
proper oil drainage arrangements
cannot be provided,
ii) Where a substation or switch station
with apparatus having more than
2 000 litres of oil is installed whether
indoors or outdoors, the following
measures shall be taken, namely:
(a) baffle walls shall be erected
between the apparatus containing
more than 2 000 litres of oil
and the adjacent apparatus to
prevent spread of fire and avoid
damage;
(b) a drain valve of adequate size
which shall be capable of being
safely operated even when the
apparatus has caught fire shall be
provided, and such a valve shall
be easily accessible to being
operated and at the same time not
susceptible to being operated
inadvertently;
(c) the drain valve shall let out the
oil to a covered drainage system
which shall take away the oil to
a place away from the danger
zone;
iii) the above measures shall be taken in
addition to other fire protection
arrangements to be provided for
quenching the fire in the apparatus;
iv) cable trenches inside the substations
and switch stations containing cables
shall be filled with sand, pebbles or
similar non-inflammable materials,
or completely covered with non-
inflammable slabs.
e) Unless the conditions are such that all the
conductors and apparatus for use at high
or extra-high voltage may be made dead
at the same time for other work thereon,
the said conductors and apparatus shall
be so arranged that they may be made
dead in sections, and that work on any
section made dead may be carried on by
an authorised person without danger.
f) Only persons authorised under sub-rule
(1 ) of Rule 3 carry out the work on live
lines and apparatus.
g) Adequate precautions shall be taken to
prevent unauthorised access to any
part of the installation designed to be
electrically charged at high or extra-high
voltage.
62
NATIONAL BUILDING CODE OF INDIA
ANNEX C
[Clause 4.2.4(b)]
AREA REQUIRED FOR TRANSFORMER ROOM AND SUBSTATION
FOR DIFFERENT CAPACITIES
C-l The requirement for area for transformer room and substation for different capacities of transformers is
given below for guidance:
Total Transformer Total Substation Area (In Coming, Suggested Minimum
Room Area, HV, MV Panels, Transformer Roof but Face Width
Minimum, m Without Generators), Minimum m
(3)
SI
Capacity of
No.
Transformer(s)
kVA
(1)
(2)
i)
1x160
ii)
2x 160
iii)
1x250
iv)
2x250
v)
1x400
vi)
2x400
vii)
3x400
viii)
2x500
ix)
3x500
x)
2x630
xi)
3x630
xii)
2x800
xiii)
3x800
xiv)
2 x 1 000
xv)
3 x 1 000
(4)
(5)
14.0
28.0
15.0
30.0
16.5
33.0
49.5
36.0
54.0
36.0
54.0
39.0
58.0
39.0
58.0
90
118
91
121
93
125
167
130
172
132
176
135
181
149
197
9.0
13.5
9.0
13.5
9.0
13.5
18.0
14.5
19.0
14.5
19.0
14.5
14.0
14.5
19.0
NOTES
1 The above dimensions are overall area required for substation excluding generating set.
2 The clear height required for substation equipment shall be minimum of 3 .0 m below the soffit of the beam.
ANNEX D
[Clause 4.2.4(j)]
ADDITIONAL AREA REQUIRED FOR GENERATOR IN ELECTRIC SUBSTATION
D-l The requirement of additional area for generator in electric substation for different capacities of generators
is given below for guidance:
UNo.
Capacity
kW
(1)
(2)
i)
25
ii)
48
iii)
100
iv)
150
v)
248
vi)
350
vii)
480
viii)
600
ix)
800
x)
1000
xi)
1250
xii)
1600
Area
2
m
(3)
Clear Height below the Soffit of the Beam
m
(4)
56
56
65
72
100
100
100
110
120
120
120
150
3.6
3.6
3.6
4.6
4.6
4.6
4.6
4.6
4.6
4.6
4.6
4.6
NOTE — The area and height required for generating set room given in the above table are for general guidance only and may be
finally fixed according to actual requirements.
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
63
ANNEX E
(Clause 9.3.2.6)
FORM OF COMPLETION CERTIFICATE
I/We certify that the installation detailed below has been installed by me/us and tested and that to the best of my/
our knowledge and belief, it complies with Indian Electricity Rules, 1956.
Electrical Installation at
Voltage and system of supply
Particulars of Works:
a) Internal Electrical Installation
No. Total Load Type of system of wiring
i) Light point
ii) Fan point
iii) Plug point
3-pin 6 A
3-pin 16 A
b) Others Description hp/kW Type of starting
1) Motors:
i)
ii)
iii)
2) Other plants:
c) If the work involves installations of
over head line and/or underground cable
1) i) Type and description of overheadline.
ii) Total length and number of spans,
iii) No. of street lights and its description.
2) i) Total length of underground cable and its size:
ii) No. of joints:
End joint:
Tee joint:
Straight through joint:
Earthing:
i) Description of earthing electrode
ii) No. of earth electrodes
iii) Size of main earth lead
Test Results:
a) Insulation Resistance
i) Insulation resistance of the whole system of conductors to earth Megaohms.
ii) Insulation resistance between the phase conductor and neutral
Between phase R and neutral Megaohms.
Between phase Y and neutral Megaohms.
Between phase B and neutral Megaohms.
iii) Insulation resistance between the phase conductors in case of polyphase supply.
Between phase R and phase Y Megaohms
Between phase Y and phase B Megaohms
Between phase B and phase R Megaohms
64 NATIONAL BUILDING CODE OF INDIA
b) Polarity test:
Polarity of non-linked single pole branch switches
c) Earth continuity test:
Maximum resistance between any point in the earth continuity conductor including metal
conduits and main earthing lead Ohms.
d) Earth electrode resistance:
Resistance of each earth electrode.
i) Ohms.
ii) Ohms.
iii) Ohms.
iv) Ohms.
e) Lightning protective system.
Resistance of the whole of lightning protective system to earth before any bonding is effected
with earth electrode and metal in/on the structure Ohms.
Signature of Supervisor
Name and Address
Signature of Contractor
Name and Address
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and 'accepted standards'
in the fulfilment of the requirements of the Code. The
latest version of a standard shall be adopted at the time
of the enforcement of the Code. The standards
listed may be used by the Authority as a guide in
conformance with the requirements of the referred
clauses in the Code.
Title
(1) 8270 Guide for preparation of
diagrams, charts and tables
for electrotechnology: Part 1
Definitions and classification
Electrotechnical vocabulary:
Lighting, Section 3 Lamps
and auxiliary apparatus
(Part 17) : 1979 Switchgear and controlgear
(first revision)
Electrical cables (first
revision)
Generation, transmission and
distribution of electricity —
General
12032 Graphical symbols for
IS No.
8270
(Part 1) : 1976
1885
(Partl6/Sec3)
1967
(Part 32) : 1993
(Part 78): 1993
IS No.
(Part 6): 1987
(Part 7): 1987
(2) 7752
(Part 1) : 1975
(3) 5216
(Part 1) : 1982
(Part 2) : 1982
(4) 10118
(Part 2) : 1982
(5) 1646 : 1997
Title
diagrams in the field of
electrotechnology:
Protection and conversion of
electrical energy
Switchgear, controlgear and
protective devices
Guide for improvement of
power factor in consumer
installation: Part 1 Low and
medium supply voltages
Recommendations on safety
procedures and practices in
electrical work:
General (first revision)
Life saving techniques (first
revision)
Code of practice for selection,
installation and maintenance
of switchgear and controlgear:
Part 2 Selection
Code of practice for fire
safety of buildings (general):
Electrical installations
(second revision)
PART 8 BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
65
IS No,
Title
IS No.
(6)
732 : 1989
Code of practice for electrical
(Part4/Secl):
wiring installations (third
1993
revision)
1255 : 1983
Code of practice for
(Part 5/Sec 1) :
installation and maintenance
1993
of power cables (up to and
including 33 kV rating)
(second revision)
(12) 3961
(7)
13947:1993
Specification for low- voltage
switchgear and controlgear
(Part 1) : 1967
(8)
2148 : 1981
Specification for flame-proof
enclosures of electrical
(Part 2): 1967
apparatus (second revision)
(9)
5578 : 1985
Guide for marking of
(Part 3) : 1968
insulated conductors (first
(Part 5) : 1968
revision)
(10]
) 1777 : 1978
Industrial luminaire with
metal reflectors (first
revision)
(13) 2086: 1993
2206
Flameproof electric lighting
fittings:
13703
(Parti): 1984
Well-glass and bulkhead
types (first revision)
(Part 1) : 1993
(Part 2): 1976
Fittings using glass tubes
3287 : 1965
Industrial lighting fittings
with plastic reflectors
(14) 2672: 1966
3528 : 1966
Waterproof electric lighting
fittings
4347 : 1967
3553 : 1966
Specification for watertight
electric lighting fittings
6665 : 1972
4012 : 1967
Specification for dust-proof
electric lighting fittings
8030 : 1976
4013 : 1967
Dust-tight electric lighting
fittings
(15) 732:1989
5077 : 1969
Decorative lighting outfits
10322 (Part 5/
Luminaires: Part 5 Particular
(16) 4648 : 1968
Sec 5) : 1987
requirements, Section 5 Flood
lights
(17) 900: 1992
(11) 8828: 1996
Electrical accessories —
Circuit-breakers for over
current protection for
household and similar
(18) 2412: 1975
installations (second revision)
13947
Specification for low- voltage
switchgear and controlgear:
(19) 2667: 1988
(Part 1) : 1993
General rules
(Part 2): 1993
Circuit-breakers
3419: 1989
(Part 3) : 1993
Switches, disconnectors,
switch disconnectors and fuse
9537
combination units
Title
Contactors and motor-starters,
Section 1 Electro-technical
contactors and motor starters
Control circuit devices and
switching elements, Section 1
Electro-technical control
circuit devices
Recommended current
ratings for cables:
Paper insulated lead sheathed
cables
PVC insulated and PVC
sheathed heavy duty cables
Rubber insulated cables
PVC insulated light duty
cables
Specification for carriers and
bases used in rewirable type
electric fuses for voltages
upto 650 V (third revision)
LV fuses for voltages not
exceeding 1 000 V ac or
1 500 dc : Part 1 General
requirements
Code of practice for library
lighting
Code of practice for hospital
lighting
Code of practice for industrial
lighting
Specification for luminaires
for hospitals
Code of practice for electrical
wiring installations (third
revision)
Guide for electrical layout in
residential buildings
Code of practice for
installation and maintenance
of Induction motors (second
revision)
Link clips for electrical
wiring (first revision)
Fittings for rigid steel
conduits for electrical wiring
(first revision)
Fittings for rigid non-metallic
conduits (second revision)
Conduits for electrical
installations:
66
NATIONAL BUILDING CODE OF INDIA
IS No.
(Part 1) : 1980
(Part 2): 1981
(Part 3): 1983
14772 : 2000
(20) 1913
(Part 1) : 1978
(21) 1258 : 1987
(22) 418 : 1978
1534
(Parti): 1977
1569 : 1976
2215 : 1983
2418
(Part 1) : 1977
(Part 2): 1977
(Part 3) : 1977
Title
General requirements
Rigid steel conduits
Rigid plain conduits of
insulating materials
Specification for accessories
for household and similar
fixed electrical installations
General and safety
requirements for luminaires:
Part 1 Tubular fluorescent
lamps {second revision)
Bayonet lamp holders (third
revision)
Tungsten filament general
service electric lamps (third
revision)
Ballasts for fluorescent
lamps: Part 1 For switch start
circuits (second revision)
Capacitors for use in tubular
fluorescent high pressure
mercury and low pressure
sodium vapour discharge
lamp circuit (first revision)
Specification for starters for
fluorescent lamps (third
revision)
Specification for tubular
fluorescent lamps for general
lighting service:
Requirements and tests (first
revision)
Standard lamp data sheets
(first revision)
Dimensions of G-5 and G-13
lc-pin caps (first revision)
IS No.
(Part 4): 1977
3323 : 1980
3324 : 1982
9900
(Part 1) : 1981
(Part 2) : 1981
(Part 3) : 1981
(Part 4): 1981
(23) 374 : 1979
(24) 3043 : 1987
(25) 8623
(Part 1) : 1993
(26) 10028
(Part 2): 1981
11353: 1985
(27) 2309 : 1989
Title
Go and no-go gauges for G-5
and G-13 lc-pin caps (first
revision)
Bi-pin landholders for
tubular fluorescent lamps
(first revision)
Holders for starters for
tubular fluorescent lamps
(first revision)
Basic environmental testing
procedures for electronic
and electrical items:
General
Cold test
Dry heat test
Damp test (steady state)
Electric ceiling type fans and
regulators (third revision)
Code of practice for earthing
Specification for low-voltage
switchgear and controlgear
assemblies: Part 1
Requirements for type-tested
and partially type-tested
assemblies (first revision)
Code of practice for selection,
installation and maintenance
of transformers: Part 2
Installation
Guide for uniform system of
marking and identification of
conductors and apparatus
terminals
Code of practice for the
protection of buildings and
allied structures against
lightning (second revision)
PARTS BUILDING SERVICES — SECTION 2 ELECTRICAL AND ALLIED INSTALLATIONS
67
NATIONAL BUILDING CODE OF INDIA
PART 8 BUILDING SERVICES
Section 3 Air Conditioning, Heating and Mechanical Ventilation
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 PLANNING DESIGN CRITERIA
4 DESIGN OF AIR CONDITIONING
5 NOISE AND VIBRATION CONTROL
6 MECHANICAL VENTILATION (FOR NON AIR CONDITIONED AREAS)
AND EVAPORATIVE COOLING
7 UNITARY AIR CONDITIONER
8 SPLIT AIR CONDITIONER
9 PACKAGED AIR CONDITIONER
10 HEATING
1 1 SYMBOLS, UNITS, COLOUR CODE AND IDENTIFICATION OF SERVICES
12 ENERGY CONSERVATION, ENERGY MANAGEMENT, AUTOMATIC
CONTROLS AND BUILDING MANAGEMENT SYSTEM
13 INSPECTION, COMMISSIONING AND TESTING
LIST OF STANDARDS
5
5
7
12
26
30
35
36
37
38
39
40
46
48
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
This Section deals with various aspects of installation of air conditioning equipments and systems in buildings.
The aspects covered include design goals and criteria, design of systems, performance requirements, available
system options, pre-planning requirements, noise and vibration, safety aspects, energy conservation and
management, building management systems and inspection, installation, testing and commissioning requirements.
Though all aspects of the air conditioning, heating and mechanical ventilation plant have been touched upon in
this revision, care has been taken right through to look at them from the specific point of view of how they can
be fashioned to impact beneficially on the building as a whole. Thus, topics like pre-planning, safety requirements,
adequate provisions for maintenance, energy management, conservation strategies and noise pollution
considerations have qualified for special attention.
Space requirements for various air conditioning systems vary considerably with the system adopted. In the
scenario of ever-increasing available system options, it has become all the more necessary to consult an air
conditioning engineer in this connection at the stage of pre-planning.
i
Weather data has now been included for as many as 58 stations based on data obtained from India Meteorological
Department, Government of India. Till such information is collected for other cities, it is recommended that
design work in these cities may be carried out according to the present (local) practice.
The first version of this Part was prepared in 1970 which was subsequently revised in 1983. As a result of
experience gained in implementation of 1983 version of this Section and feedback received, a need to revise this
Part was felt.
This revision has therefore been prepared. The significant modifications made in this revision include the following:
a) Definitions of several new terms like ozone depletion potential, global warming potential, indoor air
quality, sick building syndrome, buildings related illnesses and thermal energy storage have been included.
b) A new clause on design criterion has been incorporated.
c) Tndoor air quality' has been included as one of the factors that need to be controlled in the conditioned
space.
d) For large and multi-storeyed buildings, independent air handling unit rooms have been recommended
for each floor.
e) Inside design conditions for various applications have been included; they replace earlier Table 2 and
Table 3.
f) The text on minimum outside fresh air has been revised in the light of currently accepted international
norms. Recommended values for outside air requirements for ventilation purposes have been furnished
for a wider variety and a larger number of applications.
g) New details have been added on temperature, humidity, and vibration and iioise.
h) Application considerations, covering a wide variety of commercial applications, offices, hotels,
restaurants, computer rooms, etc, have now been given in more details.
j) A new clause on statutory regulation/safety considerations has now been included.
k) Under the clause on design considerations, various system options available have been described,
m) The characteristics and application of options available in piping, water distribution systems and piping
layout have been given prominently.
n) The text on air filters has been revised; focus is now on the approach to filtration in preference to a
detailed description of ever increasingly available option of filter types.
p) The clause on energy conservation and energy management has been thoroughly revised. The concepts
like energy targets, demand targets and consumption targets; the factors to be considered in system
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION 3
design that influence energy aspects ; the need for analysis of operation of systems during various seasons
of the year, and the need to incorporate energy recovery strategies have been incorporated in this clause,
q) 'Automatic Controls' given in the 1983 version has now been replaced by Building Management System,
which addresses not only the control function, but also has a telling impact on operation and maintenance
as well, most importantly on the opportunities afforded to implement various energy conservation
strategies,
r) The text on packaged air conditioners and room air conditioners has been revised and elaborated,
s) The text on heating has been completely revised,
t) The text had been thoroughly revised and additional details have been included under Symbols, Units,
Colour Code and Identification of Services; Pipe Work Services; Duct Work Services; Valve Labels
and Charts; and Inspection, Commissioning and Testing,
u) List of various parameters to be checked for performance of air handling unit, hydronic system balancing,
and finally, the hand-over procedure, have been given.
This revision aims to make a difference in the quality of environment and in building usage, in response to
growing concerns and expectations in with regard to indoor air quality, energy conservation, environmental
impact and building safety.
The provisions on natural ventilation are given in Part 8 'Building Services, Section 1 Lighting and Ventilation'.
The provisions of this Section are without prejudice to the various Acts, Rules and Regulations including the
Factories Act, 1948 and the rules and regulations framed thereunder.
The information contained in this Section is based largely on the following Indian Standards:
IS No. Title
659 : 1964 Safety code for air conditioning (revised)
1 39 1 Specification for room air conditioners:
(Part 1) : 1992 Unitary air conditioners (second revision)
(Part 2) : 1992 Split air conditioners (second revision)
2379 : 1990 Colour code for identification of pipelines (first revision)
3315 : 1994 Specification for evaporative air coolers (desert coolers) (second revision)
7896 : 2001 Data for outside design conditions for air conditioning for Indian cities (first revision)
8148 : 2003 Specification for packaged air conditioners (first revision)
Assistance has also been derived from the following publications in preparation of this Section:
BS 5720 : 1979 Code of practice for mechanical ventilation and air conditioning in building
Guidelines, Standards and Handbooks of American Society of Heating Refrigerating and Air Conditioning
Engineers
Handbooks of Indian Society of Heating, Refrigerating and Air Conditioning Engineers
All standards, whether given herein above or cross-referred to in the main text of this Section, are subject to
revision. The parties to agreement based on this Section are encouraged to investigate the possibility of applying
the most recent editions of the standards.
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 8 BUILDING SERVICES
Section 3 Air Conditioning, Heating and Mechanical Ventilation
1 SCOPE
This Section covers the design, construction and
installation of air conditioning and heating systems and
equipment installed in buildings for the purpose
of providing and maintaining conditions of air
temperature, humidity, purity and distribution suitable
for the use and occupancy of the space.
2 TERMINOLOGY
2.0 For the purpose of this Section the following
definitions shall apply.
2.1 Air Conditioning — The process of treating air so
as to control simultaneously its temperature, humidity,
purity, distribution and air movement and pressure to
meet the requirements of the conditioned space.
2.2 Atmospheric Pressure — The weight of air
column on unit surface area of earth by atmospheric
column. At sea level, the standard atmospheric or
barometric pressure is 760 mm of mercury (1 033 mm
of water column/101.325 kPa).
Generally atmospheric pressure is used as a datum for
indicating the system pressures in air conditioning and
accordingly, pressures are mentioned above the
atmospheric pressure or below the atmospheric pressure
considering the atmospheric pressure to be zero. A 'LP
tube manometer will indicate zero pressure when
pressure measured is equal to atmospheric pressure.
2.3 Buildings Related Illnesses (BRI) — The illness
attributed directly to the specific air-borne building
contaminants like the outbreak of the Legionnaire's
disease after a convention and sensitivity pneumonitis
with prolonged exposure to the indoor environment
of the building.
Some of the other symptoms relating to BRI are
sensory irritation of eyes, ears and throat, skin irritation,
headache, nausea, drowsiness, asthma like symptoms
in non-asthmatic persons. The economic consequences
of BRI is decreased productivity, absenteeism and the
legal implications if occupants IAQ complaints are left
unresolved.
2.4 Dewpoint Temperature — The temperature at
which condensation of moisture begins when the air is
cooled at same pressure.
2.5 Dry-Bulb Temperature — The temperature of
the air, read on a thermometer, taken in such a way as
to avoid errors due to radiation.
2.6 Duct System — A continuous passageway for the
transmission of air which, in addition to the ducts, may
include duct fittings, dampers, plenums, and grilles and
diffusers.
2.7 Enthalpy — A thermal property indicating the
quantity of heat in the air above an arbitrary datum, in
kilo Joules per kg of dry air (or in Btu per pound of
dry air).
2.8 Evaporative Air Cooling — The evaporative air
cooling application is the simultaneous removal of
sensible heat and the addition of moisture to the air.
The water temperature remains essentially constant at
the wet-bulb temperature of the air.
2.9 Fire Damper — A closure which consists of a
normally held open damper installed in an air
distribution system or in a wall or floor assembly and
designed to close automatically in the event of a fire
in order to maintain the integrity of the fire separation.
2.10 Fire Separation Wall — The wall providing
complete separation of one building from another or
part of a building from another part of the same
building to prevent any communication of fire or heat
transmission to wall itself which may cause or assist
in the combustion of materials of the side opposite to
that portion which may be on fire.
2.11 Global Warming Potential (GWP) — The
potential of a refrigerant to contribute to global
warming.
Global warming can make our planet and its climate
less hospitable and more hostile to human life, thus
necessitating reduction in emission of green house
gases such as C0 2 , SO x , NO x and refrigerants. Long
atmospheric life time of refrigerants results in global
warming unless the emissions are controlled.
GWP values of some of the refrigerants are given
below:
SI No.
Refrigerant
GWP Values
(1)
(2)
(3)
i)
R-12
10600
ii)
R-22
1900
iii)
R-134a
1600
iv)
R-123
120
v)
R-407c
1980
vi)
R-407a
2 340
vii)
R-410a
2 340
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION
The values indicated above are for an integration period
of 100 years.
2.12 Hydremic Systems — The water systems that
convey heat to or from a conditioned space or process
with hot or chilled water. The water flows through
piping that connects a chiller or the water heater to
suitable terminal heat transfer units located at the space
or process.
2.13 Indoor Air Quality (IAQ) — Air quality that
refers to the nature of conditioned air that circulates
throughout the space/area where one works or lives,
that is, the air one breathes when indoors.
It not only refers to comfort which is affected by
temperature, humidity, air movement and odours but
also to harmful biological contaminants and chemicals
present in the conditioned space. Poor IAQ may be
serious health hazard. Carbon dioxide has been
recognized as the surrogate ventilation index.
2.14 Infiltration/Exfiltration — The phenomenon
of outside air leaking into/out of an air conditioned
space.
2.15 Ozone Depletion Potential (ODP) — The
potential of refrigerant or gases to deplete the ozone
in the atmosphere.
The ODP values for various refrigerants are as given
below:
R-ll
R-12
R-22
R-123
R-134a
R-407a
R-407c
R-410a
1.000
0.820
0.050
0.012
0.000
0.000
0.000
0.000
Due to high ODP of R- 1 1 , R- 1 2 and R-22, their use in
the air conditioning and refrigeration is being phased-
out. R-123 is also in the phase-out category of
refrigerants.
2.16 Plenum — An air compartment or chamber to
which one or more ducts are connected and which
forms part of an air distribution system.
The pressure drop and air velocities in the plenum
should be low. Generally, the velocity in plenum should
not exceed 1.5 m/s to 2.5 m/s.
2.17 Positive Ventilation — The supply of outside
air by means of a mechanical device, such as a fan.
2.18 Psychrometry — The science involving
thermodynamic properties of moist air and the effect
of atmospheric moisture on materials and human
comfort. It also includes methods of controlling thermal
properties of moist air.
2.19 Psychrometric Chart — A chart graphically
representing the thermodynamic properties of moist
air.
2.20 Recirculated Air — The return air that has been
passed through the conditioning apparatus before being
re-supplied to the space.
2.21 Refrigerant — The fluid used for heat transfer
in a refrigerating system, which absorbs heat at a low
temperature and low pressure of the fluid and rejects
heat at a higher temperature and higher pressure of
the fluid, usually involving changes of state of the
fluid.
2.22 Relative Humidity — Ratio of the partial
pressure of actual water vapour in the air as compared
to the partial pressure of maximum amount of water
that may be contained at its dry bulb temperature.
When the air is saturated, dry-bulb, wet-bulb and
dewpoint temperatures are all equal, and the relative
humidity is 100 percent.
2.23 Return Air — The air that is collected from the
conditioned space and returned to the conditioning
equipment.
2.24 Shade Factor — The ratio of instantaneous heat
gain through the fenestration with shading device to
that through the fenestration.
2.25 Sick Building Syndrome (SBS) — A term,
which is used to describe the presence of acute non-
specific symptoms in the majority of people caused
by working in buildings with an adverse indoor
environment. It could be a cluster of complex irritative
symptoms like irritation of the eyes, blockened nose
and throat, headaches, dizziness, lethargy, fatigue
irritation, wheezing, sinusitis, congestion, skin rash,
sensory discomfort from odours, nausea, etc. These
symptoms are usually short-lived and experienced
immediately after exposure; and may disappear when
one leaves the building.
SBS is suspected when significant number of people
spending extended tirne in a building report or
experience acute on-site discomfort. The economic
consequences of SBS, like BRI, are decreased
productivity, absenteeism and the legal implications
if occupants IAQ complaints are left unresolved.
2.26 Smoke Damper — A damper similar to fire
damper, however, having provisions to close
automatically on sensing presence of smoke in air
distribution system or in conditioned space.
2.27 Static Pressure — The pressure that is required
to be created by the fan over the atmospheric pressure
NATIONAL BUILDING CODE OF INDIA
to overcome the system resistances such as resistances
in ducts, elbows, filters, dampers, heating/cooling coils,
etc.
Static pressure is measured by a U tube manometer
relative to the atmospheric pressure, which is
considered as zero pressure. In exhaust systems, fan
produces negative static pressure, which is again used
to overcome the system resistances.
2.28 Supply Air — The air that has been passed
through the conditioning apparatus and taken through
the duct system and distributed in the conditioned
space.
2.29 Supply and Return Air Grilles and Diffusers
— Grilles and diffusers are the devices fixed in the air
conditioned space for distribution of conditioned
supply air and return of air collected from the
conditioned space for re-circulation.
2.30 Thermal Transmittance — Thermal transmission
per unit time through unit area of the given building
unit divided by the temperature difference between the
air or some other fluid on either side of the building
unit in 'steady state' conditions.
2.31 Thermal Energy Storage — Storage of thermal
energy, sensible, latent or combination thereof for use
in central system for air conditioning or refrigeration.
It uses a primary source of refrigeration for cooling
and storing thermal energy for reuse at peak demand
or for backup as planned.
2.32 Water Conditioning — The treatment of water
circulating in a hydronic system, to make it suitable
for air conditioning system due to its effect on the
economics of air conditioning plant.
Untreated water used in air conditioning system may
create problems such as scale formation, corrosion and
organic growth. Appraisal of the water supply source
including chemical analysis and determination of
composition of dissolved solids is necessary to devise
a proper water-conditioning programme.
2.33 Water Hardness — Hardness in water represented
by the sum of calcium and magnesium salts in water,
which may also include aluminium, iron, manganese,
zinc, etc. A chemical analysis of water sample should
provide number of total dissolved solids (TDS) in a
water sample in parts per million (ppm) as also
composition of each of the salts in parts per million.
Temporary hardness is attributed to carbonates and bi-
carbonates of calcium and/or magnesium expressed in
parts per million (ppm) as CaC0 3 . The remainder of
the hardness is known as permanent hardness, which
is due to sulphates, chloride, nitrites of calcium and/or
magnesium expressed in ppm as CaC0 3
Temporary hardness is primarily responsible for scale
formation, which results in poor heat transfer resulting
in increased cost of energy for refrigeration and air
conditioning. Permanent hardness (non-carbonate) is
not as serious a factor in water conditioning because it
has a solubility which is approximately 70 times greater
than the carbonate hardness. In many cases, water may
contain as much as 1 200 ppm of non-carbonate
hardness and not deposit a calcium sulfate scale.
The treated water where hardness as ppm of CaC0 3 is
reduced to 50 ppm or below, is recommenced for air
conditioning applications.
pK is a measure of acidity, pR is a negative logaritham
base 10, of the concentration of hydrogen ion in grams
per litre. Water having a pR of 7.0 is neutral, a pR
value less than 7 is acidic and pR value greater than 7
is alkaline. Water with pR less than 5 is quite acidic
and corrosive to ordinary metals and needs to be
treated.
2.34 Wet-Bulb Temperature — The temperature
registered by a thermometer whose bulb is covered by
a wetted wick and exposed to a current of rapidly
moving air of velocity not less than 4.5 m/s.
Wet-bulb temperature is indicated by a wet bulb
psychrometer constructed and used according to
specifications.
3 PLANNING DESIGN CRITERIA
3.1 Fundamental Requirements
3.1.1 The object of installing ventilation and air
conditioning facilities in buildings shall be to provide
conditions under which people can live in comfort,
work safely and efficiently.
3.1.2 Ventilation and air conditioning installation shall
aim at controlling and optimizing following factors in
the building:
a) Air purity and filtration,
b) Air movement,
c) Dry-bulb temperature,
d) Relative humidity,
e) Noise and vibration,
f) Energy efficiency, and
g) Fire safety.
3.1.3 All plans, specifications and data for air
conditioning, heating and mechanical ventilation
systems of all buildings and serving all occupancies
within the scope of the Code shall be supplied to the
Authority, where called for see Part 2 'Administration' .
3.1.4 The plans for air conditioning, heating and
mechanical ventilation systems shall include all
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION
details and data necessary for review of installation
such as:
a) building: name, type and location;
b) owner: name;
c) orientation: north direction on plans;
d) general plans: dimensions and height of all
rooms;
e) intended use of all rooms;
f) detail or description of wall construction,
including insulation and finish;
g) detail or description of roof, ceiling and floor
construction, including insulation and finish;
h) detail or description of windows and outside
doors, including sizes, weather stripping,
storm sash, sills, storm doors, etc;
j) internal equipment load, such as number of
people, motor, heaters and lighting load;
k) layout showing the location, size and
construction of the cooling tower (apparatus),
ducts, distribution system;
m) information regarding location, sizes and
capacity of air distribution system, refrigeration
and heating plant, air handling equipment;
n) information on air and water flow rates;
p) information regarding location and
accessibility of shafts;
q) information regarding type and location of
dampers used in air conditioning system;
r) chimney or gas vent size, shape and height;
s) location and grade of the required fire
separations;
t) water softening arrangement; and
u) information on presence of any chemical
fumes or gases.
3.2 Pre-planning
3.2.1 Design Considerations
3.2.1.1 Cooling load estimate shall be carried out prior
to installing air conditioning equipment. Calculation
of cooling load shall take into account the following
factors:
a) Recommended indoor temperature and
relative humidity;
b) Outside design conditions as specified in 4.4;
c) Details of construction and orientation of
exposures like roof, floor, walls, partition and
ceiling;
d) Fenestration area and shading factors;
e) Occupancy — Number of people and their
activity;
f) Ventilation — Requirement for fresh air;
g) Internal Load — Lighting and other heat
generating sources like computers, equipment
and machinery; and
h) Hours of use.
3.2.1.2 The design of system and its associated
controls shall also take into account the following:
a) Nature of application,
b) Type of construction of building,
c) Permissible control limits,
d) Control methods for minimizing use of
primary energy,
e) Opportunities for heat recovery,
f) Energy efficiency,
g) Filteration standard,
h) Hours of use,
j) Diversity factor, and
k) Outdoor air quality.
3.2.1.3 The operation of system in the following
conditions should be considered when assessing the
complete design:
a) Summer,
b) Monsoon,
c) Winter,
d) Intermediate seasons,
e) Night, and
f) Weekends and holidays.
3.2.1.4 Consideration should be given to changes in
building load and the system designed so that
maximum operational efficiency is maintained.
3.2.1.5 Special applications like hospitals/operating
theatres, computer rooms, clean rooms, laboratories,
libraries, museums/art galleries, sound recording
studios, shopping malls, etc shall be handled
differently.
3.2.2 Planning of Equipment Room for Central Air
Conditioning Plant
3.2.2.1 In selecting the location for plant room, the
aspects of efficiency, economy and good practice
should be considered ancf wherever possible it shall
be made contiguous with the building. This room shall
be located as centrally as possible with respect to the
area to be air conditioned and shall be free from
obstructing columns.
In the case of large installations (500 TR and above),
it is advisable to have a separate isolated equipment
room where possible. The clear headroom below soffit
of beam should be minimum 4.5 m for centrifugal
plants, and rninimum 3.6 m for reciprocating and screw
type plants.
NATIONAL BUILDING CODE OF INDIA
3.2.2.2 The floors of the equipment rooms should be
light coloured and finished smooth. For floor loading,
the air conditioning engineer should be consulted (see
also Part 6 'Structural Design, Section 1 Loads, Forces
and Effects').
3.2.2.3 Supporting of pipe within plant room spaces
should be normally from the floor. However, outside
plant room areas, structural provisions shall be made
for supporting the water pipes from the floor/ceiling
slabs. All floor and ceiling supports shall be isolated
from the structure to prevent transmission of
vibrations.
3.2.2.4 Equipment rooms, wherever necessary, shall
have provision for mechanical ventilation. In hot
climate, evaporative air-cooling may also be
considered.
3.2.2.5 Plant machinery in the plant room shall be
placed on plain/reinforced cement concrete foundation
and provided with anti-vibratory supports. All
foundations should be protected from damage by
providing epoxy coated angle nosing. Seismic
restraints requirement may also be considered.
3.2.2.6 Equipment room should preferably be located
adjacent to external wall to facilitate equipment
movement and ventilation.
3.2.2.7 Wherever necessary, acoustic treatment should
be provided in plant room space to prevent noise
transmission to adjacent occupied areas.
3.2.2.8 Air conditioning plant room should preferably
be located close to main electrical panel of the building
in order to avoid large cable lengths.
3.2.2.9 In case air conditioning plant room is located
in basement, equipment movement route shall
be planned to facilitate future replacement and
maintenance. Service ramps or hatch in ground floor
slab should be provided in such cases.
3.2.2.10 Floor drain channels or dedicated drain pipes
in slope shall be provided within plant room space for
effective disposal of waste water. Fresh water
connection may also be provided in the air conditioning
plant room.
3.2.2.11 Thermal energy storage
In case of central plants, designed with thermal energy
storage its location shall be decided in consultation with
the air conditioning engineer. The system may be located
in plant room, on rooftop, in open space near plant room
or buried in open space near plant room.
For roof top installations, structural provision shall take
into account load coming due to the same.
For open area surface installation horizontal or vertical
system options shall be considered and approach
ladders for manholes provided.
Buried installation shall take into account loads due to
movement above, of vehicles, etc.
Provision for adequate expansion tank and its
connection to thermal storage tanks shall be made.
3.2.3 Planning Equipment Room for Air Handling
Units and Package Units
3.2.3.1 This shall be located as centrally as possible
to the conditioned area and contiguous to the corridors
or other spaces for carrying air ducts. For floor loading,
air conditioning engineer shall be consulted (see also
Part 6 'Structural Design, Section 1 Loads, Forces and
Effects').
3.2.3.2 In the case of large and multistoried buildings,
independent air handling unit should be provided for
each floor. The area to be served by the air-handling
unit should be decided depending upon the provision
of fire protection measures adopted. Air handling unit
rooms should preferably be located vertically one
above the other.
3.2.3.3 Provision should be made for the entry of fresh
air. The fresh air intake shall have louvers having rain
protection profile, with volume control damper and
bird screen.
3.2.3.4 In all cases air intakes shall be so located as to
avoid contamination from exhaust outlets or to the
sources in concentrations greater than normal in the
locality in which the building is located.
3.2.3.5 Exterior openings for outdoor air intakes and
exhaust outlets shall preferably be shielded from
weather and insects.
3.2.3.6 No air from any dwelling unit shall be
circulated directly or indirectly to any other dwelling
unit, public corridor or public stairway.
3.2.3.7 All air handling rooms should preferably have
floor drains and water supply. The trap in floor drain
shall provide a water seal between the air conditioned
space and the drain line.
3.2.3.8 Supply/return air duct shall not be taken
through emergency fire staircase. However, exception
can be considered if fire isolation of ducts at wall
crossings is carried out.
3.2.3.9 Waterproofing of air handling unit rooms shall
be carried out to prevent damage to floor below.
3.2.3.10 The floor should be light coloured, smooth
finished with terrazzo tiles or the equivalent. Suitable
floor loading should also be provided after consulting
with the air conditioning engineer.
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION
3.2.3.11 Where necessary, structural design should
avoid beam obstruction to the passage of supply and
return air ducts. Adequate ceiling space should be
made available outside the air handling unit room
to permit installation of supply and return air ducts
and fire dampers at air handling unit room wall
crossings.
3.2.3.12 The air handling unit rooms may be
acoustically treated, if located in close proximity to
occupied areas.
3.2.3.13 Access door to air handling unit room shall
be single/double leaf type, air tight, opening outwards
and should have a sill to prevent flooding of adjacent
occupied areas. It is desired that access doors in air
conditioned spaces should be provided with tight
sealing, gaskets and self closing devices for air
conditioning to be effective.
3.2.3.14 It should be possible to isolate the air handling
unit room in case of fire. The door shall be fire resistant
and fire/smoke dampers shall be provided in supply/
return air duct at air handling unit room wall crossings
and the annular space between the duct and the wall
should be fire-sealed using appropriate fire resistance
rated material.
3.2.3.15 For buildings with large structural glazing
areas, care should be taken for providing fresh air
intakes in air handling unit rooms. Fire isolation shall
be provided for vertical fresh air duct, connecting
several air handling units.
3.2.4 Planning of Pipe Shafts
3.2.4.1 The shafts carrying chilled water pipes should
be located adjacent to air handling unit room or within
the room.
3.2.4.2 Shaft carrying condensing water pipes to
cooling towers located on terrace should be vertically
aligned.
3.2.4.3 All shafts shall be provided with fire barrier
at floor crossings (see Part 4 Tire and Life Safety')-
3.2.4.4 Access to shaft shall be provided at every
floor.
3.2.5 Planning for Supply Air Ducts and Return
Air
3.2.5.1 Duct supports, preferably in the form of angles
of mild steel supported using stud anchors shall be
provided on the ceiling slab from the drilled hole.
Alternately, duct supports may be fixed with internally
threaded anchor fastners and threaded rods without
damaging the slabs or structural members.
3.2.5.2 If false ceiling is provided, the supports for
the duct and the false ceiling, shall be independent.
Collars for grilles and diffusers shall be taken out only
after false ceiling/boxing framework is done and
frames for fixing grilles and diffusers have been
installed.
3.2.5.3 Where a duct penetrates the masonry wall it
shall either be suitably covered on the outside to isolate
it from masonry, or an air gap shall be left around it to
prevent vibration transmission. Further, where a duct
passes through a fire resisting compartment/barrier, the
annular space shall be sealed with fire sealant to prevent
smoke transmission (see also Part 4 'Fire and Life
Safety').
3.2.6 Cooling Tower
3.2.6.1 Cooling towers are used to dissipate heat from
water cooled refrigeration, air conditioning and
industrial process systems. Cooling is achieved by
evaporating a small proportion of recirculating water
into outdoor air stream. Cooling towers are installed
at a place where free flow of atmospheric air is
available.
3.2.6.2 Range of a cooling tower is defined as
temperature difference between the entering and
leaving water. Approach of the cooling tower is the
difference between leaving water temperature and the
entering air wet bulb temperature.
3.2.6.3 Types of cooling tower
3.2.6.3.1 Natural draft
This type of tower is larger than mechanical draft tower
as it relies on natural convection to obtain the air
circulation. A natural draft tower needs to be tall to
obtain the maximum chimney effect or rely on the
natural wind currents.
3.2.6.3.2 Mechanical draft
The fans on mechanical draft towers may be on the
inlet air side (forced draft) or exit air side (induced
draft). Typically, these have centrifugal or propeller
type fans, depending on pressure drop in tower,
permissible sound levels and energy usage requirement.
On the basis of direction of air and water flow,
mechanical draft cooling towers can be counter flow
or cross flow type.
3.2.6.4 Factors to be considered for cooling tower
selection are:
a) Design wet-bulb temperature and approach
of cooling tower.
b) Height limitation and aesthetic requirement.
c) Location of cooling tower considering
possibility of easy drain back from the
system.
d) Placement with regard to adjacent walls and
10
NATIONAL BUILDING CODE OF INDIA
windows, other buildings and effects of any
water carried over by the air stream.
e) Noise levels, particularly during silent hours
and vibration control.
f) Material of construction for the tower.
g) Direction and flow of wind.
h) Quality of water used for make-up.
j) Maintenance and service space,
k) Ambient air quality.
3.2.6.5 The recommended floor area requirement for
various types of cooling tower is as given below:
a) Natural draft cooling 0.15 to 0.20 m 2 /t
tower of refrigeration
b) Induced draft cooling 0.10 to 0.13 m 2 /t
tower of refrigeration
c) Fibre-reinforced 0.07 to 0.08 m 2 /t
plastic of refrigeration
3.2.6.6 Any obstruction to free flow of air to the
cooling tower shall be avoided.
3.2.6.7 Structural provision for the cooling tower shall
be taken into account while designing the building.
Vibration isolation shall be an important consideration
in structural design.
3.2.6.8 Special design requirements are necessary
where noise to the adjoining building is to be
avoided.
3.2.6.9 As given below, certain amount of water is
lost from circulating water in the cooling tower:
a) Evaporation loss — In a cooling tower, the
water is cooled by evaporating a part of the
circulating water into the air stream. The
amount of circulating water so evaporated
is called 'evaporation loss'. Usually it
is about 1 percent of the rate of water
circulation.
b) Drift loss — A small part of circulating water
is lost from the cooling tower as liquid
droplets entrained in the exhaust air stream.
Usually the drift loss is 0.1 percent to 0.2
percent of rate of water circulation.
c) Blow-down/bleed-qff — To avoid concentration
of impurities contained in the water beyond
a certain limit, a small percentage of water
in the cooling water system is often
purposely drained off or discarded. Such a
treatment is called 'blow-down' or 'bleed-
off . The amount of blow-down is usually
0.8 percent to 1 percent of the total water
circulation.
If simple blow-down is inadequate to control scale
formation, chemicals may be added to inhibit corrosion
and limit microbiological growth.
Provision shall be made to make-up for the loss of
circulating water.
3.2.6.10 Provision for make-up water tank to the
cooling tower shall be made. Make-up water tank to
the cooling tower shall be separate from the tank
serving drinking water.
3.2.6.11 Make-up water having contaminants or
hardness, which can adversely affect the refrigeration
plant life, shall be treated.
3.2.6.12 Cooling tower should be so located as to
eliminate nuisance from drift to adjoining structures.
3.2.7 Glazing
3.2.7.1 Glazing contributes significantly to heat
addition in air conditioned space; measures shall,
therefore, be adopted to minimize the gain.
3.2.7.2 While considering orientation of the building,
(see Part 8 'Building Services, Section 1 Lighting and
Ventilation') glazing in walls subjected to heavy sun
exposure shall be avoided. In case it is not possible to
do so, double glazing or heat resistant glass should be
used. Glazing tilted inward at about 12° also helps
curtail transmission of direct solar radiation through
the glazing.
3.2.7.3 Where sun breakers are used, the following
aspects shall be kept in view:
a) The sun breakers shall shade the maximum
glazed area possible, specially from the
altitude and azimuth angle of the sun, which
is likely to govern the heat load.
b) The sun breakers shall preferably be light and
bright in colour so as to reflect back as much
of the sunlight as possible.
c) The sun breakers shall preferably be 1 m away
from the wall face, with free ventilation,
particularly from top to bottom and are meant
for carrying away the heat which is likely to
get boxed between the sun breakers and the
main building face.
d) The sun breakers shall be installed as to have
minimum conduction of heat from sun
breakers to the main building.
3.2.7.4 Where resort is taken to provide reflecting
surfaces for keeping out the heat load, care should
be taken regarding the hazards to the traffic and
people on the road from the reflected light from the
surfaces.
3.2.7.5 Day light transmittance for various type of
glass is given in Table 1.
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION
11
Table 1 Day Light Transmittance for Various
Types of Glass
SI
Type of Glass
Visible Transmittance
No.
W/(m 2 °C)
(1)
(2)
(3)
i)
3 mm regular sheet or plate glass
0.86 to 0.91
ii)
3 mm grey sheet glass
0.31 to 0.71
iii)
5 mm grey sheet glass
0.61
iv)
5.5 mm grey sheet glass
0.14 to 0.56
6 mm grey sheet glass
0.52
v)
6 mm green/float glass
0.75
vi)
6 mm grey plate glass
0.44
vii)
6 mm bronze plate glass
0.49
viii)
13 mm grey plate glass
0.21
ix)
13 mm bronze plate glass
0.25
x)
Coated glasses (single, laminated,
insulating)
0.07 to 0.50
3.2.8 Roof Insulation
3.2.8.1 Under-deck or over-deck insulation shall be
provided for exposed roof surface using suitable
insulating materials. Over-deck insulation should be
properly waterproofed to prevent loss of insulating
properties.
3.2.8.2 The overall thermal transmittance from the
exposed roof should be kept as minimum as possible
and under normal conditions, the desirable value
should not exceed 0.58 W/(m 2 °C).
3.2.8.3 The ceiling surface of floors which are not
to be air conditioned may be suitably insulated to
give an overall thermal transmittance not exceeding
U6W/(m 2o C)
4 DESIGN OF AIR CONDITIONING
4.1 General
A ventilation and air conditioning system installed in
a building should clean, freshen and condition the air
within the space to be air conditioned. This can be
achieved by providing the required amount of fresh
air either to remove totally or to dilute odours, fumes,
etc (for example, from smoking). Local extract systems
may be necessary to remove polluted air from kitchens,
toilets, etc. Special air filters may be required to remove
contaminants or smells when air is recirculated.
It is desirable that access doors to air conditioned space
are provided with tight sealing gaskets and self closing
devices for air conditioning to be effective.
Positions of air inlets and extracts to the system are
most important and care should be taken in their
location. Consideration should be given to relatively
nearby buildings and any contaminated discharges
from those buildings. Inlets should not be positioned
near any flue outlets, dry cleaning or washing machine
extraction outlets, kitchen, water-closets, etc. When
possible, air inlets should be at high level so as to induce
air from as clean an area as possible. If low level intakes
are used, care should be taken to position them well
away from roadways and car parks.
4.2 Design Considerations
4.2.1 Types of System
Systems for air conditioning need to control temperature
and humidity within predetermined limits throughout
the year. Various types of refrigerating systems are
available to accomplish the tasks of cooling and
dehumidifying, which are an essential feature of air
conditioning. Systems for air conditioning may be
grouped as all-air type, air and water type, all water
type or unitary type.
4.2.1.1 All-air system
This type of air conditioning system provides
complete sensible and latent cooling, preheating and
humidification in the air supplied by the system. Most
plants operate on the recirculation principle, where a
percentage of the air is extracted and the remainder
mixed with incoming fresh air.
Low velocity systems may be used. High velocity
systems although require smaller ducts, are high on
fan energy, require careful acoustic treatment and
higher standards of duct construction.
4.2.1.1.1 Constant volume system
Accurate temperature control is possible, according to
the system adopted. Low velocity system variations
include dehumidification with return air bypass, and
multi-zone (hot deck/cold deck mixing). High velocity
system may be single or dual duct type.
4.2.1.1.2 Variable volume system
Most Indian air conditioning systems operate at partial
load for most of the year and the variable air volume
(VAV) system is able to reduce energy consumption
by reducing the supply air volume to the space under
low load conditions. The VAV system can be applied
to interior or perimeter zones, with common or separate
fans, with common or separate air temperature control.
The greatest energy saying associated with VAV
occurs at the perimeter zones, where variation in solar
and outside temperature allow the supply air quantity
to be reduced. Good temperature control is possible
but care should be taken at partial load to ensure
adequate fresh air supply and satisfactory control of
air distribution and space humidity.
4.2.1.2 Air and water system
Control of conditions within the space is achieved by
initial control of the supply air from a central plant but
with main and final control at a terminal unit within
the conditioned space. The supply air provides the
12
NATIONAL BUILDING CODE OF INDIA
necessary ventilation air and the small part of the total
conditioning. The major part of room load is balanced
by water through a coil in the terminal unit, which can
be either a fan coil unit or an induction unit.
Depending on the degree of control required, the water
circulating system can be either of two, three or four
pipe arrangement. With two pipe circulation a single
flow and a single return circulate chilled or hot water
as required. Such a system can only provide heating
or cooling to the system on a changeover basis, so it is
ineffective where wide modulations of conditions over
short periods are required. The installed cost however
is naturally the lowest of all the circulation systems.
The three pipe system is a way of overcoming the
disadvantages of the two pipe system without raising
the installed cost too high. In this system a separate
hot water flow and chilled water flow is taken to the
terminal units but a common return is taken from these
units to the plant room. The best system from a control
point of view is the four pipe system, where separate
hot water and chilled water supply and returns are taken
from the plant room to the terminal units. Although
the most expensive method of circulating the water, it
is the only satisfactory one, if reasonable control is
required throughout the year.
4.2.1.3 All water system
In the simplest layout, the fan coil units may be located
against an outside wall with a direct, fresh air
connection. A superior arrangement utilizes a ducted,
conditioned, fresh air supply combined with mechanical
extract ventilation,
Control of unit out put may be achieved by fan speed
and water flow/temperature control. Electric power is
required at each terminal unit.
Provision of variable volume water flow system for
chilled water circulation is recommended for varying
load conditions. This may be incorporated with the help
of constant volume primary chilled water circuit and
variable flow secondary chilled water circuit having
pumps with variable speed drives and pressure sensor
to control the speed. This system allows better control
on energy consumption under partial load conditions
due to diversity or seasonal load variations.
4.2.1.4 Unitary systems
Such systems are usually those incorporating one or
more units or packaged air conditioners having a direct
expansion vapour compression refrigeration system.
Similar units using chilled water from a central plant
would be designated fan coil systems. Most units are
only suitable for comfort applications but specially
designed units are also available for process and
industrial applications.
4.2.2 Vapour Compression Water Chiller
These normally contain the complete refrigerating
system, comprising the compressor, condenser,
expansion device and evaporator together with the
automatic control panel. The unit can be set down on
to a solid foundation on resilient mountings. Pipe
connection require flexible couplings; these should be
considered in conjunction with the design of the pump
mountings and the pipe supports.
Capacity control is normally arranged to maintain an
approximately constant temperature of the chilled
water leaving the evaporator. This may be adequate
for one or two packages, but a more elaborate central
control system may be necessary for a large number.
The design of the refrigeration control system should
be integrated, or be compatible, with the control system
for the heat transfer medium circulated to the air cooler.
It is normal for installation to have several water
chilling packages, both to provide for stand-by and
enable the cooling load to be matched with the
minimum consumption of power. Although most
packages can reduce capacity to match the cooling
demand, the consumption of the power per unit of
cooling increases; the resulting drop in efficiency is
most serious below one-third capacity.
Power consumption can be reduced by taking
advantage of a fall in the ambient temperature, which
permits a corresponding fall in the condensing
temperature and consequent reduction in the
compressor power. It is important, for economy in the
operation, that the optimum equipment selection and
design of the control system is achieved.
The classification of the water chilling packages is by
the type of compressor.
4.2.2.1 Centrifugal compressors
These compressors have an impeller that imparts to
the refrigerant vapour a high kinetic energy, which is
then transformed into pressure energy. For water
chilling applications, Compressors with one or two
stage of compression are used. Two stage units often
incorporate an interstate'economizer for improving
efficiency.
The compressor can be modulated down to approaching
10 percent of full load capacity, with some control of
the condensing pressure. Because of the nature of
compression process, the flow through the compressor
can become unstable if the compressor is called upon
to produce a pressure rise in excess of its design limits.
This phenomenon, known as surging, is a serious
problem but occurs only under a fault condition.
Typical faults are excessive fouling of the condenser,
a partial failure of the condenser coolant flow or an
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION
13
accumulation of a non-condensable gas (air) in the
condenser. Unchecked surging can lead to damage to
the compressor or its drive and does increase the noise
level.
The use of low pressure refrigeration to suit the
characteristics of the compressor in the smaller size
range, means that the evaporator operates at below
atmospheric pressure, thus a leak can draw in air and
atmospheric moisture. These should be prevented from
accumulating, since these interfere with the operation
of the plant and cause corrosion.
The compressors may be driven either directly by
electric motor or via a speed-increasing gear train.
Units are available in 'open' form, that is, compressor
and motor are separate items, or in semi-hermetic form
where the motor and compressor are contained in a
common pressure-tight casing that is bolted together.
The latter type eliminates the drive shaft gland seal (a
potential point of leakage), which is necessary on the
former.
Certain types of open centrifugal compressors could
conveniently be directly driven by a steam or gas
turbine. This arrangement could be advantageous when
the refrigeration plant forms part of total energy system.
The centrifugal compressor type water chilling
packages normally include a shell-and-tube water
cooled condenser and a flooded shell-and-tube
evaporator, but unit are also available incorporating
an air cooled condenser The expansion device is
commonly an electronic expansion valve or high
pressure float regulating valve.
4.2.2.2 Screw compressors
Two types of screw compressors are available, that
is, single and twin screw, and both are positive
displacement machines. Compression of the refrigerant
vapour is achieved by the progressive reduction of the
volume contained with in the helical flutes of the
cylindrical rotor(s) as they rotate.
Oil is injected into the rotor chamber for sealing and
lubrication purposes and is removed from the
refrigerant discharge gas in an oil separator before the
refrigerant passes on to the condenser. No oil separator
is 100 percent efficient and so a small quantity of oil
always passes through with the refrigerant. On systems
using a direct expansion evaporator the oil is trapped
in the evaporator and an oil recovery system is
necessary.
With some systems oil cooler is required in the oil
circulation system, to remove the heat gathered by the
oil during compression cycle. On other systems liquid
refrigerant is injected into the compressor to remove
the heat of compression instead of using the
conventional oil cooler. Such an arrangement can
impose a small penalty on the plant capacity.
The condenser most commonly used on packaged units
is the water cooled shell-and-tube type, but equipment
with air cooled condensers is also available. The
expansion device used will depend on the evaporator
type but it is often a electronic expansion valve (single
or in multiple) of conventional or modified form.
Screw compressors are available in open and semi-
hermetic form (see 4.2.2.1) and are generally coupled
direct to two-pole motors. The capacity of the
compressor can be modulated down to 10 percent of
full load capacity.
4.2.2.3 Reciprocating compressors
These are available in a wide range of sizes and designs.
They are almost invariably used in packages up to
120 TR cooling capacity.
Because the cylinders have automatic valves, a single
compressor may be used over wide range of operating
conditions with near optimum efficiency, whereas
other types of compressor require detailed modification
to give optimum efficiency at different conditions. This
is, however, of minor importance for normal air
conditioning duties.
Capacity control is achieved by making cylinders in-
operative, usually by propping open the suction valves,
thus, capacity reduction is in a series of steps rather
than by modulation. Typically, a four-cylinder
compressor would be unloaded in four steps. It is
therefore necessary to allow for this stepwise operation
in designing the chilled water temperature control
system.
The evaporator is normally of the dry expansion type,
to permit oil from the compressor to circulate round
the system with the refrigerant. Shell-and-tube water
cooled condensers are common, but any type of
condenser can be used. With air cooled condensers it
is normal practice to build the machine package so that
it may be located on the roof in a package including
the condenser.
It is common for the electric drive motors to be built
into the compressor assembly; this is known as a 'semi-
hermetic' drive to distinguish it from the 'hermetic',
in which the compressor and motor are enclosed within
a pressure vessel and cannot therefore be serviced.
The semi-hermetic compressor is more compact
and is quieter in operation than the 'open' drive
compressor, but involves a more difficult service
operation in the event of a motor failure. It gains in
reliability, however, by avoiding the shaft seal of the
'open' compressor.
14
NATIONAL BUILDING CODE OF INDIA
It is recommended that multiple hermetic or semi-
hermetic compressor unit should not be connected to
a common refrigerant system, as failure of one motor
can precipitate failure of the others. Separate refrigerant
circuits for each compressor should be used.
4.2.3 Absorption System
The absorption cycle uses a solution that by absorbing
the refrigerant replaces the function of the compressor.
The absorbent/refrigerant mixture is then pumped to a
higher pressure where the refrigerant is boiled off by
the application of heat, to be condensed in the
condenser.
Absorption machines are mostly used in liquid-chilling
applications. These are most suitable for hotels and
hospitals where steam is readily available from the
boilers.
4.2.3.1 Indirect firing
The lithium bromide/water absorption system can be
powered by medium or high temperature hot water and
low or medium pressure steam. Water is the refrigerant
and the lithium bromide the absorbent. The four
compartments enclosing the heat exchanger tube
bundles for the condenser, evaporator, generator and
absorber can be in a single or multiple pressure vessel
arrangement. The whole assembly has to be maintained
under a high vacuum, which is essential for the correct
functioning of the unit. Water and absorbent solutions
are circulated within the unit by electrically driven
pumps.
Capacity control down to 10 percent of full load
capacity is achieved by modulating the flow of the
heating medium in relation to the cooling demand.
There is some loss in performance at part load, which
can be compensated by refinements in the system
design and control.
4.2.3.2 Direct firing
Direct fired lithium bromide/water absorption plants
have become common, by incorporating precise
control of generator temperature necessary to avoid
crystallization.
Ammonia/water systems can be and are direct fired,
but are rarely used for water chilling duties except for
small sized units, which are installed outside the
building. There are two reasons or this, firstly capital
costs are higher and secondly the danger to personnel
in the event of leakage of the refrigerant.
Direct firing has the advantage that the losses in an
indirect heating system are avoided, but in an air
conditioning installation where a boiler system
is installed to provide heating, the advantage is
minimal.
4.3 System Design
4.3.1 Ductwork and Air Distribution
4.3.1.1 Materials
Ductwork is normally fabricated, erected and finished
to the requirements in accordance with accepted
standard [8-3(1)]. Designers should specify the
requirements as appropriate for the velocity and
pressure, and materials to be employed. Ductwork is
generally manufactured from galvanized steel sheet.
Ductwork may also be manufactured from aluminium
sheet for applications like operation theatres and
intensive care units where stringent cleanliness
standards are a functional requirement. Galvanized
steel sheets shall be in accordance with the accepted
standard [8-3(2)] whereas aluminium sheet shall be in
accordance with the accepted standard [8-3(3)]. Where
building materials, such as concrete or brick, are used
in the formation of airways, the interior surface should
be fire resistant, smooth, airtight and not liable to
erosion.
4.3.1.2 Ductwork design
Design calculations made to determine the size and
configuration of ductwork in respect of pressure drop
and noise generation should conform to standard
methods.
Ductwork design should also take into account the
recommendations for fire protection (see Part 4 'Fire
and Life Safety') relating to the design of air handling
system to fire and smoke control in buildings.
4.3.1.3 Layout consideration
When designing ductwork, consideration should be
given to:
a) Co-ordination with building, architectural and
structural requirements;
b) Co-ordination with other services;
c) Simplifying installation work;
d) Providing facilities and access for
commissioning and testing;
e) Providing facilities and access for operating
and maintenance;
f) Meeting fire and smoke control requirement;
and
g) Prevention of vibration and noise transmission
to the building/space.
4.3.2 Piping and Water Distribution System
4.3.2.1 Materials
Steel piping with welded or flanged joints is commonly
used. Flanges for flanged joints are welded to pipes.
The choice of materials or any installation will be
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION
15
governed by economic considerations, but care should
be taken to minimize the possibility of corrosion when
choosing material combinations.
4.3.2.2 Design principles
The system design should achieve the following two
main objectives:
a) A good distribution of water to the various
heat exchangers/cooling coils at all conditions
of load. This will be influenced by the method
chosen to control the heat transfer capacity
of air handling units. Failure to achieve good
hydraulic design may lead to difficulties with
system balancing. Adequate provision should
be made for measuring flow rates and pressure
differentials.
b) An economic balance between pipe size and
piping cost.
Excessive water velocities should be avoided, as they
may lead to noise at pipe junctions and bends.
When multiple water-chilling packages have to be used
in a large system, the control of the machines and the
arrangement of the water circulation should be
considered as an integrated whole. It is not possible to
obtain satisfactory result by considering control and
system design separately.
Temperature changes in the system lead to changes in
the volume of water, which has to be allowed to expand
into a suitable expansion tank. It is essential that the
point at which the expansion tank is connected into
the system be such that it is never shutoff. It is normal
practice to locate the expansion tank above the highest
point in the system, so that a positive pressure is
maintained when all the pumps are stopped; if this is
not possible, a closed tank can be installed at a lower
level and pressurized by an inert gas. Closed expansion
tank with air separator in the chilled water system helps
in improving the life and efficiency of chilled water
piping and heat exchange equipment.
For central chilled water air conditioning systems,
water is the usual heat transfer medium use to convey
the heat from the air-handling units to the primary
refrigerant in the evaporator. In certain special cases,
when temperatures lower than 5°C are required, an
anti-freeze such as ethylene glycol may be added to
depress the freezing point.
4.3.2.3 Piping design
The arrangement of the water piping will depend upon
the cooling or heating systems chosen as being the most
suitable for the building.
The water velocity normally used are dependent on
pipe size but are usually in the range 1 m/s to 3 m/s.
Main headers in the plant room are designed for very
low velocity around 1 m/s. Noise can be caused by
velocities in excess of 4 m/s but this is more likely to
be caused by air left in the pipes by inadequate venting.
Where materials other than steel are used, erosion can
occur at the higher velocities particularly if the water
is allowed to become acidic.
Friction factor in piping should not exceed 5 m of water
for 100 m of pipe length. The power consumed in
circulating the water around the system is proportional
to the pressure loss (due to friction) and the flow. It is
therefore an advantage to design system with a water
temperature rise say 5°C-7°C which results in
minimising the flow rate.
Air-conditioning system operate for a large part of the
time at less than the design load, and this means that
operating costs can be minimized if the water quantity
circulated can be reduced at partial load. This should
be done with variable speed pumping systems.
4.3.2.4 Layout considerations
The layout of the main pipe runs should be considered
in relation to the building structure, which will have to
support their weight and carry the imposed axial loads.
The positioning of expansion joints should be
considered in relation to the branches, which may only
accommodate small movements. The pumps should
not be subjected to excessive loads from the piping.
Provision should be made for venting air and any gas
formed by corrosion processes from the high points in
the system: failure to do this can lead to restricted water
flows and poor performance.
New systems invariably contain debris of one sort or
another left during construction, and this can cause
trouble by blocking pipes, control valves and pumps
if it is not removed during testing and commissioning.
Piping system should be designed to permit proper
cleaning and flushing and should include suitable
strainers at appropriate locations.
4.3.3 Thermal Insulation
4.3.3.1 Air conditioning and water distribution
systems carry chilled or heated fluids. Thermal
insulation is required to prevent undue heat gain or
loss and also to prevent internal and external
condensation; a vapour seal is essential if there is a
possibility of condensation within the insulating
materials.
4.3.3.2 The selection of suitable thermal insulating
materials requires that consideration be given to
physical characteristics as follows:
a) Fire Properties — Certain insulating
materials are combustible or may, in a fire,
16
NATIONAL BUILDING CODE OF INDIA
produce appreciable quantities of smoke and
noxious and toxic fumes.
b) Materials and their finishes should inherently
be proof against rotting, mould and fungal
growth, and attack by vermin, and should be
non-hygroscopic.
c) Material should not give rise to objectionable
odour at the temperature at which they are to
be used.
d) The material should not cause a known hazard
to health during application, while in use, or.
on removal, either from particulate matter or
from toxic fumes.
e) It should have a low thermal conductivity
throughout the entire working temperature
range.
f) It should be non-flammable and should not
support nor spread fire.
g) It should have good mechanical strength and
rigidity otherwise it would have to be cladded
for protection.
4.4 Design Conditions
4.4.1 Temperature
4.4.1.1 General consideration
Certain minimum temperatures may be required
depending on type of application and by local
regulations. Maximum permitted cooling temperatures
may be stipulated by relating to energy conservation.
From the comfort aspect, it is important to take into
account the effect of radiant temperature in fixing the
desired air temperatures to maintain comfortable
conditions.
When large windows/curtain walls are used, it may be
necessary to provide shading/north orientation to
protect the occupants from solar radiation and to reduce
the cooling load on the system. It is not practical to
fully compensate for solar heating, owing to its
intermittent nature, simply by lowering air temperature.
A person's heat loss, and hence his feeling of comfort,
depends not only on the air temperature but also on
the radiant heat gain, the air movement and the
humidity of the air. Many attempts have been made to
devise a single index that combines the effect of two
or more of these separate variables. In practice the
difference between these indices is small, provided the
various parameters do not vary beyond certain limits.
4.4.1.2 Design temperatures
It should be noted that, although comfort conditions
are established in terms of resultant temperature, the
design air temperature for air conditioning should be
as specified in this Section in terms of dry-bulb
temperature and relative humidity or wet-bulb
temperature.
4.4.2 Humidity
4.4.2.1 Comfort considerations
The controlled temperature levels should also be
considered in relation to the humidity of the air. A high
humidity reduces evaporative cooling from the body
and hence creates the sensation of a higher temperature.
Beyond certain limits, however, humidity produces
disagreeable sensations.
For normal comfort conditions, relative humidity (RH)
values between 40 percent and 70 percent are
acceptable.
4.4.3 Inside Design Conditions
The inside design conditions for some of the
applications are indicated in Table 2.
4.4.4 Outside Design Conditions
The outside design conditions (dry-bulb and mean
coincidental wet-bulb) taken shall be in accordance
with the summary of the conditions given in the
Table 3.
Values of ambient dry-bulb and wet-bulb temperatures
against the various annual percentiles represent the
value that is exceeded on average by the indicated
percentage of the total number of hours. The 0.4
percent, 1.0 percent, 2.0 percent values are exceeded
on average 35, 88 and 175 h in a year. The 99.0 percent
and 99.6 percent values are defined in the same way
but are usually reckoned as the values for which the
corresponding weather elements are less than the
design conditions for 88 h and 35 h, respectively.
Mean coincidental values are the average of the
indicated weather element occurring concurrently with
the corresponding design value.
After the calculation of design dry-bulb temperatures,
the programme located the values of corresponding
wet-bulb temperatures from the database for that
particular station, the average of these values were
computed, which were then called mean of coincidental
wet-bulb temperature.
In the same way design wet-bulb temperatures and
coincidental dry-bulb temperatures were evaluated.
Selection: The design values of 0.4 percent, 1 .0 percent
and 2.0 percent annual cumulative frequency
of occurrence may be selected depending upon
application of air conditioning system.
For normal comfort jobs values under 1 percent column
could be used for cooling loads and 99 percent column
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION
17
Table 2 Inside Design Conditions for Some Applications
(Clause 4.4.3)
SI Category
No.
(1)
(2)
Inside Design Conditions
Summer
(3)
Winter
(4)
i) Restaurants
ii) Office buildings
iii) Radio and television studios
iv) Departmental stores
v) Hotel guest rooms
vi) Class rooms
vii) Auditoriums
viii) Recovery rooms
ix) Patient rooms
x) Operation theatres
xi) Museums and libraries
xii) Telephone terminal rooms
DB 23 to 26°C
RH 55 to 60%
DB 23 to 26°C
RH 50 to 60%
DB 23 to 26°C
RH 45 to 55%
DB 23 to 26°C
RH 50 to 60%
DB 23 to 26°C
RH 50 to 60%
DB 23 to 26°C
RH 50 to 60%
DB 23 to 26°C
RH 50 to 60%
DB 24 to 26°C
RH 45 to 55%
DB 24 to 26°C
RH 45 to 55%
DB17to27°C
RH 45 to 55%
DB 20 to 22°C
RH 40 to 55%
DB 22 to 26°C
RH 40 to 50%
DB21to23°C
RH not less than 40%
DB 21 to 23°C
RH not less than 40%
DB 21 to 23°C
RH 40 to 50%
DB 21 to 23°C
RH not less than 40%
DB 23 to 24°C
RH not less than 40%
DB 23 to 24°C
RH not less than 40%
DB 23 to 24°C
RH not less than 40%
Table 3 Summary for Outdoor Conditions
(Clause 4.4.4)
Station
Cooling DB/MCWB
Cooling WB/MCDB
Heating DB/MCWB
0.
DB
,4%
i DB
.0%
MCWB
2.0%
DB MCWB
0.4%
1.0%
* r -\
WB MCDB
2.0%
WB MCDB
99.6%
DB MCWB
99
DB
.0%
MCWB
I WB
MCDB
MCWB
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
. (15)
(16)
(17)
Ahmedabad
42.3
24.1
41.2
23.5
40.0
24.3
28.7
34.3
28.2
33.6
27.8
33.1
11.5
9.0
12.9
9.8
Akola
43.4
24.0
42.2
23.3
41.0
23.6
27.6
37.8
26.7
34.4
26.1
33.5
12.7
10.3
13.9
10.6
Allahabad
43.7
23.4
42.2
23.5
40.8
22.7
28.8
33.0
28.4
32.8
28.0
32.6
7.9
7.0
9.1
8.3
Amritsar
41.6
23.2
40.3
24.6
38.9
24.4
29.3
34.8
28.8
34.8
28.4
33.4
2.7
2.3
4.0
3.5
Aurangabad
40.3
22.1
39.3
22.9
38.3
21.3
26.3
36.2
25.3
33.1
24.7
31.4
10.6
8.2
12.0
9.1
Bangalore
34.7
19.6
34.0
19.6
33.1
19.2
23.5
28.9
22.9
28.2
22.5
27.7
14.9
13.0
15.7
13.8
Banner
43.1
24.2
42.0
23.6
41.0
23.3
28.5
37.9
27.8
35.3
27.2
33.3
9.5
5.1
10.7
5.5
Belgaum
36.5
19.4
35.7
19.6
34.7
19.2
24.3
29.2
23.8
29.5
23.4
28.2
13.2
11.3
14.3
12.2
Bhagalpur
42.4
26.8
40.7
27.4
38.9
25.6
30.0
37.1
29.6
36.4
29.2
35.2
11.4
10.3
12.6
12.4
Bhopal
41.7
22.0
40.5
21.7
39.3
21.3
26.0
31.0
25.6
30.3
25.2
29.9
9.8
6.8
11.0
8.0
Bhubaneshwar
38.9
25.5
37.6
26.6
36.3
26.3
29.4
35.2
28.9
33.3
28.5
32.7
14.4
13.1
15.4
14.0
Bikaner
44.8
22.4
43.4
22.4
42.0
23.1
28.5
34.6
27.9
33.1
27.3
34.7
3.8
2.2
5.3
3.1
Chennai
38.4
26.2
37.3
26.7
36.3
26.4
29.1
33.8
28.6
33.2
28.1
31.9
19.5
20.2
18.7
19.3
Chitradurg
36.6
18.8
35.8
19.0
35.0
19.6
23.9
28.9
23.5
28.2
23.2
28.5
15.4
12.5
16.4
13.3
Dehradun
37.8
23.5
36.3
23.9
34.8
22.8
27.0
31.3
26.5
30.1
26.0
29.8
5.9
5.0
6.8
5.8
Dibrugarh
34.0
27.4
33.2
26.8
32.3
26.7
28.3
32.6
27.8
31.8
27.4
31.3
7.5
7.2
8.7
8.4
Gorakhpur
41.4
26.2
40.3
26.0
39.1
26.4
29.9
35.2
29.7
35.5
29.4
34.7
7.9
7.5
9.0
8.4
Guwahati
34.4
26.9
33.4
27.3
32.7
26.8
28.8
32.4
28.3
31.8
27.9
31.5
10.2
9.8
11.3
10.8
18
NATIONAL BUILDING CODE OF INDIA
Table 3 — Concluded
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
(16)
(17)
Gwalior
43.9
23.0
42.5
22.9
41.3
23.5
27.9
32.9
27.6
32.4
27.3
32.7
4.9
3.8
6.4
5.3
Hissar
44.7
26.5
43.3
25.8
41.7
27.9
30.1
40.2
29.9
39.0
29.4
36.8
5.0
4.2
6.1
5.2
Hyderabad
40.4
22.5
39.2
22.5
38.2
22.4
25.6
33.7
25.2
32.4
24.8
32.0
14.4
12.4
15.5
12.9
Imphal
31.1
23.3
30.2
23.5
29.6
22.9
25.0
29,5
24.6
28.6
24.3
28.3
3.9
3.6
5.0
4.6
Indore
41.1
20.7
40.4
20.6
38.9
21.0
25.7
31.0
25.2
30.0
24.8
29.8
8.2
5.0
9.7
6.5
Jabalpur
42.6
22.7
41.2
23.2
39.8
22.5
26.8
31.8
26.4
32.0
26.0
31.2
7.8
6.7
9.3
7.6
Jagdelpur
39.4
22,3
38.6
22.5
37.4
22.4
26.4
32.4
25.9
31.8
25.4
30.7
8.9
7.9
10.1
8.7
Jaipur
42.8
22.5
41.4
22.6
39.4
22.6
27.4
33.1
27.0
32.1
26.6
31.7
6.4
4.5
8.0
5.8
Jaisalmer
43.7
23.7
42.5
23.1
41.4
23.5
27.7
34.8
27.3
34.5
26.9
34.4
5.0
2.5
6.5
3.7
Jamnagar
37.1
24.4
36.1
25.6
35.3
25.1
29.2
33.0
28.4
32.5
27.9
32.0
10.0
8.6
11.7
10.5
Jodhpur
42.0
23.2
40.8
23.0
39.6
22.7
28.0
35.4
27.4
33.7
26.9
33.8
7.5
4.3
8.7
5.4
Jorhat
34.4
28.2
33.6
27.7
32.9
27.3
28.7
32.7
28.3
32.1
28.0
31.8
9.6
9.0
10.6
10.1
Kolkata
37.2
25.4
36.2
26.1
35.2
26.5
29.5
34.3
29.0
33.4
28.6
32.7
12.0
10.9
13.1
12.9
Kota
43.5
23.0
42.4
22.6
41.2
22.6
27.3
35.2
26.8
33.0
26.5
31.8
9.9
6.7
10.8
7.6
Kurnool
41.6
23.2
40.3
24.6
38.9
24.4
29.3
34,8
28.8
34.8
28.4
33.4
2.7
2.3
4.0
3.5
Lucknow
42.0
24.2
40.8
24.8
39.3
24.5
28.8
33,3
28.4
32.4
28.0
32.2
7.5
6.8
8.4
7.7
Mangalore
33.9
24.4
33.9
24.0
33.4
24.2
27.1
31,0
26.7
31.0
26.*
30.7
19.7
17.0
20.5
18.1
Mumbai
35.3
22.8
34.3
23.3
33.5
24.0
27.9
31,8
27.5
31.3^
27.2
31.1
16.5
13.9
17.8
14.8
Nagpur
43.8
23.6
42.6
23.9
41.4
23.6
27.3
31.2
26.6
33.2
26.2
31.9
11.5
9.4
12.8
10.2
Nellore
40.4
27.8
39.0
28.1
37.8
27.2
30.0
37,1
29.4
35.4
28.8
34.0
19.4
18.3
20.2
19.3
New Delhi
41.8
23.6
40.6
23.8
39.4
23.5
28.4
33.3
28.0
33.3
27.6
32.7
6.0
5.2
7.1
6.3
Panjim
34.0
24.8
33.5
25,2
33.0
25.2
27.7
32.3
27.4
31.5
27.0
30.9
19.6
17.8
20.3
18.7
Patna
40.7
23.4
39.5
23.7
38.0
24.7
29.0
33.9
28.6
33.1
28.3
32.6
8.0
7.6
9.2
8.6
Pune
38.4
20.5
37.4
20.4
36.3
20.6
24.8
30.9
24.4
30.6
24.0
29.6
9.2
8.0
10.3
9.2
Raipur
43.6
23.3
42.2
23.3
40.8
23.0
27.1
31.8
26.8
32.0
26.5
31.2
11.3
9.9
12.6
10.4
Rajkot
40.8
23.1
39.9
23.8
38.9
23.4
28.1
33.9
27.6
33.3
27.1
32.3
10.9
6.5
12.2
7.7
Ramagundam
43.4
25.6
42.2
25.1
40.7
25.8
28.3
37.3
27.9
35.6
27.4
34.4
12.5
11.2
13.7
12.5
Ranchi
38.9
22.1
37.7
21.8
36.4
21.5
26.2
31.7
25.6
30.4
25.2
29.2
9.1
7.2
10.4
8.3
Ratnagiri
34.1
22.4
33.4
23.2
32.8
23.6
27.6
31,1
27.3
30.8
27.0
30.2
18.3
14.9
19.2
16.5
Raxaul
38.6
23.1
36.9
24.5
35.5
24.6
28.9
33.0
28.4
32.0
28.1
31.8
7.5
7.3
8.5
8.2
Saharanpur
41.3
23.8
39.6
24.6
38.1
24.0
28.5
33.6
28.1
32.9
27.8
32.5
1.7
1.5
3,0
2.7
Shillong
24.2
19.7
23.5
19.4
22.8
18.9
20.7
23.3
20.3
22.7
19.9
22.2
-1.0
-1.1
0.1
-0.5
Sholapur
41.1
21.6
40.1
21.6
39.1
21.2
26.6
32.6
25.8
32.1
25.1
31.5
16.3
12.4
17.2
12.5
Sundemagar
36.1
19.1
34.6
19.9
33.1
19.4
25.2
30.1
24.8
29.2
24.4
28
1.8
1.3
2.8
2.2
Surat
38.4
22.7
36.9
23.9
35.7
23.4
28.3
32.4
27.9
31.7
27,6
31.4/
14.8
12.6
16.2
12.5
Tezpur
34.2
27.4
33.3
26.5
32.5
27.1
28.9
32.8
28.4
31.8
28.0
31.4
10.5
10.0
12.4
10.9
Tiruchirapalli
39.6
24.6
38.7
25.1
37.8
24.9
27.7
34.5
27.2
33.7
26.9
33.3 ,
19.3
18.2
20.1
18.7
Thiruvanantha-
33.9
26.0
33.4
26.1
32.9
25.9
27.7
32.4
27.4
31.9
27.0
31.0;
^21.6
20.1
22.2
20.8
puram
Veraval
35.2
23.9
33.8
23.5
32.8
26.6
29.1
32.3
28.7
31.6
28.4
31.1
14.3
1QJ
15,6
12.3
Visakhapatnam
36.4
26.5
35.6
27.3
35.0
27.1
29.2
33.8
28.8
33.0
28.4
32.5
15.4
14.9
16,8
16.2
NOTE — Abbreviations used:
DBT — Dry-bulb temperature
WBT — Wet-bulb temperature
MCDB — Mean coincidental dry-bulb temperature
MCWB — Mean coincidental wet-bulb temperature.
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION 19
for heating loads. For critical applications values under
0.4 percent column could be used for cooling loads
and 99.6 percent column for heating loads.
For critical jobs and high energy consumption
applications, hourly load analysis should be evaluated
using computer programmes.
For industrial and other specific applications, the design
conditions shall be as per user' s requirement.
Adequate movement of air shall always be provided
in an air conditioned enclosure, but velocities in excess
of 0.5 m/s in the zone between floor level and 1.5 m
level shall generally be avoided; in the case of comfort
air conditioning, recommended air velocity is 0.13 m/s
to 0.23 m/s in this zone, except in the vicinity of a
supply or return air grille.
4.4.5 Minimum Outside Fresh Air
The fresh air supply is required to maintain an
acceptably non-odorous atmosphere (by diluting body
odorous and tobacco smoke) and to dilute the carbon
dioxide exhaled. This quantity may be quoted per
person and is related to the occupant density and
activity within the space. Table 4 gives minimum fresh
air supply rates for mechanically ventilated or air
conditioned space. The quantity and distribution of
introduced fresh air should take into account the natural
infiltration of the building.
Table 4 specifies requirements for ventilation air
quantities for 100 percent outdoor air when the outdoor
air quality meets the specifications for acceptable
outdoor air quality. While these quantities are for 100
percent outdoor air, they also set the amount of air
required to dilute contaminants to acceptable levels.
Therefore, it is necessary that at least this amount of
air be delivered to the conditioned space at all times
the building is in use.
The proportion of fresh air introduced into a building
may be varied to achieve economical operation. When
the fresh air can provide a useful cooling effect the
quantity shall be controlled to balance the cooling
demand. However, when the air is too warm or humid
the quantity may be reduced to a minimum to reduce
the cooling load.
For transfer of heat/moisture, air circulation is required
to transfer the heat and humidity generated within the
building. In simple systems the heat generated by the
occupants, lighting, solar heat and heat from electrical
and mechanical equipment may be removed by the
introduction and extraction of large quantities of fresh
air. In more elaborate systems air may be re-circulated
through conditioning equipment to maintain the desired
temperature and humidity. The air circulation rates
are decided in relation to the thermal or moisture
loads and the practical cooling and heating range of
the air.
4.4.6 Air Movement
a) In air conditioned spaces — Air movement
is desirable, as it contributes a feeling of
freshness, although excessive movement
should be avoided as this leads to complaints
of draughts. The speed of an air current
becomes more noticeable as the air temperature
falls, owing to its increased cooling effect.
The design of the air distribution system
therefore has a controlling effect of the
quantity and temperature of the air that may
be introduced into a space. The quantity of
fresh air should not be increased solely to
create air movement; this should be effected
by air re-circulation within the space or by
inducing air movement with the ventilation
air system.
b) In buildings — Air flow within a building
should be controlled to minimize transfer of
fumes and smells, for example from kitchens
to restaurants and the like. This is achieved
by creating air pressure gradients within the
building, by varying the balance between the
fans introducing fresh air and those extracting
the stale air. For example, the pressure should
be reduced in a kitchen below that of the
adjacent restaurant.
Care should be taken, however, to avoid excessive
pressure differences that may cause difficulty in
opening door or cause them to slam. In other cases,
such as computer room, the area may be pressurized
to minimize the introduction of dust from adjacent
areas.
4.4.6.1 Fire and smoke control
Air circulation system may be designed to extract
smoke in event of a fire, to assist in the fire fighting
operation and to introduce fresh air to pressurize escape
routes.
4.4.6.2 Removal of particulate matter from air
Efficient air filtration prevents fouling of the system
and is of special importance in urban areas, where
damage is likely to be caused to decorations and fittings
by discoloration owing to airborne dust particles. In
order to obtain maximum filtration efficiency within
the minimum capital and maintenance expenditure, the
utmost care should be given to the location of the air
intake in relation to the prevailing wind, the position
of chimneys and the relative atmospheric dust
concentration in the environs of the building; the
recommendation for siting of air inlets given in 4.1
20
NATIONAL BUILDING CODE OF INDIA
SI
No.
(1)
Table 4 Outdoor Air Requirements for Ventilation 1 ) of Air Conditioned Areas
and Commercial Facilities
(Clause 4.4.5)
Application
(2)
Estimated Maximum 21 Outdoor Air
Occupancy Requirement
Persons/100 m 2
(3)
I/s/Person (l/s)/m 2
(4)
(5)
Remarks
(6)
i)
ii)
iii)
Commercial dry cleaner
Food and Beverage Service
Dining rooms
Cafeteria, fast food
Bars, cocktail lounges
Kitchen (cooking)
30
20
iv) Public Spaces
Corridors and utilities
Public restrooms, 1/s/wc or urinal
Locker and dressing rooms
15
70
10
100
10
100
15
Hotels, Motels, Resorts, Dormitories
Bedrooms
15
Living rooms
Baths
Lobbies
30
8
Conference rooms
50
10
Assemble rooms
120
8
Dormitory sleeping areas
20
8
Office space
7
10
Reception areas
60
8
Telecommunication centers and
60
10
data entry areas
Conference rooms
50
10
Supplementary smoke removal equipment may be
required.
Make up air for food exhaust may require more
ventilating air. The sum of the outdoor air and
transfer air of acceptable quality from adjacent
spaces shall be sufficient to provide an exhaust
rate of not less than 27.5 m 3 /h.m 2 (7.5 1/s.m 2 ).
Independent of room si2e.
15
1 8 Installed capacity for intermittent use.
See also food and beverage services* merchan-
dising, barber and beauty shops, garages, offices.
Some office equipment may require local exhaust.
25
Elevators
Retail stores, sales floors and
show room floors
Basement and street
30
Upper floors
20
Storage rooms
15
Dressing rooms
Malls and arcades
20
Shipping and receiving
10
Warehouses
5
Smoking lounge
70
30
v) Specialty Shops
Barber Shop
25
8
Beauty Parlour
25
13
Florists
8
8
Clothiers, furniture
Hardware, drugs, fabric
8
8
Supermarkets
8
8
Pet shops
vi) Sports and Amusement
Spectator areas
150
8
Game rooms
70
13
0.25
2.5
5.0
1.50
1.00
0.75
1.00
1.00
0.75
0.25
1.50
5.00
Normally supplied transfer air.
Local mechanical exhaust with no re-circulation
recommended.
Normally supplied by transfer air.
Normally supplied by transfer air, local
mechanical exhaust; exhaust with no re-circulation
recommended.
Ventilation to optimize growth may dictate
requirements.
Ice arenas (playing areas)
}When internal combustion engines are operated
for maintenance of playing surfaces, increased
ventilation rates may be required.
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION
21
Table 4 — Concluded
(D
(2)
(3)
(4)
(5)
(6)
Swimming pools (pool and
deck area)
Playing floors (gymnasium)
Ballrooms and discos
Bowling alleys (seating area)
vii) Theatre
Ticket booths
Lobbies
Auditorium
Stages, studios
viii) Transportation
Waiting rooms
Platforms
Vehicles
ix) Workrooms
Meat processing
10
2.50 Higher values may be required for humidity
control.
30
10
100
13
70
13
60
10
150
10
150
8
70
8
100
8
100
8
150
8
Photo studios
10
8
Darkrooms
10
Pharmacy
20
8
Bank vaults
5
8
Duplicating, printing
x) Education
Classrooms
50
8
Laboratories
30
10
Training shop
30
10
Music rooms
50
8
Libraries
20
8
Locker rooms
Corridors
Auditoriums
150
8
xi) Hospital, Nurses and Convalescent
Homes
Patient rooms
10
13
Medical procedure
20
8
Operating rooms
20
15
Procedure Recovery and ICU
20
Autopsy
Physical therapy
20
8
Correctional Cells
20
10
Dining halls
100
8
Guard stations
40
8
2.50
2.50
Special ventilation will be needed to eliminate
special stage effects (for example, dry ice vapours,
mists, etc).
Ventilation within vehicles may require special
consideration.
Spaces maintained at low temperature at (-10°F to
+ 50°F or -23°C to + 10°C) are not covered by
these requirements unless the occupancy is
continuous. Ventilation from adjoining spaces is
permissible. When the occupancy is intermittent,
infiltration will normally exceed the ventilation
requirement.
Installed equipment shall incorporate positive
exhaust and control (as required) of undesirable
contaminants (toxic and otherwise).
Special contaminant control systems may be
required for processes or functions including
laboratory animal occupancy.
2.50
0.50
Special requirements or codes provisions and
pressure relationships may determine minimum
ventilation rates and filter efficiency.
8 Generating contaminants may require higher
rates.
2.50 Air shall not be recirculated into other spaces.
This table prescribes supply rates of acceptable outdoor air required for acceptable indoor air quality. These values have been chosen
to dilute human bioeffluents and other contaminants with an adequate margin of safety and to account for health variations among
people and varied activity levels.
1 Net occupiable space.
22
NATIONAL BUILDING CODE OF INDIA
should also be taken into account. Air filtration
equipment should be regularly serviced.
Air borne dust and dirt may be generated within the
building, from the interior finishes such as partitions,
laminations, carpets, upholstery, etc, personnel and
their movements as well as by machines such as,
printers and fax machines.
The degree of filtration necessary will depend on the
use of the building or the conditioned space. Certain
specialized equipment, normally associated with
computers, will require higher than normal air filter
efficiencies for satisfactory operation. It is important
to ascertain the necessary standard of air cleanliness
required for equipment of this type.
The choice of filtration systems will depend on the
degree of contamination of the air and on the cleanliness
required. A combination of filter types may well give
the best service and the minimum operating costs.
The normal standard for intake filters in ventilating
and air conditioning applications is an efficiency of
95 percent for a particle size up to 15 um although
there may be a requirement for a higher efficiency to
give increased protection against atmospheric staining.
Special applications, such as computer server rooms,
clean rooms, healthcare, pharmaceutical or food
processing, and air systems having induction units,
require a higher standard that is achieved by two stage
filtration. The exact requirements will depend on the
equipment or process involved.
4.4.6.3 Removal of fumes and smells from air
Fumes and smells may be removed from air by physical
or chemical processes. These may be essential when
ambient air is heavily polluted.
The decision to use odour-removing equipment will
normally be made on economic grounds, this may
become necessary by the currently rising cost of fuel.
Once such equipment is installed, it has to be regularly
serviced to ensure satisfactory performance. Failure
to do this may result in unacceptable conditions within
the building.
4.5 Statutory Regulation and Safety Considerations
4.5.1 Authorities and Approval of Schemes
A ventilation or air conditioning system should comply
with the requirements laid down in the current statutory
legislation or any revisions currently in force and
consideration should also be given to any relevant
insurance company requirements.
4.5.2 Fire and Safety Considerations
Fire protection requirements of air conditioning
systems shall be in accordance with Part 4 Tire and
Life Safety'.
4.5.2.1 Design principles
The design of air conditioning system and mechanical
ventilation shall take into accounfcthe fire risk within
the building, both as regards structural protection and
means of escape in case of fire.
The extent and detail of statutory control and other
specialist interest may vary considerably according to
the design, use, occupation and location of the building,
and the type of system of mechanical ventilation and
air conditioning proposed. It is therefore particularly
important that the appropriate safeguards are fully
considered at the concept design stage of the building.
The degree of control and the requirements vary
according to the application.
Full details may have to be approved by the Authority
in following cases:
a) From the point of view of the means of escape
(except dwelling houses) where recirculation
of air is involved and/or where pressurized
staircases are contemplated as part of the
smoke control arrangements;
b) Places of public entertainment; and
c) Large car parks, hotels, parts of building used
for trades or processes involving a special risk,
and departmental stores and similar shop risks
in large buildings.
4.5.2.2 Ductwork and enclosures
All ductwork including connectors fittings and
plenums should be constructed of steel, aluminium or
other approved metal or from non-combustible
material. All exhaust ducts, the interior of which is
liable in normal use to accumulate dust, grease or other
flammable matter, should be provided with adequate
means of access to facilitate cleaning and inspection.
Also, the concerned provisions of Part 4 Tire and Life
Safety' shall be complied with.
4.5.2.3 Thermal and acoustic insulation
To reduce the spread of fire or smoke by an air
conditioning system, care should be taken for the
choice of materials used for such items as air filters,
silencers and insulation both internal and external {see
Part 4 Tire and Life Safety' and Part 5 'Building
Materials').
4.5.2.4 Fire and smoke detection
When the system involves the recirculation of air,
consideration should be given to the installation of
detection devices that would either shut off the plant
and close dampers or discharge the smoke-laden air to
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION
23
atmosphere. Detectors may be advisable in certain
applications even when the system is not a recirculatory
one. Exhausts should not be positioned near the fire
escapes, main staircases or where these could be a
hindrance to the work of fire authorities. The local fire
authorities should be consulted.
A careful study of the operating characteristics of each
type of sensing device should be made before selection.
Smoke detectors are normally either of the optical or
ionization chamber type. These can be used to either
sound an alarm system or operate a fire dampers. Care
should be taken with their location as various factors
affect the satisfactory operation.
Ionization type detectors are sensitive to high velocity
air streams and if used in ductwork the manufacturer
should be consulted. Activation of smoke detector
should stop the air handling unit supply air fan, close
the fire damper in supply and return air duct and operate
a suitable alarm system.
In all the above instances the appropriate controls
would require manual re-setting.
4.5.2.5 Smoke control
While it is essential that the spread of smoke through
a building to be considered in the design of air
conditioning systems for all types of applications, it
assumes special significance in high rise buildings,
because the time necessary for evacuation may be
greater than the time for the development of untenable
smoke conditions on staircases, in lift shafts and in
other parts of the building far away from the fire. Lifts
may be filled with smoke or unavailable, and, if mass
evacuation is attempted, staircase may be filled with
people.
One or more escape staircase connecting to outdoors
at ground level, should be pressurized, to enable mass
evacuation of high rise buildings (see also Part 4 Tire
and Life Safety').
Therefore all air handling systems of a building should
be designed with fire protection and smoke control
aspects incorporating, where appropriate, facilities to
permit their operation for the control of smoke within
the building in event of fire.
The pressurization systems for staircases use large
volumes of outside air. The system may be designed
to operate continuously at low speed, being increased
to high speed in the event of fire, or to operate only in
emergency. Noise and droughts are not considered a
problem in an emergency situation. Fan motor and
starter should be protected from fire and connected to
the emergency electrical supply through cables with
special fire resistant coating (see also Part 4 Tire and
Life Safety').
4.6 Application Factors
4.6.1 General
This clause gives general guidance, for various
applications, for the factors that usually influence the
selection of the type, design and layout of the air
conditioning or ventilating system to be used.
4.6.1.1 Commercial applications
The primary objective of the application described
under this heading is provision of comfort conditions
for occupants.
4.6.1.2 Offices
Office building may include both external and internal
zones.
The external zone may be considered as extending from
approximately 4 m to 6 m inwards from the external
wall, and is generally subjected to wide load variation
owing to daily and annual changes in outside
temperature and solar radiation. Ideally, the system(s)
selected to serve an external zone should be able to
provide summer cooling and winter heating. During
intermediate seasons the external zone of one side of
the building may require cooling and at same time the
external zone on another side of the building may
require heating. The main factors affecting load are
usually window area and choice of shading devices.
The other important factors are the internal gain owing
to people, light and office equipment. Choice of system
may be affected by requirements to counteract down
draughts and chilling effect due to radiation associated
with single glazing during winter.
Internal zone loads are entirely due to heat gain from
people, lights and office equipment, which represent a
fairly uniform cooling load throughout the year.
Other important considerations in office block
applications may include requirements for individual
controls, partitioning flexibility serving multiple
tenants, and requirement of operating selected areas
outside of normal office hours. Areas such as
conference rooms, board rooms, canteens, etc, will
often require independent systems.
For external building zones with large glass areas, for
example, greater than 60 percent of the external facade,
the air-water type of system, such as induction or fan
coil is generally economical than all air systems and
has lower space requirements. For external zones with
small glass areas, an all air system, such as variable
volume, may be the best selection. For building with
average glass areas, other factors may determine the
choice of system.
For internal zones, a separate all-air system with
volume control may be the best choice. Systems
24
NATIONAL BUILDING CODE OF INDIA
employing reheat or air mixing, while technically
satisfactory, are generally poor as regards energy
conservation.
4.6.1.3 Hotel guest rooms
In ideal circumstances, each guest room in a hotel or
motel should have an air conditioning system that
enables the occupant to select heating or cooling
as required to maintain the room at the desired
temperature. The range of temperature adjustment
should be reasonable but, from the energy conservation
view point, should not permit wasteful overcooling or
overheating.
Guest room systems are required to be available for
operation on a continuous basis. The room may be
unoccupied for most of the day and therefore provision
for operating at reduced capacity, or switching off, is
essential. Low operating noise level, reliability and ease
of maintenance are essential. Treated fresh air
introduced through the system is generally balanced
with the bathroom extract ventilation to promote air
circulation into the bathroom. In tropical climates,
where the humidity is high an all-air system with
individual room reheat (and/or recool) may be
necessary to avoid condensation problems. Fan coil
units are generally found to be most suitable for this
kind of application with speed control for fan and
motorised/modulating valve for chilled water control
for cooling.
4.6.1.4 Restaurants, cafeteria, bars and night-clubs
Such applications have several factors in common;
highly variable loads, with high latent gains (low
sensible heat factor) from occupants and meals, and
high odour concentrations (body, food and tobacco
smoke odours) requiring adequate control of fresh air
extract volumes and direction of air movement for
avoidance of draughts and make up air requirements
for associated kitchens to ensure an uncontaminated
supply.
This type of application is generally best served by
the all-air type of system preferably with some reheat
or return air bypass control to limit relative humidity.
Either self-contained packaged units or split systems,
or air-handling unit served from a central chilled
system may be used. Sufficient control flexibility to
handle adequately the complete range of anticipated
loads is essential.
4.6.1.5 Department stores/shops
For small shops and stores unitary split type air
conditioning systems offer many advantages, including
low initial cost, minimum space requirement and ease
of installation.
For large department stores a very careful analysis of
the location and requirement of individual department
is essential as these may vary widely, for example, for
lighting departments, food halls, restaurants, etc. some
system flexibility to accommodate future changes may
be required.
Generally, internal loads from lighting and people
predominate. Important considerations include initial
and operating costs, system space requirements, ease
of maintenance and type of operating personnel who
will operate the system.
The all-air type of system, with variable volume
distribution from local air handling units, may be the
most economical option. Facilities to take all outside
air for 'free-cooling' under favourable conditions
should be provided.
4.6.1.6 Theatre s/Auditoria
Characteristics of this type of application are buildings
generally large in size, with high ceiling, low external
loads, and high occupancy producing a high latent gain
and having low sensible heat factor. These give rise to
the requirements of large fresh air quantities and low
operating noise levels. Theatres and auditoria may be
in use only a few hours a day.
4.6.1.7 Special applications
4.6.1.7.1 Hospitals/Operating theatres
In many cases proper air conditioning can be a factor
in the therapy of the patient and in some instances part
of the major treatment. For special application areas
of hospitals such as operation theatres, reference may
be made to specialist literature.
The main difference in application compared with other
applications are:
a) Restriction of air movement between various
departments and control of air movement
within certain departments, to reduce the risk
of airborne cross infection;
b) Specific need for the ventilation and filtration
equipment to dilute and/or remove particulate
or gaseous contamination and airborne micro-
organisms;
c) Close tolerances in temperatures and
humidities may be required for various areas;
and
d) The design should allow for accurate control
of environmental conditions.
For (a) and (b) the air movement patterns should
minimize the spread of contaminants as for instance,
in operating departments where the air flow should be
such as to reduce the risk of periphery or floor-level
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION 25
air returning to the patient owing to secondary air
currents whilst the general pressurization pattern
should cause air to flow through the department from
sterile to less sterile rooms in progression. In operating
theatres 100 percent fresh air system is normally
provided and air pressures in various rooms are set by
use of pressure stabilizers. Many types of air
distribution pattern within operation theatres are in use
but generally they conform to high-level supply and
low-level pressure relief or exhaust. There is also need
for a separate scavenging system for exhaled and waste
anaesthetic gases with in theatre suites where general
anaesthetic may be administered.
When zoning air distribution systems to compensate for
building orientation and shape, consideration should be
given to ensure that the mixing of air from different
departments is reduced to a minimum. This can be
accomplished by the use of 100 percent conditioned
fresh air with no re-circulation or, where re-circulation
is employed, by providing separate air handling systems
for different departments based on the relative sensitivity
of each to contamination. A degree of stand-by is
provided by this system so that breakdown will affect
only a limited section of the hospital.
Laboratories and other areas dealing with infectious
diseases or viruses, and sanitary accommodation
adjacent to wards, should be at a negative air pressure
compared to any other area to prevent exfiltration of
any airborne contaminants. In extreme cases any
exhaust to atmosphere from these areas has to pass
through high efficiency sub-micron particulate air
(HEPA) filters.
4,6.1.7.2 Computer rooms
The equipment in computer rooms generates heat and
contains components that are sensitive to sudden
variations of temperature and humidity. These are
sensitive to the deposition of dust. Exposure beyond
the prescribed limits may result in improper operation
or need for shut-down of the equipment. The
temperature and humidity in computer rooms need to
be controlled within reasonably close limits, although
this depends on the equipment involved. The relative
humidity may be controlled within + 5 percent in the
range 40 percent to 60 percent. Manufacturers normally
prescribe specific conditions to be maintained. Typical
conditions are air dry-bulb: 21 ± 1.6°C; relative
humidity 50 ± 5 percent; and filtration 90 percent down
to 10 microns.
A low velocity re-circulation system may be used with
5 percent to 10 percent fresh air make-up which is
allowed to exfiltrate from the room and ensure a
positive pressure to prevent entry of dust and untreated
air. The air distribution should be zoned to minimize
temperature variations owing to fluctuation in heat
load. Overhead air supply through ceiling plenums
utilizing linear diffuser or ventilated ceilings is
eminently suited to computer room application,
permitting high air change rates to be achieved without
undue discomfort to personnel.
The air conditioning system should be reliable because
failure to maintain conditions for even a short duration
can cause substantial monetary loss and possibly more
serious consequence. As such standby equipment is
recommended,
4.6.1.8 Residential buildings
Very few residences are air conditioned. Some
individual houses have unitary systems comprising of
window/split air conditioners. Some large houses have
VRV based splits and some luxury block of flats are
provided with air-water systems. VAV also works well
for some luxury applications with chilled water
applications. In the latter case, most of the considerations
of 4.6.1.3 apply.
5 NOISE AND VIBRATION CONTROL
5.1 General
Noise is unwanted sound. All ventilating and air
conditioning systems will produce noise, and this may
cause annoyance or disturbance in:
a) the spaces being treated;
b) other rooms in the building;
c) the environment external to the building.
In the case of external environment particular care
should be taken to avoid a nuisance in the 'silent* hours,
and local authorities have statutory powers to ensure
that noise from plant is Umited.
It is important that expert advice be sought in dealing
with noise and vibration problems, as for obvious
reasons the most economical solutions should be used,
without impairing the performance.
5.2 Types of Noise in Building
5.2.1 Externally Created Noise
Reduction of externally created noise is mainly dealt
with by choice of building profile and window
construction. The air conditioning designer should,
however, ensure that noise does not enter via air inlets
or exhausts: it may be reduced by suitable attenuators.
5.2.2 Generated Noise
Noise produced by the components of air conditioning
and ventilation plant installed within the building can
escape via ventilation grilles or door openings and can
cause nuisance to neighbours. Equipment mounted
26
NATIONAL BUILDING CODE OF INDIA
outside the building may well need to be selected or
installed with the noise problem in mind.
Another type of generated noise is created by the air-
circulating system itself and its associated equipment.
Fans are an obvious source, but noise can be produced
by turbulence, which may cause vibration of the ducts
and noise transmission by air diffusers. This problem
can be avoided by careful selection of and installation
equipment or by the noise absorbing devices.
5.2.3 Transmitted Noise
Noise transmitted through the building structure is
particularly acute in modern frame and reinforced
concrete buildings. Such noise can be controlled by
isolating the machines from the structures, and from
pipe work connected to the building, by suitable
mountings and pipe couplings.
Another problem is the transmission of sound from
one room to another via air ducting, ventilated ceilings
or other continuous air space. Such sound includes the
noise from machines and equipment and also
of conversation, transmission of which can be
embarrassing as well as annoying. Again, this problem
can be tackled by careful design and the inclusion of
sound absorbing devices in ducts.
5.2.4 Intermittent Noise
Such noise arises from the stopping and starting of
equipment, and the opening and closing of valves and
dampers. This may or may not cause problems in the
air conditioned spaces, but it is often objectionable to
plant operators and maintenance engineers. This should
be considered by air conditioning designer.
5.3 The source of noise in the air conditioning system
could be from the following:
a) Chillers,
b) Pumps,
c) Pipe supports,
d) Ducts,
e) External noise in Alteration though openings,
f) Fans,
g) Air noise through ducts, and
h) Compressors.
5.4 The approach must always be to reduce the source
noise rather than controlling them in the path
5.5 Noise Control
5.5.1 From Room Air Conditioners (RAC)
The following measures should be adopted:
a) Selection of RAC which has the least noise
at various fan speeds.
b) Install it at a serviceable height.
c) Install preferably in a wall or on a rigid
window.
d) Provide only necessary slope as specified by
the manufacturer, to avoid any unusual noise
from the compressor because of tilting.
e) Install it preferably in the middle portion of
the wall/window to avoid additional directivity
(do not install at the end of a wall.
f) Ensure all leaks are sealed properly.
g) Avoid condenser facing any high noisy areas,
such as road/factory to avoid any such noise
predominantly entering into the room.
h) Do not provide any props at the back side
bottom of the air conditioner unless specified
by the manufacturer,
j) Prepare the opening to suit the chassis with
wooden frame of adequate rigidity and
thickness.
5.5.2 From Split Air Conditioner/Furred Inn
The following measures should be adopted:
a) Install the evaporator only on a rigid wall/
ceiling or on a pedestal.
b) Avoid installation over wooden/gypsum
board partition. Should a need arise anchor
the evaporator rigidly by using mild steel
frame work from the roof to avoid vibration.
c) Provide proper V trap in the condensate
water line to ensure a good water seal, which
will also avoid sound penetration into the
room from outside.
d) If the capillary is in the evaporator, ensure
that flow noise is avoided.
e) Ensure proper return air entry back to the coil,
since blowers working at higher static
pressure will create higher noise.
f) Select the condensers with top/side discharge
depending upon location to avoid nuisance
to neighbours.
g) Place condensers on rigid platform, properly
supported propped and fixed firmly.
h) Ensure all screws, bolts and nuts are firmly
tightened since stiffening is more advantageous
in higher frequencies for vibration reduction.
5.5.3 Air Handling Units (Floor Mounted and Ceiling
Suspended)
The following measures should be adopted:
a) Selected indoor machine for specific air
quantity and static pressure.
b) Suspend the indoor machine and ducts
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION 27
without touching the members of the false
ceiling or partitions.
c) Ensure that ducts/duct supports do not touch
the evaporator.
5.5.4 From Plenum Chamber
The following measures should be adopted/considered:
a) If possible and if pressures allow, expand the
air to a plenum chamber (of 2.5 m/s for
normal office), which is acoustically lined
inside.
b) Stiffening of the plenum body is very critical
since it could create a drumming noise.
c) Plenum chambers with sound absorbing
material are frequently used as silencers in
air conditioning and ventilating systems and
in testing facilities to reduce flow velocity and
turbulence. The attenuation of these devices
may be due to both dissipative and reactive
effects.
5.5.5 From Fans
5.5.5.1 Centrifugal fans
There are three basic types of centrifugal fans,
backward curved, forward curved, and radial. Noise
from centrifugal fans is dominantly a superimposition
of discrete tones at the varying frequencies and
broadband aerodynamic noise.
5.5.5.2 Axial fans
Axial fans derive their name from the fact that the
airflow is along the axis of the fan. To avoid a circular
flow pattern and to increase performance, guide vanes
are usually installed downstream of the rotor. Axial
fans with exit guide vanes are called vane axial and
those without guide vanes are called tube axial. Axial
fans generally operate at higher pressures than
centrifugal fans and are usually considered noisier.
Common applications include heating and ventilation
systems. Because of the large number of blades and
high rotational speeds, noise from axial fans is
generally characterized by strong discrete blade
passing tones.
Variable inlet vane system may generate significantly
low frequency noise as the vanes shut down. Additional
attenuation with a corresponding additional pressure
drop is required to attenuate the noise generated by
the inlet vanes.
Variable speed motors and drives and variable pitch
fan blade systems are actually quieter at reduced air
output than at full output. The designer has the option
of designing for maximum output as if the system were
constant volume, or selecting the sound attenuation
for a more normal operating point and allowing fan
noise to exceed the design criteria on the rare occasions
when the fan operates at full output.
5.5.5.3 To reduce fan noise, the following should be
adopted:
a) Design the air distribution system for
minimum resistance, since the sound generated
by a fan, regardless of type, increase by the
square of the static pressure. Turbulence can
increase the flow noise generated by duct
fittings and dampers in the air distribution
systems especially at low frequencies.
b) Examine the specific sound power levels of
the fan designs for any given job. Different
fans generate different levels of sound and
produce different octave band spectra. Select
a fan that will generate the lowest possible
sound level, commensurate with other fan
selection parameters.
c) Fans with relatively few blades (less than 15)
tend to generate tones, which may dominate
the spectrum. These tones occur at the blade
passage frequency and its harmonies. The
intensity of these tones depends on resonance
with the duct system, fan design, and inlet
flow distortions.
d) Select a fan to operate as near as possible to its
rated peak efficiency when handling the
required quantity of air and static pressure.
Also, select a fan that generates the lowest
possible noise but still meets the required
design conditions for which it is selected. Using
an oversized or undersized fan, that does not
operate at or near rated peak efficiency, may
result in substantially higher noise levels.
e) Design duct connections at both the fan inlet
and outlet for uniform and straight airflow.
Avoid unstable, gusting, and swirling inlet
airflow. Deviation from accepted applications
can severely degrade both the aerodynamic
and acoustic performance of any fan and
invalidate manufacturers ratings or other
performance predictions.
f) Select duct silencers that do not significantly
increase the required fan total static pressure.
5.5.6 From Chillers, Pumps and Pipes
Sizing and selecting a chiller is an important aspect in
noise control. The following guidelines may be
considered for noise control:
a) For roof top installation of chillers, these may
be placed on beams connected on the elevated
levels of pillars on correctly chosen vibration
isolators.
28
NATIONAL BUILDING CODE OF INDIA
b) Water cooled chillers have less vibration.
However, if air cooled chillers have to be
chosen, choose them with fan of less speeds
and compressors must be jacketed without
compromising their ventilation requirement.
c) If much more silencing is required, plan a
silencer on the exhaust of the fans and also
an acoustic enclosure around the chillers. Care
must be taken for the additional static demand
in the fan.
5.5.7 From Ducting Work
The following measures should be adopted;
a) Shorter ducts with flanges and bracings is very
advantageous for noise reduction.
b) Choose the right thickness of sheets for
ducting.
c) Provide calculated turning vanes in all bends.
d) Provide take off pieces in all branches and
collars.
e) Minimize the number of terminals since each
terminal of equal noise will create a higher
overall noise inside the room — Two equal
noise source increase the noise by 3 dB.
f) Velocities of supply and return ducts and also
terminals are important for noise control.
g) For auditoriums, conference halls etc, choose
the right silencers in the supply. Define a
clear opening for return air and fix return
air silencers (parallel baffle silencer).
The pressure drop expected across these
silencers varies from 6 mm to 10 mm of water
column.
h) Selecting double skin air handling unit should
be done with care. If used without supply and
return air silencers it adds to the noise in the
duct patch. However, by using double skin
air handling unit the noise inside the plant
room can be lowered.
j) Instead of insulating the plant room, increasing
the density of the plant room wall and
providing return air baffles in the return air
patch is more helpful in noise reduction. The
doors to the air handling unit room should be
either with an attic entry or dense enough to
avoid noise transmission.
k) Avoid terminal dampers and grilles if the
noise criteria is of the order of NC 20
(recording studios).
m) If ducts have to be routed outside the
conditioned space, the density of the
insulating materials over the duct surface is
very critical. Higher the density, lower is its
noise transmitality and hence break in noise
inside the duct can be avoided. The density is
to be decided based on the outside noise level.
n) Selection of a proper terminal device helps
in noise reduction.
p) VAV shall be planned along with relevant
VFD or bypass arrangement. Otherwise the
duct is subjected to variable pressures
resulting in variable noise pattern.
q) Minimize flow-generated noise by elbows or
duct branch takeoffs, whenever possible, by
locating them at least four to five duct
diameters from each other. For high velocity
systems, it may be necessary to increase this
distance to up to ten duct diameters in critical
noise areas.
r) Keep airflow velocity in the duct as low as
possible (7.5 m/s or less) near critical noise
areas by expanding the duct cross-section
area. However, do not exceed an included
expansion angle of greater than 15°. Flow
separation, resulting from expansion angles
greater than 15°, may produce rumble noise.
Expanding the duct cross-section area reduces
potential flow noise associated with turbulence
in these areas.
s) Use turning vanes in large 90° rectangular
elbows and branch takeoffs. This provides a
smoother transmission in which the air can
change flow direction, thus reducing turbulence.
t) Place grilles, diffusers and registers into
occupied space as far as possible from elbows
and branch takeoffs.
u) Minimize the use of volume dampers near
grilles, diffusers and registers in acoustically
critical situations.
v) Vibration isolate ducts and pipes, using spring
and/or neoprene hangers for atleast the first
15 m from the vibration-isolated equipment.
5.6 Structure Borne Noise
Most obvious paths for solid-borne noise are the
attached piping and pump support systems. Oscillatory
energy generated near the pump can be conducted as
solid-borne noise for substantial distances before it is
radiated as acoustic noise. It can be controlled using
flexible couplings and mechanical isolation.
5.7 Measurement
Measurements should be taken with a sound level meter
either using the 'A' weighting scale or to draw up a
noise criteria curve {see Part 8 'Building Services,
Section 4 Acoustics, Sound Insulation and Noise
Control'). Measurements should be taken in the
following locations:
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION
29
a) Plant rooms;
b) Occupied rooms adjacent to plant rooms;
c) Outside plant rooms facing air intakes and
exhausts and condenser discharge, to assess
possible nuisance to adjacent occupied areas;
d) In the space served by the first grille or
diffuser after a fan outlet; and
e) In at least two of the spaces served by fan
coil units or high velocity system terminal
units (where applicable).
6 MECHANICAL VENTILATION (FOR NON AIR
CONDITIONED AREAS) AND EVAPORATIVE
COOLING
6.1 Ventilation
Ventilation is the process of changing air in an enclosed
space. A proportion of the air in the space should be
continuously withdrawn and replaced by fresh air
drawn from outside to maintain the required level of
air purity. Ventilation is required to control the
following:
a) Oxygen Content — Prevent depletion of the
oxygen content of the air;
b) Carbondioxide and Moisture — To prevent
undue accumulation;
c) Contaminants — To prevent undue rise in
concentration of body odours and other
contaminants such as tobacoo smoke;
d) Bacteria — To oxidize colonies of bacteria
and fungas to prevent their proliferation.
e) Heat — To remove body heat and heat
dissipated by electrical or mechanical
equipment or solar heat gains.
Mechanical ventilation is one of several forms of
ventilation options available. It usually consists of fans,
filters, ducts, air diffusers and outlets for air distribution
within the building. It may include either mechanical
exhaust system or exhaust can occur through natural
means.
Natural ventilation and natural exhaust are also options
{see Part 8 'Building Services, Section 1 Lighting and
Ventilation'). The scope of this section is therefore
restricted to mechanical ventilation.
Ventilation controls heat, odours and hazardous
chemical contaminants (in a building) that could affect
the health and safety of the occupants. For better
control, heat and contaminants, air may need to be
exhausted at their sources by local exhaust systems.
Usually such systems require lower air flows than
general (dilution) ventilation.
Following considerations provide details regarding the
various parameters that affect the type of ventilation
system selected for a particular application, and the
sizing of the ventilation plant:
a) The climatic zone in which the building is
located is a major consideration. An important
distinction that must be made is between hot-
dry and warm-moist conditions. Hot-dry work
situations occur around furnaces, forges,
metal-extruding and rolling mills, glass-
forming machines, and so forth.
Typical warm-moist operations are found in
textile mills, laundries, dye houses, and deep
mines where water is used extensively for dust
control.
Warm-moist conditions are more hazardous
than the hot-dry conditions.
b) Siting (and orientation) of the building is also
an important factor. Solar heat gain and
high outside temperature increase the load
significantly; how significantly depends, on
the magnitude of these gains particularly in
relation to other gains for example the internal
load.
c) The comfort level required is another
consideration. In many cases, comfort levels
(as understood in the context of Residential
Buildings, Commercial Blocks, Office
Establishments) cannot be achieved at all and
therefore, what is often aimed at will be
'acceptable working conditions' rather than
'comfort' .
Having surveyed the considerations above,
there are many options available in mechanical
ventilation — spot cooling, local exhaust,
changes in work pattern — to choose from,
for achieving the desired acceptable working
conditions. The options available may need
to be extended to evaporative cooling in
order to achieve more acceptable working
conditions when confronted with more hostile
environmental conditions .
It will be thus seen that there are many
considerations involved in the selection and
sizing of suitable ventilation and evaporative
cooling plants to meet the requirements of any
particular building and/or process. It is the
interplay of these various factors listed above
like climatic conditions, internal load,
exposure to heat and hazardous substances
and level of working conditions aimed at, that
determines the option, which best meets the
requirement and also, the capacity and other
attributes of the option selected.
Ventilation control measures alone are
30
NATIONAL BUILDING CODE OF INDIA
frequently inadequate for meeting heat stress
standards. Optimum solutions may involve
additional controls, such as local exhausts,
spot cooling, changes in work-rest patterns,
and radiation shielding.
As a rule, it is the mechanical system that
provides the best results and controls, for
the more complex situations and more
stringent requirements arising out of harsher
environment and need for better working
conditions.
6.2 Beneficial Effects of Ventilation
6.2.1 Fresh Air Supply
Ventilation system provides the fresh air flow that is
required to maintain an acceptable non-odorous
atmosphere (by diluting body odours and tobacco
smoke) and to dilute the carbon dioxide exhaled.
The quantity and distribution of introduced outside air
takes into account infiltration, exhaust and dilution
requirements of the building. Proportion of fresh air
introduced into a building may be varied to achieve
economical operation. When fresh air can provide
useful cooling effect, the quantity should be controlled
to match the cooling demand.
6.2.2 Transfer of Heat/Moisture
Ventilation system helps air circulation that is required
to transfer the heat and humidity generated within the
building. Heat generated by the occupants, electrical
and mechanical equipment, and solar heat gains may
be removed by the introduction of adequate quantities
of fresh air and by expelling or extracting of stale air.
6.2.3 Air Movement
Ventilation system provides air movement that is
necessary to create a feeling of freshness and avoid
discomfort, although excessive movement should be
avoided as this may lead to complaints of draughts.
The quantity of fresh air should not be increased solely
to create air movement; this should be effected by air
recirculation within the space or by inducing air
movement with the ventilation air system.
Air flow should be controlled to minimize transfer of
fumes and smells. In addition, air pressure gradients may
be created within the building, by varying the balance
between the fresh air and extracting the stale air.
Care should be taken, however, to avoid excessive
pressure differences that can cause difficulty in opening
doors or cause them to slam.
6.2.4 Air Purity and Filteration
Ventilation system installed in a building should deliver
clean, fresh air to the space served. This may be
achieved by providing the required amount of fresh
air either to remove totally or to dilute odours, fumes,
etc. Local extract systems may be necessary to remove
polluted air from kitchens, toilets, slaughter houses,
crematoria, etc. Special air filters may be provided to
remove contaminants or smells when air is recirculated.
6.2.5 Removal of Particulate Matter from Air
Efficient air filteration to prevent fouling of the system
should be considered, where damage is likely to be
caused by discolouration owing to airborne dust
particles. In order to obtain the best performance from
the filters provided, care should be taken to locate the
air intake appropriately in relation to the prevailing
wind, position of chimneys and relative atmospheric
dust concentration in the environs of the building.
This will promote cleaner interiors and reduce dust
loading of the filters. Adequate (space) provisions
should be incorporated in plant layout to ensure that
filters can be serviced regularly.
6.2.6 Fire and Smoke Control
Ventilation system can be designed to extract smoke
in the event of a fire, to assist in the fire fighting
operations and to introduce fresh air to pressurize
escape routes.
6.2.7 Removal of Fumes and Smells from Air
Fumes and smell may be removed from air by physical
or chemical processes. Their removal may be essential
when the ambient air is heavily polluted, although
consideration must be given to limit the thermal loads
caused by the introduction of large quantities of fresh air.
6.3 Industrial Ventilation
Industrial buildings form a major application of
mechanical ventilation.
In industrial buildings, ventilation is needed to provide
the fresh air normally required for health and hygiene
and also, to mitigate thermal working conditions by
assisting in removal of surplus heat due to equipment,
people and building heat gains.
Following are some of ttte factors that should be
considered in the system design:
a) A supply system would not be satisfactory
without a complementary exhaust system.
Similarly any exhaust system would require
for complementary supply system.
b) Air should be supplied equitably through
grilles, diffusers — and such other devices.
Directional grilles, diffusers and nozzles
designed specifically to alleviate the thermal
conditions should be considered. Drafts
should be avoided.
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION
31
c) Ventilation systems may need to be
supplemented by exhaust hoods and canopies
designed to capture the unwanted fumes or
dust right at the source irrespective of other
air currents in the vicinity.
Many industrial ventilation systems shall handle
simultaneous exposures to heat, toxic and hazardous
substances. The number of contaminant sources, their
generation rate and effectiveness of exhaust hoods are
rarely known; there is no option but to depend on
common ventilation/industrial hygiene practice in such
situations.
Reference may also be made to good practice [8-3(4)].
6.4 Types of Ventilation Systems
In the interest of efficient use of energy and comfort
to the occupants, it is imperative that all modes of
ventilation should be considered in relation to the
thermal characteristics of the building.
6.4.1 Mechanical Extract/Natural Supply
This is simplest form of extract system comprising one
or more fans, usually of the propeller, axial flow or
mixed flow type, installed in outside walls or on the
roof. The discharge should terminate in louvers or
cowls or a combination of both.
Alternatively, the system may comprise of ductwork
arranged for general extraction of the vitiated air or
for extraction from localized sources of heat, moisture,
odours, fumes and dust. Such duct work may be
connected to centrifugal or axial flow fans that
discharge through the wall or roof, terminating in
louvers or cowls or a combination of both.
It is essential that provision for make-up air is made
and that consideration is given to the location and size
of inlet. Inlet should not be located in the vicinity of
exhaust fan.
6.4.2 Mechanical Supply/Natural Extract
This system is similar in form to the extract system
but arranged to deliver fresh air positively into the
enclosed space. Such a system necessitates provision
for the discharge of vitiated air by natural means.
Where there is a requirement for the enclosed space to
be at a slightly higher pressure than its surroundings
(to exclude dust or smoke, for example), the discharge
may be through natural leakage paths or balanced
pressure relief dampers, as may be required.
6.4.3 Combined Mechanical Supply and Extract
This system is a combination of those described above
and may comprise supply and exhaust ductwork
systems or may employ a common fan with a fresh air
inlet on the low pressure side.
6.5 Ventilation Rate and Design Coniderations for
Non Air Conditioned Areas
6.5.1 General Ventilation
The rate of air circulation recommended for different
general areas is as given in Table 5.
Table 5 Recommended Rate of Air Circulation
for Different Areas
(Clause 6.5.1)
SI
Application
Air Change
No.
per Hour
(1)
(2)
(3)
1.
Assembly rooms
4-8
2.
Bakeries
20-30
3.
Banks/building societies
4-8
4.
Bathrooms
6-10
5.
Bedrooms
2-4
6.
Billiard rooms
6-8
7.
Boiler rooms
15-30
8.
Cafes and coffee bars
10-12
9.
Canteens
8-12
10.
Cellars
3-10
11.
Churches
1-3
12.
Cinemas and theatres
10-15
13.
Club rooms
12, Min
14.
Compressor rooms
10-12
15.
Conference rooms
8-12
16.
Dairies
8-12
17.
Dance halls
12, Min
18.
Dye works
20-30
19.
Electroplating shops
10-12
20.
Engine rooms
15-30
21.
Entrance halls
3-5
22.
Factories and work shops
8-10
23.
Foundries
15-30
24.
Garages
6-8
25.
Glass houses
25-60
26.
Gymnasium
6, Min
27.
Hair dressing saloon
10-15
28.
Hospitals-sterlising
15-25
29.
Hospital-wards
6-8
30.
Hospital domestic
15-20
31.
Laboratories
6-15
32.
Launderettes
10-15
33.
Laundries
10-30
34.
Lavatories
6-15
35.
Lecture theatres
5-8
36.
Libraries
3-5
37.
Living rooms
3-6
38.
Mushroom houses
6-10
39.
Offices
6-10
40.
Paint shops (not cellulose)
10-20
41.
Photo and X-ray darkroom
10-15
42.
Public house bars
12, Min
43.
Recording control rooms
15-25
44.
Recording studios
10-12
45.
Restaurants
8-12
46.
Schoolrooms
5-7
47.
Shops and supermarkets
8-15
48.
Shower baths
15-20
49.
Stores and warehouses
3-6
50.
Squash courts
4, Min
51.
Swimming baths
10-15
52.
Toilets
6-10
53.
Utility rooms
15-20
54.
Welding shops
15-30
NOTE — The ventilation rates i
may be increased by 50 percent
where heavy smoking occurs oi
• if the room is below ground.
32
NATIONAL BUILDING CODE OF INDIA
6.5.2 Kitchen (Industrial and Commercial) Ventilation
Desired ventilation rates in the kitchens depend upon
the type of equipment in use and the released impurity
loads (including surplus heat). Ventilation Standards
set up the guide lines for ventilation volumes, whereas
surplus heat and impurity loads determine the actual
airflows based on thermal considerations. The design
for kitchen airflow must allow for sufficient ventilation.
Suggested design standards for exhaust airflows from
different kitchen equipment based on their input power
are as given in Table 6.
Table 6 Design Exhaust Air Flow in 1/s per kW
of the Kitchen Equipment
{Clause 6.5.2)
SI
Kitchen Equipment
Electricity
Gas based
No.
based
Equipment
Equipment
0)
(2)
(3)
(4)
i)
Cooking pot
8
12
ii)
Pressure cooker cabinet
5
—
iii)
Convection oven
10
—
iv)
Roasting oven (salamander)
33
33
v)
Griddle
32
35
vi)
Frying pan
32
35
vii)
Deep fat fryer
28
—
viii)
Cooker/stove
32
35
ix)
Grill
50
61
x)
Heated table/bath
30
xi)
Coffee maker
3
xii)
Dish washer
17
__
xiii)
Refrigeration equipment
60
—
xiv)
Ceramic cooker/stove
25
—
xv)
Microwave oven
3
—
xvi)
Pizza oven
15
—
xvii)
Induction cooker/stove
20
—
It is desirable to use compensating exhaust hoods for
kitchen equipment installed within air conditioned
spaces. The ventilation rates may be confirmed from
the kitchen equipment supplier.
6.5.3 Car Parking Ventilation
Ventilation is essential, in car parking areas to take
care of pollution due to emission of carbon monoxide,
oxides of nitrogen, presence of oil and petrol fumes
and diesel engine smoke. These contaminants cause
undesirable effect like nausea, headache, fire hazards,
if applicable permissible limits for each of the
contaminants noted are exceeded. Although four
contaminants are listed above, the capacity of a system
designed to tackle concentration of carbon monoxide,
will be adequate to keep the other three contaminants
also within their respective permissible limits.
The recommended ventilation rate will ensure that the
CO level will be maintained within 29 mg/m 3 with peak
levels not to exceed 137 mg/m 3 .
For partially open garages, the requirement is stated in
terms of area of wall/slab openings required to provide
adequate ventilation. The value applicable is 2.5
percent to 5 percent of the floor area for free opening.
It is necessary to ensure at planning stage itself that
adequate head room is available in the car parks for
installing ventilation ducts if such ducting is involved.
6.5.4 Sizing the Plant
Sizing the ventilation plant is essentially arriving at the
air flow rate required. Based on various considerations
already reviewed the sizing of the plant will be
influenced by the following requirements:
a) Removal of sensible heat,
b) Removal of latent heat,
c) Make-up air — the flow rate required will
depend upon local exhaust, and
d) Removal or dilution of the contaminants
down to the permissible level.
The air flow rate arrived at will be the maximum of
the flow rates calculated for the above requirements.
6.5.4.1 Ventilation plant size is often expressed in
terms of number of air changes per hour or cmh/m 2 of
floor area. These expressions fail to evaluate the actual
heat release provided by the plant. The unit, cmh/m 2
gives a relationship which is independent of the
building height. This is a more rational approach than
speaking in terms of air changes per hour. This is
because, with the same internal load, the same amount
of ventilation air, properly applied to the work zone
with adequate velocity, will provide the desired heat
relief quite independently of the ceiling height of the
space, with few exceptions. Ventilation rates of 30 to
60 m 3 /h per m 2 have been found to give good results
in many plants. Notwithstanding these general
observations, detailed design should be based on
detailed thorough calculations after all necessary data
has been evaluated and relevant considerations have
been reviewed.
6.6 Evaporative Cooling
6.6.1 Evaporative cooling is defined as the reduction
of air dry-bulb temperature by the evaporation of
water.
6.6.2 When water evaporates into the air to be cooled,
simultaneously humidifying it, the process is called
direct evaporative cooling. When the air to be cooled
is kept separate from evaporation process, and therefore
is not humidified as it is cooled, then the process is
called indirect evaporative cooling.
It is good practice to use 100 percent fresh air in
the evaporative cooling. Re-circulation is not
recommended, as it will lead to continuous increase in
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION 33
wet-bulb temperature of the air. When evaporative
cooling is provided for comfort application, it may be
supplemented by devices like ceiling fans and fan
coolers to enhance air movement for circulation of air
in internal areas in order to maximize evaporation of
moisture from the skin.
6.6.3 The geographic range for the evaporative cooling
is based on cooler's ability to create or approximate
human comfort and is limited by relative humidity in
the atmosphere. It is more effective in dry climates
(hot-dry climate zone) where wet-bulb depression is
comparatively large. Factors to be considered —
include those listed in 6.5.4; In addition the following
also apply:
a) Saturation efficiency of the cooler — higher
the better;
b) Ambient weather design data;
c) Permissible temperature rise; and
d) Type of cooling application — residential,
industrial, etc.
6.6.4 The cooling load control, especially for industrial
application shall be carried out in the following manner
for effective evaporative cooling:
a) Minimize external heat loads by shading, use
of heat reflective paints, roof insulation and
sealing of gaps.
b) Minimize internal heat loads by shielding, use
of reflective paints, insulation and installation
of exhaust fans over the hot processes and
machines.
c) Make building tight.
d) Wherever possible, exhaust of used washed
air must be directed towards roof to partly
cool the surface and trusses thereby reducing
heat radiation.
6.6.5 Two types of water distribution systems may be
provided:
a) Once through or pump-less type.
b) Recirculating or pump type.
The first type is simpler and cheaper but consumes
more water, needs constant drainage and has lower
efficiency depending upon the temperature of water.
The second type has higher cooling efficiency due to
recirculate water approaching wet-bulb temperature
conserves water and can operate with intermittent
drainage. It is recommended to provide periodic bleed-
off or blow down to remove accumulated mineral
additions. This helps in reducing scaling of pads also.
6.6.6 The air velocity across wetting pad is
recommended between 1 .0 and 1 .5 m/s. The lower face
velocity reduces evaporation as damp air film isolates
the dry air from the wet surface, Higher face velocity
may provide insufficient air-water contact time.
6.6.7 Pad material should be such which provides
maximum clean wet surface area with minimum
airflow resistance. Materials, which have either good
'wick' characteristics or surface that spread water
rapidly by capillary action, should be selected.
6.6.8 In the ducted systems, all supply air diffusers,
grilles and registers should be preferably adjustable.
6.6.9 General room cooling should be supplemented
with spot cooling in the hot workplaces.
6.6.10 Reference may also be made to good practice
[8-3(5)].
6.7 Planning
6.7.1 Planning of Equipment Room for Ventilation
6.7.1.1 In selecting the location of equipment room,
aspects of efficiency, economy and good practice
should be considered and wherever possible, it shall
be made contiguous with the building. This room shall
be located as centrally as possible with respect to the
area served and shall be free from obstructing columns.
Proper location helps achieve satisfactory air
distribution and also results in a less expensive
installation.
6.7.1.2 Equipment room should preferably be located
adjacent to external wall to facilitate equipment
movement and ventilation. It should also close to main
electrical panel of the building, if possible, in order to
avoid large cable lengths.
6.7.1.3 Location and dimensions of shafts, for ducting,
cables, pipes, etc (if envisaged), should be planned at
the virtual stages itself if planning. They should be
located adjacent to the equipment or within the room
itself.
Evaporative cooling units (air washers) should be
located preferably on summer-windward side. They
should be painted whhe or with reflective coating or
thermally insulated, so as to minimize solar heat
absorption. >
In locating the units, care should be taken to ensure
that their noise level will not be objectionable to the
neighbours. Appropriate acoustic treatment should be
considered, if the noise levels cannot be kept down to
permissible limits.
Exhaust air devices, preferably to leeward and
overhead side may be provided for effective movement
of air.
In the case of large installations it is advisable to have
a separate isolated equipment room if possible.
34
NATIONAL BUILDING CODE OF INDIA
The equipment room should be adequately dimensioned
keeping in view the need to provide required movement
space for personnel, space for entry and exit of ducts,
the need to accommodate air intakes and discharge,
operation, maintenance and service requirements.
6.7.1.4 The floors of the equipment rooms should be
light coloured and finished smooth. For floor loading,
the air conditioning, heating and ventilation engineer
should be consulted (see also Part 6 'Structural Design,
Section 1 Loads, Forces and Effects').
Arrangements for draining the floors shall be provided.
The trap in floor drain shall provide a water seal
between the equipment room and the drain line. Water
proofing shall be provided for floor slabs of equipment
rooms housing, evaporative cooling units.
6.7.1.5 Supporting of pipe within equipment rooms
spaces should be normally from the floor. However,
outside Equipment room areas, structural provisions
shall be made for supporting the water pipes from the
floor/ceiling slabs. All floor and ceiling supports make-
up and drain connections pipes, ducting cables/cable
trays etc, shall be isolated from the structure to prevent
transmission of vibrations.
6.7.1.6 Plant machinery in the plant room shall be
placed on plain/reinforced cement concrete foundation
and provided with anti-vibratory supports. All
foundations should be protected from damage by
providing epoxy coated angle nosing. Seismic
restraints requirement may also be considered.
6.7.1.7 Wherever necessary, acoustic treatment should
be provided in plant room space to prevent noise
transmission to adjacent occupied areas.
6.7.1.8 In case the equipment is located in basement,
equipment movement route shall be planned to
facilitate future replacement and maintenance. Service
ramps or hatch in ground floor slab should be provided
in such cases. Also arrangements for floor draining
should be provided.
The trap in floor drain shall provide a water seal
between the equipment room and the drain line.
6.7.1.9 In the case of large and multi-storied buildings,
independent Ventilation/ Air Washer Units should be
provided for each floor. The area to be served by the
air-handling unit should be decided depending upon
the provision of fire protection measures adopted. The
Units should preferably be located vertically one above
the other to simplify location of pipe shafts, cable
shafts, drainers.
6.7.1.10 Openings of adequate size should be provided
for intake of fresh air. Fresh air intake shall have
louvers having rain protection profile, with volume
control damper and bird screen.
6.7.1.11 Outdoor air intakes and exhaust outlets shall
be effectively be shielded from weather and insects.
6.7.1.12 In all cases air intakes shall be so located as
to avoid contamination from exhaust outlets or to from
sources whose contamination concentration levels are
greater than normal in the locality in which the building
is located.
6.7.1.13 Supply/Return air duct shall not be taken
through emergency fire staircase. However, exception
can be considered if fire isolation of ducts at wall
crossings is carried out.
6.7.1.14 Where necessary, structural design should
avoid beam obstruction to the passage of supply and
return air ducts. Adequate ceiling space should be made
available outside the equipment room to permit
installation of supply and return air ducts and fire
dampers at equipment room wall crossings.
6.7.1.15 Access doors to Equipment rooms should be
through single/double leaf type, air tight, opening
outwards and should have a sill to prevent flooding of
adjacent occupied areas.
6.7.1.16 It should be possible to isolate the equipment
room in case of fire. The door shall be fire resistant.
Fire/smoke dampers shall be provided in supply/return
air duct at air handling unit room wall crossings and
the annular space between the duct and the wall should
be fire sealed using appropriate fire resistance rated
material.
6.7.2 In the planning stages itself, provision should
be made for the following (if they are envisaged):
a) Space/routing/supports, etc for ducting; and
b) Openings in walls, slabs, roof etc, for passage
of ducts, pipes, cables, etc, and for air intake,
air exhaust, etc.
6.7.3 Bleed-off and chemical water treatment,
depending on quality of water available for make-up,
should be planned.
7 UNITARY AIR CONDITIONER
7.1 These are self-contained air conditioning units
comprising a compressor and evaporator with fans for
evaporator and air-cooled condenser. Unitary air
conditioners are generally installed in windows and,
therefore, they are also known as window air
conditioners. It is designed to provide free delivery of
conditioned air to an enclosed space, room or zone. It
includes a prime source of refrigeration for cooling
and dehumidification and means for circulation and
filtration of air. It may also include provision to exhaust
room air as also induce fresh air for ventilation in the
room. In addition to basic cooling unit, there are several
other optional features available, such as:
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION
35
a) Means for heating during winter months.
b) Reciprocating or rotary compressor.
c) Swing louvers for better distribution of air in
the room.
d) In addition to normal, dust filters, indoor air
quality filters, such as bactericidal enzyme
filters for killing bacteria, low temperature
catalyst filter for removal of unpleasant
odours, electrostatic filters to trap particles
of smoke as well as suspended matters present
in the air.
e) Digital LCD remote control which also
indicates room temperature.
7.2 Capacity
Most of the manufacturers supply unitary air conditions
in capacities of 3 500 W (1 TR), 5 250 W (1.5 TR) and
7 000 W (2 TR). However, some of them may be able
to supply window air conditioners of 1 750 W (0.5 TR)
and upto 10 500 W (3 TR) alongwith intermediate
range. The capacity of windows air conditioners is
rated at outside dry bulb temperature of 35 °C and wet
bulb temperature of 30°C and they are suitable for
230 V, single phase 50 Hz power supply. Nominal
capacity of all the window air conditioners has to be
de-rated due to high ambient temperatures in summer
months in most of Indian cities. Also, generally a
voltage stabilizer has to be installed to ensure that
window air conditioner gets stabilized rated voltage.
7.3 Suitability
Unitary air conditioners are suitable for bedrooms,
office cabins, general office area, hotel rooms and
similar applications where normal comfort conditions
are required upto a distance of 6 m from unitary air
conditioner.
7.4 Power Consumption
Power consumption of window air conditioners
of 1 TR (3 500 W) rated capacity should not exceed
1.55 kW/TR. However, in smaller sizes, the power
consumption may exceed. Rotary compressors
normally consume 7 percent to 8 percent less power
compared to the above value for reciprocating
compressors.
7.5 Noise Level
Noise level of window air conditioner inside the
conditioned room should be as low as possible.
However it should not exceed 65 dBA for 5 250 W
(1.5 TR) or smaller capacity window air conditioners.
Air conditioners with rotary compressors will have
lower noise level as compared to those provided with
reciprocating compressors.
7.6 Location
Unitary air conditioners should be mounted preferably
at the window sill level on an external wall where hot
air from air-cooled condenser may be discharged
without causing nuisance. There should not be any
obstruction to the inlet and discharge air of the
condenser. Also while deciding location of the window
air conditioners, care should be taken to ensure that
the condensate water dripping does not cause nuisance.
The opening for the air conditioner is generally made
a part of windows or wall construction at the planning
stage.
7.7 Limitations
Room air conditioners are not generally recommended
in the following situations:
a) The width of the area exceeds 6 m.
b) Area requiring close control of temperature
and relative humidity.
c) Internal zones where no exposed wall is
available for the installation of room air
conditioners.
d) Sound recording rooms where criteria for
acoustics are stringent.
e) Special applications like sterile rooms for
hospitals and clean room applications where
high filtration efficiency is desired.
f) Operation theatres where 100 percent fresh
air is needed and fire hazard exists depending
on the type of anaethesia being used.
g) Where required to comply with the
recommended fresh air requirement for
ventilation.
7.8 For detailed information regarding constructional
and performance requirements and methods for
establishing ratings of room air conditioners, reference
may be made to accepted standard [8-3(6)].
8 SPLIT AIR CONDITIONER
8.1 Split air conditioner has an indoor unit and an
outdoor unit interconnected with refrigerant piping and
power and control wiring. Indoor unit comprises of a
filter, evaporator and evaporator fan for circulation of
air in the conditioned space. Outdoor unit has a
compressor, air-cooled condenser with condenser fan
housed in a suitable cabinet for outdoor installation.
Split air conditioner includes primary source of
refrigeration for cooling and dehumidification and
means for circulation and cleaning of air, with or
without external air distribution ducting.
Split air conditioners may be provided with either
reciprocating compressor or scroll compressor. Scroll
36
NATIONAL BUILDING CODE OF INDIA
compressor generally consumes about 10 to 12 percent
less power compared to reciprocating compressor.
Various split air conditioners available may be
categorised as under:
a) Exposed indoor unit, which is either a high
wall unit or a floor-mounted unit.
b) Furred-in units (ceiling suspended unit),
which is mounted in the ceiling and provided
with a duct collar and grille.
c) Ducted indoor unit, which requires ducting
for air distribution.
8.2 Suitability
Split air conditioners are suitable for wide range of
applications including residences, small offices, clubs,
restaurants, showrooms, departmental stores, etc.
8.3 Capacity
Split air conditioners are available in following
capacities:
a) Indoor exposed units, 3 500 W (1 TR),
5 250 W (1.5 TR), 7 000 W (2 TR) or two
indoor units of 3 500 W (1 TR) or 5 250 W
(1 .5 TR), connected with one outdoor unit of
7 000 W (2 TR) or 10 500 W (3 TR) capacity.
These units are available with corded and
cordless remote control.
b) Furred-in Units are available in capacities of
3 500 W (1 TR) and 5 250 W (1.5 TR) and
may be provided with one outdoor unit or two
outdoor units with two furred-in indoor units.
These units are available with corded and
cordless remote control.
c) Ducted split air conditioners (ceiling
suspended ducted units) are available in
capacities of 10 500 W (3 TR), 17 500 W
(5 TR), 26 250 W (7.5 TR) and 52 500 W
(15 TR). Ducted split air conditioners
with scroll compressors are available
in sapacities of 19 250 W (5.5 TR) and
29 750W(8.5TR).
8.4 Location
Split air conditioner indoor unit is mounted within the
air conditioned space or above the false ceiling from
where the air distribution duct is taken to the
conditioned space to distribute the air. When the indoor
unit is mounted in the false ceiling, inspection panel
must be kept in the false ceiling to attend to the indoor
unit including periodic cleaning of air filter. Outdoor
unit is mounted at the nearest open area where
unobstructed flow of outside air is available for air
cooled condenser.
8.5 Installation
Ceiling suspended indoor units are provided with
rubber grommet to reduce vibration. Outdoor units are
mounted on a steel frame in an open area so that the
fan of the air cooled condenser can discharge hot air
to the atmosphere without any obstruction. Care should
be taken to ensure that free intake of air is available to
the outdoor air cooled condenser. Also precaution
should be taken that hot air from any other outdoor
unit does not mix with the intake of the other outdoor
air cooled condenser.
8.6 Limitations
Split air conditioners are generally not recommended
for:
a) For areas where fresh air is required for
ventilation.
b) Where distance between indoor exposed unit
or furred-in unit exceeds 5 m from the outdoor
unit for units up to 7 000 W (2 TR) capacity.
For larger ducted split air conditioners, the
vertical distance between the indoor unit and
the outdoor unit should not exceed about 6 m
for units with reciprocating compressors. The
horizontal distance between the indoor unit
and outdoor unit should not exceed about
10 m for reciprocating compressors.
c) Area requiring close control of temperature
and relative humidity.
d) Sound recording rooms where criteria for
acoustics are stringent.
e) Special applications like sterile rooms for
hospitals and clean room applications where
high filtration efficiency is desired.
f) Large multi-storey buildings where multiplicity
of the compressors may entail subsequent
maintenance problems.
g) Where the length of air distribution ducting
may exceed about 20 m.
8.7 Reference may be made to accepted standard
[8-3(7)].
9 PACKAGED AIR CONDITIONER
9.1 Packaged air conditioner is a self-contained unit
primarily for floor mounting, designed to provide
conditioned air to the space to be conditioned. It
includes prime source of refrigeration for cooling and
dehumidification and means for circulation and
cleaning of air, with or without external air distribution
ducting. It may also include means for heating,
humidifying and ventilating air.
The unit comprises a compressor, condenser and
evaporator, which are interconnected with copper
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION
37
refrigerant piping and refrigerant controls. It also
includes fan for circulation of air and filter. The unit is
provided with compressor and fan motor starter and
factory-wired safety controls.
Compressor is a device, which compresses low-
pressure low temperature refrigerant gas to high-
pressure high temperature super heated refrigerant gas.
Compressors may be reciprocating type or scroll type
for packaging unit applications.
Condenser condenses high pressure high temperature
refrigerant gas to liquid refrigerant at approximately
the same temperature and pressure by removal of
sensible heat of refrigerant by external means of water
cooling or air cooling.
The packaged units are also available with
microprocessor-based controller installed in the unit
for digital display of faults as also several other
functions. The packaged unit can also be provided with
winter heating package or humidification package. The
packaged unit may be provided with either water-
cooled condenser or a remote air cooled condenser with
interconnected copper refrigerant piping. The units are
available with reciprocating compressor as also scroll
compressor, which consume about 10 to 12 percent
lesser power. In a water-cooled condenser unit,
condenser-cooling water is circulated through the
cooling tower with necessary piping and pumpsets.
The water cooled condenser packaged unit gives higher
capacity at lower power consumption as compared to
an air cooled condenser packaged unit which gets
considerably de-rated in capacity and also consumes
more power in peak summer months in most of the
cities of our country due to high ambient temperature.
Packaged units are generally available with vertical
air discharge or horizontal air discharge.
9.2 Suitability
Packaged units are suitable for wide range of
applications including offices, clubs and restaurants,
showrooms and departmental stores, and computer
rooms, etc.
9.3 Capacity
Normally the packaged air conditioners are manufactured
in sizes of 17 500 W (5 TR), 26 250 W (7.5 TR),
35 000 W (10 TR) and 52 500 W (15 TR). Packaged
units with scroll compressors are also available in
capacity up to 58 100 W (16.6 TR).
9.4 Location
The packaged unit can be mounted within the air
conditioned space with discharge air plenum or in a
separate room from where the air distribution duct is
taken to the conditioned space. While deciding location
for the packaged unit, provision must be kept for proper
servicing of the unit.
9.5 Installation
The packaged units are normally mounted on a resilient
pad which prevents vibration of the unit from being
transmitted to the building.
9.6 Limitations
Packaged air conditioner are not generally recommended
for:
a) Large multi-storey buildings where multiplicity
of the compressors may entail subsequent
maintenance problems.
b) Where the length of air distribution ducting
may exceed approx 20 m.
c) Where the vertical distance of air-cooled
condenser from the packaged unit exceeds
about 10 m. The sum of horizontal and vertical
distances should be generally kept within 15 m.
d) Special applications like sterile rooms for
hospitals and clean room applications where
high filtration efficiency is desired.
e) Operation theatres where 100 percent fresh
air is needed and fire hazard exists depending
on the type of anesthesia being used.
9.7 For detailed information regarding constructional
and performance requirements and methods for
establishing ratings of packaged air conditioners,
reference may be made to accepted standard [8-3(8)].
10 HEATING
10.1 The installations for air conditioning system may
be used advantageously for the central heating system
with additions such as hot water or boiler and hot water
coils or strip heater banks.
10.2 The heating equipments as described in 10.2.1
and 10.2.2 are generally used;
10.2.1 Hot Water Heated Coils
Central heating systems'using hot water usually
required not more than one or two rows of tubes in the
direction of air flow, in order to produce the desired
heating capacity. To achieve high efficiency without
excessive water pressure drop through the coil, various
circuit arrangements are used.
Generally, the resistance to the hot water flow through
the heater should not exceed 4 kPa in low pressure hot
water heating installations. In high pressure hot water
installations, the resistance to the water flow will
probably be determined by other factors, for example,
the need to balance circuits.
38
NATIONAL BUILDING CODE OF INDIA
The heaters should be served from hot water flow and
return mains with sufficient connections to each row
or bank of tubes or sections to give uniform distribution
of the heating medium.
The flow connections to the heater should generally
be arranged at the lowest point of the heater, and the
return connections at the highest, to aid venting. The
expansion of the tubes when the heater is in operation
should be considered and the necessary arrangements
made to accommodate expansion and contraction.
Thermometer wells should be fitted in the pipes near
the inlets and outlets of all air-heating coils so that the
temperature drop through the heater can be readily
observed.
10.2.2 Electric Air Heater
The air velocity through the heaters should be sufficient
to permit the absorption of the rated output of the finned
tube heaters within its range of safe temperatures and
the exact velocity determined in conjunction with the
manufacturers of the heater. Electrical load should be
balanced across the three-phase of the electrical supply.
Where automatic temperature control is required
the heater should be divided into a number of
sections dependent upon the degree of control to be
effected.
Each section of heater elements, which may be two
rows of elements should have its own busbars and
connection and be capable of withdrawal from the
casing, thus enabling the elements to be cleaned or
repaired whilst the remainder is in operation. Each
section should be capable of being isolated electrically
before being withdrawn from the casing.
All heaters should be electrically interlocked with the
fan motors, so that the electric heater will be switched
off when the fan is stopped or when the air velocity is
reduced to a level below that for which the heater has
been designed.
The air velocity over the face of the heater is of
particular importance in the design of electric air
heaters, and the manufacturers should be given details
of the maximum and minimum air velocities likely to
occur.
With all electric air heaters, care should be taken to
preclude the risk of fire under abnormal conditions of
operation, by the use of a suitably positioned
temperature sensitive trip of the manual reset type to
cut off the electric supply.
11 SYMBOLS, UNITS, COLOUR CODE AND
IDENTIFICATION OF SERVICES
11.1 Units and symbols to be used in air conditioning,
ventilation and refrigeration system shall be in
accordance with good practice [8-3(9)].
11.2 Colour code for identification for various items
in air conditioning installations for easy interpretation
and identification is advisable. This shall promote
greater safety and shall lessen chances of error,
confusion or inaction in times of emergency. Colour
shade shall be generally in accordance with good
practice [8-3(10)].
11.3 Colour bands shall be 150 mm wide,
superimposed on ground colour to distinguish type
and condition of fluid. The spacing of band shall not
exceed 4.0 m.
11.4 Further identification may also be carried out
using lettering and marking direction of flow.
11.5 Services Identification
11.5.1 Pipe Work Services
11.5.1.1 The scheme of colour code for painting of
pipe work services for air conditioning installation shall
be as indicated in Table 7.
11.5.1.2 In addition to the colour bands specified
above, all pipe work shall be legibly marked with black
or white letters to indicate the type of service and the
direction of flow, identified as follows:
High Temperature Hot Water HTHW
Medium Temperature Hot Water MTHW
Low Temperature Hot Water LTHW
Chilled Water CHW
Condenser Water CDW
Steam ST
Condensate CN
11.5.2 Duct Work Services
11.5.2.1 For duct work services and its insulation,
colour triangle may be provided. The size of the
triangle will depend on the size of the duct and viewing
distance but the minimum size should not be less than
150 mm length per side.
The colour for various duct work services shall be as
given below:
Services
Colour
Conditioned Air
Red and Blue
WardAir
Yellow
Fresh Air
Green
Exhaust/Extract/Recalculated Air
Grey
Foul Air
Brown
Dual Duct System
Hot Supply Air
Red
Cold Supply Air
Blue
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION
39
Table 7 Scheme of Colour Code of Pipe Work Services for Air Conditioning Installation
(Clause 11.5.1.1)
Si No.
Description
Lrround Colour
Lettering Colouring
first Colour Band
(1)
(2)
(3)
(4)
(5)
i)
Cooling water
Sea green
Black
French blue
")
Chilled water
Sea green
Black
Black
iii)
Central heating below 60°C
Sea green
Black
Canary yellow
iv^
CentTA\ hf-atinQ f>0°C tn 100°r
Sea Qreen
Black-
Dark violet
v)
Drain pipe
Black
White
vi)
Vents
White
Black
VUj
vaives anu pipe line nuings
wniie wun oiacK nanuies
DiaCK
viiU
Relr Piiarrl
Rlark vpIIow (iiacnnal
srrins
IX)
Machine bases, inertia bases and
plinth
Charcoal grey
Each valve shall be provided with a label indicating
the service being controlled, together with a reference
number corresponding with that shown on the Valve
Charts and ; as fitted' drawings. The labels shall be
made from 3 ply (biack/white/biack) traffoiyte
material showing white letters and figures on a black
background. Labels shall be tied to each valve with
Curoniium piateu iinKcu cnain.
12 ENERGY CONSERVATION, ENERGY
MANAGEMENT, AUTOMATIC CONTROLS
AND BUILDING MANAGEMENT SYSTEM
12.1 In the context of this Code, energy conservation
signifies the optimum use of energy to operate the air
conditioning, healing and ventilation system of a building.
12.2 It is axiomatic that general standards of comfort
or specific environmental requirements within the
building should not be compromised in an endeavour
to achieve lower consumption of energy. Similarly
nothing in this Code overrides regulations related to
health and safety.
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12.3.1 Energy Targets
For the purpose of assessing energy conservation
efficiency of one system design against another, or in
an existing building comparing one period of energy
use against another, target consumptions may be
established.
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Energy demand is mainly determined by location of
the building, its structure and the equipment installed
within it. Demand targets are readily applied to designs
for new buildings and are quoted as an 'average rate'
of energy use (W/'m 2 ).
12.3.3 Consumption Targets
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12.3.4 Air Conditioning/Ventilation
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12.3.5 The design of the system and its associated
controls should take into account the following:
a^
The nature of the amplication;
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c) External and internal load patterns;
d) The desired space conditions;
e) Permissible control limits;
f) Control methods for minimizing use of
primary energy;
g) Opportunities for heat recovery;
h) Economic factors (including probable future
cost and availability of fuel).
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12.3.6 The operation of the system for the following
conditions has to be considered when assessing the
complete design:
a) in summer;
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Cy in inieriTieviiaLe seasons;
d) at night;
e) at weekends; and
f) restoration of power supply after intermittent
failure.
12*3*7 Consideration should be °iven to chan a es in
hnilHina load in the svstp.tn design so fhat maximum
operational efficiency is maintained under part
load conditions. Similarly, the total system should
be separated into smaller increments having
similar load requirements so that each area can be
separately controlled to maintain optimum operating
conditions.
12.3.8 The temperature of heating or cooling media
circulated with in the system should be maintained at
the level necessary to achieve the required output to
match the prevailing load conditions with the minimum
consumption of energy.
12.3.9 Energy recovery has to be maximized.
12.3.10 Operation and maintenance procedures have
to be properly planned.
12.3.11 Equipment Consideration
12.3.11.1 All equipment and components should be
tested in accordance with the relevant Indian Standards;
where no applicable standard exists, an agreed
international or other standard and test procedure may
be adopted.
12.3.11.2 The equipment suppliers should furnish
upon request the energy input and output of the
equipment, which should cover full and partial loads
and standby conditions as required in order that the
energy consumption can be assessed over the whole
range of operating conditions.
12.3.11.3 Where components from more than one
supplier are used in combination, for which published
performance data do not exist then the system designer
should take the responsibility for ensuring that their
combination leads to optimum energy use.
12.3.11.4 Equipment preventive maintenance schedule
should be furnished along with all other required
information.
12.4 Control System
The designer should aim to select the simplest system
of control capable of producing the space conditions
required. It is uneconomical to provide controls with a
degree of accuracy greater than the required by the
application. Consideration should be given to the
provision of centralised monitoring and control, thus
achieving optimum operation.
12.5 Automatic Controls and Building Management
System
12.5.1 Types of Equipment
The basic components that are designed, selected to
work together to form a complete control system,
together with their function, are shown as follows:
The basic components of a control system are:
Element or Component
Sensing and measuring
element of the controller
(for example, sensor,
transmitters, transducers,
meters, detector)
Controller mechanism
Connecting members of
the control circuit; wiring
for electric linkages for
mechanical devices
Controlled devices or
actuator such as motor
or valve
Controller mechanism,
connecting means, and
actuator or control device
Function
Measuring changes in
one or more controlled
conditions or variables.
Translating the changes
into forces or energy of a
kind that can be used by
the final control element.
Transmitting the energy
or forces from the point
of translation to the point
of corrective action.
Using the force or energy
to motivate the final
control element and effect
a corrective change in the
controlled condition.
Terminating the call for
corrective change, to
prevent over-correction.
12.5.2 Sensing and Measuring Elements
12.5.2.1 Temperature elements
a) A bimetal element comprises two thin strips
of dissimilar metals fused together and
arranged as a straight, U-shaped or spiral
element. The two metals have different
coefficients of thermal expansion, so a change
in temperature causes the element to bend and
produce a change in position.
b) A rod and tube element is composed of a high
expansion metal tube inside which is located
a low expansion rod with one end fixed to
the rear of the tube so that temperature
changes cause the free end of the rod to move.
c) Sealed bellows element is evacuated of air and
charged with a liquid, gas or vapour, which
changes in pressure or volume as surrounding
temperature changes to result in change of
force or movement.
d) Remote bulb element consists of a sealed
bellows or diaphragm to which a bulb or
capsule is attached by means of capillary
tubing, the entire system being filled with
liquid, gas or vapour. Temperature changes
at the bulb are communicated as pressure or
volume changes through the capillary tube to
the bellows or diaphragm.
e) Resistance temperature detectors (RTDs) are
temperature sensors containing either a fine
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION
41
wire or a thin metallic element whose
resistance increases with temperature and
varies in a known manner. RTDs are
characterised by their high degree of linearity,
good sensitivity and excellent stability. RTDs
are used with electronic controllers,
f) Thermocouple element comprises a junction
between two dissimilar metals that generates
a small voltage related to the temperature.
12.5.2.2 Humidity devices
a) These devices have a hygroscopic organic
polymer deposited on a water permeable
substrate. The polymer film absorbs moisture
until it is in balance with the ambient air. This
causes a change in resistance or capacitance.
b) Resistance elements, as employed in electronic
systems, consist usually of two interleaved
grids of gold foil, each connected to a terminal
and mounted on a thin slab of insulating
plastic material with a coating of hygroscopic
salt (lithium chloride) on the block. A
conductive path between adjacent strips of foil
is formed, and the high electric resistance of
this circuit changes as the chemical film
absorbs and releases moisture with changes
in the relative humidity of surrounding air.
12.5.2.3 Pressure elements
a) Low-pressure measuring elements for low
positive pressure or for vacuum conditions,
for example, static pressure in an air duct,
usually comprise a large slack diaphragm, or
large flexible bellows. In one type of static
pressure regulator two bells are suspended
from a lever into a tank of oil, so that positive
pressure under one of the bells moves the bell
and lever up (or down) to complete an electric
circuit. The majority of these elements sense
differential pressure, and when combined
with pitot tubes, orifice plates, and venturi
meters may be used to measure velocity, flow
rate or liquid level.
b) High-pressure measuring elements, for
pressure or vacuum measurements in the kPa
range, are usually of bellows, diaphragm or
Bourdon tube type. If one side of the element
is left open to atmosphere the element
will respond to pressure above or below
atmospheric.
12.5.2.4 Special elements
a) Special elements for various measuring or
detecting purposes are often necessary for
complete control in air conditioning or
ventilating systems, for example a 'paddle-
blade' type of air flow switch may be
interlocked with an electric heater battery
to prevent battery from operating and
overheating in the event of an air flow failure.
b) Other elements employed from time-to-time
are measuring smoke density, carbon monoxide
(for example in road traffic tunnels or
underground car parks) and carbon dioxide,
and for flame detection.
12.5.2.5 Controllers
Controlling elements normally regulate the application
of either electrical or pneumatic energy. Controllers
are mainly of three types: thermostat, humidistats and
pressure controllers.
12.5.2.6 Thermostats
The following types of thermostats are in common use:
a) The room type responds to room air temperature
and is designed for mounting on a wall.
b) The insertion thermostats respond to the
temperature of air in a duct and are designed
for mounting on the outside of a duct with its
measuring element extending into the air
stream.
c) The immersion type responds to the temperature
of a fluid in a pipe or tank is designed for
mounting on the outside of a pipe or tank
with a fluid-tight connection to allow the
measuring element to extend into the fluid.
d) The remote bulb thermostat is used where the
point of temperature measurement is some
distance from the desired thermostat location,
which may often be in central panel. A
differential type employing two remote bulbs
may be used to maintain a given temperature
difference between two points.
e) The surface type is designed for mounting on
a pipe or similar surface and measuring its
temperature, or to give an approximate
measurement of temperature of the fluid with
in the pipe.
f) The day/night room thermostat is arranged to
control at a reduce temperature at night, and
may be changed from day to night operation
at a remote point by hand or time clock, or
from a time switch built into the thermostat
itself.
g) The heating/cooling (or summer/winter)
thermostat can have its action reversed and,
where required, its set points raised or lowered
by remote control. This type of thermostat is
used to actuate controlled devices, such as
42
NATIONAL BUILDING CODE OF INDIA
valves or dampers, that may regulate a heating
medium at one time and cooling medium at
another,
h) The multi-step thermostat is arranged to
operate in two or more successive steps,
j) A master thermostat measures conditions at
one point of another (sub-master) thermostat
or controller.
12.5.2.7 Humidistats
Humidistats may be of the room or insertion type. For
example, a sub master room humidistat may be used
with an outdoor master thermostat to reduce humidity
in cold weather and prevent condensation on windows.
A wet-bulb thermostat is often used for accurate
humidity control, working in conjunction with a dry
bulb controller.
12.5.2.8 Pressure controllers
Pressure or static pressure controllers are made for
mounting directly on a pipe or duct. The controller
may also be mounted remotely on a panel.
12.5.2.9 Controlled devices
12.5.2.9.1 Automatic control valves
An automatic control valve consists of a valve body to
control the flow of fluid passing through it by use of a
variable orifice that is positioned by an operator in
response to signals from the controller. The fluid
handled is generally steam or water, and the operator
is usually of the electric motor or pneumatic actuator
type. As 75 percent or more of all air conditioning and
mechanical ventilation systems utilize a valve of some
sort as the final control element, proper control valve
selection is one of the most important factors in
attaining good systems performance.
Following are the details of various valve types and
valve operators:
a) Valve types — The main type and their
characteristics are summarized below:
1) Single seated valves are designed for
tight shut-off.
2) Double seated valves are designed so that
the fluid pressure on the two discs is
essential balanced, reducing the power
required to operate; this type of valve
does not provide a tight shut-off.
3) Pilot operated valves utilize the pressure
difference between upstream and
downstream sides to act upon a diaphragm
or piston to move the valve, and are
usually single seated, for two piston
applications only, and used where large
forces are required for valve operation.
4) Low flow valves may be as small as
3 mm port size and are used for accurate
control of low flow rates.
5 ) Three way mixing valves have two inlets
and one outlet, and operate to vary the
proportion of fluid entering each of the
two inlets.
6) Three way diverting valves have one inlet
and two outlets and operate to divert or
proportion the inlet flow to either of the
two outlets.
7) Two way modulating valves have one
inlet and one outlet and operate to
modulate or proportion the flow through
the heat exchange equipment.
8) Butterfly valves comprise a heavy ring
enclosing a disc that rotates on an axis at
or near its centre and may be used for
shut-off where low differential pressures
exist.
9) Special multi-port valves for various type
of modulating/sequences operation are
available for control of both hot and
chilled water to three and four pipe fan
coil and induction unit systems.
b) Valve operators — Valve operators usually
comprise an electric solenoid, electric motor,
or pneumatic actuator, brief details of which
are given below:
1) A solenoid is a magnetic coil that
operates a movable plunger to provide
two-piston operation.
2) An electric motor is arranged to operate
the valve stem through a gear train and
linkage. Various types are available for
different applications, such as:
i) A unidirectional motor is used for
two position operation, the valve
opening during one half revolution
of the output shaft and closing during
the next half revolution.
ii) A spring return motor for two
position control operation is energized
electrically, driven to one position,
and held there until the circuit is
broken, when the spring returns the
valves to its normal position.
iii) A reversible motor is used for
floating or proportional operation
and can run in either direction and
stop in any position.
3) A pneumatic actuator usually comprises
a spring opposed flexible diaphragm or
bellows connected to the valve stem, so
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION 43
that an increase in air pressure acts on
the diaphragm or bellows to move the
valve stem compress the spring. When
the air pressure is removed the spring will
return the operator to its normal position.
12.5.2.9.2 Automatic control dampers
Control dampers are designed to control the flow of
air in a ductwork system in much the same as an
automatic valve operates in a fluid circuit, that is by
varying the resistance to flow. Following are the details
of various damper valves and damper operators:
a) Damper valves
1) The single blade damper is generally
restricted to small sizes since it does not
provide accurate control. When fitted in
circular ductwork it may be referred to
as a butterfly damper.
2) A multi-leaf damper is two or more
blades linked together, which may be:
i) A parallel action multi-leaf damper,
having its blades linked so that when
operated they all rotate in the same
direction,
ii) An opposed action multi-leaf damper,
having adjacent blades linked to
rotate in opposite directions when
operated.
b) Damper operators
These may be electric motors of the
unidirectional, spring return or reversible type
fitted with suitable linkage mechanisms, or
may be pneumatic actuators of a type
designed for damper operation.
12.5.2.9.3 Centralized control/monitoring equipment
The centralized control system, which is shown
diagrammatically in Fig. 1 , comprises three main parts:
the remote location equipment, the transmission links,
and the central equipment.
12.5.2.9.4 Remote location equipment
This includes:
a) Input devices or sensors, which measure the
condition of a variable;
b) Signal conditioning devices, which convert
the sensor signal to a type compatible with
the requirements of the remote panel,
transmission system, or the central equipment;
c) Output devices, which provide a means for
converting a command instruction, appearing
at the remote panel, into a signal suitable for
performing an operational function on
external equipment; and
Remote data collection panels or remote enclosure,
which act as termination points for the remote ends of
the transmission links and for connections to the remote
input and output devices.
12.5.2.9.5 Transmission links
The transmission links provides the means for
communication between the central equipment and the
remote data collection panel and may be classified
according to a number of variables, which includes:
a) Medium (wires or cables, telephone lines,
micro wave);
b) Transmission mode (one direction only, one
direction at a time, etc);
c) Data sequence (series, for 2-wire, parallel for
multi-conductor etc);
d) Wire or cable types;
e) Signal types; and
f) Message format.
Other considerations include the physical arrangement
of the transmission system, security and supervisory
aspect.
12.5.2.9.6 Central equipment
This may comprise:
a) An interface, which provides a connection
point and the signal conversion between the
central processor and transmission links.
b) The central processor, which is the collection
of equipment at the central control room
containing the logic for management of the
centralized control and monitoring system;
the processor has the means to receive,
transmit and present information, with the
ability to process all data in an orderly
fashion, and may or may not include a
computer.
c) Peripheral devices such as typewriters,
printers, displays (digital type, projectors, or
cathode ray tubes, etc).
12.5.3 Selection Factors
12.5.3.1 Common factors
There are a number of factors to be considered in the
selection of almost all control system components.
These common factors include:
a) Supply and working electricity voltage, phase,
frequency and number of wires;
b) Maximum and/or minimum temperatures,
humidities or pressures to which components
may be subjected;
c) Restrictions or location, mounting positions,
44
NATIONAL BUILDING CODE OF INDIA
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etc, or possible problems due to duct,
vibration etc;
d) Dimensions and mass;
e) Finish and type of enclosure; and
f) Required accessories or fittings.
NOTE — These common factors, should only be used
as a general guide, and control manufacturers should
be consulted in establishing exact requirements.
12.5.4 Sensing/Measuring Elements
Sensing and measuring elements frequently form an
integral part of a controller and the selection factors to
be considered for this arrangement may be as given
in 12.5.3.1. However, a sensor may be designed and
arranged for operation with a remote controller and
other components, in that case some of the more
important selection factors for temperature elements,
for example, may be as follows:
a) Control operations, for example reverse or
direct-acting;
b) Sensing range, adjustable or non-adjustable;
c) Provision for air filter;
d) Pressure output;
e) Provision for branch pressure indication;
f) Application, for example room, duct or
immersion in pipeline;
g) Application, for example room, duct immersion
in pipeline;
h) Electronic;
j ) Function, for example for primary or secondary
control;
k) Temperature range;
m) Authority range of throttling range adjustment;
n) Nominal resistance and sensitivity; and
p) Provision for temperature indication.
13 INSPECTION, COMMISSIONING AND
TESTING
13.1 Inspection, commissioning and testing should be
carried out meticulously if a satisfactory installation is
to be handed over to the client. It should be ensured
that these are carried out thoroughly and all results are
properly documented. It is recommended that the
whole commissioning procedure should be under the
guidance and control of a single authority, to be
identified by the client.
13.2 Inspection and Testing
All equipment and components supplied may be
subjected to inspection and tests during manufacture,
erection/installation and after completion. No
tolerances at the time of inspection shall be allowed
other than those specified or permitted in the relevant
approved standards, unless otherwise stated. Approval
at the time of inspection shall not be construed as
acceptance unless the equipment proves satisfactory
in service after erection.
High pressure air duct system should also be tested in
accordance with the procedures.
13.2.1 Inspection and Testing at Works
The air conditioning system will consist of various
items of equipment produced by various manufacturers.
Each manufacturer should give facilities for the
inspection of his equipment during manufacturing and
on completion, as specified.
13.2.2 Inspection and Testing on Site
Prior to commissioning, testing, adjusting and
balancing, preliminary checks and charging of the
complete system should be carried out. It is important
that all water systems should have been thoroughly
flushed through and hydraulically pressure tested to
L5 times the working pressure for a period of not less
than 8 h.
13.3 Commissioning, Testing, Adjusting and
Balancing
13.3.1 Basic Considerations
13.3.1.1 The basic considerations are:
a) to test to determine quantitative performance
of equipment;
b) to adjust to regulate for specified fluid flow
rates and air patterns at terminal equipment
(for example reduce fan speed, throttling etc);
and
c) to balance to proportion within distribution
system (sub mains, branches and terminals)
in accordance with design quantities.
13.3.1.2 The objective of testing, adjusting and
balancing of air conditioning, heating and mechanical
ventilation system shall be to:
a) verify design conformity;
b) establish fluid, flow rates, volume and
operating pressures;
c) test all associated electrical panels and
electrical installation for earthing continuity
and earth resistance;
d) take electrical power readings for each
motor;
e) establish operating sound and vibration
levels;
f) adjust and balance to design parameters; and
g) record and report results as per the specified
formats.
46
NATIONAL BUILDING CODE OF INDIA
13.3.2 System Testing, Adjusting and Balancing
13.3.2.1 Refrigeration plant
The refrigeration plant may be tested for the
following:
a) Adjusting water flow rate through chiller and
condenser by use of balancing valves.
b) Ascertaining the capacity by measurement of
water flow rate and temperature of water at
inlet and outiet of chilling machine.
c) Computation of power consumption.
d) Verifying operating noise level as per
manufacturer instructions.
13.3.2.2 Air system
13.2.2.2.1 Air handlers performance
The testing, adjusting and balancing procedure shall
establish the right selection and performance of the air
handling units with the following results:
a) Air-in dry-bulb and wet-bulb temperature,
b) Air-out dry-bulb and wet-bulb temperature,
c) Leaving air dew point temperature,
d) Fan air volume,
e) Fan air outlet velocity,
f) Fan static pressure,
g) Fan power consumption,
h) Fan speed, and
j) Check for zero water retention in the
condensate drain pan.
13.3.2.2.2 Air distribution
Both supply and return air distribution for each air
handling unit and for areas served by the air handling
unit shall be determined and adjusted as necessary to
provide design air quantities. It shall cover balancing
of air through main and branch ducts.
13.3.2.2.3 Hydronic system
The hydronic system shall involve the checking and
balancing of all water pumps, piping network (main
and branches), heat exchange equipment like cooling
and heating coils, condensers, chillers and cooling
towers in order to provide design water flows.
The essential preparation work, shall be done by the
air conditioning contractor prior to actual testing,
adjusting and balancing and shall ensure the
following:
a) Hydronic system is free of leaks, hydrostatically
tested and is thoroughly cleaned, flushed and
refilled.
b) Hydronic system is vented.
c) Check pumps operation for proper rotation
and motor current drawn etc;
d) Confirm that provisions for tabulation of
measurements (temperature, pressure and
flow measurements) have been made; and
e) Open all shut-off valves and automatic control
valves to provide full flow through coils. Set
all balancing valves in the preset position, if
these values are known. If not, shut all riser
balancing valves except the one intended to
be balanced first.
Balancing work for both chilled water system and
condenser water system shall be carried out in a
professional manner and test reports in the specified
format shall be prepared.
13.4 Controls
Since most of the control equipment used for air
conditioning system is factory calibrated, hence
physical verification before installation shall be carried
out. In addition, manufacturers instructions should be
followed for site calibration, if any.
13.5 Noise and Sound Control
Measurements should be taken with a sound level meter
either using the 'A' weighting scale or to draw up a
noise criteria curve. Measurements should be taken in
the following locations:
a) Plant rooms;
b) Occupied rooms adjacent to plant rooms;
c) Outside plant rooms facing air intakes and
exhausts and condenser discharge, to assess
possible nuisance to adjacent occupied
areas;
d) In the space served by the first grille or
diffuser after a fan outlet;
e) In at-least two of the spaces served by fan
coil units or high velocity system terminal
units (where applicable);
f) In any space; and
g) Air handling unit (AHU) rooms and adjoining
areas.
13.6 Handover Procedure
Handover documentation should contain all
information that the user needs to enable the installation
and equipment to be efficiently and economically
operated and maintained. It should also provide a
record of the outcome of any site testing, balancing
and regulation carried out prior to handover.
Handover documentation should include the
following:
a) Description of the installation, including
PART 8 BUILDING SERVICES — SECTION 3 AIR CONDITIONING, HEATING AND MECHANICAL VENTILATION
47
b)
c)
d)
simplified line flow and balance diagrams for
the complete installation;
As-built installation drawings;
Operation and maintenance instructions
for equipment, manufacturer's service
maintenance manuals, manufacturer's spare
parts list and spares ordering instructions;
Schedules of electrical equipment;
e)
f)
g)
h)
Schedules of mechanical equipment;
Test results and test certificates as called for
under the contract including any insurance or
statutory inspection authority certificate;
Copies of guarantee certificates for plant and
equipment; and
List of keys, tools and spare parts that are
handed over.
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and 'accepted standards'
in the fulfillment of the requirements of the Code. The
latest version of a standard shall be adopted at the time
of enforcement of the Code. The standards listed may
be used by the Authority as a guide in conformance
with the requirements of the referred clauses in the Code.
In the following list, the number appearing in the first
column within parentheses indicates the number of the
reference in this Part/Section.
IS No.
(1) 655 : 1963
(2) 277:2003
(3) 737 : 1986
Title
Specification for metal air
ducts (revised)
Specification for galvanized
steel sheet (plain and
corrugated) (sixth revision)
Specification for wrought
aluminium alloy sheet and
strip for general engineering
purpose (third revision)
IS No.
(4) 3103:1975
(5) 3315: 1994
(6) 1391
(Part 1) : 1992
(7) (Part 2) : 1992
(8) 8148:2003
(9) 4831 : 1968
(10) 5 : 1994
Title
Code of practice for industrial
ventilation (first revision)
Specification for evaporative
air coolers (desert coolers)
(second revision)
Specification for room air
conditioners:
Unitary air conditioners
(second revision)
Split air conditioners (second
revision)
Specification for packaged air
conditioners (first revision)
Recommendation on units and
symbols for refrigeration
Specification for colours for
ready mixed paints and
enamels (fourth revision)
48
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 8 BUILDING SERVICES
Section 4 Acoustics, Sound Insulation and Noise Control
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 PLANNING AND DESIGN AGAINST OUTDOOR NOISE
4 PLANNING AND DESIGN AGAINST INDOOR NOISE
5 RESIDENTIAL BUILDINGS
6 EDUCATIONAL BUILDINGS
7 HOSPITAL BUILDINGS
8 OFFICE BUILDINGS
9 HOTELS AND HOSTELS
10 INDUSTRIAL BUILDINGS
1 1 LABORATORIES AND TEST HOUSES
12 MISCELLANEOUS BUILDINGS
ANNEX A NOISE CALCULATIONS
ANNEX B SPECIFICATION OF SOUND INSULATION
ANNEX C NOISE RATING
ANNEX D OUTDOOR NOISE REGULATIONS IN INDIA
ANNEX E SPECIAL PROBLEMS REQUIRING EXPERT ADVICE
ANNEX F AIR-BORNE AND IMPACT SOUND INSULATION
ANNEX G BASIC DESIGN TECHNIQUES FOR NOISE CONTROL IN
AIR CONDITIONING, HEATING AND MECHANICAL
VENTILATION SYSTEM
ANNEX H SUGGESTED EQUIPMENT NOISE DATA SHEET
LIST OF STANDARDS
5
5
8
11
11
13
16
18
20
21
25
26
28
31
32
33
33
34
41
42
43
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
This Section covers the acoustical, sound insulation and noise control requirements in buildings. Emphasis is
laid on planning of buildings vis-a-vis its surroundings to reduce noise and in addition sound insulation aspects
of different occupancies are covered for achieving acceptable noise level's.
This Section was first published in 1970 and was subsequently revised in 1983. In the last revision mainly the
following changes were made:
a) The approximate measured noise levels due to various types of traffic (air, rail and road) were given;
and planning and design features of buildings against outdoor noise were elaborated;
b) Impact sound insulation in residential buildings was modified to grade system of impact sound insulation;
c) Recommendations regarding planning of open plan schools against noise were given;
d) Planning of office buildings with light weight partitions was specified;
e) Planning and design aspects of hotels and hostels, laboratories and test houses, and other miscellaneous
buildings, such as, law courts and councils chambers, libraries, museums and art galleries, auditoria and
theatres had been given;
f) Hearing damage risk criteria in industrial buildings were modified based on permissible exposure limits
for a steady state noise level; and
g) The public address system was elaborated to cover public address system at passenger terminals.
In this revision, the following important changes have been made:
a) Large number of important definitions have been added in line with the present international practice of
usage of terms in the field of acoustics, sound insulation and noise control.
b) Under Planning and Design against Outdoor Noise, a new clause on Highway Noise Barrier has been
included.
c) The clause on public address system has been deleted.
d) A new clause on cinema has been added.
e) Existing Appendix A 'Constructional Measures for Sound Insulation of Buildings' and Appendix B
'Sound Insulation Values for Various Types of Materials and Construction' have been deleted and the
following new informative annexes have been added:
1) Annex A Noise Calculations
2) Annex B Specification of Sound Insulation
3) Annex C Noise Rating
4) Annex D Outdoor Noise Regulations in India
5) Annex E Special Problems Requiring Expert Advice
6) Annex F Airborne and Impact Sound Insulation
7) Annex G Basic Design Techniques for Noise Control in Air Conditioning, Heating and Mechanical
Ventilation System
8) Annex H Suggested Equipment Noise Data Sheet
There are two types of noises, that is, air-borne and structure-borne noise. To reduce the intensity of air-borne
noise, sound absorbent materials may be used.
An absorbent material is one which reduces the intensity of sound reflected from its surface. It may be applied to
walls, floors, ceilings or used as furnishings to reduce the sound level by absorption. However, the materials
selected for sound absorption shall be consistent with fire safety requirements of the buildings.
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
To reduce the transmission of air-borne noise, sound insulating materials may be used. Sound insulating materials
block the passage of noise through them by virtue of their mass and physical properties. The extent of noise
reduction provided by a single homogeneous panel is proportional to the logarithm of mass per unit area. For
high values of sound insulation, normally heavy panels are required. Thin sheets of materials do not have adequate
mass for providing any appreciable sound transmission loss by themselves. However, when thin sheet materials
are used in a double panel construction with an intervening air cavity, this special construction can give extremely
high sound transmission loss values considering the mass of the partition, if designed properly. Porous materials
lack the mass required to provide any appreciable sound transmission loss, and readily allow sound at most
frequencies to be transmitted through them.
To reduce the transmission of structure-borne noise (such as, noise generated by impacts) special construction
methods and elastic discontinuity in the structure may be used. Structure-borne noise reduction is effected by
corner joints, changes in cross-section, changes in materials, etc, in construction. The reduction by these
construction methods is, however, not appreciable specially when a large amount of noise reduction is required
over a short distance. In such cases, introduction of an elastic discontinuity in the structure can result in a very
large amount of noise reduction. The noise transmission is affected only above a certain lower frequency which
depends on the material thickness and the elastic properties of the material. Bonded fibrous materials, rubber
elastomers, cork, etc, are suitable for curtailing structure-borne noise transmission.
This Section is largely based on the following standards:
IS 1950 : 1962 Code of practice for sound insulation of non-industrial buildings
IS 3483 : 1965 Code of practice for noise reduction in industrial buildings
IS 4954 : 1968 Recommendations for noise abatement in town planning
IS 1 1050 Rating of sound insulation in buildings and of building elements:
(Part 1) : 1984 Airborne sound insulation in buildings and of interior building elements
(Part 2) : 1984 Impact sound insulation
BS 8233 : 1999 Code of practice for sound insulation and noise reduction for buildings
In this revision, opportunity has been taken to update all references to relevant Indian Standards referred to in the
text.
All standards, whether given herein above or cross-referred to in the main text of this Section, are subject to
revision. The parties to agreement based on this Section are encouraged to investigate the possibility of applying
the most recent editions of the standards.
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 8 BUILDING SERVICES
Section 4 Acoustics, Sound Insulation and Noise Control
1 SCOPE
This Section covers requirements and guidelines
regarding planning against noise, acceptable noise
levels and the requirements for sound insulation in
buildings with different occupancies.
2 TERMINOLOGY
2.0 For the purpose of this Section, the following
definitions shall apply.
2.1 Ambient Noise — The sound pressure levels
associated with a given environment. Ambient noise
is usually a composite of sounds from near and far
sources none of which are particularly dominant.
2.2 Audible Frequency Range — The range of sound
frequencies normally heard by the human ear. The
audible range spans from 20 Hz to 20 000 Hz.
2.3 A-Weighted Sound Pressure, p x — Value of
overall sound pressure, measured in pascals (Pa), after
the electrical signal derived from a microphone has
been pased through an A-weighting network.
NOTE — The A-weighting network modifies the electrical
response of a sound level meter with frequency in approximately
the same way as the sensitivity of the human hearing system.
2.4 A-Weighted Sound Pressure Level, L pA —
Quantity of A- weighted sound pressure, given by the
following formula in decibels (dBA):
V =101 °g.o</> A //>„) 2
where
p A - is the A-weighted sound pressure in pascals
(Pa); and
p o = is the reference sound pressure (20 ^Pa).
NOTE — Measurements of A-weighted sound pressure level
can be made with a meter and correlate roughly with
subjective assessments of loudness, and are usually made to
assist in judging the effects of noise on people. The
size of A-weighting in 1/3 octave bands, is shown in
Annex A (see A-5). An increase or decrease in level of
10 dBA corresponds roughly to a doubling or halving of
loudness.
2.5 Background Noise — The sound pressure levels
in a given environment from all sources excluding a
specific sound source being investigated or measured.
2.6 Break-in — Unwanted sound transmission into a
duct from outside.
2.7 Break-out — Unwanted sound transmission from
inside a duct to the outside.
2.8 Broad Band Noise — Spectrum consisting of a
large number of frequency components, none of which
is individually dominant.
2.9 Cross-Talk — Unwanted sound transmission
between one room and another room or space via a
duct,
2.10 Decibels — Ten times the logarithm (to the base
10) of the ratio of two mean square values of sound
pressure, sound power or sound intensity. The
abbreviation for 'decibels' is dB.
2.11 Effective Perceived Noise Level in Decibel
(EPN dB) — The number for rating the noise of an
individual aircraft flying overhead is the effective
perceived noise level in decibels (EPN dB). The~
effective perceived noise decibel value takes into
account the subjectively annoying effects of the noise
including pure tones and duration. In principle, it is a
kind of time-integrated loudness level.
2.12 Equivalent Continuous A-Weighted Sound
Pressure Level, L
Aeq.T
Value of the A-weighted
sound pressure level in decibels (dB) of a continuous,
steady sound, that within a specified time interval, T,
has the same mean squared sound pressure as the sound
under consideration that varies with time, given by the
formula:
*W= 101 °6m
y
T P 2 A (t)
dt
Po
where
p A (t) - is the instantaneous A-weighted sound
pressure in pascals (Pa); and
p o = is the reference sound pressure (20 ft Pa).
NOTE — Equivalent continuous A-weighted sound pressure
level is mainly used for the assessment of environmental noise
and occupational noise exffosure.
2.13 Equivalent Sound Absorption Area of a Room,
A — Hypothetical area of a totally absorbing surface
without diffraction effects, expressed in square metres
(m 2 ) which, if it were the only absorbing element in
the room, would give the same reverberation time as
the room under consideration.
2.14 Facade Level — Sound pressure level measured
1 m to 2 m in front of the facade.
NOTE — Facade level measurements of Z, pA are usually 2 dB to
3 dB higher than corresponding free-field measurements.
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
2.15 Free-Field Level — Sound pressure level
measured outside, far away from reflecting surfaces.
NOTE — Measurements made 1 .2 m to 1 .5 m above the ground
and at least 3.5 m away from other reflecting surfaces are usually
regarded as being free-field measurements. To minimize the
effect of reflections the measuring position should be at least
3.5 m to the side of the reflecting surface (that is, not 3.5 m
from the reflecting surface in the direction of the source).
Estimates of noise from aircraft overhead usually include a
correction of 2 dB to allow for reflections from the ground.
2.16 Frequency — The number of cyclical variations
per unit time. Frequency is generally expressed in
cycles per second (cps) and is also denoted as Hertz
(Hz).
2.17 Impact Sound Pressure Level, L { — Average
sound pressure level in a specific frequency band in a
room below a floor, when it is excited by a standard
tapping machine,
2.18 Indoor Ambient Noise — Pervasive noise in a
given situation at a given time, usually composed of
noise from many sources, inside and outside the
building, but excluding noise from activities of the
occupants.
2.19 Insertion Loss (L^)
Insertion loss is generally defined as the difference, in
decibels, between two sound pressure levels (or power
levels or intensity levels) which are measured at the
same point in space before and after a muffler or any
other noise control device is inserted between the
measurement point and the noise source.
2.20 Noise — Unwanted sound which may be
hazardous to health, intrerferes with communications
or is disturbing.
2.21 Noise Exposure Forecast (NEF) — The noise
exposure forecast at any location is the summation of
the noise levels in EPN dB from all aircraft types, on
all runways, suitably weighted for the number of
operations during day time and night time.
2.22 Noise Rating (NR) — Graphical method for
rating a noise by comparing the noise spectrum with a
family of noise rating curves.
NOTE — Noise rating is described in Annex C.
2.23 Noise Reduction Co-efficient (NRC)
A single figure descriptor of the sound absorption
property of a material. It is the arithmetic mean of the
sound absorption co-efficients at 250, 500, 1 000
and 2 000 Hz rounded off to the nearest multiple
of 0.05.
2.24 Normalized Impact Sound Pressure Level, L n
— Impact sound pressure level normalized for a
standard absorption area in the receiving room.
NOTE — Normalized impact sound pressure level is usually
used to characterize the insulation of a floor in a laboratory
against impact sound in a stated frequency band (see Annex B).
2.25 Octave Band — Band of frequencies in which
the upper limit of the band is twice the frequency of
the lower limit.
2.26 Percentile Level, L^ T — A-weighted sound
pressure level obtained using time- weighting 'F\
which is exceeded for N percent of a specified time
interval.
Example:
L A90 lh is the A-weighted level exceeded for 90
percent of 1 h. Percentile levels determined over
a certain time interval cannot accurately be
extrapolated to other time intervals. Time-
weighting 'F 9 or 'S' can be selected on most
modern measuring instruments and used to
determine the speed at which the instrument
responds to changes in the amplitude of the signal.
Time-weighting l F 9 is faster than *5' and so its
use can lead to higher values when rapidly
changing signals are measured.
2.27 Pink Noise — Sound with an uninterrupted
frequency spectrum and a power which is steady
within frequency band and proportional to centre
frequency. An example is constant power level per
octave band.
2.28 Pure Tone — A sound emitted at a single
frequency.
2.29 Rating Level, L Ar ,T r — Equivalent continuous
A-weighted sound pressure level of the noise, plus any
adjustment for the characteristic features of the noise.
NOTE — This definition is used for rating industrial noise,
where the noise is the specific noise from the source under
investigation.
2.30 Reverberation Time, T — Time that would be
required for the sound pressure level to decrease by
60 dB after the sound source has stopped.
NOTE — Reverberation time is usually measured in octave or
third octave bands. It is not necessary to measure the decay over
the full 60 dB range. The decay measured over the range 5 dB
to 35 dB below the initial level is denoted by T 30 , and over the
range 5 dB to 25 dB below the initial level by T 2Q .
2.31 Sound — A vibrational disturbance, exciting
hearing mechanisms, transmitted in a predictable
manner determined by the medium through which it
propagates. To be audible the disturbance shall have
to fall within the frequency range of 20 Hz to
20 000 Hz.
2.32 Sound Exposure Level, L^ — Level of a sound,
of 1 s duration, that has the same sound energy as the
actual noise event considered.
NATIONAL BUILDING CODE OF INDIA
NOTES
1 The L^ of a discrete noise event is given by the formula:
[ ° h P ° J
where
P A (t)- is the instantaneous A- weighted sound
pressure in pascals (Pa);
t-t { - is a stated time interval in seconds (s) long
enough to encompass all significant sound
energy of the event;
p o - is the reference sound pressure level (20(1
Pa); and
t - is the reference time interval (1 s).
2 L AE is also known as L AX (single-event noise exposure level).
2.33 Sound Power — The acoustic power of a sound
source, expressed in Watts.
2.34 Sound Power Level, L w — The acoustic power
radiated from a given sound source as related to a
reference power level (typically 10~ 12 watts) and
expressed in decibels as:
L w =101og
W
l(T i2
where
W = Acoustic power in watts.
By definition, 1 W therefore corresponds to 120 dB
forL .
w
2.35 Sound Pressure,/; — Root-mean-square value
of the variation in air pressure measured in pascals (Pa),
above and below atmospheric pressure, caused by the
sound.
2.36 Sound Pressure Level, L — Quantity of sound
pressure, in decibels (dB), given by the formula:
L p =10log w (p/p o ?
where
p - is the root mean square sound pressure in
pascals (Pa); and
p = is the reference sound pressure (20 ji Pa).
NOTE — The range of sound pressures for ordinary sounds
is very wide. The use of decibels gives a smaller, more
convenient range of numbers. For example, sound pressure
levels ranging from 40 dB to 94 dB correspond to sound
pressures ranging from 0.002 Pa to 1 Pa. A doubling of sound
energy corresponds to an increase in level of 3 dB.
2.37 Sound Receiver — One or more observation
points at which sound is evaluated or measured. The
effect of sound on an individual receiver is usually
evaluated by measurements near the ear or close to
the body.
2.38 Sound Reduction Index, R — Laboratory
measure of the sound insulating properties of a material
or building element in a stated frequency band.
NOTE — For further information see Annex B.
2.39 Sound Source — Equipment or phenomena
which generate sound. Source room is the room
containing sound source.
2.40 Spectrum — A quantity expressed as a function
of frequency, such as sound pressure versus frequency
curve.
2.41 Standardized Impact Sound Pressure Level,
£ nT — Impact sound pressure level normalized to a
reverberation time in the receiving room of 0.5 s.
NOTE — Standardized impact sound pressure level is used to
characterize the insulation of floors in buildings against impact
sound in a stated frequency band {see Annex B).
2.42 Speech Interference Level (SIL) — A descriptor
for rating steady noise according to its ability to
interfere with conversation between two people. SIL
is the arithmetic average of the sound pressure levels
in the three octave bands with centre frequencies
at 500, 1 000 and 2 000 Hz.
2.43 Standardized Level Difference, Z> nT —
Difference in sound level between a pair of rooms, in
a stated frequency band, normalized to a reverberation
time of 0.5 s.
NOTE — Standardized level difference takes account of all
sound transmission paths between the rooms {see Annex B).
2.44 Structure Borne Noise — Generation and
propagation of time dependent motions and forces in
solid materials which result in unwanted radiated sound.
2.45 Transient Sound — Sound which is audible for
a limited period of time, for example sound from over
flight of an airplane.
2.46 Third Octave Band — Band of frequencies in
which the upper limit of the band is 2 1/3 times the
frequency of the lower limit.
2.47 Threshold of Hearing — The lowest continuous
sound pressure level which will create an auditory
sensation for the average human ear. Any sound below
these levels will be inaudible and any sound above the
threshold will vary in loudness dependent on intensity.
2.48 Vibration Isolation — Reduction of force or
displacement transmitted by a vibratory source, often
attained by use of a resilient mount.
2.49 Wavelength — The length in space of one
complete cycle of a sound wave.
A =
(Speed of sound) _ (C)
(frequency) (/)
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
2.50 Weighted Level Difference, D^ — Single-
number quantity that characterizes airborne sound
insulation between rooms but which is not adjusted to
reference conditions.
NOTE — Weighted level difference is used to characterize the
insulation between rooms in a building as they are; values cannot
normally be compared with measurements made under other
conditions {see good practice [8-4(1)]}.
2.51 Weighted Sound Reduction Index, R v _ Single
number quantity which characterizes the airborne
sound insulating properties of a material or building
element over a range of frequencies.
NOTE — The weighted sound reduction index is used to
characterize the insulation of a material or product that has been
measured in a laboratory (see Annex B).
2.52 Weighted Standardized Impact Sound Pressure
Level, Z/ nT w _ Single number quantity used to
characterize the impact sound insulation of floors over
a range of frequencies.
NOTE — Weighted standardized impact sound pressure level
is used to characterize the insulation of floors in buildings (see
Annex B).
2.53 Weighted Standardized Level Difference,
D nTw Single-number quantity, which characterizes
the airborne sound insulation between rooms
NOTE — Weighted standardized level difference is used to
characterize the insulation between rooms in a building (see
Annex B).
2.54 Weighted Normalized Impact Sound Pressure
Level, L' nw — Single number quantity used to
characterize the impact sound insulation of floors over
a range of frequencies.
NOTE — Weighted normalized impact sound pressure level is
usually used to characterize the insulation of floors tested in a
laboratory (see Annex B).
2.55 White Noise — A noise whose spectrum (level)
density is substantially independent of frequency over
a specified range and has equal power for any range
of frequencies of constant band width.
3 PLANNING AND DESIGN AGAINST
OUTDOOR NOISE
3.1 General
Planning against noise should be an integral part of
town and country planning proposals, ranging from
regional proposals to detailed zoning, and three-
dimensional layouts and road design within built-up
areas. Noise nuisance should be fully recognized in
zoning regulations.
3.1.1 Noise is either generated by traffic (road, rail and
underground railway) or it arises from zones and
buildings within built-up areas (industry, commerce,
offices and public buildings). For planning, the noise
survey should examine all the possible causes of noise
and consider the various factors causing actual nuisance.
3.1.2 Noise by night, causing disturbance of sleep, is
more of nuisance than noise by day. For this reason,
housing colonies that adjoin areas with heavy traffic
movement during the night are liable to cause serious
complaints. Also, the factories that work by night are
liable to cause serious complaints if housing estates
adjoin them. While planning, care should be taken that
housing colonies are adequately setback from busy
airports, state and national highways, factories, main
railway lines and marshalling yards.
3.1.3 There are two aspects of defence by planning. The
first is to plan so as to keep the noise at a distance. Under
this aspect comes the separation of housing from traffic
noise by interposing buffer zones, and the protection of
schools and hospitals by green belts, public gardens,
etc. The second is the principle of shading or screening.
This consists of deliberately interposing a less vulnerable
building to screen a more vulnerable one or by providing
a solid barrier, such as a wall, between the source and
the location to be protected.
3.2 Traffic Noise Levels
3.2.1 For Air Traffic
For guidance, approximate noise levels due to various
types of aircrafts, measured on ground, when the
aircrafts fly overhead at a height of 450 m, are given
in Table 1.
Table 1 Typical Noise Levels of Some
Aircarft Types
(Clause 3.2.1)
SI
No.
(1)
Type of Aircraft
(2)
Flyover Noise Levels at 450 m
with Take-off Thrust (EPN dB)
(3)
i)
ii)
iii)
iv)
Boeing 737
Boeing 747-200
Airbus A 300
Concorde SST
107
103
101
114
3.2.2 For Rail Traffic
Noise levels of some typical railway traffic are given
in Table 2.
Table 2 Typical Noise Levels of Railway Trains
(Clause 3.2.2)
SI
No.
(1)
Type of Train
(2)
Noise Level at 30 m, Measured
on the Side or in the Direction
of Train,® (A)
(3)
i)
ii)
iii)
Steam train, 60 km/h
Diesel train, 60 km/h
Electric train, 60 km/h
85
83
77
NATIONAL BUILDING CODE OF INDIA
3.2.3 For Road Traffic
The level of noise generated by road traffic depends
upon such factors as the number of vehicles passing
per hour, the type of traffic, the preponderance of heavy
vehicles, average speed, gradient and smoothness of
traffic flow. The smoothness of traffic flow also affects
variability of the noise and is governed by such things
as roundabouts and traffic lights, and the volume of
traffic and pedestrian movement with their effects on
stopping, starting and overtaking. The level of traffic
noise fluctuates continuously and the way it does has
a considerable effect on the nuisance caused. For
assessing traffic noise, noise is measured in dB(A).
Because of the fluctuating nature of traffic, noise levels
due to different volumes of traffic flow with a varying
mix of vehicles are given in Table 3.
Table 3 Typical Noise Levels Due to
Free-Flowing Road Traffic
(Clause 3.2.3)
SI
No.
(1)
Type of Traffic
(2)
Lio 30 m from Edge
ofRoad,dB(A)
(3)
i) 5 000 vehicles per 18 hour day 65
(10 percent heavy vehicles), 50 kmph
ii) 10000 vehicles per 18 hour day 70
(20 percent heavy vehicles), 60 kmph
iii) 10000 vehicles per 18 hour day 75
(40 percent heavy vehicles), 80 kmph
iv) 20000 vehicles per 18 hour day 77
(40 percent heavy vehicles), 80 kmph
NOTE — The values are applicable to free flowing traffic
without honking.
3.3 Outdoor Noise Regulations
The outdoor noise regulations in force from time-to-
time shall be complied with (see also Annex D).
3.4 Planning and Design
3.4.1 For Air Traffic
Near airports two sources of aircraft noise should be
considered.
a) Flyover noise — Flyover noise is that which
occurs under flight paths close to airports and
is the most serious and common problem. As
the aircraft passes overhead the noise level at
any particular location rises to a peak and then
decreases.
b) Ground noise — The noise emitted by an
aircraft during ground operations is less
variable in direction than flyover noise, but
is usually of a longer duration.
3.4.1.1 Aircraft noise may disturb sleep, rest and
communication, and as such may be considered
potentially harmful to health. It is important that no
new development is carried out within areas where the
expected noise levels will cause mental and physical
fatigue or permanent loss of hearing. In case
development in such areas is essential, adequate sound
insulation shall be provided for the building.
3.4.1.2 As the problems caused by aircraft noise have
become more acute, a number of methods have been
devised for evaluating noise exposure in the vicinity
of airports. They all combine many factors into a single
number evaluation. A commonly used criterion is the
noise exposure forecast (NEF). The NEF is used
primarily to develop noise contours for areas around
airports. It has been accepted generally that noise
exposure forecast levels greater than NEF 40 are
unacceptable to people while levels less than NEF 25
are normally acceptable.
3.4.1.3 While it is theoretically possible to provide
sufficient insulation to achieve an acceptable indoor
noise environment in the area of very high outdoor
noise, there is a level above which aircraft noise
seriously affects living conditions no matter how much
sound insulation has been applied to the dwelling unit.
For this reason it is recommended that no residential
development be allowed beyond the NEF 35 level.
3.4.1.4 During summer months, the windows are
normally kept open for adequate ventilation. In view
of this, no matter how much sound insulation is
provided for the building structure, the noise level
inside the room can never be less than 10 dB below
the outdoor noise level. For very critical buildings,
such as buildings necessary for maintaining and
supplementing the airport services, and for commercial
development, such as hotels, it is possible to provide
sealed windows and to centrally air-condition the entire
building. However, it is not feasible for most of the
residential developments in the country. In such cases
proper zoning regulations and siting of vulnerable
buildings away from aircraft noise are of vital
importance.
3.4.2 Rail Traffic
This is a very serious source of noise in built-up areas,
both by day and by night, "Railway cuttings reduce the
spread of noise, whereas embankments extend it. The
elevated railway on viaducts or embankment is very
common in built-up areas. The elevation increases
exposure to noise but in addition the construction of
the viaduct may effect the propagation of noise. In this
respect solid embankments are preferable to built-up
arches, which tend to act as sound boxes. Worst of all
are the steel bridges, which greatly magnify the noise
due to vibration. Uphill gradients are another feature
tending to increase noise, especially of heavy goods
trains.
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
3.4.2.1 Wherever possible, no residential or public
building zone should abut onto railway lines, especially
on the marshalling yards which is particularly
objectionable because of the shrill, clanging and
intermittent noise they generate, often at night. The
appropriate zones along side railway lines are industrial
and commercial buildings other than office buildings.
Where these precautions are not practicable and
housing has to abut on to railway lines, every attempt
may be made to house as few people as possible in the
vicinity of the railway lines.
3.4.2.2 Underground transportation system can be a
major cause of disturbance for the neighbouring
community. Very high noise levels are propagated to
long distances by the underground high speed railway,
as a result of wheel rail interaction. Both air-borne noise
and ground or structure-borne vibration are potential
sources of complaints. Noise control measures,
therefore, need to be considered for the following:
a) In stations, where high noise levels are
produced at the arrival and departure of
trains;
b) In tunnels, during high speed train movement;
c) Where an underground rail transit system
passes close to existing structures or high rise
buildings adequate attention should also be
paid to the problem of ground vibration
transmitted to the building, and proper
isolation should be provided for critical areas;
d) Wherever elevated railway tracks are provided,
adequate measures should be taken to avoid
the spread of noise in the surrounding built
up areas; and
e) In transit cars, where sound insulation is of
vital importance to provide comfortable
conditions for the commuters.
3.4.3 Road Traffic
3.4.3.1 Convoys of long distance heavy trucks at night
moving past through built-up areas cause serious noise
complaints. On busy roads, the noise of continuous
traffic may be a worse nuisance than that of railways.
At least the same precautions may, therefore, be taken
in the planning of dwellings in relation to arterial and
trunk roads as with railways. Care may be taken that
local housing roads do not provide short cuts for heavy
traffic through residential areas. Hilly roads present
the additional noise of gear changing. Trees with heavy
foliage planted on both sides of carriageway help
slightly to muffle the noise, provided the foliage
extends for a considerable distance (30 m or above).
3.4.3.2 Road traffic may give rise to serious nuisance
particularly on busy thorough fares, between
continuous high buildings in main streets, at the traffic
lights, near bus stops, on steep slopes and in parking
spaces and enclosed yards.
3.4.3.3 For zoning and planning new buildings in
urban areas it is recommended that external L A10 is
limited to a maximum of 70 dB(A) when the dwellings
are proposed to have sealed windows and 60 dB(A)
when the dwellings are proposed to have open
windows. Indeed it is desirable to confine major new
residential development to locations subject to L A10
levels substantially lower than those given above.
It is recognized, however, that within the large urban
areas, the use of sites where the external L A10 is greater
than 60-70 dB(A) can not always be avoided. In that
case it is suggested to utilize such design solutions as
barrier blocks in order to reduce external L MQ noise
levels to at least 60-70 dB(A) at any point 1.0 m from
any inward looking facade. When the orientation of
site and the density of development are such that this
cannot be fully achieved some form of dwelling
insulation will have to be provided. It should be
appreciated that where open windows are a must, the
occupants would have to put up with discomfort if the
above conditions are not met.
3.4.3.4 Certain other methods can often be utilized to
provide economical and effective protection from noise:
a) Methods may be adopted to improve the
smoothness of flow and reduce number of
stopping and starting. This leads to an
improvement even if it leads to increased
flows. Flow linking of traffic lights, for
example, may reduce noise nuisance.
b) Use of roads passing through residential areas
may be prohibited to heavy commercial
vehicles. An alternative would be to limit use
by commercial vehicles to certain times of
the day.
c) Use of honking may be prohibited near
sensitive buildings, such as hospitals and the
like.
d) Barriers may be provided to shield sites from
noise.
3.5 Zoning
The zoning of the different cities shall be done by the
town planning authorities, taking into account besides
other aspects, the noise levels from different
occupancies. Wherever necessary, experts in the field
may be consulted. For detailed information on noise
reduction for town planning schemes, reference may
be made to good practice [8-4(2)].
3.6 Green Belts and Landscaping
Where relief from noise is to be provided by means of
10
NATIONAL BUILDING CODE OF INDIA
green belts these may be of considerable width and be
landscaped. (In case of railway tracks, a minimum
distance of 50 m to 70 m may be provided between
the buildings and the tracks.) The extent of relief that
may be derived from the above may be estimated only
after considering other environmental factors. Only
thick belts of planting (greater than 30 m) are of real
value. Strong leafy trees may be planted to act as noise
baffles. Shrubs or creepers may also be planted for
additional protection between tree trunks; artificial
mounds and banks should be formed where practicable.
As little hard paving and as much grass as possible
may be used. The creation of green belt is particularly
advisable on the perimeter of aerodromes, along
railway lines and arterial roads, through or past built-
up areas and adjoining noisy industrial zones.
3.7 Highway Noise Barriers
Barriers are often the most effective means of reducing
traffic noise around" residential areas. They have the
great advantage that they generally protect most or all
of the site. In nearly all situations, a well-designed
barrier of even a modest height (say 3 m) can at least
ensure that all areas of open space are free from
excessive noise levels.
There are two types of barriers that can be built to
protect sites; one which are built solely for the purpose
of reducing noise and two, which form part of the
building complex (barrier blocks). Free standing walls
and artificial mounds are typical examples of the first
type while single and multi-storeyed dwellings and/or
garages are the most common form of the second.
Of the two types, barrier blocks are more widely used
because they are cheaper and also tend to form a more
effective barrier overall because of their greater height
and width. Barrier walls or mounds are more limited
in their effect than barrier blocks for they protect little
more than the area of the site close to ground level
essentially because of the lack of height, as continuous
walls much higher than 3 m are often difficult to
construct.
3.8 Special Problems Requiring Expert Advice
The purpose of noise control is to ensure that people
are neither harmed not disturbed by noise. In addition
to provisions given in this Section, special advice may
be required for more complex situations, such as those
listed in Annex E.
4 PLANNING AND DESIGN AGAINST INDOOR
NOISE
4.1 Acceptable Indoor Noise Levels in Buildings
The generally acceptable noise levels inside buildings
are given in Table 4.
Table 4 Acceptable Indoor Noise Levels for
Various Buildings
(Clause 4.1)
SI
Location
Noise Level
No.
dB(A)
(1)
(2)
(3)
i)
Auditoria and conceit halls
20-25
ii)
Radio and TV studios
20-25
iii)
Cinemas
25-30
iv)
Music rooms
25-30
v)
Hospitals and cinema theatres
35^0
vi)
Apartments, hotels and homes
35-40
vii)
Conference rooms, small offices and
libraries
35^0
viii)
Court rooms and class rooms
40-45
ix)
Large public offices, banks and stores
45-50
x)
Restaurants
50-55
4.2 Vulnerable Buildings
Some buildings or parts of buildings are specially
vulnerable to noise, for example, recording and radio
studios, hospitals and research laboratories. These
should not be sited near loud noise sources. Most
vulnerable buildings contain some areas which are
themselves noisy and in such buildings the less
vulnerable elements should be planned to act as noise
buffers. Most noisy buildings also contain quiet
accommodation, which equally may be planned to act
as a buffer between the noisy part of the building and
adjoining vulnerable buildings.
4.3 The details of site and internal planning and
insulation requirements are covered under individual
occupancies (5 to 12) as applicable to the respective
character and sources of noise in different buildings.
4.4 Sound Insulation of Non-Industrial Buildings
by Constructional Measures
The desired (acceptable) noise levels and the
recommended insulation values for the various areas
may be achieved by providing sound insulation
treatments by constructional measures. The details of
the same are given in Annex F. The recommendations
given in Annex F are applicable to non-industrial
buildings like residences, educational buildings,
hospitals and office buildings.
4.5 Special Problems Requiring Expert Advice —
(see 3.8 and Annex E).
5 RESIDENTIAL BUILDINGS
5.1 Sources of Noise Nuisance
5.1.1 Outdoor Noise
The main sources of outdoor noise in residential areas
are traffic (aeroplane, railways, roadways), children
playing, hawkers, services deliveries, road repairs
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
11
blaring loud-speakers and various types of moving
machinery in the neighbourhood and building
operations.
5.1.2 Indoor Noise
5.1.2.1 As far as indoor noises are concerned,
conversation of the occupants, footsteps, banging of
doors, shifting of the furniture, operation of the cistern
and water closet, playing of radio, television, music
system, cooling and ventilation machinery, etc,
contribute most of the noise emanating from an
adjacent room or an adjacent building. Noise
conditions vary from time-to-time and noise which may
not be objectionable during the day may assume
annoying proportions in the silence of the night when
quiet conditions are essential.
5.1.2.2 In the case of flats the main sources of noise
are from other flats and from stairs, lifts and access
balconies. Plumbing noise is another cause. In semi-
detached buildings, outdoor noises from streets are
noticed more than indoor noises from neighbours.
5.2 Recommendations
5.2.1 Site Planning
The most desirable method is to locate the residential
buildings in a quiet area away from the noisy sources
like the industrial areas, rail tracks, aerodromes, roads
carrying heavy traffic, etc.
5.2.1.1 To minimize ground reflection, the dwellings
should be surrounded by the maximum amount of
planting and grassed areas and the minimum amount
of hard surfacing. This applies particularly to high
density areas. Where for maintenance reasons a large
amount of hard paving is necessary, it should be broken
up by areas of planting and grassing. Narrow hard
paved courts should be avoided between adjacent tall
buildings.
5.2.1.2 Roads within a residential area should be kept
to a minimum both in width and length, and should be
designed to discourage speeding. Area-wise planning,
with zones from which vehicular traffic is altogether
excluded will greatly help to reduce noise. Roads with
through traffic should be excluded from residential
areas, but where sites have to be developed adjacent
to existing major roads the same principles should be
observed in the siting of blocks as with railway lines
as covered under 3.4.2.1.
5.2.1.3 Play areas for older children should be sited
as far away from dwellings as possible. Special care
should be taken with old peoples' dwellings. They
should not be placed immediately adjacent to service
entries, play spaces, or to any entrances where children
may tend to congregate.
5.2.2 Internal Planning
The orientation of buildings in a locality should be
planned in such a way as to reduce the noise
disturbance from neighbourhood areas. The non-
critical areas, such as corridors, kitchens, bathrooms,
elevators and service spaces may be located on the
noisy side and the critical areas, such as bedrooms and
living space, on the quiet side.
5.2.2.1 Windows and doors
Windows and doors should be kept away from the
noisy side of the building as given below, wherever
possible:
a) When windows of a building, particularly
those of bedrooms in apartments or flats, face
roads carrying heavy traffic or other noises
where the external noise is of the order of 80
to 90 dB(A), the building should be located
at a distance of about 30 m from the road, but
a distance of 45 m or more, where possible,
should be aimed at for greater relief from
noise;
b) When the windows are at right angles to the
direction of the above type of noise, the
distance from the road should be arranged to
be about 15 to 25 m; and
c) In case another building, boundary wall or
trees and plantations intervene between the
road traffic and the house/flat further noise
reduction is achieved and in such cases the
above distances may be reduced suitably.
5.2.2.2 Layout plans
It is desirable that rooms adjoining party walls and
above^elow party floors should be of similar use. By
this means, bedrooms are not exposed to noise from
adjoining living rooms, and there is less risk of
disturbance of sleep.
In semi-detached houses, the staircase, hall and kitchen
should adjoin each other on each side of the party wall,
thus providing a sound baffle between rooms requiring
quiet conditions.
Bedrooms should not be planned alongside access
balconies, and preferably not underneath them. Where
the approach is by an internal corridor, a sound baffle
may usefully be provided by arranging internal
passages and bathrooms between the corridor and the
living room or bedrooms.
Water-closets should not be planned over living rooms
and bedrooms, whether within the same dwelling or over
other dwellings. Soil pipes should not be carried in ducts
which adjoin living rooms or bedrooms unless the side
of the duct next to these rooms is a solid wall containing
12
NATIONAL BUILDING CODE OF INDIA
m> inspection openings. Refuse chutes should not be
planned next to living rooms or bedrooms.
5,2,3 Sound Insulation
5.2.3. J Reduction of air-borne noise
The weighted sound reduction index, /? w , of partitions
between individual rooms or apartments of a building
unit shall be as given in Table 5. These values may,
however, be suitably increased, where required, for
critical areas.
Table 5 Sound Insulation Between Individual
Rooms (Air-Borne)
(Clause 5.2.3.1)
S! No.
(I)
Situation
(2)
(3)
i) Between the living room in one house or flat 50
and the living room and bedrooms in another
ii) Elsewhere between houses or flats 45
iii) Between one room and another in the same 35
house or flat
NOTES
1 Where communicating doors are provided, all doors should
be so designed as to provide recommended insulation
between the rooms.
2 There are cases when a set of houses or flats have to be
built for the people who work at night and sleep during the
day. It is desirable to consider the design of at least one such
room in each of the houses or fiats which will provide an
insulation of about 45 dB in that room.
3 The insulation values referred to are applicable with doors
and windows shut.
5.2.3.2 Suppression of noise at the source itself
All items of equipment that are potentially noisy should
be selected with care. Water-closet cisterns should not
be fixed on partitions next to bedrooms or living rooms.
Plumbing pipes should be isolated from the structures.
Lift motors should be mounted on resilient supports.
Access doors from machine rooms to internal staircases
should be well fitting and of solid construction. Special
noise control measures may be required for electrical
and mechanical services such as diesei generators,
outdoor air conditioning units, cooling towers, etc.
5,2,3*3 Reduction of air-borne noise transmitted
through the structure
Reduction of air-borne noise requires the use of rigid
and massive wails without any openings. Openings are
the major cause of penetration of noise through a
barrier. While designing it should be borne in mind
that all components should provide a sound transmission
compatible with that of the rest of the barrier so that
an equivalent amount of sound energy is transmitted
through each portion of the barrier.
Ventilating ducts or air transfer openings where
provided should be designed to minimize transmission
of noise. For this purpose, some sound attenuating
devices may be installed in these openings.
All partitions should be sealed effectively where they
butt against rest of the structure. All doors and windows
should be properly gasketed where a high degree of
sound insulation is desired.
5.2.3.4 Reduction of structure -borne noise
This requires the use of discontinuous or non-
homogeneous materials in the construction of the
structure.
5.2.3.5 Reduction of impact noise
The floor of a room immediately above the bedroom
or living room shall provide impact sound pressure
level (L' n » Tw ) not greater than 60 dB. For example,
1 50 mm thick concrete floor with thick carpet (12 mm)
covering would satisfy this requirement,
5.2.3.6 Main staircases in blocks of flats are often
highly reverberant. Some of the surfaces at least (for
example, the soffits of stairs and landings) should be
finished with sound absorbent materials wherever
required.
6 EDUCATIONAL BUILDINGS
6.1 Sources of Noise Nuisance
6.1.1 Outdoor Noise
The outdoor sources of noise produced on school
premises, which cause disturbance within the school,
include the noise arising from playgrounds, playing
fields and open-air swimming pools. Though
playgrounds are used mainly during break periods, they
are also used for games and physical education at times
when teaching is in progress in the adjoining class
rooms.
6.1.2 Indoor Noise
Indoor sources of noise are as follows:
a) Singing, instrumental and reproduced music
which may take place in class rooms and in
dining and assembly hails particularly in
primary schools. In secondary schools,
specialized music rooms are generally
provided;
b) The movement of chairs, desks and tables at
the end of one period may disturb a class
engaged in a lesson in a room below;
c) The shutting and openings of doors and
windows which may occur at any time during
teaching periods;
d) Audio-visual presentations in class rooms;
e) Wood and metal workshops, machine shops
(engineering laboratories), typing rooms etc,
PARI S BUDDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
13
which produce continuous or intermittent
sound of considerable loudness;
f) Practical work carried out in general teaching
areas;
g) Gymnasia and swimming pools;
h) School kitchens and dining spaces where food
preparation and the handling of crockery and
utensils persist for the greater part of the
school day;
j) Corridors and other circulation spaces; and
k) Plumbing and mechanical services.
6.2 Recommendations
6.2.1 Site Planning
Where outdoor noise nuisance exists from local
industry, busy roads, railway, airfields, sport grounds
or other sources beyond the control of the school
authority, school buildings should be sited as far as
possible from the sources of noise.
6.2.1.1 Rooms should be planned in a manner so that
the minimum amount of glazing is placed on the side
facing the external noise.
6.2.1.2 Noises arising from the activities of a school
and from the use of the buildings after school hours
may constitute a nuisance to occupants of surrounding
property; therefore, it is desirable to place playgrounds,
workshops, swimming pools, music rooms, assembly
halls and gymnasia as far away as possible from
buildings which require a quiet environment.
6.2.2 Internal Planning
The following principles should be observed in the
detailed planning of educational buildings:
a) Grouping — Noisy rooms should be separated
from quiet ones, if possible. In general, it is
desirable that rooms should be grouped
together in accordance with the classification
given in 6.2.4.1.
b) Windows and ventilators — Windows of noisy
and quiet rooms should not open on to the
same courtyard or be near to one another.
Roof lights and ventilators over noisy rooms
should be avoided, if they are likely to be a
source of nuisance to adjacent upper floors.
c) Doors — Swing doors into rooms should
only be used where no problem of sound
transmission exists. Reduction of insulation
between rooms and corridors due to doors
must be borne in mind. The type and method
of fitting of doors is important and necessary
care shall be paid in this respect.
d) Sliding partitions should only be used where
essential.
e) Open planning and circulation areas —
Where open planning is used to permit
spaces, such as assembly halls, dining rooms
or entrance halls to be used in association
with each other or for circulation, the degree
of disturbance caused by interfering noise
to teaching areas needs careful consideration;
traffic through such areas should be strictly
controlled; full use should be made of
sound absorbent treatments to reduce the
spread of noise from one space to another
(see 6.2.3).
If rooms have large glazed panels or ventilation
openings facing directly on the circulation
areas, human traffic passing by the rooms
should be controlled. Preferably baffled
ventilation system or double windows should
be used. (Fan-lights over doors should be
fixed and glazed).
f) Furniture — In all educational buildings,
regardless of the character of the floor finish,
rubber buffers should be fitted to the legs of
chairs and tables.
6.2.3 Noise Reduction within Rooms
Sound absorbent materials play a useful part in
reducing the built-up or air-borne noise at source. In
rooms, such as, classrooms, assembly halls and music
rooms, a fairly short reverberation time under occupied
conditions is one of the requirements of the acoustic
design. The maximum reverberation times permissible
for this purpose are usually short enough to give
adequate noise control but in addition, the reverberation
time should not be excessive under empty conditions,
because noise may occur in these rooms with very few
occupants. Table 6 gives the reverberation times often
arranged in occupied rooms for acoustic reasons and
the maximum times recommended in the empty rooms
for noise reduction; the times given are for a frequency
of 500 Hz, but they should not be greatly exceeded at
any frequency. When rooms are used for a variety of
purposes, the reverberation period appropriate to the
major use should be adopted.
6.2.3.1 Special attention should be given to noise
reduction in schools for the deaf and schools for the
blind. Deaf children are taught by means of hearing
aids which cannot be used satisfactorily in high noise
levels or in reverberant conditions. Blind children
depend on good hearing for understanding speech and
for detecting changes in environment. In both these
types of schools, noise levels should be kept low and
reverberation times short. As an example, the
reverberation times in empty class-rooms should
not exceed one second in schools for the blind or
0.5 second in schools for the deaf.
14
NATIONAL BUILDING CODE OF INDIA
Table 6 Reverberation Times in Schools
(Clause 6.2.3)
Si
No.
(I)
Room
(2)
Reverberation Time, s
Usual for Maximum for
Acoustic Noise Control
Reasons (Full) (Empty)
(3) (4)
i) Assembly halls
1.0-1.25
1.5-2.5
according
according to
to size
volume of hall
ii) Music teaching rooms
0.75-1.25
1.5
iii) Gymnasia and indoor
—
1.5
swimming pools
iv) Dining rooms
—
1.25
v) Classrooms
0.75
1.25
vi) Headmasters room and
0.5-1.00
1.0
staff rooms
are desirable
1} Shorter reverberation times
for noise control
whenever possible.
6.2.4 Sound Insulation
6.2.4.1 Air-borne noise
For purposes of sound insulation, rooms in educational
buildings may be classified as follows:
Class A
Noise Producing
Workshops
Kitchens
Dining rooms
Gymnasiums
Indoor swimming
pools
Class B
Producing but
Assembly halls
needing quiet at
Lecture halls
times
Music rooms
Typing rooms
Class C
Average
General classrooms
Practical rooms
Laboratories
Offices
Class D
Rooms needing
Libraries
quiet
Studies
Class E
Rooms needing
Medical rooms
privacy
Staff rooms
6.2.4.2 The recommended minimum sound reduction
(D ) between rooms of the same class is as follows:
25 dB
Class A
Class C or D
Class B or E
35 dB
45 dB
6.2.4.3 Where a room is likely to have a dual use, for
example, a dining room to be used as a classroom, the
higher sound insulation value should be used.
6.2.4.4 The recommended minimum sound reduction
(£> w ) between rooms in different classes is 45 dB
subject to the following:
a) In schools or institutes with a technical bias
where noisy activities, such as sheet metal
work, plumbing and woodwork, are likely to
be practised extensively in normal hours,
workshops should be regarded as a special
category requiring more than 45 dB isolation
(D w ) from rooms of any other class.
b) Assembly halls and music rooms are special
cases in that, as well as producing noise, they
also require protection from it and may need
more than 45 dB isolation (£> w ) from rooms
in Class A, if the latter are very noisy.
c) Circulation spaces may vary from a long and
frequented corridor to a small private lobby
and it is therefore difficult to give precise
recommendations to cover them. For partitions
between rooms in Class C and most corridors,
a R w of 35 dB for the partition itself is
adequate. For partitions between rooms in
other classes and corridors, more or less
insulation may be necessary, depending upon
the specific usage.
d) The problem of noise in circulation areas is
as a rule greatly mitigated in schools by the
fact that classes usually change rooms
together at regular times. In colleges and
evening institutes, however, this is much less
true and in such buildings particular attention
should be paid to insulation between rooms
and corridors.
6.2.4.5 Open plan schools
A new concept in school planning is the use of a large
teaching area with simultaneous instructions imparted
to several groups of students. These open plan teaching
areas offer a different set of problems. Because of the
limitations in achieving a great deal of attenuation
across the space and related difficulties in noise control
and speech interference, lecturing to a large number
of students is not possible without interfering with
neighbouring groups. The shape of such spaces may
be as linear as possible with a width to height ratio of
5:1 or greater.
In addition, special measures are required to be
introduced to reduce the level of intruding speech to
an acceptable value so that the various teaching groups
are not disturbed and adequate privacy is maintained.
Judicious positioning of partial height barriers 1.8 m
to 2.1 m in height can improve the sound attenuation
between teaching groups and the use of reflective
screens can reinforce the speech locally without
reflecting it to unwanted areas.
6.2.4.6 Impact noise
In the case of schools, the concrete floor of the room
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
15
immediately above the teaching rooms shall provide
an impact sound pressure level, L' n , Tw not greater than
70 dB. For example, a covering of 6 mm linoleum or
cork tiles on concrete floor (hollow or solid) weighing
not less than 220 kg/m 2 will usually meet the above
requirement.
7 HOSPITAL BUILDINGS
7.1 General
Problems of noise control vary from hospital to hospital
but the principles outlined below apply to all types. A
quiet environment in hospitals is desirable for patients
who are acutely ill. Staff require quiet conditions for
consultations and examinations and also in their living
and sleeping quarters. There have been rapid rises in
noise levels in hospitals due to the higher levels of
outdoor noise, increasing use of mechanical and mobile
equipment (some of which is now brought much nearer
to the patient in order to facilitate nursing procedure)
and the introduction of loudspeaker, radio, television
and call systems. Noise control in the hospital is made
much more difficult by the extensive use of hard
washable surfaces which reflect and intensify the noise.
In most hospitals, windows to the open air and fanlights
to corridors are usually open for the purpose of
ventilation, admitting noise from outside and allowing
it to spread through the building.
7.2 Sources of Noise Nuisance
7.2.1 Outdoor Noise
This may be classified into two main categories:
a) Noise from sources outside the hospital
premises, for example, traffic and industrial
noises; and
b) Noise from sources outside the building but
usually within the control of the hospital
authority, for example, ambulances, motor-cars
and service vehicles, fuel and stores deliveries,
laundries, refuse collection, trucks and trolleys.
7.2.2 Indoor Noise
A hospital is a complex building with many services
and the numerous internal sources of structure-borne
and air-borne noises are grouped into three main
categories:
a) Noise consequent upon hospital routines. This
category includes sources which transmit
noise through both structure-borne and air-
borne paths, many of which may be quite near
to patients particularly those in wards, such
as the following:
1) Wheeled trolleys of various kinds, for
food and medical supplies;
2) Sterilizing equipment;
3) Sluice room equipment including bedpan
washers;
4) Ward kitchen equipment;
5) Footsteps;
6) Doors banging;
7) The handling of metal or glass equipment;
8) Noises caused during maintenance and
overhaul of engineering services; and
9) Vacuum cleaners, mechanical polishers,
etc.
b) Loudspeaker, radio or television, audible call
system, telephone bells and buzzers, and other
air-borne noises, such as loud conversation;
and
c) Noises from fixed or mobile equipment and
services not directly concerned with hospital
routines. These include all the fixed services
as given below:
1) Plumbing and sanitary fittings;
2) Steam hot and cold water and central
heating pipes;
3) Ventilation shafts and ducts;
4) Fans
5) Boilers;
6) Pumps;
7) Air compressors;
8) Pneumatic tubes;
9) Electrical and mechanical motors and
equipment;
10) Lifts;
11) Laundry equipment; and
12) Main kitchen equipment (refrigerators,
mixers, steam boilers, etc).
7.3 Recommendations
7.3.1 Site Planning
Hospital sites with their high degree of sensitivity to
outside noise should be as far away from outside
sources as may be compatible with other considerations,
such as accessibility and availability of services. The
building should be so arranged on the site that sensitive
areas like wards, consulting and treatment rooms,
operating theatres and staff bedrooms are placed away
from outdoor sources of noise, if possible, with their
windows overlooking areas of acoustic shadow.
7.3.2 Detailed Planning
There is a very large number of unit and room
classification in hospital design and in planning the
units in relation to each other and to the common
services (such as X-ray departments, operating theatre
16
NATIONAL BUILDING CODE OF INDIA
suits and main kitchens), noise reduction in the
sensitive areas should be weighed carefully against
other design factors. Special care in overall planning
and internal planning against noise is required in the
planning within the building of units which are
themselves potential noise sources, for example,
children's wards and outpatients' departments, parts
of which require protection against noise.
7.3.2.1 Unloading bays, refuse disposal areas, boiler
houses, workshops and laundries are examples of
service units which should be as far from sensitive areas
as possible.
7.3.2.2 The kitchen is a constant source of both air-
borne and structure-borne noise and should preferably
be in a separate building away from or screened from
the sensitive areas. If this is not possible and the main
kitchens must form part of a multi-storey building,
noise control is easier if they are placed below and not
above the wards and other sensitive rooms so as to
facilitate the insulation of the equipment and machinery
in order to reduce the transmission of structure-borne
noise to a minimum.
7.3.2.3 In ward units, the kitchens, sluice rooms, utility
rooms, sterilizing rooms and other ancillary rooms,
need to be placed quite near to the beds if they are to
fulfil their purposes, which are all sources of noise.
Some form of noise baffling between open wards and
rooms of this kind will be needed.
7.3.3 Reduction of Noise at Source
In view of the difficulty of suppressing noise in hospital
buildings, it is important to eliminate noise at its source
wherever possible.
7.3.3.1 Use of resilient material
Mats of rubber or other resilient material on draining
boards and rubber-shod equipment will greatly reduce
noise from utility rooms, sluice rooms and ward
kitchens. The use of plastics or other resilient materials
for sinks, draining boards, utensils and bowls would also
reduce the noise. Many items of equipment especially
mobile equipment, such as trolleys and beds, may be
silenced by means of rubber-tyred wheels and rubber
bumper and the provision of resilient floor finishes
(see 7.3.4.1). The latter also reduces footstep noise.
Silent type curtain rails, rings and runners should be
used. Lift gates and doors should be fitted with buffers
and silent closing gear. Fans and other machinery should
be mounted on suitable resilient mountings to prevent
the spread of noise through the structure.
7.3.3.2 Other measures
Noise from water or heating pipes may be reduced by
installing systems which operate at comparatively low
pressure and velocities. Silencing pipes and specially
designed flushing action reduce water closet noise at
source and make structural measures easier to apply.
The ventilation system should be designed so as not to
create a noise problem. Silent closers should be fitted
to doors.
7.3.4 Reduction of Noise by Structural Means
7.3.4.1 Insulation
Since the various departments or units may be planned
in many ways, only general guidance on the insulation
values for walls and partitions is given as below:
a) It is recommended that walls or partitions
between rooms should normally have a R w of
at least 40 dB . Higher values of R w of at least
45 dB are necessary where a noisy room is
adjacent to one requiring quiet conditions.
Doors should be solid with close fitting in the
frames.
b) There is little insulation value in double swing
doors and where these are fitted to a noisy
room the opening should be planned so that
it is screened from areas requiring quiet by a
baffle lobby lined with absorbent material.
Very high insulation values may be necessary
in special cases and exceptional measures
may be required.
c) Solid floors with floating finishes and resilient
surfaces are necessary particularly between
wards and other parts of the building.
Ordinary timber board on joist floors should
never be used.
d) Conduits, ventilation ducts, chases, etc,
should be constructed so as not to form easy
by-pass for disseminating noise about the
building, and should be provided with
sufficient sound insulation. Pipe ducts should
be completely sealed around the pipes where
they pass through walls or floors. Ducts
carrying waste or water pipes should be lined
with sound insulating material to prevent
noise from the pipes passing through duct
walls into the rooms through which they pass.
7.3.4.2 Absorption
Most surfaces in hospitals should be easily cleanable,
so as to prevent the build-up of bacteria which may
cause cross-infection. Many sound absorbent materials
of a soft nature and difficult to clean are unsuitable for
use in some hospital areas and lose much of their
effectiveness, if painted for hygienic reasons.
Some porous materials with very thin non-porous
coverings (like mineral wool covered with thin plastic
sheets) have good sound absorption and when covered
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
17
with a perforated sheet metal facing can be used in
most areas requiring a washable acoustical treatment.
In noisy areas, such as corridors and waiting rooms,
however, a wider choice of absorbents is available.
In the ward, bed curtains, window curtain etc, add
to the absorbent properties of the room and help
reduce reverberation in otherwise hard surfaced
surroundings.
7.3.5 Sensitive areas such as operation theatres,
Doctors' consultation rooms, intensive care units (ICU)
require special consideration against noise control.
Apart from outdoor noise, a common problem is the
transmission of sound between the consulting room
and the waiting room. To ensure silence, a sound
isolation D w of 45 dB (A), between the rooms shall be
provided. If the doors are directly connected by a single
communicating door it will not be possible to achieve
these values of isolation D w . To obtain 40-45 dB(A)
insulation between communicating rooms, it is
necessary to provide two doors separated by an air gap,
such as a lobby or corridor.
8 OFFICE BUILDINGS
8.1 General
Modern office buildings are often noisier than older
buildings due to the use of thinner and more rigid forms
of construction, harder finishes, more austere
furnishings and use of business machines.
8.2 Sources of Noise Nuisance
8.2.1 Indoor Noise
Main sources of indoor noise include the following:
a) Office machines, such as typewriters, and
printers;
b) Telephonic conversation;
c) Noise from the public admitted to the building;
d) Footsteps, voices and slamming of doors in
circulation spaces, lift doors and gates;
e) Sound reproduction in staff training rooms,
conference rooms and recreation rooms, etc;
f) Handling of crockery and utensils in canteens
and kitchens; and
g) HVAC and lift machinery.
8.3 Recommendations
8.3.1 Site Planning
Rooms demanding quiet conditions should be placed on
the quiet side of the site. Even on quiet thoroughfares,
these rooms should also not be planned at street level.
They should also not be planned on enclosed yards used
for the parking of cars, scooters, etc. Where, however,
the problems cannot be resolved by planning, the
provision of double windows may be necessary.
8.3.2 Detailed Planning
8.3.2.1 Noise reduction within rooms
The reverberation time should not exceed 1 .0 s in all
general offices of the types listed in 8.3.2.2 to 8.3.2.6.
In small private offices, the reverberation time should
not exceed 0.75 second, in very large offices the
reverberation time may be increased to 1.25 s. For
canteens, the recommended maximum reverberation
time is 1.25 s,
8.3.2.2 Large general offices
The grouping of departments and machines together
in one room should be avoided wherever possible.
Where supervision is necessary the provision of glazed
screens carried up to the ceiling should be considered.
If it is essential to the work of an office for machine
operators and clerks to work side by side in the same
room, the machines should be enclosed by panels or
low screens lined with absorbent material and the
ceiling should be sound absorbent. In addition, the
machines should be as quiet as possible in operation
and mounted on suitable resilient mountings.
NOTE — A quiet area should be planned for prolonged
telephonic conversation.
8.3.2.3 Light weight construction
Modern construction methods and economy dictate the
use of light weight construction for many office
buildings. While the light weight materials lead to fast
fabrication and erection and also effect considerable
economy in the building structure, they may lead to
tremendous sound insulation problems between
adjacent offices and areas. Light weight construction
is also frequently employed for the sub-division of
large space into executive cabins and secretarial areas.
Where such construction is considered desirable,
efforts should be made to provide a double-skin panel.
The panels should be isolated from each other as far
as possible either by the use of separate framing or by
the use of elastic discontinuities in the construction,
and a sound absorbing material may be introduced in
the air cavity between the panel. The partitions should
be full height up to the bottom of the roof above and
any openings required for air movement should be
provided with sound attenuators compatible with the
rest of the partition.
When light weight floors are provided in multi-use
buildings, adequate attention shall be paid to the
question of air-borne and structure-borne noise
transmission from the upper floors to the floors below.
For effective reduction of air-borne noise, a double
panel hollow floor construction may be employed with
18
NATIONAL BUILDING CODE OF INDIA
some heavy sound damping material introduced
between the panels and the panel isolated from each
other. The sound damping material could be sand,
mineral wool, etc. In case impact noise isolation is also
required, the upper panel should be effectively isolated
from the rest of the floors and building structure. The
choice of the isolation layer would of course depend
upon the lowest frequency of interest.
Another point to be kept in mind when going in for
light weight construction is to ensure that the light
weight panels are not in resonance with the natural
frequencies of any mechanical equipment installed
inside the building. Light weight materials have high
natural frequencies well within the audio range and
may resonate or vibrate due to an applied vibratory
force. This vibratory force is caused by mechanical
equipment, road traffic, rail traffic, etc. Special
measures also need be taken to isolate either the source
or the building so as to reduce the amount of vibration
transmitted to the building structure.
8.3.2.4 Open plan offices
A new concept in office planning is the use of open
plan offices. Large open floor spaces are converted
into an office area with senior executives, junior
executives and secretarial staff all seated within the
same area without the use of any partitions or walls.
While this method of planning is appreciated, it leads
to a problem of inadequate acoustical privacy between
adjacent work spaces. Speech privacy in open plan
offices is defined by the speech interference level of
intruding noise. Speech privacy between two adjacent
rooms or spaces is, therefore, a function of two key
parameters; noise reduction of the intervening partition
and background noise levels.
Special design measures are, therefore, required to
reduce the level of intruding sounds at work places to
acceptable low value so that people are not disturbed
and adequate privacy is maintained. Some special
measures which might be considered for such open
plan offices are the use of an acoustical ceiling together
with partial height barriers between work spaces, all
designed to provide adequate privacy between adjacent
work spaces. In addition use may have to be made of
an electronic background masking noise system which
provides a constant level of a generally acceptable
background noise in the entire office area. The masking
noise system is a very useful concept in open plan
office design because by raising the background level
at every workplace, intruding noises are made less
disturbing. A background music system cannot serve
as a noise masking system because the music does not
have a constant spectrum or sound level. In fact the
background noise masking system must be introduced
gradually without the knowledge of employees. The
air conditioning system can also be used to generate
background masking noise if the noise level from the
fans, ducts and grills is suitably tailored to generate
the desired frequency spectrum. However, it is not
simple to predict the noise level of air conditioning
components accurately. On the other hand, the
electronic system enables both the level and the
spectrum of the background noise to be accurately
adjusted to suit individual job requirements.
8.3.2.5 Office equipment rooms
It is important that machines like typewriters, printer,
etc, should be quiet in themselves and also be fitted
with resilient pads, to prevent the floors or tables on
which they stand from acting as large radiating panels.
It is desirable to locate machines further apart and to
apply sound absorbent treatment to the ceiling.
8.3.2.6 Banking halls
If banking halls are large and lofty, noise nuisance
tends to be aggravated. It is advisable to avoid high
reflective ceilings. The worst effects may be reduced
by segregating the noise from the quiet operations and
screening one from the other and by applying sound
absorbent materials to the surfaces of the ceilings,
screens and nearby walls. Resilient flooring is also
recommended.
8.3.2.7 Public offices and waiting spaces
Noise nuisance may be minimized by the provision of
resilient flooring, sound absorbent ceilings and heavy
full height screens between the public space and the
clerical office.
8.3.2.8 Canteens
The provision of a sound absorbent ceiling, resilient
flooring and the use of plastics trays and tables with
'quiet' tops are recommended.
8.3.2.9 Circulation spaces
The effective length of long corridors should be limited
by providing swing doors at intervals. Hard floor
finishes and board and batten floors in corridors should
be avoided. The provision of a sound absorbent ceiling
in corridors is recommended. Floor ducts should be
planned on one side of corridors.
The noise from slamming of doors may be reduced by
fitting automatic quiet action type door closers. Door
buffers are useful but may reduce insulation of air-
borne sound due to the inevitable gaps between buffers.
Continuous soft, resilient strip let into the door frames
is preferable. The use of quiet action door latches is
recommended.
Staircases and lifts should be isolated from quiet rooms
and should have silent type doors.
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
19
8.3.3 Requirement of Sound Insulation
With open window (single or double) the sound
reduction (D ) will be 5-10dB, and with sealed double
windows it will be 40-45dB. Intermediate values are
obtainable with closed openable windows (single or
double) but only, of course, at such times as ventilation
may be dispensed with. Having to choose between
ventilation and noise exclusion is a serious handicap
to efficient working in offices. In large office blocks
on noisy sites, consideration should be given to the
provision of sealed double windows and mechanical
ventilation at least in the offices on the sides of the
building exposed to noise.
8.3.3.1 The insulation necessary between adjoining
rooms, both horizontally and vertically, depends upon
the amount of noise created within the rooms, the
amount of intruding noise and whether it is important
that conversation should not be overheard between
rooms. Generally a sound isolation value (D w ) of 30
dB between one room and another room in office is
recommended.
8.3.3.2 The following list may be considered as broad
classification of noise producing rooms and rooms
requiring quiet though many offices fall into both
categories. Where rooms in opposing categories are
planned adjacent to each other, a sound reduction (D w )
of at least 45 dB should be provided between them.
Noise Producing Rooms Requiring Quiet
Rooms Conditions
Entrance halls, staircases Executive's rooms,
and corridors used by the Conference rooms and
public Board rooms
Lifts and lift halls Interview rooms
Motor and plant rooms Offices for one or two
persons
Lavatories Medical officer' s rooms
Public offices Sick rooms
Canteen and kitchens Rest rooms
Office machine rooms and Libraries
typing pools
Recreation rooms Telephoning rooms
Large general offices
Cinemas and projection
rooms
Av
a) rooms requiring quiet (as listed 45 dB
above) on a quiet site where privacy
is required
b) Rooms requiring quiet (as listed 40 dB
above) but on a noisy site or where
a lower degree of privacy is
tolerable
c) Clerical offices in which noise does 20-30 dB
not constitute a major nuisance
8.3.3.3 It is recommended that the minimum sound
reduction index, R v for floors should be 45 dB, and
the floors should have a resilient finish.
9 HOTELS AND HOSTELS
9.1 General
Hotels and hostels are primarily used as dwelling units,
and hotels also provide for public entertainment. The
most serious risk of course is disturbance to sleep, and
adequate care, therefore, need be taken to protect the
occupants from being disturbed by outdoor and indoor
noise.
9.1.1 Outdoor Noise
Hotels near railway stations, airports, highways and
those situated in highly urbanized areas are specially
vulnerable to outdoor noise. The outdoor noise in many
of the areas is of a high level even late at night and in
the early morning. The noise could also be due to other
types of activities such as building construction activity
(pile driving, concrete mixing etc) and various types
of portable utility equipment, such as compressors or
generators.
9.1.2 Indoor Noise
In so far as indoor noise is concerned, the noise could
be due to the occupants themselves, which is transmitted
from one room to the other. It could also be due to public
functions and late night use of restaurants located in the
hotel as also due to miscellaneous utility equipment
installed for providing and maintaining the services in
the hotel, such as, air conditioning equipment, pumping
equipment, power laundry and kitchen. Sometimes
hotels equipped with standby generators are a potential
source of noise. Another source which could lead to
disturbance to the occupants is the plumbing.
9.2 Recommendations
9.2.1 Site Planning
While it is desirable to locate the hotel, or hostel away
from an area where there is a high ambient noise level,
many a time these have to be located in noisy areas for
public convenience. Hoteis near airports and railway
stations are becoming popular because they are
convenient for passengers in transit. Hotels located in
the commercial areas of a city are also a commercially
viable proposition and many a time this factor
outweighs the other problems associated with such a
location. When a reasonably quiet location is not
possible, it is desirable that adequate measures be
considered to provide a comfortable acoustical
environment for the occupants.
9.2.2 Internal Planning
Where a hotel is located in a noisy environment, the
20
NATIONAL BUILDING CODE OF INDIA
provision of sealed windows (single or double) and
provision of an air conditioning system is desirable
for rooms exposed to noise. The requirements for the
windows would of course depend upon the level and
character of noise in the area.
The general recommendations for satisfactory
acoustical design of hotels and hostels are given
in 9.2.2.1 to 9.2.2.7.
9.2.2.1 Hotels of all classes shall by necessity provide
good protection against indoor noise. Since hotels can
be considered as flats, the standards of protection
recommended for flats are also applicable to hotels.
Partition between guest rooms and between rooms,
corridors and floors shall not be less than 1 1 5 mm brick
wall plastered or equivalent. The floors shall have
proper impact insulation. Special attention should be
paid to built-in wall cupboards as these are potential
areas of sound leakage. These will not serve as sound
insulating partitions and may not be relied upon to
increase the insulation value of partitions against which
they may be built. In fact, partitions between adjoining
rooms should be continuous behind the cupboards. Use
of silent type door gear and cupboard catches is also
highly desirable.
9.2.2.2 Door openings on opposite sides of corridors
shall be staggered and doors be provided with gaskets
on head, sides and threshold. Inter-communicating doors
should be double doors, fully gasketed. Doors should
also have quiet action latches. Whenever possible, rooms
should be entered through a baffle lobby. Wherever
possible, corridor walls should not have ventilators
unless they are double glazed and non-openable.
9.2.2.3 Corridors and staircases may have resilient
floor coverings and sound absorbent ceilings are
desirable unless the corridor is fully carpeted.
Staircases and lift wells may be cut off from corridors
by means of swing doors and, if possible, isolated from
guest rooms by linen stores or similar rooms. Room
service pantries on floors can also be a source of noise
and may be separated from corridors by baffle lobbies,
unless the rooms themselves have baffle lobbies.
9.2.2.4 Except within the same suite, bathrooms
should not be planned next to bedrooms. Where this is
unavoidable, internal pipe shafts with heavy walls,
unpierced on bedrooms side may be used as means of
separation. It is important to choose quiet type of
sanitary fittings and to design the plumbing system so
as not to create noise, that is by avoiding sharp bends,
restrictions of flow, quick-action valves that might
cause water hammer, etc.
9.2.2.5 Air conditioning system should be quiet in
operation. Care should also be taken that the air
conditioning ducts do not lead to a cross-talk problem
between rooms. Suitable acoustical lining would need
to be provided in the ducts consistent with the fire
safety requirements of the buildings.
9.2.2.6 Large hotels often have banquet halls and
conference halls which are separately, hired out for
public and private functions. Late night restaurants and
night clubs are also popular and functions in all these
areas may go on well into the night. It is therefore
essential that these rooms be effectively isolated from
bedrooms and effective insulation from all possible
noise source is ; considered. Here it is not only necessary
to consider the air-borne sound insulation but it is also
necessary to consider the question of structure-borne
and impact noise transmitted from areas where there
might be dancing late into the night.
9.2.2.7 While most of the noise problems encountered
in hotels are applicable to hostels, the latter are
normally of more economical construction and,
therefore, cannot cater for special sound insulation
provisions. However, as far as possible, precautions
should be taken to provide comfortable conditions in
hostel rooms. This is specially true for student hostels
where each room is also a living room. Students might
play music or have loud discussions late into the night.
This may disturb sleep or study of other students.
Proper precautions should, therefore, be taken to
provide satisfactory conditions.
10 INDUSTRIAL BUILDINGS
10.1 General
Industrial buildings are primarily producers rather than
receivers of noise. The level of industrial noise
commonly exceeds that from any other source with
the exception of aircraft. As compared with traffic
noise, its effects are less widespread but it is often more
annoying in character.
10.1.1 Many industrial noises contain very strong high
frequency whines, screeches and clatter — these
components are relatively more attenuated by passage
through the air and by the insulation of light structure
than are lower frequencies.
10.1.2 Intermittent noises arfe either isolated explosions
or reports, or noises of a periodic nature, such as those
of pressure relief valves of blow off, or the noises of
work occurring at random intervals, for example,
hammering, grinding and sawing operations; the latter
class may be especially irritating because of high
frequency components.
10.2 Sources of Industrial Noise
10.2.1 Noises in industrial buildings are mainly of
indoor origin. Noise in factories and workshops is
generally caused by machine tools and by operations
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
21
involved in making and handling the product and they
are classified into the following groups, depending
upon how the noise energy is generated.
10.2.1.1 Impact
Noise caused by impact is the most intense and
widespread of all industrial noises. It is normally
coupled with resonant response of the structural
members connected to the impacting surface. Common
sources of this type of noise are forging, riveting,
chipping, pressing, tumbling, cutting, weaving, etc.
Intense impact noise may also be produced during
handling of materials as in the case of sheared steel
plates falling one over another in collecting trays in a
steel factory. Impact noise is usually intermittent and
impulsive in character, but it may also be continuous
as in the case of tumbling.
10.2.1.2 Friction
Most of the noise due to friction is produced in such
processes as sawing, grinding and sanding. Friction
also occurs at the cutting edge on lathes and other
machine tools and in brakes and from bearings. The
spectrum of frictional noise often predominates in high
frequency and is very unpleasant in character.
10.2.1*3 Rotation and reciprocation
A rotating or reciprocating machine generates noise
due to unbalanced forces and/or pressure fluctuations
in the fluids inside the machines. In many cases, the
moving surfaces radiate noise directly and in other
cases, the pressure fluctuations are transmitted to the
outer casings of the machine from where they are
radiated as noise. Interaction of rotating component
with the fluid stream can also give rise to pure tone
components, such as the whine in a turbine. Since most
machine casings have radiation efficiencies of unity
in the higher frequency range, the amount of sound
radiated is often substantial.
10.2.1.4 Air turbulence
Noise may be generated by rapid variation in air
pressure caused by turbulence from high velocity air,
steam or gases. Common examples are the exhaust
noise from pneumatic tools and air jets. The noise is
intense, and broad based in character and the frequency
criteria depends on the size of the jet. The intensity
increases rapidly with the velocity of the air stream.
10.2.1.5 Noises with pure tone components
Whining noise from turbines and humming noise from
transformers come under this group.
10.3 Noise Criteria
10.3.1 Hearing Damage-Risk Criteria
Continuous exposure to high noise levels may result
in permanent noise induced hearing loss in the course
of time. Damage-risk criteria specify the maximum
levels and duration of noise exposure that may be
considered safe. Generally accepted damage-risk
criteria for exposure to continuous, steady broad band
noise are shown in Table 7. Whenever the sound levels
at the workers position in a factory exceed the levels
and the duration suggested, feasible engineering
controls shall be utilized to reduce the sound to the
limits shown. If such controls fail to reduce sound
levels within the levels of Table 7, personal hearing
protection equipment shall be provided and used to
reduce sound levels within the level shown.
10.3.2 Interference with Communication
In factories where audible warning signals are used,
or where an operator follows the operation of his
machine by ear, the background noise should not be
so loud as to mask the signal or desired sound (the
information sound) to be heard. Noise may be the cause
of accidents by hindering communication or by
masking warning signals.
10.4 Methods of Reducing Noise
10.4.1 Noise Control by Location
Machines, processes and work areas which are
approximately equally noisy should be located together
as far as possible. Areas that are particularly noisy
should be segregated from quiet areas by buffer zones
that produce and may tolerate intermediate noise levels.
10.4.2 Noise Reduction by Layout
The office space in a factory should be as far as possible
located preferably in a separate building. This building
should not have a wall common with the production area.
Where a common wall is unavoidable, it should be heavy
with few connecting doors and no permanent openings.
10.4.3 Noise Reduction at Source
10.4.3.1 Selection of machinery
Noise should be reduced as near the source as possible.
While the operational processes in a factory may be
fixed and may have no/quieter alternative, careful
selection of the machine tools and equipment to be
used may considerably help attaining lower noise levels
in the machine shop.
10.4.3.2 Reducing noise from potential sources
Impact that is not essential to a process should be
quietened. Noise from handling and dropping of
materials on hard surface may be reduced by using soft
resilient materials on containers, fixing rubber tyres on
trucks, trolleys, etc. Machine noise may be kept to a
minimum by proper maintenance. Proper lubrication will
reduce noise by friction conveyors, rollers, etc.
22
NATIONAL BUILDING CODE OF INDIA
Table 7 Permissible Exposure Limits for
Steady-State Noise
(Clause 10.3.1)
Sound Level dB(A)
Time Permitted, T
(Slow Response)
hmin
(1)
(2)
85
16-00
86
13-56
87
12-08
88
10-34
89
9-11
90
8-00
91
6-58
92
6-04
93
5-17
94
4-36
95
4-00
96
3-29
97
3-02
98
2-50
99
2-15
100
2-00
101
1-44
102
1-31
103
1-19
104
1-09
105
1-00
106
0-52
107
0-46
108
0-40
109
0-34
110
0-30
111
0-26
112
0-23
113
0-20
114
0-17
115
0-15
NOTES
1 Where the table does not reflect the actual exposure times
and levels, the permissible exposure to continuous noise at a
single level shall not exceed the time T (in hours) computed
from the formula:
16
2 [0.2 (L- 85)]
where
L is the work place sound level measured in dB(A).
2 When the daily noise exposure is composed of two or more
periods of different levels, their combined effect should be
considered rather than the individual effect of each. The
combined levels may not exceed a daily noise dose, D of unity
where D is computed from the formula:
Z)= C L+ Q + + C JL
where, C v C 2 C n indicate the total duration of
exposure (in hours) at a given steady-state noise level; and T v
T 2 , T a are the noise exposure limits (in hours) for the
respective levels given in the table or computed by the equation
in Note 1. Exposure to continuous noise shall not exceed
115 dB(A) regardless of any value computed by the formula
for the daily noise dose, D or by the equation given in
Note 2.
10.4.3.3 The noise from the radiating surfaces may
be reduced by reducing the radiating area. For example,
if the area is halved, the noise intensity will be reduced
by 3 dB and at low frequencies the reduction will be
much greater.
10.4.3.4 Supporting structures for vibrating machines
and other equipment should be frames rather than
cabinets or sheeted enclosures. If an enclosure is used,
precaution should be taken to isolate it and line it on
the inside with sound-absorbent material. The noise
radiated by machinery guards can be minimized by
making them of perforated sheet or of wire mesh.
10.4.3.5 Reducing transmission of mechanical
vibration
A vibrating sources does not usually contain a large
radiating surface but the vibration is conducted along
mechanically rigid paths to surfaces that can act as
effective radiator. If the rigid connecting paths are
interrupted by resilient materials, the transmission of
vibration and consequently the noise radiated may be
greatly reduced. The reduction depends on the ratio of
the driving (forcing) frequency of the source to the
natural frequency of the resilient system. The natural
frequency may be determined from static deflection
under actual load as given in Fig. 1. Higher the
ratio between the two frequencies, lesser is the
transmissibility, which is defined as the ratio of the
force transmitted through the resilient isolator to the
exciting force applied to it. Transmissibility and the
equivalent noise reduction for various frequency ratios
are given in Fig. 2. For satisfactory operation, a ratio
of 3:1 or more between the driving and natural
frequencies is recommended.
250.00
0.25
4 8 12 16 20 24 283032
NATURAL FREQUENCY IN Hz
Fig. 1 Relation Between Static Deflection
and Natural Frequency
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
23
5.00
3.00
2.00
1.00
0.50
0.30
-
0.20
0.10
0.06
03
-
0.02
CO
8
14
20
28
34
O
8
Z
o
3
UJ
o
2
RATIO
5 6
[ FORCING FREQUENCY
NATURAL FREQUENCY
Fig. 2 Transmissibility and Equivalent Noise
Reduction for Different Ratios of Forcing
and Natural Frequencies
Materials for isolators and their position are given
below:
a) Material for Isolators — Vibration isolators
are usually made of resilient materials like
steel in the form of springs, rubber cork and
felt.
1 ) Because of the large range of deflections
obtainable in coil springs, they may
isolate vibrations over a large spectrum
of low frequencies. Metal springs transmit
high frequency (from about two hundred
to several thousand c/s) very readily.
Transmission of these frequencies can be
reduced by eliminating direct contact
between the spring and the supporting
structure. Rubber or felt pads may be
inserted between the ends of the spring
and the surfaces to which it is fastened.
2) Rubber in the form of pads may be used
to isolate very effectively engines,
motors, etc. It may be used in compression
or in shear. Some rubber mountings use
rubber-in-shear as the primary elastic
elements and rubber-in-compression as
a secondary element which furnishes
snubbing action if the mounting is
subjected to an overload.
3) Felt or cork or both may be used as
resilient mats or pads under machine
bases. The load per unit area shall be
chosen to produce enough deflection for
the isolation required; and shall be such
that at this deflection, it is not loaded
beyond its elastic limit.
b) Position of Isolator — The normal position
of the isolators is between the machine and
its foundation. However, if the forcing
frequency of the machine is low (less than
10 H ) and vibration isolators with the
requisite deflection for this location are not
available, the machine may be bolted directly
to an independent heavy inertia concrete base
and the available vibration isolators used
below the concrete base.
1) Large press and drop hammers which
create serious impact vibration in heavy
machine shops may be mounted rigidly
on very massive blocks of concrete
having weights several times greater than
the weights of the supported machines.
The inertia blocks may, in turn, be
isolated from the building structure by
large wooden blocks and with thick pads
of cork.
2) In critical installations (see Note), attempt
should be made to locate the resilient
mounts in a plane which contains
the centre of gravity of the mounted
assembly. It is also preferable to locate
the mounts laterally as far away as
possible from the centre of the machine.
NOTE — Critical installations are those
installations where transmission of vibration from
these installations will seriously hamper the
normal working.
3) Rigid mechanical ties between vibrating
machine and building structure, short-
circuit or reduce the effectiveness of
isolators. Loose and flexible connections
should be inserted in all pipes and
conduits leading from the vibrating
machine. Where flexible connections are
impracticable, bends should be inserted
into the pipe6 or the pipes themselves
should be supported on vibration mounts
for a considerable distance from the
source.
4) Flexibility of foundation — The effect
of flexibility of the foundation on
the isolator transmissibility shall be
considered in the selection of practical
vibration isolating mountings. The
simplified vibration isolation theory
assumes a completely rigid foundation.
However, in practice, this can never be
24
NATIONAL BUILDING CODE OF INDIA
achieved. The foundation is never
actually completely rigid. Generally, the
relatively low stiffness of the isolation
system permits the assumption of the
foundation to be rigid. However, if the
stiffness of the isolator is allowed to
become comparable to the foundation
stiffness (or greater), the deflection of
the isolator will become smaller and
the foundation will also deflect with
increased transmissibility and decreased
isolator efficiency. In a dynamic sense,
supporting foundation or floors should
have natural frequency as high and be as
stiff as possible compared to the system
being isolated. Good design practice
requires that the isolators should be
designed assuming a rigid foundation
with the stipulation that the selected
machine isolation system frequency
should be well below the foundation
frequency. This point should specially be
kept in mind when installing machines
at upper levels in buildings because
supported slabs generally have lower
natural frequencies (low stiffness) than
slabs on grade in basement or ground
floor locations.
10.4.4 Noise Reduction by Enclosures and Barriers
10.4.4.1 Enclosures
Air-borne noise generated by a machine may be
reduced by placing the machine in an enclosure or
behind a barrier. The enclosure may be in the form of
close-fitting acoustic box around the machine such that
the operator performs his normal work outside the box
and thus is not subjected to the high noise levels of the
machine. The enclosure may be made of sheet metal
lined inside with an acoustical material.
Where size of the machine, working area and the
operation do not permit close-fitting enclosures, the
machine may be housed in a room of its own. The
inside of the enclosure should be lined with sound-
absorbing materials to reduce the noise level of the
contained sound. The bounding walls of the enclosures
shall also have adequate transmission loss to provide
desired insertion loss.
10.4.4.2 Barriers
A partial reduction of noise in certain directions may
be obtained by 'barriers' or partial enclosures or partial
height walls. Two-sided or three-sided barrier, with or
without a top and invariably covered on the machine
side with acoustic absorption material should face a
wall covered with sound-absorbing material. If the top
of the enclosure is open, the reduction may be increased
by placing sound-absorbing material on the ceiling
overhead.
10.4.5 Acoustical Absorption Devices
10.4.5.1 Acoustical treatment of ceilings and side
walls
In order to reduce the general reverberant noise level
in machine shops, acoustical material may be placed
on the ceiling and side walls. With this treatment 3 to
6 dB reduction of middle and high frequency noise
may be achieved. While the noise level at the source,
affecting the operator, may not be reduced materially,
the treatment would bring down the general noise level
away from the source in reverberant field.
10.4.5.2 Functional sound absorbers
For efficient noise reduction 'functional sound
absorbers' may be clustered as near the machines as
possible. These units may be suspended and distributed
in any pattern to obtain lower noise levels within the
machine shop. Compared on the basis of equal total
exposed surface areas, functional sound absorbers have
higher noise reduction coefficients (NRC) than
conventional acoustical materials placed directly on
ceilings and walls.
11 LABORATORIES AND TEST HOUSES
11.1 Sources of Noise
11.1.1 Outdoor Noise
In a test house or laboratory, where research workers
and scientists are engaged in performing sophisticated
experiments, the external noise is mostly contributed
by noise emitting buildings (workshops, machine
rooms), airports, railway stations and general traffic
noises. The outdoor sources of noise in a college
laboratory include noises produced in a playground as
well.
11.1.2 Indoor Noise
The following sources mainly contribute to indoor
noises in research institutions/college laboratories:
a) Workshops, machine rooms, cafeteria, etc;
b) Air-conditioning and exhaust fans;
c) Noise produced within the test house or
laboratory while performing experiments;
and
d) Typing or other machine noises, telephone
service, lift, sanitary services, etc.
11.2 Recommendations
11.2.1 Site Planning
While planning for a laboratory or test house, care
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
25
should be taken in the design that no noise emitting
installations should exist in its neighbourhood.
However, where outdoor noises exist, such as from
local factory, heavy traffic airports, railway lines, sport
grounds or busy markets, buildings should be kept as
far away as possible from the source of noise.
11.2.1.1 The window and door openings towards the
noise sources should be minimum. Minimum amount
of glazing should be placed on walls directly facing
the noise sources.
11.2.2 Internal Planning
11.2.2.1 Noisy places should be kept separate from
the quiet ones. The location of laboratories or test
houses should be so chosen that it is cut off from the
noisy zones. Where there are offices attached to a
laboratory, provision should be made to treat the offices
and to use acoustical partitions, to achieve a sound
isolation D of at least 35 dB.
w
11.2.2.2 In a laboratory, mostly hard reflecting
surfaces and bare furnishings are found, which
produce very reverberant conditions. The noise
condition still deteriorates when noise producing
instruments are switched on or a heavy object is
dropped on the floor. Under these conditions, sound
absorbing treatment of the space is very essential.
Sound absorbing ceilings are recommended to deaden
such noises. Rubber buffers may also be fitted to the
legs of furniture.
1 1 .2.2.3 In large span laboratories or test houses where
scientists and researchers are engaged in work and/or
simultaneously busy in calculations or desk work
requiring high degree of mental concentration, use of
sound absorbing screens is recommended.
11.2.2.4 Noise reduction between the test house or
laboratory and corridors or general circulation space
should be well kept in mind and due care should be
taken of the type of doors and the manner of their
fittings etc. Transmission of noise through service
ducts, pipes, lifts and staircases should also be guarded.
Telephones should preferably be placed in a separate
small enclosure or acoustically efficient telephone
booth.
11.2.2.5 To isolate a laboratory or a test house from
structure borne noises originating from upper floor,
sandwich type floor construction is recommended.
11.2.2.6 Wherever the provision of double glazed
windows is necessary to reduce the heat losses, care
should be taken to provide sealed double windows
rather than double glazing in a single window.
NOTE — Double glazed windows for sound insulation should
have a minimum gap of 100 mm between the two glasses.
12 MISCELLANEOUS BUILDINGS
12.1 Law Courts and Council Chambers
It is important that law courts and council chambers
be protected from the intrusion of outdoor noise and
from indoor noise arising both from ancillary offices
and circulation spaces. The general recommendations
on site planning given in 3 apply to law courts and
municipal buildings, but in the larger buildings at least,
further protection against outdoor noise can be obtained
by planning offices and other rooms around the court
rooms or chambers, and separating the offices from
the central rooms by means of corridors. This
arrangement is usually convenient to the function of
the buildings.
12.1.1 The wall between the corridors and the central
rooms should have a sound reduction index, R of not
less than 50 dB (for example 230 mm brick) to insulate
against air-borne noise in the corridors. Entrances from
halls or corridors into court rooms or council chambers
should be through baffle lobbies with two sets of quiet
action doors. Sound absorbing treatment on ceilings
and upper parts or walls or entrance lobbies is
recommended.
12.1.2 The whole of the floor of the court room or
chamber including steps and seating areas set aside
for the public should have a resilient floor finish to
reduce the noise of footsteps and shuffling of feet. Any
tip-up seats should be quiet in action.
12.1.3 Sound absorbing treatment applied for acoustic
purposes serves also to reduce the build-up of noise
within the room and, part of the treatment should be
applied in a band to the perimeter of the ceiling to
absorb intruding outdoor noise. It is often desirable to
keep the centre part of the ceiling free of absorbent
material for acoustic reasons.
12.2 Libraries, Museums and Art Galleries
Quiet conditions for reading and study are essential
in these types of buildings and, since their occupancy
is not noise producing, intruding noise is more
noticeable and distracting. Every opportunity
therefore should be taken to plan for noise defence,
both in respect of siting of the building and internal
planning. When possible, stack rooms, store rooms
and administrative offices should be planned to screen
reading rooms, print rooms and lecture rooms from
noise sources. In public libraries, the reference library
and lecture rooms should receive first consideration;
the lending library, newspaper and periodical rooms
have a higher background noise and are secondary in
importance.
12.2.1 In large libraries, museums and art galleries
26
NATIONAL BUILDING CODE OF INDIA
echoes from lofty, large domed or concave ceilings
are often a nuisance. Small noises such as footsteps,
coughs, chair scraping and closing of books are
reinforced by reverberation, and concave surfaces even
when treated with a sound absorbent may focus these
noises. Treated flat ceilings, if not too high, obviate
these troubles. Books on shelves in libraries constitute
a valuable wall absorbent.
12.2.2 Floor finishes are important. The impact noise
of footsteps on marble, terrazzo or wood block
flooring, and especially on hardwood strip and batten
flooring, can be disturbing both within the room in
which the noise is generated and the rooms below. On
solid floors, resilient floor finishes, such as rubber, cork
and linoleum on an underlay, are highly desirable. In
the children's sections of libraries and museums they
are essential. In existing buildings, rubber linoleum or
vinyl asbestos tiles laid over the floor in the traffic
areas are often a solution to the problem.
12.2.3 Reference libraries in universities, research
establishments, office buildings and science buildings
having machines and testing benches, should be
planned in a quiet part of the building. Walls
enclosing the library should normally have a sound
reduction index, /? w of not less than 50 dB (for
example 230 mm brick) and baffle lobbies should be
planned between the library and halls and corridors.
Walls facing on to corridors or other noisy areas
should not have fanlights unless they are double
glazed and non-operable.
12.3 Auditoria and Theatres
The sources of noise that have to be considered in
concert halls, opera house, theatres and similar
auditorium buildings are as follows:
a) Outdoor noise entering through walls, roofs,
doors, windows or ventilation openings;
b) Noise from any other hall in the same
building, especially if let out separately for
revenue;
c) Noise from foyers, service rooms and other
ancillary rooms, particularly rehearsal rooms;
and
d) Noise from air conditioning plant, etc, and
the cross-transmission of other internal noises
via ventilating duct system.
12.3.1 Because of greatly increased outdoor noise, all
auditorium buildings now need more care in siting than
formerly. For listening to speech or music, a very low
background noise level is desirable; in concert halls
especially the quietest possible conditions should be
provided because the pauses and moments of silence
which are an essential element of music cannot
otherwise be given full value. Therefore, sites at cross-
roads or close to steel railway bridges, religious places
or near churches where bell ringing is practiced, should
be avoided unless very high standards of structural
sound insulation are contemplated. Sites adjoining
underground railways may also prove unsatisfactory
at basement levels owing to low-pitched noise or
rumble transmitted through the ground; special
isolation measure need to be adopted for isolating large
buildings from ground vibration of this sort.
12.3.2 Whenever possible, for concert halls and
theatres on city sites a noise survey of the site should
be made; a suitable sound reduction value for the
structure of the building can then be chosen so as to
keep down to certain maximum noise levels within the
auditorium. The maximum octave-band sound pressure
levels (SPL) recommended are given in Table 8.
Table 8 Maximum Sound Pressure Levels Due
to External and Mechanical Equipment
Noise in Auditoria (dB)
(Clause 12.3.2)
Type of
Auditorium
Concert Halls
[dB(A)-25]
Centre Frequency (Hz)
63 125 250 500 1000 2000 4000 8000
51 39 31 24 20 17 14 13
Drama Theatres 55 44 35 29
and Cinemas
[dB(A)-30]
25 22 20
18
12.3.3 The minimum standard of sound reduction
index, /? w likely to be required for the envelope of an
auditorium in a city to protect it against external noise
is of the order of 65 dB for a concert hall or 55-60 dB
for a theatre. This reduction should be provided on all
sides, but it would be reasonable to make the R w for
the roof 5 to 1 dB less provided the building is not
unduly exposed to noise from aircraft in flight.
Surrounding the auditorium with ancillary rooms and
foyers is an obvious and invaluable planning method
of obtaining the required insulation against outdoor
noise.
12.3.4 Ventilation intakes and returns are vulnerable
features in the defence against external noise. They
should be positioned so as to avoid exposure to noise,
and in addition sufficient length of both inlet and outlet
ducts should be provided with carefully designed
silencers. The ventilation system should also be
designed to avoid transmitting or adding to internal
noise.
12.3.5 The most serious internal noise problem arises
when there are two halls meant for separate use in the
same building, especially if one of them is a concert
hall. The latter is a very loud potential source of noise
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
27
and requires a high standard of protection against
extraneous noise. In these circumstances it is doubtful
whether a 'single' wail can be adequate for insulating
the two halls unless it is designed with a wide unbridged
cavity. Separation by planning is preferable.
12.3.6 Other sources of internal noise are rehearsal
rooms, scenery bays and workshops, stages of other
halls where rehearsals or erection of stage sets might
be in progress and foyers and bars where loud
conversation might occur. The insulation of the internal
walls should be adequate to protect the auditorium from
these noise sources and the insulation should not be
by-passed by openings, doorways, etc. The general
noise due to banging of doors also needs to be taken
care of; soft sealing materials should be provided for
all doors to ensure quiet closing.
12.3.7 For detailed acoustical design of auditoria and
conference halls reference may be made to good
practice [8-4(3)].
12.4 Cinemas
The main objective of the design should be to control
noise from adjacent screens, the projection area, the
foyer, and outside the cinema. The first of these,
controlling noise from adjacent screens, is likely to be
the most difficult with modern digital sound systems.
As most cinemas are air conditioned, there will be some
noise from services. To ensure reasonable listening
conditions, this should be limited to 30 dBA. This will
provide some masking of the noise from adjacent
screens, but a high performance partition will still be
essential. Masonry or lightweight construction may be
used, and a typical performance specification for a
lightweight wall separating two screens is given
in Table 9. Cinema design, however, normally requires
specialist acoustic advice.
Table 9 Typical Sound Insulation Specification
for Wall Separating Two Cinema Screens
(Clause 12 A)
Octave Band
Hz
Sound Reduction Index
/?, dB
63
125
250
500
1000
2 000
4 000
8 000
38
44
50
61
57
58
57
55
13 NOISE FROM BUILDING SERVICES
13.1 Mechanical, electrical, air conditioning, heating
and mechanical ventilation, and other services are
provided in almost all large buildings excluding
residential, commercial and industrial buildings. Noise
control measures should be incorporated during the
design and installation of such services to adhere to
the recommended outdoor and indoor noise criteria for
the kind of occupancy. For detailed design of noise
control for services, specialist advice should be sought.
Some basic design techniques for noise control in air
conditioning, heating and mechanical ventilation
system are given in Annex G.
13.2 Control of noise from mechanical equipments
can also be done by specifying noise control
requirements while purchasing the equipments (see
Annex H).
ANNEX A
(Clause 2.4)
NOISE CALCULATIONS
A-l GENERAL
Some of the simpler types of noise calculation are
described in this Annex.
A-2 ADDITION OF TWO NOISE LEVELS
To determine the combined sound pressure level (L c )
resulting from the sound pressure levels of two or more
noise sources (L p L 2 , etc), it is necessary to calculate
and add the mean square values of their individual
sound pressures and then convert this back to a sound
pressure level. This can be done using the following
formula:
L c = 1010g JO (10 L1/i0 + 10 L2/l0 )
As the individual sound pressure levels are logarithms
of the mean square sound pressures, they cannot
simply be added arithmetically. Figure 3 shows a
graphical method for adding the sound pressure levels
from two independent sources to obtain the combined
sound pressure level at a particular place. This graph
may also be used for multiple sources by combining
sources two at a time to produce virtual sources that
can then be combined. The most accurate approach
is to start with the lowest levels and work towards
the highest.
28
NATIONAL BUILDING CODE OF INDIA
j.u ^
1.0 -•
n.
,
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
DIFFERENCE BETWEEN LEVELS (IN dB)
Fig. 3 The Addition of Two Noise Levels
The graph should be used with caution where the noise
sources are not independent. For example, the sound
pressure level from two large transformers fed with
currents in phase will be very sensitive to the receiving
position. This is because the effect of the constructive
and destructive interference of the sounds from the two
sources is very dependent on position.
A3 SUBTRACTION OF TWO NOISE LEVELS
When measuring noise from a source, the true noise
level of the source alone will be less than that shown
by the meter if the level of extraneous noise is less
than about it) dB below the total noise level. An
estimate of the true source level can be obtained from
Fie. 4.
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A-4 NON-UNIFORM COMPOSITE PARTITIONS
Figure 5 how to calculate the overall sound insulation
of a composite partition consisting of two parts having
different sound — insulating properties, for example
a window in a wail. It may also be used to give an
indication of the effect of gaps or holes in a partition
by assigning a sound insulation value of dB to the
aperture.
A-5 A-WEIGHTING CALCULATIONS
The equivalent A- weighted level is often required when
data on a noise source is available as a set of octave
band or one-third octave band levels. The conversion
can be done manually, using the standard A- weighting
values (Table 10) and the graph for combining levels
(Fig s 3). For all but the simplest situations it is more
convenient to use a computer spreadsheet to do the
conversion.
Table 10 Standard A-Weighting Values (dB)
Third Octave
A-Weighting
Third Octave
A-Weighting
Band Center
Band Centre
Frequency
Frequency
Hz
dB
Hz
dB
0)
(2)
(3)
(4)
10
-70.4
500
-3.2
12.5
-63.4
630
-1.9
16
-56.7
800
-0,8
20
-50.5
1000
25
-44,7
1250
0.6
31.5
-39.4
1600
1.0
40
-34.6
2 000
1.2
50
-30.2
2 500
1.3
63
-26.2
3 150
1.2
80
-22.5
4000
1.0
100
-19.1
5000
0.6
125
-16.1
6 300
-0.1
160
-13.4
8 000
-1.1
200
-10.9
10 000
-2.5
250
-8.6
12 500
-4.3
315
-6.6
16 000
-6.6
400
-4.8
20 000
9.3
DIFFERENCE BETWEEN TOTAL AND EXTRANEOUS
NOISE LEVEL (IN dB)
Fig. 4 Subtraction of Noise Levels
A-6 REVERBERATION TIME CALCULATION
An estimate of the reverberation time (7) of a room
can be obtained from the Sabine formula:
(0.1610
where
V = is the volume of the room in cubic metres
(m 3 );
A. = is the equivalent sound absorbing area in the
room in square metres (m 2 ).
The A. are the absorbing areas of each surface, or other
permanent fixture in the room. Each A { is determined
by multiplying the area of that surface in square
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
29
1:1000000-
1:500000
1:250000
1:125000
1:64000
1:32000
z
o
1:16000
§
1:8000
3
CO
1:4000
LU
1:2000
X
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1:1000
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1:500
1:250
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1:125
LU
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1:64
1:32
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1:8
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1:4
1:2
1;1
2:1
4:1
8:1
10 15 20 25 30 35 40 45 50 55 60
LOSS OF INSULATION: DEDUCT FROM
HIGHER INSULATION (IN dB)
Fig. 5 Sound Insulation of Non-Uniform Partitions
metres (m 2 ) by its absorption coefficient a si . The
surface of each significant fixture or feature of the
room should be considered as well as the walls, ceiling
and floor.
The total absorption is obtained by summing the
individual A. values. As the values of a si are frequency
dependent, this calculation should be repeated for each
octave band of interest.
An allowance should also be made for people and
furnishings in the room.
30
NATIONAL BUILDING CODE OF INDIA
ANNEX B
(Clauses 2.24, 2.38, 2.41, 2.50, 2.51, 2.52 and 2.53)
SPECIFICATION OF SOUND INSULATION
B-l GENERAL
Sound insulating elements work mainly by reflecting
sound energy back into the source room, not by
absorbing it. The methods of measurement and the
terms used are described in B-2 to B-4.
B-2 INSULATION AGAINST AIR-BORNE SOUND
As per the standard tests, the insulation between a pair
of rooms is measured either in third octave bands
having centre frequencies which cover at least the range
100 Hz to 3 150 Hz, or in octave bands which cover at
least the range 125 to 2 000 Hz. The noise is produced
by a loudspeaker in one of the rooms (called the source
room) and at each frequency the average noise levels
are measured in the source room (L s ) and in the
adjacent receiving room (L R ). The difference between
these two levels (D) is a measure of the sound insulation
between the rooms regardless of the transmission
path(s) the sound energy followed to travel between
the rooms. The equation is as follows:
D = L S -L R
The actual level in the receiving room depends on:
a) the sound insulation of the separating wall or
floor,
b) the area of the separating wall or floor;
c) the volume of the receiving room;
d) the amount of flanking transmission (that is
the importance of transmission paths other
than the separating wall or floor); and
e) the amount of absorbing material (for example
furniture) in the receiving room.
For field measurements, apart from the amount of
absorption, these factors are a property of the building
and should be taken into account by the measurement
procedure. As the amount of absorbing material (for
example soft furniture) in the room at the time of
measurement is arbitrary, it should be allowed for
separately. This is achieved by measuring the
reverberation time (T) of the room in seconds (s),
which is a measure of how long it takes a sound to die
away after the source has been switched off. As the
sound energy is dissipated as heat in the absorbing
material (T), it is related to the total amount of
absorption in the room. The receiving room level may
then be corrected to the level it would be if the room
had a standard reverberation time (J ) which is typical
of furnished rooms, and is taken to be 0.5 s. The
corrected level difference is known as the standardized
level difference, which has the symbol D nT and is
calculated using the following equation:
D aT =L s -L R+ 10 \og w (TfT )
For laboratory measurements, the insulation of the
separating wall or floor being tested is required in a
way which is independent of the actual measuring
laboratory. For this reason, laboratories are designed
to have minimal flanking transmission and a different
correction is applied to account for the other factors.
This correction is 10 log 10 (S/A).
where
S
A
- is the common area of the separating wall
or floor in square metres (m 2 ); and
= is the equivalent absorption area in the
receiving room in square metres (m 2 ).
The laboratory corrected level difference at each
frequency is known as the sound reduction index,
which has the symbol R and is calculated using the
following equation:
R =L s -L R +101og 10 OS/A)
If the test wall or floor is mounted in a realistic way in
the laboratory and flanking transmission will be low
in the field, the sound reduction index may be used to
predict its performance in the field. The relation
between D nT and RisD nT =R- 10 log 10 (3S/V)
where
S = is the area of the separating wall or floor in
the field in square metres (m 2 ); and
V = is the volume of the receiving room in the
field in cubic metres (m 3 ).
This equation shows that if the source and receiving
rooms have different volumes, D nT will depend on
which is used as the source rotfm; using the larger room
as the source room will give lower value.
B-3 INSULATION AGAINST IMPACT SOUND
The procedure to measure the impact insulation of
floors is rather different. Instead of a loudspeaker, a
machine containing five small hammers is placed on
the floor. While the hammers strike the floor at a rate
of 10 blows a second, the resulting noise level (L.) is
measured in the receiving room below at each of the
same frequency bands used for airborne insulation. In
the field, the receiving room levels are again
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
31
'corrected' to a standard reverberation time (T o ) of
0.5 s to give the standardized impact sound pressure
level, L nT , which is calculated as follows:
L BT =^-1010^(77?;)
In the laboratory, the noise level depends mainly on
the characteristics of the floor being tested and the
amount of absorption (A m 2 ) in the laboratory. It is
therefore appropriate to correct the noise level to a
standard area of absorption. The area used is 10 m 2 .
The resulting normalized impact sound pressure
level is given the symbol L n and calculated as
follows:
L n = L i+ 101og 10 (A/10)
B-4 RATING SOUND INSULATION
Measurements of insulation against both air-borne and
impact sound yield values in a number of frequency
bands. To make this information more manageable,
rating methods such as those in accordance with
[8-4(1)] are used to reduce the frequency band values
to single figure ratings. These single figure ratings
should be good predictors of subjective assessments
of insulation. However, this is not always the case and
it is prudent to examine the full measurement data in
critical situations. The impact insulation measured on
a floor with a carpet is likely to be overestimated by
this method.
The more common indices used to describe sound
insulation are summarized in Table 1 1 .
Table 11 Common Indices Used to Describe
Air-borne and Impact Sound Insulation
(Clause B-4)
Air-borne
(A)
Impact
CO
Lab
(L)
Field
(/0
Measured \
• A -
Name
r alues
Single Number
Quantity
Symbo]
I Name
Symbol
(1)
(2)
(3)
(4)
(5)
(6)
A
F
Standardized
level
difference
z> nT
Weighted
standardized
level
difference
AiT.w
A
L
Sound
reduction
index
R
Weighted
sound
reduction
index
Aw
I
F
Standardized
impact sound
pressure level
L nT
Weighted
standardized
impact sound
pressure level
L nT, w
I
L
Normalized
impact sound
pressure level
L\
Weighted
normalized
impact sound
pressure level
Li n, w
ANNEX C
(Clause 2.22)
NOISE RATING
C-l Noise rating (NR) is a graphical method for
assigning a single number rating to a noise spectrum.
It can be used to specify the maximum acceptable level
in each octave band of a frequency spectrum, or to
assess the acceptability of a noise spectrum for a
particular application. The method was originally
proposed for use in assessing environmental noise, but
was later also found suitable for describing noise from
mechanical ventilation systems in buildings. To make
a rating, the noise spectrum is superposed on a family
of NR contours; the NR of the spectrum corresponds
to the value of the first NR contour that is entirely above
the spectrum. The data for drawing NR contours (from
NR to NR 75) is given in Table 12 for the frequency
range 31.5 Hz to 8 kHz.
C-2 For computational methods the curves are defined
by the equation:
L = a + bN
where
L = is the octave band sound pressure
level corresponding to NR level N;
and
a and b - are constants for each frequency band,
as given in Table 13.
NOTE — NR values can not be converted directly to
dBA values but the following approximate relationship ,
applies:
NR = dBA -6
C-3 Although the NR system is currently the preferred
method for rating noise from mechanical ventilation
system, other methods which are more sensitive to
noise at low frequencies are available, but they are not
yet widely accepted. Low frequency noise may be
disturbing or fatiguing to occupants, but may not have
much effect on the dBA or NR value.
32
NATIONAL BUILDING CODE OF INDIA
Table 12 Noise Rating Values
(Clause C-l)
Table 13 Values of a and b
(Clause C-2)
Octave Band Centre Frequency, H z
Noise
Rating
Sound Pressure Levels dB« 20uPa
Octave Band Centre
a
b
Frequency
* —
31.5
63
125
250
500
1000
2000
4000
8 000
Hz
(1)
(2)
106
(3)
95
(4)
87
(5)
82
(6)
78
(7)
75
(8)
73
(9)
71
(10)
69
(1)
(2)
(3)
NR75
3L5
55.4
0.681
NR70
103
91
83
77
73
70
68
66
64
63
35.4
0.790
NR65
100
87
79
72
68
65
62
61
59
NR60
96
83
74
68
63
60
57
55
54
125
22.0
0.870
NR55
93
79
70
63
58
55
52
50
49
250
12.0
0.930
NR50
89
75
66
59
53
50
47
45
43
500
4.2
0.980
NR45
NR40
86
83
71
67
61
57
54
49
48
44
45
40
42
37
40
35
38
33
1000
0.0
1.000
NR35
79
63
52
45
39
35
32
30
28
2000
-3.5
1.015
NR30
76
59
48
40
34
30
27
25
23
4000
-6.1
1.025
NR25
NR20
72
69
66
55
51
47
44
39
35
35
31
26
29
24
19
25
20
15
22
17
12
20
14
9
18
13
7
8000
-8.0
1.030
NR15
NR10
62
43
31
21
15
10
7
4
2
NR5
59
39
26
17
10
5
2
-1
-3
NRO
55
35
22
12
5
-4
-6
-8
ANNEX D
(Clause 3.3)
OUTDOOR NOISE REGULATIONS IN INDIA
D-l Government notifications are issued from time-
to-time on the allowable ambient noise levels in general
and specifically in different zones of various
metropolitan cities of India.
D-2 Noise regulations and notifications are also issued
from time-to-time specifying the maximum permissible
sound levels from equipments commonly used in and
around the residential areas and around sensitive
buildings, specifically with regard to noise levels from
electricity generating sets, construction equipment and
HVAC utility equipment installed outdoors.
D-3 These regulations should be referred to by the
designer for the design of measures for control of
external noise.
ANNEX E
(Clauses 3.8 and 4.5)
SPECIAL PROBLEMS REQUIRING EXPERT ADVICE
El GENERAL
Certain design problems require reliable advice of a
kind which is not easy to find in published material.
The advice of an expert should be sought for these
kinds of problems, some examples of which are given
in E-2 to E-9.
E-2 ACOUSTIC TEST ROOMS
The design of rooms in which acoustic measurements
are carried out, such as reverberation chambers, free-
field anechoic rooms and audiometric test rooms,
usually requires the advice of an expert.
E-3 PERFORMING SPACES
The design of theatres, opera houses, concert halls
and similar performing spaces usually requires
expertise in room acoustics and noise control. The
intrusion of quite low levels of noise may seriously
interfere with the enjoyment of the performance and
distract the performers. The requirements for low
noise levels often mean that more room has to be
allocated for low velocity ventilation ductwork and
the impact on the design of the ventilation system is
often substantial.
E-4 BROADCASTING
STUDIOS
AND RECORDING
Broadcasting and recording studios have requirements
similar to those of performing spaces. For some
infrequent intrusive noises, the requirements are
sometimes relaxed on the grounds that a re-take of a
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
33
recording can be done, but this can result in higher
operating costs.
E-5 AIRCRAFT NOISE
As there are many variables affecting the level of
aircraft noise heard on the ground, expert advice is
almost always required. Contours of daytime L Aeq T
levels are available from most major airports. Where
measurements of facade insulation are necessary a
standard test method may be referred.
E-6 GROUND-BORNE NOISE
Projects involving ground-borne noise from underground
trains usually require expert advice.
E-7 LOW-FREQUENCY NOISE
Projects involving low-frequency noise usually require
expert advice as accurate measurement is difficult and
there is a shortage of reliable data below 100 Hz.
E-8 ACTIVE NOISE CONTROL
Active noise control is the reduction of noise by
cancellation with a similar noise (anti-noise) generated
by electro-acoustic means. The technique is still under
development, but commercial systems are available
which successfully reduce low frequency noise from
mechanical ventilation systems.
E-9 NOISE SURVEYS
Noise surveys are carried out for a variety of reasons,
for example:
a) before construction, to establish the existing
noise climate at the site of a proposed
development where reliable prediction is
impracticable, as an aid to the design of the
building envelope, either to protect against
external noise or contain internally produced
noise;
b) during construction, to monitor noise from
building activity, either to assess the likely
nuisance to the local community or the risk
of hearing damage to the work force;
c) at the end of a building contract to check the
insulation of the building envelope, or the
noise levels produced by the services;
d) as part of a planning requirement; and
e) to provide objective evidence to support or
defend a legal action.
The expense of carrying out a comprehensive noise
survey of any kind is likely to be high, so the cost-
effectiveness of a full or partial survey should be
weighed against alternatives such as prediction. A
survey will generally be more accurate and can take
account of factors such as prevailing wind conditions.
ANNEX F
(Clause 4.4)
AIR-BORNE AND IMPACT SOUND INSULATION
F-l GENERAL
Air-borne sound refers to sources which produce sound
by directly setting the air around them into vibration.
Impact sound refers to sources which produce sound
by impulsive mechanical excitation of part of a building
(for example by footsteps, electric light switches,
slamming doors). Many sources of impact sound also
produce significant levels of airborne sound. The term
structure-borne sound has no very precise meaning as
the structure can be excited by both airborne and impact
sources; it is often used to refer to sound that travels
for long distances via the structure, especially in
connection with vibrating machinery linked directly
to the structure.
F-2 DIRECT AND INDIRECT TRANSMISSION
Figure 6 shows diagrammatically a pair of rooms in a
house where the construction consists of solid walls,
etc bonded together. Sound travelling from room 1 to
room 2 may travel via the direct path a-a and by the
many indirect, or flanking, paths shown. The term
flanking transmission is usually used to mean
transmission paths involving the structure, while the
term indirect transmission includes flanking paths and
airborne paths through gaps and ducts, etc. The indirect
paths may limit the sound insulation attainable no
matter how much the direct sound is reduced by the
separating wall or floor. The indirect transmission can
be reduced by measures such as the following:
a) Increasing the mass of the flanking walls;
b) Increasing the mass of the partition and
bonding it to the flanking walls;
c) Introducing discontinuities in the indirect
paths;
d) Erecting independent wall linings adjacent to
the flanking walls to prevent energy entering
the flanking construction; and
e) Sealing any air gaps and paths through ducts.
34
NATIONAL BUILDING CODE OF INDIA
R00M1
ROOM 2
^;/;/;/;;//>;;;;;;;;;/a
ELEVATION
ROOM1-
!
V////A U'c++t
d c
d c
Tzzzzz£^m
I
/
z^z^VH ^^7 777
b d
■*-c
-— a
b d
LI
*?&.>. >.>M
ROOM 2
'2Z2>
PLAN
Fig. 6 Transmission Paths (Via the Structure) of Noise Originating
in Room 1 (Diagrammatic)
Figure 7 shows a number of indirect paths that have measurements to those likely to be obtained in the
been found in offices. field.
It is important to remember that standard test F-3 AIR-BORNE SOUND INSULATION
laboratories are designed to minimize transmission
by all paths other than the direct path. This makes
it difficult to relate the results of laboratory The sound insulation of structural elements such as
F-3.1 General
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
35
2
3
>
r
w
P
o
z
o
o
o
a
o
5
1 LIGHTWEIGHT PANELS ABOVE DOORS
2 DOORS
3 AIR LEAKS THROUGH GAPS, CRACKS OR HOLES
4 SOUND TRANSMISSION VIA SUSPENDED CEILINGS/PARTITIONS
5 COMMON VENTILATION SYSTEMS WITHOUT SILENCf RS
6 COMMON FLOOR DUCT
7 ELECTRICAL OUTLETS AND SERVICE PIPES
8 LIGHTWEIGHT MULLIONS OR MULLION/PARTITION CLOSERS
9 CONTINUOUS SILL LINE HEATING
10 PARTITION PERFORMANCE
11 APPLIANCES
12 CONTINUOUS LIGHTING FITTINGS
Fig. 7 Indirect Sound Leakage Paths
wans ana uoors aiways varies witn frequency, irie
msuiatiOij rising in general as Uie ucquency rises.
F-3.2 Terminology
Results from field measurements are usually
cApicsscu in icinia ui luc wtigmcu Mmiuaiuj^cu icvu
univivuv^, vYiinv^ lauuiuiui) ijljlv^<*oujlv^hiv^ii»-o a±\s U3uau)
PYnrp«cpH in tprmc r\f thf cminH r^Hnr'tirm inH^v Tn
V/lJJiVUUVU 111 tWl Alio VI HIV UVM11M 1 VWUVUV/ll lllMViA. All
the absence of significant flanking transmission
the numerical difference between the weighted
standardized level difference and the sound reduction
index of a wail or floor is usually small for furnished
rooms in dwellings, and so either quantity may be
used in considering principles; for this purpose it is,
therefore, convenient to use the general term
insulation.
An approximate empirical relationship has been
established between sound insulation and mass for
single leaf constructions as shown in Fig. 8. This so
called 'mass law' gives a useful first approximation to
the behaviour of a single sheet or plate. In practice,
the sound insulation predicted by the mass law may
not be attained because of factors such as the
iwi sjjttinc uiaLciiais \aiy aiuunu liic vaiuc given uy
vuv iiiciiu itiw lv^iauuncuij^/, unu ow mvaouivu uaiu aimuiu
hf iicprl u/hf»n n\;nil^h1f» TaMf» 1 A cri\/f»e a liete of
«^ V k"L5\^U TT 11 VI 1 fc*T H.HW.U IV. -I M-1_^1V A I tlTVU U HkJtU VI
materials and indicates the sound insulation of a single,
imperforate sheet when fixed to a suitable wood or
metal framework. These values are useful, for example
when assessing existing structures.
lauie 11 sound insulation or linpenoraie
(Clause h-3.3)
Material
Surface
Typical Weighted
Mass
Sound Reduction
index, R w
—&■ —
dB
0)
(2)
(3)
d rniii giass Succt
/.u
12.5 mm plasterboard
10.5
31
18 mm wood particle board
8.0
27
19 mmpJywood
3.0
24
\f\ mm TvUfw/rin/H
45
24
1 mm steel sheet
11.0
29
6 mm hardboard
5.0
25
12 mm wood fibre insulation
4.0
24
board
13 mm mineral fibre board
4.0
24
50 mm wood-wool screeded
35.0
33
The coincidence effect occurs when the wavelength
of the wave impressed on the panel by the incident
sound wave is close to the wavelength of free bending
waves in the panel. The effect of coincidence is to
lower the sound insulation of a construction by as
™ — i 1 a at> u~i *u~ i 1 *~ j .c :*„ „
inu^ii <ia iu ud uciuvv liic icvci cajjc^icu nuiii us mass
t^Nia-r- tin-It i-fiii Airar o 1i m-t ta/1 fra/itian^u -#«o*^ rr*a Tl-iia
pvi uiiii aiva \j wi a mimvu iivljuvuvj langv. mv
PAinpiHpnpp <=»ff<=»r*t r>Qn Hp rvrrmrmnr'P'rl «/ith thin
VVJ11IV1UV11VV VI 1 W V Villi Ij" V J^lVlllVUllVVU TT 1111 llllll
liahtweicrht nartitinns rpsultina in loss nf insulation
at middle and high frequencies ; Reducting the
stiffness without a corresponding reduction of mass
can raise the critical frequency above 3 150 Hz, and
so improve the insulation over the important 100 Hz
60
| 50
z
o
1-
ytK
5
"TV
_>
CO
£_
40
r^
2
-i
O
en
35
30
1U
-X-
X
^
X
-y^
/
zX-
/ Rw = 21.65 Igm'- 2.3
y^ m'fr 50kg/m 2
SURFACE MASS, m" (kg/rrf )
Fig. 8 Mass Law Curve
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
37
to 3 150 Hz range. An increase of stiffness will have
the reverse effect.
It is possible to design lightweight stud partitions so
that they perform to their maximum effect in the speech
frequency region between 250 Hz and 2 000 Hz, that
is between the mass-spring-mass and coincidence
regions respectively.
The worst coincidence dips occur in materials such as
plate glass and rigid metal sheets. Heavily damped
materials such as lead sheets are least affected.
F-3.5 Mass-Spring-Mass Frequency
A double leaf wall can perform better than a single
leaf wall of similar mass because the sound has to pass
through two barriers. If the two leaves are not
connected to each other, the insulation values of the
two leaves may be added together. However, in practice
the leaves are often connected by ties or studs, and the
full insulation cannot be achieved. Even where the two
leaves are isolated from each other, the full benefit
can only be obtained above a certain frequency that
depends on the cavity width. This is because the air in
the cavity behaves like a spring connecting the leaves
together, and causes a resonance at the mass-spring-
mass frequency. Below this frequency, the two leaves
behave more like an equivalent single leaf.
Making the cavity width wide can reduce the mass-
spring-mass frequency, as in the case of sound insulating
secondary glazing. The mass-spring-mass frequency
(F () ) may be estimated from the following equation:
F n =59.6.
!l
1 1
— + —
where
m ] and m 2 - the surface masses of the two leaves
in kilograms per square metre
(kg/m 2 ); and
d - the cavity width in metres (m).
F-3.6 Impact Sound Control
A structure that receives an impact or has a vibrating
source in contact with it behaves more like an extension
of the source rather than an intervening element
between source and listener. For this reason, a relatively
small amount of impact energy may produce a loud
sound and, if the structure is continuous, the sound
may travel a long distance. Control is usually obtained
by inserting a resilient surface at the point of contact
with the source (for example laying a carpet on a floor)
or by introducing a structural discontinuity.
Floating floors, which are an example of the latter
approach, are a common method of controlling impact
sound from footsteps. However, it should be noted that
an effective floating floor may result in increased sound
from impacts on the source side of the floor.
The conventional forms of floating floor may be
unsatisfactory if protection against the low-frequency
content of impact noise is required (e.g. a dance floor
over a restaurant).
F-4 AIR-BORNE INSULATION VALUES OF
WALLS AND AIR-BORNE AND IMPACT
INSULATION VALUES OF FLOORS
Table 15 and Table 16 give examples of common types
of wall and floor construction with sound insulation in
the ranges shown. The insulation indices are for field
measurements accessed in accordance with [8-4(5)].
The insulation values given are necessarily approximate
since examples of nominally identical constructions
may show variations of several decibels. All the figures
represent values expected in the field, that is in
actual buildings. Many are based directly on field
measurements, though other (in the absence of
representative field measurements) have been assessed
from laboratory data, with an allowance for typical
flanking conditions in normal buildings. Variation in
the amount of indirect transmission may affect
significantly the insulation between two rooms
separated by a given barrier. For example, the sound
insulation of some types of floor may be reduced by
indirect transmission along the walls supporting them,
particularly if these walls are of lightweight masonry
and carried past the floor.
Table 15 Air-borne Sound Insulation of
Walls and Partitions
(Clause F-4)
Sound
Insulation
D _
nT, w
dB
(1)
Type of Wall or Partition
(2)
26 to 33 a) 1 mm steel sheet panels fixed to steel frame
members to form demountable partition units
50 mm overall thickness. Mineral wool cavity
insulation.
b) Plywood or wood fibre board 12 mm thick nailed
both sides of 50 mm x 50 mm timber framing
members spaced at 400 mm centres.
c) Paper faced strawboard or wood wool 50 mm thick
panels plastered both sides.
d) Chipboard hollow panels 50 mm thick tongued
and grooved edges, hardboard faced. Joints
covered with wood trim.
33 to 37 a) Lightweight masonry blockwork. Plaster or
drylining on at least one side. Overall mass per
unit area not less than 50 kg/m 2 .
b) Laminated plasterboard at least 50 mm thick fixed
to timber perimeter framing, any suitable finish.
Approximate mass per unit area 35 kg/m 2 .
38
NATIONAL BUILDING CODE OF INDIA
Table 15 — Continued
(l)
(2)
c) Timber stud partitions any size timbers greater than
50 mm x 50 mm, 400 mm centers, cross noggins,
9.5 mm plasterboard lining on both sides, any
suitable finish.
d) Metal stud partition, 50 mm studs 600 mm centres,
clad both sides with 12.5 mm plasterboard, joints
filled and perimeters sealed. Approximate mass
per unit area 18 kg/m 2 .
e) 50 mm lightweight masonry blockwork, plastered
both sides to 12 mm thickness or drylined with
9.5 mm plasterboard.
37 to 43 a) Lightweight masonry blockwork, plaster or dry
lining on at least one side. Overall mass per unit
area not less than 75 kg/m 2 .
b) Either 75 mm or 100 mm x 50 mm timber studs
spaced 600 mm apart, 50 mm mineral fibre quilt
in stud cavity. Frame lined on both sides with one
layer 12.5 mm plasterboard. Approximate mass
per unit area 19 kg/m 2 .
43 to 50 a) Masonry wall, joints well filled. Either plaster or
dry lining on both sides. Overall mass per unit
area not less than 150 kg/m 2 .
b) 100 mm metal stud partition, 'C section studs not
greater than 600 mm spacing, not less than
nominal 50 mm web depth. Clad on both sides
with two layers of plasterboard of not less than
22 mm combined thickness. Mineral fibre quilt
hung between studs. Approximate mass per unit
area 35 kg/m 2 .
c) 75 mm x 50 mm timber framing using staged studs
at 300 mm spacing with 25 mm stagger forward
and back. Frame clad with two layers of 12.5 mm
of plasterboard on both sides. Mineral fibre quilt
hung between studs. Approximate mass per unit
area 36 kg/m 2 .
d) 50 mm x 25 mm timber stud partition to form a
25 mm cavity, clad on both sides with minimum
38 mm wood wool slabs having their outer faces
screeded or plastered.
e) Solid autoclaved aerated concrete block 215 mm
thick plaster or dry lined finish on both sides,
blockwork joints well filled. Overall mass per unit
area not less than 160 kg/m 2 .
50 to 54 a) Two separate frames of timber studs not less than
89 mm x 38 mm, or boxed metal studwork with
50 mm minimum web depth. Studs at 600 mm
maximum centres. A 25 mm mineral wool quilt
suspended between frames. Frames spaced to give
a minimum 200 mm overall cavity. Clad on
outside of each frame with a minimum of 30 mm
plasterboard layers (for example 1 9 mm plus
12.5 thickness). Approximate mass per unit area
54 kg/m 2 . 1 )
b) Either in-situ or pre-cast concrete wall panel
not less than 175 mm thick and not less than
415 kg/m 2 . AH joints well filled. 1 )
c) Brick wall nominal 230 mm thickness, weight
(including plaster) not less than 380 kg/m 2 . Plaster
or dry-lined finish both sides. Brick work joints
well filled. 1 )
d) 'No fines' concrete 225 mm thickness, weight
(including plaster) not less than 415 kg/m 2 . Plaster
or dry-lined finish both sides. X)
Table 15 — Concluded
(l)
(2)
e) Cavity lightweight aggregate block (maximum
density of block 1 600 kg/m 3 ) with 75 mm cavity
and wall ties of the butterfly wire type. Dry
lined finish on both sides. Joints in blockwork
well filled. Overall mass per unit area not less than
300 kg/m 2 . »
f) Dense aggregate concrete block cavity wall with
50 mm cavity and wall ties of the butterfly wire
type. Dry lined finish on both sides. Joints in block
, work well filled. Overall mass per unit area not
less than 415 kg/m 2 . 1 *
g) Autoclaved aerated concrete block cavity wall
consisting of two leaves, 100 mm blocks not less
than 75 mm apart, with wall ties of the butterfly
type. Plaster or dry line finish on both sides. Joints
in blockwork well filled. Overall mass per unit
area not less than 150 kg/m 2 . 1 *
54 to 60 a) Two separate frames of timber studs not less than
100 mm x 50 mm spaced at 600 mm maximum
centres. A 50 mm mineral wool quilt in each frame
between studs. Frames spaced to give a minimum
300 mm overall cavity. Each frame clad on outside
with three layers of 12.5 mm plasterboard
nailed to framing. Approximate mass per unit area
51 kg/m 2 . 1 *
b) Two separate frames of boxed *C section
galvanized nominal 150 mm steel studs 100 mm
apart with a 400 mm overall cavity. 50 mm
mineral wool quilt fixed to the back of one frame
each frame clad on outside with three layers
of 12.5 mm plasterboard by self drilling or
tapping screws. Approximate mass per unit area
47 kg/m 2 . 1 *
c) Solid masonry with an overall mass per unit
area of not less than 700 kg/m 2 fully sealed both
sides. ])
d) Dense aggregate concrete block solid wall
215 mm thick plaster finish to both surfaces.
Overall mass per unit area not less than 415 kg/m 2 . 1 )
e) Cavity lightweight aggregate block (maximum
density of block 1 600 kg/m 3 ) with 75 mm cavity
and wall ties of the butterfly wire type. Plaster
finish on both sides. Joints in blockwork well
filled. Overall mass per unit area not less than
300 kg/m 2 . 1 *
f) Dense aggregate concrete block cavity wall with
50 mm cavity and wall ties of the butterfly wire
type. Plaster finish on both sides, Joints in
blockwork well filled. Overall mass per unit area
not less than 4*5 kg/m 2 . 1 )
NOTES
1 Construction details and workmanship are
important if the levels of sound insulation
indicated are to be achieved.
2 Where plasterboard is specified it is assumed
that the surface mass will be at least 6.5 kg/m 2 for
9.5 mm thick board, at least 8.5 kg/m 2 for 12.5 mm
thick board, and at least 14,5 kg/m 2 for 19 mm
thick board. If less dense plasterboard is used, the
thickness should be increased.
]) When considering these constructions for separating walls,
expert advice should be sought.
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
39
Table 16 Air-borne and Impact Sound
Insulation of Floor Constructions
(Clause F-4)
Table 16 — Concluded
(1)
(2)
Sound
Insulation
dB
(1)
Type of Wall or Partition
(2)
A concrete floor having mass per unit area
: 56 to 65 not less than 365 kg/m 2 , including any screed
or ceiling finish directly bonded to the floor
slab; together with a floating floor or resilient
floor covering equivalent to rubber or sponge
rubber underlay or thick cork tile (for
example carpet and underlay or sponge
rubber backed vinyl flooring).
b) A solid floor consisting of:
1) a solid slab; or
2) concrete beams and infilling blocks; or
3) hollow concrete planks; together with a
floating floor. A ceiling finish is required
for a beam and block floor. In each case
the slab should have a mass per unit area
of at least 300 kg/m 2 including any screed
or ceiling finish directly bonded to it.
Where a floating floor is laid over a floor of
beams and hollow infill blocks or hollow
beams along the top of the structural floor, it
should be sealed and levelled before the
resilient layer is put down. It is also essential
to have due regard for conduits and pipework
which should be laid and covered so as to
prevent any short circuit of the floor's
isolating properties.
If precast units are used as a structural floor,
it is essential that the joints are filled to ensure
that the sound insulation performance is
maintained.
The resilient material is laid to cover
completely the structural floor and turned up
against the surrounding wall along all edges.
The resilient layer is usually of mineral fibre,
or a special grade of expanded polystyrene.
When the screed is laid, it is important that
none of the mix finds its way through the
resilient layer to the structural floor, as this
will short circuit the isolation between the two
decks and significantly reduce the sound
insulation.
c) A floor consisting of boarding nailed to
battens laid to float upon an isolating layer
of mineral fibre capable of retaining its
resilience under imposed loading. With
battens running along the joists, a dense fibre
layer can be used in strips. The ceiling below
to be of metal lath and plaster not less than
29 mm thick, with pugging on the ceiling
such that the combined mass per unit area of
the floor, ceiling and pugging is not less than
120 kg/m 2 . This construction will only give
values for D nT , w of 50 to 53 dB, and a value
forZ/ nT , w of75dB.
d) A floor consisting of 18 mm tongued and
grooved chipboard on 19 mm plasterboard
laid on battens running parallel to the
joists and supported on 25 mm thick
mineral wool of about 90 kg/m 3 to 140 kg/
m 3 density; 100 mm of fibre absorbent
(as used for insulation in roof spaces)
laid between the joists on top of the
plasterboard ceiling. 13
e) A floor consisting of 18 mm tongued and
grooved chipboard on 19 mm plasterboard
floating on a 25 mm thick mineral wool layer
of about 60 kg/m 3 to 80 kg/m 3 density; this
on a 12.5 mm plywood platform; 100 mm
of fibre absorbent laid between the joists on
top of the plasterboard ceiling.
T , w - 32 to 36 Timber joist floor consisting of 22 mm
= 80 to 85 tongued and grooved floor boarding or
equivalent fixed directly to floor joists.
Ceiling of 12.5 mm plasterboard and skim
with no floor covering.
NOTES
1 Construction details and workmanship are important if the
levels of sound insulation indicated are to be achieved.
2 Where plasterboard is specified it is assumed that the surface
mass will be at least 8.5 kg/m 3 for 12.5 mm thick board, and at
least 14.5 kg/m 2 for 19 mm thick board. If less dense
plasterboard is used, the thickness should be increased.
l) In these types of floor construction, the ceiling may be 19 mm
plus 12.5 mm plasterboard. It is imperative that the resilient
layer is not punctured by nails.
In many cases, simple solid partitions give insulation
values according to their mass (see F-3.3). Moreover,
with partitions of this type there is usually little
variation between field and laboratory test results
unless fhe laboratory insulation exceeds 45 dB.
Exceptions may occur in buildings that have not been
specially designed to minimize common cavities and
strongly coupled element* in lightweight panelling.
The examples given are not exhaustive. Flanking
structures are not listed since these can vary widely
and are often dependent upon other factors such as
thermal insulation, which are outside the scope of this
Code.
40
NATIONAL BUILDING CODE OF INDIA
ANNEX G
(Clause 13.1)
BASIC DESIGN TECHNIQUES FOR NOISE CONTROL IN AIR CONDITIONING,
HEATING AND MECHANICAL VENTILATION SYSTEM
G- 1 When selecting fans and other related mechanical
equipment and when designing air distribution systems
to minimize the sound transmitted from different
components to the occupied spaces that they serve, the
following recommendations should be considered:
a) Design the air distribution system to minimize
flow resistance and turbulence. High flow
resistance increases the required fan pressure,
which results in higher noise being generated
by the fan. Turbulence increases the flow
noise generated by duct fittings and dampers
in the air distribution system, especially at low
frequencies.
b) Select a fan to operate as near as possible to
its rated peak efficiency when handling the
required quantity of air and static pressure.
Also, select a fan that generates the lowest
possible noise but still meets the required
design conditions for which it is selected.
Using an oversized or undersized fan that
does not operate at or near rated peak
efficiency may result in substantially higher
noise levels.
c) Design duct connections at both the fan inlet
and outlet for uniform and straight air flow.
Failure to do this may result in severe
turbulence at the fan inlet and outlet and in
flow separation at the fan blades. Both of
these may significantly increase the noise
generated by the fan.
d) Select duct silencers that do not significantly
increase the required fan total static pressure.
e) Place fan-powered mixing boxes associated
with variable volume air distribution systems
away from noise-sensitive areas.
f) Minimize flow-generated noise by elbows or
duct branch take-offs, whenever possible, by
locating them at least four to five duct
diameters from each other. For high velocity
systems, it may be necessary to increase this
distance to up to ten duct diameters in critical
noise areas.
g) Keep airflow velocity in the duct as low as
possible (7.5 m/s or less) near critical noise
areas by expanding the duct cross-section
area. However, do not exceed an included
expansion angle of greater than 15°. Flow
separation, resulting from expansion angles
greater than 15°, may produce rumble noise.
Expanding the duct cross-section area will
reduce potential flow noise associated with
turbulence in these areas.
h) Use turning vanes in large 90° rectangular
elbows and branch takeoffs. This provides a
smoother transmission in which the air
can change flow direction, thus reducing
turbulence.
j) Place grilles, diffusers and registers into
occupied spaces as far as possible from
elbows and branch takeoffs.
k) Minimize the use of volume dampers near
grills, diffusers and registers in acoustically
critical situations.
m) Vibration isolate all vibrating reciprocating
and rotating equipment if mechanical
equipment is located on upper floors or is
roof-mounted. Also, it is usually necessary
to vibration isolate the mechanical equipment
that is located in the basement of a building
as well as piping supported from the ceiling
slab of a basement, directly below tenant
space. It may be necessary to use flexible
piping connectors and flexible electrical
conduit between rotating or reciprocating
equipment and pipes and ducts that are
connected to the equipment.
n) Vibration isolate ducts and pipes, using
spring and/or neoprene hangers for at least
the first 15 m from the vibration-isolated
equipment.
p) Use barriers near outdoor equipment when
noise associated with the equipment will
disturb adjacent properties if barriers are not
used. In normal practice, barriers typically
produce no more than 15 dB of sound
attenuation in the mid-frequency range.
q) Table 17 lists several common sound sources
associated with mechanical equipment noise.
Anticipated sound transmission paths and
recommended noise reduction methods are
also listed in Table 18. Air-borne and/or
structure-borne sound can follow any or all
of the transmission paths associated with a
specified sound source.
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
41
Table 17 Sound Sources, Transmission Paths and Recommended
Noise Reduction Methods
[Clause G-l(q)]
Sound Source Path No.
(see Table 18)
Circulating fans, grilles, registers, diffusers, unitary equipment in room 1
Induction coil and fan-powered VAV mixing units 1,2
Unitary equipment located outside of room served; remotely located air-handling equipment, such as fans, blowers, 2, 3
dampers, duct fitting, and air washers
Compressors, pumps, and other reciprocating and rotating equipment (excluding air-handling equipment) 4, 5, 6
Cooling towers; air-cooled condensers 4, 5, 6, 7
Exhaust fans; window air conditioners 7, 8
Sound transmission between rooms 9, 10
Table 18 Sound Transmission Paths and Recommended
Noise Reduction Methods
[Clause G-l(q) and Table 17]
Path
Transmission Paths
Noise Reduction Methods
No.
(1)
(2)
(3)
1 Direct sound radiated from sound sources to ear.
Reflected sound from walls, ceiling and floor.
2 Air and structure-borne sound radiated from casings and
through walls of ducts and plenums is transmitted through
walls and ceiling into rooms.
3 Airborne sound radiated through supply and return air
ducts to diffusers in room and then to listener by Path 1 .
4 Noise transmitted through equipment room walls and
floors to adjacent rooms.
5 Vibration transmitted via building structure to adjacent
walls and ceilings, from which it radiates as noise into
room by Path 1 .
6 Vibration transmission along pipes and duct walls.
7 Noise radiated to outside enters room windows.
8 Inside noise follows Path 1 .
9 Noise transmitted to an air diffusers in a room, into a duct,
and out through an air diffuser in another room.
10 Sound transmission through, over, and around room
partition.
Direct sound can be controlled only by selecting quiet equipment.
Reflected sound is controlled by adding sound absorption to the
room and to equipment location.
Design duct and fittings for low turbulence; locate high velocity
ducts in non-critical areas; isolate ducts and sound plenums from
structure with neoprene or spring hangers
Select fans for minimum sound power; use ducts lined with sound-
absorbing material; use duct silencers or sound plenums in supply
and return air ducts.
Locate equipment rooms away from critical areas; use masonry
blocks or concrete for equipment room walls and floor.
Mount all machines on properly designed vibration isolators; design
mechanical equipment room for dynamic loads; balance rotating
and reciprocating equipment.
Isolate pipe and ducts from structure with neoprene or spring
hangers; install flexible connectors between pipes, ducts, and
vibrating machines.
Locate equipment away from critical areas; use barriers and covers
to interrupt noise paths; select quiet equipment.
Select quiet equipment.
Design and install duct attenuation to match transmission loss of
wall between rooms.
Extend partition to ceiling slab and tightly seal all around; seal all
pipe, conduit, duct and other partition penetrations.
ANNEX H
(Clause 13.2)
SUGGESTED EQUIPMENT NOISE DATA SHEET
It is recommended that an equipment noise data sheet
be furnished to intending bidders of mechanical
equipment such as air conditioning, heating and
mechanical ventilation machinery or diesel generating
units specifying noise requirements at the time of
request for quotation. Following is a sample noise data
sheet suggested for the purpose:
42
NATIONAL BUILDING CODE OF INDIA
Sample of Equipment Noise Data Sheet for Noise Specification
to be Sent to Suppliers
Equipment Description .
Type.
. Item No.
Octave -Band
Centre Frequency,
Hz
(1)
Desired Sound
Pressure Level,
L P
(2)
Supplier to Complete
Actual
(3)
Special Design
(4)
Special Noise Control
Measures Recommended
(5)
63
125
250
500
1000
2 000
4 000
8 000
NOTES
1 The measurements of SPL shall be at a distance of 1.0 m from the equipment and 1 .5 m above grade or floor. The measurement
method shall be described and the point of maximum levels furnished.
2 Complete col 3 for actual levels of standard equipment.
3 Complete col 4 for special design for low noise (if such alternative is available).
4 Complete col 5 for noise control measures such as enclosure.
5 Indicate if the equipment meets the specified noise levels without modification (Yes/No).
6 If no, additional costs required:
For col 4
For col 5
It will be observed from the col 3, 4 and 5 that the
buyer would get quotation for supply of a standard
equipment at a price P-l, whose noise characteristics
would be as per col 3. Col 4 would indicate acoustical
performance for a special design at a price P-2. Col 5
would indicate the acoustical performance if the
owners were to provide special noise control measures
for the installation (whose broad details and
approximate estimated cost is also furnished by the
vendor).
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and 'accepted standards'
in the fulfilment of the requirements of the Code. The
latest version of a standard shall be adopted at the time
of enforcement of the Code. The standards listed may
be used by the Authority as a guide in conformance
with the requirements of the referred clauses in the
Code.
IS No. Title
(1) 11050 Rating of sound insulation in
(Part 1) : 1984 buildings and of building
elements: Part 1 Air-borne
sound insulation in buildings
and of interior building elements
Title
Recommendations for noise
abatement in town planning
Code of practice for acoustical
design of auditoriums and
conference halls
Rating of sound insulation in
buildings and of building
elements:
(Part 1) : 1984 Air-borne sound insulation in
buildings and of interior
building elements
(Part 2) : 1984 Impact sound insulation
IS No.
(2) 4954: 1968
(3) 2526 : 1963
(4) 11050
PART 8 BUILDING SERVICES — SECTION 4 ACOUSTICS, SOUND INSULATION AND NOISE CONTROL
43
NATIONAL BUILDING CODE OF INDIA
PART 8 BUILDING SERVICES
Section 5 Installation of Lifts and Escalators
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 GENERAL
4 ESSENTIAL REQUIREMENTS
5 DIMENSIONAL TOLERANCES
6 PRELIMINARY DESIGN
7 POWER AND CONTROL SYSTEMS
8 CONDITIONS FOR OPTIMUM PRACTICE
9 RUNNING AND MAINTENANCE
1 LIFT ENQUIRY OR INVITATION TO TENDER
1 1 ACCEPTANCE OF TENDER AND SUBSEQUENT PROCEDURE
1 2 CO-ORDINATION OF SITE WORK
1 3 PROCEDURE FOLLOWING TEST, INCLUDING INSPECTION AND
MAINTENANCE
14 ESCALATORS
LIST OF STANDARDS
5
5
9
11
21
22
28
33
35
35
37
38
39
40
42
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
This Section was first published in 1970 and was subsequently revised in 1983. This Section covers the essential
requirements for installation of lifts and escalators in buildings. This Section shall, however, be read with
Part 4 Tire and Life Safety' from fire safety requirements point of view. The major changes in the last revision
were addition of outline dimensions of different types of lifts and detailed requirements of escalators in buildings.
Emphasis was laid on coordination between the engineer/architect and the lift manufacturer to arrive at the
number and position of lifts for attaining optimum efficiency in serving the building with safety.
As a result of experience gained in implementation of 1983 version of the Code and feedback data received as
well as revision of Indian Standards on which this Section was based, a need was felt to revise this Section. This
revision has, therefore, been prepared to take care of these. The significant changes incorporated in this revision
includes:
a) New clauses/recommendations have been added on Building Management System.
b) New clauses have been added on fireman's lift, infra-red light curtain safety and Braille button for blind
people.
c) The provisions have been updated as per the revised standards on lifts on which this Section is based.
d) The list of Indian Standards as good practices/accepted standards has been updated.
The information contained in this Section is largely based on the following Indian Standards:
IS No. Title
962 : 1989 Code of practice for architectural and building drawings (second revision)
4591 : 1968 Code of practice for installation and maintenance of escalators
14665 Specification for electric traction lifts:
(Part 1 ) : 2000 Guidelines for outline dimensions of passenger, goods, service and hospital
lifts
(Part 2/Sec 1 & 2) : 2000 Code of practice for installation, operation and maintenance, Section 1
Passenger and goods lifts, Section 2 Service lifts
(Part 3/Sec 1 & 2) : 2000 Safety rules, Section 1 Passenger and goods lifts, Section 2 Service lifts
(Part 4/Sec 1 to 9) : 2001 Components, Section 1 Lift buffers, Section 2 Lift guide rails and guide shoes,
Section 3 Lift carframe, car, counterweight and suspension, Section 4 Lift
safety gears and governors, Section 5 Lift retiring cam, Section 6 Lift doors
and locking devices and contacts, Section 7 Lift machines and brakes,
Section 8 Lift wire ropes, Section 9 Controller and operating devices
(Part 5) : 1999 Inspection manual
All standards, whether given herein above or cross-referred to in the main text of this Section, are subject to
revision. The parties to agreement based on this Section are encouraged to investigate the possibility of applying
the most recent editions of the standards.
PART 8 BUILDING SERVICES — SECTION 5 INSTALLATION OF LIFTS AND ESCALATORS
NATIONAL BUILDING CODE OF INDIA
PART 8 BUILDING SERVICES
Section 5 Installation of Lifts and Escalators
1 SCOPE
1.1 This Section covers the essential requirements for
the installation, operation and maintenance and also
inspection of lifts (passenger lifts, goods lifts, hospital
lifts, service lifts and dumb waiter) and escalators so
as to ensure safe and satisfactory performance.
1.2 This Section gives information that should be
exchanged among the architect, the consulting engineer
and the lift/escalator manufacturer from the stage of
planning to installation including maintenance.
NOTE — The provisions given in this Section are primarily
for electric traction lift; however, most of these provisions are
also applicable to hydraulic lifts {see good practice [8-5(1)}.
2 TERMINOLOGY
2.0 For the purpose of this Section, the following
definitions shall apply.
2.1 Automatic Rescue Device — A device meant to
bring a lift stuck between floors due to loss of power,
to the nearest level and open the doors in order to allow
trapped passengers to be evacuated. Such a device may
use some form of internal auxiliary power source
for such purpose, complying with all the safety
requirements of a lift during normal run. The speed of
travel is usually lower than the normal speed. In the
case of manual doors on reaching the level, the device
shall allow the door to be opened and in case of power
operated doors the device shall automatically open the
door.
2.2 Baluster -
bulging below.
A short pillar slender above and
2.2.1 Balustrade — A row of balusters meant for
supporting moving handrails.
2.3 Bottom Car Runby — The distance between the
car buffer striker plate and the striking surface of the
car buffer when the car is in level with the bottom
terminal landing.
2.4 Bottom Coutnerweight Runby — The distance
between the counter weight buffer striker plate and
the striking surface of the counterweight buffer when
the car is in level with the top terminal landing.
2.5 Buffer — A device designed to stop a descending
car or counter weight beyond its normal limit of travel
by storing or by absorbing and dissipating the kinetic
energy of the car or counterweight.
2.5.1 Oil Buffer — A buffer using oil as a medium
which absorbs and dissipates the kinetic energy of the
descending car or counterweight.
2.5.1.1 Oil buffer stroke — The oil displacing
movement of the buffer plunger or piston, excluding
the travel of the buffer plunger accelerating device.
2.5.2 Spring Buffer -~ A buffer which stores in a spring
the kinetic energy of the descending car or
counterweight,
2.5.2.1 Spring buffer load rating — The load required
to compress the spring by an amount equal to its stroke.
2.5.2.2 Spring buffer stroke — The distance, the
contact end of the spring can move under a compressive
load until the spring is compressed solid.
2.6 Call Indicator — A visual and audible device in
the car to indicate to the attendant the lift landings from
which calls have been made.
2.7 Car Bodywork — The enclosing bodywork of
the lift car which comprises the sides and roof and is
built upon the car platform.
2.8 Car Door Electric Contact — An electric device,
the function of which is to prevent operation of the
driving machine by the normal operating device unless
the car door is in the closed position.
2.9 Car Frame — The supporting frame or sling to
which the platform of the lift car, its safety gear, guide
shoes and suspension ropes are attached.
2.10 Car Platform — The part of the lift car which
forms the floor and directly supports the load.
2.11 Clearance
2.11.1 Bottom Car Clearance — The clear vertical
distance from the pit floor to the lowest structural or
mechanical part, equipment or device installed beneath
the car platform aprons or guards located within
300 mm, measured horizontally from the sides of the
car platform when the car rests on its fully compressed
buffers.
2.11.2 Top Car Clearance — The shortest vertical
distance between the top of the car crosshead, or
between the top of the car where no crosshead is
provided, and the nearest part of the overhead structure
or any other obstruction when the car floor is level
with the top terminal landing.
2.11.3 Top Counterweight Clearance — The shortest
vertical distance between any part of the counterweight
PART 8 BUILDING SERVICES — SECTION 5 INSTALLATION OF LIFTS AND ESCALATORS
structure and the nearest part of the overhead structure
or any other obstruction when the car floor is level
with the bottom terminal landing.
2.12 Control — The system governing starting,
stopping, direction of motion, acceleration, speed and
retardation of moving member.
2.12.1 Single-Speed Alternating Current Control —
A control for a driving machine induction motor which
is arranged to run at a single-speed.
2.12.2 Two-Speed Alternating Current Control — A
control for a two-speed driving machine induction
motor which is arranged to run at two different
synchronous speeds either by pole changing of a single
motor or by two different armatures.
2.12.3 Rheostatic Control — A system of control
which is accomplished by varying resistance or
reactance or both in the armature or field circuit or
both of the driving machine motor.
2.12.4 Variable Voltage Motor Control (Generator
Field Control) — A system of control which is
accomplished by the use of an individual generator
for each lift wherein the voltage applied to the driving
machine motor is adjusted by varying the strength and
direction of the generator field.
2.12.5 Electronic Devices — A system of control
which is accomplished by the use of electronic devices
for driving the lift motor at variable speed.
2.12.6 Alternating Current Variable Voltage (ACW)
Control — A system of speed control which is
accomplished by varying the driving and braking
torque by way of voltage variation of the power supply
to the driving machine induction motor.
2.12.7 Alternating Current Variable Voltage Variable
Frequency (ACVWF) Control — A system of speed
control which is accomplished by varying the voltage
and frequency of the power supply to the driving
machine induction motor.
2.12.8 Solid-State d.c. Variable Voltage Control —
A solid-state system of speed control which is
accomplished by varying the voltage and direction of
the power supply to the armature of driving machine
d.c. motor.
2.13 Counterweight — A weight or series of weights
to counter-balance the weight of the lift car and part of
the rated load.
2.14 Deflector Sheave — An idler pulley used to
change the direction of a rope lead.
2.15 Door
2.15.1 Door, Centre Opening Sliding — A door which
slides horizontally and consists of two or more panels
which open from the centre and are usually so
interconnected that they move simultaneously.
2.15.2 Door, Mid-Bar Collapsible — A collapsible
door with vertical bars mounted between the normal
vertical members.
2.15.3 Door, Multipanel — A door arrangement
whereby more than one panel is used such that the
panels are connected together and can slide over one
another by which means the clear opening can be
maximized for a given shaft width. Multipanels are
used in centre opening and two speed sliding doors.
2.15.4 Door, Single Slide — A single panel door
which slides horizontally.
2.15.5 Door, Two Speed Sliding — A door which
slides horizontally and consists of two or more panels,
one of which moves at twice the speed of the other.
2.15.6 Door, Vertical Bi-parting — A door which
slides vertically and consists of two panels or sets of
panels that move away from each other to open and
are so interconnected that they move simultaneously.
2.15.7 Door, Vertical Lifting — A single panel door,
which slides in the same plane vertically up to open.
2.15.8 Door, Swing — A swinging type single panel
door which is opened manually and closed by means
of a door closer when released.
2.16 Door Closer — A device which automatically
closes a manually opened door.
2.17 Door Operator — A power-operated device for
opening and closing doors.
2.18 Dumb Waiters — A lift with a car which moves
in guides in a vertical direction; has a net floor area of
1 m 2 , total inside height of 1.2 m, whether or not
provided with fixed or removable shelves; has a
capacity not exceeding 250 kg and is exclusively used
for carrying materials and shall not carry any person.
2.19 Electrical and Mechanical Interlock — A
device provided to prevent simultaneous operation of
both up and down relays.
2.20 Electro-Mechanical Lock — A device which
combines in one unit, electrical contact and a
mechanical lock jointly used for the landing and/or
car doors.
2.21 Emergency Stop Push or Switch — A push
button or switch provided inside the car designed to
open the control circuit to cause the lift car to stop
during emergency.
2.22 Escalator — A power driven, inclined, continuous
stairway used for raising or lowering passengers.
NATIONAL BUILDING CODE OF INDIA
2.23 Escalator Installation — It includes the
escalator, the track, the trusses or girders, the
balustrading, the step treads and landings and all chains,
wires and machinery directly connected with the
operation of the escalator.
2.24 Escalator Landing — The portion of the
building or structure which is used to receive or
discharge passengers into or from an escalator.
2.25 Escalator Landing Zone — A space extending
from a horizontal plane 40 cm below a landing to a
plane 40 cm above the landing.
2.26 Escalator Machine — The mechanism and other
equipment in connection therewith used for moving
the escalator
2.27 Floor Levelling Switch — A switch for bringing
the car to level at slow speed in case of double speed
or variable speed machines.
2.28 Floor Selector — A mechanism forming a part
of the control equipment, in certain automatic lifts,
designed to operate controls which cause the lift car to
stop at the required landings.
2.29 Floor Stopping Switch — A switch or
combination of switches arranged to bring the car to
rest automatically at or near any pre-selected landing.
2*30 Gearless Machine — A lift machine in which
the motive power is transmitted to the driving sheave
from the motor without intermediate reduction gearing
and has the brake drum mounted directly on the motor
shaft.
2.31 Goods Lift — A lift designed primarily for the
transport of goods, but which may carry a lift attendant
or other persons necessary for the loading or unloading
of goods.
2.32 Guide Rails — The members used to guide the
movement of a lift car or counterweight in a vertical
direction.
2.33 Guide Rails Fixing — The complete assy,
comprising the guide rails bracket and its fastenings.
2.34 Guide Rails Shoe — An attachment to the car
frame or counterweight for the purpose of guiding the
lift car or counter weight frame.
2.35 Hoisting Beam — A beam, mounted immediately
below the machine room ceiling, to which lifting tackle
can be fixed for raising or lowering parts of the lift
machine.
2.36 Hospital Lift — A lift normally installed in
a hospital/dispensary/clinic and designed to
accommodate one number bed/stretcher along its
depth, with sufficient space around to carry a minimum
of three attendants in addition to the lift operator.
2.37 Landing Call Push — A push button fitted at a
lift landing, either for calling the lift car, or for actuating
the call indicator.
2.38 Landing Door — The hinged or sliding portion
of a lift well enclosure, controlling access to a lift car
at a lift landing.
2.39 Landing Zone — A space extending from a
horizontal plane 400 mm below a landing to a plane
400 mm above the landing.
2.40 Levelling Devices
2.40.1 Levelling Device, Lift Car — Any mechanism
which either automatically or under the control of the
operator, moves the car within the levelling zone
towards the landing only, and automatically stops it at
the landing.
2.40.2 Levelling Device, One Way Automatic — A
device which corrects the car level only in case of under
run of the car but will not maintain the level during
loading and unloading.
2.40.3 Levelling Device, Two-Way Automatic
Maintaining — A device which corrects the car level
on both under run and over-run and maintains the level
during loading and unloading.
2.40.4 Levelling Device, Two Way Automatic Non-
Maintaining — A device which corrects the car level
on both under run and over run but will not maintain
the level during loading and unloading.
2.41 Levelling Zone — The limited distance above
or below a lift landing within which the levelling
device may cause movement of the car towards the
landing.
2.42 Lift — An appliance designed to transport
persons or materials between two or more levels in a
vertical or substantially vertical direction by means of
a guided car or platform. The word 'elevator' is also
synonymously used for 'lift'.
2.43 Lift Car — The load carrying unit with its floor
or platform, car frame and enclosing bodywork.
2.44 Lift Landing — That portion of a building or
structure used for discharge of passengers or goods or
both into or from a lift car.
2.45 Lift Machine — The part of the lift equipment
comprising the motor and the control gear therewith,
reduction gear (if any), brake(s) and winding drum or
sheave, by which the lift car is raised or lowered.
2.46 Lift Pit — The space in the lift well below the
level of the lowest lift landing served.
2.47 Lift Well — The unobstructed space within an
enclosure provided for the vertical movement of the
PART 8 BUILDING SERVICES — SECTION 5 INSTALLATION OF LIFTS AND ESCALATORS
lift car(s) and any counterweight(s), including the lift
pit and the space for top clearance.
2.48 Lift Well Enclosure — Any structure which
separates the lift well from its surroundings.
2.49 Operation — The method of actuating the control
of lift machine.
2.49.1 Automatic Operation — A method of operation
in which by a momentary pressure of a button the lift
car is set in motion and caused to stop automatically at
any required lift landing.
2.49.2 Non-Selective Collective Automatic Operation
~~ Automatic operation by means of one button in the
car for each landing level served and one button at
each landing, wherein all stops registered by the
momentary actuation of landing or car buttons are made
irrespective of the number of buttons actuated or of
the sequence in which the buttons are actuated. With
this type of operation, the car stops at all landings for
which buttons have been actuated making the stops in
the order in which the landings are reached after the
buttons have been actuated but irrespective of its
direction of travel.
2.49.3 Selective Collective Automatic Operation —
Automatic operation by means of one button in the
car for each landing level served and by up and down
buttons at the landings, wherein all stops registered by
the momentary actuation of the car made as defined
under non-selective collective automatic operation, but
wherein the stops registered by the momentary
actuation of the landing buttons are made in the order
in which the landings are reached in each direction of
travel after the buttons have been actuated. With this
type of operation, all 'up' landing calls are answered
when the car is travelling in the up direction and all
'down' landing calls are answered when the car is
travelling in the down direction, except in the case of
the uppermost or lowermost calls which are answered
as soon as they are reached irrespective of the direction
of travel of the car.
2.49.4 Single Automatic Operation — Automatic
operation by means of one button in the car for each
landing level served and one button at each landing so
arranged that if any car or landing button has been
actuated, the actuation of any other car or landing
operation button will have no effect on the movement
of the car until the response to the first button has been
completed.
2.49.5 Group Automatic Operation — Automatic
operation of two or more non-attendant lifts equipped
with power-operated car and landing doors. The
operation of the cars is co-ordinated by a supervisory
operation system including automatic dispatching
means whereby selected cars at designated dispatching
points automatically close their doors and proceed on
their trips in a regulated manner.
Typically, it includes one button in each car for each
floor served and up and down buttons at each landing
(single buttons at terminal landings). The stops set up
by the momentary actuation of the car buttons are made
automatically in succession as a car reaches the
corresponding landings irrespective of its direction of
travel or the sequence in which the buttons are actuated.
The stops set up by the momentary actuation of the
landing buttons may be accomplished by any lift in
the group, and are made automatically by the first
available car that approaches the landing in the
corresponding direction.
2.49.6 Car Switch Operation — Method of operation
by which the movement of lift car is directly under the
operation of the attendant by means of a handle.
2.49.7 Signal Operation — Same as collective
operation, except that the closing of the door is initiated
by the attendant.
2.49.8 Double Button (Continuous Pressure)
Operation — Operation by means of buttons or
switches in the car and at the landings any of which
may be used to control the movement of the car as
long as the button or switch is manually pressed in the
actuating position.
2.50 Operating Device — A car switch, push button
or other device employed to actuate the control.
2.51 Overhead Beams — The members, usually of
steel, which immediately support the lift equipment at
the top of the lift well.
2.52 Over Speed Governor — An automatic device
which brings the lift car and/or counter weight to rest
by operating the safety gear in the event of the speed in
a descending direction exceeding a predetermined limit.
2.53 Passenger Lift — A lift designed for the transport
of passengers.
2.54 Position and/or Direction Indicator — A device
which indicates on the lift landing or in the lift car or
both, the position of tfye car in the lift well or the
direction or both in which the lift car is travelling.
2.55 Rated Load (Lift) — The maximum load for
which the lift car is designed and installed to carry
safely at its rated speed.
2.56 Rated Load (Escalator) — The load which the
escalator is designed and installed to lift at the rated
speed.
2.57 Rated Speed (Lift) — The mean of the maximum
speed attained by the lift car in the upward and
downward direction with rated load in the lift car.
8
NATIONAL BUILDING CODE OF INDIA
2.58 Rated Speed (Escalator) — The speed at which
the escalator is designed to operate. It is the rate of
travel of the steps, measured along the angle of
inclination, with rated load on the steps or carriage.
2.59 Retiring Cam — A device which prevents the
landing doors from being unlocked by the lift car unless
it stops at a landing.
2.60 Roping Multiple — A system of roping where,
in order to obtain a multiplying the factor from the
machine to the car, multiple falls of rope are run around
sheave on the car or counterweight or both. It includes
roping arrangement of 2 to4.3 to 1 etc.
2.61 Safety Gear — A mechanical device attached to
the lift car or counterweight or both, designed to stop
and to hold the car or counterweight to the guides in
the event of free fall, or, if governor operated, of over-
speed in the descending direction. Any anticipated
impact force shall be added in the general drawing or
layout drawing.
2.62 Service Lift — A passenger cum goods lift meant
to carry goods along with people.
Typically in an office building this may be required to
carry food or stationeries, in a residential building to
carry a bureau or accommodate a stretcher and in a
hotel to be used for food trolleys or baggage. There is
a need in such lifts, to take care of the dimensions of
the car and the door clear opening in line with the type
of goods that may have to be carried based on mutual
discussion between supplier and customer. Also, such
lifts shall have buffer railings in the car at suitable
height to prevent damage to the car panels when the
goods are transported. Typically such lifts, if provided
with an automatic door, may use some means to detect
trolleys and stretcher movement in advance to protect
the doors against damage. The car floor load
calculations and car area of such a lift is as in the case
of a passenger lift except that these are not meant to
carry heavy concentrated loads.
2.63 Sheave — A rope wheel, the rim of which is
grooved to receive the suspension ropes but to which
the ropes are not rigidly attached and by means of
which power is transmitted from the lift machine to
the suspension ropes.
2.64 Slack Rope Switch — Switch provided to open
the control circuit in case of slackening of rope(s)
2.65 Suspension Ropes — The ropes by which the
car and counter weight are suspended.
2.66 Terminal Slow Down Switch — A switch when
actuated shall compulsorily cut off the high speed and
switch on the circuitry to run the lift in levelling speed
before reaching on terminal landings.
2.67 Terminal Stopping Switch Normal — Switch
for cutting all the energizing current in case of car
travelling beyond the top bottom landing or a switch
cuts off the energizing current so as to bring the car to
stop at the top and bottom level.
2.68 Terminal Stopping Device Final — A device
which automatically cause the power to be removed
from an electric lift driving machine motor and brake,
independent of the functioning of the normal terminal
stopping device, the operating device or any emergency
terminal stopping device, after the car has passed a
terminal landing.
2.69 Total Headroom — The vertical distance from
the level of the top lift landing to the bottom of the
machine room slab.
2.70 Travel — The vertical distance between the
bottom and top lift handing served.
2.71 Geared Machine — A machine in which the
power is transmitted to the sheave through worm or
worm and spur reduction gearing.
3 GENERAL
3.1 The appropriate aspect of lift and escalator
installation shall be discussed during the preliminary
planning of the building with all the concerned parties,
namely, client, architect, consulting engineer and/or
lift/escalator manufacturer. This enables the lift/escalator
manufacturer to furnish the architect and/or consulting
engineer with the proposed layout on vice-versa.
3.2 Exchange of Information
3.2.1 If the proposed installation is within the scope
of 6, the guidelines laid down together with Fig. 1 will
enable the preliminary scheme for the installation to
be established.
Figure 1 shows only some of the typical arrangements
and variations are possible with respect to number of
lifts and the layout.
Although the recommended outline for the various
classes of lifts given in 6 enables the general planning
details to be determined by the architect, these should
be finally settled at the earliest possible stage by detailed
investigation with the purchaser's representative
reaching agreement with the lift maker where necessary
before an order is finally placed. This will enable a
check to be made and information to be exchanged on
such vital matters as:
a) the number, capacity, speed and disposition
of the lifts necessary to give adequate lift
service in the proposed building.
b) the provision of adequate access to the
machine room.
PART 8 BUILDING SERVICES — SECTION 5 INSTALLATION OF LIFTS AND ESCALATORS
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1C ARRANGEMENT FOR SIX LIFTS 1D ARRANGEMENT FOR EIGHT LIFTS
Fig. 1 Arrangement of Lifts
c) The loads which the lift will impose on the
building structure, and the holes to be left in
the machine room floor and cut-outs for wall
boxes for push-buttons and signals;
d) The necessity for and type of insulation to
minimize the transmission of vibration and
noise to other parts of the building;
e) The special requirements of local authorities
and other requirements set out in the 'planning
permit';
f) The need for the builder to maintain accuracy
of building as to dimensions and in plumb;
g) The periods of time required for preparation
and approval of relevant drawings for
manufacturing and the installation of the lift
equipment;
h) The requirements for fixing guide brackets
to the building structure;
j) The time at which electric power will be
required before completion to allow for
testing;
k) The requirements for electrical supply
feeders, etc;
m) The requirements for scaffolding in the lift
well and protection of the lift well prior to
and during installation of equipment; and
n) Delivery and storage of equipment.
3.2.2 Information to be Provided by Architect or
Engineer
As a result of preliminary discussion (see also 6), the
drawings of the building should give the following
particulars and finished sizes:
a) Number, type and size of lifts and position of
lift well;
b) Particulars of lift well enclosure;
c) Size, position, number and type of landing
doors;
10
NATIONAL BUILDING CODE OF INDIA
d) Number of floors served by the lift;
e) Height between floor levels;
f) Number of entrances;
g) Total headroom;
h) Provision of access to machine room;
j) Provision of ventilation and, if possible,
natural lighting of machine room;
k) Height of machine room;
m) Depth of lift pit;
n) Position of lift machine, above or below lift
well;
p) Size and position of any trimmer joists or
stanchions adjacent to the lift well at each
floor;
q) Size and position or supporting steel work at
roof levels;
r) Size and position of any footings or grillage
foundations, if these are adjacent to the lift
pit; and
s) In the case of passenger lifts whether the lift
cage is required to carry household luggage,
such as refrigerator, steel almirah, etc.
3.2.2.1 The lift lobby should be designed appropriately
since this has bearing on the traffic handling especially
when more number of lifts are involved. In a dual line
arrangement (lifts opposite to each other) the lobby
can be between 1 .5 times to 2.5 times the depth of one
car. Typically, the more the number of lifts the bigger
the multiple to be used. As an example a quadruplex
may use 1 .5 to 2 times where as an octoplex will need
2 to 2.5 times. For in-line (single line) arrangements,
the lobby can be typically half of the above
recommendations.
It is preferable that the lift lobby is not used as a
thoroughfare but in such cases the lift corridor shall
take into account space for people who are moving.
3.2.2.2 The architect/engineer should advise the lift
manufacturer, if the Authority has any special
requirements regarding lifts in buildings in the
administrative area concerned.
3.2.2.3 The information contained under 3.2.1
and 3.2.2 is applicable for the installation of lifts only
and in the case of escalator installations, the drawings •
shall provide the appropriate information.
3.2.2.4 The architect/engineer should inform the lift/
escalator manufacturer of the dates when the erection
of the lift/escalator may be commenced and is to be
completed so that sufficient time is allowed for the
manufacture and erection of the lift/escalator.
3.2.2.5 When submitting application for a building
permit to the local Authority, the building plans shall
include the details of lifts (number of lifts duly
numbered, location, type, type of doors, passenger
capacity and speed).
3.2.3 Working Drawings to be Prepared by the Lift/
Escalator Manufacturer
The lift/escalator manufacturer requires sufficient
information for the preparation of working drawings
and is usually obtained from architect* s drawings
supplemented by any information obtained from the
site and by collaboration with the other contractors.
3.2.3.1 Working drawings showing the layout of lift/
escalator duly numbered, details of builders work, for
example, holes in walls for guide fixing, holes in
machine room floor for ropes and conduits, recesses
for landing sills, supports for lift/escalator machine and
loads imposed on the building should be submitted by
the lift/escalator manufacturer to the architect/engineer
for written approval.
3.3 Electrical Requirement
For information of the electrical engineer, the lift/
escalator manufacturer should advise the architect/
engineer of his electrical requirements. This information
should be available early in the planning stage so that
the electrical supply requirements of the lift(s)/
escalator(s) may be included in the electrical provisions
of the building and that suitable cables and switchgear
may be provided.
3.4 The requirements given under 4 to 13 deal with
installation of lifts and 14 deal with the installation of
escalators.
4 ESSENTIAL REQUIREMENTS
4.1 Conformity with Lifts Act and Rules
The installation shall be generally carried out in
conformity with Lifts Act and Rules thereunder,
wherever they are in force.
4.1.1 It is the responsibility of the owner of the
premises where the lift will be installed, to obtain
necessary permission from the Authority before and
after the erection of lifts a#d for subsequent operation
oflift(s).
4.2 Conformity with Indian Electricity Act and
Rules
All electrical work in connection with installation of
electric lifts shall be carried out in accordance with
the provisions of The Indian Electricity Act, 2003 and
the provisions framed thereunder as amended from
time to time, and shall also comply with the other
provisions of Part 8 'Building Services, Section 2
Electrical and Allied Installations'.
PART 8 BUILDING SERVICES — SECTION 5 INSTALLATION OF LIFTS AND ESCALATORS
11
4.3 Conformity with Indian Standards
4.3.1 All materials, fittings, appliances etc used in
electrical installation shall conform to Indian Standard
specifications wherever these exist. In case of materials
for which Indian Standard specifications do not exist,
the materials shall be approved by the competent
authority. For detailed specification for lifts, reference
shall be made to accepted standards [8-5(2)].
4.4 Conformity with Fire Regulations
4.4.1 The installation shall be carried out in conformity
with Part 4 Tire and Life Safety' and local fire regulations
and rules thereunder wherever they are in force.
4.5 Factor of Safety
The minimum factor of safety for any part of the lift
shall not be less than five. Higher factor of safety for
various parts shall be applicable in accordance with
accepted standards [8-5(3)].
4.6 Additional Requirements for Passenger and
Goods Lifts
4.6.1 Bottom and Top Car Clearances
4.6.1.1 Bottom car clearance
When the car rests on its fully compressed buffer there
shall be a vertical clearance of not less than 600 mm
between the pit floor and the buffer striker plate or the
lowest structural or mechanical part equipment or
device installed. The clearance shall be available
beneath the whole area of the platform except for:
a) guide shoes or rollers, safety jaw blocks,
platform aprons, guards of other equipment
located within 300 mm measured horizontally
from the sides of the car platform; and
b) compensating sheaves.
Provided that in all the cases, including small cars, a
minimum clearance of 600 mm is available over a
horizontal area of 800 mm x 500 mm.
Provided also that in all the cases, when the car rests on
its fully compressed buffers, there shall be a vertical
clearance of not less than 50 mm between any part of
the car and any obstruction of device mounted in the
pit.
4.6.1.2 Top car clearance
The vertical clearance between the car cross-head and
the nearest overhead obstruction within 500 mm
measured horizontally to the nearest part of the
crosshead when the car platform is level with the top
landing, shall be not less than the sum of the following;
a) The bottom counterweight runby.
b) The stroke of the counterweight buffer used.
c) One-half of the gravity stopping distance
based on:
1 ) 115 percent of the rated speed where oil
buffers are used and no provision is
made to prevent the jump of the car at
counterweight buffer engagement; and
2) Governor tripping speed where spring
buffers are used.
NOTE — The gravity stopping distance based on
the gravity retardation from any initial velocity may
be calculated according to the following formula
S = 51 V 2
where
S = Free fall in mm (gravity stopping
distance), and
V = Initial velocity in m/s
d) 600 mm.
Where there is a projection below the ceiling of the
well and the projection is more than 500 mm, measured
horizontally from the centre line of the cross-head but
over the roof of the car, a minimum vertical clearance
not less than that calculated above shall also be
available between the roof of the car and the projection.
Provided that the vertical clearance between any
equipment mounted on top of the car and the nearest
overhead obstruction shall be not less than the sum of
the three items (a), (b) and (c) as calculated above plus
150 mm.
4.6.2 Bottom Runby for Cars and Counterweights
4.6.2.1 The bottom runby of cars and counterweights
shall be not less than the following:
a) 150 mm where oil buffers are used;
b) Where spring-buffers are used;
1) 150 mm for controls as in 2.12.4 to 2.12.8.
2) Not less than the following for controls
as in 2.12.2 to 2.12.3.
Rated speed Runby
m/s mm
Up to 0.125 75
0.125 to 0.25 150
0.25 to 0.50 225
0.50 to 1 300
4.6.3 Maximum Bottom Runby
In no case shall the maximum bottom runby exceed
the following:
a) 600 mm for cars; and
b) 900 mm for counterweights.
4.6.4 Top Counterweight Clearances
The top counterweight clearance shall be not less than
the sum of the following four items:
a) the bottom car runby;
12
NATIONAL BUILDING CODE OF INDIA
b) the stroke of the car buffer used;
c) 150 mm; and
d) one-half the gravity stopping distance based
on
1) one hundred and fifteen percent of the
rated speed where oil buffers are used and
no provision is made to prevent jump
of the counterweight at car buffer
engagement; and
2) governor tripping speed where spring
buffers are used.
4.7 Additional Requirements for Service Lifts
4,7.1 Top and Bottom Clearances for Car and
Counterweights
4.7.1.1 Top car clearance
The top car clearance shall be sufficient to avoid any
protruding part fixed on the top of the car coming in
direct contact with the ceiling or diverting sheave.
The clearance shall be calculated taking into account
the following and shall not be less than the sum of the
following four items:
a) The bottom counterweight runby,
b) The stroke of the counterweight buffer
used,
c) The dimensions of the portion of the diverting
sheave hanging underneath the ceiling in the
lift well, and
d) 1 50 mm for compensating for gravity stopping
distance and future repairs to the rope
connections at counterweight and at the car
or at the suspension points.
4.7.1.2 Bottom car clearance
The bottom car clearance shall be maintained in such
a way that the counterweight shall not come in contact
with the ceiling or any part hanging underneath the
ceiling, when the car completely rests on fully
compressed buffers, provided the buffers are spring
type mounted on solid concrete or steel bed.
In case of wooden buffers the bottom car clearance
shall be maintained in such a way that the total
downward travel of the car from the service level of
the immediate floor near the pit, shall not be more than
the top counterweight clearance, when the wooden
buffers are completely crushed.
4.7.1.3 Top counterweight clearance
The top clearance for the counterweight can be
calculated taking into account the following and shall
not be less than the sum of the following three items:
a) Car runby,
b) Compression of the buffer spring or height
of the wooden block used as buffer, and
c) 150 mm to compensate for gravity stopping
distance for counterweight and any
future repairs to rope connections at the
counterweight at the car ends or at the
suspension points.
4.7.1.4 Runby for Cars and Counterweights
The bottom runby for cars and counterweights shall
not be less than 150 mm.
4.7.1.5 Maximum bottom runby
In no case shall the maximum bottom runby exceed
300 mm.
4.8 In order to maintain a safe work environment, and
to avoid potential hazards, the following shall be
provided:
a) caution sign shall be installed in the areas
listed below where potential hazard exists:
1) Trip hazard in machine room; and
2) Caution notice against unauthorized use
of rescue devices (for example, brake
release device).
b) Use the hard hats for entry in pit and car top
during construction period.
c) Warning sign shall be provided on the
controller so also eliminate, the possibility of
contact with any exposed or concealed power
circuit.
d) Car top barricade system shall be provided
as primary protection against fall, on car
top.
e) Whenever work is carried out on the lift and
lift is not required to be moved on power,
notice shall be put on electrical main switch
indicating requirement of de-energized
condition.
f) During lift installation/maintenance, protection
against fall shall be provided with suitable
barricades for all open lending entrances.
4.9 Planning for Dimensions
4.9.1 General
The dimensions of lift well have been chosen to
accommodate the doors inside the well which is the
normal practice. In special cases, the door may be
accommodated in a recess in the front wall, for which
prior consultation shall be made with the lift
manufacturer.
4.9.2 Plan Dimensions
4.9.2.1 All plan dimensions of lift well are the
PART 8 BUILDING SERVICES — SECTION 5 INSTALLATION OF LIFTS AND ESCALATORS
13
minimum clear plumb sizes. The architect/engineer,
in conjunction with the builder, shall ensure that
adequate tolerances are included in the building design
so that the specified minimum clear plumb dimensions
are obtained in the finished work.
NOTE — The words 'clear plumb dimensions' should be noted
particularly in case of high rise buildings.
4.9.2.2 Rough opening in concrete or brick walls to
accommodate landing doors depend on design of
architrave. It is advisable to provide sufficient
allowances in rough opening width to allow for
alignment errors of opening at various landings.
4.9.2.3 When more than one lift is located in a
common well, a minimum allowance of 100 mm for
separator beams shall be made in the widths shown in
Tables 1 to 4.
4.9.2.4 Where the governor operated counterweight
safety is required under conditions stipulated in good
practice [8-5(3)], the tabular values should be revised
in consultation with the lift manufacturer.
4.9.2.5 For outline dimensions of lifts having more
than one car entrance, lift manufacturers should be
consulted.
4.9.3 Outline Dimensions
4.9.3.1 The outline dimensions of machine-room, pit
depth, total headroom, overhead distance and sill for
four classes of lifts to which the standard applies are
specified in Tables 1 to 4 as indicated below:
Passenger lifts
Table 1 and 1A
Goods lifts
Table 2
Hospital lifts
Table 3
Service lifts
Table 1 and 1A
Dumb Waiter
Table 4
Table 1 Recommended Dimensions of Passenger Lifts and Service Lifts
(Clauses 4.9.2.3 and 4.9.3.1)
All dimensions in millimetres.
i — 50 min.
WINDOW
i
HOISTING
BEAMS/HOOKS
TERRACE
LEVEL""
j — 150
2000 min.
ENTRANCE
L_
TRAP
DOOR-<
li
i?
OVERHEAD
L
TOP
LANDING
St.
i ,, SILL PROJECTION
RCC / STEEL
BOTTOM
LANDING "
TRAVEL
PIT
DEPTH
MACHINE
ROOM
DEPTH
ELEVATION
PLAN
14
NATIONAL BUILDING CODE OF INDIA
Table 1 — Concluded
Load
-a.
<
Car Side
]
Lift Wei
1
Entrance
•"■'
^N
~"S
Persons
kg
A
B
c
D
E
(1)
(2)
(3)
(4)
(5)
(6)
(7)
4
272
1100
700
1900
1300
700, Mm
6
408
1100
1000
1900
1700
700,A/in
8
544
1300
1100
1900
1900
800
10
680
1300
1350
1900
2100
800
13
884
2000
1 100
2 500
1900
900
16
1088
2000
1300
2 500
2100
1000
20
1360
2000
1500
2 500
2 400
1000
Table 1 A Recommended Dimensions of Pit, Overhead and Machine-Room
for Passenger Lifts and Service Lifts
(Clauses 4.9.2.3 and 4.9.3.1)
All dimensions in millimetres.
Speed in m/s
0)
Up to 0.70
(2)
> 0.70 < 1.00
(3)
> 1.00 < 1.50
(4)
> 1.50 < 1,75
(5)
> 1.75 < 2,00
(6)
> 2.00 £ 2.50
(7)
Pit depth
1350
1500
1600
2 150
2 200
2 500
Overhead
4 200
4 250
4 800
4 800
5 200
5 400
Machine-room
D + 2000
D+2500
Depth
Machine-room
C+1000
C+ 1200
C+1500
Width
NOTES
1 The total overhead dimension has been calculated on the basis of car height of 2.3 m.
2 In case of manually operated doors, clear entrance will be reduced by the amount of projection of handle on the landing door.
3 All dimensions given above for lifts having centre opening power operated doors with counterweight at rear, are recommended
dimensions primarily for architects and building planners. Any variations mutually agreed between the manufacturer and the purchaser
are permitted. However, variation in:
a) Car inside dimensions shall be within the maximum area limits specified in accordance with accepted standards [8-5(4)].
b) Entrance width on higher side is permitted.
c) Entrance width on lower side is permitted up to 100 mm subject to minimum of 700 mm.
4 Dimensions of pit depth and overhead may differ in practice as per individual manufacturer's design depending upon load, speed
and drive. Recommended dimensions for pit depth, overhead and machine-room for different lift speeds are given in Table 1A.
However, the pit depth and overhead shall be such as to conform to the requirements of bottom clearance and top clearance in
accordance with the accepted standards [8-5(5)].
PART 8 BUILDING SERVICES — SECTION 5 INSTALLATION OF LIFTS AND ESCALATORS
15
Table 2 Recommended Dimensions of Goods Lifts
(For Speeds Up to 0.5 m/s)
(Clauses AS 23 and 4.9 '.3 .1)
All dimensions in millimetres.
2500
r
!
i
#n-i'
I 300
U £ J
-A-
-e-
F
SILL 150
L L
R"~"7I
i x/ i
4
-MACHINE ROOM = C + 2000-
PLAN
t Q
2
8
g:
ID
z
X
o
ELEVATION
Load
kg
(1)
Car Inside
Lift WeH
A
(2)
(3)
c
D
(4)
(5)
1900
1500
2 300
2100
2600
2 300
2600
2 800
2 900
2 800
2900
3 300
3 400
3 300
3 400
3 900
Entrance
E
(6)
500
1000
1500
2000
2 500
3 000
4000
5 000
1 100
1400
1700
1700
2000
2000
2 500
2 500
1200
1800
2000
2 500
2 500
3000
3000
3 600
1100
1400
1700
1700
2000
2000
2 500
2 500
NOTES
1 The width of machine room shall be equal to be lift well width *C* subject to minimum of 2 500 mm.
2 The total headroom has been calculated on the basis of a car height of 2.2 m.
3 Clear entrance width *£' is based on vertical lifting car-door and vertical biparting landing doors. For collapsible mid-bar doors the
clear entrance width will be reduced by 200 mm (maximum 1 800 mm).
4 All dimensions given above are recommended dimensions primarily for architects and building planners. Any variations mutually
agreed between the manufacturer and the purchaser are permitted. However, variation in car inside dimensions shall be within the
maximum area limits in accordance with accepted standards [8-5(4)].
5 Dimensions of pit depth and overhead may differ in practice as per individual manufacturer's design depending upon load, speed
and drive. However, the pit depth and overhead shall be such as to conform to the requirements of bottom clearance and top clearance
in accordance with accepted standards [8-5(5)].
16
NATIONAL BUILDING CODE OF INDIA
Table 3 Recommended Dimensions of Hospital Lifts
(For Speeds Up to 0.5 m/s)
(Clauses A3. 23 and 4.9.3.1)
All dimensions in millimetres.
PLAN
ELEVATION
Load
Car Inside
lift Well
Persons
(1)
kg
(2)
A
(3)
B
(4)
C
(5)
b
(6)
15
20
26
1020
1360
1768
1000
1300
1600
2400
2 400
2 400
1800
2200
2400
3dpp
30*
3000
Entrance
E
(7)
800
1200
1200
NOTES
1 The total headroom has been calculated on the basis of a car height of 2.2 m.
2 In the case of manually -operated doors, clear entrance will be reduced by the amount of projection of handle on the landing door.
3 Although 15 persons capacity lift is not standard one, this is included to cover lifts of smaller capacity which can be used in small
hospitals.
4 All dimensions given above are recommended dimensions primarily for architects and building planners. Any variations mutually
agreed between the manufacturer and the purchaser are permitted. However, variation in car inside dimensions shall be within the
maximum area limits in accordance with accepted standards [8-5(4)].
5 Dimensions of pit depth and overhead may differ in practice as per individual manufacturer's design depending upon load, speed
and drive. However, the pit depth and overhead shall be such as to conform to the requirements of bottom clearance and top clearance
in accordance with accepted standards [8-5(5)].
PART 8 BUILDING SERVICES — SECTION 5 INSTALLATION OF LIFTS AND ESCALATORS
17
Table 4 Recommended Dimensions of Dumb Waiter
(For Speeds Up to 0.5 m/s)
(Clauses 4.9.2.3 and 4.9.3.1)
All dimensions in millimetres.
o
o
TOP LANDING
~~| (SERVICE LEVEL)
750
FLOOR LEVEL
I
BOTTOM LANDING
(SERVICE LEVEL)
ii
750
PLAN
ELEVATION
Load
kg
(1)
100
150
200
250
A
(2)
700
800
900
1000
Car Inside
B
(3)
700
800
900
1000
H
(4)
800
900
1000
1200
Lift Well
C
(5)
D
(6)
1200
1300
1400
1500
900
1000
1 100
1200
Entrance
E
(7)
700
800
900
1000
NOTE — Entrance width 'E is based on assumption of provision of vertical biparting doors (no car door is
normally provided).
18
NATIONAL BUILDING CODE OF INDIA
4.9.3.2 Travel
The tables have been established for a maximum travel
of 30 m. For travels above 30 m, the lift manufacturer
should be consulted.
4.9.3.3 Pit
The pit depth of the lifts will normally accommodate
compensating chains. If compensating ropes are
required, pit depth shall be increased for all loads and
speeds and lift manufacturer should be consulted.
4.9.3.4 Minimum floor to floor height
Minimum floor to floor height for landings on same
side for horizontally sliding door is / + 750 mm and
for vertically biparting doors is 1.5/+ 250 mm, where
'/' is clear entrance height in mm.
4.10 Lift Wells and Lift Well Enclosures
4.10.1 Lift Wells
4.10.1.1 No equipment except that forming a part of
the lift or necessary for its operation and maintenance
shall be installed in the lift well. For this purpose, the
main supply lines shall be deemed to be a part of the
lift and the underground cable, if laid along the lift
well shaft, shall be properly clamped to the wall.
4.10.1.2 Sufficient space shall be provided between
the guides for the cars and the side walls of the lift
well enclosure to allow safe and easy access to the
parts of the safety gears for their maintenance and
repairs; safety gears provided shall be in accordance
with good practices [8-5(3)].
4.10.1.3 Lift wells, together with the whole of the
contained equipment and apparatus, shall be rendered fire
resistant to the greatest possible extent {see also 4.4.1).
4.10.1.4 Every counterweight shall travel in juxtaposition
to its car in the same lift welL
4.10.1.5 It is undesirable that any room, passage or
thoroughfare be permitted under any lift well. If
unavoidable spaces for other uses may be permitted
under the lift well, with the prior approval of the Lift
Inspectorate Authority and the following provisions
shall be made:
a) Spring or Oil buffers shall be provided for
lift car and counterweight;
b) The pit shall be sufficiently strong to
withstand successfully the impact of the lift
car with rated load or the impact of the
counterweight when either is descending at
rated speed or at governor tripping speed;
c) The car and the counterweight shall be
provided with a governor-operated safety
gear; and
d) The forces required on the structure in the
event of car buffering directly without safety
gear application to be indicated in the general
arrangement drawing.
4.10.2 Lift Well Enclosures
4.10.2.1 Lift well enclosures shall be provided and
shall extend on all sides from floor-to-floor or stair-
to-stair, and shall have requisite strength and in proper
plumb.
4.10.2.2 The inner sides of the lift well enclosures
facing any car entrance shall, as far as practicable form
a smooth, continuous flush surface devoid of
projections or recesses.
NOTE — This requirement may be met in existing lift wells by
filling any recesses or spaces between projections or alternatively
by covering them with suitable sheet material. If it is not possible
to render flush any objection or tops of recesses, they should be
beveled on the under side to an angle of 60°, from the horizontal
by means of metal plates, cement rendering or other fire-resisting
materials. Where a car-levelling device is operative with car
door opening, such interior surfaces shall always form a smooth
flush surface below each landing level for a depth to at least the
depth of the car-levelling zone plus the distance through which
the lift car may travel of its own momentum when the power is
cut-off.
4.10.2.3 Where an open lift well would increase the fire
risk in a building, the lift well enclosure shall be of fire-
resisting construction {see Part 4 Tire and Life Safety').
4.10.2.4 Where wire grill or similar constructions is
used, the mesh or opening shall be such that the
opening between the bars shall reject the ball of 30 mm
in diameter and the lift well enclosure shall be of
sufficient strength to resist accidental impact by users
of the staircase or adjoining floors or by materials or
trucks being moved in the vicinity.
4.10.2.5 Where the clearance between the inside of
an open-type lift well enclosure and any moving or
movable part of the lift equipment of apparatus is less
than 50 mm, the openings in the enclosure shall be
further protected by netting of square mesh of aperture
not greater than one centimeter and of wire not smaller
than one mm. (The provisions of this clause need not
be adhered to for lift wells iff factory premises, coming
under the purview of Factories Act. In such cases
provisions of 4.10.2.4 is sufficient)
4.10.2.6 There shall be no opening in the lift well
enclosure permitting access to the lift car by passing
under the counterweight.
4.10.2.7 In case of a completely enclosed lift well, a
notice with the word 'Lift' may be placed outside of
each landing door.
4.10.2.8 Indicator
Where lifts are installed in totally enclosed wells,
PART 8 BUILDING SERVICES — SECTIONS INSTALLATION OF LIFTS AND ESCALATORS
19
position indicators are recommended to be provided
at each floor; however, where position indicators are
not provided, at least direction indicators or 'In Use*
indicators shall be provided at each landing.
4.10.2.9 Landing doors
Every lift well shall, on each side from which there is
access to a car, be fitted with a door. Such a door shall
be fitted with efficient electromechanical locking so
as to ensure that it cannot be opened except when the
lift car is at landing and that the lift car cannot be moved
away from the landing until the door is closed and
locked. If the door is mechanically locked, means
should be provided for opening the same by means of
special key during emergency or inspection.
4.10.2.10 Automatic devices for cutting off power
An efficient automatic device shall be provided and
maintained in each lift whereby all power shall be cut
off from the motor before the car or counterweight
lands on buffer.
4.10.3 Lift Pits
4.10.3.1 A lift pit shall be provided at the bottom of
every lift.
4.10.3.2 Pits shall be of sound construction and
maintained in a dry and clean condition. Where
necessary, provision shall be made for permanent
drainage and where the pit depth exceeds 1 .5 m suitable
descending arrangement shall be provided to reach the
lift pit. And a suitable fixed ladder or other descending
facility in the form of permanent brackets grouted in
the wall extending to a height of 0.75 m above the
lowest floor level shall be provided. A light point with
a switch shall also be provided for facility of
maintenance and repair work.
4.11 Machine Rooms and Overhead Structures
4.11.1 The lift machine, controller and all other
apparatus and equipment of a lift installation, excepting
such apparatus and equipment as function in the lift
well or other positions, shall be placed in the machine
room which shall be adequately lighted and rendered
fire-proof and weather-proof.
4.11.2 The motor generators controlling the speed of
multi-voltage or variable voltage machines, secondary
sheaves, pulleys, governors, floor selecting equipment
may be placed in a place other than the machine room,
but such position shall be adequately lighted, ventilated
and rendered fire-proof and weather-proof.
4.11.3 The machine room shall have sufficient floor
area as well as permit free access to all parts of the
machines and equipment located therein for purposes
of inspection, maintenance or repair.
4.11.4 The room shall be kept closed, except to those
who are concerned with the operation and maintenance
of the equipment. When the electrical voltage exceeds
220/230 V ac, a danger notice plate shall be displayed
permanently on the outside of the door and on or near
the machinery. Where standby generator is provided,
it is necessary to connect fireman lift to the standby
generator. Depending upon the capacity of the standby
generator one or more other lifts may also be connected
to the supply.
Rescue instruction with required tools and tackles if
any shall be made available in the machine room.
All lifts which do not have any automatic transfer
facility to an alternate supply, such as generators, shall
be equipped with Battery Operated Automatic Rescue
Device to bring the lift to the nearest floor and open
the door in the event of power failure.
4.11.5 The machine room shall be equipped with an
insulated portable hand lamp provided with flexible
cord for examining the machinery.
4.11.6 If any machine room floor or platform does
not extend to the enclosing walls, the open sides shall
be provided with hand rails or otherwise suitably
guarded.
4.11.7 The machine room shall not be used as a store
room or for any purpose other than housing the lift
machinery and its associated apparatus and equipment.
4.11.8 Machine room floor shall be provided with a
trap door, if necessary. The size of the trap door shall
be as per manufacturer's recommendation.
4.11.9 The height of the machine room shall be
sufficient to allow any portion of equipment to be
accessible and removable for repair and replacement
and shall be not less than 2 m clear from the floor or
the platform of machine whichever is higher.
4.11.10 It will be noted that generally lifts have
machine rooms immediately over the lift well, and this
should be arranged whenever possible without
restricting the overhead distance required for normal
safety precautions. In qase where machine room
provision on top is a limitation, either machine room
less lift or basement drive or side drive lift can be
considered.
4.11.11 For detailed irrformation regarding nomenclature
of floors and storeys, reference may be made to good
practice [8-5(6)].
4.11.12 There should be a proper access planned for
approach to the machine room taking into account need
for maintenance personnel to access the machine room
at all times of day and night and also the need to take
heavy equipment. Any fixture such as a ladder
20
NATIONAL BUILDING CODE OF INDIA
provided should be secured permanently to the
structure and should have railings to reduce the risk of
falling,
4.11.13 It is desirable that emergency exit may be
provided in case of large machine rooms having four
or more lifts.
4.11.14 Where the machine room occupies a prominent
position on roof of a building, provision should be
made for lightning protection in accordance with good
practice [8-5(7)] and Part 8 'Building Services,
Section 2 Electrical and Allied Installations' .
4*11.15 Wherever the machine room is placed, it
should be properly ventilated. The ambient temperature
of machine room shall be maintained between + 5°C
and + 40°C.
4.11.16 If located in the basement, it should be
separated from the lift well by a separation wall.
4.12 Essentia] Features Required
4.12.1 Power operated car doors on automatically
operated lifts shall be so designed that their closing
and opening is not likely to injure a person. The power
operated car door shall be provided with a sensitive
device which shall automatically initiate reopening of
the door in the event of a passenger being struck or is
about to be struck by the door, while crossing the
entrance during closing movement. The effect of the
device may be neutralized:
a) during the last 58 mm of travel of door panel
in case of side opening doors
b) when panels are within 58 mm of each other
in case of center opening doors.
The force needed to prevent the door from closing shall
not exceed 150 N and this measurement shall not be
made in the first third of the travel of the door.
In order to achieve this it is desirable that all power
operated doors have a full length (covering at least 80
percent of the car door height from the bottom) infra
red light curtain safety to retract the door in the event of
coming across any obstacle during closing of the door.
4.12.2 Single speed and two speed drives which are
poor in levelling accuracy and energy consumption
shall not be used for new lifts in view of availability of
latest technology energy efficient Variable Voltage
Variable Frequency drive systems with improved
leveling accuracy.
4.12.3 For passenger lifts with car call button control
in car and with capacities of 16 passenger and above,
it is recommended to have an additional car operating
panel with call buttons on the opposite side to main
panel for ease of access to buttons.
4.12.4 Passenger lifts shall be provided with power
operated doors which are imperforate.
5 DIMENSIONAL TOLERANCES
5.1 Lift Well Dimensions
Plan dimensions of lift wells given by the lift maker
represent the minimum clear plumb sizes. The
purchaser's representative, in conjunction with the
builder, should ensure that adequate tolerances are
included in the building design so that the specified
minimum plumb dimensions are obtained in the
finished work.
Dimensions in excess of these minimum plumb
dimensions for lift well and openings (but not less)
can be accommodated by the lift maker up to certain
maximum values beyond which changes in design
may be necessary involving additional expense or
work by the builder. The purchaser's representative
should take these factors into account when
specifying the lift well structural dimensions on the
basis of the constructional tolerance appropriate to
the building technique.
5.2 Landing Door Openings
It is very important that finished landing openings
should be accurate to design size and plumb one above
the other for the full travel of the lift. In constructing
the structural openings in concrete walls to lift wells it
is not possible to achieve a degree of accuracy
vertically which will allow doors and frames to be
inserted in the opening without some form of masking
or packing to overcome inaccuracies. Provisions
should therefore be made in design by increasing the
nominal height from design finished floor level and
width of openings to each jamb and head.
In addition, the alignment of the outer face of the front
wall of the lift well is of importance when architrave
of fixed dimensions are called for, and in this case the
alignment of the outer face from floor to floor should
not vary to a greater extent than can be accommodate
by the subsequent front wall finish, the architrave being
set accurately plumb.
To facilitate accurate alignment of landing sills it is
common practice to provide at each landing an
independent threshold, the position of which can be
adjusted.
5.3 Structural Limits for Lift Wells at any Level
If the net plumb well (dimensions A and B of Fig. 2)
and the nominal structural entrance openings
(dimensions C and D of Fig. 2) are defined by plumb
lines, the actual wall should not encroach on these
dimensions.
PART 8 BUILDING SERVICES — SECTION 5 INSTALLATION OF LIFTS AND ESCALATORS
21
Dimension K (inside face of wall of Fig. 2) should fall
within the following limits:
For wells upto 30 m - 0-25 mm
For wells upto 60 m - 0-35 mm
For wells upto 90 m - 0-50 mm
When architrave are to be supplied by the lift maker
dimension L (side of structural opening of Fig. 2)
should fall within the limits of and 25 mm and
dimension M (outer face of the front wall of Fig. 2)
should not vary to a greater extent than can be
accommodated by the subsequent front wall finish, the
architrave being set accurately plumb.
When the entrance linings are supplied by the builder,
corresponding provision should be made for the
finished openings to be accurately plumb one above
the other for the full travel of the lift end to design
size.
Fig. 2 Life Well Tolerance
6 PRELIMINARY DESIGN
6.1 Number of Lifts and Capacity
6.1.1 Two basic considerations, namely, the quantity
of service required and the quality of service desired,
determine the type of lifts to be provided in a particular
building. Quantity of service gives the passenger
handling capacity of the lifts during the peak periods
and the quality of service is measured in terms of
waiting time of passengers at various floors. Both these
basic factors require proper study into the character of
the building, extent and duration of peak periods,
frequency of service required, type and method of
control, type of landing doors etc. In busy cities
patience, coefficient being low satisfaction cannot be
obtained if lifts with adequate capacities and speeds
are not provided. In view of many variables, no simple
formula is possible for determining the most suitable
lifts.
NOTE — It is recommended to do Traffic Analysis Study to
ensure optimum provision of lifts for the building in consultation
with lift manufacturers. In view of the dynamic situation it is
recommended that a computerised software is used for Traffic
Analysis Study.
6.1.2 The number of passenger lifts and their
capacities, that is load and speed, required for a given
building depend on the characteristics of the building.
The most important of these are:
a) Number of floors to be served by the lift;
b) Floor to floor distance;
c) Population of each floor to be served; and
d) Maximum peak demand; this demand may be
unidirectional, as in up and down peak
periods, or a two-way traffic movement.
It should be appreciated that all calculations on the
traffic handling capabilities of lifts are dependent on a
number of factors which vary according to the design
of lift and the assumptions made on passenger actions.
It follows, therefore, that the result of such calculations
can only be put to limited use of a comparative nature.
For instance, they can with advantage be used to
compare the capabilities of lifts in a bank with different
loads and speeds provided the same set of factors are
used for all cases. On the other hand, they cannot be
used to compare the capabilities of different makes of
lift used for a given bank of lifts.
Different authorities and manufacturers differ widely
in their methods of calculation, due to the variations
in lift performance, especially with regard to rates of
acceleration and deceleration and door operation times
which form the components of performance time.
Therefore, the calculations made by different
organizations will not necessarily agree.
6.2 Preliminary Lift Planning
6.2.1 General
Methods of calculating the traffic handling capabilities
of lifts were first devised for office buildings. In due
course detailed modifications were devised to suit other
applications without altering the basic principles. The
application to office buildings is still the most
frequently used.
Therefore, the following method may be used as
general guidance on preliminary lift planning for
offices, bearing in mind the differences set out
in 6.1.2.
A lift installation for office building is normally
designed to populate the building at a given rate and
the three main factors to be considered are:
a) population or the number of people who
require lift service.
22
NATIONAL BUILDING CODE OF INDIA
b) handling capacity of the maximum flow rate
required by these people.
c) interval or the quality of service required.
6.2.2 Population
The first point to be ascertained from the eventual
occupier is the total building population and whether
this is likely to increase in the future.
If a definite population figure is unobtainable an
assessment should be made from the net area and
probable population density. Average population
density can vary from about one person per 4 m 2 to
one person per 20 m 2 . It is essential, therefore, that
some indication of the probable population density
should be obtained from the building owner. If no
indication is possible (a speculative development for
example) population in the region of 5 m 2 per person
for general office buildings is usually assumed.
6.2.3 Quantity of Service
The quantity of service is a measure of the passenger
handling capacity of a vertical transportation system.
It is measured in terms of the total number of
passengers handled during each five-minute peak
period of the day. A five-minute base period is used as
this is the most practical time over which the traffic
can be averaged.
The recommended passenger handling capacity for
various buildings is as follows:
Type of Building
Handling Capacity
Office — Diversified tenants
10 to 15 percent
Office — Single tenant
15 to 25 percent
Residential
7.5 percent
6.2.4 Quality of Service
The quality of service on the other hand is generally
measured by the passenger waiting time at the various
floors. The following shall be the guiding factor for
determining this aspect.
Quality of Service or Acceptable Interval
20 to 25 seconds
Excellent
30 to 35 seconds
Good
34 to 40 seconds
Fair
45 seconds
Poor
Over 45 seconds
Unsatisfactory
NOTE — For residential buildings longer intervals should
be permissible.
6.2.5 Traffic Peaks
The maximum traffic flow during the up peak period
is usually used as a measure of the vertical transportation
requirement in an office building. The employees of
all offices are subject to discipline and are required to
be at their place in time. Consequently, the incoming
traffic flow is extremely high and the arrival time is
over a short period.
Sometimes it becomes necessary to reduce the
maximum traffic flow by staggering the arrival of the
employees so that different groups arrive at different
times. This reduces the peak and also the requirement
of lifts. However, many organizations may object to
staggering and prefer to have all employees arrive at
the same time since it is claimed that staggering will
affect the proper co-ordination of business.
6.2.6 Capacity
The minimum size of car recommended for a single
purpose buildings is one suitable for a duty load of
884 kg. Generally, for large office buildings cars with
capacities up to 2 040 kg are recommended according
to the requirements.
6.2.7 Speed
It is dependent upon the quantity of service required
and the quality of service desired (see 6.2.3 and 6.2.4).
Therefore, no set formulae for indicating the speed
can be given. However, the following general
recommendations are made:
No. of Floors
Speed
4 to 5
0.5 to 0.75 m/s
6 to 12
0.75 to 1.5 m/s
3 to 20
1.5 m/s to 2.5 m/s
Above 20
2.5 m/s and above
6.2.8 Layout
The shape and size of the passenger lift car bears a
distinct relation to its efficiency as a medium of traffic
handling. A study of the most suitable proportions for
these lifts reveal that the width of the lift well entrance
is in reality, the basic element in the determination of
the best proportions. In other words, the width of the
car is determined by the widjh of the entrance and the
depth of the car is regulated by the loading per square
metre permissible under this Code. Centre opening
doors are more practicable and efficient entrance units
for passenger lifts.
6.2.9 Determination of Transportation or Handling
Capacity During the Up Peak
6.2.9.1 The handling capacity is calculated by the
following formula:
H =
300x6x100
TxP
PART 8 BUILDING SERVICES — SECTION 5 INSTALLATION OF LIFTS AND ESCALATORS
23
where
H = Handling capacity as the percentage of the
peak population handled during 5 min
period,
Q = Average number of passengers carried in a
car,
T = Waiting interval in seconds, and
P = Total population to be handled during peak
morning period. (It is related to the area
served by a particular bank of lifts.)
The value of Q depends on the dimensions of the car.
It may be noted that the car is not loaded always to its
maximum capacity during each trip and, therefore, for
calculating H the value of Q is taken as 80 percent of
the maximum carrying capacity of the car.
The waiting interval is calculated by the following
formula:
T =
RTT
N
where
T = Waiting interval in seconds,
TV = Number of lifts, and
RTT~ Round trip time, that is, the average time
required by each lift in taking one full
load of passengers from ground floor,
discharging them in various upper floors
and coming back to ground floor for taking
fresh passengers for the next trip,
RTT is the sum of the time required in the following
process:
a) Entry of the passengers on the ground floor,
b) Exit of the passengers on each floor of
discharge,
c) Door closing time before each starting
operation,
d) Door opening time on each discharging
operation,
e) Acceleration periods,
f) Stopping and levelling periods,
g) Periods of full rated speeds between stops
going up, and
h) Periods of full rated speeds between stops
going down.
It is observed that the handling capacity is inversely
proportional to waiting interval which in turn is
proportional to RTT. Reducing the RTT of a lift from
120 to 100 increases its handling capacity by
20 percent.
The round trip time can be decreased not only by
increasing the speed of the lift but also by improving
the design of the equipment related to opening and
closing of the landing and car doors, acceleration,
deceleration, levelling and passenger movement. These
factors are discussed below:
a) The most important factor in shortening the
time consumed between the entry and the exit
of the passengers to the lift car is the correct
design of the doors and the proper car width.
For comfortable entry and exit for passengers
it has been found that most suitable door
width is 1 000 mm and that of car width is
2 000 mm.
b) The utilization of centre opening doors has
been a definite factor in improving passenger
transfer time, since when using this type of
door the passengers, as a general rule, begin to
move before the doors have been completely
opened. On the other hand, with a side
opening door the passengers tend to wait until
the door has completely opened before
moving.
The utilization of centre opening doors also favours
the door opening and closing time periods. Given the
same door speed, the centre opening door is much
faster than the side opening type. It is beyond doubt
that the centre opening door represents an increase in
transportational capacity in the operation of a lift.
6.2.9.2 An example illustrating the use of the above
consideration is given below:
Gross area per floor 1 100 m 2
Net usable area per floor 950 m 2
No. of landings including 15
ground
Assuming population density 9.5 m 2 per person
Probable population in
P =
14x950
9.5
Upper floors
1 400 persons
Taking 20 passengers lift with
2.5 m/s the calculated RTT 165 s
Q = 20 x 0.8 = 16
a) Taking No. of lifts, N = 4
T =
RTT 165
N
= 41s
H
300x<3xl00 300x16x100
~ 41x1400
TxP
= 8.3 percent
b) Taking No. of lifts, N= 6
24
NATIONAL BUILDING CODE OF INDIA
^ 165
T=— = 27.6 s
o
_ 300xQxlOO _ 300x16x100
TxP ~ 27.6x1400
= 12 percent
6.3 Quiet Operation of Lifts
Every precaution should be taken with passenger lifts
to ensure quiet operation of the lift doors and
machinery. The insulating of the lift machine and any
motor generator from the floor by rubber cushions or
by a precast concrete slab with rubber cushions,
prevents transmission of most of the noise. In this
connection, see also good practice [8-5(8)] and Part 8
'Building Services, Section 4 Acoustics, Sound
Insulation and Noise Control* for some useful
recommendations .
6.4 Positioning of Lifts
A thorough investigation should be made for assessing
the most suitable position for lift(s) while planning the
building. It should take into account future expansions,
if any. Though each building has to be considered
individually for purposes of location of lifts, factors
influencing the locations of passenger and goods lifts
are given in 6.4.2 to 6.4.4,
The location of lifts may also conform to the travel
distance requirements specified in Part 4 'Fire and Life
Safety'.
6.4.1 Arrangement of Lifts
The lifts should be easily accessible from all entrances
to the building. For maximum efficiency, they should
be grouped near the centre of the building. It is preferably
not to have all the lifts out in straight line and, if possible,
not more than three lifts should be arranged in this
manner. It has to be kept in mind that the corridor should
be wide enough to allow sufficient space for waiting
passengers as well as for through passengers.
6.4.1.1 In some cases when there are more than three
lifts, the alcove arrangement is recommended. With
this arrangement, the lift alcove lead off the main
corridor so that there is no interference by traffic to
other groups or to other parts of the ground floor. This
arrangement permits the narrowest possible corridors
and saves space on the upper floors. Walking distance
to the individual lift is reduced and passenger standing
in the center of the group can readily see all the lift
doors and landing indicators. The ideal arrangement
of the lifts depends upon the particular layout of the
respective building and should be determined in
every individual case. Some typical recommended
arrangements are given in Fig. 1.
6.4.2 Passenger Lifts
6.4.2.1 Low and medium class flats
Where a lift is arranged to serve two, three or four
flats per floor, the lift may be placed adjoining a
staircase, with the lift entrances serving direct on to
the landings. Where the lift is to serve a considerable
number of flats having access to balconies or corridors,
it may be conveniently placed in a well ventilated tower
adjoining the building.
6.4.2.2 Office buildings, hotels and high class flats
In general the arrangement as recommended in 6.4.1
is to be followed. However, in case this is not possible,
it is desirable to have at least a battery of two lifts at
two or more convenient points of a building. If this is
not possible, it is advisable to have at least two lifts
side by side at the main entrance and one lift each
at different sections of the building for inter-
communication. When two lifts are installed side by
side, the machine room shall be suitably planned with
sufficient space for housing the machine equipment.
The positioning of lifts side by side gives the following
advantages:
a) all machines and switch gear may be housed
in one machine room,
b) the lifts can be inter-connected more
conveniently from an installation point of
view, and
c) greater convenience in service owing to the
landing openings and each floor being
adjacent.
6.4.2.3 Shops and departmental stores
Lifts in shops and stores should be situated so as to
secure convenient and easy access at each floor.
6.4.2.4 For buildings with more than 12 floors, it is
recommended to have provision of 1 stretcher/service
lift in addition to the passenger lifts.
6.4.2.5 For buildings with more than 12 floors, where
passenger and service lifts are provided in one lobby
it is recommended to have group control for all the
lifts.
6.4.3 Goods Lifts
The location of lifts in factories, warehouses and
similar buildings should be planned to suit the
progressive movement of goods throughout the
buildings, having regard to the nature of position of
the loading platforms, railway sidings, etc. The placing
of a lift in a fume or dust laden atmosphere or where it
may be exposed to extreme temperatures, should be
avoided wherever possible. Where it is impossible to
avoid installing a lift in an adverse atmosphere, the
PART 8 BUILDING SERVICES — SECTION 5 INSTALLATION OF LIFTS AND ESCALATORS
25
electrical equipment should be of suitable design and
construction to meet the conditions involved.
6.4.3.1 Normally goods lifts have lower speeds than
passenger lifts for the same travel because traffic
conditions are less demanding, and more time is
required for loading and unloading.
6.4.3.2 As loads for goods lifts increase in size and
weight, so the operation of loading and unloading
becomes more difficult. Therefore, it is usual to require
greater accuracy of levelling as the capacity of the
goods lift increases.
6.4.3.3 A large capacity goods lift at high speed is
often a very uneconomical preposition. The inherent
high cost is enhanced due to the very small demand
for such equipment, much of which is custom made.
The high capital cost of the lift, building work and
electrical supply equipment usually shows a much
smaller return as an investment than more normal sizes
of lifts.
6.4.4 Hospital Bed Lifts
Hospital bed lifts should be situated conveniently near
the ward and operating theatre entrances. There shall
be sufficient space near the landing door for easy
movement of stretcher.
It is convenient to place the passenger lifts in a hospital,
near the staircases.
6.5 Structural Considerations
6.5.1 Lift well enclosures, lift pits, machine rooms and
machine supports besides conforming to the essential
requirements given in 4, should form part of the
building construction and comply with the lift
manufacturer's drawings.
6.5.2 Machine Room
Floors shall be designed to carry a load of not less
than 350 kg/m 2 over the whole area and also any load
which may be imposed there on by the equipment used
in the machine room or by any reaction from any such
equipment both during periods of normal operation
and repair.
6.5.3 The side wall of the lift well may be made of
reinforced cement concrete at least 150 mm thick so
as to provide satisfactory anchoring arrangement for
fixing. Reference shall also be made to Part 6 'Structural
Design, Section 5 Plain, Reinforced and Prestressed
Concrete, 5A Plain and Reinforced Concrete'.
6.5.4 The total load on overhead beams shall be
assumed as equal to all equipment resting on the beams
plus twice the maximum load suspended from the
beams.
6.5.5 The factor of safety for all overhead beams and
supports based on ultimate strength of the material and
load in accordance with 6.5.4 shall be not less than the
following:
For Steel 5
For Reinforced Concrete 7
The deflection of the overhead beams under the
maximum static load calculated in accordance with
above shall not exceed 1/1 500 of the span.
6.6 Access to Machine Room and Lift Pits
6.6.1 Access to machine room above a lift well may
be either from the roof or by an internal staircase with
a proper arrangement for fixing.
6.6.2 Access between a secondary floor and a machine
room may be by ladder. Where a machine room
entrance is less than 1.5 m above or below the adjacent
floor or roof surfaces, a substantial permanently
attached ladder may be used. Ladders shall be fixed at
least 150 mm clear of any wall, beam or obstruction
and shall extend at least to the landing level. Above
the landing level and for a height of at least 1.15 m,
either the ladder stringers shall be extended or suitable
hand grips shall be provided.
6.6.3 Where the machine room entrance is 1.5 m or
more above or below the adjacent floor or roof surface,
access shall be provided by means of stairs in accordance
with the requirements given in 6.6.3.1 to 6.6.3.6.
6.6.3.1 The angle of inclination of the stair shall not
exceed 50° from the horizontal and the clear width of
the stair shall be not less than 600 mm.
6.6.3.2 The tread shall have a non-slip surface which
shall be not less than 150 mm wide for open stair
construction and not less than 20 cm wide for closed
stair construction.
6.6.3.3 The rise of the stair shall not exceed 250 mm.
6.6.3.4 A hand rail shall be provided on the outer
stringer of all stairways fixed at a convenient height,
but not less than 500 mm high measured vertically from
the nosings, and not less than 1 m high on landings
and platforms. Such hand rail shall have atleast 50 mm
clearance between nearest permanent object at the
corresponding side of the stair.
6.6.3.5 Headroom clearance of not less than 2 m
measured from the nosings of the stairway, shall be
provided on every stairway.
6.6.3.6 Heights of stairs over 5 m in length shall be
provided with intermediate landings.
NOTE — Where compliance with any of the requirements
specified in 6.61 to 6.6.3 is impracticable, applications for
variation shall be made to the Authority, who may, vary such
requirements.
26
NATIONAL BUILDING CODE OF INDIA
6.6.4 Access to a machine room in a basement may
be provided from a corridor.
6.6.5 Access to a machine room via the lift well shall
be prohibited.
6.6.6 The lift pit should be capable of being examined
by a separate access. In the case of a battery of two
lifts, it is possible to examine the lift pit through the
adjoining one.
6.7 Fire Protection
To prevent fire from spreading by means of the lift
well, lift well enclosures shall conform to the
requirements given in Part 4 'Fire and Life Safety'.
The machine room should be constructed of a suitable
grade of fire-resisting material and precautions should
be taken to minimize spread of fire from the machine
room into the lift well (see also 7.3.14).
6.8 Requirements for Fireman's Lift
6.8.1 For buildings having height of 15 m or more
atleast one lift shall meet the requirements of fireman' s
lift as given in 6.8.2.
6.8.2 The fireman's lift shall have the following
minimum requirements:
a) Lift car shall have floor area of not less than
1.44 square meters. It shall also have a
loading capacity of not less than 544 kg
(8 persons).
b) Lift landing doors shall have a minimum of
fire resistance of one hour.
c) Doors shall be of automatic operation for car
and landing.
6.8.3 Fireman's lifts in a building having more than
1 5 m or more height, shall work at or above the speed
of LO m/s so as to reach the top floor from ground
level within one minute.
6.8.4 Operation Requirements of Fireman 's Lift
The lift shall be provided with the following as a
minimum:
a) A two position switch at evacuation floor
(normally main entrance floor) (ON/OFF),
and
b) Buzzer and 'Fireman's lift' — light in car
6.8.4.1 Sequence of operation:
a) Return to evacuation floor (Phase 1):
1) Shall start when the switch at the
evacuation floor is turned to the "ON"
position or the signal from smoke
detector (if provided by the Building
Management System) is on. All lift(s)
controlled by this switch shall cancel all
existing car calls and separate from
landing calls and no landing or car calls
shall be registered. The buzzer and
"fireman's lift" light shall be turned on.
All heat and smoke sensitive door re-
opening devices shall be rendered
inoperative.
2) If the lift is travelling towards the
evacuation floor, it shall continue driving
to that floor.
3) If the lift is travelling away from the
evacuation floor, it shall reverse its
direction at the nearest possible floor
without opening its doors and return non-
stop to the evacuation floor.
4) If the lift is standing at a floor other than
the evacuation floor, it shall close the
doors and start travelling non-stop to the
evacuation floor.
5) When at the evacuation floor the lift shall
park with doors open.
6) The buzzer is turned off after this return
drive.
b) Fireman's service (Phase 2):
The phase 2 operation of the lift shall be as
defined below.
1) The phase 2 is started after phase 1, if
the switch is "ON".
2) The lift does not respond to landing calls
but registers car calls. All heat and smoke
sensitive door reopening devices are
rendered inoperative.
3) When the car call button is pressed the
doors start closing. If the button is
released before the doors are fully closed,
they re-open. The car call is registered
only when the doors are fully closed.
4) After registering a car call the lift starts
driving to the call. If more than one car
call is registered, only the nearest call is
answered and the remaining calls will be
cancelled at tha first stop.
5) At the floor the doors are opened by
pushing the door open button. If the
button is released before the doors are
fully open, they re-close.
6) The lift returns to normal service when it
stands at the evacuation floor with doors
open and the switch is "OFF'.
6.9 Supply Cables and Switches
Each lift should be provided with a main switch or
circuit breaker of a capacity determined by the lift
PART 8 BUILDING SERVICES — SECTION 5 INSTALLATION OF LIFTS AND ESCALATORS
27
manufacturer and the incoming supply cable should
terminate in this switch. For a single lift, this switch
should be fixed adjacent to the machine room entrance
inside the machine room. In a machine room common
to more than one lift, each main switch should be
conveniently situated with respect to the lift it controls.
Switches and fuses (which may form part of a
distribution switch-board) should be provided for
isolating the supply cables to the machine room.
6.10 The detailed design considerations for different
types and selection of the lifts shall be done in
accordance with good practice [8-5(5)].
7 POWER AND CONTROL SYSTEMS
7.1 Features Associated with Power Systems
7.1.1 Industrial Switchgear
Switchgear for controlling lift power systems is
characterized by its high duty cycle and its high
rupturing capacity. Switchgear must be robust enough
and shall be so designed as to withstand the high duty
cycle and high rupturing capacity introduced during
the operation of the lifts.
7.1.2 Levelling Accuracy
The levelling tolerances in accordance with good
practice [8-5(4)] are those which can be reasonably
expected between no load and full load in either
direction.
Where greater levelling accuracy is required, careful
examination should be made to see whether such
increased precision is justified or practical. Advice
should also be obtained, as additional apparatus and
cost may be involved, and in some cases the
requirement may not be practicable.
7.1.3 Corrective Levelling
This should only be used when it is impossible
otherwise to achieve the required levelling tolerances
or on long travel lifts to maintain the required levelling
tolerances during loading and unloading.
7.1.4 Levelling with Variable Voltage
A variable voltage system is one using continuous
regulation which minimizes speed differences due to
load variation. Therefore, the actual levelling speed is
of less importance than the general refinement of its
regulation control. In fact no levelling speed as such
may be identifiable.
7.1.5 Overload Tests
A lift is designed to operate and transport the contract
load at the required duty cycle, and should not by
intention or habitually be used to carry overloads.
During test as a safeguard to cover variable supply
and temperature conditions a lift is checked for the car
to complete one round trip with contract load plus 10
percent at nominal supply voltage and nominal ambient
temperature. There is also a static test with contract
load plus 25 percent to check that the brake will sustain
the car.
It is unnecessary to specify and additional overload
test or capacity and in fact it is detrimental to the normal
running efficiency and safety of the lift to do so.
7.1.6 Occasional Extra Load
It is not good practice to request that a lift should be
designed to carry an occasional extra load. It is
tantamount to specifying an excessive overload test
which is detrimental to the normal running efficiency
and safety of the lift.
7.2 Description of Operation Systems
7.2.1 Methods of Control Systems
The methods of control systems are as follows:
a) Attendant and dual control (see 7.2.2), and
b) Automatic push button operation (see 7.2.2).
7.2.1.1 Types of control systems
a) Collective control (see 7.2.3),
b) Single push button collective control (see
7.2.4),
c) Down collective control (see 7.2.5),
d) Directional collective control for one car (see
7.2.6),
e) Directional collective control for two or three
cars (see 7.2.7), and
f) Group supervisory control (see 7.2.8).
Features of control systems are described in 7.3.
7.2.2 Automatic Push Button Operation
Automatic control is a method of operation by which
a momentary pressure on a push button sets the car in
motion and causes it to stop automatically at any
required lift landing. This is the simplest control system
and it is sometimes referred to as push button control.
A car answers a landing or car call whichever is
actuated first by momentary pressure provided the lift
is not in use. Momentary pressure of a car push button
will send the car to the designated floor. The car always
responds to a car push button in preference to a landing
push button.
With this type of control, a RED landing signal light
or direction arrow indicates that the car is in use that is
the lift is travelling.
This type of control is recommended for the following
applications.
28
NATIONAL BUILDING CODE OF INDIA
a) A single passenger lift serving up to 4 floors.
b) Goods lifts serving any number of floors
where it is usually the most suitable form of
control.
For special purposes, the following two systems may
be considered:
a) Despatch from landings as an additional
feature for a goods lift with manually operated
doors. The call is registered by pressing the
car push button and when the doors are closed
the car will travel to the designated floor.
b) Automatic with attendant control as an
additional feature on goods lifts with a key
operated switch in the car to transfer the
control from normal automatic to attendant
operation. There is also a visual call indicator
with buzzer in the car to indicate to the
attendant the landing floors at which push
buttons have been pressed when the car is
under attendant control.
7.2.3 Collective Control
Collective control is a generic term for those methods
of automatic operation by which calls made by pressing
push buttons in the car and at lift landings are registered
and answered by the car stopping in floor sequence at
each lift landing for which calls have been registered
irrespective of the order in which the calls have been
made, and until all calls have had attention.
Collective control of any form is usually not suitable
for goods lifts except where loading is not expected to
fill the car and additional loads can be taken at other
stops.
7.2.4 Single Push Button Collective Control
Single push button collective control has a single push
button at each landing. It is not recommended, as the
direction in which it is desired to travel cannot be
registered by the intending passenger.
7.2.5 Down Collective Control
Down collective is a control system where landing calls
are registered from a single push button, irrespective
of the car being in motion or the landing door being
open and calls are stored until answered. Any number
of car calls can be registered and the car will stop in
sequence in the down direction at each of the
designated floors. The car will travel in the up direction
to the highest call registered stopping only in response
to car calls. It will then travel downwards answering
calls in floor sequence. If only one call has been
registered the car travels to the floor of call.
This system is suitable where there is traffic between
the ground and upper floors only and no interfloor
traffic. Two or three car banks have interconnected
control.
With this type of control the following signals are
included:
a) A landing signal light indicates that the call
has been registered and will be answered.
b) Illuminated car position indicator above car
entrance.
7.2.6 Directional Collective Control for One Car
Directional collective control for one car is a control
system having UP and DOWN push buttons at
intermediate landings whereby the call is registered
for the intended direction of travel. Calls from the car
or landing push buttons are registered and stored until
answered. The car will answer calls in floor sequence
in one direction of travel. Calls for the opposite
direction of travel are answered when the direction of
travel is reversed.
This system is suitable for single lifts serving 4 or more
floors with interfloor traffic, such as small office
blocks, hotels and blocks of flats.
With this type of control the following signals are
included:
a) A landing signal light for each landing push
button indicates that the call has been
registered and will be answered.
b) Illuminated car position indicator above the
entrance in the car.
c) Arrow shaped signal lights in the back of the
car or on the landing to indicate to the entering
person in which direction the car is going to
depart.
7.2.7 Directional Collective Control for Two or Three
Cars
Directional collective control for two or three cars is a
system covering a control in which the two or three
cars in a bank are interconnected. One push button unit
with UP and DOWN push buttons or floor buttons (in
case of car control from floor) are required at each
landing and the call system is common to all lifts. If
for architectural balance, in the case of a three car bank,
extra push button units are required, these should be
specified. Each landing call is automatically allocated
to the best placed car. The control is designed so that
cars are effectively spaced and thus give even service.
When a car reaches the highest floor to which there is
a call its direction of travel is automatically reversed
when it next starts. One or more cars will return to the
parking floor.
Automatically bypassing of landing calls when a car
is fully loaded is an essential feature for three-car
PART 8 BUILDING SERVICES — SECTION 5 INSTALLATION OF LIFTS AND ESCALATORS
29
banks. It is also necessary for two-car banks in offices.
Other cars will continue to provide service to all floors.
When three-car banks serve 7 or 8 floors and over,
some form of automatic supervisory control {see 7.2.8)
is generally necessary in the interest of efficiency.
With this type of control the following signals are
included:
a) A landing signal light for each landing push
button to indicate that the call has been
registered and will be answered.
b) Illuminated car position indicator above the
entrance in the car.
c) Arrow shaped signal lights in conjunction
with an audible single stroke gong or an
indication on the landing call push button
station above each landing entrance to
indicate to the waiting person(s) which car is
going to stop and in which direction it will
continue its course.
7.2.8 Group Supervisory Control
A bank or group of intensive traffic passengers lifts
requires a supervisory system to co-ordinate the
operation of individual lifts which are all on collective
control and are interconnected.
The very nature of intensive service calls for a
sophisticated automatic supervisory control system so
as to match the speed capacity of these lifts.
The supervisory system regulates the despatching of
individual cars and provides service to all floors as
different traffic conditions arise minimizing such
unproductive factors as idle cars, uneven service and
excessive waiting time. The system will respond
automatically to traffic conditions such as UP and
DOWN peaks, balanced or light traffic and provides
for other specialized features.
If desired, a master station can be provided in the lift
lobby which gives by indicators, visual information
regarding the pattern under which the system is
operating. Where the system is based on a definite
programme, control means are provided for altering
the type of traffic programme. There are other facilities,
such as the removal of any lift from service.
7.3 Features of Operation Systems
7.3.1 Car Preference
Sometimes it is necessary to give a special personal
service or a house service. When this service is required
and for whatever purpose, it should be specified as
'car preference' is by a key operated switch in the car.
The operation is then from the car only and the doors
remain open until a car call is registered for a floor
destination. All landing calls are bypassed and car
position indicators on the landing for this lift are not
illuminated. The removal of the key when the special
operation is completed restores the control to normal
service.
7.3.2 Landing Call Automatic Bypass
For collective operation, automatic bypassing of
landing calls can be provided. This device will bypass
landing calls when a car is fully loaded but the calls
are not cancelled.
7.3.3 Motor Generator Shut Down
Lifts controlled by variable voltage system automatically
shutdown when subject to an over-riding control which
puts them out of service under certain conditions; for
example, no demand for lift service. They are
automatically put back into service as required.
7.3.4 Basement Service
For lifts with collective control when service is required
below the main parking floor, which is usually the
ground floor, to a basement and/or a sub-basement,
the lift maker should be informed of the type of service
required, as special technical considerations are then
usually necessary.
7.3.5 Hospital Service
Lifts for carrying beds and stretchers require a car
preference switch so than an attendant can have
complete control of the car when required. This
requirement should be specified as 'car preference' and
it will function as described in 7.3.1. Otherwise such
lifts can have the same control systems as for normal
passenger lifts, the choice depending on the number
of floors served, the service required and the number
of lifts.
7.3.6 Manually Operated Doors (Without Closers)
A 'door open' alarm should be provided to draw
attention to a car or landing door which has been left
open.
7.3.7 Automatically Power Closed Doors
For passenger operation when the car arrives at a
landing the doors will automatically open and then
close after lapse of a time interval. This time interval
can be overruled by the pressure of a push button in
the car to give instant door closing.
An 'open door' push button is provided in the car to
reverse closing motion of the doors or hold them open.
7.3.8 Controlled Power Closed Doors
When there are conditions that particularly affect the
safety of passengers or damage to vehicles or trucks,
the closing of the doors should only be made by the
30
NATIONAL BUILDING CODE OF INDIA
continuous pressure of push buttons in the car or on
landings.
A 'door open' alarm should be provided to draw
attention to a car or landing door which has been left
open. This means of operation is required for some
forms of goods lifts.
7.3.9 Safe Operation of Doors
The safety of passengers passing through lift entrances
is fully covered by the provision of good practice
[8-5(9)]. No modification of these provisions should
be specified.
7.3.10 Director Service
There are many forms of giving special service for
individuals, but they should always be avoided. They
range from key operated switches at preferred landings
to the complete segregation of one out of a bank of
lifts. It is obvious that any preferential treatment of
this nature can seriously jeopardize the efficiency of
the service as a whole. When a bank of say three lifts
is installed to meet the anticipated traffic requirements
and then, when the building is occupies, one lift is
detached permanently for directors' service, the traffic
handling can be reduced by a half rather than a third.
When preferential service is imperative, then the car
preference feature should be available {see 7.3.1).
7.3.11 Indication of Car Arrival
As all lift cars are illuminated when available (in
service). It is recommended that this illumination be
used to signal the arrival of a car at a landing in
preference to special signals such as LIFT HERE signs
since signal lamps can fail when the lift is still operating
satisfactorily.
The following is the practice adopted for vision panels
in doors:
a) For lifts with manually operated car and
landing doors, vision panels are provided in
all doors;
b) For lifts with power operated car doors and
manually operated landing doors, vision
panels are provided in the landing doors only;
c) For lifts with automatically opened car and
landing doors, no vision panels are required;
and
d) When vision panels are provided they should
comply with the requirements of good
practice [8-5(4)].
7.3.12 Service Switches
When switches are provided to take cars out of service,
that is because the remaining cars in the group can
cater for the required passenger traffic, it is essential
that such switches should not stop the fireman's control
from being operative in the event of the lift being
designated as a fireman's lift. Service switches should
not be confused with maintenance switches which are
only used when it is dangerous to attempt to operate
the lift because maintenance work is actually in
progress. A control station fitted on top of the car is
regarded as a maintenance switch.
7.3.13 Fire Switch
When required by the fire authority a fire switch has
to be provided, the function of which is to enable the
fire authority to take over the complete control of one
or more lifts in an installation [see good practice
[8-5(4)]}.
7.3.14 Push Buttons and Signals
It is most important that the purpose of every push
button and signal should be clearly understood by all
passengers.
7.3.15 In public places where blind persons are
expected to use the lifts it is recommended to provide
Brailey buttons.
7.4 Electrical Installation Requirements
7.4.1 General
The good practices [8-5(4)] states the requirements for
main switches and wiring with reference to relevant
regulations. The lift maker should specify, on a
schedule, particulars of full load current, starting
current, maximum permissible voltage drop, size of
switches and other details to suit requirements. For
multiple lifts a diversity factor may be used to
determine the cable size and should be stated by the
lift manufacturer.
It is important that the switches at the intake and in the
machine room which are provided by the electrical
contractor are the correct; size, so that correctly rated
HRC fuses can be fitted. No form of 'NO VOLT' trip
relay should be included anywhere in the power supply
of the lift.
a) Power supply mains — The lift sub-circuit
from the intake room should be separate from
other building service.
Each lift should be capable of being isolated
from the mains supply. This means of
isolation should be lockable.
b) For banks of interconnected lifts, a separate
sub-circuit is required for the common
supervisory system, in order that any car
may be shut down without isolating the
supervisory control of the remainder.
PART 8 BUILDING SERVICES — SECTIONS INSTALLATION OF LIFTS AND ESCALATORS
31
c) Lighting — Machine rooms and all other
rooms containing lift equipment should be
provided with adequate illumination and with
a switch fixed adjacent to the entrance. At
least one socket outlet, suitable for lamps or
tools, should be provided in each room.
The supply to the car light should be from a separate
circuit, and controlled by a switch in the machine room.
For multiple lifts with a common machine room a
separate supply should be provided for each car. The
car lighting supply should be independent of the power
supply mains. Plug should be provided with a light,
the switch for which should be in the lift well, and
accessible from the lower terminal floor entrance.
When the alarm system is connected to a transformer
or trickle charger, the supply should be taken from the
machine room lighting.
7.4.2 Electric Wiring and Apparatus
7.4.2.1 All electrical supply lines and apparatus in
connection with the lift installation shall be so
constructed and shall be so installed, protected, worked
and maintained that there may be no danger to persons
therefrom.
7.4.2.2 All metal casings or metallic coverings
containing or protecting any electric supply lines of
apparatus shall be efficiently earthed.
7.4.2.3 No bare conductor shall be used in any lift car
as may cause danger to persons,
7.4.2.4 All cables and other wiring in connection with
the lift installation shall be of suitable grade for the
voltage at which these are intended to be worked and
if metallic covering is used it shall be efficiently
earthed.
7.4.2.5 Suitable caution notice shall be affixed near
every motor or other apparatus in which energy is used
at a pressure exceeding 250 V.
7.4.2.6 Circuits which supply current to the motor shall
not be included in any twin or multicore trailing cable
used in connection with the control and safety devices.
7.4.2.7 A single trailing cable for lighting control and
signal circuit shall be permitted, if all the conductors
of this trailing cable are insulated for maximum voltage
running through any one conductor of this cable.
7.4.3 Emergency Signal or Telephone
It is recommendatory that lift car be provided either
with an emergency signal that is operative from the
lift car and audible outside the lift well or with a
telephone.
When an alarm bell is to be provided each car is fitted
with an alarm push which is wired to a terminal box in
the lift well at the ground floor by the lift maker. This
alarm bell, to be supplied by the lift maker (with
indicator for more than one lift) Should be fixed in an
agreed position and wired to the lift well. The supply
may be from a battery (or transformer) fixed in the
machine room or, when available, from the building
fire alarm supply.
When a telephone is to be provided in the lift car the
lift maker should fit the cabinet in the car and provided
wiring from the car to a terminal box adjacent to the
lift well.
The type of telephone should be stated in the enquiry.
7.4.4 Earthing
7 AAA The terminal for the earthing of the frame of
the motor, the winding machine, the frame of the
control panel, the cases and covers of the tappet switch
and similar electric appliances which normally carry
the main current shall be at least equivalent to a 5 mm
diameter bolt, stud or screw. The cross-sectional area
of copper earthing conductor shall be not smaller than
half that of the largest current-carrying conductor
subject to an upper limit of 65 mm 2 [see also good
practice [8-5(10)]}.
7.4.4.2 The terminal for the earthing of the metallic
cases and covers of door interlocks, door contacts, call
and control buttons, stop buttons, car switches, limit
switches, junction boxes and similar electrical fittings
which normally carry only the control current (such
terminal being one specially provided for this purpose),
and the earth conductor should be appropriately sized
in accordance with good practice [8-5(10)].
The size of earthing conductor shall be in accordance
with Part 8 'Building Services, Section 2 Electrical and
Allied Installations'.
7.4.4.3 The earthing conductor shall be secured
to earthing terminal in accordance with the
recommendations made in good practice [8-5(10)] and
also in conformity with the latest provisions of
Electricity Act, 2003 and Rules framed thereunder from
time to time.
7.4.4.4 The exposed metal parts of electrical apparatus
installed on a lift car shall be sufficiently bonded and
eartherd.
7.4.4.5 Where screwed conduit screws into electric
fittings carrying control current making the case and
cover electrically continuous with the conduit, the
earthing of the conduit may be considered to earth the
fitting. Where flexible conduit is used for leading into
a fitting, the fitting and such length of flexible conduit
shall be effectively earthed.
32
NATIONAL BUILDING CODE OF INDIA
7.4.4.6 One side of the secondary winding of bell
transformers and their cases shall be earthed.
7.4.4.7 Where there are more than one lift in a
building, there should be a separate earth pit for the
lifts.
7.5 Building Management Systems — Interface for
Lifts
7.5.1 Where more than three lifts are provided in a
building and especially when these are provided at
different locations in the building a form of central
monitoring may be provided. Such central monitoring
may be through a Building Management Systems, if
provided in the building or through a display panel.
7.5.2 The following signals should be given to the
building management interface from each lift.
a) Alarm button in car,
b) Door Zone or floor level information,
c) Lift moving information,
d) Power on information, and
e) Lift position information.
7.5.3 Each of these signals shall be provided through
a potential free contact located in the lift machine
room. The contacts shall be rated for 230 V ac/lA or
24 V dc/1 A. A pair of wires should be used for each
potential contact.
7.5.4 The wiring between lift machine room to
Building Management Systems shall be planned and
carried out by the builder along with other wiring in
the building.
7.5.5 The building management system should ensure
that any position information is read only when the
lift is not moving (lift moving information) or is
capable of reading several times to detect a stable state.
In addition to the signals above the following signals
may be added if required for the benefit of monitoring
the lift performance.
a) A summary fault output to indicate a lift in
fault condition, which prevents the lift from
providing service. This summary fault
condition shall include the most common
faults such as safety circuit open.
b) Service or inspection mode.
c) Attendant mode.
d) Fire mode.
e) Doors opening.
f) Doors closing.
g) Lift moving up.
(In combination with lift moving and lift
moving up information, lift moving down
information can be sensed by the Building
Management Systems),
h) Door Reopen Request (Summary of Door
Open, Light Curtain, Photocell, Safety Edge
Signals).
7.5.6 Where it is desired that it should be possible to
control the lift from Building Management Systems,
the following control signals can be provided.
a) Normal to service/inspection mode change
over (
b) Fault Accept/Rest Input
(Using this input, the lift controller may be
allowed to clear an existing fault if this is
other wise safe. It will be decided by the Lift
manufacturer as to what faults can be
cleared)
c) Car call to top most floor and bottom most
floor of each lift.
Where such control inputs are provided, it should be
with a pass word and login feature that allows one to
determine who has used these inputs and at what time.
Always such inputs should be through authorized
person only. The Building Management Systems
should make all changeovers effective only when lift
is not moving.
7.5.7 Control inputs from Building Management
Systems should be through a potential free contact
capable of carrying 24 V dc/1 A or 230 V ac/1 A. The
wiring should be terminated in each lift machine room.
8 CONDITIONS FOR OPTIMUM PRACTICE
8.1 Lift Entrance Operation
8.1.1 General
Every lift journey involves two horizontal movements,
in and out of the car, to one vertical movement. The
type of door, and the operation of the doors, play a
main part in the service given, and should receive
careful consideration.
8.1.2 Goods Traffic
Most types of goods traffic require relatively longer
loading and unloading times and manual doors are
frequently used for economy and simplicity.
Power operation can be applied, especially for large
entrances, to give automatic opening: the doors then
always open fully, reducing the risk of damage. For
many types of goods traffic, it is preferable for closing
though powered, to be controlled by continuous
pressure button, rather than being automatically
initiated {see good practice [8-5(4)] }.
For heavy duty lifts, a power operated vertically sliding
PART 8 BUILDING SERVICES — SECTION 5 INSTALLATION OF LIFTS AND ESCALATORS
33
door preferred, this can be made extremely robust, and
is capable of extension to very large entrances.
8.2 Painting at Works and on Site
Lift equipment with normally receive a protective coat
of paint at works before despatch to site. Further
painting of lift equipment may be necessary and is
normally in the form of a finishing coat and can take
place on site. Alternatively, the further painting of the
equipment may be carried out at works as a finishing
coat with normal touching up after site erection as may
be necessary.
Any additional painting, due to site conditions during
erection and/or final operating conditions in the
premises, is subject to negotiation between the lift
maker and the purchaser.
Decorative finishes are a subject for separate
negotiation.
8.3 Special Environments
Standard equipment is suitable for use inside normal
residential, commercial and industrial buildings
but when unusual environments are likely to be
encountered, the advice of the lift maker should be
sought at the earliest possible stage to enable the most
economic satisfactory solution to be found. Special
mechanical protection and or electrical enclosures may
be necessary as well as compliance with statutory or
other regulations and with the purchaser's particular
requirements, which should be fully considered at the
time of enquiry.
Examples of situations which necessitate special
consideration are;
a) Exposure to weather, for example, carparks.
b) Low temperatures, for example, cold stores.
c) High temperatures, for example, boiler plant.
d) Hosing-down for example, for hygiene or
decontamination.
e) Corrosive atmosphere, for example, chemical
works.
f) Dusty atmospheres, for example, gas plant.
g) Explosive and inflammable atmosphere, for
example gas plants, and petroleum and
polyester industries.
8.4 Ventilation of Machine Rooms
Machine rooms shall be ventilated. They shall be such
that the motors and equipment as well as electric cables
etc, are protected as far as possible from dust, harmful
dusts and humidity. The ambient temperature in the
machine room shall be maintained between 5°C and
40°C.
8.5 Lighting and Treatment of Walls, Floors, Etc
8.5.1 All machine rooms should be considered as plant
space, and conditions provided to permit reliable
operation of electrical switchgear and rotating
machinery, and be conducive to good maintenance.
Lighting should be provided to give at least 200 lux
around the controller and machine. The machine room
walls, ceiling and floor should be faced in dust-resisting
materials, tiles, etc, or painted as a minimum to stop
dust circulation which otherwise could damage rotating
machinery and cause failure of switchgear. Machine
rooms should also be weatherproof and if ventilation
louvers are provided they should be designed and sited
to prevent snow being driven through or to the
apparatus.
8.5.2 Lift wells should be constructed to be
weatherproof and of a dust free surface material or
should be painted to minimize dust circulation on to
moving apparatus and from being pumped by the car
movement into machine rooms or on to landings.
Sufficient number of light points should be provided
in the lift shaft for proper illumination.
8.5.3 Should a lift entrance open out into an area
expected to the weather the entrance should be
protected by a suitable canopy and the ground level
slope up to the entrance to prevent during rain or
surface drainage from entering the lift well through
the clearances around the landing doors. Any push
buttons so enclosed should be of weatherproof type.
8.6 Stairwell Enclosures
The location of lifts in stairwells is not recommended.
The use of stair stringers for fixing of guides normally
involves extensive site measurement in order to
fabricate purpose-made brackets. The resulting
attachments are often unreliable and lacking in
robustness. For stairwells of normal width, the span
required for the lift machine support beams is
excessive and unless uneconomic sections are used the
deflections under varying load adversely affect the
motor of the lift.
The necessary provision of suitable continuous
enclosures can be very expensive.
8.7 Handwinding Release Procedure and Indication
The release procedure by handwinding should only
be carried out in an emergency and by authorized
persons who have received the necessary instruction
because it is dangerous for any other persons to attempt
to do so.
Before attempting to move the car, it is imperative that
any person in the car be warned of the intention to
34
NATIONAL BUILDING CODE OF INDIA
move the car and that they do not attempt to leave the
car until they are advised that it is safe to do so. Any
failure to carry out this precaution may render the
person concerned guilty of negligence should an
accident occur.
Before attempting to handwind the lift machine, it is
vital that the supply is switched off at the main switch.
It is usually necessary to have two persons in the
machine room: one to operate the brake release and
the other to carry out the handwinding. The
exceptions are small lift machines where the
handwinding and be easily controlled by one man and
larger machines which need two men to operate the
handwinding alone with an additional man to control
the brake release.
If the car is stuck in the lift well and cannot be moved
when an attempt is made to move it in a downward
direction, then no attempt at handwinding should be
made because the car safety gear may have set. Any
further procedure should be carried out under the
instruction of a qualified lift mechanic.
Provided the car is free to be moved in the downward
direction, then it should be hand wound to the nearest
floor. There is a preference to move the car in a
downward direction. However, this may not always
be practical owing to the distance involved and the
time taken to complete the movement. In addition the
amount of out of balance load on the counterweight
side, due to the size of car and the small number of
persons inside it, may make it necessary to wind the
car upwards. In the case of higher speed lifts the
direction of handwinding will usually be governed by
the effort required to move the car because of the
absence of a large gear reduction ratio.
It is essential that all detail operations be carried out
according to the manufacturer's instructions for the
lift concerned and these should be clearly stated and
permanently displayed in the form of a notice in the
machine room.
9 RUNNING AND MAINTENANCE
9.1 The lift installation should receive regular
cleaning, lubrication, adjustment and adequate
servicing by authorized competent persons at such
intervals as the type of equipment and frequency of
service demand. In order that the lift installation is
maintained at all times in a safe condition, a proper
maintenance schedule shall be drawn up in consultation
with the lift manufacturer and rigidly followed. The
provision of a log book to record all items relating to
general servicing and inspection is recommended for
all lifts. It is essential that the electrical circuit diagram
of the lift with the sequence of operation of different
components and parts should be kept readily available
for the persons responsible for the maintenance and
replacement where necessary.
9.2 Particular attention may be directed for thorough
periodical examination of wire ropes when in service.
Attention should also be directed to the thorough
examination of the groove of drums, sheaves and
pulleys when installing a new rope. A groove deepened
by rope wear is liable to lead to early failure of a new
rope unless the groove is returned.
9.3 Any accident arising out of operation of maintenance
of the lifts should be duly reported to the Authority in
accordance with the rules laid down. A notice may be
put in the machine room to this effect.
10 LIFT ENQUIRY OR INVITATION TO TENDER
10.1 General
A period of four weeks is normally sufficient for return
of tenders. This should be extended if large numbers
of lifts or special requirements are involved.
The enquiry documents should be kept to the essential
minimum, and should be strictly confined to material
relevant to the lift work and to the particular project
concerned
When enquiring for and ordering an electrical lift in
accordance with this Section, the particulars given
below shall be furnished:
PARTICULARS OF LIFTS
1) Type of lift (Passenger, goods, service or
dumb waiter) ,
2) Number of lifts required
3) Load: number of persons kg
4) Rated speed m/s
5) Travel m
6) Serving floors entrances
7) Number of floors served
8) Method of control.... (see 7,2)
9) Position of machine room
10) Sizes of lift well(s)
1 1 ) Position of counterweight.
1 2) Internal size of lift car
13) Construction, design and finish of car
bodywork
14) Car entrances:
a) Number, size and type of doors
b) Power or manual operation
15) Car light
16) Call indicator position indicator
in car
PART 8 BUILDING SERVICES — SECTION 5 INSTALLATION OF LIFTS AND ESCALATORS
35
17) Lift Landing Entrance:
a) Number, size and type of doors or gates
or shutters (for goods lifts)
b) Location of landing entrances in different
floors, if the car has more than one
opening.
18) Electric Supply:
Power volts ac/dc
phase
Cycles , wire system
19) Whether neutral wire available for control
circuit?
20) Lighting volts ac/dc
cycles
21) Are premises subject to Lifts Act/Rules?
22) Proposed date for commencement on
site
23) Proposed date for completion
24) Additional items, if required
25) Booklet giving complete details of maintenance
schedule and circuit diagram where so
specified
10.2 Additional Items
The enquiry should state any additional items required
beyond those specified in good practice [8-5(4)], such
as fireman's control, radio interference suppression and
dismantling of existing lift, etc.
Lifts to be installed in adverse conditions, such as
chemical works, lifts used with power trucks, and
similar specialized applications, required individual
consideration according to the circumstances.
10.3 Finishes
Finishes should be specified at the enquiry stage or
provisional sums should be included for them.
Finishes to be considered may include car body work,
ceiling, floor, light fitting, ventilation, trims, car and
landing doors, including vision panels if required,
landing architrave push and indicator fittings, car and
landings.
10.4 Inclusions and Exclusions
A number of peripheral items are associated with a lift
installation, of which some should always be provided
by the builder, and some are best included by the lift
maker. The requirements vary to some extent with the
type of installation.
It is important that the limits of responsibility are
clearly understood, and the enquiry documents should
be specific in this respect.
The lift maker should include such items as:
a) Guide brackets and wall inserts;
b) Buffers and any associated steelworks;
c) Pit screen to counterweight;
d) Steel beams of raft for machine and pulleys;
e) Sound insulation to machine where this is
required;
f) Doors;
g) Door tracks;
h) Supporting steelworks for horizontal sliding
doors and frames for hinged doors;
j) Wiring materials for the lift itself starting from
the supplies furnished by the purchaser;
k) Over current protection (type to be specified)
(see 7.4.1);
m) Alarm push and bell or telephone (see 7.4.3);
n) Alarm push and bell or telephone (see 7.4.3);
p) Lifting tackle and small electric tools for use
during the actual installation;
q) Services of erection staff to install and wire;
r) Services of testing engineer and provision of
the necessary instruments and test weights; and
s) Guarantee of equipment.
The lift maker should exclude the supply and fixing of
the items as the following:
a) Builders' work, such as forming lift well, pit
and machine room and building in wall
inserts;
b) Machine room floor including any
reinforcement necessary for load bearing;
c) Lifting beams in machine room where
necessary;
d) Steel surrounds for vertical bi-parting sliding
doors;
e) Any necessary tanking, lining or reinforcement
of the pit;
f) Dividing beams for multiple wells, and
interwell pit screens;
g) Temporary guarding of openings;
h) Scaffolding, planks and ladders;
j) Off-loading and storage of materials;
k) Cutting away and making good;
m) Site painting of steel work, etc;
n) Working lights, temporary and permanent
electricity supplies, etc; and
p) Mess rooms, sanitary accommodation and
welfare facilities.
For more detailed discussion of the requirements for
site preparation and work by other trades, reference
36
NATIONAL BUILDING CODE OF INDIA
should be made to good practice [8-5(2)], and to other
clauses 5, 7.4 and 12.
Apart from the items referred to in the preceding
clauses, which are common to almost all lift installations,
the following shall apply:
a) Sill support members with toe guards are
included as part of the complete doors
entrance except for general purpose goods
lifts, for which the builder should supply the
sill support; and
b) Architrave, or finish surrounds to doors: if of
metal, these should be provided by the lift
maker, with back filling by the general
contractor and if of timber by the joinery
contractor.
As referred to in 11.5, facilities for the use of the main
contractor's crane should be provided to assist in
installing heavy equipment. In addition to other
unloading facilities on site in the course of erection.
The main contractor should be instructed to include
these facilities in his own quantities.
Where the lift maker agrees to use mobile platforms
in place of lift well scaffolding, the general contractor
should provide 400/440 V 3-phase and 200/220 V
single-phase supply in the lift shaft to operate such
equipment, the supply to terminate at the position in
the lift well required by the lift maker.
These mobile platforms are limited in use for erection
personnel and the transportation of light equipment only,
but use of crane will also be necessary to assist in the
installation of the heavy machinery and also in the initial
installation of the mobile platform equipment.
10.5 Site Programme
The enquiry should indicate as accurately as possible
the contract programme as it affects the lift maker, in
particular the target date for lift completion, and the
date when the lift site will be prepared and the
availability of a crane.
11 ACCEPTANCE OE TENDER
SUBSEQUENT PROCEDURE
11.1 General
AND
The procedure indicated below particularly relates to
the most usual case, where the lift maker is a sub-
contractor.
11.2 Order
The main contractor is instructed to place an order with
the selected lift maker. If alternative schemes have been
offered, the order should clearly indicate which has
been accepted.
11.3 Programme
As noted in 10.5 the programme should have been
indicated as accurately as possible at the time of
enquiry. At the time of order, the programme for
manufacture and installation of the lift should be
agreed.
The programme should cover each lift separately,
including dates such as:
a) The order date,
b) The date when the lift site will be ready,
c) The date for provision of lift electricity
supplies, and
d) The lift completion date.
The period between order and delivery of material falls
into two stages: first the finalizing of details and
secondly the actual production of the equipment when
depends on the first stage. Within the first stage, other
dates may need to be considered, such as:
a) All relevant building information available,
b) Submission of lift maker* s drawings,
c) Approval of drawings, and
d) Final selection of finishes.
Information relevant to programming the site work can
be found in other clauses of this Section, such as in 12
and 13.
11.4 Drawings
Following order, the lift maker should supply drawings
showing builder's work required, together with point
loadings. To enable these to be prepared, the
purchaser's representative should furnish the relevant
detail building drawings.
11.5 Approval of Drawings
The purchaser's representative should give written
approval of the drawings (after modification if
necessary), at the same time asking for such additional
copies (up to five of each drawing) as he requires for
distribution to other parties concerned.
11.6 Selection of Finishes
Where the contact provides for the purchaser's choice
of decorative finishes, colours, etc, the decisions should
be communicated by the purchaser's representative as
early as possible, and preferably not later than the time
of approval of drawings.
11.7 Electricity Supplies to Lift
Operation of the machine under power is required from
a comparatively early stage of installation for the most
efficient working, and supplies should be furnished
PART 8 BUILDING SERVICES — SECTION 5 INSTALLATION OF LIFTS AND ESCALATORS
37
accordingly. Whilst temporary supplies may be
sufficient for erection purposes, final testing and setting
up can only be carried out with the permanent supplies
connected. For this reason the timely provision of the
permanent supplies is important.
12 CO-ORDINATION OF SITE WORK
12.1 Preparatory Work on Site
It is customary for the lift maker to make periodic visits
to the site before his starting date to check progress on
the lift well construction and discuss relevant matters
with the contractor. The lift maker should assure
himself that all building work has been completed in
accordance with his requirements.
Immediately, before the time for lift erection to
commence the lift maker should check that site
conditions are fit to permit erection to proceed.
Building work to be completed before lift erection
starts includes the following:
a) Pit lift well and machine room complete and
weather tight. Pit dry and watertight including
tanking if necessary and clear of rubbish.
NOTE — In certain systems building and buildings
of over 10 floors, it may be necessary by prior
agreement to start erection before the top portion of
the lift well has been constructed, in which case the
general contractor should temporarily deck out and
waterproof.
b) Preparation for lift fixings in pit, lift well and
machine room complete. If built-in wall
inserts are used, these should be placed
accurately and slots cleared of any seepage
of concrete.
c) Steelwork items finally grouted or otherwise
fixed in position after checking for correct
position by the lift maker (for example lift
well trimmers and machine beams).
d) Scaffolding in position, as arranged with
the lift maker, lift well etc. properly fenced
and guarded in accordance with current
regulation.
e) Entrance preparations completed, including
preparations for door frames, push boxes and
indicators. In many cases, progress can be
facilitated by omitting the front walls of the
lift well until the lift car, doors, etc. are
installed.
f) Datum line (in elevation) established at each
floor to enable the lift maker to set metal sills
and frames in relation to finished floor levels.
12.2 Delivery of Material
The lift maker should advise the contractor when
equipment is ready for despatch, so that the contractor
can make arrangements on site to receive and unload
with appropriate hoisting tackle, slings and supports,
as near as possible to the lift well.
12.3 Storage
Adequate provision should be made by the building
contractor for storing, protecting and preserving against
loss, deterioration or damage, all material on the site.
Attention is drawn to the adverse affect of damp
conditions on electrical equipment and on steel wire
ropes.
12.4 Site Meetings
For the successful progress of the work, full co-
operation among all parties is essential. In large sites,
regular meetings of such parties are beneficial.
Programmes for the constructional work in that part
of the building containing the lift should be made in
consultation among all parties concerned.
12.5 Service of Other Trades
The lift erector will require the services of joiners,
bricklayers and other trades as the work proceeds, and
it is essential that the lift erector should give due notice
to the building contractor of the demands to be made
on other trades, so that he can plan accordingly.
12.6 Scaffolding, Fencing Etc
Scaffolding timbers, rollers and similar items required
for the unloading and erection of the lift, and also for
the proper guarding and close fencing of the lift well
should be provided, erected and maintained by the
building contractor.
The lift well should not be used as a means of disposal
for rubbish from the upper floors. Such practice is
dangerous.
The lift well should be handed over to the lift contractor
complete, and no other trades should be allowed to
work above or below during the whole time of erection
of the lift, except by arrangement with the lift
contractor.
12.7 System Building Sites
If the building programme allows insufficient time for
lift erection in conventional fashion after the well is
completely built special procedures are needed. This
applies particularly to industrialized and multi-storey
buildings.
Methods differ in detail. In most cases however the
building contractor's crane is used to lower and
position pre-assembled batches of lift equipment into
the progressively rising top of the lift well.
38
NATIONAL BUILDING CODE OF INDIA
The building contractor should provide a suitable
portable cover to the completed portion of the lift well
in order to protect the lift erectors working below
against the weather and falling objects.
When the top of the well has been reached it is normal
to cap it immediately with a precase load bearing floor
slab on to which is lowered the pre-assembled machine
room equipment. It then remains for the building
contractor to complete and weatherproof the machine
room as swiftly as possible.
On all such projects as these the closest co-operation
between the building contractor and the lift maker is
essential.
12.8 Connecting to Power Supply
The lift maker should give prior warning to the building
contractor of the date the power supply to the lift is
required, so that suitable arrangements for connection
can be made.
13 PROCEDURE FOLLOWING TEST,
INCLUDING INSPECTION AND MAINTENANCE
13.1 Acceptance
The purchaser should make timely arrangements for
accepting the lift on completion of test, and for
insurance cover. Special arrangements (see 13.4) are
necessary if there is to be at interval before the lift
goes into normal service.
13.2 Guarantee and Servicing
Any guarantee provided by the lift maker should be
conditional upon the lift receiving regular and adequate
servicing, and should cover the free replacement of
parts which prove defective through reasons of fault,
materials or workmanship in the guarantee period,
which is generally twelve months.
To ensure the continuance of satisfactory and safe
operation, the purchaser (or building occupier) should
arrange for the completed lift to receive regular
servicing by competent persons at such intervals as
the type of equipment and intensity of operation
demand. Such service can be secured under a service
contract. It is desirable and normal for the lift maker
to be entrusted with the servicing during the guarantee
period of a new lift.
The scope of a service contract may be extended to
cover not only regular servicing, but also intermediate
service calls, repairs and replacement of worn parts.
The building owner should co-operate with the service
engineer, and should ensure that the equipment is
properly used, and that unauthorized persons are not
permitted to enter the lift well or machine rooms.
Particular attention should be paid to methods of
ensuring that lifts are not overloaded when they are used
in connection with furniture and equipment removals,
and internal redecoration and other similar activities,
which may be undertaken within the building.
13.3 Statutory Examinations
Lifts in certain premises are required by statutory
regulations to be examined at intervals, as specified
by the Lift Act, by a competent person, who is required
to report on a prescribed form. Such reports should
normally be kept in a register.
Statutory examinations are not a substitute for
servicing, the provision of statutory reports may be
specially included in a service contract or may be
arranged separately.
13.4 Lift not in Immediate Use (Shut Down
Maintenance)
When conditions do not permit a lift to be taken to
normal service immediately following completion and
acceptance, it should be immobilized. The main
contractor should take effective precautions against
damage especially to finishes, or damage to equipment
from dampness and builder's debris, until such time
as the lift is required.
A separate service contract should be made with the lift
maker to make regular visits during this period, to
inspect, lubricate and report on the condition of the lift.
A date should also be agreed with the lift maker from
which his guarantee period will commence.
13.5 Temporary Use of Lifts
If the purchaser intends to permit temporary use of a
lift by some other party, such as the building contractor,
before taking it into normal service, so that it is not
immobilized, then the responsibilities of those
concerned should be clearly defined and agreed. In
addition to the precautions noted in 13.4, temporary
insurance cover should be arranged.
If temporary use of lifts is envisaged, it should preferably
be given consideration at an early stage, having regard
to the conditions under which it is likely to take place.
13.6 Cleaning Down
Acceptance following test should include checking the
condition of decorative finishes, before the lift maker
leaves the site.
After a shut down (or temporary service) period, the
lift may require a further general cleaning down
immediately before taking into normal service. The
lift maker should be instructed accordingly to
undertake this work and if any accidental damage has
PART 8 BUILDING SERVICES — SECTIONS INSTALLATION OF LIFTS AND ESCALATORS
39
occurred to repair this at the same time. Both these
items should be the subject of extra costs.
14 ESCALATORS
14.1 Escalators are deemed essential where the
movement of people, in large numbers at a controlled
rate in the minimum of space, is involved, for example,
railway stations, airports, etc. In exhibitions, big
departmental stores and the like, escalators encourage
people to circulate freely and conveniently.
14.1.1 As the escalators operate at a constant speed,
serve only two levels and have a known maximum
capacity, the traffic study is rather easy. Provided the
population to be handled in a given time is known, it
is easy to predict the rate at which the population can
be handled.
14.1.2 For normal peak periods, the recommended
handling capacities for design purposes should be taken
as 3 200 to 6 400 persons per hour depending upon
the width of the escalator.
The number of persons that may be theoretically
carried by the escalator in 1 h can be calculated as
follows:
a) For determination of theoretical capacity it is
assumed that one step with an average depth
of 0.4 m can carry 1 person for a step width
of 0.6 m, 1.5 persons for a step width of 0.8 m
and 2 persons for a step width of 1.0 m.
b) The theoretical capacity then is:
3 600 x (rated speed in m/s x k)/0A
where
k= 1,1. 5, or 2 for 0.6, 0.8 and 1.0 m step
widths.
c) Some values calculated as per the above are:
Step
Width
Theoretical Capacity in
Persons/hour
0.6 m
0.8 m
1.0 m
0.5 m/s
speed
4 500
6 750
9 000
0.65 m/s
speed
5 850
8 775
11700
0.75 m/s
speed
6 750
10 125
13 500
14.2 Essential Requirements
14.2.1 Angle of inclination of an escalator from the
horizontal shall not exceed 30°, but for rises not
exceeding 6 m and rated speed not exceeding 0.5 m/s
the angle of inclination is permitted to be increased up
to 35°.
14.2.1.1 The rated speed of the escalator shall not
exceed 0.75 m/s for an angle of inclination up to 30°
and 0.5 m/s for an escalator with an angle of inclination
of more than 30° but within 35°.
14.2.2 The horizontal distance (measured at right
angles to the direction of travel) between the balustrade
interior panellings at lower points shall be equal to or
less than the horizontal distance measured at points
higher up. The maximum distance between the
balustrade interior panelling at any point shall be
smaller than the distance between handrails.
14.2.3 The parts of the balustrade facing the steps shall
be smooth. Covers or strips not in the direction of travel
shall not project more than 3 mm. They shall? be
sufficiently rigid and have rounded or bevelled edges.
Covers or strips of such nature are not permitted at the
skirting. ^, .*
Cover joints in the direction of travel (in particular
between the skirting and balustrade interior panelling)
shall be arranged and formed in such a manner that
the risk of trapping is reduced to a minimum.
Gaps between interior panels of the balustrade shall
not be wider than 4 mm. The edges shall be rounded
off or bevelled. The balustrade interior paneling shall
have adequate mechanical strength and rigidity. When
a force of 500 N is applied at any point of the paneling
at right angles on a area of 2 500 mm 2 . There shall
be no gap greater than 4 mm and no permanent
deformation (setting tolerances are permitted).
The use of glass for balustrade interior panelling is
permitted with the approval of the Authority; further,
provided it is splinter free one layer safety (tempered)
glass and has sufficient mechanical strength and
rigidity. The thickness of the glass shall not be less
than 6 mm.
14.2.3.1 There shall be no abrupt changes in the width
between the balustrades on the two sides of the
escalator. Where a change in width is unavoidable, such
change shall not exceed 8 percent of the greatest width.
In changing the direction of the balustrades resulting
from a reduction in width the maximum allowable
angle of change in balustrades shall not exceed 15°
from the line of the escalator travel.
14.2.3.2 Where the skirting of the escalator is placed
beside the steps the horizontal clearance shall not
exceed 4 mm at either side and 7 mm for the sum of
the clearances measured at both sides at two directly
opposite points.
14.2.3.3 Where the building obstacles can cause
injuries appropriate preventive measures shall be taken.
In particular, at floor intersections and on criss-cross
escalators, a vertical obstruction of not less than 0.3 m
in height (not presenting any sharp cutting edge, for
example as an imperforate triangle) shall be placed
40
NATIONAL BUILDING CODE OF INDIA
above the balustrade decking. It is not necessary to
comply with this requirement when the distance
between the centreline of the handrail and any obstacle
is equal to or greater than 0.5 m.
For escalators arranged adjacent to one another either
parallel or criss-cross the distance between the edges
of the handrails shall not be less than 120 mm.
14.2.4 Handrails
14.2.4.1 Each balustrade shall be provided with a
handrail moving in the same direction and at
substantially the same speed as the steps.
14.2.4.2 Each moving handrail shall extend at normal
handrail height not less than 300 mm beyond the line
of points of combplate teeth at the upper and lower
landings.
14.2.4.3 Hand or finger guards shall be provided at
the points where the handrails enters the balustrade.
14.2.4.4 The width of the handrail shall be between
70 mm and 120 mm. The distance between the handrail
and the edge of the balustrade shall not exceed 50 mm.
The distance between centreline of handrails shall not
exceed the distance between the skirtings by more than
0.45 m.
14.2.5 Step Treads
14.2.5.1 The step depth in the direction of travel shall
not be less than 0.38 m.
14.2.5.2 The surface of the step treads shall have
grooves in the direction of movement, with which the
teeth of the combs mesh. They shall be sensibly
horizontal in the usable area of the escalator.
The width of the grooves shall be at least 5 mm and
not exceed 7 mm. The depth of the grooves shall not
be less than 10 mm. The web width shall be at least
2.5 mm and not exceed 5 mm.
14.2.6 Landing
The landing area of escalators shall have a surface that
provides a secure foot hold for a minimum distance of
0.85 m measured from the root of the comb teeth.
Exempted from this are the combs.
14.2.7 Combplates
There shall be a combplate at the entrance and at the
exit of every escalator. The combplate teeth shall be
meshed with and set into the slots in the tread surface
so that the points of the teeth are always below the
upper surface of the treads. Combplates shall be
adjustable vertically.
14.2.8 Trusses or Girders
The truss or girder shall be designed to safety sustain
the steps and running gear in operation. In the event of
failure of the track system it shall retain the running
gear in its guides.
14.2.9 Step Wheel Tracks
This shall be designed to prevent displacement of steps
and running gear if a step chain breaks.
14.2.10 Driving Machine, Motor and Brake
14.2.10.1 The driving machine shall be connected to
the main drive shaft by toothed gearing, a coupling, or
a chain.
14.2.10.2 An electric motor shall not drive more than
one escalator.
14.2.10.3 Each lift shall be provided with an
electrically released, mechanically applied brake
capable of stopping the up or down travelling escalator
with any load up to rated load. This brake shall be
located either on the driving machine or on the main
drive shaft.
Where a chain is used to connect the driving machine
to the main drive shaft, a brake shall be provided on
this shalt, it is not required that this brake be of the
electrically released type if an electrically released
brake is provided on the driving machine.
14.2.10.4 Speed governor
Escalators shall be equipped in such a way that they
stop automatically before the speed exceeds 1.2 times
the rated speed. Where speed control devices are used
for this purpose they shall have switched off the
escalator before the speed exceeds 1.2 times the rated
speed. It is permissible to disregard this requirement
in case of ax. motors with a non-friction connection
with the drive for the steps and whose slip does
not exceed 10 percent if thereby overspeed is
prevented.
14.2.10.5 For operation and safety devices, electrical
work, precautions and tests, reference may be made to
good practice [8-5(1 1)].
PART 8 BUILDING SERVICES — SECTIONS INSTALLATION OF LIFTS AND ESCALATORS
41
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and 'accepted standards'
in the fulfillment of the requirements of the Code. The
latest version of a standard shall be adopted at the time
of enforcement of the code. The standards listed may
be used by the Authority as a guide in conformance
with the requirements of the referred clauses in the
Code.
IS No.
IS No.
(1) 14671 : 1999
(2) 14665
(Part 1) : 2000
(Part3/Secl&2):
2000
(Part4/Sec 1 to 9):
2001
(3) 14665 (Part 4/
Sec 1 to 9): 2001
Title
Code of practice for
installation and maintenance
of hyraulic lifts
Electric traction lifts:
Guidelines for outline
dimensions of passenger,
goods, service and hospital
lifts
Safety rules, Section 1
Passenger and goods lifts,
Section 2 Service lifts
Components, Section 1 Lift
Buffers, Section 2 Lift guide
rails and guide shoes,
Section 3 Lift carframe,
car, counterweight and
suspension, Section 4 Lift
safety gears and governors,
Section 5 Lift retiring cam,
Section 6 Lift doors and
locking devices and contacts,
Section 7 Lift machines and
brakes, Section 8 Lift wire
ropes, Section 9 Controller
and operating devices
Electric traction lifts:
Components, Section 1 Lift
buffers, Section 2 Lift guide
rails and guide shoes,
Section 3 Lift carframe,
(4) 14665 (Part 3/
Sec 1 & 2) : 2000
(5) 14665 (Part 2/
Sec 1 & 2) : 2000
(6) 962 : 1989
(7) 2309 : 1989
(8) 1950 : 1962
(9) 14665 (Part 3/
Sec 1 & 2) : 2000
(10) 3043 : 1987
(11)4591 : 1968
Title
car, counterweight and
suspension, Section 4 Lift
safety gears and governors,
Section 5 Lift retiring cam,
Section 6 Lift doors and
locking devices and contacts,
Section 7 Lift machines and
brakes, Section 8 Lift wire
ropes, Section 9 Controller
and operating devices
Electric traction lifts: Part 3
Safety rules, Section 1
Passenger and goods lifts,
Section 2 service lifts
Electric traction lifts: Part 2
Code of practice for
installation, operation and
maintenance, Section 1
Passenger and goods lifts,
Section 2 Service lifts
Code of practice for
architectural and building
drawings (second revision)
Code of practice for the
protection of buildings and
allied structures against
lightning (second revision)
Code of practice for sound
insulation of non-industrial
buildings
Electric traction lifts: Part 3
Safety rules — Section 1
Passenger and goods lifts,
Section 2 Service lifts
Code of practice for earthing
Code of practice for
installation and maintenance
of escalators
42
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 9 PLUMBING SERVICES
Section 1 Water Supply, Drainage and Sanitation
(Including Solid Waste Management)
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 GENERAL
4 WATER SUPPLY
5 DRAINAGE AND SANITATION
6 SOLID WASTE MANAGEMENT
ANNEX A APPLICATION FORM FOR TEMPORARY/PERMANENT SUPPLY
OF WATER/FOR ADDITIONS AND/OR ALTERATIONS FOR
SUPPLY OF WATER
ANNEX B FORM FOR LICENCED PLUMBER'S COMPLETION
CERTIFICATE
ANNEX C APPLICATION FOR DRAINAGE OF PREMISES
ANNEX D FORM FOR DETAILED DESCRIPTION OF WORK AND
SPECIFICATION OF MATERIALS
ANNEX E FORM FOR LICENCED PLUMBER'S COMPLETION
CERTIFICATE
ANNEX F NOMOGRAM OF HAZEN AND WILLIAM'S EQUATION
LIST OF STANDARDS
7
7
16.
18
41
79
81
82
83
83
85
86
87
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
This Section covers the requirements of both water supply as well as drainage and sanitation.
The water supply provisions covered in this Section encompass the requirements of water supply, plumbing
connected to public water supply, design of water supply systems, principles of conveyance and distribution of
water within the premises, hot water supply system, inspection and maintenance of water supply systems. It also
covers design of water supply systems in high altitudes and/or sub-zero temperature regions.
The drainage and sanitation provisions covered in this Section encompass the drainage and sanitation requirements
of buildings, design, construction and maintenance of drains inside buildings and from the buildings up to the
connection to the public sewer, private sewer, individual sewage disposal system, cesspool or to other approved
point of disposal/treatment work. It also covers drainage systems peculiar to high altitudes and/or sub-zero
temperature regions of the country.
In the first version of the Code formulated in 1970, three separate sections of Part 9 Plumbing Services, were
brought out, namely, Section 1 Water Supply, Section 2 Drainage and Sanitation, and Section 3 Gas Supply.
These sections were subsequently revised in 1983. The major changes incorporated in the first revision in Section 1
Water Supply, were;
a) Rationalization of definitions and addition of definitions for more terms.
b) Universal pipe friction diagram and nomogram of Hazen and Willam' s equation were added for discharge
computation, deleting the discharge curves based on Chezy's formula.
c) A detailed clause giving guidance on the design of water supply system for multi-storeyed buildings
was introduced.
d) In regard to storage tanks for flushing, the requirements were modified to indicate that no separate
storage need be provided for flushing and domestic purposes for health reasons and a single storage
tank may be provided.
e) Provisions relating to domestic hot water supply installations were modified/amplified.
f) A detailed clause covering recommendations to be considered while planning and designing water supply
systems peculiar to high altitude and/or sub-zero temperature regions of the country, were introduced.
g) Requirements relating to inspection, testing and maintenance applicable to hot water supply system
were added.
The major changes incorporated in the first revision in Section 2 Drainage and Sanitation were:
a) Rationalization of definitions.
b) The requirements for fitments for drainage and sanitation in the case of buildings other than residences
have been modified.
c) A table for sanitation facilities in fruit and vegetable markets has been added.
d) A table giving detailed guidance regarding the selection of plumbing system, depending on the nature
of drainage load in buildings and height of buildings, has been introduced.
e) Provision relating to safeguards to be adopted in single stack system have been amplified.
f) The values of gradients, pipe sizes and the corresponding discharges have been modified.
g) Sizes of manholes/inspection chambers have been rationalized.
h) The sizing of rain water pipe for roof drainage has been modified to take into account rainfall intensities
and recommend sizes on a more rational basis,
j) Provisions for drainage and sanitation system peculiar to high altitudes and/or sub-zero temperature
regions of the country have been added,
k) Requirements of the refuse chute system have been covered.
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION 3
As a result of experience gained in implementation of 1983 version of the Code and feedback received as well as
revision of some of the standards based on which this Section was prepared, a need to revise this Section was felt.
This revision has, therefore, been prepared to take care of these. In this revision, the erstwhile two sections have
been merged and a combined and comprehensive section, namely Section 1 Water Supply, Drainage and Sanitation
(Including Solid Waste Management), is being brought out. This elaborate restructuring has been done to make
the document comprehensive and more user friendly, and at the same time to avoid repetition of common
provisions. Gas Supply is now being brought out as Section 2. The significant changes incorporated in this
combined revision on Water Supply, Drainage and Sanitaton include:
In Water Supply provisions:
a) Provision of water supply requirement has been modified.
b) A new clause on water supply for other purposes has been added.
c) A new clause on quality of water has been added which also includes a sub-clause on waste water
reclamation.
d) The provision regarding storage of water has been modified and guidelines for calculating storage
capacity have been introduced.
e) In design of distribution system provisions for discharge computation has been modified to include
designed consumer pipes based on fixtures unit also taking into account probable simultaneous demand
instead of earlier computation based on Reynold's Number.
f) An alternate option of variable speed drive pumping system to hydropneumatic system has been
introduced.
g) A new clause on backflow prevention has been added.
h) Provision for suitability of galvanized mild steel tanks on the basis of pH of the water has been added.
j) Types of hot water heater has been extended.
k) Restructuring of the Section has been done to make it more user friendly.
In Drainage and Sanitation:
a) Rationalization and addition of new definitions under terminology.
b) Certain basic principles for water supply and drainage have been enunciated.
c) A new clause on sanitary appliances has been added.
d) Tables 1 to 14 of the existing version, regarding drainage and sanitation requirement have been updated.
e) Additional requirements under layout clause of design considerations have been added.
f) Provisions regarding choice of plumbing systems have been modified and rationalized.
g) New clause on drain appurtenances having details on trap, floor drain and cleanout has been added.
h) Provisions on indirect wastes, special wastes (covering laboratory wastes, infected wastes, research
laboratory wastes, etc), grease traps, oil interceptors, radio-active wastes, etc have been incorporated,
j) Manhole details on size have been revised and construction clause has been enhanced.
k) Provisions on rain water harvesting have been included,
m) The minimum rainfall intensity which is drain design basis for discharge of storm water drain into a
public storm water drain, has been revised to 50 mm/hour,
n) The table for Sizing of Rain Water Pipes for Roof Drainage has been modified with inclusion of rainfall
data which were not available in the existing version,
p) Figure on detail of subsoil drainage has been included,
q) Details on Support/Protection of Pipes has been added.
This revision also incorporates for the first time the provisions on solid waste management.
This Section has been based largely on the following Indian Standards:
IS No. Title
Mil: 1993 Code of basic requirements for water supply, drainage and sanitation {fourth
revision)
1742 : 1983 Code of practice for building drainage (second revision)
4 NATIONAL BUILDING CODE OF INDIA
IS No. Title
2065 : 1983 Code of practice for water supply in buildings (second revision)
4111 (Part 1) : 1986 Code of practice for ancillary structures in sewage system: Part 1 Manholes (first
revision)
5329 : 1983 Code of practice for sanitary pipe work above ground for buildings (first revision)
6295 : 1986 Code of practice for water supply and drainage in high altitudes and or sub-zero
temperature regions (first revision)
7558 : 1974 Code of practice for domestic hot water installations
12183 (Part 1) : 1987 Code of practice for plumbing in multi-storeyed buildings: Part 1 Water supply
A reference to SP 35 : 1987 'Handbook on water supply and drainage' may be useful, from where also, assistance
has been derived.
All standards, whether given herein above or cross referred to in the main text of this Section, are subject to
revision. The parties to agreement based on this Section are encouraged to investigate the possibility of applying
the most recent editions of the standards.
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
NATIONAL BUILDING CODE OF INDIA
PART 9 PLUMBING SERVICES
Section 1 Water Supply, Drainage and Sanitation
(Including Solid Waste Management)
1 SCOPE
1.1 This Section covers the basic requirements of
water supply for residential, business and other types
of buildings, including traffic terminal stations. This
Section also deals with general requirements of
plumbing connected to public water supply and design
of water supply systems.
1.1.1 This Section does not take into consideration the
requirements of water supply for industrial plants and
processes, which have to be provided for separately.
It also does not provide the requirements of water
supply for other purposes, such as fire fighting, and
street cleaning.
1.2 This Section also covers the design, layout,
construction and maintenance of drains for foul water,
surface water and subsoil water and sewage; together
with all ancillary works, such as connections, manholes
and inspection chambers used within the building and
from building to the connection to a public sewer,
private sewer, individual sewage-disposal system, cess-
pool, soakaway or to other approved point of disposal/
treatment work.
NOTE — A sanitary drainage system consists of a building
sewer, a building drain, a soil and/or waste stack, horizontal
branches or fixture drain, and vents. The sanitary drainage of a
large building may have a number of primary and secondary
branches, and several soil and/or waste stacks, each of them in
turn may have a number of horizontal branches.
2 TERMINOLOGY
2.1 For the purpose of this Section, the following
definitions shall apply.
2.1.1 Access Panel — Removable panel mounted in a
frame, normally secured with screws and mounted in
a wall or ceiling, to provide access to concealed
appurtenances or items which may require maintenance.
2.1.2 Air Gap — The distance between the lowest
point of a water inlet or feed pipe to an appliance and
the spill-over level (or the overflowing level) of the
appliance.
2.1.3 Air Valve — A valve that releases air from a
pipeline automatically without loss of water, or
introduce air into a line automatically if the internal
pressure becomes less than that of the atmosphere.
2.1.4 Authority Having Jurisdiction — The Authority
which has been created by a statute and which for the
purpose of administering the Code/Part may authorize
a committee or an official to act on its behalf;
hereinafter called the * Authority \
2.1.5 Available Head — The head of water available
at the point of consideration due to mains' pressure or
overhead tank or any other source of pressure.
2.1.6 Back Siphonage — The flowing back of used,
contaminated, or polluted water from a plumbing
fixture or vessel into a water supply due to a reduced
pressure in such pipe (see Backflow).
2.1.7 Back Up — A condition where the wastewater
may flow back into another fixture or compartment
but not back into the potable water system.
2.1.8 Backflow
a) The flow of water or other liquids, mixtures
or substances into the distributing pipes of a
system of supply of potable water from any
source or sources other than its intended
source.
b) The flow of a liquid in a direction reverse of
that intended.
2.1.9 Backflow Prevention Device — Any approved
measure or fitting or combination of fittings specifically
designed to prevent backflow or backsiphonage in a
water service.
2.1.10 Barrel — This portion of a pipe in which
the diameter and wall thickness remain uniform
throughout.
2.1.11 Base — The lowest portion or lowest point of
a stack of vertical pipe.
2.1.12 Battery of Fixtures — Any group of two or more
similar adjacent fixtures which discharge into a
common horizontal waste or soil pipe.
2.1.13 Bedding — The material on which the pipe is
laid and which provides support for the pipe. Bedding
can be concrete, granular material or the prepared
trench bottom.
2.1.14 Benching — Slopping surfaces constructed on
PART 9 PLUMBING SERVICES — SECTION 1 WATER Si' PPLY, DRAINAGE AND SANITATION
either side of channels at the base of a manhole or
inspection chamber for the purpose of confining the
flow of sewage, avoiding the accumulation of deposits
and providing a safe working platform.
2.1.15 Branch
a) Special form of sewer pipe used for making
connections to a sewer or water main. The
various types are called T\ *Y\ T-Y\
double Y and V branches, according to their
respective shapes.
b) Any part of a piping system other than a main
or stack.
2.1.16 Branch Soil Pipe (BSP) — A pipe connecting
one or more soil appliances to the main soil pipe.
2.1.17 Branch Soil Waste Pipe (BSWP) — A pipe
connecting one or more soil and/or waste appliances
to the main soil waste pipe (one pipe system).
2.1.18 Branch Ventilating Pipe (BVP) — A pipe, one
end of which is connected to the system adjacent to
the trap of an appliance and the other to a main
ventilating pipe or a drain- ventilating pipe. It is fitted
to prevent loss of water seal from a trap owing to partial
vacuum, back-pressure, or surging caused by air
movement within the pipe system. It also provides
ventilation for the branch waste pipe.
2.1.19 Branch Waste Pipe (BWP) — A pipe connecting
one or more waste appliances to the main waste pipe.
2.1.20 Building Drain, Combined — A building drain
which conveys both sewage and storm water or other
drainage.
2.1.21 Building Drain, Sanitary — A building drain
which conveys sewage and sullage only.
2.1.22 Building Drain, Storm — A building drain
which conveys storm water or other drainage but no
sewage.
2.1.23 Building Sewer — That part of the horizontal
piping of a drainage system which extends from the
end of the building drain and which receives the
discharge of the building drain and conveys it to a
public sewer, private sewer, individual sewage-
disposal system or approved point of disposal.
2.1.24 Building Sub-Drain — That portion of a
drainage system which cannot drain by gravity in the
building sewer.
2.1.25 Building Trap — A device, fitting or assembly
of fittings installed in the building drain to prevent
circulation of air between the drainage of the building
and the building sewer. It is usually installed as ranning
trap.
2.1.26 Cesspool
a) An underground chamber for the reception
* and storage of foul water, the contents of
which are periodically removed for disposal.
b) A box-shaped receiver constructed in a roof
or gutter for collecting rainwater which then
passes into a rainwater pipe connected
thereto.
2.1.27 Chair — A bed of concrete or other suitable
material on the trench floor to provide a support for
the pipes at intervals.
2.1 .28 Channel — The open waterway through which
sewage, storm water or other liquid wastes flow at the
invert of a manhole or an inspection chamber.
2.1.29 Chute — A vertical pipe system passing from
floor to floor provided with ventilation and inlet
openings for receiving refuse from successive floors
and ending at the ground floor on the top of the
collecting chambers.
2.1.30 Cistern — A fixed container for water in which
water is at atmospheric pressure. The water is usually
supplied through a float operated valve.
2.1.31 Cleaning Eye — An access opening in a pipe
or pipe fitting arranged to facilitate the cleaning of
obstructions and fitted with removable cover.
2.1.32 Clear Waste Water — Cooling water and
condensate drainage from refrigeration and air
conditioning equipment, cooled condensate from steam
heating systems, cooled boiler blow-down water, waste
water drainage from equipment rooms and other areas
where water is used without an appreciable addition
of oil, gasoline, solvent, acid, etc, and treated effluent
in which impurities have been reduced below a
minimum concentration considered harmful.
2.1.33 Collection Chamber — A compartment
situated at the lower end of the chute for collecting
and housing the refuse during the period between two
successive cleanings.
2.1.34 Communication Pipe — That part of a service
pipe which vests in the water undertakes. It starts at
the water main and terminate at a point which differs
according to the circumstances of the case.
2.1.35 Connection — The junction of a foul water
drain, surface water drain or sewer from building or
8
NATIONAL BUILDING CODE OF INDIA
GROUND
STORAGE
TANK
MUNICIPAL
LIMIT
NOTE — The illustration is not intended to indicate recommended positions of underground storage tank
(where provided), pipes, etc and this will depend on local situations.
Fig. 1 Typical Sketch for Identification of Different Types of
Water Supply Pipes
building with public sewer treatment works, public
sewer, private sewer, individual sewage-disposal
system, cess pool, soakaway or to other approved point
of disposal/treatment work.
2.1.36 Consumer — Any person who uses or is
supplied water or on whose application such water is
supplied by the Authority.
2.1.37 Consumer's Pipe — The portion of service pipe
used for supply of water and which is not the property
of the Authority (see Fig. 1).
2.1.38 Cover
a) A removable plate for permitting access to a
pipe, fitting, vessel or appliance.
b) The vertical distance between the top of the
barrel of a buried pipe or other construction
and the surface of the ground.
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
2.1.39 Cross-Connection — A connection between
two normally independent pipelines which permits
flow from either pipeline into the other.
2.1.40 Crown of Trap
inside of a trap outlet.
The topmost point of the
2.1.41 Deep Manhole — A manhole of such depth
that an access shaft is required in addition to the
working chamber.
2.1.42 Depth of Manhole — The vertical distance from
the top of the manhole cover to the outgoing invert of
the main drain channel.
2.1.43 Diameter — The nominal internal diameter of
pipes and fittings.
2.1.44 Direct Tap — A tap which is connected to a
supply pipe and is subject to pressure from the water
main.
2.1.45 Downtake Tap — A tap connected to a system
of piping not subject to water pressure from the water
main.
2.1.46 Drain — A conduit, channel or pipe for the
carriage of storm water, sewage, waste water or other
water-borne wastes in a building drainage system.
2.1.47 Drain Ventilating Pipe (DVP) — A pipe
installed to provide flow of air to or from a drain to
prevent undue concentration of foul air in the drain.
The main soil pipe or main waste pipe may serve as
drain ventilating pipe wherever their upper portions,
which do not receive discharges, are extended to the
roof level and let open to air.
2.1.48 Drainage — The removal of any liquid by a
system constructed for the purpose.
2.1.49 Drainage Work — The design and construction
of a system of drainage.
2.1.50 Drop Connection — A length of conduit
installed vertically immediately before its connection
to a sewer or to another drain.
2.1.51 Drop Manhole — A manhole installed in a
sewer where the elevation of the incoming sewer
considerably exceeds that of the outgoing sewer; a
vertical waterway outside the manhole is provided to
divert the waste from the upper to the lower level so
that it does not fall freely into the manhole except at
peak rate of flow.
2.1.52 Effective Opening — The minimum cross-
sectional area at the point of water supply, measured
or expressed in terms of:
a) the diameter of a circle; and
b) the diameter of a circle of equivalent cross-
sectional area, if the opening is not circular.
2.1.53 Feed Cistern — A storage vessel used for
supplying cold water to a hot water apparatus, cylinder
or tanks.
2.1.54 Fittings — Fittings shall mean coupling, flange,
branch, bend, tees, elbows, unions, waste with plug, P
or S trap with vent, stop ferrule, stop tap, bib tap, pillar
tap, globe tap, ball valve, cistern storage tank, baths,
water-closets, boiler, geyser, pumping set with motor
and accessories, meter, hydrant, valve and any other
article used in connection with water supply, drainage
and sanitation.
2.1.55 Fixture Unit — A quantity in terms of which
the load producing effects on the plumbing system of
different kinds of plumbing fixtures is expressed on
some arbitrarily chosen scale.
2.1.56 Fixture Unit Drainage — A measure of
probable discharge into the drainage system by various
types of plumbing fixtures. The drainage fixture unit
value for a particular fixture depends on its volume
rate of drainage discharge, on the time duration of a
single drainage operation and on the average time
between successive operations.
2.1.57 Float Operated Valve — Ball valves or ball
taps and equilibrium valves operated by means of a
float.
2.1.58 Flushing Cistern — A cistern provided with a
device for rapidly discharging the contained water and
used in connection with a sanitary appliance for the
purpose of cleaning the appliance and carrying away
its contents into a drain.
NOTE — The nominal size of a cistern is the quantity of water
discharged per flush.
2.1.59 Formation — - The finished level of the
excavation at the bottom of a trench or heading
prepared to receive the permanent work.
2.1.60 French Drain or Rubble Drain — A shallow
trench filled with coarse rubble, clinker, or similar
material with or without field drain pipes.
2.1.61 Frost Line — The line joining the points of
greatest depths below ground level up to which the
moisture in the soil freezes.
2.1.62 General Washing Place — A washing place
provided with necessary sanitary arrangement and
common to more than one tenement.
10
NATIONAL BUILDING CODE OF INDIA
2.1.63 Geyser — An apparatus for heating water with
supply control on the inlet side and delivering it from
an outlet.
2.1.64 Gully Chamber — The chamber built of
masonry round a gully trap for housing the same.
2.1.65 Gully Trap — A trap provided in a drainage
system with a water seal fixed in a suitable position to
collect waste-water from the scullery, kitchen sink,
wash basins, baths and rain water pipes.
2.1.66 Haunching — Outward sloping concrete
support to the sides of a pipe or channel above the
concrete bedding.
2.1.67 Heel Rest Bend or Duck-Foot Bend — A bend,
having a foot formed integrally in its base, used to
receive a vertical pipe.
2.1.68 High Altitudes — Elevations higher than
1 500 m above mean sea level (MSL).
2.1.69 Highway Authority — The public body in
which is vested, or which is the owner of, a highway
repairable by the inhabitants collectively; otherwise
the body or persons responsible for the upkeep of the
highway.
2.1.70 Horizontal Pipe — Any pipe of fitting which
makes an angle of more than 45° with the vertical.
2.1.71 Hot Water Tank — A vessel for storing hot
water under pressure greater than atmospheric pressure.
2.1.72 Inlet Hopper — A receptacle fitting for receiving
refuse from each floor and dropping it into the chute.
2.1.73 Inspection Chamber — A water-tight chamber
constructed in any house-drainage system which takes
wastes from gully traps and disposes of to manhole
with access for inspection and maintenance.
2.1.74 Interceptor — A device designed and installed
so as to separate and retain deleterious, hazardous or
undesirable matter from normal wastes and permit
normal sewage or liquid wastes to discharge into the
disposal terminal by gravity.
2.1.75 Interceptor Manhole or Interceptor Chamber
— A manhole incorporating an intercepting trap and
providing means of access thereto.
2.1.76 Invert — The lowest point of the internal
surface of a pipe or channel at any cross-section.
2.1.77 Junction Pipe — A pipe incorporating one or
more branches.
2.1.78 Lagging — Thermal insulation or pipes.
2.1.79 Licensed Plumber — A person licensed under
the provisions of this Code.
2.1.80 Main Soil Pipe (MSP) — A pipe connecting
one or more branch soil pipes to the drain.
2.1.81 Main Soil and Waste Pipe (MSWP) — A pipe
connecting one or more branch soil and waste pipes to
the drain.
2.1.82 Main Ventilating Pipe (MVP) — A pipe which
receives a number of branch ventilating pipes.
2.1.83 Main Waste Pipe(MWP) — A pipe connecting
one or more branch waste pipes to the drain.
2.1.84 Manhole — An opening by which a man may
enter or leave a drain, a sewer or other closed structure
for inspection, cleaning and other maintenance
operations, fitted with suitable cover.
2.1.85 Manhole Chamber — A chamber constructed
on a drain or sewer so as to provide access thereto for
inspection, testing or clearance of obstruction.
2.1.86 Non-Service Laterine — Other than 'service
latrine'.
2.1.87 Offset — A pipe fitting used to connect two
pipes whose axes are parallel but not in line.
2.1.88 Period of Supply — The period of the day or
night during which water supply is made available to
the consumer.
2.1.89 Pipe System — The system to be adopted will
depend on the type and planning of the building in
which it is to be installed and will be one of the
following:
a) Single stack system (see Fig. 2) — The one-
pipe system in which there is no trap
ventilation.
b) Single stack — Partially Vented — A via
media between the one-pipe system and the
single stack system (see one-pipe system,
partially ventilated).
c) One-pipe system (see Fig. 3) — The system
of plumbing in which the wastes from the
sinks, baths and wash basins, and the soil pipe
branches are all collected into one main pipe,
which is connected, directly to the drainage
system. Gully traps and waste pipes are
completely dispersed with, but all the traps
of the water closets, basins, etc, are
completely ventilated to preserve the water
seal.
d) One-pipe system — Partially vented (also
called single stack y partially ventilated) — A
system in which there is one soil pipe into
which all water closets, Baths, sinks, and
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
11
"TZL^
VERTICAL DISTANCE BETWEEN
LOWEST CONNECTION AND INVERT
-LARGE RADIUS BE NDS
wc
BUILDING
DRAIN
WB
WC lWB
WC AWB
WC -WB
WC» WATER CLOSET
S-StNK
WB-WASH BASIN
FT- FLOOR TRAP
Fl -FLOOR LEVEL
2A
2B
Fig. 2 Single Stack System — Main Feature of Design
basins discharge. In addition, there is a relief
vent, which ventilates only the traps of water
closets.
e) Two-pipe system (see Fig. 4) — The system
of plumbing in which soil and waste pipes
are distinct and separate. The soil pipes being
connected to the drain direct and waste pipes
through a trapped gully. All traps of all
appliances are completely ventilated in this
system.
2.1.90 Pipe Work — Any installation of piping with
its fittings.
2.1.91 Plumbing
a) The pipes, fixtures and other apparatus inside
a building for bringing in the water supply
and removing the liquid and water borne
wastes.
b) The installation of the foregoing pipes,
fixtures and other apparatus.
2.1.92 Plumbing System — The plumbing system
shall include the water supply and distribution pipes;
plumbing fittings and traps; soil, waste, vent pipes
and anti-siphonage pipes; building drains and building
sewers including their respective connections, devices
12
NATIONAL BUILDING CODE OF INDIA
TO
MANHOLE
TO
BUILDING
DRAIN
Fig. 3 Diagram of One-Pipe System
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
13
TO BUILDING
DRAIN
Fig. 4 Diagram of Two-Pipe System
14
NATIONAL BUILDING CODE OF INDIA
and appurtenances within the property lines of
the premises; and water-treating or water-using
equipment.
2.1.93 Potable Water — Water which is satisfactory
for drinking, culinary and domestic purposes and meets
the requirements of the Authority.
2.1.94 Premises — Premises shall include passages,
buildings and lands of any tenure, whether open or
enclosed, whether built on or not, and whether public
or private in respect of which a water rate or charge is
payable to the Authority or for which an application is
made for supply of water.
2.1.95 Puff Ventilation — The ventilation provided
tor waste traps in two-pipe system, in order to preserve
the water seal.
2.1.96 Residual Head — The head available at any
particular point in the distribution system.
2.1.97 Saddle — A purpose made fitting, so shaped
as to fit over a hole cut in a sewer or drain used to
form connections.
2.1.98 Sanitary Appliances — The appliances for the
collection and discharge of soil or waste matter.
2.1.99 Service Laterine — A laterine from which the
excreta are removed by manual agency and not by
water carriage.
2.1.100 Service Pipe — Pipe that runs between the
distribution main in the street and the riser in case of a
multi-storeyed building or the water meter in the case
of an individual house and is subject to water pressure
from such main.
2.1.101 Sewer — A pipe or conduit, generally closed,
but normally not flowing full for carrying sewage and/
or other waste liquids.
2.1.102 Slop Hopper (Slop Sink) — A hopper shaped
sink, with a flushing run and outlet similar to those of
a WC pan, for the reception and discharge of human
excreta.
2.1.103 Soakaway — A pit, dug into permeable ground
lined to form a covered perforated chamber or filled
with hard-core, to which liquid is led, and from which
it may soak away into the ground.
2.1.104 Soffit (Crown) — The highest point of the
internal surface of a sewer or culvert at any cross-
section.
2.1.105 Soil Appliances — A sanitary appliance for
the collection and discharge of excretory matter.
2.1.106 Soil Pipe — A pipe that conveys the discharge
of water closets or fixtures having similar functions,
with or without the discharges from other fixtures.
2.1.107 Soil Waste — The discharge from water
closets, urinals, slop hooper, stable yard or cowshed
gullies and similar appliances.
2.1.108 Stop-Cock — A cock fitted in a pipe line for
controlling the flow of water.
2.1.109 Stop Tap — Stop tap includes stop-cock, stop
valve or any other device for stopping the flow of water
in a line or system of pipes at will.
2.1.110 Storage Tank — A container used for storage
of water which is connected to the water main or tube-
well by means of supply pipe.
2.1.111 Sub-Soil Water — Water occurring naturally
in the sub-soil.
2.1.112 Sub-Soil Water Drain
a) A drain intended to collect and carry away
sub-soil water.
b) A drain intended to disperse into the sub-soil
from a septic tank.
2.1.113 Sub-Zero Temperature Regions — Regions
where temperatures fall below 0°C and freezing
conditions occur.
2.1.114 Sullage — See 2.1.129.
2.1.115 Supply Pipe — So much of any service pipe
as is not a communication pipe.
2.1.116 Supports — Hangers and anchors or devices
for supporting and securing pipe and fittings to walls,
ceilings, floors or structural members.
2.1.117 Surface Water — Natural water from the
ground surface, paved areas and roofs.
2.1.118 Surface Water Drain — A drain conveying
surface water including storm water.
2.1.119 Systems of Drainage
a) Combined system — A system in which
foul water (sewage) and surface water are
conveyed by the same sewers and drains.
b) Separate system — A system in which
foul water (sewage) and surface water are
conveyed by the separate sewers and
drains.
c) Partially separate system — A modification
of the separate system in which part of the
surface water is conveyed by the foul
(sanitary) sewers and drains.
2.1.120 Trade Effluent — Any liquid either with or
without particles of matter in suspension which is
wholly or in part produced in the course of any trade
or industry, at trade premise. It includes farm wastes
but does not include domestic sewage.
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
15
2.1.121 Trap — A fittings or device so designed and
constructed as to provide, when properly vented, a
liquid seal which will prevent the back passage of air
without materially affecting the flow of sewage or
waste water through it.
2.1.122 Vertical Pipe — Any pipe or fitting which is
installed in a vertical position or which makes an angle
or not more than 45° with the vertical.
2.1.123 Vent StacWVent Pipe — A vertical vent pipe
installed primarily for the purpose of proving
circulation of air to and from any part of the drainage
system. It also protects trap seals from excessive
pressure fluctuation.
2.1.124 Vent System — A pipe or pipes installed to
provide a flow of air to or from a drainage system or
to provide a circulation of air with in such system to
protect traps seals from siphonage and back-pressure.
2.1.125 Warning Pipe — An overflow pipe so fixed
that its outlet, whether inside or outside a building, is
in a conspicuous position where the discharge of any
water therefrom can be readily seen.
2.1.126 Wash-Out Valve — A device located at the
bottom of the tank for the purpose of draining a tank
for cleaning, maintenance, etc.
2.1.127 Waste Appliance — A sanitary appliance for
the collection and discharge of water after use for
ablutionary, culinary and other domestic purpose.
2.1.128 Waste Pipe — In plumbing, any pipe that
receives the discharge of any fixtures, except water-
closets or similar fixtures and conveys the same to the
house drain or soil or waste stack. When such pipe
does not connect directly with a house drain or soil
stack, it is called an indirect waste pipe.
2.1.129 Waste-Water (Sullage) — The discharge from
wash basins, sinks and similar appliances, which does
not contain human or animal excreta.
2.1.130 Water Main (Street Main) — A pipe laid by
the water undertakers for the purpose of giving a
general supply of water as distinct from a supply to
individual consumers and includes any apparatus used
in connection with such a pipe.
2.1.131 Water Outlet — A water outlet, as used in
connection with the water distributing system, is the
discharge opening for the water (a) to a fitting; (b) to
atmospheric pressure (except into an open tank which
is part of the water supply system); and (c) to any water-
operated device or equipment requiring water to
operate.
2.1.132 Water Seal — The water in a trap, which acts
as a barrier to the passage of air through the trap.
2.1.133 Water Supply System — Water supply system
of a building or premises consists of the water service
pipe, the water distribution pipes, and the necessary
connecting pipes, fittings, control valves, and all
appurtenances in or adjacent to the building or
premises.
2.1.134 Waterworks — Waterworks for public water
supply include a lake, river, spring, well, pump with
or without motor and accessories, reservoir, cistern,
tank, duct whether covered or open, sluice, water main,
pipe, culvert, engine and any machinery, land, building
or a thing used for storage, treatment and supply of
water.
3 GENERAL
3.1 Basic Principles
3.1.1 Potable Water
All premises intended for human habitation,
occupancy, or use shall be provided with supply of
potable water. This water supply shall not be connected
with unsafe water resources, nor shall it be subject to
the hazards of backflow.
3.1.2 Water Provision
Plumbing fixtures, devices and appurtenances shall be
provided with water in sufficient volume and at
pressures adequate to enable them to function properly
and without undue noise under normal conditions of
use.
There should be at least a residual head of 0.018 N/mm 2
at the consumer's tap.
NOTE — The residual head shall be taken at the highest/farthest
outlets in the building.
3.1.3 Water Conservation
Plumbing system shall be designed, installed and
adjusted to use the optimum quantity of water
consistent with proper performance and cleaning.
3.1.4 Safety Devices
Plumbing system shall be designed and installed with
safety devices to safeguard against dangers from
contamination, explosion, overheating, etc.
3.1.5 Plumbing Fixtures
It is recommended that each family dwelling unit
should have at least one water closet, one lavatory,
one kitchen wash place or a sink, and one bathing wash
place or shower to meet the basic requirements of
sanitation and personal hygiene.
3.1#6 Drainage System
The drainage system shall be designed, installed and
maintained to guard against fouling, deposit of solids
16
NATIONAL BUILDING CODE OF INDIA
and clogging and with adequate cleanouts so arranged
that the pipes may be readily cleaned.
3.1.7 Materials and Workmanship
The plumbing system shall have durable material, free
from defective workmanship and so designed and
installed as to give satisfactory service for its
reasonable expected life.
3.1.8 Fixture Traps and Vent Pipes
Each fixture directly connected to the drainage system
shall be equipped with a liquid seal trap. Trap seals
shall be maintained to prevent sewer gas, other
potentially dangerous or noxious fumes, or vemin from
entering the building. Further, the drainage system shall
be designed to provide an adequate circulation of air
in all pipes with no danger of siphonage, aspiration, or
forcing of trap seals under conditions of ordinary use
by providing vent pipes throughout the system.
3.1.9 Foul Air Exhaust
Each vent terminal shall extend to the outer air and be
so installed as to minimize the possibilities of clogging
and the return of foul air to the building, as it conveys
potentially noxious or explosive gases to the outside
atmosphere. All vent pipes shall be provided with a cowl.
3.1.10 Testing
The plumbing system shall be subjected to required
tests to effectively disclose all leaks and defects in the
work or the material.
3.1.11 Exclusion from Plumbing System
No substance that will clog or accentuate clogging of
pipes, produce explosive mixtures, destroy the pipes or
their joints, or interfere unduly with the sewage-disposal
process shall be allowed to enter the drainage system.
3.1.12 Light and Ventilation
Wherever water closet or similar fixture shall be
located in a room or compartment, it should be properly
lighted and ventilated.
3.1.13 Individual Sewage Disposal Systems
If water closets or other plumbing fixtures are installed
in buildings where connection to public sewer is not
possible, suitable provision shall be made for
acceptable treatment and disposal.
3.1.14 Maintenance
Plumbing systems shall be maintained in a safe and
serviceable condition.
3.1.15 Accessibility
All plumbing fixtures shall be so installed with regard
to spacing as to be accessible for their intended use
and for cleaning. All doors, windows and any other
device needing access within the toilet shall be so
located that they have proper access.
3.1.16 Fixture for Disabled
Special toilet fixtures shall be provided for the disabled
with required fixtures and devices.
3.1.17 Structural Safety
Plumbing system shall be installed with due regard to
preservation of the structural members and prevention
of damage to walls and other surfaces.
3.1.18 Protection of Ground and Surface Water
Sewage or other waste shall not be discharged into
surface or sub-surface water without acceptable form
of treatment.
3.2 Water Supply Connection
3.2.1 Application for Obtaining Supply Connection
Every consumer, requiring a new supply of water or
any extension or alteration to the existing supply shall
apply in writing in the prescribed form (see Annex A)
to the Authority.
3.2.2 Bulk Supply
In the case of large housing colonies or where new
services are so situated that it will be necessary for the
Authority to lay new mains or extend an existing main,
full information about the proposed housing scheme
shall be furnished to the Authority; information shall
also be given regarding their phased requirements of
water supply with full justification. Such information
shall include site plans, showing the layout of roads,
footpaths, building and boundaries and indicating
thereon the finished line and level of the roads or
footpaths and water supply lines and appurtenances.
3.2.3 Completion Certificate
On completion of the plumbing work for the water
supply system, the licensed plumber shall give a
completion certificate in the prescribed form (see
Annex B) to the Authority for getting the water
connection from the mains,
3.3 Drainage and Sanitation
3.3.1 Preparation and Submission of Plan
No person shall install or carry out any water-borne
sanitary installation or drainage installation or any
works in connection with anything existing or new
buildings or any other premises without obtaining the
previous sanction of the Authority.
The owner shall make an application in the prescribed
form (see Annex C) to the Authority to cany out such
a work.
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
17
3.3.2 Site Plan
A site plan of the premises on which the building is to
be situated or any such work is to be carried out shall
be prepared drawn to a scale not smaller than 1:500
(see Part 2 'Administration'). The site plan of the
building premises shall show:
a) the adjoining plots and streets with their names;
b) the position of the municipal sewer and the
direction of flow in it;
c) the invert level of the municipal sewer, the
road level, and the connection level of the
proposed drain connecting the building in
relation to the sewer,
d) the angle at which the drain from the building
joints the sewer; and
e) the alignment, sizes and gradients of all drains
and also of surface drains, if any.
A separate site plan is not necessary if the necessary
particulars to be shown in such a site plan are already
shown in the drainage plan.
3.3.3 Drainage Plan
The application (3.3.1) shall be accompanied by a
drainage plan drawn to a scale of not smaller than 1 : 1 00
and furnished along with the building plan (see Part 2
'Administration'). The plans shall show the following:
a) Every floor of the building in which the pipes
or drains are to be used;
b) The position, forms, level and arrangement
of the various parts of such building,
including the roof thereof;
c) All new drains as proposed with their sizes
and gradients;
d) Invert levels of the proposed drains with
corresponding ground levels;
e) The position of every manhole, gully, soil and
waste pipe, ventilating pipe, rain water pipe,
water-closet, urinal, latrine, bath, lavatory,
sink, trap or other appliances in the premises
proposed to be connected to any drain and
the following colours are recommended for
indicating sewers, waste water pipes, rain-
water pipes an existing work.
Description of Work
Sewers
Waste water pipes and
rain-water pipes
Existing work
Colour
Red
Blue
Black
f) The position of refuse chute, inlet hopper and
collection chamber.
3.3.3.1 In the case of an alteration or addition to an
existing building, this clause shall be deemed to be
satisfied if the plans as furnished convey sufficient
information for the proposals to be readily identified
with previous sanctioned plans and provided the
locations of tanks and other fittings are consistent with
the structural safety of the building.
3.3.3.2 The plans for the building drainage shall in
every case be accompanied by specifications for the
various items of work involved. This information shall
be supplied in the prescribed from given in Annex D.
3.3.4 In respect of open drains, cross-sectional details
shall be prepared to a scale not smaller than 1:50
showing the ground and invert levels and any
arrangement already existing or proposed for the
inclusion of any or exclusion of all storm water from
the sewers.
3.3.5 Completion Certificate
At the completion of the plumbing installation
work, the licensed plumber shall give a completion
certificate in the prescribed form, which is given in
Annex E.
3.4 Licencing/Registration of Plumbers
3.4.1 Execution of Work
The work which is required to be carried out under the
provisions of this Section, shall be executed only by a
licensed plumber under the control of the Authority
and shall be responsible to carry out all lawful
directions given by the Authority. No individual shall
engage in the business of plumbing unless so licensed
under the provisions of this Section.
3.4.1.1 No individual, firm, partnership or corporation
shall engage in the business of installing, repairing or
altering plumbing unless the plumbing work performed
in the course of such business is under the direct
supervision of a licensed plumber.
3.4.2 Examination and Certification
The Authority shall establish standards and procedure
for the qualification, examination and licensing of
plumbers and shall issue licences to such persons who
meet the qualifications thereof and successfully pass
the examination.
3.4.3 For guidelines for registration of plumbers
including the minimum standards for qualifications for
the grant of licences, reference may be made to good
practice [9-1(1)].
4 WATER SUPPLY
4.1 Water Supply Requirements for Buildings
4.1.1 Water Supply for Residences
A minimum of 70 to 100 litres per head per day may
18
NATIONAL BUILDING CODE OF INDIA
40 lphd, Min
70 to 100 lphd
100 to 150 lphd
be considered adequate for domestic needs of urban
communities, apart from non-domestic needs as
flushing requirements. As a general rule the following
rates per capita per day may be considered minimum
for domestic and non-domestic needs:
a) For communities with
population upto 20 000 and
without flushing system:
1 ) water supply through
standpost
2) water supply through
house service connection
b) For communities with
population 20 000 to
100 000 together with full
flushing system
c) For communities with
population above 100 000
together with full flushing
system
NOTE — The value of water supply given as 150 to 200
litres per head per day may be reduced to 135 litres per head
per day for houses for Lower Income Groups (LIG) and
Economically Weaker Section of Society (EWS), depending
upon prevailing conditions.
4.1.1.1 Out of the 150 to 200 litres per head per day,
45 litres per head per day may be taken for flushing
requirements and the remaining quantity for other
domestic purposes.
4.1.2 Water Supply for Buildings Other than Residences
Minimum requirements for water supply for buildings
other than residences shall be in accordance with
Table 1.
Table 1 Water Requirements for Buildings
Other than Residences
(Clause A A 2)
4.1.3 Water Supply Requirements of Traffic Terminal
Stations
The water supply requirements of traffic terminal
stations (railway stations, bus stations, harbours,
airports, etc) include provisions for waiting rooms and
waiting halls. They do not, however, include
requirements for retiring rooms. Requirements of water
supply for traffic terminal stations shall be according
to Table 2.
Table 2 Water Supply Requirements for
Traffic Terminal Stations
(Claude 4A3)
SI
No.
Nature of
Station/Terminal
Where Bathing Where Bathing
Facilities are Facilities are
to 200 lphd
Provided not Provided
litres/capita litres/capita
(1)
(2)
(3) (4)
SI
Type of Building
Consumption
No.
per Day, litres
(1)
(2)
(3)
i)
Factories where bath rooms are required
to be provided
45 per head
ii)
Factories where no bath rooms are
required to be provided
30 per head
iii)
Hospital (including laundry):
a) Number of beds not exceeding 100
340 per head
b) Number of beds exceeding 100
450 per head
iv)
Nurses' homes and medical quarters
135 per head
v)
Hostels
135 per head
vi)
Hotel (up to 4 Star)
180 per head
vii)
Hotel (5 Star and above)
320 per head
viii)
Offices
45 per head
ix)
Restaurants
70 per seat
x)
Cinemas, concert halls and theatres
15 per seat
xi)
Schools:
a) Day schools
45 per head
b) Boarding schools
135 per head
NOTE — For calculating water demand
for visitors a
c
onsumption of 15 litres per head, per day may be taken.
ii)
iii)
iv)
45
70
45
70
25
45
45
70
Intermediate stations
(excluding mail and
express stops)
Junction stations and
intermediate stations
where mail or express
stoppage is provided
Terminal stations
International and
domestic airports
NOTES
1 The number of persons shall be determined by average
number of passengers handled by the station daily; due
consideration may be given to the staff and vendors likely to
use facilities,
2 Consideration should be given for seasonal average peak
requirements.
4.1.4 Water Supply for Fire Fighting Purposes
4.1.4.1 The Authority shall make provision to meet
the water supply requirements for fire fighting in the
city/area, depending on the population density and
types of occupancy.
4.1.4.2 Provision shall be made by the owner of the
building for water supply requirements for fire fighting
purposes within the building, depending upon the
height and occupancy of the building, in conformity
with the requirements laid down in Part 4 Tire and
Life Safety'.
4.1.4.3 The requirements regarding water supply in
storage tanks, capacity of fire pumps, arrangements of
wet riser-cum-downcomer and wet riser installations
for buildings above 15 m in height, depending upon
the occupancy use, shall be in accordance with Part 4
Tire and Life Safety'.
4.1.5 Water Supply for Other Purposes
4.1.5.1 Water supply in many buildings is also
required for many other applications other than
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
19
domestic use, which must be identified in the initial
stages of planning so as to provide the requisite water
quantity, storage capacity and pressure as required for
each application. In such instances information about
the water use and the quality required may be obtained
from the users. Some typical uses other than domestic
use and fire fighting purposes are air conditioning and
air washing, swimming pools and water bodies and
gardening.
4.2 Water Sources and Quality
4.2.1 Sources of Water
The origin of all sources of water is rainfall. Water
can be collected as it falls as rain before it reaches the
ground; or as surface water when it flows over the
ground or is pooled in lakes or ponds; or as ground
water when it percolates into the ground and flows or
collects as ground water; or from the sea into which it
finally flows.
4.2.2 The quality of water to be used for drinking shall
be as per good practices [9-1(2)].
4.2.3 For purposes other than drinking, water if
supplied separately, shall be absolutely safe from
bacteriological contamination so as to ensure that there
is no danger to the health of the users due to such
contaminants.
4.2.4 Waste Water Reclamation
Treated sewage or other waste water of the community
may be utilized for non-domestic purposes such as
water for cooling, flushing, lawns, parks, fire fighting
and for certain industrial purposes after giving the
necessary treatment to suit the nature of the use. This
supply system shall be allowed in residences only if
proper provision is made to avoid any cross connection
of this treated waste water with domestic water supply
system.
4.2.5 Whenever a building is used after long intervals,
the water quality of the stored water must be checked
so as to ensure that the water is safe for use as per
water quality requirements specified in this Code.
4.3 Estimate of Demand Load
4.3.1 Estimates of total water supply requirements for
buildings shall be based on the occupant load consistent
with the provisions of 4.1.
4.3.1.1 For residential buildings, the requirements of
water shall be based on the actual number of occupants;
where this information is not available, the number of
occupants for each residential unit may be based on a
family of five. For assessing the population in other
occupants, reference may be made to Part 4 'Fire and
Life Safety'.
4.3.1.2 In making assessment of water supply
requirements of large complexes, the future occupant
load shall be kept in view. Use may be made of the
following methods for estimating future requirements:
a) demographic method of population projection,
b) arithmetic progression method,
c) geometrical progression method,
d) method of varying increment or incremental
increase,
e) logistic method,
f) graphical projection method, and
g) graphical comparison method.
4.4 Storage of Water
4.4.1 In a building, provision is required to be made
for storage of water for the following reasons:
a) to provide against interruptions of the supply
caused by repairs to mains, etc;
b) to reduce the maximum rate of demand on
the mains;
c) to tide over periods of intermittent supply; and
d) to maintain a storage for the fire fighting
requirement of the building (see Part 4 Tire
and Life Safety').
4.4.2 The water may be stored either in overhead tanks
(OHT) and/or underground tanks (UGT).
4.4.3 Materials Used
Reservoirs and tanks for the reception and storage of
water shall be constructed of reinforced concrete brick
masonry, ferrocement precast, mild steel, stainless steel
or plastic.
4.4.3.1 Tanks made of steel may be of welded, riveted
or pressed construction. The metal shall be galvanized
coated externally with a good quality anti-corrosive
weather-resisting paint. Lead-based paint shall not be
used in the tank. Lead-lined tanks shall not be used.
Rectangular pressed steel tanks shall conform to good
practice [9-1(3)].
4.4.4 Each tank shall be provided with the following:
a) Manholes — Adequate number of manholes
for access and repair. The manholes shall be
made of corrosion resistant material (for
example, cast iron, reinforced cement
concrete, steel fibre reinforced concrete,
galvanized steel, high density polyethylene,
fibre glass reinforced plastic or such other
materials acceptable to the Authority).
Manholes shall be provided with locking
arrangement to avoid misuse and tampering.
b) Catch Rings and Ladders — Tanks higher
20
NATIONAL BUILDING CODE OF INDIA
than 900 mm deep shall be provided with
corrosion resistant catch rings, steps or
ladders according to the depth to enable a
person to reach the bottom of the tank.
c) Overflow Pipe — Each tank shall be provided
with an overflow pipe terminating above the
ground/terrace level to act as a 'Warning Pipe'
to indicate overflow conditions. The size of
the overflow pipe shall be adequate to accept
the flow. Normally the overflow pipe size
shall be one size higher than the inlet pipe.
When the inlet pipe diameter is large, two or
more overflow pipes of equivalent cross-
section may be provided.
d) Vent Pipes — Tanks larger than 5 000 1
capacity shall be provided with vent pipes to
prevent development pressure in the tank
which might result in NO FLOW condition
or inward collapse of the tank.
e) Scour Pipe — Each tank shall be provided
with a scour pipe with an accessible valve for
emptying the tank.
f) Connection of Overflow and Scour Pipe —
Under no circumstances tank overflow and
scour pipe shall be connected to any drain,
gully trap or manhole to prevent back flow
and contamination of the water. All such
connections shall be discharged over a grating
with an air gap of 50 mm. All overflow and
vent pipes shall be provided with a mosquito
proof brass grating to prevent ingress of
mosquito, vermin and other insects.
g) The top slab of the tank must be suitable
sloped away from its .centre for proper
drainage of the rainwater.
h) Tanks on terraces and above ground shall be
supported by appropriate structural members
so as to transfer the load of the tank and the
water directly on the structural members of
the building.
4.4.5 Every storage tank shall be easily accessible and
placed in such a position as to enable thorough
inspection and cleaning to be carried out. If the
storage capacity required is more than 5 000 1, it is
advantageous to arrange it in a series of tanks so
interconnected that each tank can be isolated for
cleaning and inspection without interfering with the
supply of water. In large storage tanks, the outlet shall
be at the end opposite the inlet to avoid stagnation of
the water.
4.4.6 The outlet pipe shall be fixed 50 mm to 75 mm
above the bottom of the tank and fitted with a strainer,
preferably of brass.
4.4.7 In the case of underground storage tanks, the
design of the tank shall be such as to provide for the
draining of the tank when necessary and water shall
not be allowed to collect around the tank. The tank
shall be perfectly water-proof and shall be provided
with a cement concrete cover, having a manhole
opening, with a properly fitting hinged cast iron cover
on a leak-proof cast iron frame.
The underground tanks should not be located in low
lying areas or near any public or private sewer, septic
tank, leaching pool or soakage pit to prevent any
contamination. The overflow of the tank should be well
above (preferably 600 mm) the external surface level
and terminate as a warning pipe with a mosquito proof
grating. Care must be taken to prevent backflow of
local surface water into the tank in case of local
flooding. Otherwise the overflow must be terminated
in a more safer manner as per the site conditions. For
tanks with atleast one side exposed to a basement, it is
safer to discharge the overflow into the basement level.
The tank top slab shall also be designed to carry the
load due to fire tender movement where anticipated as
in the case of an extended basement.
There should be no common wall between the tanks
storing safe water and tanks storing water from unsafe
sources.
4.4.8 In case of overhead tanks, bottom of the tanks
shall be placed clear off the terrace slab such that the
elevation difference between the outlet pipe of the tank
and the highest fixture at the top floor of the building
is minimum 2 m, which shall also prevent leakage into
the structural slab. In tall buildings, the top of the tank
shall be provided with the safe ladder or staircase. The
top slab shall be provided with railing or a parapet wall.
4.4.9 For jointing steel pipe to a storage tank, the end
of the pipe shall be screwed, passed through a hole in
the tank and secured by backnuts, both inside and
outside. The pipe end shall be flush with the face of
the inside backnut. For jointing copper pipe to steel or
copper tank, a connector of non-ferrous material shall
be used. The connector shall have a shoulder to bear
on the outside of the tank and shall be secured by a
backnut inside.
4.4.10 The quantity of water to be stored shall be
calculated taking into account the following factors:
a) hours of supply at sufficiently high pressure
to fill up the overhead storage tanks;
b) frequency of replenishment of overhead
tanks, during the 24 h;
c) rate and regularity of supply; and
d) consequences of exhausting storage
particularly in case of public buildings like
hospitals.
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
21
If the water supply is intermittent and the hours of
supply are irregular, it is desirable to have a minimum
storage of half a day's supply for overhead tanks. For
additional requirement of water storage for fire fighting
purposes, reference may be made to Part 4 Tire and
Life Safety'.
NOTE — General guidelines for calculation of capacity of these
storage tanks are as follows:
a) In case only OHT is provided, it may be taken as 33.3
to 50 percent of one day's requirement;
b) In case only UGT is provided, it may be taken as 50 to
150 percent of one day's requirement; and
c) In case combined storage is provided, it may be taken
as 66.6 percent UGT and 33.4 percent OHT of one day's
requirement.
4.4.11 When only one communication pipe is
provided for water supply to a building, it is not
necessary to have separate storage for flushing and
sanitary purposes for health reasons. In such cases
when only one storage tank has been provided, tapping
of water may be done at two different levels (the lower
tapping for flushing) so that a part of the water will be
exclusively available for flushing purposes.
4.5 Materials, Fittings and Appliances
4.5.1 Standards for Materials, Fittings and Appliances
All materials, water fittings and appliances shall
conform to Part 5 'Building Materials'.
4.5.2 Materials for Pipes
Pipes may be of any of the following materials:
a) cast iron, vertically cast or centrifugally
(spun) cast,
b) steel (internally lined or coated with bitumen
or a bituminous composition, and out-coated
with cement concrete or mortar, where
necessary),
c) reinforced concrete,
d) prestressed concrete,
e) galvanized mild steel tubes,
f) copper,
g) brass,
h) wrought iron,
j) asbestos cement,
k) polyethylene,
m) unplasticized PVC,
n) chlorinated PVC, or
p) stainless steel.
4.5.2.1 The material chosen shall be resistant to
corrosion, both inside and outside or shall be suitably
protected against corrosion.
4.5.2.2 Polyethylene and unplasticized PVC pipes
shall not be installed near hot water pipes or near any
other heat sources. For temperature limitations in the
use of polyethylene and unplasticized PVC pipes to
convey water, reference may be made to good practice
[9-1(4)].
4.6 Design of Distribution Systems
4.6.1 General
All buildings shall conform to the general requirements
given in 3.1.
4.6.2 Rate of Flow
One of the important items that needs to be determined
before the sizes of pipes and fittings for any part of the
water piping system may be decided upon, is the rate
of flow in the service pipe which, in turn depends upon
the number of hours for which the supply is available
at sufficiently high pressure. If the number of hours
for which the supply is available is less, there will be
large number of fittings in use simultaneously and the
rate of flow will be correspondingly large.
The data required for determining the size of the
communication and service pipes are:
a) the maximum rate of discharge required;
b) the length of the pipe; and
c) the head loss by friction in pipes, fittings and
meters.
4.6.3 Discharge Computation
4.6.3.1 Design of consumer's pipes based on fixture
units
The design of the consumers' pipes or the supply pipe
to the fixtures is based on:
a) the number and kind of fixtures installed;
b) the fixture unit flow rate; and
c) the probable simultaneous use of these
fixtures.
The rates at which water is desirably drawn into
different types of fixtures are known. These rates
become whole numbers of small size when they are
expressed in fixture unit.
The fixture units for different sanitary appliances or
groups of appliances are given in Table 3 and Table 4.
4.6.3.2 Probable simultaneous demand
The possibility that all water supply taps in any system
in domestic and commercial use will draw water at the
same time are extremely remote. Designing the water
mains for the gross flow will result in bigger and
uneconomical pipe mains and is not necessary. A
probability study made by Hunter suggests the
relationship shown in Fig. 5 and Table 5. In the absence
22
NATIONAL BUILDING CODE OF INDIA
Table 3 Fixture Unit for Different Types of
Fixtures with Inlet Pipe Diameter
(Clause 4.63 A)
Table 4 Fixture Unit for Different Types of
Fixtures Based on Pipe or Trap Diameter
(Clause 4.6.3.1)
SI
No.
(1)
Type of Fixture
(2)
Fixture
UnitFU
as Load
Factor
(3)
Minimum
Normal Size
of Fixture
Branch, mm
(4)
i) Ablution tap 1
ii) Bath tub supply by spout 3
Shower over tub does not add to the
load
iii) Shower stall domestic 2
iv) Shower in groups per head 3
v) Wash basin domestic use 1
vi ) Wash basin public use 2
vii) Wash basin surgical 2
viii) Scrub station in hospitals per outlet 3
ix) Drinking water fountain/water cooler 0.5
x) Water-closet with cistern (single/ 1
double flush)
xi) Water-closet with flush or magic 8
eye operated valve
xii) Urinals with auto flushing cisterns 4
xiii) Urinals with flush or magic eye 2
operated valve
xiv) Kitchen sink (domestic use) 2
xv) Washing machine 3
30
15
15
15
15
15
15
15
15
15
15
25/32
15/20
15/20
15/20
15/20
SI
Drain or Trap Outlet
Fixture Unit
No.
Diameter
mm
FU
(1)
(2)
(3)
i)
32 or smaller
1
ii)
40
2
iii)
50
3
iv)
65
4
v)
75
5
vi)
100
6
NOTE — Before using the above figures check the
actual flow from the outlets of special equipment, for
example, small period high discharges, for example, from
washing machines, boiler blow downs, filter backwash and
water tank emptying operations.
25
20
z
Q
Z
<
W 15
9 10
CD
8 5
a.
-
V
VIT
HF
: LL
ISh
IV)
\L\
/El
W
n>
IFI
.IK
3H
TA
NK
S
20 60 100 140 180 220 300 500 700 900
TOTAL FIXTURE UNITS
5A GRAPH FOR PROBABLE DEMAND ON PIPE
LINES UPTO DEMAND OF 900 FU
70
60
<
5
50
in
Q
40
LU
_ 1
30
m
<
20
CO
O
10
Q_
I I
WITH FLUSH VALVES
OR TANKS
1000
1500
2000
2500
3000
TOTAL FIXTURE UNITS
5B GRAPH FOR PROBABLE DEMAND 6VER 900 FU
Fig. 5 Graph for Probable Demand
PART 9 PLUMBING SERVICES — SECTION I WATER SUPPLY, DRAINAGE AND SANITATION
23
Table 5 Probable Simultaneous Demand
(Clause 4.6.3.2)
No. of
System with Flush Tanks Demand
System
with Flush Valves Demand
Fixture Units
(Based on
Fixture Units)
(After Hunter)
-*^
__ t ^ mm ^
Unit Rate of Flow"
Flow in Litre per Minute
Unit Rate of Flow !)
— **
Flow in Litre per Minute
(1)
(2)
(3)
(4)
(5)
20
2.0
56.6
4.7
133.1
40
3.3
93.4
6.3
178.4
60
4.3
121.8
7.4
209,5
80
5.1
144.4
8.3
235.0
100
5.7
161.4
9.1
257.7
120
6.4
181.2
9.8
277.5
140
7 J
201.0
10.4
294.5
160
7.6
215.2
11.0
311.5
180
8.2
232.2
11.6
328.5
200
8.6
243.5
12.3
348.3
220
9.2
260.5
12.7
359.6
240
9.6
271.8
13.1
370.9
300
11.4
322.8
14.7
416.2
400
14.0
396.4
17,0
481.4
500
16.7
472.9
19.0
538.0
600
19.4
549.3
21.1
597.5
700
21.4
606.0
23.0
651.3
800
24.1
682.4
24.5
693.7
900
26.1
739.0
26.1
739.0
1 000
28.1
795.7
28.1
795.7
1500
36.1
1 022.2
36.1
1 022.2
2 000
43.9
! 243.1
43.9
1 243.1
2 500
51.1
1 446.9
51.1
1446.9
3 000
57.8
= Effective fixture units.
1 636.7
57.8
1 636.7
" Unit rate of flow =
of similar studies in India, the curves based on Hunter's
study may be followed. In making use of these curves,
special allowances are made as follows:
a) Demands for service sinks are ignored in
caicuiating the total fixture demand.
b) Demands of supply outlets such as hose
connections and air conditioners through
which water flows more or less continuously
over a considerable length of time must be
added to the probable flow rather than the
fixture demand,
c) Fixtures supplied with both hot and cold water
exert reduced demands upon main hot water
and cold water branches (not fixture branches).
4.6.4 Pipe Size Computation
Commercially available standard sizes of pipes are only
to be used against the sizes arrived at by actual design.
Therefore, several empirical formulae are used, even
though they give less accurate results. The Hazen and
William's formula and the charts based on the same
may be used without any risk of inaccuracy in view of
the fact that the pipes normally to be used for water
supply are of smaller sizes. Nomogram of Hazen and
William's equation has been provided in Annex F.
4.7 Distribution Systems in Multi-Storeyed
Buildings
4.7.1 There are four basic methods of distribution of
water to a multi-storeyed buildings.
a) Direct supply from mains to ablutionary taps
and kitchen with WCs and urinals supplied
by overhead tanks.
b) Direct Pumping Systems
c) Hydro-Pneumatic Systems
d) Overhead Tanks Distribution
4.7.2 Direct Supply System
This system is adopted when adequate pressure is
available round the clock at the topmost floor. With
limited pressure available in most city mains, water
from direct supply is normally not available above two
or three floors. For details of this system, reference
may be made to good practice [9-1(5)] may be referred.
4.7.3 Direct Pumping
4.7.3.1 Water is pumped directly into the distribution
system without the aid of any overhead tank, except
for flushing purposes. The pumps are controlled by a
pressure switch installed on the line. Normally a jockey
24
NATIONAL BUILDING CODE OF INDIA
pump of smaller capacity installed which meets the
demand of water during low consumption and the main
pump starts when the demand is greater. The start and
stop operations are accomplished by a set if pressure
switches are installed directly on the line. In some
installation, a timer switch is installed to restrict the
operating cycle of the pump.
centrally air conditioned buildings for which a constant
make up supply for air conditioning cooling towers is
required.
4.7.3.3 The s v stem de n ends on a constant and reliable
sijmnlv of nower. Anv failure in the power system
would result in a breakdown in the water supply
svstem.
4.7.3.2 Direct pumping systems are suitable for 4.7.3.4 The system eliminates the requirements of
uUiiuiugs Wiiere a certain amount Oi constant use Gi
w aici is a.iw ay a uLLumug. ± utat LFuiivinigd ait a.n
overhead tanks for dunicstiu purposes (exceyi iur
iiusiimg) and requires minimum space (see r'ig. u;.
TOWER -
-O H TANK
riippi Y MAIN-
\
\
\
\
Tir^
TERRACE
WC
KITCHEN/BATH
FLOOR 6
WC
KITCHEN/BATH
FLOOR 5
KITCHEN/BATH
WC
FLOOR 4
I WALL
I ■""■■"
X
ROAD |j
-rT77TT77TT7Y
KITCHEN/BATH
WC
FLOOR 3
KITCHEN/BATH
WC
FLOOR 2
WC
— KITCHEN/BATH
FLOOR 1
'//////SfffSSSSSSSSfSfrrs ' ' ' ' *
\ iMncpGRQUND
TANK
-CITY WATER
MAiNS
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
zr>
4.7.4 Hydro- Pneumatic Systems
4.7.4.1 Hydro-pneumatic system is a variation of
direct pumping system. An air-tight pressure vessel is
installed on the line to regulate the operation of the
pumps. The vessel capacity shall be based on the cut-
in and cut-out pressure of the pumping system
depending upon allowable start/stops of the pumping
system. As pumps operate, the incoming water is
the vessel, compresses the air on top. When a
predetermined pressure is reached in the vessel, a
pressure switch installed on the vessel switches off the
pumps. As water is drawn into the system, pressure
falls into the vessel starting the pump ar preset pressure.
The air in the pressure tank slowly reduces the volume
due to dissolution in water and leakages from pipe
lines. An air compressor is also necessary to feed air
into the vessel so as to maintain the required air-water
ratio. The system shall have reliable power supply to
avoid breakdown in the water supply.
4.7.4.2 There is an alternate option of providing
variable speed drive pumping system where a pump
with a large variation in its pressure-discharge and
speed of the pump is efficiently used to deliver water
at rates of flow as required by the system by changing
its speed by a varying its with the assistance of an
electronic device which will reduce the rate of flow
from speed of the motor from 960 rpm to 3 000 rpm.
With this arrangement the same pump is able to deliver
water as required at different times of the day. The
system consumes energy in proportion to the work
done and save considerable amount of power
as compared to the fixed speed pumps used
conventionally.
4.7.4.3 Hydro-pneumatic system generally eliminates
the need for an over head tank and may supply water
at a much higher pressure than available from overhead
tanks particularly on the upper floors, resulting in even
distribution of water at all floors (see Fig. 7).
SUPPLY
MAIN -
PRESSURE
TANK-
COMPRESSED
AiR LiNE-
AIR
COMPRESSOR
TERRACE
FIXTURE f f
FIXTURE
l_i
FIXTURE
JJL
FIXTURE
-Li
FIXTURE
i_L
FIXTURE
J_i
FIXTURE
iJL
FIXTURE
JUL
AiR
CHAMBER
FLOOR 8
FLOOR 7
FLOOR 6
FLOOR 5
FLOOR 4
FLOOR 3
FLOOR 2
/ / / / / / ,> / / / J / J / / / / / , J / / /
FLOOR 1
-CITY WATER
MAINS
UNDERGROUND
TANK
Fig. 7 Hydro-Pneumatic System
26
NATIONAL BUILDING CODE OF INDIA
4.7.5 Overhead Tank Distribution
4.7.5.1 This is the most common of the distribution
systems adopted by various type of buildings.
4.7.5.2 The system comprises pumping water to one
or more overhead tanks placed at the top most location
of the hydraulic zone.
4.7.5.3 Water collected in the overhead tank is
distributed to the various parts of the building by a set
of pipes located generally on the terrace.
4.7.5.4 Distribution is accomplished by providing
down takes to various fixtures {see Fig. 8).
4.8 General Requirements for Pipe Work
4.8.1 Mains
The following principles shall apply for the mains:
a) Service mains shall he of adequate size to give
the required rate of flow.
b) The mains shall be divided into sections by
DOMESTIC
SUPPLY TANK
DOMESTIC
MAINS
SUPPLY
MAIN-
DOMESTIC
SUPPLY TANK -
KITCHEN/
BATH "
KITCHEN/
BATH -
KITCHEN/
BATH "
KITCHEN/
BATH ™
KITCHEN/
BATH "
KITCHEN/
BATH "
TERRACE
-FLUSHING
WC MAINS
WC
WC
WC
WC
WC
TOP FLOOR
FLOOR 6
FLOOR 5
FLOOR 4
FLOOR 3
FLOOR 2
WC
////////////////////// FLOOR 1
-CITY WATER
MAINS
UNDERGROUND
TANK
Fig. 8 Overhead Tank Distribution
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
27
the provisions of sluice valves and other
valves so that water may be shut off for
repairs.
c) To avoid dead ends, the mains shall be
arranged in a grid formation or in a network.
d) Where dead ends are unavoidable, a hydrant
shall be provided to act as a wash-out.
e) The wash-out valve shall not discharge
directly into a drain or sewer, or into a
manhole or chamber directly connected to it;
an effectively trapped chamber shall be
interposed, into which the wash-out shall
discharge.
f) Air valves shall be provided at all
summits, and wash-out at low points between
summits.
g) Mains need not be laid at unvarying gradients,
but may follow the general contour of
the ground. They shall, however, fall
continuously towards the wash-out and rise
towards the air valves. The gradient shall be
such that there shall always be a positive
pressure at every point under working
conditions.
h) The cover for the mains shall be at least
900 mm under roadways and 750 mm in the
case of footpaths. This cover shall be
measured from the top of the pipe to the
surface of the ground.
j) The mains shall be located sufficiently away
from other service linest like electric and
telegraph cables to ensure safety and where
the mains cannot be located away from such
lines, suitable protective measures shall be
accorded to the mains.
4.8.2 Communication Pipes
a) Every premises that is supplied with water
by the Authority shall have its own separate
communication pipe. In the case of a group
or block of premises belonging to the same
owner the same communication pipe may
supply water to more than one premises with
the prior permission of the Authority.
b) The communication pipe between the
water main and the stop-cock at the
boundary of the premises shall be laid by the
Authority.
c) Connections up to 50 mm diameter may be
made on the water main by means of screwed
ferrules, provided the size of the connections
does not exceed one-third the size of the water
main. In all other cases, the connection shall
be made by a T-branch off the water main.
d) As far as practicable, the communication pipe
and the underground service pipe shall be
laid at right angles to the main and in
approximately straight lines to facilitate
location for repairs. It is also recommended
that the communication pipe be laid in a
pipe in pipe sleeve of larger dia. Made of
non-corrosive material to protect the
communication pipe.
e) Every communication pipe shall have a stop-
cock and meter inserted in it. The waterway
of each such fitting shall not be less than the
internal sectional area of the communication
pipe and the fittings shall be located within
the premises at a conspicuous place accessible
to the Authority which shall have exclusive
control over it.
4.8.3 Consumer Pipes
a) No consumer pipe shall be laid in the premises
to connect the communication pipe without
the approval of the Authority.
b) The consumer pipe within the premises shall
be laid underground with a suitable cover to
safeguard against damage from traffic and
extremes of weather.
c) To control the branch pipe to each separately
occupied part of a building supplied by a
common service pipe, a stop tap shall be
fixed to minimize the interruption of the
supply during repairs. All such stop valves
shall be fixed in accessible positions and
properly protected. To supply water for
drinking or for culinary purposes, direct taps
shall be provided on the branch pipes
connected directly to the consumer pipe.
In the case of multi-storeyed buildings,
downtake taps shall be supplied from
overhead tanks.
d) Pumps shall not be allowed on the service
pipe, as they cause a drop in pressure on the
suction side, thereby affecting the supply to
the adjoining properties. In cases where
pumping is required, a properly protected
storage tank of adequate capacity shall be
provided to feed the pump.
e) No direct boosting (by booster pumps)
shall be allowed from the service pipes
(communication and consumer pipes).
f) Consumer pipes shall be so designed and
constructed as to avoid air-locks. Draining
taps shall be provided at the lowest points
from which the piping shall rise continuously
to draw-off taps.
28
NATIONAL BUILDING CODE OF INDIA
g) Consumer pipes shall be so designed as to
reduce the production and transmission of
noise as much as possible.
h) Consumer pipes in roof spaces and
unventilated air spaces under floors or
in basements shall be protected against
corrosion.
j) Consumer pipes shall be so located that they
are not unduly exposed to accidental damage
and shall be fixed in such positions as to
facilitate cleaning and avoid accumulations
of dirt.
All consumer pipes shall be so laid as to permit
expansion and contraction or other movements.
4.8.4 Prohibited Connections
a) A service pipe shall not be connected into any
distribution pipe; such connection may permit
the backflow of water from a cistern into the
service pipe, in certain circumstances, with
consequent danger of contamination and
depletion of storage capacity. It might also
result in pipes and fittings being subjected to
a pressure higher than that for which they are
designed, and in flooding from overflowing
cisterns.
b) No pipe for conveyance or in connection with
water supplied by the Authority shall
communicate with any other receptacle used
or capable of being used for conveyance other
than water supplied by the Authority.
c) Where storage tanks are provided, no person
shall connect or be permitted to connect any
service pipe with any distributing pipe.
d) No service or supply pipe shall be connected
directly to any water-closet or a urinal.
All such supplies shall be from flushing
cisterns which shall be supplied from storage
tank.
e) No service or supply pipe shall be connected
directly to any hot water system or to any
other apparatus used for heating other than
through a feed cistern thereof.
4.9 Jointing of Pipes
4.9.1 Cast Iron Pipes
Jointing may be done by any of the following
methods:
a) spigot and socket joints, or
b) flanged joints in accordance with good
practice [9-1(6)]. The lead shall conform to
the accepted standards [9-1(7)].
4.9.2 Steel Pipes
Plain-ended steel pipes may be jointed by welding.
Electrically welded steel pipes shall be jointed in
accordance with good practice [9-1(8)].
4.9.3 Wrought Iron and Steel Screwed Pipes
Screwed wrought iron or steel piping may be jointed
with screwed and socketed joints. Care shall be taken
to remove any burr from the end of the pipes after
screwing. A jointing compound approved by the
Authority and containing no red lead composition shall
be used. Screwed wrought iron or steel piping may
also be jointed with screwed flanges.
4.9.4 Asbestos Cement Pipes
Asbestos cement pipes may be jointed in accordance
with good practice [9-1(9)].
4.9.5 Copper Pipes
Copper pipes shall be jointed by internal solder ring
joint, end-brazing joint or by use of compression fitting.
The flux used shall be non-toxic and the solder used
shall be lead free. The use of dezincification fittings
shall be made in case of jointing of copper pipe and
steel pipe.
4.9.6 Concrete Pipes
Concrete pipes shall be jointed in accordance with good
practice [9-1(10)].
4.9.7 Polyethylene and Unplasticized PVC Pipes
Polyethylene and unplasticized PVC pipes shall be
jointed in accordance with good practice [9-1(11)].
4.10 Backflow Prevention
4.10.1 The installation shall be such that water
delivered is not liable to become contaminated or that
contamination of the public water supply does not
occur.
4.10.2 The various types of piping and mechanical
devices acceptable for backflow protection are:
a) Barometric loop,
b) Air gap,
c) Atmosphere vacuum breaker,
d) Pressure vacuum breaker,
e) Double check valve, and
f) Reduced pressure backflow device.
4.10.3 The installation shall not adversely affect
drinking water:
a) by materials in contact with the water being
unsuitable for the purpose;
b) as a result of backflow of water from water
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
29
fittings, or water using appliances into
pipework connected to mains or to other
fittings and appliances;
c) by cross-connection between pipes conveying
water supplied by the water undertaker with
pipes conveying water from some other
source; and
d) by stagnation, particularly at high temperatures.
4.10.4 No pump or similar apparatus, the purpose of
which is to increase the pressure in or rate of flow from
a supply pipe or any fitting or appliance connected to
a supply pipe, shall be connected unless the prior
written permission of the water supplier has been
obtained in each instance.
The use of such a pump or similar apparatus is likely
to lead to pressure reduction in the upstream pipe work
which, if significant, increase the risk of backflow from
other fittings.
4.10.5 The water shall not come in contact with
unsuitable materials of construction.
4.10.6 No pipe or fitting shall be laid in, on or through
land fill, refuse, an ashpit, sewer, drain, cesspool or
refuse chute, or any manhole connected with* them.
4.10.7 No pipe susceptible to deterioration by contact
with any substance shall be laid or installed in a place
where such deterioration is likely to occur. No pipe
that is permeable to any contaminant shall be laid or
installed in any position where permeation is likely to
occur.
4.10.8 If a liquid (other than water) is used in any type
of heating primary circuit, which transfers heat to water
for domestic use, the liquid shall be non-toxic and non-
corrosive.
4.10.9 A backflow prevention device shall be arranged
or connected at or as near as practicable to each point
of delivery and use of water. Appliances with built-in
backflow prevention shall be capable of passing the
test. All backflow prevention devices shall be installed
so that they are accessible for examination, repair or
replacement. Such devices shall be capable of being
tested periodically by the Authority to ensure that the
device is functioning efficiently and no backflow is
occurring at any time.
4.11 Conveyance and Distribution of Water Within
the Premises
4.11.1 Basic Principles
Wholesome water supply provided for drinking and
culinary purposes shall not be liable to contamination
from any less satisfactory water. There shall, therefore,
be no cross-connection whatsoever between the
distribution system for wholesome water and any pipe
or fitting containing unwholesome water, or water
liable to contamination, or of uncertain quality, or water
which has been used for any other purpose. The
provision of reflux or non-return valves or closed and
sealed stop valves shall not be construed as a
permissible substitute for complete absence of cross-
connection.
4.11.2 The design of the pipe work shall be such that
there is no possibility of backflow towards the source
of supply from any cistern or appliance, whether by
siphonage or otherwise. Reflux non-return valves shall
not be relied upon to prevent such backflow.
4.11.3 Where a supply of less satisfactory water than
wholesome water becomes inevitable as an alternative
or is required to be mixed with the latter, it shall be
delivered only into a cistern and by a pipe or fitting
discharging into the air gap at a height above the top
edge of the cistern equal to twice its nominal bore and
in no case less than 150 mm. It is necessary to maintain
a definite air gap in all appliances or taps used in water-
closets.
4.11.4 All pipe work shall be so designed, laid or fixed
and maintained as to remain completely water-tight,
thereby avoiding wastage, damage to property and the
risk of contamination.
4.11.5 No water supply line shall be laid or fixed so
as to pass into or through any sewer, scour outlet or
drain or any manhole connected therewith nor through
any ash pit or manure pit or any material of such nature
that is likely to cause undue deterioration of the pipe,
except where it is unavoidable.
4.11.5.1 Where the laying of any pipe through
corrosive soil or previous material is unavoidable, the
piping shall be properly protected from contact with
such soil or material by being carried through an
exterior cast iron tube or by some other suitable means
as approved by the Authority. Any existing piping or
fitting laid or fixed, which does not comply with the
above requirements, shall be removed immediately by
the consumer and relaid by him in conformity with
the above requirements and to the satisfaction of the
Authority.
4.11.5.2 Where lines have to be laid in close proximity
to electric cables or in corrosive soils, adequate
precautions/protection should be taken to avoid
corrosion.
4.11.6 Underground piping shall be laid at such a
depth that it is unlikely to be damaged by frost or traffic
loads and vibrations. It shall not be laid in ground liable
to subsidence, but where such ground cannot be
avoided, special precautions shall be taken to avoid
30
NATIONAL BUILDING CODE OF INDIA
damage to the piping. Where piping has to be laid
across recently disturbed ground, the ground shall be
thoroughly consolidated so as to provide a continuous
and even support.
4.11.7 In designing and planning the layout of the pipe
work, due attention shall be given to the maximum
rate of discharge required, economy in labour and
materials, protection against damage and corrosion,
water hammer, protection from frost* if required, and
to avoidance of airlocks, noise transmission and
unslightly arrangement.
4.11.8 To reduce frictional losses, piping shall be as
smooth as possible inside. Methods of jointing shall
be such as to avoid internal roughness and projection
at the joints, whether of the jointing materials or
otherwise.
4.11.9 Change in diameter and in direction shall
preferably be gradual rather than abrupt to avoid undue
loss of head. No bend or curve in piping shall be made
which is likely to materially diminish or alter the cross-
section.
4.11.10 No boiler for generating steam or closed
boilers of any description or any machinery shall be
supplied direct from a service or supply pipe. Every
such boiler or machinery shall be supplied from a feed
cistern.
4.12 Laying of Mains and Pipes on Site
4.12.1 The mains and pipes on site shall be laid in
accordance with good practice [9-1(12)].
4.12.2 Excavation and Refilling
The bottoms of the trench excavations shall be so
prepared that the barrels of the pipes, when laid, are
well bedded for their whole length on a firm surface
and are true to line and gradient. In the refilling of
trenches, the pipes shall be surrounded with fine
selected material, well rammed so as to resist
subsequent movement of the pipes. No stones shall be
in contact with the pipes; when resting on rock, the
pipes shall be bedded on fine-selected material or
(especially where there is a steep gradient) on a layer
of concrete.
4.12.2.1 The pipes shall be carefully cleared of all
foreign matter before being laid.
4.12.3 Laying Underground Mains
Where there is a gradient, pipe laying shall proceed in
'uphill' direction to facilitate joint making.
4.12.3.1 Anchor blocks shall be provided to withstand
the hydraulic thrust.
4.12.4 Iron surface boxes shall be provided to give
access to valves and hydrants and shall be supported
on concrete or brickwork which shall not be allowed
to rest on pipes.
4.12.5 Laying Service Pipes
4.12.5.1 Service pipes shall be connected to the mains
by means of right-hand screw down ferrule or
T-branches. The ferrules shall conform to accepted
standards [9-1(13)].
4.12.5.2 Precaution against contamination of the
mains shall be taken when making a connection and,
where risk exists, the main shall be subsequently
disinfected. The underground water service pipe and
the building sewer or drain shall be kept at a sufficient
distance apart so as to prevent contamination of water.
Water service pipes or any underground water pipes
shall not be run or laid in the same trench as the
drainage pipe. Where this is unavoidable, the following
conditions shall be fulfilled:
a) The bottom of the water service pipe, at all
points, shall be at least 300 mm above the top
of the sewer line at its highest point.
b) The water service pipe shall be placed on a
solid shelf excavated on one side of the
common trench.
c) The number of joints in the service pipe shall
be kept to a minimum.
d) The materials and joints of sewer and water
service pipe shall be installed in such a manner
and shall possess such necessary strength and
durability as to prevent the escape of solids,
liquids and gases therefrom under all known
adverse conditions, such as corrosion strains
due to temperature changes, settlement,
vibrations and superimposed loads.
4.12.5.3 The service pipe shall pass into or beneath
the buildings at a depth of not less than 750 mm below
the outside ground level and, at its point of entry
through the structure, it shall be accommodated in a
sleeve which shall have previously been solidly built
into the wall of the structure. The space between the
pipe and the sleeve shall be filled with bituminous or
other suitable material for a minimum length of
150 mm at both ends.
4.12.6 Pipes Laid Through Ducts, Chases, Notches
or Holes
Ducts or chases in walls for piping shall be provided
during the building of the walls. If they are cut into
existing walls, they shall be finished sufficiently
smooth and large enough for fixing the piping.
4.12.6.1 Piping laid in notches or holes shall not be
subjected to external pressure.
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
31
4.12.7 Lagging of Pines
VVnerc lagged piping outside buildings is attached to
vvlui^, ti ^!ian i/t diuid_y tuvci cu an iuuiiu w uii wdici-
r-irvA/"\i QnH fnv incnlofinfT tnotAnil on/] chotl ti/-^f Kti i * ■
J71WV* U1IU LIIV. llMUiUllll^ llllUVllUL ClxAV4. JllUIl uui VJ\^ in
,',irf*.-t rt\r\U\^t \x/ifh thf 1 u/nll Whprp if nscepe thrrutah n
wnll. the lafTainp shnll he confirmed thronf-honf the
„ — ^^ — — _- —
thickness of the wall.
4.13 Hot Water Supply Installations
4.13.1 Design Consideration
In electric water heating practice for domestic
purposes, the accepted method is to use storage heaters
in which water is steadily heated up to a predetermined
temperature and stored until required for use. The
heating by electricity of a Large quantity of water, such
as water required for a hot bath, within the time
normally taken to run the water into the bath, requires
a neater oi too hign a rating to ue practicauie in nomiai
4.13.1.2 In modern hotels and apartment blocks and
service apartments, centralized storage and distribution
systems are adopted, where other energy sources such
as oil, gas, solar panels, etc, may be used for the
generation of hot water as these options prove more
~~,™~™:.™i „^a ,w.« — „:~„+ :« u«„*-:«~ i~ — i..«,„„
ctunuuiiLdi anu. ^uuvciiiciiL in neaiing ltuge vuiuiue&
• T
4.13.1.3 When water supplied to the buildings contain
dissolved salts resulting in hardness of water, measures
such as installation of water softening plants etc shall
maximum short time demand of the domestic premises.
Depending on local conditions this shall be 50 1 to 75 1
at 60°C in a dwelling with a bath tub and 25 1 at 60°C
for a shower or a tap (for bucket supply). The capacity
of the storage vessel shall not be less than 20 percent
in excess of the required maximum short time demand.
In larger houses where a single hot water heater is
intended to supply hot water to more than one bathroom
or kitchen or both, the maximum short time demand
shall be estimated and the capacity decided
accordingly. Small electric or gas storage heaters of
1 5 1 to 25 1 capacity may be used to supply one or two
jj^iiil;> \jl uidw \jll u-cpcnuing ^n liic uac; \jl hkjl watt/i,
r*nlH \\tz\(*t ic m.Yi^H \17.th it sitv* cri\7f*n in T^hl^ f\
W^AV* TT UIV1 lU 1111/LVU »T 1L11 it Ul V t- X * V X-A. Ill J. UUIW *^ »
Table 6 Volume of Hot Water Required for a
Bath when Cold Water is Mixed with It
(Clause 4.13.3)
Storage temperature, "C
75
70
65
60
55
50
rerceiuage or noi waier
reau.red
DL
DD
ou
00
/j
OZ.Z)
Quantity of hot water in 59
litres required for a
115 litre bath
63
69 76 84 95
NOTE — Hot bath temperature at 41°C and cold water at
about 5 to 5.5°C.
4.1.3.4 Kate oj t tow
With storage type installation, the recommended
minimum rates of flow for different types of fixtures
are given in Table 7.
iiiMaiiaiiv;ii:>.
4.13.2 Storage Temperature
4.13.2.1 The design of hot water supply system and
its appliances shall be based on the temperatures at
which water is normally required for the various uses,
namelv:
d^ c r a« mn fnr.i«P!it41°r
{Clause 4.1^.4;
Sink
KJK/ \_-
Hot bath
43 C C a;
Warm bath
37°C
Tenid bath
29.5°C
4. i^.z.z in oraer to minimize tne aanger or seaming,
precipitation of scale from hard water, standing heat
losses, fjsk Oi steam iomiation and the possibility oi
finichpc a et-r.rarr£» t£»rr»rwar<ai-i ir/* r^f f\(\ f^ it' rA^nmmAnHAH
If storage ca n acit v is limited, a higher tem n erature u n
to 65 °C may be adopted when soft water is used,
4.13.3 Storage Capacity
The size of the storage vessel is governed by the
SI No.
Fixtures
Rate of Flow litres/min
(1)
(2)
(3)
i.
Bath tub
22.5
ii)
Kitchen sink
18
ni)
Wash basin
7
7
4.13.5 Design of Storage Vessel
oiorage lanKS snaii De ooiong or cyiinuricai in snape
— a „u~n u~ : — «-„ii„j c ui :±u *u^ i „;a~
anu Miau uc insLinicu, piciciauiy wilii liic lung aiuc
'1 Q\/f rin rr' r*-f rtr\t r\r cr\]r\ winter "Tti^ rctti^i ^if ti^irrti^ t/^i
lUJ VUIit V/l 11VI VI W1U »I UIV1 . X 11V 1U11V V/X IlVltlll wv
width or diameter shall not be less than 2;1. An inlet
baffle should preferably be fitted near the cold inflow
pipe in order to spread the incoming cold water.
4.13.6 Materials for Storage Vessel and Pipes
4.13.6.1 Under no circumstances shall ungalvanized
(black) mild steel pipes and fittings, such as sockets,
bushes, etc, be used in any part of a hot water
32
NATIONAL BUILDING CODE OF INDIA
installation, including the cold feed pipe and the vent
pipe. Materials resistant to the chemical action of water
supplied shall be used in construction of vessels and
pipes. Each installation shall be restricted to one type
of metal only, such as all copper or all galvanized mild
steel. When water supplied is known to have
appreciable salt content, galvanized iron vessels and
pipes shall not be used. However, it is advisable to
avoid use of lead pipes in making connection to wash
basins. Where required it is also advisable to use vessels
lined internally with glass, stainless steel, etc.
4.13.6.2 In general tinned copper and other metals
such as monel metal etc are suitable for most types of
water. The suitability of galvanized mild steel for
storage tanks depends upon the pH value of the water
and the extent of its temporary hardness. For values of
pH 7.2 or less, galvanized mild steel should not be
used. For values of pH 7.3 and above, galvanized mild
steel may be used provided the corresponding
temporary hardness is not lower than those given
below:
pH Value
7.3
7.4
7.5
7.6
7.7
7.8
7.9-8.5
Minimum Temporary
Hardness Required
(mg/1)
210
150
140
110
90
80
70
4.13.7 Location of Storage Vessel
The loss of heat increases in proportion to the length
of pipe between the storage vessel and the hot water
outlet since each time the water is drawn, the pipe fills
with hot water which then cools. The storage vessel
shall therefore be so placed that the pipe runs to the
most frequently used outlets are as short as possible.
4.13.8 Immersion Heater Installation
4.13.8.1 If a domestic storage vessel is to be adopted
to electric heating by the provision of an immersion
heater and thermostat, the following precautions shall
be observed:
a) Location of immersion heaters — The
immersion heater shall be mounted with its
axis horizontal, except in the case of the
circulation type which is normally mounted
with its axis approximately vertical.
b) In a tank with a flat bottom, a space of not
less than 75 mm below the immersion heater
and 50 mm below the cold feed connection
shall be provided to allow for accumulation
of sludge and scale, where it will not affect
the working of the immersion heater.
c) In a cylindrical storage vessel with inwardly
dished bottom, the inlet pipe shall be so
arranged that the incoming cold water is not
deflected directly into the hot water zone. The
lowest point of the immersion heater shall be
25 mm above the centre line of the cold feed
inlet, which, in turn, is usually 100 mm above
the cylinder rim.
d) Location of thermostat — Where the
thermostat does not form an integral part of
the immersion heater, it shall be mounted with
its axis horizontal, at least 50 mm away from
and not lower than the immersion heater.
e) Dual heater installations — If desired, the
principle of the dual heater may be adopted.
In this case, one heater and its thermostat shall
be installed at a low level as indicated in (b)
and (c). The second heater and its thermostat
shall be similarly disposed in the upper half
of the cylinder at a level depending on the
reserve of hot water desired for ordinary
domestic use. The bottom heater shall be
under separate switch control.
f) Clearance around storage vessel — Adequate
clearance shall be provided between the tank
and the cupboard, door or walls to allow
convenient insertion and adjustment of the
immersion heater and thermostat and to give
space for thermal insulation.
4.13.8.2 Rating of Immersion Heaters
The rating of an immersion heater shall be determined
according to the following factors:
a)
b)
c)
d)
proposed hot water storage capacity (the
maximum with cold water as indicated
in 4.13.3 shall be taken into account),
rate of utilization (draw off frequency),
permissible recovery period, and
inlet water temperature.
For details regarding rated input of water, refer to good
practice [9-1(14)].
4.13.9 Thermal Insulation
The hot water storage vessel and pipes shall be
adequately insulated wherever necessary to minimize
heat loss. The whole external surface of the storage
vessel including the cover to the handhole, shall be
provided with a covering equivalent to not less than
75 mm thickness of thermal insulating material having
a conductivity of not more than 0.05 W/(m 2 .°C)/mm
at mean temperature of 50°C.
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
33
4.13.10 Cold Water Supply to Heaters
4.13.10.1 A storage water heater (pressure type) shall
be fed from a cold water storage tank and under no
circumstances connected directly to the water main,
except the type which incorporates a feed tank with
ball valves and overflow pipe arrangement (cistern type
heaters) or non-pressure type heaters.
4.13.10.2 Storage cisterns
4.13.10.2.1 The storage capacity of a cold water tank
shall be at least twice the capacity of the hot water
heater. The capacity of the storage tank may, however,
be 1.5 times when the number of heaters connected to
one common tank exceeds 10.
4.13.10.2.2 The storage tank for supply of cold water
to hot water heaters shall be separate, if practicable. In
the case of a common tank which also supplies cold
water to the fixtures, this cold water supply connection
shall be so arranged that 50 percent of the net capacity,
worked out as in 4.13.10.2.1, shall be available for
supply to the hot water heaters.
4.13.10.2.3 In the case of multi- storey ed buildings
where a common overhead tank over the stair/lift well
is generally installed, it is advisable to have one or
more local tanks for supply to the hot water heaters.
This arrangement shall help in reducing the length of
the vent pipes (see Fig. 9).
4.13.10.2.4 In tall multi- storey ed buildings where the
static pressure increases with the height, the total static
pressure on the hot water heaters on the lowest floor
shall not exceed the rated working pressure of the hot
water heater installed. Should the height of the building
so require, additional tanks shall be provided on the
intermediate floors to restrict the static head to
permissible limits (see Fig. 10).
4.13.10.2.5 As an alternative to the arrangements
stated in 4.13.10.2.3 and 4.13.10.2.4 an individual
storage tank in each flat may be provided for supply
to hot water heaters (see Fig. 1 1).
4.13.11 Cold Water Feed
4.13.11.1 The feed pipe connecting cold water tank
with the hot water heater shall not be of less than 20 mm
bore and it shall leave the cold water tank at a point
not less than 50 mm above the bottom of the tank and
shall connect into the hot water heater near its bottom.
The feed pipe shall not deliver cold water to any other
connection, but into the hot water cylinders only.
4.13.11.2 In the case of multi-storeyed buildings, a
common cold water feed pipe may be installed, but
each hot water heater shall be provided with a check
valve (horizontal type check valve shall be preferred
to vertical type for easy maintenance).
4.13.11.3 Care shall be taken in installing the piping
to prevent air locks in the piping and negative pressure
in the hot water heater. Cold water feedpipe shall not
be cross connected with any other source of supply
under pressure (see Fig. 9).
4.13.12 Hot Water Piping
4.13.12.1 Expansion pipe or vent pipe
4.13.12.1.1 Each pressure type hot water heater or
cylinder shall be provided with a vent pipe of not less
than 20 mm bore. The vent pipe shall rise above the
water line of the cold water tank by at least 150 mm
plus 1 mm for every 300 mm height of the water line
above the bottom of the heater. The vent shall discharge
at a level higher than the cold water tank and preferably
in the cold water tank supplying the hot water heaters.
Care shall be taken to ensure that any accidental
discharge from the vent does not hurt or scald any
passerby or persons in the vicinity.
4.13.12.1.2 The vent pipe shall be connected to the
highest point of the heater vessel and it shall not
project downwards inside it, as otherwise air may be
trapped inside, resulting in surging and consequent
noises.
4.13.12.1.3 At no point, after leaving the vessel, shall
the vent pipe dip below the level of its connection with
the vessel.
4.13.12.1.4 A vent pipe may, however, be used for
supply of hot water to any point between the cold water
tank and the hot water heaters.
4.13.12.1.5 The vent pipe shall not be provided with
any valve or check valves.
4.13.12.2 Hot water heaters
4.13.12.2.1 The common hot water delivery pipe
shall leave the hot water heater near its top and shall
be of not less than 20 mm bore generally, not less
than 25 mm bore if hot water taps are installed on the
same floor as that on which the hot water heater is
situated.
4.13.12.2.2 Hot water taps shall be of such design as
would cause the minimum friction. Alternatively,
oversized tap may be provided, such as a 20 mm tap
on a 1 5 mm pipe.
4.13.12.2.3 The hot water distributing system shall be
so designed as to ensure that the time lag between
opening of the draw-off taps and discharge of hot water
is reduced to the minimum to avoid wastage of an
undue amount of water which may have cooled while
standing in the pipes when the taps are closed. With
this end in view, a secondary circulation system with
flow and return pipes from the hot water tank shall be
34
NATIONAL BUILDING CODE OF INDIA
-OVERHEAD TANK OVER STAIRWELL
v OR LIFT SHAFT COMMON FOR ALL SHAFTS
HWH
VENT
SUPPLY TO
S&LB
-WATER TANK OVER PLUMBING
.SHAFT INDIVIDUAL FOR EACH SHAFT
8th FLOOR
-MAIN TO
OVERHEAD TANK
Fig. 9 Installation for 8-Storeyed Building
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
35
-OVERHEAD TANK OVER STAIRWELL
\PR LIFT WELL COMMON FOR ALL SHAFTS
SUPPLY TO TANK No. 1,2.3
WATER TANK OVER PLUMBING
SHAFT INDIVIDUAL FOR EACH SHAFT
TANK 1 FLOOR 14-20
TANK 2 FLOOR 7 -13
TANK 3 FLOOR OF -6
HWH
VENT
v 14th TO 20th
* FLOOR
14th FLOOR
y
71hT013tti
FLOOR
7th FLOOR
GROUND FLOOR TO
6th FLOOR
LEGEND
-MAINTO COLD WATER SUPPLY
OVERHEAD TANK HOT WATER SUPPLY .
HOT WATER HEATER HWH
LAVATORY BASIN LB
SHOWER s
Fig. 10 Installation for 20-Storeyed Building
36
NATIONAL BUILDING CODE OF INDIA
-OVERHEAD TANK OVER STAIRWELL
OOR LIFT SHAFT COMMON FOR ALL SHAFTS
SUPPLY TO
OVERHEAD TANK
SUPPLY TO
TANKS
SUPPLY TO
LB&S
LEGEND
COLD WATER SUPPLY
HOT WATER SUPPLY
HOT WATER HEATER
LAVATORY BASIN
SHOWER
8th FLOOR
8th FLOOR
HWH
LB
S
GROUND FLOW
-MAIN TO
OVERHEAD TANK
Fig. 11 Installation for 8-Storeyed Building
with Individual Water Tanks
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
37
used where justified. Whether such a system is used
or not, the length of pipe to a hot water draw-off tap,
measured along the pipe from the tap to the hot water
tank or the secondary circulation pipe, shall not exceed
the lengths given in Table 8.
Table 8 Maximum Permissible Lengths of
Hot Water Draw-off Pipes
(Clause 4.13.12.23)
-OVERHEAD TANK
SI
No.
(1)
Largest Internal Diameter of Pipe
(2)
Length
m
(3)
i) Not exceeding 20 mm 12
ii) Exceeding 20 mm but not exceeding 25 mm 7.5
iii) Exceeding 25 mm 3.0
NOTE — Tn the case of a composite pipe of different
diameters, the largest diameter is to be taken into
consideration for the purpose of this table.
4.13.12.2.4 Wherever mixing of hot and cold water is
done by a mixing fitting, that is, hot and cold stop-cocks
deliver to a common outlet of mixed water (that is,
showers, basin or bath supply fittings), the pressure in
the cold and hot water systems shall be equal. This can
be achieved by connecting the cold water supply from
an overhead tank at the same static height as the overhead
tank supplying cold water to the hot water heaters. In
case this is not possible, hot and cold water should be
supplied to the fixtures by separate supply taps.
4.13.13 Types of Hot Water Heaters
The various types of water heaters used for preparation
of hot water are as follows:
a) Electric Storage Heaters:
1) Non-pressure or open outlet type,
2) Pressure type,
3) Cistern type, and
4) Dual heater type.
b) Gas Water Heaters:
1) Instantaneous type, and
2) Storage type.
c) Solar Heating Systems:
1 ) Independent roof mounted heating units,
and
2) Centrally banked heated system.
d) Central Hot Water System
1) Oil fired, and
2) Gas fired.
4.13.13.1 The quality and construction of the different
types of hot water heaters shall be in accordance with
good practice [9-1(15)].
4.13.13.2 Typical arrangement of water heater is
shown in Fig. 12.
X
F^=1
m
tZ&2ZZZZ?ZZZZ
"■^•-' -■: •
-SSL
y-'
J7
w&^zmm
^WATER
/ «/T HEATER
'Dl
E5S
■.- ,.,...:-y. -■ ••..... ... / ■■-,.
'//itf£Mt<i&&
WATER
HEATER
li
Fig. 12 Non-Pressure Type Installation
4.13.13.3 Requirements in regard to inspection and
maintenance of hot water supply installations shall be
in accordance with 4.14.1 to 4.14.4.
38
NATIONAL BUILDING CODE OF INDIA
4.14 Inspection and Testing
4.14.1 Testing of Mains Before Commencing Work
All pipes, fittings and appliances shall be inspected,
before delivery at the site to see whether they conform
to accepted standards. All pipes and fittings shall be
inspected and tested by the manufacturers at their
factory and shall comply with the requirements of this
Section. They shall be tested hydraulically under a
pressure equal to twice this maximum permissible
working pressure or under such greater pressure as may
be specified. The pipes and fittings shall be inspected
on site before laying and shall be sounded to disclose
cracks. Any defective items shall be clearly marked as
rejected and forthwith removed from the site.
4.14.2 Testing of Mains After Laying
After laying and jointing, the main shall be slowly and
carefully charged with water by providing a 25 mm
inlet with a stop-cock, so that all air is expelled from
the main. The main is then allowed to stand full of
water for a few days if time permits, and then tested
under pressure. The test pressure shall be 0.5 N/mm 2
or double the maximum working pressure, whichever
is greater. The pressure shall be applied by means of a
manually operated test pump, or, in the case of long
mains or mains of a large diameter, by a power-driven
test pump, provided the pump is not left unattended.
In either case, due precaution shall be taken to ensure
that the required test pressure is not exceeded. Pressure
gauges shall be accurate and shall preferably have been
recalibrated before the test. The pump having been
stopped, the test pressure shall maintain itself without
measurable loss for at least 5 min. The mains shall be
tested in sections as the work of laying proceeds; it is
an advantage to have the joints exposed for inspection
during the testing. The open end of the main may be
temporarily closed for testing under moderate pressure
by fitting a water-tight expanding plug of which several
types are available. The end of the main and the plug
shall be secured by struts or otherwise, to resist the
end thrust of the water pressure in the mains.
4.14.2.1 If the section of the main tested terminates
into a sluice valve, the wedge of the valve shall not be
used to retain the water; instead the valve shall be
temporarily fitted with a blank flange, or, in the case
of a socketed valve, with a plug, and the wedge placed
in the open position while testing. End support shall
be given as in 4.14.2.
4.14.3 Testing of Service Pipes and Fittings
When the service pipe is complete, it shall be slowly
and carefully charged with water, allowing all air to
escape, care being taken to avoid all shock or water
hammer. The service pipe shall then be inspected under
working conditions of pressure and flow. When all
draw-offs taps are closed, the service pipe shall be
absolutely water-tight. All piping, fittings and
appliances shall be checked for satisfactory support,
and protection from damage, corrosion and frost.
Because of the possibility of damage in transit, cisterns
shall be re-tested for water-tightness on arrival at the
site, before fixing.
4.14.4 In addition to the provisions given in 4.14.1,
provisions given in 4.14.4.1 to 4.14.4.3 shall also apply
to hot water supply installations in regard to inspection
and testing.
4.14.4.1 Testing of the system after installation
After the hot water system, including the hot water
heaters, has been installed, it shall be carefully charged
with water, so that all air is expelled from the system.
The entire system shall then be hydraulically tested to
a pressure of 0.5 N/mm 2 or twice the working pressure,
whichever is greater, for a period of at least half an
hour after a steady state is reached. The entire
installation shall then be inspected visually for
leakages, and sweating. All defects found shall be
rectified by removing and remaking the particular
section. Caulking of threads, hammering and welding
of leaking joints shall not be allowed.
4.14.4.2 Hot water testing
After the system has been proved water-tight, the hot
water heaters shall be commissioned by connecting
the same to the electrical supply. The system shall then
be observed for leakage in pipes due to expansion or
overheating. The temperature of water at outlets shall
be recorded. The thermostats of the appliances shall
be checked and adjusted to temperatures specified
in 4.13.2.1.
4.14.4.3 Electrical connection
For relevant provisions regarding general and safety
requirements for household and similar electrical
appliances, reference may be made to good practice
[9-1(14)]. The metal work of the water heating
appliances and installation other than current carrying
parts shall be bonded andearthed in conformity with
the good practice [9-1(14)]. It should be noted that
screwing of an immersion heater into a tank or cylinder
cannot be relied upon to effect a low resistance earth
connection, a satisfactory separate earthing of heater
should be effected.
4.15 Cleaning and Disinfection of the Supply
System
4.15.1 All water mains communications pipes, service
pipes and pipes used for distribution of water for
domestic purposes shall be thoroughly and efficiently
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
39
disinfected before being taken into use and also after
every major repair. The method of disinfection shall
be subject to the approval of the Authority. The pipes
shall also be periodically cleaned at intervals,
depending upon the quality of water, communication
pipes and the storage cisterns shall be thoroughly
cleaned at least once every year in order to remove
any suspended impurities that may have settled in the
pipes or the tanks.
4.15.2 Disinfection of Storage Tanks and Downtake
Distribution Pipes
The storage tanks and pipes shall first be filled with
water and thoroughly flushed out. The storage tank
shall then be filled with water again and a disinfecting
chemical containing chlorine added gradually while
the tanks are being filled, to ensure thorough mixing.
Sufficient quantities of chemicals shall be used to give
the water a dose of 50 parts of chlorine to one million
parts of water. If ordinary bleaching powder is used,
the proportions will be 150 g of powder to 1 000 litres
of water. The powder shall be mixed with water to a
creamy consistency before being added to the water
in the storage tank. When the storage tank is full, the
supply shall be stopped and all the taps on the
distributing pipes opened successively working
progressively away from the storage tank. Each tap
shall be closed when the water discharged begins to
smell of chlorine. The storage tank shall then be topped
up with water from the supply pipe and with more
disinfecting chemical in the recommended proportions.
The storage tank and pipes shall then remain charged
for at least 3 h. Finally, the tank and pipes shall be
thoroughly flushed out before any water is used for
domestic purposes.
4.16 Water Supply Systems in High Altitudes and/
or Sub-zero Temperature Regions
4.16.1 Selection and Source
In general, the site selected for a water source shall be
such as to minimize the length of transmission line so
as to reduce the inspection and upkeep. Attempt shall
be made, where feasible, to locate the source near the
discharge of waste heat, such as of power plants
provided it does not affect the potability of water.
4.16.2 Pumping Installation
Pump and pumping machinery shall be housed
inside well-insulated chambers. Where necessary,
arrangements shall be made for heating the inside of
pump houses. Pump houses, as far as possible, should
be built directly above the water intake structures.
4.16.3 Protection of Storage Water and Treatment
Where ambient temperatures are so low as to cause
danger of freezing, proper housing, insulation and
protection shall be provided for all processes and
equipment. If necessary, means shall be provided for
proper heating of the enclosure.
4.16.4 Transmission and Distribution
Freezing of the buried pipe may be avoided primarily
by laying the pipe below the level of the frost line;
well consolidated bedding of clean earth or sand, under,
around or over the pipe should be provided. For the
efficient operation and design of transmission and
distribution work, the available heat in the water shall
be economically utilized and controlled. If the heat
which is naturally present in water is made equate to
satisfy heat losses from the system, the water shall be
warmed. Where economically feasible, certain faucets
on the distribution system may be kept in a slightly
dripping condition so as to keep the fluid in motion
and thus prevent is freezing. If found unsuitable for
drinking purposes, such water may be used for heating
purposes. Heat losses shall be reduced by insulation,
if necessary. Any material that will catch, absorb or
hold moisture shall not be used for insulation purposes.
Adequate number of break pressure water tanks and
air release valves shall be provided in the distribution
system.
NOTE — The Level of frost Line is generally found to be between
0.9 m and 1.2 m below ground level in the northern regions of
India, wherever freezing occurs.
4.16.4.1 Materials for pipes
Distribution pipes shall be made of any of the following
materials conforming to Part 5 'Building Materials':
a) high density polyethylene pipes,
b) asbestos cement pipes,
c) galvanized iron pipes,
d) cast iron pipes, and
e) unplasticized PVC pipes (where it is laid
before frost line).
4.16.4.2 Materials for insulation of pipes
The normal practice in India is to surround the pipe
with straw, grass or jute wrapped over with gunny and
painted with bitumen; alternatively, other materials,
like 85 percent magnesia, glasswool, etc, may also be
used.
4.16.4.3 Distribution methods
Distribution by barrels or tank trucks shall be
employed, where the water requirements are temporary
and small. Utmost care shall be exercised for
preventing the water from being contaminated by
maintaining a residual of disinfecting agent at all times.
Hoses, pails and the tank shall be kept free from dust
and filth during all period of operation. Where winter
40
NATIONAL BUILDING CODE OF INDIA
temperatures are low, making frost penetration depths
greater during the winter, and where adequate facilities
for heating the water in the distribution system do not
exist, the use of tank trucks or barrels for delivery of
water shall be considered only for cold weather; during
the warm weather, piping system for seasonal use may
be supplemented.
4.16.4.4 In the conventional distribution system
involving the use of a network of pipelines requiring
no auxiliary heat, it is essential that the pipelines are
buried well below the frost line. Adequate facilities
for draining the pipelines shall be provided where there
is a danger of frost.
4.16.4.5 House service connections
House service connections shall be kept operative by
the use of adequate insulation at exposed places
extending below the frost line. Figure 10 shows a
typical arrangement for providing insulation for house
service connections.
4.16.5 For detailed information on planning and
designing water supply system peculiar to high
altitudes and/or sub-zero temperature regions of the
country, reference may be made to good practice
[9-1(16)].
4.17 Guidelines to Maintenance
4.17.1 Storage tanks shall be regularly inspected and
shall be cleaned out periodically, if necessary. Tanks
showing signs of corrosion shall be emptied,
thoroughly wire brushed to remove loose material (but
not scraped), cleaned and coated with suitable
bituminous compositions or other suitable anti-
corrosive material not liable to impart taste or odour
or otherwise contaminate the water. Before cleaning
the cistern, the outlets shall be plugged to prevent
debris from entering the pipes. Tanks shall be examined
for metal wastage and watertightness after cleaning.
4.17.2 Record drawings showing pipe layout and
valve positions shall be kept up to date and inspection
undertaken to ensure that any maintenance work has
not introduced cross-connections or any other
undesirable feature. Any addition or alterations to the
systems shall be duly recorded from time-to-time.
4.17.3 Any temporary attachment fixed to a tap or outlet
shall never be left in such a position that back-siphonage
of polluted water may occur into the supply system.
4.17.4 All valves shall periodically be operated to
maintain free movement of the working parts.
4.17.5 All taps and ball valves shall be watertight,
glands shall be made good, washers shall be replaced
and the mechanism of spring operated taps and ball
valves shall be repaired where required.
4.17.6 All overflow pipes shall be examined and kept
free from obstructions.
4.17.7 The electrical installation shall be checked for
earth continuity and any defects or deficiencies
corrected in the case of hot water supply installations.
5 DRAINAGE AND SANITATION
5.1 Types of Sanitary Appliances
5.1.1 Soil Appliances
5.1.1.1 Water-closet
It shall essentially consist of a closet consisting of a bowl
to receive excretory matter, trap and a flushing apparatus.
It is recommended to provide ablution tap adjacent to
the water-closet, preferably on right hand side wall. The
various types/style of water-closets may be:
a) Squatting Indian type water closet,
b) Washdown type water closet,
c) Siphonic washdown type water closet, and
d) Universal or Anglo-Indian water closet.
5.1.1.2 Bidet
It is provided with hot and cold water connection. The
bidet outlet should essentially connect to soil pipe in a
two-pipe system.
5.1.1.3 Urinal
It is a soil appliance and is connected to soil pipe after
a suitable trap. Urinal should have adequate provision
of flushing apparatus. The various types/style of urinal
may be:
a) Bowl type urinal: Flat back or Angle back,
b) Slab (single) type urinal,
c) Stall (single) type urinal,
d) Squatting plate type urinal, and
e) Syphon jet urinal with integral trap.
5.1.1.4 Slop sink and bedpan sink
Slop sink is a large sink of square shape. The appliance
is used in hospitals installed in the nurse's station,
operation theatres and similar locations for disposal
of excreta and other foul waste for washing bed pans
and urine bottles/pans. It is provided with a flushing
mechanism.
5.1.2 Waste Appliances
5.1.2.1 Washbasin
It is of one piece construction having a combined
overflow and preferably should have soap holding
recess or recesses that should properly drain into the
bowl. Each basin shall have circular waste hole through
which the liquid content of the basin shall drain.
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
41
5.1.2.2 Wash-trough
It is a linear trough for simultaneous use by number of
persons.
5.1.2.3 Sink
It is used in kitchen and laboratory for the purpose of
cleaning utensils/apparatus and also serve the purpose
of providing water for general usage. The sink may be
made with or without overflow arrangement. The sink
shall be of one piece construction including combined
over flow, where provided. The sink shall have a
circular waste hole into which the interiors of the sink
shall drain.
5.1.2.4 Bath tub
Bath tub may be of enamelled steel, cast iron, gel-
coated, glass fibre reinforced plastic or may be cast
in-situ. It shall be stable, comfortable, easy to get in
and out, water tight, with anti-skid base, and easy to
install and maintain. The bath tub shall be fitted with
overflow and waste pipe of nominal diameter of not
less than 32 mm and 40 mm respectively.
5.1.2.5 Drinking fountain
It is a bowl fitted with a push button tap and a water
bubbler or a tap with a swan neck outiet fitting. It has a
waste fitting, a trap and is connected to the waste pipe.
5.1.3 The requirements of various soil appliances and
waste appliances shall be in accordance with accepted
standards [9-1(17)].
5.2 Drainage and Sanitation Requirements
5.2.1 General
There should be at least one water tap and arrangement
for drainage in the vicinity of each water-closet or
group of water-closet in all the buildings.
5.2.2 Each family dwelling unit on premises (abutting
on a sewer or with a private sewage disposal system)
shall have, at least, one water-closet and one kitchen
type sink. A bath or shower shall also be installed to
meet the basic requirements of sanitation and personal
hygiene.
5.2.3 All other structures for human occupancy or use
on premises, abutting on a sewer or with a private
sewage-disposal system, shall have adequate sanitary
facilities, but in no case less than one water-closet and
one other fixture for cleaning purposes.
5.2.4 For Residences
5.2.4.1 Dwelling with individual convenience shall
have at least the following fitments:
a) One bathroom provided with a tap and a floor
trap;
b) One water-closet with flushing apparatus with
an ablution tap; and
c) One tap with a floor trap or a sink in kitchen
or wash place.
5.2.4.1.1 Where only one water-closet is provided in
a dwelling, the bath and water-closet desirably shall
be separately accommodated.
NOTE — Water-closets, unless indicated otherwise, shall be of
Indian style (squatting type).
5.2.4.2 Dwellings without individual conveniences
shall have the following fitments:
a) One water tap with floor trap in each
tenement,
b) One water-closet with flushing apparatus and
one ablution tap bath for every two tenements,
and
c) One bath with water tap and floor trap for
every two tenements.
5.2.5 For Buildings Other than Residences
5.2.5.1 The requirements for fitments for drainage and
sanitation in the case of buildings other than residences
shall be in accordance with Table 9 to Table 22. The
following shall be, in addition, taken into consideration:
a) The figures shown are based upon one (1)
fixture being the minimum required for the
number of persons indicated or part thereof.
b) Building categories not included in the
tables shall be considered separately by the
Authority.
c) Drinking fountains shall not be installed in
the toilets.
d) Where there is the danger of exposure to skin
contamination with poisonous, infectious or
irritating material, washbasin with eye wash
jet and an emergency shower located in an
area accessible at all times with the passage/
right of way suitable for access to a wheel
chair, shall be provided.
e) When applyiiig the provision of these
tables for providing the number of fixtures,
consideration shall be given to the accessibility
of the fixtures. Using purely numerical basis
may not result in an installation suited to the
need of a specific building. For example,
schools should be provided with toilet
facilities on each floor. Similarly toilet
facilities shall be provided for temporary
workmen employed in any establishment
according to the needs; and in any case one
WC and one washbasin shall be provided.
f) All buildings used for human habitation for
dwelling, work, occupation, medical care or
42
NATIONAL BUILDING CODE OF INDIA
Table 9 Office Buildings
(Clause 5.2.5.1)
SI
No
(I)
Fixtures
(2)
Public Toilets
Staff Toilets
Male
(3)
Females
(4)
Male
(5)
Females
(6)
Executive Rooms and Conference Halls
in Office Buildings
Toilet suite comprising one WC, one
washbasin (with optional shower stall if
building is used round the clock at user's
option)
Pantry optional as per user requirement
Unit could be common for Male/Female
or separate depending on the number of
user of each facility
For individual officer rooms
ii) Main Office Toilets for Staff and Visitors
a)
b)
Water-closets
Ablution tap with each water-closet
1 per 25
1 per 15 1 per 25
1 per 15
1 in each watei -closet
►
c)
Urinals
Add® 3% for
Add @ 2.5 %
Nil up to 6
1 for 7-20
2 for 2 1-45
3 for 46-70
4 for 71-100
101-200
Over 200
— Nil up to 6
d)
Washbasins
1 per 25
1 per 25 1 per 25
1 per 25
e)
Drinking water fountain
1 per 100
1 per 100 1 per 100
1 per 100
Cleaner's sink
«*— —
— — — 1 per floor
__ — „ — _►
Table 10 Factories
{Clause 5.2.5.1)
SI
Fixtures
Offices/Visitors
Workers
No
->V_
«-*-
<■***" "
^x
y"
~*v
Male
Female
Male
Female
(I)
(2)
(3)
(4)
(5)
(6)
i)
Water-closets
1 for up to 25
1 for up to 15
1 for up to 15
1 for up to 12
(Workers & Staff)
2 for 16-35
3 for 36-65
4 for 66- 100
2 for 16-25
3 for 26-40
4 for 41-57
5 for 58-77
6 for 78-100
2 for 16-35
3 for 36-65
4 for 66-100
2 for 13-25
3 for 26-40
4 for 41-57
5 for 58-77
6 for 78-100
For persons 1 1 -200 add
3%
5%
3%
5%
For persons over
200 add
2.5%
4%
2.50%
4%
ii)
Ablution tap
1 in each water-closet
1 in each water-closet
1 in each water-closet
1 in each water-closet
hi)
Urinals
Nil up to 6
1 for 7-20
2 for 21-45
3 for 46-70
4 for 71-100
Nil up to 6
1 for 7-20
2 for 21-45
3 for 46-70
4 for 71-100
For persons 101-200 add
3%
3%
For persons over
200 add
2.50%
2.50%
iv ) Washbasins
Washbasins in rows or troughs
v) Drinking water fountain
vi) Cleaner's sink
vii) Showers/Bathing rooms
viii) Emergency shower and eye
wash fountain
1 per 25 or part thereof 1 per 25 or part thereof 1 per 25 or part thereof 1 per 25 or part thereof
and taps spaced 750 mm c/c
1 per every 1 00 or part thereof with minimum 1 per every 1 00 or part thereof with minimum
one on each floor one on each floor
1 on each floor 1 on each floor 1 on each floor 1 on each floor
^ As per trade requirements ►
— — 1 per every shop floor per 500 persons
NOTE — For factories requiring workers to be engaged in dirty and dangerous operations or requiring them to being extremely clean
and sanitized conditions additional and separate (if required so) toilet facilities and if required by applicable Industrial and Safety Laws
and the Factories Act must be provided in consultation with the user.
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
43
Table 11 Cinema, Multiplex Cinema, Concerts and
Convention Halls, Theatres
(Clause 5.2.5.1)
SI
Fixtures
Public
Staff
No.
-A^
Male
Female
Male
"■ -^
Female
(1)
(2)
(3)
(4)
(5)
(6)
i)
Water-closets
1 per 100 up to 400
Over 400 add at 1 per
250 or part thereof
3 per 100 up to 200
Over 200 add at 2 per
100 or part thereof
1 for up to 15
1 for up to 12
ii)
Ablution tap
1 in each water-closet
1 in each water-closet
1 in each water-closet
1 in each water-closet
1 water tap with draining arrangements shall be provided for every 50 persons or part thereof in the
vicinity of water-closets and urinals
iii)
Urinals
1 per 25 or part thereof
Nil up to 6
1 for 7-20
2 for 21-45
iv)
Washbasins
1 per 200 oi
: part thereof
1 for up to 15
1 for up to 12
v) Drinking water fountain
vi) Cleaner's sink
vii) Showers/Bathing rooms
2 for 16-35
1 per 100 persons or part thereof
1 per floor
2 for 13-25
As per trade requirements
NOTES
1 Some WCs may be European style if desired.
2 Male population may be assumed as two-third and female population as one-third.
i) Water-closets
ii) Ablution tap
Table 12 Art Galleries, Libraries and Museums
(Clause 5.2.5.1)
SI
Fixtures
Public
Staff
No.
^_
_^
""
Male
Female
Male
Female
(1)
(2)
(3)
(4)
(5)
(6)
iii) Urinals
iv) Washbasins
v) Drinking water fountain
vi) Cleaner's sink
vii) Showers/Bathing rooms
1 per 200 up to 400
Over 400 add at 1 per
250 or part thereof
One in each water-
closet
1 per 100 up to 200
Over 200 add at 1 per
1 50 or part thereof
One in each water-
closet
1 for up to 15
2 for 16-35
One in each water-
closet
1 for up to 12
2 for 13-25
One in each water-
closet
1 water tap with draining arrangements shall be provided for every 50 persons or part thereof in the
vicinity of water-closets and urinals
1 per 50
1 for every 200 or part 1 for every 200 or part
thereof. For over 400, thereof. For over 200,
add at 1 per 250 persons add at 1 per 150 persons
or part thereof or part thereof
Nil up to 6
1 per 7 to 20
2 per 21-45
1 for up to 15
2 for 16-35
1 per 100 persons or part thereof
— 1 per floor, M in
1 for up to 12
2 for 13-25
As per requirements
NOTES
1 Some WCs may be European style if desired.
2 Male population may be assumed as two-third and female population as one-third.
44
NATIONAL BUILDING CODE OF INDIA
Table 13 Hospitals with Indoor Patient Wards
(Clause 5.2.5.1)
SI
Fixtures
Patient Toilets
Staff Toilets
Ma
r^
loiiet suite compnsing one
WC and one wsshbssin and
shower stall
For General Wards Hos n ital Staff and Visitors
Wfltpr-rln^pte 1 npr SK hprls nr narf
, , ^ 1 — r ™.
thereof
One in each water-
closet
iii) Ablution tap
Private room witn up to 4 patients
1 npr 8 hp.Hs nr nart
* 1 — 1
thereof
One in each water-
closet
ror individual doctor s/omcer s rooms
1 forun to 15
2 for 16-35
One in each water-
closet
1 for u n to 1 2
2 for 13-25
One in each water-
closet
i water tap witn draining arrangements snail oe proviaea ror every o\3 persons or pan inereor in ine
virinitv nf watp.r-clnspts and urinals
W\ TTrinals
v) Washbasins
1 npr ^0 hprk
2 for every 30 beds or part thereof. Add 1 per
additional 30 beds or part thereof
1 per ward
1 per ward
I per ward
1 per ward
Nil un to 6
1 for 7 to 20
2 for 21^5
1 for up to 15
2 for 16-35
1 for up to 12
2 for 13-25
vi) Dnnlcing water fountain
vii) Cleaner's sink
viii) Bed pan sink
ix) Kitchen sink
NOTES
1 Some WC's may be European style if desired.
2 Maie population may be assumed as two-third and female population as one-third.
3 Provision for additional and special hospital fittings where required shall be made.
i per iuu persons or part tnereor
Table 14 Hosnitals Outdoor Patient Department
ii)
(Tin
* * \\
SI
Fixtures
Patient Toilets
Staff Toilets
No.
_>^_
_^^_
■ — -% * —
-~*
Male
Female
Male Female
/"3\
i)
Toilet suite comprising one
1I7/~> 1 ... UU~„i~
vv\_ <uiu unc wasiiudMii
For up to 4 patients
For individual doctor's/officer's rooms
(with optional shower stall
if building used for 24 h)
Water-closets
iii) Ablution tap
iv) Urinals
1 per 100 persons or
part thereof
One in each water-
closet
2 per 100 persons or
part thereof
One in each water-
cioset
vicinity of water-closets and urinals
1 per 50 persons or
part thereof
1 for up to 15
2 for 16-35
One in each water-
closet
Nil up to 6
1 for 7 to 20
2 for 21-45
1 for up to 12
2 for 13-25
One in each water-
closet
v) Washbasins
vi) Drinking water fountain
1 per 100 persons or 2 per 100 persons or 1 for up to 15
part thereof part thereof
i per 500 persons or part thereof
1 for up to 1 2
per iuu persons or pan inereor
NOTES
1 Some WC's may be European style if desired.
2 Male population may be assumed as two-third and female population as one-third.
3 Provision for additional and special hospital fittings where required shall be made.
FAKT9 PLUMBING SERVICES — SECTION 1 WAl'EK SUFFLY, UKAlNAUtt AND SANITATION
<*Z>
Table 15 Hospitals, Administrative Buildings
(Clause 5.2.5.1)
SI
No.
<0
Fixtures
(2)
Staff Toilets
Male
(3)
Female
(4)
i) Toilet suite comprising one WC and one
washbasin (with optional shower stall if
building used for 24 h)
ii) Water-closets
hi) Ablution tap
iv) Urinals
For individual doctor's/officer's rooms
1 per 25 persons or part thereof
1 per 15 persons or part thereof
One in each water-closet One in each water-closet
1 water tap with draining arrangements shall be provided for every 50 persons or part
thereof in the vicinity of water-closets and urinals
Nil up to 6 —
1 for 7 to 20
2 for 21-45
v) Washbasins
vi) Drinking water fountain
vii) Cleaner's sink
viii) Kitchen sink
1 per 25 persons or part thereof 1 per 25 persons or part thereof
1 per 100 persons or part thereof
1 per floor, Min
1 per floor, Min
NOTE — Some WC\s may be European style if desired.
Table 16 Hospitals Staff Quarters and Nurses Homes
{Clause 5.2.5.1)
SI
No.
(1)
Fixtures
(2)
Staff Quarters
Nurses Homes
Male
(3)
Female
(4)
Male
(5)
Female
(6)
i) Water-closets
ii) Ablution tap
iii) Washbasins
iv) Bath (Showers)
v) Drinking water fountain
vi) Cleaner's sink
1 per 4 persons or part 1 per 4 persons or part 1 per 4 persons or part 1 per 4 persons or part
thereof thereof thereof thereof
2 for 16-35 2 for 13-25
One in each water- One in each water- One in each water- One in each water-
closet closet closet closet
1 water tap with draining arrangements shall be provided for every 50 persons or part thereof in the
vicinity of water-closets and urinals
1 per 8 persons or part thereof
1 per 4 persons or part thereof
1 per 100 persons or part thereof, minimum
1 per floor
1 per Floor
1 per 8 persons or part thereof
1 per 4 to 6 persons or part thereof
1 per 100 persons or part thereof, minimum
1 per floor
1 per Floor
NOTES
1 Some WC's may be European style if desired.
2 For independent housing units fixtures shall be provided as for residences.
46
NATIONAL BUILDING CODE OF INDIA
Table 17 Hotels
(Clause 5.2.5.1)
Si
No.
Fixtures
(2)
Fublic Rooms
Non-Residential Staff
(1)
Male Female
(3) (4)
"~""v *~~ '
Male Female
(5) (6)
■^
i)
Toilet suite comprising
one WC, Washbasin with
Shower or a Bath tub
Individual guest rooms with attached toiiets
—
Guest Rooms with Common Facilities
ii) Water-ciosets 1 per 100 persons up to 400
Over 400 add at 1 per 250 or
part thereof
iii) Ablution tap
iv) Urinals
v) Washbasins
vi) Bath (Showers)
vii) Cleaner's sink
viii) Kitchen sink
One in each water-closet
2 per 100 persons up to 200
Over 200 add at 1 per !00 or
part thereof
One in each water-closet
1 for uo to 15
2 for 16-35
3 for 36-65
4 for 66-100
One in each water-
closet
1 water tap with draining arrangements shall be provided for every 50 persons
vicinity of water-closets and urinals
1 per 50 persons or — Nil up to 6
part thereof l for 7 to 20
2 for 2 1-45
3 for 46-70
4for71-100
1 for up to 12
2 for 13-25
3 for 26-40
4 for 41-57
5 for 58=77
6 for 78-100
One in each water-
cioset
or part thereof in the
1 per WC/Urinal
1 per WC
1 per 10 persons or part thereof
1 for up to 15
2 for 16-35
3 for 36-65
4 for 66-100
1 for up to 12
2 for 13-25
3 for 26=40
4 for 4 1-57
1 per 30 rooms, minimum 1 per floor
1 per kitchen
NOTES
i Some WC's may be European style if desired.
2 Male population may be assumed as two-third and female population as one-third.
3 Provision for additional and special fittings where required shall be made.
Table 18 Restaurants
(Clause 5,2,5.1)
SI
No.
Fixtures
Public Rooms
Non-Residenuai Staff
Male
Female
* —
Male
Female
(i)
(2)
(3)
(4)
(5)
(6)
i)
Water-closets
I per 50 seats up to 200
Over 200 add at I per 100
or part thereof
2 per 50 seats up to 200
Over 200 add at 1 per 100
or part thereof
1 for up to 15
2 for 16-35
3 for 36-65
4 for 66-100
1 for up to 12
2 for 13-25
3 for 26-40
4 for 41-57
5 for 58-77
6 for 78-100
ii)
Ablution tap
One in each water- One in each water- One in each water-
closet closet closet
1 water tap with draining arrangements shall be provided for every 50 persons
of water-closets and urinals
One in each water-
closet
or part thereof in the vicinity
iii)
Urinals
1 per 50 persons or
part thereof
Nil up to 6
1 for 7 to 20
2 for 21-45
3 for 46-70
4 for 71-100
iv)
Washbasins
1 per WC
1 per WC
1 per WC
1 per WC
v)
Cleaner's sink
1 per each restaurant
vi)
Kitchen sink/Dish washer
1 per kitchen
NOTES
1 Some WC's may be European style if desired.
2 Male population may be assumed as two-third and female population as one-third.
3 Provision for additional and special fittings where required shall be made.
FART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
47
Table 19 Schools and Educational Institutions
(Clause 5.2.5.1)
SI
No.
Fixtures
Nursery School
Non-Residential
Residential
Boys
Girls
Boys
Girls
(1)
(2)
(3)
(4)
(5)
(6)
(7)
i)
Water-closets
1 per 15 pupils or
part thereof
1 per 40 pupils or
part thereof
1 per 25 pupils or
part thereof
1 per 8 pupils or
part thereof
1 per 6 pupils or
part thereof
ii)
Ablution tap
One in each water- One in each water- One in each water-
closet closet closet
1 water tap with draining arrangements shall be provided for every
water-closets and urinals
One in each water- One in each water-
closet closet
50 persons or part thereof in the vicinity of
iii)
Urinals
—
1 per 20 pupils or
part thereof
—
1 per 25 pupils or
part thereof
—
iv)
Washbasins
1 per 15 pupils or
part thereof
1 per 60 pupils or
part thereof
1 per 40 pupils or
part thereof
1 per 8 pupils or
part thereof
1 per 6 pupils or
part thereof
v)
Bath/Showers
1 per 40 pupils or
part thereof
—
—
1 per 8 pupils or
part thereof
1 per 6 pupils or
part thereof
vi)
Drinking water
fountain or taps
1 per 50 pupils or
part thereof
1 per 50 pupils or
part thereof
1 per 50 pupils or
part thereof
1 per 50 pupils or
part thereof
1 per 50 pupils or
part thereof
vii)
Cleaner's sink
1 per
each floor
NOTES
1 Some WC's may be European style if desired.
2 For teaching staff, the schedule of fixtures to be provided shall be the same as in case of office building.
Table 20 Hostels
(Clause 5.2.5.1)
SI
No.
Fixtures
(2)
Resident
Non-Resident
Visitor/Common Rooms
(1)
Males Females
(3) (4)
— S f~
Males
(5)
Females
(6)
Males
(7)
Females
(8)
i)
Water-closets
1 per 8 or part 1 per 6 or part 1 for up to 15
thereof thereof 2 for 16-35
3 for 36-65
4 for 66- 100
1 for up to 12
2 for 13-25
3 for 26-40
4 for 41-57
5 for 58-77
6 for 78-100
1 per 100
up to 400
Over 400 add at
1 per 250
2 per 100
up to 200
Over 200 add at
1 per 100
ii) Ablution tap
iii) Urinals
One in each One in each One in each One in each One in each One in each
water-closet water-closet water-closet water-closet water-closet water-closet
1 water tap with draining arrangements shall be provided for every 50 persons or part thereof in the vicinity of
water-closets and urinals
1 per 25 or part
thereof
Nil up to 6
1 for 7-20
2 for 21-45
3 for 46-70
4 for 71-100
1 per 50 or
part thereof
iv) Washbasins 1 per 8 persons 1 per 6 persons 1 for up to 15 1 for up to 12 1 per WC/Urinal 1 per WC
or part thereof or part thereof
2 for 16-35
3 for 36-65
4 for 66-100
2 for 13-25
3 for 26-40
4 for 41-57
5 for 58-77
6 for 78-100
v) Bath/Showers
vi) Cleaner's sink
1 per 8 persons
or part thereof
1 per 6 persons
or part thereof
1 per each floor
NOTE — Some WC's may be European style if desired.
48
NATIONAL BUILDING CODE OF INDIA
Table 21 Fruit and Vegetable Markets
(Clause 5.2.5.1)
SI
No.
Fixtures
(2)
Shop Owners
Common Toilets in Market
Building
Public Toilet for Floating
Population
(1)
Males Females
(3) (4)
Males
(5)
Females
(6)
Males
(7)
Females
(8)
i)
Water-closets
1 per 8 or part thereof
1 for up to 15
2 for 16-35
3 for 36-65
4 for 66-100
1 for up to 12
2 for 13-25
3 for 26-40
4 for 41-57
5 for 58-77
6 for 78-100
1 per 50,
(Minimum 2)
1 per 50,
(Minimum 2)
ii) Ablution tap
iii) Urinals
iv) Washbasins
One in each One in each One in each One in each One in each One in each
water-closet water-closet water-closet water-closet water-closet water-closet
1 water tap with draining arrangements shall be provided in receiving/sale area of each shop and for every 50
persons or part thereof in the vicinity of water-closets and urinals
1 per 8 percent or part thereof
v) Bath/Showers 1 per 8 persons or 1 per 6 persons or
part thereof part thereof
Nil up to 6
1 for 7-20
2 for 21-45
3 for 46-70
4 for 71-100
1 for up to 15
2 for 16-35
3 for 36-65
4 for 66-100
1 per 50
1 for up to 12
2 for 13-25
3 for 26-40
4 for 41-57
1 per 50 persons 1 per 50 persons
NOTES
1 Toilet facilities for individual buildings in a market should be taken same as that for office buildings.
2 Common toilets in the market buildings provide facilities for persons working in shops and their regular visitors.
3 Special toilet facilities for a large floating population of out of town buyers/sellers, labour, drivers of vehicles for whom special
toilet (public toilets).
Table 22 Airports and Railway Stations
(Clause 5.2.5.1)
SI
No.
Fixtures
Junction Stations, Intermediate
Stations and Bus Stations
Terminal Railway and Bus
Stations
Domestic and International
Airports
Males
Females
Males
Females
Males
Females
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
i)
Water-closets
3 for up to 1 000
Add 1 per
additional 1 000
or part thereof
4 for up to 1 000
Add 1 per
additional 1 000
or part thereof
4 for up to 1 000
Add 1 per
additional 1 000
or part thereof
5 for up to 1 000
Add 1 per
additional 1 000
or part thereof
Minimum 2
For 200 5
For 400 9
For 600 12
For 800 16
For 1000 18
Minimum 2
For 200 8
For 400 15
For 600 20
For 800 26
For 1 000 29
ii)
Ablution tap
One in each One in each One in each One in each One in each One in each
water-closet water-closet water-closet water-closet water-closet water-closet
1 water tap with draining arrangements shall be provided for every 50 persons or part thereof in the vicinity of
water-closets and urinals
iii)
Urinals
4 for up to 1 000
Add 1 per
additional 1 000
6 for up to 1 000
Add 1 per
additional 1 000
1 per 40 or part
thereof
iv)
Washbasins
1 per WC/Urinal
1 per WC
1 per WC/Urinal
1 perWC
1 per WC/Urinal
1 per WC
v)
Bath/Showers
2 per
1000
3 per
1000
4 per
1000
vi)
Drinking water
fountain or taps
(in common lobby
for male/female)
2 per 1 000 <
sr part thereof
3 per 1 000 or part thereof
4 per 1 000 or part thereof
vii)
Cleaner's sink
1 per toilet
compartment
with3WC's
1 per toilet
compartment
with 3 WC's
1 per toilet
compartment
with 3 WC's
1 per toilet
compartment
with 3 WC's
1 per toilet
compartment
with'3 WC's
1 per toilet
compartment
with" 3 WC's
viii)
Toilet for Disabled
1 per 4 000
1 per 4 000
1 per 4 000
1 per 4 000
1 per 4 000
(Minimum 1)
1 per 4 000
(Minimum 1)
NOTES
1 Some WC's may be European style if desired.
2 Male population may be assumed as three-fifth and female population as two-fifth.
3 Separate provision shall be made for staff and workers.
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
49
any purpose detailed in the various tables,
abutting a public sewer or a private sewage
disposal system, shall be provided with
minimum sanitary facilities as per the
schedule in the tables. In case the disposal
facilities are not available, they shall be
provided as a part of the building design for
ensuring high standards of sanitary conditions
in accordance with this section.
g) Workplaces where creches are provided, they
shall be provided with one WC for 1 persons
or part thereof, one washbasin for 15 persons
or part thereof, one kitchen sink with floor
trap for preparing food/milk preparations. The
sink provided shall with a drinking water tap.
h) In all types of buildings, individual toilets and
pantry should be provided for executives, and
for meeting/seminar/conference rooms, etc as
per the user requirement.
j) Where food is consumed indoors, water
stations may be provided in place of drinking
water fountains.
5.3 Materials, Fittings and Appliances
5.3.1 Standards for Materials, Fittings and Sanitary
Appliances
All materials, fittings and sanitary appliances shall
conform to Part 5 'Building Materials' .
5.3.2 Choice of Material for Pipes
5.3.2.1 Salt glazed stoneware pipe
For all sewers and drains in all soils, except where
supports are required as in made-up ground, glazed
stoneware pipe shall be used as far as possible in
preference to other types of pipes. These pipes are
particularly suitable where acid effluents or acid sub-
soil conditions are likely to be encountered. Salt glazed
stoneware pipes shall conform to accepted standards
[9-1(18)].
5.3.2.2 Cement concrete pipes
When properly ventilated, cement concrete pipes with
spigot and socket or collar joints present an alternative
to glazed stoneware sewers of over 150 mm diameter.
These shall not be used to carry acid effluents or sewage
under conditions favourable for the production of
hydrogen sulphide and shall not be laid in those sub-
soils that are likely to affect adversely the quality or
strength of concrete. Owing to the longer lengths of
pipes available, the joints would be lesser in the case
of cements concrete pipes. These pipes may be used
for surface water drains in all diameters. Cement
concrete pipes shall conform to accepted standards
[9-1(19)].
5.3.2.3 Cast iron pipes
5.3.2.3.1 These pipes shall be used in the following
situation:
a) in bed or unstable ground where soil movement
is expected;
b) in-made-up or tipped ground;
c) to provide for increased strength where a
sewer is laid at insufficient depth, where it is
exposed or where it has to be carried on piers
or above ground;
d) under buildings and where pipes are suspended
in basements and like situations;
e) in reaches where the velocity is more than
2.4 m/s; and
f) for crossings of watercourses.
NOTE — In difficult foundation condition such as in
the case of black cotton soil, the cast iron pipes shall be
used only when suitable supporting arrangements are
made.
5.3.2.3.2 It shall be noted that cast iron pipes even
when given a protective paint are liable to severe
external corrosion in certain soils; among such soils
are:
a) soils permeated by peaty waters; and
b) soils in which the sub-soil contains appreciable
concentrations of sulphates. Local experiences
shall be ascertained before cast iron pipes are
used where corrosive soil conditions are
suspected. Where so used, suitable measures
for the protection of the pipes may be resorted
to as an adequate safeguard.
5.3.2.3.3 Cast iron pipes shall conform to accepted
standards [9-1(20)].
5.3.2.4 Asbestos cement pipes
Asbestos cement pipes are commonly used for house
drainage systems and they shall conform to accepted
standards [9-1(21)]. They are not recommended for
underground situations. However, asbestos cement
pressure pipes conforming to accepted standards
[9-1(21)] may be used in underground situations also,
provided they are not subject to heavy superimposed
loads. These shall not be used to carry acid effluents
or sewage under conditions favourable for the
production of hydrogen sulphide and shall not be laid
in those sub-soils which are likely to affect adversely
the quality or strength of asbestos cement pipes. Where
so desired, the life of asbestos cement pipes may be
increased by lining inside of the pipe with suitable
coatings like epoxy/polyester resins etc.
5.3.2.6 PVC pipes
Unplasticized PVC pipes may be used for drainage
50
NATIONAL BUILDING CODE OF INDIA
purposes; however, where hot water discharge is
anticipated, the wall thickness shall be minimum 3 mm
irrespective of the size and flow load.
PVC and HDPE pipes shall conform to accepted
standards [9-1(23)].
NOTE — Where possible, high density polyethylene pipes
(HDPE) and PVC pipes may be used for drainage and sanitation
purposes, depending upon the suitability.
5.4 Preliminary Data for Design
5.4.1 General
Before the drainage system for a building or group of
buildings is designed and constructed, accurate
information regarding the site conditions is essential.
This information may vary with the individual scheme
but shall, in general, be covered by the following:
a) Site Plan (see 3.3.2).
b) Drainage Plan (see 3.3.3).
c) Use — A description of the use for which
the building is intended and periods of
occupation in order that peak discharges may
be estimated;
d) Nature of Waste — While dealing with
sewage from domestic premises, special
problems under this head may not arise;
however, note shall be taken of any possibility
of trade effluents being discharged into the
pipes at a future date;
e) Outlet Connection — The availability of
sewers or other outlets;
f) Cover — The depth (below ground) of the
proposed sewers and drains and the nature and
weight of the traffic on the ground above
them;
g) Sub-soil Condition:
1) The approximate level of the subsoil
water, and any available records of flood
levels shall be ascertained, as also the
depth of the water table relative to all
sewer connections, unless it is known to
be considerably below the level of the
latter;
2) In the case of deep manholes, this
information will influence largely the
type of construction to be adopted. The
probable safe bearing capacity of the sub-
soil at invert level may be ascertained in
the case of a deep manhole.
3) Where work of any magnitude is to be
undertaken, trial pits or boreholes shall
be put at intervals along the line of the
proposed sewer or drain and the data
therefrom tabulated, together with any
information available from previous
works carried out in the vicinity. In
general the information derived from trial
pits is more reliable than that derived
from boreholes. For a long length of
sewer or drain, information derived from
a few trial pits at carefully chosen points
may be supplemented by that obtained
from number of intermediate boreholes.
Much useful information is often obtained
economically and quickly by the use of
a soil auger;
4) The positions of trial pits or boreholes
shall be shown on the plans, together with
sections showing the strata found and the
dates on which water levels are recorded.
h) Location of Other Services — The position,
depth and size of all other pipes, mains,
cables, or other services, in the vicinity of the
proposed work, may be ascertained from the
Authority, if necessary;
j) Reinstatement of Surfaces — Information
about the requirements of the highway
authority is necessary where any part of the
sewer or drain is to be taken under a highway.
Those responsible for the sewer or drain shall
be also responsible for the maintenance of the
surface until permanently reinstated. The
written consent of the highway authority to
break up the surface and arrangement as to
the charges thereof and the method and type
of surface reinstatement shall always be
obtained before any work is commenced;
k) Diversion and Control of Traffic
1) In cases where sewers cross roads or foot-
paths, cooperation shall be maintained
with the police and Authorities regarding
the control and diversion of vehicular
and/or pedestrian traffic as may be
necessary. Access to properties along the
road shall always be maintained and
adequate notice shall be given to the
occupiers of any shops or business
premises, r/articularly if obstruction is
likely;
2) During the period of diversion, necessary
danger lights, red flags, diversion boards,
caution boards, watchmen, etc, shall be
provided as required by the Authority;
m) Way-leaves (Easements) — The individual or
authority carrying out the work is responsible
for negotiating way-leaves where the sewer
crosses land in other ownership. The full
extend and conditions of such way-leaves
shall be made known to the contractor
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
51
and his employees, and prior notice of
commencement of excavation shall always
be given to the owners concerned, and
cooperation with them shall be maintained at
all stages, where sewers run across fields or
open ground, the exact location of manholes
shall be shown on way-leaves or easement
plans. The right of access to manhole covers
and the right to maintain the sewer shall be
specifically included in any way-leave or
easement arrangements which may be made
with the owner of the land; and
n) Damage to Buildings and Structures — When
sewer trenches have to be excavated near
buildings or walls a joint inspection with the
owners of the property shall be made to
establish whether any damage or cracks exist
before starting the work, and a properly
authenticated survey and record of the
condition of buildings likely to be affected
shall be made. Tell tales may be placed across
outside cracks and dated, and kept under
observation. Un-retouched photographs taken
by an independent photographer may provide
useful evidence.
5.4.2 Drainage into a Public Sewer
Where public sewerage is available, the following
information is particularly necessary and may be
obtained from the Authority:
a) the position of the public sewer or sewers in
relation to the proposed buildings;
b) the invert level of the public sewer;
c) the system on which the public sewers are
designed (combined, separate or partially
separate), the lowest level at which
connection may be made to it, and the
Authority in which it is vested;
d) the material of construction and condition of
the sewer if connection is not to be made by
the Authority;
e) the extent to which surcharge in the sewer
may influence the drainage scheme;
f) whether the connection to the public sewer is
made, or any part of the drain laid, by the
Authority, or whether the owner is responsible
for this work; if the latter, whether the
Authority imposes any special conditions;
g) whether an intercepting trap is required by
the Authority on the drain near the boundary
of the curtilage; and
h) where manholes are constructed under roads,
the approval of the Highway Authority for
the type of cover to be fitted shall be obtained.
5.4.3 Other Methods of Disposal of Sewage
5.4.3.1 Where discharge into a public sewer is not
possible, the drainage of the building shall be on a
separate system. Foul water shall be disposed of by
adequate treatment approved by the Authority on the
site. The effluent from the plant shall be discharged
into a natural watercourse or on the surface of the
ground or disposed of sub-soil dispersion preferably
draining to a suitable outlet channel.
5.4.3.2 In the case of dilution into a natural stream
course, the quality of the effluent shall conform and
the requirements of the Authority controlling the
prevention of pollution of streams.
5.4.3.3 In the case of sub-soil dispersion, the
requirements of the Authority for water supply shall
be observed to avoid any possible pollution of local
water supplies or wells.
5.43.4 The general sub-soil water level and the subsoil
conditions shall be ascertained, including the
absorptive capacity of the soil.
5.4.3.5 A sub-soil dispersion is not desirable near a
building or in such positions that the ground below
the foundations is likely to be affected.
5.4.3.6 Where no other method of disposal is possible,
foul water may be diverted to cesspools and
arrangements made with the Authority for satisfactory
periodical removal and conveyance to a disposal
works.
5.4.3.7 Under the separate system, drainage of the
building shall be done through septic tanks of different
sizes or by stabilization ponds or by any other methods
approved by the Authority.
For detailed information on the design and construction
of septic tanks and waste stabilization ponds, reference
may be made to good practice [9-2(24)].
5.4.4 Disposal of Surface and Sub-soil Waters
All information which may influence the choice of
methods of disposal of surface and/or sub-soil waters
shall be obtained. In the absence of surface water
drainage system, and if practicable and permissible,
disposal into a natural water-course or soakaway may
be adopted. The location and flood levels of the water
course as also the requirements of the Authority
controlling the river or the waterway shall be
ascertained.
5.5 Planning and Design Considerations
5.5.1 Aim
The efficient disposal of foul and surface water from a
building is of great importance to public health and is
52
NATIONAL BUILDING CODE OF INDIA
an essential part of the construction of the building. In
designing a drainage system for an individual building
or a housing colony, the aim shall be to provide a
system of self-cleaning conduits for the conveyance
of foul, waste, surface or subsurface waters and for
the removal of such wastes speedily and efficiently to
a sewer or other outlet without risk of nuisance and
hazard to health.
5.5.1.1 To achieve this aim a drainage system shall
satisfy the following requirements:
a) rapid and efficient removal of liquid wastes
without leakage;
b) prevention of access of foul gases to the
building and provision for their escape from
the system.
c) adequate and easy access for clearing
obstructions;
d) prevention of undue external or internal
corrosion, or erosion of joints and protection
of materials of construction; and
e) avoidance of air locks, siphonage, proneness
to obstruction, deposit and damage.
5.5.1.2 The realization of an economical drainage
system is added by compact grouping of fitments in
both horizontal and vertical directions. This implies
that if care is taken and ingenuity brought into play
when designing the original building or buildings to
be drained, it is possible to group the sanitary fittings
and other equipment requiring drainage; both in
vertical and horizontal planes, as to simplify the
drainage system and make it most economical.
5.5.1.3 Efficient and an economical plumbing system
can be achieved by planning the toilets in compact
grouping with the layout of the bathrooms and
observing the following guidelines:
a) Placing of plumbing fixtures around an easily
accessible pipe shaft; in high rise buildings
the pipe shafts may have to be within the
building envelope and easy provision for
access panels and doors should be planned in
advance, in such cases.
b) Adopting repetitive layout of toilets in the
horizontal and vertical directions.
c) Avoiding any conflict with the reinforced
cement concrete structure by avoiding
embedding pipes in it, avoiding pipe crossings
in beams, columns and major structural
elements.
d) Identifying open terraces and areas subject to
ingress of rainwater directly or indirectly and
providing for location of inlets at each level
for down takes for disposal at ground levels.
e) Avoiding crossing of services of individual
property through property of other owners.
f) Planning to avoid accumulation of rain water
or any backflow from sewers particularly in
planned law elevation areas in a building.
5.5.2 Layout
5.5.2.1 General
Rain-water should preferably be dealt separately from
sewage and sullage. Sewage and sullage shall be
connected to sewers. However, storm water from the
courtyard may be connected to the sewer where it is
not possible to drain otherwise; after obtaining
permission of the Authority.
5.5.2.2 Additional Requirement
The following requirements are suggested to be
considered in the design of drainage system:
a) The layout shall be as simple and direct as
practicable.
b) The pipes should be laid in straight lines, as
far as possible, in both vertical and horizontal
planes.
c) Anything that is likely to cause irregularity
of flow, as abrupt changes of direction, shall
be avoided.
d) The pipes should be non-absorbent, durable,
smooth in bore and of adequate strength.
e) The pipes should be adequately supported
without restricting movement.
f) Drains should be well ventilated, to prevent
the accumulation of foul gases and fluctuation
of air pressure within the pipe, which could
lead to unsealing of gully or water-closet traps.
g) All the parts of the drainage system should
be accessible for feasibility of inspection and
practical maintenance.
h) No bends and junctions whatsoever shall be
permitted in sewers except at manholes and
inspection chambers.
j) Sewer drain shall be laid for self-cleaning
velocity of 0.75 -m/s and generally should not
flow more than half-full.
k) Pipes crossing in walls and floors shall be
through mild steel sleeves of diameter leaving
an annular space of 5 mm around the outer
diameter of the pipe crossing the wall,
m) Pipes should not be laid close to building
foundation,
n) Pipes should not pass near large trees because
of possibility of damage by the roots.
p) Branch connections should be swept in the
direction of flow.
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
53
q) Sewer pipes should be at least 900 mm below
road and at least 600 mm below fields and
gardens.
r) Pipes should not pass under a building unless
absolutely necessary.
Where it is necessary to lay pipes under a
building, the following conditions shall be
observed:
1) Pipes shall be centrifugally cast (spun)
iron pressure pipe as per good practice
[9-2(20)];
2) The pipe shall be laid in straight line and
at uniform gradient;
3) Means of access in form of manholes/
inspection chamber shall be provided at
each end, immediately outside the
building; and
4) In case the pipe or any part of it is laid
above the natural surface of the ground,
it shall be laid on concrete supports, the
bottom of which goes at least 150 mm
below the ground surface.
NOTE — It is desirable that pipe/drains should not
be taken through a living room or kitchen and shall
preferably be taken under a staircase room or
passage.
s) Consideration shall be given to alternative
layouts so as to ensure that the most economical
and practical solution is adopted. The
possibility of alterations shall be avoided by
exercising due care and forethought.
5.5.2.3 Protection against vermin and dirt
The installation of sanitary fittings shall not introduce
crevices which are not possible to inspect and clean
readily.
Pipes, if not embedded, shall be run well clear of the
wall. Holes through walls to taken pipes shall be made
good on both sides to prevent entry of insects. Materials
used for embedding pipes shall be rodent-proof.
Passage of rodents from room-to-room or from floor-
to-floor shall be prevented by suitable sealing. The
intermediate lengths of ducts and chases shall be
capable of easy inspection. Any unused drains, sewers,
etc, shall be demolished or filled in to keep them free
from rodents.
All pipe shafts shall be plastered before any pipes are
installed in the shaft. This will provide a smooth surface
and prevent location for survival of insects and
vermins.
5.5.2.4 Choice of plumbing system
In selecting one or more of the type of piping systems,
the building and the layout of toilets; relationship with
other services; acceptability to the Authority; and any
special requirements of users, shall be studied.
a) Two-pipe system
1 ) This system is ideal when the location of
toilets and stacks for the WCs and waste
fittings is not uniform or repetitive.
2) In large buildings and houses with open
ground and gardens the sullage water
from the waste system can be usefully
utilized for gardening and agriculture.
3) In larger and multi-storied buildings, the
sullage is treated within the building for
re-use as makeup water for cooling towers
for air conditioning system and is also used
for flushing water-closets provided it has
absolutely no connection with any water
supply line, tank or system used for
domestic and drinking supply.
b) One-pipe system
1) This system is suitable for buildings
where the toilet layouts and the shafts are
repetitive. It requires less space, and is
economical.
2) Continuous flow of water in the pipe
from waste appliances makes it less prone
to blockage and makes the system more
efficient.
3) The system eliminates the need for a
gully trap which requires constant
cleaning.
4) The system is ideal when the main pipes
run at the ceiling of the lowest floor or in
a service floor. Two-pipe system may
present space and crossing problems
which this system eliminates.
c) Single stack system
1 ) The single stack system (without any vent
pipe) is ideal when the toilet layouts are
repetitive and there is less space for pipes
on the wall.
2) In any system so selected there should
be not more than two toilet connections
per floor.
3) The system requires minimum 100 mm
diameter stack for a maximum of five
floors in a building.
4) All the safeguards for the use of this
system given in 5.5.2.4.1 shall be
complied with.
d) Single stack system (partially ventilated)
The system and the applicable safeguards
under this system are the same as for single
stack system. The prime modification is to
54
NATIONAL BUILDING CODE OF INDIA
connect the waste appliances, such as wash
basin, bath tub or sink to a floor trap.
For detailed information regarding design and
installation of soil, waste and ventilating pies, reference
may be made to good practice [9-2(25)].
5.5.2.4.1 Safeguards for single stack system
a) as far as practicable, the fixtures on a floor
shall be connected to stack in order of
increasing discharge rate in the downward
direction;
b) the vertical distance between the waste branch
(from floor trap or from the individual
appliance) and the soil branch connection,
when soil pipe is connected to stack above
the waste pipe, shall be not less than 200 mm;
c) depth of water seal traps from different
fixtures shall be as follows:
Water closets 50 mm
Floor traps 50 mm
Other fixtures directly connected to the
stack.
1) Where attached to branch 40 mm
waste pipes of 75 mm dia
or more
2) Where attached to branch 75 mm
waste pipes of less than
75 mm dia
NOTE — When connection is made through floor
trap, no separate seals are required for individual
fixtures.
d) branches and stacks which receive discharges
from WC pans should not be less than
100 mm, except where the outlet from the
siphonic water closet is 80 mm, in which case
a branch pipe of 80 mm may be used. For
outlet of floor traps 75 mm dia pipes may be
used;
e) the horizontal branch distance for fixtures
from stack, bend(s) at the foot of stack to
avoid back pressure as well as vertical
distance between the lowest connection and
the invert of drain shall be as shown in
Fig. 2 A; and
f) for tall buildings, ground floor appliances are
recommended to be connected directly to
manhole/inspection chamber.
5.5.3 Drainage (Soil, Waste and Ventilating) Pipes
5.5.3.1 General considerations
5.5.3.1.1 Drainage pipes shall be kept clear of all other
services. Provisions shall be made during the
construction of the building for the entry of the
drainage pipes. In most cases this may be done
conveniently by building sleeves or conduit pipes into
or under the structure in appropriate positions. This
will facilitate the installation and maintenance of the
services.
5.5.3.1.2 Horizontal drainage piping should be so
routed as not to pass over any equipment or fixture
where leakage from the line could possibly cause
damage or contamination. Drainage piping shall never
pass over switch-gear or other electrical equipment. If
it is impossible to avoid these areas and piping must
run in these locations, then a pan or drain tray should
be installed below the pipe to collect any leakage or
condensation. A drain line should run from this pan to
a convenient floor drain or service sink.
5.5.3.1.3 All vertical soil, waste, ventilating and anti-
siphonage pipes shall be covered on top with a copper
or heavily galvanized iron wire dome or cast iron
terminal guards. All cast iron pipes, which are to be
painted periodically, shall be fixed to give a minimum
clearance of 50 mm clear from the finished surface of
the wall by means of a suitable clamps.
NOTE — Asbestos cement cowls may be used in case asbestos
cement pipes are used as soil pipes.
5.5.3.1.4 Drainage pipes shall be carried to a height
above the buildings as specified for ventilating pipe
(see 5.5.3.4).
5.5.3.2 Soil pipes
A soil pipe, conveying to a drain, any solid or liquid
filth, shall be circular and shall have a minimum
diameter of 100 mm.
5.5.3.2.1 Except where it is impracticable, the soil pipe
shall be situated outside the building or in suitably
designed pipe shafts and shall be continued upwards
without diminution of its diameter, and (except where
it is unavoidable) without any bend or angle, to such a
height and position as to afford by means of its open
end a safe outlet for foul air. The position of the open
end with its covering shall be such as to comply with
the conditions set out in 5.5.3.4 relating to ventilating
pipe. Even if the pipes are lajtd externally, the soil pipes
shall not be permitted on a wall abutting a street unless
the Authority is satisfied that it is unavoidable. Where
shafts for pipes are provided, the cross-sectional area
of the shaft shall be suitable to allow free and
unhampered access to the pipes and fittings proposed
to be installed in the shaft. However in no case cross-
section area of the shaft shall be less than a square of
one meter side. All pipe shafts shall be provided with
an access door at ground level and facilities for
ventilation.
5.5.3.2.2 Soil pipes, whether insider or outside the
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
55
building, shall not be connected with any rain-
water pipe and there shall not be any trap in such soil
pipe or between it and any drain with which it is
connected.
5.5.3.2.3 Soil pipes shall preferably be of cast iron.
Asbestos cement building pipes may also be used as
soil pipes only above ground level.
5.5.3.2.4 The soil pipe shall be provided with heel rest
bend which shall rest on sound footing, if terminating
at firm ground level. When the stack is terminating at
the ceiling of a floor, the bend shall be provided with
sufficient structural support to cater for the stack dead
weight and the thrust developed from the falling soil/
waste. Vertical stack shall be fixed at least 50 mm clear
of the finished surface of the wall by means of a suitable
clamps of approved type.
5.5.3.3 Waste pipes
Every pipe in a building for carrying off the waste or
overflow water from every bath, washbasin or sink to
a drain shall be of 32 mm to 50 mm diameter, and shall
be trapped immediately beneath such washbasins or
sink by an efficient siphon trap with adequate means
for inspection and cleaning. Such traps shall be
ventilated into the external air whenever such
ventilation is necessary to preserve the seal of the trap.
Waste pipes, traps, etc, shall be constructed of iron,
lead, brass, stoneware, asbestos cement or other
approved material. The overflow pipe from washbasin,
sinks, etc, shall be connected with the waste pipe
immediately above the trap. Vertical pipes carrying
off waste water shall have a minimum diameter of
15 mm.
NOTE — Whenever washbasins and sinks have in-built
overflow arrangements, there is no need to provide overflow
pipes in such cases.
5.5.3.3.1 Every pipe in a building for carrying off
waste water to a drain shall be taken through an external
wall of the building by the shortest practicable line,
and shall discharge below the grating or surface box
of the chamber but above the inlet of a properly trapped
gully. The waste pipe shall be continued upwards
without any diminution in its diameter and (except
when unavoidable) without any bend or angle to such
a height and position as to afford by means of the open
end of the waste pipe, a safe outlet for foul air, the
position of the open end and its covering being such
as to comply with the conditions.
5.5.3.3.2 Except where it is impracticable, the
common waste pipe shall be situated outside the
building and shall be continued upwards without
diminution of its diameter (except where it is
unavoidable) without any bend or angle being formed
to such a height and position as to avoid by means of
the open end a safe outlet for foul air, the position of
the open end and the covering threat being such as to
comply with the conditions set out in 5.5.3.4 relating
to ventilating pipe.
5.5.3.3.3 If the waste pipe is of cast iron, it shall be
firmly attached 50 mm clear of the finished surface of
the wall by means of a suitable clamps or with properly
fixed holder bats or equally suitable and efficient
means.
5.5.3.4 Ventilating pipes
Ventilating pipes should be so installed that water
can not be retained in them. They should be fixed
vertically. Whenever possible, horizontal runs
should be avoided. Ventilating pipe shall be carried
to such a height and in such a position as to afford
by means of the open end of such pipe or vent shaft,
a safe outlet for foul air with the least possible
nuisance.
5.5.3.4.1 The upper end of the main ventilating pipe
may be continued to the open air above roof level as a
separate pipe, or it may join the MSP and/or MWP
above the floor level of the highest appliance. Its lower
end may be carried down to join the drain, at a point
where air relief may always be maintained.
5.5.3.4.2 Branch ventilating pipes should be connected
to the top of the BSP and BWP between 15 mm and
450 mm from the crown of the trap.
5.5.3.4.3 The ventilating pipe shall always be taken
to a point 1500 mm above the level of the eaves or flat
roof or terrace parapet whichever is higher or the top
of any window within a horizontal distance of 3 m.
The least dimension shall be taken as a minimum and
local conditions shall be taken into account. The upper
end of every ventilating pipe shall be protected by
means of a cowl.
5.5.3.4.4 In case the adjoining building is taller, the
ventilating pipe shall be carried higher than the roof
of the adjacent building, wherever it is possible.
5.5.3.4.5 The building drain intended for carrying
waste water and sewage from a building shall be
provided with at least one ventilating pipe situated as
near as practicable to the building and as far away as
possible from the point at which the drain empties into
the sewer or other carrier.
5.5.3.4.6 Size of ventilating pipe
a) The building drain ventilating pipe shall be
of not less than 15 mm diameter when,
however, it is used as MSP or MWP. The
upper portion, which does not carry discharges,
shall not be of lesser diameter than the
remaining portion;
56
NATIONAL BUILDING CODE OF INDIA
b)
c)
d)
The diameter of the main ventilating pipe in
any case should not be less than 50 mm;
A branch ventilating pipe on a waste pipe in
both one-and two-pipe systems shall be of not
less than two-thirds the diameter of the branch
waste ventilated pipe; subject to a minimum
of 25 mm; and
A branch ventilating pipe on a soil pipe in
both one-and two-pipe systems shall be not
less than 32 mm in diameter.
5.5.3.5 Design of drainage pipes
5.5.3.5.1 Estimation of maximum flow of sewer
a) Simultaneously discharge flow
1) The maximum flow in a building drain
or a stack depends on the probable
maximum number of simultaneously
discharging appliances. For the calculation
of this peak flow certain loading factors
have been assigned to appliances in
terms of fixture units, considering
their probability and frequency of use.
These fixture unit values are given in
Table 23.
2) For any fixtures not covered under
Table 23, Table 24 may be referred to
for deciding their fixture unit rating
depending on their drain or trap size,
3) From Tables 23 and 24, the total load on
any pipe in terms of fixtures units may
be calculated knowing the number and
type of appliances connected to this pipe,
4) For converting the total load in fixture
units to the peak flow in litres per minute,
Fig. 13 is to be used.
5) The maximum number of fixture units
that are permissible various recommended
pipe size in the drainage system are given
in Tables 25 and 26.
6) Results should be checked to see that the
soil, waste and building sewer pipes are
not reduced in diameter in the direction
of flow. Where appliances are to be added
in fixture, these should be taken into
account in assessing the pipe sizes by
using the fixture units given in Tables 23
and 24,
b) Maximum discharge flow — The maximum
rate of discharge flow shall be taken as thrice
the average rate, allowance being made in
addition for any exceptional peak discharges.
A good average pale is to allow for a flow of
liquid wastes from buildings at the rate of
3 litres per minute per 10 persons.
5.5.3.5.2 Gradients
5.5.3.5.2.1 The discharge of water through a
domestic drain is intermittent and limited in quantity
and, therefore, small accumulations of solid matter
are liable to form in the drains between the building
and the public sewer. There is usually a gradual
shifting of these deposits as discharges take place.
Gradients should be sufficient to prevent these
temporary accumulations building up and blocking
the drains.
Table 23 Fixture Units for Different Sanitary
Appiiances or Croups
(Clause 5.5.3.5.1)
SI
Type of Fixture
Fixture
No.
Unit Value
as Load
Factors
(1)
(2)
(3)
i)
One bathroom group consisting of water-
closet, washbasin and bath tub or shower
stall:
a) Tank water-closet
6
b) Flush-valve water-closed
8
")
Bathtub 1 *
3
iii)
Bidet
3
iv)
Combination sink-and-tray (drain board)
3
v)
Drinking fountain
Yi
vi)
Floor traps 2)
1
vii)
Kitchen sink, domestic
2
viii)
Wash basin, ordinary 3 '
1
ix)
Wash basin, surgeon's
2
x)
Shower stall, domestic
2
xi)
Showers (group) per head
3
xii)
Urinal, wall lip
4
xiii)
Urinal, stall
4
xiv)
Water-closet, tank-operated
4
XV )
Water-closet, valve-operated
8
1 A shower head over a bath tub does not increase the fixture
unit value.
3) Size of floor trap shall be determined by the area of surface
water to be drained.
3 > Washbasins with 32 mm and 40 mm trap have the same load
value.
Table 24 Fixture Unit Values for Fixtures
Based on Fixture Drain on Trap Size
(Clause 5.5.3.5.1)
S!
Fixture Drain on Trap Size
Fixture
No.
Unit Value
(0
. ( 2 >
(3)
i)
32 mm and smaller
1
ii)
40 mm
2
iii)
50 mm
3
iv)
65 mm
4
v)
80 mm
5
vi)
100 mm
6
PART* PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
57
laDie zs Maximum rsumoer 01 fixture units tnai can oe ^onneciea 10
Branches and Stocks
(Clause 5.5.3.5.1)
SJ
Diameter
Maximum Number of Fixture Units
1} that can be Connected
No.
of Pipe
Any Horizontal
One Stack of
More Than 3
Storeys in Height
rnrn
Fixture hi ranch"'
3 Storeys in Height or
3 Intervals
_>^
Branch Interval
(1)
(2)
(3)
(4)
(5)
(6)
i 1 !
30
1
2
2
1
ii)
40
3
4
8
2
iii)
50
6
10
24
6
iv)
65
12
20
42
9
\i\
75
20
30
60
16
VI)
100
160
240
500
90
vii)
125
360
540
1 100
200
viii)
150
620
960
I 900
350
200
1 400
2 200
3 600
600
x)
250
2 500
3 800
5 600
1000
xi)
300
3 900
6 000
8 400
1 500
xii)
375
7 000
■ ■
~
~
uepenciing upon the probability of simultaneous use of appliances considering the frequency of use ana peaK aiscnarge rate.
Does not include branches uf the building sewer.
Table 26 Maximum Number of Fixture Units that can be Connected to
Building Drains and Sewers
(ClnuxP S S TS.n
SI
(1)
Diameter
mm
(2)
Maximum Number of Fixture Units that can be Connected to Any Portion 1 ' of the
n„'U! rv„_;_
DUUUillg UI dill UI 1IIC DUJUllllg
is o * — r> i;„_*
kJCTTCl iui uiauiciu
1/200
(3)
1/100
(4)
1/50
(5)
1/25
(6)
i)
ii)
iii)
iv)
V)
100
150
inn
250
300
2 500
3 900
180
700
i rnn
i uw
2 900
4 600
216
840
1 mn
3 300
5 600
250
1000
2 3QQ
4 200
6 700
11IC1UUCS UlcUiCllCS UI UIC UUllUHIg bCWCl.
500
UJ
Z
CO
ui
5
a
1800
1600
1400
t
***
w
laju
s
pm
800
600
400
w
<-
/
r
A
py
A
Pi
n
PI
CO
LU
400
UJ
5 200
-* 100
<
A
**
^
.~
.--
*-
/
/
s
^*
*~
**
*
r S
500 1000 1500 2000 2500 3000
FIXTURE UNITS
FOR SYSTEM PREDOMINANTLY FOR FLUSH VALVES
FOR SYSTEM PREDOMINANTLY FOR FLUSH TANKS
ESTIMATE CURVES
Frn 1 ^ Pfart Fi nw T nan Curves
>OOOQOOQOQC
FIXTURE UNITS
ENLARGE SCALE CURVES
*S
TsjATirkMAi ui tti nivin r'rknp of imf»i a
5.5.3.5.2.2 When flow occurs in drain piping, it should
not entirely fill the cross-section of the pipe under flow
condition. If the pipe were to flow full, pressure
fluctuations would occur which could possibly destroy
the seal of the traps within the building. Normally, the
sewer shall be designed for discharging the peak flow
as given in 5.5.3.5.1, flowing half-full with a minimum
self-cleansing velocity of 0.75 m/s. The approximate
gradients which give this velocity for the sizes of pipes
likely to be used in building drainage and the
corresponding discharges when following half-full are
given in Table 27.
5.5.3.5.2.3 In cases where it is practically not possible
to conform to the ruling gradients, a flatter gradient
may be used, but the minimum velocity in such cases
shall on no account be less than 0.61 m/s and adequate
flushing should be done.
NOTE — Where gradients are restricted, the practice of using a
pipe of larger diameter than that required by the normal flow,
in order to justify laying at a flatter gradient does not result in
increasing the velocity of flow, further this reduces the depth of
flow and thus for this reasons the above mentioned practice
should be discouraged.
5.5.3.5.2.4 On the other hand, it is undesirable to
employ gradients giving a velocity of flow greater than
2.4 m/s. Where it is unavoidable, cast iron pipes shall
be used. The approximate gradients, which give a
velocity of 2.4 m/s for pipes of various sizes and the
corresponding discharge when flowing half-full are
given in Table 27.
5.5.3.5.2.5 The discharge values corresponding to
nominal diameter and gradient given in Table 27 are
based on Manning's formula (n = 0.015).
NOTE — Subject to the minimum size of 100 mm, the sizes of
pipes shall be decided in relation to the estimated quantity of
flow and the available gradient.
Table 27 Different Dia Pipes Giving Velocity
and Corresponding Discharge at Minimum
and Maximum Gradient
(Clauses 5.5.3.5.2.2, 5.5.3.5.2.4, 5.5.3.5.2.5)
SI
Diameter
Minimum
Discharge
Maximum
Discharge
No.
Gradient
at the
Gradient
at the
(Velocity:
Minimum
(Velocity:
Maximum
0.75 m/s)
Gradient
2.4 m/s)
Gradient
mm
(mVmin)
(m 3 /min)
(1)
(2)
(3)
(4)
(5)
(6)
i)
100
1 in 57
0.18
1 in 5.6
0.59
ii)
150
1 in 100
0.42
1 in 9.7
1.32
iii)
200
1 in 145
0.73
linl4
2.40
iv)
230
1 in 175
0.93
1 in 17
2.98
v)
250
1 in 195
1.10
linl9
3.60
vi)
300
1 in 250
1.70
1 in 24.5
5.30
5.5.3.6 Drain appurtenances
5.5.3.6.1 Trap
All traps shall be protected against siphonage and back
pressure ensuring access to atmospheric air for air
circulation and preserving the trap seal in all conditions.
5.5.3.6.1.1 A trap may be formed as an integral trap
with the appliance during manufacture or may be a
separate fitting called an attached trap which may be
connected to the waste outlet of the appliance.
5.5.3.6.1.2 Traps should always be of a self-cleansing
pattern. A trap, which is not an integral part of an
appliance, should be directly attached to its outlet and
the pipe should be uniform throughout and have a
smooth surface,
5.5.3.6.1.3 The trap should have minimum size of
outlet/exit, same as that of largest waste inlet pipe.
5.5.3.6.1.4 Traps for use in domestic waste installations
and all other traps should be conveniently accessible
and provided with cleansing eyes or other means of
cleaning.
5.5.3.6.1.5 The minimum internal diameter for
sanitary appliances shall be as follows:
Sanitary Appliance
Minimum Internal
Diameter of
Waste Outlet
mm
Soil appliances
a) Indian and European type water- 100
closets
Bed pan washers and slop sinks 100
Urinal with integral traps 75
Stall urinals (with not more than 50
120 mm of channel drainage)
Lipped urinal small/large 40
Waste appliances
f) Drinking fountain 25
Wash basin 32
Bidets 32
Domestic sinks and baths 40
Shower bath trays 40
Domestic bath tubs 50
Hotel and canteen sinks 50
Floor traps (outlet diameter) 65
b)
c)
d)
e)
g)
h)
J)
k)
m)
n)
P)
5.5.3.6.2 Floor drains
All toilets/bathrooms in a building desirably should
be provided with floor drains to facilitate cleaning.
5.5.3.6.2.1 Floor drains shall connect into a trap so
constructed that it can be readily cleaned and of a size
to serve efficiently the purpose for which it is intended.
The trap shall be either accessible from the floor drain
or by a separate cleanout within the drain.
5.5.3.6.2.2 Floor drain also receives, waste piping
which does not connect to the sanitary system, known
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
59
as indirect waste. This discharge from an indirect waste
should be conveyed into a water supplied, trapped and
vented floor drain.
5.5.3.6.2.3 Floor drain should be provided in
mechanical equipment rooms, where pumps, boilers,
water chillers, heat exchangers and other air
conditioning equipments are periodically drained for
maintenance and repair. Boiler requires drain at safety
relief valve discharge.
5.5.3.6.2.4 Strategically floor drains are required to
be located in buildings with wet fire protection
sprinkler systems to drain water in case of activation
of sprinkler heads.
5.5.3.6.3 Cleanouts
The cleanout provides access to horizontal and vertical
lines and stacks to facilitate inspection and means to
remove obstructions common to all piping systems,
such as solid objects, greasy wastes, hair and the like.
5.5.3.6.3.1 Cleanouts in general should be gas and
water-tight, provide quick and easy plug removal,
allow ample space for rodding tools, have means of
adjustments to finished floor level, be attractive and
be designed to support whatever load is directed over
them.
5.5.3.6.3.2 Waste lines are normally laid beneath the
floor slab at a sufficient distance to provide adequate
back-fill over the joints. Cleanouts are then brought
up to floor level grade by pipe extension pieces.
5.5.3.6.3.3 The size of the cleanout within a building
should be the same size as the piping up to 100 mm.
For larger size piping 100 mm cleanouts are adequate
for their intended purpose.
5.5.3.6.3.4 Cleanouts ure suggested to be provided at
the following locations:
a) Inside the building at a point of exit, Y
junction branch or a trap.
b) At every change of direction greater than 45 ° .
c) At the base of all stacks.
d) At the horizontal header, receiving vertical
stacks and serving the purpose of offset
header.
5.5.4 Indirect Wastes
5.5.4.1 General
Waste, overflow and drain pipes from the following
types of equipment shall not be connected into any
drainage system directly to prevent backflow from the
drainage system into the equipment/installation:
a) Plumbing and kitchen appliances.
1) Underground or overhead water tanks.
2) Drinking water fountains.
3) Dishwashing sinks and culinary sinks
used for soaking and preparation of food.
4) Cooling counters for food and beverages.
5) Kitchen equipment for keeping food
warm.
6) Pressure drainage connections from
equipment.
b) Air conditioning, heating and other
mechanical equipments
1 ) Air handling equipment.
2) Cooling tower and other equipments.
3) Condensate lines from equipments.
4) Storage tanks.
5) Condensate lines.
6) Boiler blow down lines.
7) Steam trap drain lines.
c) Laboratories and other areas
1) Water stills.
2) Waste from laboratory in specified sinks.
3) Sterlizers and similar equipments.
4) Water purification equipments.
5.5.4.2 Indirect waste receptors
All plumbing fixtures or other receptors receiving the
discharge of indirect waste pipes shall be of such shape
and capacity as to prevent splashing or flooding and
shall be located where they are readily accessible for
inspection and cleaning.
5.5.4.3 Pressure drainage connections
Indirect waste connections shall be provided for drains,
overflows or relief vents from the water supply system,
and no piping or equipment carrying wastes or
producing wastes or other discharges under pressure
shall be directly connected to any part of the drainage
system.
The above shall not apply to any approved sump pump
or to any approved plumbing fixture discharging
pressurized waste or device when the Authority has
been satisfied that the drainage system has the capacity
to carry the waste from the pressurized discharge.
5.5.5 Special Wastes
5.5.5.1 General
Wastes having characteristics which may be detrimental
to the pipes in which it is disposed as well as to the
persons handling it. Such wastes used in a building
need to be specially identified and a suitable and safe
method of its disposal installed to ensure that the piping
system is not corroded nor the health and safety of the
occupants is affected in any way.
60
NATIONAL BUILDING CODE OF INDIA
Whenever the occupant or the user of any wastes is
unaware of the clangers of the consequences of
disposing the waste, he shall be made aware of the
dangers of his action along with providing suitable
warning and instruction for correct disposal be
provided to him.
Piping system for all special wastes should be separate
and independent for each type of waste and should not
be connected to the building drainage system. Other
applicable provisions for installation of soil and waste
pipe system shall be however be followed.
5.5.5.2 Laboratory wastes
A study of the possible chemical and corrosive and
toxic properties of wastes handled and disposed off in
a laboratory need to be ascertained in advance. The
relevant statutory rules and regulation regarding the
method of disposal of strong and objectionable wastes
shall be followed.
All sinks, receptacles, traps, pipes, fittings and joints
shall of materials resistant to the liquids disposed off
in the system.
In laboratories for educational, research and medical
institutions, handling mildly corrosive and toxic
wastes, they may be neutralized in chambers using
appropriate neutralizing agents. The chamber shall be
provided with chambers at inlet and outlet for
collecting samples of the incoming and outgoing waste
for monitoring its characteristics.
5.5.5.3 Infected wastes
Infected liquid wastes are generated in hospitals
from patient excreta; operation theatres; laboratories
testing samples of stools, urine, blood, flesh; etc
which shall not be disposed off into the drainage
system. Such waste shall be collected separately and
pre-treated before disposal into the building drainage
system.
Soiled and linen from infectious patients needs to be
collected from the respective areas of the hospital in
separate linen bins and pre-washed and sterilized in
the laundry before final wash in the hospital laundry.
Liquid wastes from the washing operations shall be
neutralized to prevent any cross contamination before
disposal in the building's drainage system.
5.5.5.4 Research laboratory wastes
Research laboratories conducting research in all areas
of science and technology, for example chemical
industry, pharmacy, metallurgy, bio-sciences,
agriculture, atomic energy, medicine, etc, shall follow
the established procedures laid down by statutory
bodies to handle, treat and dispose wastes which are
highly toxic, corrosive, infectious, inflammable,
explosive and having bacterial cultures, complex
organic and inorganic chemicals. Such wastes shall
not be disposed off in a building drainage system or
the city sewerage system unless they are pre-treated
and meet the disposal criteria in accordance with the
relevant rules/regulations.
5.5.6 Grease Traps
Oil and grease is found in wastes generated from
kitchens in hotels, industrial canteens, restaurant,
butcheries, some laboratories and manufacturing units
having a high content of oil and greases in their final
waste.
Waste exceeding temperature of 60° C should not be
allowed in the grease trap. When so encountered it may
be allowed to cool in a holding chamber before entering
the grease trap.
Oil and greases tend to solidify as they cool within the
drainage system. The solidified matter clogs the drains
and the other matter in the waste stick to it due to the
adhesion properties of the grease. Oil and greases are
lighter than water and tend to float on the top of the
waste water.
Grease traps shall be installed in building having the
above types of wastes. In principle the grease laden
water is allowed to retain in a grease trap which enables
any solids to be settled or separated for manual
disposal. The retention time allows the incoming waste
to cool and allow the grease to solidify. The clear waste
is then allowed to discharge into the building's drainage
system.
5.5.7 Oil Interceptors
Oils and lubricants are found in wastes from vehicle
service stations, workshops manufacturing units whose
waste may contain high content of oils. Oils, for
example, petroleum, kerosene and diesel used as fuel,
cooking, lubricant oils and similar liquids are lighter
than water and thus float on water in a pipe line or in a
chamber when stored. Such oils have a low ignition
point and are prone to catch fire if exposed to any flame
or a spark and may cause explosion inside or outside
the drainage system. The flames from such a fire spread
rapidly if not confined or prevented at the possible
source. Lighter oils and lubricants are removed
from the system by passing them through an oil
interceptor/petrol gully. They are chambers in various
compartments which allow the solids to settle and allow
the oils to float to the top. The oil is then decanted in
separate containers for disposal in an approved manner.
The oil free waste collected from the bottom of the
chamber is disposed in the building drainage system.
5.5.8 Radioactive Waste
Scientific research institutions, hospital and many types
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
61
of manufacturing processes use radio active material
in form of radio isotopes and other radio active sources
for their activities. Manufacture, sale, use and disposal
of radio active material is regulated by the statutory
rules and regulation. Proposal for usage and disposal
of radio active materials shall be done in consultation
with and prior permission of the Authority by the users
of the materials. No radio active material shall be
disposed off in any building drainage system without
the authorization of the Authority.
5.5.9 Special Situations of Waste Water Disposal
Buildings may generate uncontaminated waste water
from various sources continuously, intermittently or
in large volumes for a short time, for example,
emptying any water tanks or pools, testing fire and
water lines for flow conditions, etc. Connections from
all such sources shall be made to the building drainage
system indirectly through a trap. It should be ensured
in advance that the building drain or a sump with a
pump has the capacity to receive to rate of flow. In
case the capacity is less the rate of discharge from the
appliances should be regulated to meet the capacity of
the disposal. Under no circumstances shall any waste
water described above shall be disposed off in any
storm water drains.
5.5.10 Manholes
5.5.10.1 General
A manhole or inspection chamber shall be capable of
sustaining the loads which may be imposed on it,
exclude sub-soil water and be water-tight. The size
of the chamber should be sufficient to permit ready
access to the drain or sewer for inspection, cleaning
and rodding and should have a removable cover of
adequate strength, constructed of suitable and durable
material. Where the depth of the chamber so requires,
access rungs, step irons, ladders or other means should
be provided to ensure safe access to the level of the
drain or sewer. If the chamber contains an open
channel, benching should be provided having a
smooth finish and formed so as to allow the foul
matter to flow towards the pipe and also ensure a safe
foothold.
No manhole or inspection chamber shall be permitted
inside a building or in any passage therein. Further,
ventilating covers shall not be used for domestic drains.
At every change of alignment, gradient or diameter of
a drain, there shall be a manhole or inspection chamber.
Bends and junctions in the drains shall be grouped
together in manholes as far as possible.
5.5.10.2 Spacing of manholes
The spacing of manholes for a given pipe size should
be as follows:
Pipe Diameter
Spacing of Manhole
mm
m
a) Up to 300
45
b) 301 to 500
75
c) 501 to 900
90
d) Beyond 900
Spacing shall depend upon local
condition and shall be gotten
approved by the Authority
Where the diameter of a drain is increased, the crown
of the pipes shall be fixed at the same level and the
necessary slope given in the invert of the manhole
chamber. In exceptional cases and where unavoidable,
the crown of the branch sewer may be fixed at a lower
level, but in such cases the peak flow level of the two
sewers shall be kept the same.
5.5.10.3 Size of manhole
The manhole or chamber shall be of such size as will
allow necessary examination or clearance of drains. The
size of manhole shall be adjusted to take into account
any increase in the number of entries into the chamber.
5.5.10.3.1 Manholes may be rectangular, arch or circular
type. The minimum internal size of manholes, chambers
(between faces of masonry) shall be as follows:
a) Rectangular Manholes
1) For depths less than 900 mm x
0.90 m 800 mm
2) For depths from 0.90 m 1 200 mm x
and up to 2.5 m 900 mm
b) Arch Type Manholes
a) For depths of 2.5 m and 1 400 mm x
above 900 mm
NOTE — The width of manhole chamber shall be suitably
increased more than 900 mm on bends, junctions or pipes
with diameter greater than 450 mm so that benching width
in either side of channel is minimum 200 mm.
c) Circular Manholes
1) For depths above 0.90 m 900 mm
and upto 1.65 m diameter
2) For depths above 1.65 m 1 200 mm
and upto 2.30 m diameter
3) For depths above 2.30 m 1 500 mm
and upto 9.00 m diameter
4) For depths above 9.00 m 1 800 mm
and upto 14.00 m diameter
NOTES
1 In adopting the above sizes of chambers, it should
be ensured that these sizes accord with full or half
bricks with standard thickness of mortar joints so as
to avoid wasteful cutting of bricks.
2 The sizes of the chambers may be adjusted to suit
the availability of local building materials and
economics of construction.
3 The access shaft shall be corbelled inwards on
three sides at the top to reduce its size to that of the
62
NATIONAL BUILDING CODE OF INDIA
cover frame to be fitted or alternatively the access
shaft shall be covered over by a reinforced concrete
slab of suitable dimensions with an opening for
manhole cover and frame.
5.5.10.4 Construction
5.5.10.4.1 Excavation
The manhole shall be excavated true to dimensions and
levels as shown on the plan. The excavation of deep
manholes shall be accompanied with safety measures
like timbering, staging, etc. In areas where necessary,
appropriate measures for dewatering should be made.
5.5.10.4.2 Bed Concrete
The manhole shall be built on a bed of concrete 1:4:8
(1 cement: 4 coarse sand: 8 graded stone aggregate
40 mm nominal size). The thickness of bed concrete
shall be at least 150 mm for manholes upto 0.9 m in
depth, at least 200 mm for manholes from 0.90 m upto
2.5 m in depth and at least 300 mm for manholes of
greater depth, unless the structural design demands
higher thickness.
This thickness may be verified considering the weight
of wall, cover, the wheel loads, impact of traffic which
are transmitted through cover and the shaft walls and
for water pressure, if any. In case of weak soil, special
foundation as suitable shall be provided
5.5.10.4.3 Brickwork
The thickness of walls shall be designed depending
upon its shape and taking onto account all loads coming
over it, including earth pressure and water pressure.
Generally the brickwork shall be with first class bricks
in cement mortar 1:5 (1 cement: 5 coarse sand). All
brickwork in manhole chambers and shafts shall be
carefully built in English Bond, the jointing faces of
each brick being well "buttered" with cement mortar
before laying, so as to ensure a full joint. The
construction of walls in brickwork shall be done in
accordance with good practice [9-1(26)].
For various depths the recommended thickness of wall
may be as follows:
Depth of the Chamber Thickness of Wall
a) Upto 2.25 m 200 mm (one brick
length)
b) From Z25 m upto 3.0 m 300 mm (one and half
brick length)
c) From 3.00 m upto 5.0 m 400 mm (two brick
length)
d) From 5.00 m upto 9.0 m 500 mm (two and
half brick length)
e) Above 9.00 m 600 mm (three brick
length)
The actual thickness in any case shall be calculated on
the basis of engineering design. Typical sections of
the manholes are illustrated in Fig. 14, 15 and 16.
NOTES
1 Rich mix of cement mortar, not weaker than 1:3, should be
used in brick masonry, where sub-soil water conditions are
encountered.
2 For arched type of manholes, the brick masonry in arches
and arching over pipes shall be in cement mortar 1:3.
5.5.10.4.4 Plastering
The wall shall be plastered (15 mm, Mm) both inside
and outside within cement mortar 1:3 and finished
smooth with a coat of neat cement. Where sub-soil
water conditions exit, a richer mix may be used and it
shall further waterproofed with addition of approved
waterproofing compound in a quantity as per
manufacturer specifications.
All manholes shall be so constructed as to be water-
tight under test.
All angles shall be rounded to 15 mm radius and all
rendered internal surface shall have hard impervious
finish obtained using a steel trowel.
5.5.10.4.5 Channels and benching
These shall be semi-circular in the bottom half and of
diameter equal to that of the sewer. Above the
horizontal diameter, the sides shall be extended
vertically 50 mm above the crown of sewer pipe and
the top edge shall be suitably rounded off. The branch
channels shall also be similarly constructed with
respect to the benching, but at their junction with the
main channel an appropriate fall, if required suitably
rounded off in the direction of flow in the main channel
shall be given.
The channel/drain and benching at the bottom of the
chamber shall be done in cement concrete 1:2:4 and
subsequently plastered with cement mortar of 1:2
proportion or weaker cement mortar with a suitable
waterproofing compound and finished smooth, to the
grade (where required). The benching at the sides shall
be carried up in such a manner as to provide no
lodgment for any splashing in case of accidental
flooding of the chamber. ,.
Channels shall be rendered smooth and benchings shall
have slopes towards the channel.
5.5.10.4.6 Rungs
Rungs shall be provided in all manholes over 0.8 m in
depth and shall be of preferably of cast iron and of
suitable dimensions, conforming to accepted standards
[9-1(27)]. These rungs may be set staggered in two
vertical rungs which may be 300 mm apart horizontally
as well as vertically and shall project a minimum of
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
63
2
>
H
s
w
|
2
o
n
g
M
O
2
6B
SECTIONAL PLAN AT ZZ
50cmDIA
H^/W z
DEPTH OF
MANHOLE
RING ARCH
RENDERING WITH
CEMENT MORTAR 1 : 2
DETAIL OF BENCHING
W4&1 C2JC^3[^I3 BE E^
SECTION XX SECTION YY
Fig. 14 Detail of Manhole (Depth less than 0.90 m)
RENDERING WITH
CEMENT MORTAR 1 : 2
T
DETAIL OF BENCHING
SECTIONAL PLAN AT ZZ
50
SECTION XX SECTION YY
All dimensions in centimetres.
Fig. 15 Detail of Manhole (Depth from 0.9 m and up to 2.5 m)
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
65
RENDERING WITH
CEMENT MORTAR 1 : 2
DETAIL OF BENCHING
50
DEPTH OF
MANHOLE
SECTION XX
SECTION YY
All dimensions in centimetres.
Fig. 16 Detail of Manhole (Depth 2.5 m and Above)
100 mm beyond the finished surface if the manhole
wall. The top rung shall be 450 mm below the manhole
cover and the lowest not more than 300 mm above the
benching.
5.5.10.4.7 Manhole covers and frames
The size of manhole covers shall be such that there
shall be a clear opening of at least 500 mm in diameter
for manholes exceeding 0.90 m in depth. The manhole
covers and frames are used they shall conform to
accepted standards [9-1(28)].
The frame of manhole shall be firmly embedded to
concrete alignment and level in plain concrete on the
top of masonry.
5.5.10.5 Drop manhole
Where it is uneconomic or impracticable to arrange the
connection within 600 mm height above the invert of
66
NATIONAL BUILDING CODE OF INDIA
the manholes, the connection shall be made by
constructing a vertical shaft outside the manhole
chamber, as shown in Fig. 17. If the difference in level
between the incoming drain and the sewer does not
exceed 600 mm, and there is sufficient room in the
manhole, the connecting pipe may be directly brought
through the manhole wall and the fall accommodated
by constructing a ramp in the benching of the manhole.
For detailed information regarding manholes in
sewerage system, reference may be made to good
practice [9-1(29)].
SECTIONAL PLAN AT 22
50
SECTION XX
SECTION YY
NOTE — Wall thickness have been indicated in brick length to provide for use of modular bricks or traditional
bricks. In the Fig. B = one brick length, 1.55 = one and a half brick length etc.
All dimensions in centimetres.
Fig. 17 Drop Manhole
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
67
5.5.11 Storm Water Drainage
5.5.11.1 General
The object of storm water drainage is to collect and
carry, the rain-water collected within the premises of
the building, for suitable disposal.
5.5.11.2 Design factors
Estimate of the quantity that reaches the storm water
drain depends on the following factors:
a) Type of soil and its absorption capacity
determined by its soil group.
b) Ground slope and the time in which the area
is drained.
c) Intensity of the rainfall for a design period.
d) Duration of the rain/storm.
5.5.11.2.1 Imperviousness
The soil conditions and the ground slope determine
the impermeability factor. Impermeability factor is the
proportion of the total rainfall received on the surface
which will be discharging into the a storm water drain
after allowing for initial abstraction (in local pond and
lakes), ground absorption by evaporation, vegetation
and other losses. The net flow reaching the storm water
drain is called runoff.
The percentage of imperviousness of the drainage area
may be obtained from available data for a particular
area. In the absence of such data, the following values
may serve as a guide:
Type of area Imperviousness factor
(percent)
Commercial and industrial areas 70-90
Residential areas (high density) 60-75
Residential areas (low density) 35-60
Parks and underdeveloped areas 10-20
5.5.11.2.2 Terrain modelling
Areas planned for urbanization from agricultural land,
forest or low grade land for example, low lying areas
prone to flooding, marshy or abandoned quarries, etc
need detailed and careful consideration with respect
to its drainage. A detailed contour survey shall be
carried out not only with respect to the site but also
the surrounding areas to verify the quantity/area
contributing runoff, presence of any low lying and
natural water body acting as holding pond or any
natural drain passing through the area and beyond
whose filling up or diversion may cause water logging
problem on the site or to the surrounding areas.
The planning of the area should ensure that:
a) All areas become self draining by gravity with
respect to the high flood level of the area or
the drainage channels passing which ever is
higher.
b) As far as possible, natural drainage pattern
with respect to the whole area be maintained
except when low lying areas need to be filled
up for grading purposes.
c) The drainage in the area shall be planned in
accordance with the natural slopes.
d) Levels of the main highway or road connecting
to the property shall be determined to ensure
proper drainage and protection of the site.
The formation levels of the entire area shall be prepared
to determine proposed formation levels by preparing
a terrain model which will show the proposed the site
contours, ground and road levels and connections to
all services including storm water disposal system.
5.5.11.2.3 Design frequency
Storm water drainage system for an urbanized area is
planned on the basis of the design frequency of the
storm which shall be determined by the designer.
Frequency is the period in which the selected design
intensity recurs in a given period of time in years.
5.5.11.2.4 Time of concentration
Time of concentration is the time required for the rain-
water to flow to reach the farthest point of the drainage
system or the outfall under consideration. Time of
concentration is equal to the inlet time plus the time
required for the flow to reach the main or branch drain.
The inlet time is the time dependent on the distance of
the farthest point in the drainage area to the inlet of
the manhole and the surface slopes, etc and will vary
between 5 min to 30 min.
In highly developed sections for example with
impervious surfaces it may be as low as 3 min or lower
(with good slopes) as in building terraces and paved
areas. Correspondingly the design intensity for the
drainage for such areas will be much higher. Rain-
water pipes have to be designed for an intensity for a
very low time of concentration.
5.5.11.2.5 Natural infiltration
In planning any area with buildings, layout with paved
and non-permeable surfaces, care should be taken to
allow maximum discharge of the rain-water to flow
directly or indirectly to permeate into the ground for
enabling the ground water to be recharged. Some of
the techniques which allow infiltration that may be
considered are:
a) Use of brick paved open jointed storm water
drains.
b) Providing bore holes in the storm water drains.
68
NATIONAL BUILDING CODE OF INDIA
c) Using paving tiles with open joints which
enable water to percolates as it flows on it.
5.5.11.3 Combined system
A combined system of drainage is one which carries
the sewerage as well as the runoff from the storm water
drainage. Relevant applicable statutory rules/
regulations may not allow such system in new areas
and the sewerage and the storm water drainage have
to be separate and independent of each other. Such
systems are however existing in many old cities and
the storm water may have to be discharged into the
combined drainage system.
Where levels do not permit for connection to a public
storm water drain, storm water from courtyards of
buildings may be connected to the public sewer,
provided it is designed to or has the capacity to convey
combined discharge. In such cases, the surface water
shall be admitted to the soil sewer through trapped
gullies in order to prevent the escape of foul air.
5.5.11.4 Discharging into a watercourse
It may often be convenient to discharge surface water
to a nearby stream or a watercourse. The invert level
of the outfall shall be about the same as the normal
water level in the watercourse or ideally should be
above the highest flood level of the watercourse. The
out-fall shall be protected against floating debris by a
screen.
5.5.11.5 Discharge to a public storm water drain
Where it is necessary to connect the discharge
rainwater into a public storm water drain, such drains
shall be designed for the intensity of rain based on
local conditions, but in no case shall they be designed
for intensity of rainfall of less than 50 mm/hour. Rain-
water from each building plot shall be connected to
the storm water drainage through a separate pipe or an
open public drain directly. No trap shall be installed
before the connection.
5.5.11.6 Rain-water pipes for roof drainage
5.5.11.6.1 The roofs of a building shall be so
constructed or framed as to permit effectual drainage
of the rain-water therefrom by means of a sufficient
number of rain-water pipes of adequate size so
arranged, jointed and fixed as to ensure that the rain-
water is carried away from the building without causing
dampness in any part of the walls or foundations of
the building or those of an adjacent building.
5.5.11.6.2 The rain-water pipes shall be fixed to the
outside of the external walls of the building or in
recesses or chases cut or formed in such external wall
or in such other manner as may be approved by the
Authority.
5.5.11.6.3 Rain-water pipes conveying rain- water shall
discharge directly or by means of a channel into or
over an inlet to a surface drain or shall discharge freely
in a compound, drained to surface drain but in no case
shall it discharge directly into any closed drain.
5.5.11.6.4 Whenever it is not possible to discharge a
rain-water pipe into or over an inlet to a surface drain
or in a compound or in a street drain within 30 m from
the boundary of the premises, such rain-water pipe shall
discharge into a gully trap which shall be connected
with the street drain for storm water and such a gully-
trap shall have a screen and a silt catcher incorporated
in its design.
5.5.11.6.5 If such streets drain is not available within
30 m of the boundary of the premises, a rain-water
pipe may discharge directly into the kerb drain and
shall be taken through a pipe outlet across the foot
path, if any, without obstructing the path.
5.5.11.6.6 A rain water pipe shall not discharge into
or connect with any soil pipe or its ventilating pipe or
any waste pipe or its ventilating pipe nor shall it
discharge into a sewer unless specifically permitted to
do so by the Authority, in which case such discharge
into a sewer shall be intercepted by means of a gully
trap.
5.5.11.6.7 Rain-water pipes shall be constructed of
cast iron, PVC, asbestos cement, galvanized sheet or
other equally suitable material and shall be securely
fixed.
5.5.11.6.8 The factors that decide the quantity of rain
water entering are:
a) Intensity of rainfall, and
b) Time of concentration selected for rain-water
pipe.
A bell mouth inlet at the roof surface is found to give
better drainage effect, provided proper slopes are given
to the roof surface. The spacing of rain-water pipes
depends on the locations available for the down takes
and the area which each pipe serves. The spacing will
also be determined by the amount of slopes that can
be given to the roof. The recommended slopes for the
flat roofs with smooth finish would be 1 : 150 to 1 : 133,
with rough stone/tiles 1:100 and for gravel set in
cement or losely packed concrete finish 1:75 to 1:66.
The effective strainer area should preferably be 1.5 to
2 times the area of pipe to which it connects to
considerably enhance the capacity of rain water pipes.
The rain water pipes of cast iron (coefficient of
roughness 0.013) shall normally be sized on the basis
of roof areas according to Table 28. The vertical down
take rain-water pipes, having a bell mouth inlet on the
roof surface with effective cross-sectional area of
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
69
grating 1.5 to 2 times the rain-water pipe area, may be
designed by considering the outlet pipe as weir.
For full circumference of pipe acting as weir, the roof
area (RA) for drainage may be worked out by using
RA = 0.084 x <f ll II
where
d - Pipe diameter; mm
/ - Intensity of rainfall (mm/h).
Table 28 Sizing of Rain- Water Pipes for
Roof Drainage
{Clause 5.5.11.6.8)
Diaof
Pipe
(mm)
50
65
Average Rate of Rainfall
(mm/h)
50
13.4
24.1
75
8.9
16.0
125
100
Roof Area (m 2 )
6.6
12.0
5.3
9.6
150
4.4
8.0
200
3.3
6.0
75 40.8 27.0 20.4 16.3 13.6 10.2
100 85.4 57.0 42.7 34.2 28.5 21.3
125 159.71 106.73 80.50 64.3 53.5 40.0
150 249.60 166.82 125.27 100.00 83.6 62.7
NOTE — For rain-water pipes of other materials, the roof
areas shall be multiplied by (0.013/coefficient of roughness of
surface of that material).
5.5.11.6.9 The storm water may be led off in a suitable
open drain to a watercourse. The open drain, if not a
pucca masonry through out, shall be so at least where
there is either a change in direction or gradient.
5.5.12 Rain-water Harvesting
5.5.12.1 General
To supplement the ever growing shortage of protected,
pure and safe water supply for human consumption
rainwater is an ideal source which can be conserved
and used in a useful manner by the people. The amount
of rainfall available varies from region to region. Each
area has to develop its own method and system to
conserve, store and use it to suit its requirements and
local conditions. There are several methods by which
rain-water can be stored, used and conserved. Each
system depends on the amount of precipitation, the
period in which the rainfall occurs in a year and the
physical infrastructure for example, space available to
store the water, etc.
There are several techniques available for catching and
storing the rain-water. Most of the techniques are
applicable for large open areas, farms, sloping grounds
etc, with a low population base. Two major systems that
are ideal for urban and semi-urban developed areas are:
a) Artificial ground water recharge, and
b) Roof top rain-water harvesting.
5.5.12.2 Artificial ground water recharge
With increase in the impermeable surfaces in modern
built up areas, a large quantity of water normally
percolating into the ground runs off to the natural
drains and into the rivers causing increased runoff
and flooding of downstream areas as it also deprives
the original catchment area of the natural percolation
that would have recharged the area in the normal
course if the ground was in its natural condition for
example a farm, open ground, forest, etc. It is
therefore essential to catch the runoff and use it for
augmentation of ground water reservoir by modifying
the natural movement of surface water by recharging
it by artificial means for example, construction of
recharge structures (see Fig. 18). The main objectives
achieved may be:
a) Enhancement of sustainable yield in areas
where there is over development and
depletion of the aquifers.
b) Conservation and storage of excess surface
water in the aquifers.
c) Improve the quality of the existing ground
water through dilution.
d) Remove bacteriological and suspended
impurities during the surface water transition
within the sub-soil.
e) Maintain the natural balance of the ground
water and its usage as the rain-water is a
renewable supply source. A well managed and
controlled tapping of the aquifers will provide
constant, dependable and safe water supply.
In planning and designing the ground water recharge
structures following should be taken into consideration:
a) Annual rainfall (for estimating approx rain-
water recharge per year).
b) Peak intensity and duration of each storm.
c) Type of soil and sub-soil conditions and their
permeability factor.
d) Ground slopes and runoff which cannot be
caught. *
e) Location of recjiarge structures and its
overflow outfall.
f) Rainwater measuring devices for finding the
flow of water in the system.
For artificial recharge to ground water, Guidelines
for Artificial Recharge to Ground Water (under
preparation) may be referred.
5.5.12.3 Rooftop rain-water harvesting
5.5.12.3.1 Harvesting in regular rainfall areas
In areas having rainfall over a large period in a year
70
NATIONAL BUILDING CODE OF INDIA
INLET
COARSE SAND
1.5 TO 2mm
GRAVEL 5 TO 10 mm SIZE
BOULDER 5 TO 20 mm SIZE
3 mm SLOT SIZE
-BALL PLUG
Fig. 18 Artificial Ground Water Recharge Structure
for example, in hilly areas and coastal regions,
constant and regular rainfall can be usefully harvested
and stored in suitable water tanks. Water is collected
through roof gutters and down take pipes. Provision
should be made to divert the first rainfall after a dry
spell so that any dust, soot, leaves etc, are drained
away before the water is collected into the water tank.
The capacity of the water tank should be enough for
storing water required for consumption between two
dry spells. The water tank shall be located in a well
protected area and should not be exposed to any
hazards of water contamination from any other
sources. The water shall be chlorinated using chlorine
tablets or solution to maintain a residual chlorine of
approximately 1 mg/1. The tank must have an
overflow leading to a natural water courses or to any
additional tanks (see Table 29).
5.5.12.3.2 Harvesting in urban areas
In urban areas with the rainfall limited during the
monsoon period (usually from 15-90 days) roof top
rain-water cannot be stored and used as mentioned
above and is best used for recharging the ground water.
For individual properties and plots the roof top rain-
water should be diverted to existing open or abandoned
tubewells. In a well planned building complex the
system should be laid out so that the runoff is
discharged in bore-wells as per designs specified by
the Central Ground Water Board of the Government
of India.
For roof top rain water harvesting in hilly areas
reference may be made to good practice [9-1(30)].
5.5.12.4 Care to taken in rain-water harvesting
Water conservation technique discussed above shall be
constructed with due care taking following precautions:
a) No sewage or waste water should be admitted
into the system.
b) No waste water from areas likely to have oil,
grease or other pollutants should be connected
to the system.
c) Each structure/well shall have an inlet
chamber with a silt trap to prevent any silt
from finding its way into the sub-soil water.
d) The wells should be terminated at least 5 m
above the natural static sub-soil water at its
highest level so that the incoming flow passes
through the natural ground condition and
prevents contamination hazards.
e) No recharge structure or a well shall be used
for drawing water for any purpose.
5.5.13 Sub-soil Water Drainage
5.5.13.1 General
Sub-soil water is that portion of the rainfall which is
absorbed into the ground.
The drainage of sub-soil water may be necessary for
the following reasons:
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
71
Table 29 Rainwater Available from Roof Top Harvesting
(Clause 5.5.12.3.1)
Rain — »
100
200
300
400
500
600
700
800
900
1000
1 100
1200
1300
1400
1500
1600
1700 :
1800 :
1900 2000
Fall in
mm
Roof
Top Area
Harvested Water from Roof Tops m
rrT
i
20
(80 percent of gross precipitation)
2
3
5
6
8
10
11
13
14
16
18
19
21
22
24
26
27
29
30
32
30
2
5
7
10
12
14
17
19
22
24
26
29
31
34
36
38
41
43
46
48
40
3
6
10
13
16
19
22
26
29
32
35
38
42
45
48
51
54
58
61
64
50
4
8
12
16
20
24
28
32
36
40
44
48
52
56
60
64
68
72
76
80
60
5
10
14
19
24
29
34
38
43
48
53
58
62
67
72
77
82
86
91
96
70
6
11
17
22
28
34
39
45
50
56
62
67
73
78
84
90
95
101
106
112
80
6
13
19
26
32
38
45
51
58
64
70
77
83
90
96
102
109
115
122
128
90
7
14
22
29
36
43
50
58
65
72
79
86
94
101
108
115
122
130
137
144
100
8
16
24
32
40
48
56
64
72
80
88
96
104
112
120
128
136
144
152
160
110
9
18
26
35
44
53
62
70
79
88
97
106
114
123
132
141
150
158
167
176
120
10
19
29
38
48
58
67
77
86
96
106
115
125
134
144
154
163
173
182
192
130
10
21
31
42
52
62
73
83
94
104
114
125
135
146
156
166
177
187
198
208
140
11
22
34
45
56
67
78
90
101
112
123
134
146
157
168
179
190
202
213
224
150
12
24
36
48
60
72
84
96
108
120
132
144
156
168
180
192
204
216
228
240
200
16
32
48
64
80
96
112
128
144
160
176
192
208
224
240
256
272
288
304
320
250
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
320
340
360
380
400
300
24
48
72
96
120
144
168
192
216
240
264
288
312
336
360
384
408
432
456
480
400
32
64
96
128
160
192
224
256
288
320
352
384
416
448
480
512
544
576
608
640
500
40
80
120
160
200
240
280
320
360
400
440
480
520
560
600
640
680
720
760
800
1000
80
160
240
320
400
480
560
640
720
800
880
960
1040
1 120
1200
1280
1360
1440
1520
1600
2 000
160
320
480
640
800
960 1 120 1 280 1440
1600
1 760
1 920 2 080 2 240 2 400 2 560 2 720 2 880 3 040 3 200
3 000
240
480
720
960 1 200 1 440 1 680 1 920 2 160 2 400 2 640 2 880 3 120 3 360 3 600 3 840 4 080 4 320 4 560 4 800
a) to increase the stability of the surface;
b) to avoid surface flooding;
c) to alleviate or to avoid causing dampness in
the building, especially in the cellars;
d) to reduce the humidity in the immediate
vicinity of the building; and
e) to increase the workability of the soil.
5.5.13.2 Depth of water table
The standing level of the sub-soil water will vary with
the season, the amount of rainfall and the proximity and
level of drainage channels. Information regarding this
level may be obtained by means of boreholes or trial
pits, preferably the latter. It is desirable though not
always practicable to ascertain the level of the standing
water over a considerable period so as to enable the
seasonal variations to be recorded and in particular the
high water level. The direction of flow of the sub-soil
water may usually be judged by the general inclination
of the land surface and the main lines of the subsoil
drains shall follow the natural falls, wherever possible.
5.5.13.3 Precautions
Sub-soil drains shall be so sited as not to endanger the
stability of the buildings or earthwork. In some portions
of the drain, it may be necessary to use non-porous
jointed pipes.
5.5.13.3.1 No field pipe shall be laid in such a manner
or in such a position as to communicate directly with
any drain constructed or adopted to be used for
conveying sewage, except where absolutely
unavoidable and in such case a suitable efficient trap
shall be provided between sub-soil drain and such sewer.
5.5.13.4 Systems of sub- soil drainage
Clay or concrete porous field drain pipes may be used
and shall be laid in one of the following ways {see
also Fig. 19):
a) Natural — The pipes are laid to follow the
natural depressions or valleys of the site;
branches discharge into the main as tributaries
do into a river.
b) Herringbone — The system consists of a
number of drains into which discharges from
both sides smaller subsidiary branch drains
parallel to each other, but an angle to the
mains forming a series of herringbone pattern.
Normally these branch drains should not
exceed 30 m in length.
c) Grid — A main or mains drain is laid to the
boundaries if the site into which subsidiary
branches discharge from one side only.
d) Fan-Shaper — The drains are laid converging
to a single outlet at one point on the boundary
72
NATIONAL BUILDING CODE OF INDIA
BUILDING
C) GRID IRON E) M0ST 0F CUT Qpp
Fig. 19 Details of Sub-soil Drainage System
of a site, without the use of main or collecting
drains.
e) Moat or cut-off system — This system
consists of drains laid on one or more sides
of a building to intercept the flow of subsoil
water and carry it away, thereby protecting
the foundations of a building.
The choice of one or more of these systems will
naturally depend on the local conditions of the site.
For building sites, the mains shall be not less than
75 mm in diameter and the branches not less than
65 mm in diameter and the branches not less than
65 mm in diameter but normal practice tends towards
the use of 100 mm and 75 mm respectively. The pipes
shall generally be laid at 600 to 900 mm depth, or to
such a depth to which it is desirable to lower the water-
table and the gradients are determined rather by the
fall of the land than by considerations of self-cleansing
velocity. The connection of the subsidiary drain to the
main drain is best made by means of a clayware or
concrete junction pipe. The outlet of a sub-soil system
may discharge into a soakaway or through a catch pit
into the nearest ditch or watercourse. Where these are
not available, the sub-soil drains may be connected,
with the approval of the Authority, through an
intercepting trap to the surface water drainage system.
NOTE — Care shall be taken that there is no backflow from
sub-surface drains during heavy rains.
5.5.14 Waste Disposal Systems in High Altitudes and
or Sub-zero Temperature Regions
5,5.14.1 In general, all the cases to be exercised
regarding water supply systems shall also be applicable
in the case of waste disposal systems shall also be
applicable in the case of waste disposal systems. The
biological and chemical reduction of organic material
proceeds slowly under low temperature conditions,
consequently affecting the waste disposal systems. The
waste disposal methods given in 5.5.14.2, 5.5.14,3
and 5.5.14.4 shall be used only where it is not practical
to install water carriage system.
5.5.14.2 Box and can system
Where box and can systems are employed, adequate
arrangements shall be made for the cleaning and
disinfection of the can after it is emptied of its contents.
The excrement from the can shall be disposed of by
burial in isolated spots far from habitation or by
incineration, where feasible. The can shall be fitted
with a tight fitting lid for use when it is carried for
emptying.
5.5.14.3 Trench or pit latrines
Trench or pit latrines shall be used only where soil
and sub-soil conditions favour their use. Whenever
they are used, they shall not be closer than 18 m from
any source of drinking water, such as well, to eliminate
the possibility of bacterial pollution of water.
5.5.14.4 Chemical toilets
For the successful functioning of chemical toilets, they
shall preferably be installed in heated rooms or
enclosures.
NOTE — Chemical toilet essentially consists of small cylindrical
tanks with a water-closet seat for the use of 8 to 10 persons. A
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
73
ventilation pipe is fitted to the seat. A strong solution of caustic
soda is used as a disinfectant. It kills bacteria, liquefies the solids
and thus checks the decomposition of organic matter. The tank
is provided with a drain plug for which liquid runs to a soak pit
at the time of disposal.
5.5.14.5 Water-borne sanitation systems
Water-borne sanitation systems shall be used,
where practicable. Sanitation systems for the
collection of sewage should be constructed in such a
manner that maximum heat is retained by insulation,
if necessary.
5.5.14.5.1 Sewerage laying
Under normal circumstances, sewers shall be laid
below the frost line. Manholes shall be made of air-
tight construction so as to prevent the cold air from
gaining access inside and freezing the contents. The
trenches for sewers shall be loosely filled with earth
after laying sewers, since loose soil is a better insulator
than compacted soil. Consequently, sewers laid under
traffic ways and other places where soil compaction
may be expected are required to be given adequate
insulation. Where feasible, sewers shall be so located
that the trench line is not in shadow, when the sun is
shining. Concrete, cast iron and stoneware pipes
conduct heat relatively rapidly and as such should be
adequately insulated.
5.5.14.5.2 Septic tanks
Septic tanks can function only when it can be ensured
that the contents inside these do not freeze at low
temperature. For this purpose, the septic tanks shall
be located well below the frost line. The location of
manhole openings shall be marked by staves. Fencing
around the septic tanks shall be provided for
discouraging traffic over them. As the rate of biological
activity is reduced by 50 percent for every 10°C fall in
temperature, the capacity of septic tanks shall be
increased by 100 percent for operation at 10°C over
that for operation at 20°C.
5.5.14.5.3 Seepage pits
Seepage pits can function only when the soil and sub-
soil conditions are favourable. Frozen soil extending
to a great depth would preclude the use of such disposal
devices in view of the lower water absorption capacity.
The discharge of effluent should be made below the
frost line.
5.5.14.5.4 Sewage treatment plants
Suitable design modifications for sedimentation,
chemical and biological processes shall be applied to
sewage treatment plants for satisfactory functioning.
NOTE — Lavatories and bathrooms shall be kept heated to avoid
freezing of water inside traps and flushing cisterns.
5.6 Construction Relating to Conveyance of
Sanitary Wastes
5.6.1 Excavation
5.6.1.1 General
The safety precautions as given in Part 7 'Constructional
Practices and Safety' shall be ensured.
5.6.1.2 Turf, topsoil or other surface material shall be
set aside, turf being carefully rolled and stacked for
use in reinstatement. All suitable broken surface
material and hard-core shall be set on one side for use
in subsequent reinstatement.
5.6.1.3 Excavated material shall be stacked sufficiently
away from the edge of the trench and the size of the
spoil bank shall not be allowed to become such as to
endanger the stability of the excavation. Spoil may be
carried away and used for filling the trench behind the
work.
5.6.1.4 Excavation shall proceed to within about
75 mm of the finished formation level. This final
75 mm is to be trimmed and removed as a separate
operation immediately prior to the laying of the pipes
or their foundations.
5.6.1.5 Unless specified otherwise by the Authority, the
width at bottom of trenches for pipes of different
diameters laid at different depths shall be as given below:
a) For all diameters, up to an average depth of
1 200 mm, width of trench in mm = diameter
of pipe + 300 mm;
b) For all diameters for depths above 1 200 mm;
width of trench in mm = diameter of pipe +
400 mm; and
c) Notwithstanding (a) and (b), the total width
of trench at the top should not be less than
750 mm for depths exceeding 900 mm.
5.6.1.6 Excavation in roads shall be so arranged, in
agreement with the proper authority, as to cause the
minimum obstruction to traffic. The methods to be
adopted shall depend on local circumstances.
5.6.1.7 All pipes, ducts, cables, mains or other services
exposed in the trench shall be effectively supported
by timber and/or chain or rope-slings.
5.6.1.8 All drainage sumps shall be sunk clear of the
work outside the trench or at the sides of manholes.
After the completion of the work, any pipes or drains
leading to such sumps or temporary sub-soil drains
under permanent work shall be filled in properly with
sand and consolidated.
5.6.2 Laying of Pipes
Laying of pipes shall be done in accordance with good
practice [9-1(31)].
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NATIONAL BUILDING CODE OF INDIA
5.6.3 Jointing
Ail sol! pipes, waste pipes, ventilating pipes and other
such pipes above ground shall be gas-tight. All sewers
and drains laid below the ground shall be water-tight.
Jointing shall be done in accordance with good practice
[9-1(31)].
5.6.4 Support or Protection for Pipes
5.6.4.1 General
It may be necessary to support or surround pipe sewers
or drains by means of concrete in certain
circumstances. Some of the suggested methods are
given in 5MA.2 to 5.6.4.4.
5.6.4.2 Bedding
Bedding (see Fig. 20) shall be rectangular in section
and shall extend laterally at least 150 mm beyond and
on both sides of the projection of the barrel of the pipe.
The thickness of the concrete below the barrel of the
pipe shall be not less than 100 mm for pipes under
150 mm diameter and 150 mm for pipes 150 mm and
over in diameter. Where bedding is used alone, the
concrete shall be brought up at least to the invert level
of the pipe to form a cradle and to avoid line contact
between the pipe and the bed.
150 rnrrj
^- "7
L — wj"
rV- v :;-:^
>*|||^^<w f t . • : : ^; ; .
V ; •. *•*.'"*
H
w
W = D+300 mm
where D is external diameter of the pipe
T = 4
100 mm for pipes under 150 mm
nominal dia
1 50 mm for pipes of 1 50 mm
nominal dia and over
Fig. 20 Bedding
5.6.4.3 Haunching
Concrete haunching (see Fig. 21) shall consist of:
a) A concrete bed as described for bedding
<w 5.6.4.2);
b) The full width of the bed carried up to the
level of the horizontal diameter of the pipe;
and
c) Splays from this level carried up on both sides
of the pipe, from the full width of the bed to
meet the pipe barrel tangentiaiiy.
1 , 50 mm
T =
w = n + soo mm
where D is external diameter of the pipe
"100 mm for pipes under 150 mm
nominal dia
I 1 50 mm for pipes of 1 50 mm
^ nominal dia and over
Fig. 21 Haunching
5.6.4.4 Surround or Encasing
The surround or encasing (see Fig. 22) shall be similar
to haunching up to the horizontal diameter of the pipe
and the top portion over this shall be finished in a semi-
circular form to give a uniform encasing for the top
half of the pipe.
150 mm
W = D + 300 mm
where D is external diameter of the pipe
Fig. 22 Surround or Encasing
5,6*5 Connection to Existing Sewers
The connection to an existing sewer shall, as far as
possible, be done at the manholes. Where it is
unavoidable to make connection in between two
manholes, the work of breaking into the existing sewer
and forming the connection shall be carried out by the
Authority or under its supervision.
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
75
5.6.5.1 Breaking into the sewer shall be effected by
the cautious enlargement of a small hole and every
precaution shall be taken to prevent any material from
entering the sewer. No connection shall be formed in
such a way as to constitute a projection into the sewer
or to cause any diminution in its effective size.
5.6.6 Back-Filling
5.6.6.1 Filling of the trench shall not be commenced
until the length of pipes therein has been tested and
passed (see 5.10.2).
5.6.6.2 All timber which may be withdrawn with
safety shall be removed as filling proceeds.
5.6.6.3 Where the pipes are unprotected by concrete
haunching, the first operation in filling shall be
carefully done to hand-pack and tamp selected fine
material around the lower half of the pipes so as to
buttress them to the sides of the trench.
5.6.6.4 The filling shall then be continued to 150 mm
over the top of the pipe using selected fine hand-packed
material, watered and rammed on both sides of the pipe
with a wooden rammer. On no account shall material
be tipped into the trench until the first 150 mm of filling
has been completed. The process of filling and tamping
shall proceed evenly so as to maintain an equal pressure
on both sides of the pipeline.
5.6.6.5 Filling shall be continued in layers not
exceeding 150 mm in thickness, each layer being
watered and well rammed.
5.6.6.6 In roads, surface materials previously
excavated shall be replaced as the top layer of the
filling, consolidated and maintained satisfactorily till
the permanent reinstatement of the surface is made by
the Authority.
5.6.6.7 In gardens, the top soil and turf, if any, shall
be carefully replaced.
5.7 Construction Relating to Conveyance of Rain
or Storm Water
5.7.1 Roof Gutters
Roof gutters shall be of any material of suitable
thickness. All junctions and joints shall be water-tight.
5.7.2 Rain-Water Pipes
Rain water pipes shall conform to the accepted
standards [9-1(32)].
5.7.3 Sub-soil Drain Pipes
5.7.3.1 Field drain pipes
Suitable pipes for this purpose are plain cylindrical
glazed water pipes, or concrete porous pipes though
the latter may prove unsuitable where sub-soil water
carries sulphates or is acidic. Trenches for these pipes
need be just wide enough at the bottom to permit laying
the pipes, which shall be laid with open joints to proper
lines and gradients.
It is advisable to cover the pipes with clinker free from
fine ash, brick ballast or other suitable rubble, or a
layer of inverted turf, brush-wood or straw before
refilling the trench, in order to prevent the infiltration
of silt through the open joints. Where the sub-soil drain
is also to serve the purpose of collecting surface water,
the rubble shall be carried upto a suitable level and
when required for a lawn or playing field, the remainder
of the trench shall be filled with pervious top soil. When
refilling the trenches, care shall be taken to prevent
displacement of pipes in line of levels. When they pass
near trees or through hedges, socket pipes with cement
or bitumen joints shall be used to prevent penetration
by roots.
5.7.3.2 French Drain
A shallow trench is excavated, the bottom neatly
trimmed to the gradient and the trench filled with
broken stone, gravel or clinker, coarse at the bottom
and finer towards the top.
5.8 Selection and Installation of Sanitary Appliances
5.8.1 Selection, installation and maintenance of
sanitary appliances shall be done in accordance with
good practice [9-1(33)].
5.9 Refuse Chute System
5.9.1 Refuse chute system is provided in multi-
storeyed buildings for transporting and collecting in a
sanitary way the refuse from floors at different heights.
The refuse is received from the successive floor
through the inlets located on the vertical system of
pipes that convey refuse through it and discharge it
into the collecting chamber from where the refuse is
cleared at suitable intervals.
5.9.2 This system has got three functionally important
components, namely, the chutes, the inlet hopper and
the collection chamber.
5.9.2.1 The chute imiy be carried through service
shafts meant for carrying drainage pipes. However, the
location shall be mostly determined by the position of
the inlet hopper and the collecting chamber that is most
convenient for the user. It should also be considered
to locate the chute away from living rooms in order to
avoid noise and smell nuisance.
5.9.2.2 In individual chute system, the inlet hopper
shall be located in the passage near the kitchen and in
the common chute system towards the end of the
common passage. Natural ventilation should be
adequate to prevent any possible odour nuisance. There
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NATIONAL BUILDING CODE OF INDIA
should be adequate lighting at this location. For ground
floor (floor 1), the inlet hoppes may be placed at a
higher level and a flight of steps may be provided for
using the same.
5.9.2.3 The collection chamber shall be situated at
ground level.
5.9.3 Requirements in regard to the design and
construction of refuse chute system shall be in
accordance with good practice [9-1(34)].
5.10 Inspection and Testing
5.10.1 Inspection
5.10.1.1 All sanitary appliances and fitments shall be
carefully examined for defects before they are installed
and also on the completion of the work.
5.10.1.2 Pipes are liable to get damaged in transit and,
not withstanding tests that may have been made before
despatch, each pipe shall be carefully examined on
arrival on the site. Preferably, each pipe shall be rung
with a hammer or mallet and those that do not ring
true and clear shall be rejected. Sound pipes shall be
carefully stored to prevent damage. Any defective pipes
shall be segregated, marked in a conspicuous manner
and their use in the works prevented.
5.10.1.3 Cast iron pipes shall be carefully examined
for damage to the protective coating. Minor damage
shall be made good by painting over with hot tar or
preferably bitumen. But if major defects in coating exit,
the pipes shall not be used unless recoated. Each pipe
shall be carefully re-examined for soundness before
laying.
5.10.1.4 Close inspection shall be maintained at every
stage in the work, particularly as to the adequacy of
timber supports used in excavation and the care and
thoroughness exercised in filling.
5.10.1.4.1 Careful note shall be kept of the condition
of any sewer, manhole or other existing work which
may be uncovered and any defects evident shall be
pointed out immediately to the Authority.
5.10.1.4.2 No work shall be covered over or
surrounded with concrete until it has been inspected
and approved by the Authority.
5.10.2 Testing
5.10.2.1 Comprehensive tests of all appliances shall
be made by simulating conditions of use. Overflow
shall be examined for obstructions.
5.10.2.2 Smoke test
All soil pipes, waste pipes, and vent pipes and all other
pipes when above ground shall be approved gas-tight
by a smoke test conducted under a pressure of 25 mm
of water and maintained for 15 min after all trap seals
have been filled with water. The smoke is produced
by burning only waste or tar paper or similar material
in the combustion chamber of a smoke machine.
Chemical smokes are not satisfactory.
5.10.2.3 Water test
5.10.2.3.1 For pipes other than cast iron
Glazed and concrete pipes shall be subjected to a test
pressure of at least 1.5 m head of water at the highest
point of the section under test. The tolerance figure of
2 litres/cm of diameter/km may be allowed during a
period of 10 min. The test shall be carried out by
suitably plugging the low end of the drain and the ends
of connections, if any, and filling the system with water.
A knuckle bend shall be temporarily jointed in at the
top end and a sufficient length of the vertical pipe
jointed to it so as to provide the required test head, or
the top end may be plugged with a connection to a
hose ending in a funnel which could be raised or
lowered till the required head is obtained and fixed
suitably for observation.
Subsidence of the test water may be due to one or more
of the following causes:
a) absorption by pipes and joints;
b) sweating of pipes or joints;
c) leakage at joints or from defective pipes; and
d) trapped air.
Allowance shall be made for (a) by adding water until
absorption has ceased after which the test proper should
commence. Any leakage will be visible and the
defective part of the work should be cut out and made
good. A slight amount of sweating which is uniform
may be overlooked, but excessive sweating from a
particular pipe or joint shall be watched for and taken
as indicating a defect to be made good. A slight amount
of sweating which is uniform may be overlooked, but
excessive sweating from a particular pipe or joint shall
be watched for and taken as indicating a defect to be
made good.
NOTE — This test will not be applicable to sanitary pipe work
above ground level.
5.10.2.3.2 For cast iron pipes
Cast iron sewers and drains shall be tested as for glazed
and concrete pipes. The drain plug shall be suitably
strutted to prevent their being forced out of the pipe
during the test.
5.10.2.4 Tests for straightness and obstruction
The following tests shall be carried out:
a) by inserting at the high end of the sewer or
drain a smooth ball of a diameter 13 mm
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
77
less than the pipe bore. In the absence of
obstruction, such as yarn or mortar projecting
through the joints, the ball should roll down
the invert of the pipe, and emerge at the lower
end; and
b) by means of a mirror at one end of the line
and lamp at the other. If the pipeline is
straight, the full circle of light may be
observed. If the pipe line is not straight, this
will be apparent. The mirror will also indicate
obstruction in the barrel.
5.10.2.5 Test records
Complete records shall be kept of all tests carried out
on sewers and drains both during construction and after
being put into service.
5.11 Maintenance
5.11.1 General
Domestic drainage system shall be inspected at regular
intervals. The system shall be thoroughly cleaned out
at the same time and any defects discovered shall be
made good.
5.11.2 Cleaning of Drainage System
5.11.2.1 Sewer maintenance crews, when entering a
deep manhole or sewer where dangerous gas or oxygen
deficiencies may be present, shall follow the following
procedures:
a) allow no smoking or open flames and guard
against parks.
b) erect warning signs.
c) use only safety gas-proof, electric lighting
equipment.
d) test the atmosphere for noxious gases and
oxygen deficiencies (presence of hydrogen
sulphide is detected using lead acetate paper
and that of oxygen by safety lamps).
e) if the atmosphere is normal, workmen may
enter with a safety belt attached and with two
men available at the top. For extended jobs,
the gas tests shall be repeated at frequent
intervals, depending on circumstances.
if oxygen deficiency or noxious gas is found,
the structure shall be ventilated with pure air
by keeping open at least one manhole cover
each on upstream and downstream side for
quick exit of toxic gases or by artificial means.
The gas tests shall be repeated and the
atmosphere cleared before entering. Adequate
ventilation shall be maintained during this
work and the tests repeated frequently.
g) if the gas or oxygen deficiency is present and
it is not practicable to ventilate adequately
before workers enter, a hose mask shall be
worn and extreme care taken to avoid all
sources of ignition. Workers shall be taught
how to use the hose equipment. In these cases,
they shall always use permissible safety lights
(not ordinary flash lights), rubber boots or
non-sparking shoes and non-sparking tools;
h) Workmen descending a manhole shaft to
inspect or clean sewers shall try each ladder
step or rung carefully before putting the full
weight on it to guard against insecure
fastening due to corrosion of the rung at the
manhole wall. When work is going on in deep
sewers, at least two men shall be available
for lifting workers from the manhole in the
event of serious injury; and
j) Portable air blowers, for ventilating manhole,
are recommended for all tank, pit or manhole
work where there is a question as to the
presence of noxious gas, vapours or oxygen
deficiency. The Motors for these shall be
of weather proof and flame-proof types;
compression ignition diesel type (without
sparking plug) may be used. When used, these
shall be placed not less than 2 m away from
the opening and on the leeward side protected
form wind, so that they will not serve as a
source of ignition for any inflammable gas
which might be present. Provision should be
made for ventilation and it should be of the
forced type which can be provided by a
blower located at ground level with suitable
flexible ducting to displace out air from the
manhole.
5.11.2.2 The following operations shall be carried out
during periodical cleaning of a drainage system.
a) The covers of inspection chambers and
manholes shall be removed and the side
benching and channels scrubbed;
b) The interceptive trap, if fitted, shall be
adequately cleaned and flushed with clean
water. Care shall be taken to see that the
stopper in the rodding arm is securely
replaced;
c) All lengths of main and branch drains shall
be rodded by means of drain rods and a
suitable rubber or leather plunger. After
rodding, the drains shall be thoroughly
flushed with clean water. Any obstruction
found shall be removed with suitable drain
cleaning tools and the system thereafter shall
be flushed with clean water;
d) The covers of access plates to all gullies shall
be removed and the traps plunged and flushed
78
NATIONAL BUILDING CODE OF INDIA
out thoroughly with clean water. Care shall
be taken not to flush the gully deposit into
the system;
e) Any defects revealed as a result of inspection
or test shall be made good;
f) The covers or inspection chambers and gullies
shall be replaced, bedding them in suitable
grease or other materials; and
g) Painting of ladders/rings in deep manholes
and external painting of manhole covers shall
be done with approved paints.
5.11.3 All surface water drains shall be periodically
rodded by means of drain rods and a suitable rubber
or leather plunger. After rodding, they shall be
thoroughly flushed with clean water. Any obstruction
found shall be removed with suitable drain cleaning
tools.
5.11.4 All sub-soil drains shall be periodically
examined for obstruction at the open joints due to the
roots of plants or other growths.
6 SOLID WASTE MANAGEMENT
6.1 General
6.1.1 Efficient collection and disposal of domestic
garbage from a building or activity area is of significant
importance to public health and environmental
sanitation and, therefore, an essential part of the
construction of the built environment. Notwithstanding
the provisions given herein, the solid waste
management shall have to comply with relevant
statutory Rules and Regulations in force from time-
to-time. In this regard, the provisions of the following
shall govern the procedures for handling, treatment,
etc of solid wastes as applicable to the concerned
building occupancy:
a) Manufacture, Storage and Import of Hazardous
Chemical Rules, 1989;
b) Bio-Medical Waste (Management and Handling
Rules, 1998; and
c) Municipal Solid Wastes (Management and
Handling) Rules, 2000.
6.1.2 The provisions relating to solid waste
management given in 6.2 are applicable to wastes in
general, and specifically exclude the hazardous
chemical wastes and bio-medical waste.
6.2 Solid Waste Management Systems
6.2.1 In designing a system dealing with collection of
domestic garbage for a built premises/community/
environment, the aim shall be to provide speedy and
efficient conveyance as an essential objective for
design of the system. The various available systems
may be employed in accordance with 6.2.1 to 6.2.3,
which may be adopted individually or in combination
as appropriate in specific situations.
6.2.2 Refuse Chute System
6.2.2.1 Refuse chute system is a convenient and safe
mode of collection of domestic solid wastes from
buildings exceeding 3 storeys. The internal diameter
of the chute shall be at least 300 mm.
The access to the refuse chute shall be provided from
well ventilated and well illuminated common corridor
or lobby and preferably it should not be located
opposite or adjacent to entry of individual flats or lift.
6.2.2.2 Opening for feeding of refuse chute
Opening, with top or bottom hinged shutters with
appropriate lockable latch, shall be provided for
convenient accessing of the refuse chute by users.
6.2.2.3 Refuse collection chamber
The collection chamber may be located in ground floor
or basement level, provided appropriate arrangement
is made for (a) drainage of the collection pit by gravity
flow to ensure its dryness, (b) an appropriate ramp
access is provided for convenient removal of garbage
from the collection pit, and (c) satisfactory ventilation
for escape of gas and odour. The floor of the chamber
shall be provided with drainage through a 100 mm
diameter trap and screen to prevent any solid matters
flowing into the drain and the drain shall be connected
to the sewer line. The floor shall be finished with
smooth hard surface for convenient cleaning.
The height of the collection chamber and vertical
clearance under the bottom level of garbage chute shall
be such that the garbage trolley can be conveniently
placed.
The collection chamber shall be provided with
appropriate shutter to prevent access of all scavenging
animals like the cattle, dogs, cats, rats, etc.
6.2.2.4 Material for chute
The chute may be of masonry or suitable non-corrosive
material. Further the material should be rigid with
smooth internal finish, high ductility and alkali/acid
resistant properties.
6.2.2.5 Size of trolley
The size of the garbage trolley shall be adequate for
the daily quantity of garbage from a chute. For working
out quantity of garbage, a standard of approximately
0.75 kg/person may be taken.
6.2.3 Dumb-Waiter
In high rise buildings with more than 8 storeys,
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
79
electrically operated dumb-waiters may be used for
carrying domestic garbage in packets or closed
containers. For handling of garbage by dumb-waiters
in a building, a garbage chamber shall have to provided
either at ground floor or basement level and the
provisions of garbage collection chamber for chute as
given in 6.2.2 shall apply.
6.2.3.1 Shutters for dumb-waiter
The shutters for dumb-waiter and garbage collection
chamber shall be provided with shutters with same
consideration as in the case of garbage chute. However,
the dumb-waiter shall be made child-proof.
6.2.3.2 Sorting of garbage to remove toxic matters
from garbage
Before feeding the garbage to compost pits the
following objects need to be removed:
a) inert matters like glass, metals, etc;
b) chemicals, medicines, batteries of any kind;
c) polythene and plastic materials; and
d) any other non-biodegradable material.
These separated items shall be handled separately, and
may be scrapped or recycled, etc as appropriate.
6.2.4 Treatment by Vermi-Composting
Vermi-compost treatment shall be provided to the
organic wastes in composting pits located in shade.
The pits shall be used to receive the garbage in a
predetermined (periodic) cyclic order. (For example 5
pits to receive garbage in 5 days and these 5 pits
together accepting daily load of garbage.) The gross
area of the composting pits may be about 0.1 m 2 per
person.
6.2.4.1 The site for vermi-composting shall be
enclosed from all sides with appropriate fencing (for
keeping scavenging animals away) and provided with
a small door for accessing the enclosed premises.
6.2.4.2 Composting pits shall be constructed
either under the shade of trees (except Neem tree) or
created by sheeting or shade net so as to keep the pits
under shade. The pits shall be easily accessed for
convenient shifting of garbage from trolleys carrying
garbage.
6.2.4.3 The composting pits shall be made in a manner
that the pits do not have the risk of inundation by water.
This may be achieved by appropriately raising the base
level of the pit and providing weep holes from sides.
Height of side walls of compost pits need to be 0.6 m
to 0.75 m high. The bottom of the pit without any lining
is preferred.
6.2.4.4 Initiation of composting pits shall be done by
providing a 75 mm thick layer of cow dung (fresh or
partially decomposed) spreading 1 kg of vermi-
compost and covering it with 75 mm to 100 mm thick
layer of dry leaves/grass, etc and sprinkling of water
and allowing to decompose naturally for about 10 to
15 days.
6.2.4.5 Sorted garbage free from inert and toxic
matters shall be applied in the composting pit in layers
of 75 mm and spread, and covered with a layer of
75 mm thick dry leaves followed by sprinkling of
water.
6.2.4.6 The compost may be removed from the bottom
of the compost pit after intervals of 3 to 6 months. The
compost so made may be used in appropriate
horticultural and related applications.
80
NATIONAL BUILDING CODE OF INDIA
ANNEX A
(Clause 3.2.1)
APPLICATION FORM FOR TEMPORARY/PERMANENT SUPPLY OF WATER/FOR
ADDITIONS AND/OR ALTERATIONS FOR SUPPLY OF WATER
I/We hereby make application
to the* for the temporary/
permanent supply of water for the following additions
and/or alterations to the water supply requirements and
water fittings at the premises
Ward No Street No Road/
Street known as for
the purpose described below and agreed to pay such
charges as the Authority may from time-to-time be
entitled to make and to conform to all their byelaws
and regulations licensed
plumber, has been instructed by me/us to carry out the
plumbing work.
Description of the premises:
Address:
Purpose for which water is required: .
The connection/connections taken by me/us for
temporary use, shall not be used by me/us for
permanent supply unless such a permission is granted
to me/us in writing by the Authority.
I/We hereby undertake to give the*
due notice of any
additions or alterations to the above mentioned supply
which I/we may desire to make.
My/Our requirements of water supply are as under:
a) I/We request that one connection be granted
for the whole of the premises.
b) I/We request that separate connections may
be granted for each floor and I/we undertake
to pay the cost of the separate connections.
c) My/Our probable requirements for trade
purpose are litres per day
and for domestic purposes are
litres per day.
d) Our existing supply is litres
per day. Our additional requirement of supply
is litres per day.
e) The details as regards proposed additions and
alterations in fittings are as follows:
Signature of the licensed plumber
Name and address of the licensed plumber .
Signature of the applicant
Name and address of the applicant
Date
Date.
NOTES
1 Please strike out whatever is not applicable.
2 The application should be signed by the owner of the premises or his constituted attorney and shall be countersigned by the licensed
plumber.
* Insert here the name of the Authority.
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
81
ANNEX B
(Clause 3.2.3)
FORM FOR LICENCED PLUMBER'S COMPLETION CERTIFICATE
Certified that I/we have completed the plumbing work Address ..
of water connection No for the
premises as detailed below. This may be inspected and
connection given. Situation
Ward No .....Road/Street .,.. *
Size of main on .
Locality Street •
Where main is situated .
Block No ...House No
Size of service pipe ...
Existing water connection No. (if any) Size of ferrule
No. of taps No. of closets
Owned by Na of other fittings and appliances
Owner's address
Road cutting and repairing fee
Applicant's name
sonof PaidRs (Receipt No
dated ) (receipt enclosed)
Dated Signature of the licensed plumber
Name and address of the licensed plumber
The Authority's Report
Certified that the communication and distribution pipes and all water fittings have been laid, applied and executed
in accordance with the provisions of bye-laws, and satisfactory arrangements have been made for draining off
waste water.
Connection will be made on
Date The Authority ,
82 NATIONAL BUILDING CODE OF INDIA
ANNEX C
(Clause 3.3.1)
APPLICATION FOR DRAINAGE OF PREMISES
I/We hereby make application to the * .
for permission to drain the premises.
Ward No
Road/Street known as
The sanitary arrangement and drains of the said
premises are shown in the accompanying plans and a
description of the specification of the work/material
used is also appended (Annex D).
« N I/We undertake to carryout the work in accordance with
"'" Part 9 'Plumbing Services, Section 1 Water Supply,
Drainage and Sanitation' of the Code.
Signature of the licensed plumber
Name and address of the licensed plumber
Signature of the owner
Name and address
Date Date
NOTE — The application should be signed by the owner of the premises and shall be countersigned by the licensed plumber.
* Insert the name of the Authority.
ANNEX D
(Clause 3.3.3.2)
FORM FOR DETAILED DESCRIPTION OF WORK AND
SPECIFICATION OF MATERIALS
1 ) Separation of rain-water and foul water .
2) Rain-water drains, curbs and points of
discharge
3) Rain-water gutters, pipes or spouts where
discharging
4) Open-full- water drains, materials, sizes, curbs
and other means places, verandahs, latrines
5) Silt-catcher and grating, size and position
6) Drains
a) Main sewage drains: Fall .
Size.
b) Branch drains: Fall .
Size.
c) Materials
d) Method of jointing
7) Bedding of pipes:
a) Method of bedding
b) Thickness and width of beds of concrete
c) Thickness of concrete round pipes
8) Protection of drain laid under wall .
9) Traps, description and intercepter:
a) Lavatory waste pipes
b) Bath waste pipes
c) Sink
d) Gully-traps
e) Water-closet traps
f) Grease traps
g) Slop sink
h) Urinal
j) Others
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
83
10) Manholes and inspection chambers:
a) Thickness of walls
b) Description of bricks
c) Description of rendering
d) Description of invert channels
e) Depth of chambers
f) Size and description of cover and manner
of fixing
11) Ventilation of drain:
a) Position — Height above nearest ground
level
b) Outlet shaft position of terminal at top
12) Soil pipe, waste pipe and ventilating pipe
connections:
a) Lead and iron pipes
b) Lead pipe of trap with cast iron pipe
c) Stoneware pipe or trap with lead pipe ...
d) Lead soil pipe or trap with stoneware pipe
or trap
e) Cast iron pipe with stoneware drain
f) Stoneware trap with cast iron soil pipe
1 3) Ventilation of water-closet trap sink, lavatory
and other traps material and supports.
14) Water-closets (apartments);
a) i) At or above ground level
ii) Approached from
iii) Floor material
iv) Floor fall towards door
v) Size of window opening in wall made
to open
vi) Position of same
vii) Means of constant ventilation
viii) Position of same
b) Water-closet apparatus:
i) Description of pan, basin, etc
Kind
ii) Flushing cistern
iii) Material of flushing pipe
iv) Internal diameter
v) Union with basin
15) Sanitary fittings, water storage tank, etc:
a) Number and description of sanitary
fittings in room and rooms in which they
are to be installed
b) Capacity and position of water storage
tanks
c) Size and number of draw off taps and
whether taken off storage tanks or direct
from main supply
d) Details of draw off taps, that is, whether
they are of plain screw down pattern or
'waste not' and description of any other
sanitary work to be carried out not
included under above headings
16) Depth of sewer below surface of street
17) Level of invert of house drain at point of
junction:
a) with sewer
b) Level of invert of sewer at point of
junction with house drain
c) Distance of nearest manhole on sewer
from the point at which the drain leaves
the premises
18) Schedule of pipes:
Description of Pipe/Drain
a) Sub-soil drains
b) Main sewage drains
c) Branch sewage drains
d) Soil pipes
e) Ventilating pipes other than soil pipes
f) Waste pipes
g) Rain-water pipes
h) Anti-syphon pipes
Materials
Diameter
Weight Method of Jointing
Date
Signature of the licensed plumber
Name and address of the licensed plumber
84
NATIONAL BUILDING CODE OF INDIA
ANNEXE
{Clause 3.3.5)
FORM FOR LICENCED PLUMBER'S COMPLETION CERTIFICATE
Certified that I/we have completed the plumbing work Block No
of drainage and sanitation system for the premises as House No
detailed below. This may be inspected, approved and
connection given. Details of work ■
Ward No .
Street
Locality..
The work was sanctioned by the Authority*
vide
Signature of the owner Signature of the licensed plumber
Name and address Name and address of the licensed plumber
Date
The Authority's Report
Certified that the plumbing work of drainage and sanitation system for the premises, have been laid, applied,
executed in accordance with Part 9 'Plumbing Services, Section 1 Water Supply, Drainage and Sanitation' of the
Code.
Drainage connection to the main sewer will be made on
Date The Authority
* Insert the name of the Authority.
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION 85
ANNEX F
(Clause 4.6.4)
NOMOGRAM OF HAZEN AND WILLIAM'S EQUATION
E-l Examples of the use of nomogram are given
below:
0-1
-
0*26
-
0*3
0-2
—
03
-
—100
0-4
—
a
0-4
»
UJ
-
x ^
-70
ae
£ 1
L
o
0-5
r«o
UJ
x
-50
g 2
ae ""
0-6
-40
; 3
-
a. -
0-7
r 30
« 5
t/1
0-8
1-200
a.
0£ -
►- _
0-9
r 20
w 10
U .
o
z
8
f-150
METRE
O <
•- -
10
UJ
l/>
a:
in
a.
-10
: 8
- 6
E
E
rioo
r 90
r 80
7 70
• 30
8 40
2 50
X
^
o -
o .
-J
UJ —
> -
1-5
in
'- 5
*
Ul
-60
S 10 °
2-0
*-
- 4
0l.
-50
S 200
3
"
O
2
- 3
U.
o
-40
-* 300
O
QC
500
_
3-0
U.
- 2
111
- 30
UJ
1000 =
-1
<
o
-20
"
4*0
- 15
-0*5
-0-4
-0-3
- 0-25
Nomogram ofHazen & Williams
£#W
ation
(c = K
J0)
Example 1
Find the total friction loss in 25 mm G.I. Pipe
discharging 0.251/s in a total length of 300 m.
Procedure
Q = 0.25 1/s
Pipe0 = 25 mm
Frictional loss from nomogram
= 30 m/1 000 m
Total friction loss in 300 m length
= x300m = 9m
1000
Example 2
Find suitable diameter pipe to carry
15 1/s from service line to overhead tank.
Total length of service main = 200 m
Residual pressure available at the take off point on
supply line is 15 m.
Procedure
Available head = 15 m
Deduct residual head = 2m
Deduct 10 percent for losses in bends and specials
= L3m
Friction head available for loss in pipe of
= 1 ooo m !!^iooo = 000m
2 000
From the nomogram for a discharge of 15 1/s and
friction loss of 58.5 m/1 000 m diameter of nearest
commercial size of pipejis 100 mm diameter.
86
NATIONAL BUILDING CODE OF INDIA
LIST OF STANDARDS
The following list records those standards which are
acceptable as * good practice' and 'accepted standards'
in the fulfillment of the requirements of the Code. The
latest version of a standard shall be adopted at the time
of enforcement of the Code. The standards listed may
be used by the Authority as a guide in conformance
with the requirements of the referred clauses in the
Code.
IS No.
(1) 11208: 1985
(2) 10500 : 1991
(3) 2041 : 1995
804 : 1967
(4) 3076 : 1985
4984 : 1995
4985 : 2000
(5) 2065 : 1983
(6) 3114:1994
(7) 782 : 1978
(8) 5822 : 1994
(9) 6530 : 1972
(10) 783 : 1985
(11) 7634
Title
Guidelines for registration of
plumbers
Specification for drinking
water (first revision)
Specification for steel plates
for pressure vessels used at
moderate and low temperature
(second revision)
Specification for rectangular
pressed steel tanks (first
revision)
Specification for low density
polyethylene pipes for
potable water supplies
(second revision)
Specification for high
density polyethylene pipes
for potable water supplies
(fourth revision)
Specification for unplasticized
PVC pipes for potable water
supplies (third revision)
Code of practice for water
supply in buildings (second
revision)
Code of practice for laying
of cast iron pipes (second
revision)
Specification for caulking
lead (third revision)
Code of practice for laying
of welded steel pipes for
water supply (second revision)
Code of practice for laying
of asbestos cement pressure
pipes
Code of practice for laying
of concrete pipes (first
revision)
Code of practice for plastics
pipe, work for potable water
supplies:
IS No.
(Part 2) : 1975
(Part 3) : 2003
(12) 783 : 1985
3114:1994
5822 : 1994
6530 : 1972
7634
(Part 2): 1975
(Part 3) : 2003
(13) 2692: 1989
(14) 302
(Part 1) : 1979
2082 : 1993
(15) 7558 : 1974
(16) 6295 : 1986
(17) 771
(Part 1) : 1979
(Part 2) : 1985
Title
Laying and jointing
polyethylene (PE) pipes
Laying and jointing of
UPVC pipes (first revision)
Code of practice for laying
of concrete pipes (first
revision)
Code of practice for laying
of cast iron pipes (second
revision)
Code of practice for laying
of welded steel pipes for
water supply (second
revision)
Code of practice for laying
of asbestos cement pressure
pipes
Code of practice for plastics
pipe, work for potable water
supplies:
Laying and jointing
polyethylene (PE) pipes
Laying and jointing of
UPVC pipes (first revision)
Specification for ferrules for
water services (second
revision)
General and safety
requirements for household
and similar electrical
appliances: Part 1 General
(fifth revision)
Stationary storage type
electric water heaters (third
revision)
Code of practice for domestic
hot water installations
Code of practice for water
supply and drainage in high
altitudes and/or sub-zero
temperature regions (first
revision)
Specification for glazed fire-
clay sanitary appliances:
General requirements (second
revision)
Specific requirements of
kitchen and laboratory sinks
(third revision)
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
87
IS No.
(Part 3/Sec 1) :
1979
(Part 3/Sec 2) :
1985
(Part 4) : 1979
(Part 5) : 1979
(Part 6) : 1979
(Part 7): 1981
772 : 1973
773 : 1988
774 : 1984
775 : 1970
1700: 1973
2326 : 1987
2548
(Part 1) : 1996
(Part 2): 1996
2556
(Part 1) : 1994
(Part 2) : 1994
Title
Specific requirements of
urinals, Section 1 Slab urinals
(second revision)
Specific requirements of
urinals, Section 2 Stall urinals
(third revision)
Specific requirements of
postmortom slabs (second
revision)
Specific requirements of
shower trays (second revision)
Specific requirements of
bed-pan sinks (second
revision)
Specific requirements of slop
sinks (second revision)
Specification for general
requirements for enamelled
cast iron sanitary appliances
(second revision)
Specification for enamelled
cast iron water-closets
railway coaching stock type
(fourth revision)
Specification for flushing
cistern for water-closets and
urinals (other than plastic
cistern) (fourth revision)
Specification for cast iron
brackets and supports for
washbasins and sinks (second
revision)
Specification for drinking
fountains (first revision)
Specification for automatic
flushing cisterns for urinals
(second revision)
Specification for plastic seats
and covers for water-closets:
Thermoset seats and covers
(fifth revision)
Thermo plastic seats and
covers (fifth revision)
Specification for vitreous
sanitary appliances (vitreous
china):
General requirements (third
revision)
Specific requirements of
wash-down water-closets
(fourth revision)
IS No.
(Part 3) : 1994
(Part 4): 1994
(Part 5) : 1994
(Part 6) : 1995
(Part 7): 1995
(Part 8): 1995
(Part 9): 1995
(Part 14) : 1995
(Part 15) : 1995
(Part 16) : 2002
(Part 17) : 2001
3489 : 1985
6411:1985
7231 : 1994
8718 : 1978
8727 : 1978
9076 : 1979
11246: 1992
Title
Specific requirements of
squatting pans (fourth
revision)
Specific requirements of
wash basins (third revision)
Specific requirements of
laboratory sinks (third
revision)
Specific requirements of
urinals and partition plates
(fourth revision)
Specific requirements of
accessories f of; sanitary
appliances (third revision)
Specific requirements of
sipfaonic wash-down water-
-closets (fourth revision)
Specific requirements of
bidets (fourth revision)
Specific requirements of
integrated squatting pans
(first revision)
Specific requirements of
universal water-closets (first
revision)
Specific requirements for
wash-down wall mounted
water-closets
Specific requirements for
wall mounted bidets
Specification for enamelled
steel bath tubs (first revision)
Specification for gel-coated
glass fibre reinforced
polyester resin bath tubs
(first revision)
Specification for plastic
flushing cisterns for water-
closets and urinals (second
revision)
Specification for vitreous
enamelled steel kitchen
sinks
Specification for vitreous
enamelled steel washbasins
Specification for vitreous
integrated squatting pans for
marine use
Specification for glass fibre
reinforced polyester resins
(GRP) squatting pans (first
revision)
88
NATIONAL BUILDING CODE OF INDIA
IS No.
13983 : 1994
(18) 651 : 1992
3006 : 1979
(19) 458 : 2003
784 : 2001
1916: 1989
4350 : 1967
7319 : 1974
(20) 1536 : 2001
1537 : 1976
1538 : 1993
3989 : 1984
7181 : 1986
(21) 1592:2003
1626
Title
Specification for stainless
steel sinks for domestic
purposes
Specification for salt glazed
stoneware pipes and fittings
(fifth revision)
Specification for chemically
resistant salt glazed
stoneware pipes and fittings
(first revision)
Specification for precast
concrete pipes (with and
without reinforcement)
(fourth revision)
Specification for prestressed
concrete pipes (including
specials) (second revision)
Specification for steel
cylinder with concrete lining
and coating (first revision)
Specification for concrete
porous pipes for under
drainage
Specification for perforated
concrete pipes
Specification for centrifugally
cast (spun) iron pressure
pipes for water, gas and
sewage (fourth revision)
Specification for vertically
cast iron pressure pipes for
water, gas and sewage (first
revision)
Specification for cast iron
fittings for pressure pipes for
water, gas and sewage (third
revision)
Specification for centrifugally
cast (spun) spigot and
socket-soil, waste and
ventilating pipes and fittings
and accessories (second
revision)
Specification for horizontally
cast iron double flanged
pipes for water, gas and
sewage (first revision)
Specification for asbestos
cement pressure pipes and
joints (fourth revision)
Specification for asbestos
cement building pipes and
IS No.
(Part 1) : 1994
(Part 2): 1994
(Part 3): 1994
6908 : 1991
(22) 404
(Part 1) : 1993
(23) 13592 : 1992
14333 : 1996
14735 : 1999
(24) 2470
(Part 1) : 1985
(Part 2) : 1985
5611 : 1987
(25) 5329 : 1983
(26) 2212 : 1991
(27) 5455 : 1969
(28) 1726: 1991
Title
pipe fittings, gutters and gutter
fittings, and roofing fittings:
Pipes and pipe fittings
(second revision)
Gutters and gutter fittings
(second revision)
Roofing accessories (second
revision)
Specification for asbestos
cement pipes and fittings for
sewerage and drainage (first
revision)
Specification for lead pipes:
Part 1 For other than chemical
purposes (third revision)
Specification for UPVC pipes
for soil and waste discharge
systems inside buildings
including ventilation and
rainwater system
Specification for high
density polyethylene pipe for
sewerage
Specification for
unplasticized polyvinyl
chloride (UPVC) injection
moulded fittings for soil and
waste discharge system for
inside and outside buildings
including ventilation and rain
water system
Code of practice for
installation of septic tanks:
Design criteria and
construction (second revision)
Secondary treatment and
disposal of septic tank
effluent (second revision)
Code of practice for waste
stabilization ponds (facultative
type) (first revision)
Code of practice for sanitary
pipe work above ground for
buildings (first revision)
Code of practice for brickwork
(first revision)
Specification for cast iron
steps for manholes
Specification for cast iron
manhole covers and frames
(third revision)
PART 9 PLUMBING SERVICES — SECTION 1 WATER SUPPLY, DRAINAGE AND SANITATION
89
IS No.
12592 : 2002
(29) 4111
(Parti): 1986
(30) 14961 : 2001
(31) 783: 1985
1742 : 1983
3114: 1994
4127 : 1983
Title
Specification for precast
concrete manhole covers and
frames (first revision)
Code of practice for ancillary
structures in sewerage
system: Part 1 Manholes
(first revision)
Guidelines for rain water
harvesting in hilly areas by
roof water collection system
Code of practice for laying
of concrete pipes (first
revision)
Code of practice for building
drainage (second revision)
Code of practice for laying
of cast iron pipes (second
revision)
Code of practice for laying
IS No.
6530 : 1972
(32) 1729 : 2002
(33) 2064: 1993
(34) 6924 : 1973
Title
of glazed stoneware pipes
(first revision)
Code of practice for laying
of asbestos cement pressure
pipes
Specification for cast iron
ductile iron drainage pipes
and pipe fittings for grand
non-pressure pipe line socket
and spigot series (second
revision)
Code of practice for selection,
installation and maintenance
of sanitary appliances (second
revision)
Code of practice for the
construction of refuse
chutes in multi-storeyed
buildings
90
NATIONAL BUILDING CODE OF INDIA
NATIONAL BUILDING CODE OF INDIA
PART 9 PLUMBING SERVICES
Section 2 Gas Supply
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 PRESSURE REGULATIONS
4 SERVICE SHUT-OFF VALVES
5 EXISTING WORK
6 RULES FOR TURNING GAS ON
7 RULES FOR SHUTTING OFF THE GAS
8 INSTALLATION OF GAS PIPES
9 INSPECTION OF SERVICES
10 LEAKAGE CHECK
1 1 USE OF LIQUEFIED PETROLEUM GAS
LIST OF STANDARDS
5
5
5
6
6
6
6
6
9
12
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
This Section covers the safe use of gas for fuel or lighting purposes in buildings.
The use of gas for fuel and lighting purposes in buildings has begun in some parts of the country and with the
advent of new petroleum complexes, community gas supply is bound to become one of the important services
like electricity and water supply in buildings.
The use of liquefied petroleum gas supplied in containers and cylinders is already quite popular. On release of
pressure, by opening the valve, they readily convert into the gaseous phase. In this state they present a hazard
comparable to any inflammable natural or manufactured gas, except that being heavier than air, low level ventilation
is necessary to avoid inflammable concentration of gas.
A minimum set of safety regulations are, therefore, laid down to safeguard the gas piping installation and the
mode of operation in the interest of public safety.
The first version of this part was prepared in 1970 and was subsequently revised in 1983. In the first revision, the
safe distance between gas piping and electrical wiring system was modified*as well as between gas piping and
steam piping was incorporated. Additional information regarding the handling, use, storage and transportation of
LPG in cylinders exceeding 500 ml water capacity were included. Provisions relating to LPG cylinders, installations
regarding some aspects, such as jointing compound used at joints, painting of gas piping, details of fire
extinguishers, total quantity of LPG at stationary and portable installations in proportion to the floor area were
added. Also, some provisions of LPG bulk storage installations were introduced.
As a result of experience gained in implementation of 1983 version of the Code and feed back received a need to
revise this part was felt. This revision has, therefore, been prepared to take care of these. The significant changes
incorporated in this draft revision include:
a) Provision with regard to pressure regulations have been modified.
b) In the provision of service shut-off valves, number of additional shut-off valves have been specified.
c) In the provision of installation of gas pipe, new materials for pipes have also been mentioned. The
minimum diameter for gas pipe has been reduced to 8 mm. The colour for pipe line for supplying
natural gas has been specified. The provisions regarding protection against the corrosion have been
modified. Also, the process of installation of meters have been clarified.
d) Additional method for detection of leakage of gas has been recommended.
e) Also, a few more terminologies have been added.
The information regarding the use of liquefied pertroleum gas has been largely based on the following Indian
Standards:
IS No. Title
6044 Code of practice for liquefied petroleum gas storage installations:
(Part 1) : 2000 Commercial and industrial cylinder installations (first revision)
(Part 2) : 2001 Commercial, industrial and domestic bulk storage installations (first revision)
All standards, whether given herein above or cross-referred to in the main text of this Section, are subject to
revision. The parties to agreement based on this Section are encouraged to investigate the possibility of applying
the most recent editions of the standards.
PART 9 PLUMBING SERVICES — SECTION 2 GAS SUPPLY
NATIONAL BUILDING CODE OF INDIA
PART 9 PLUMBING SERVICES
Section 2 Gas Supply
1 SCOPE
1.1 This Section covers the requirements regarding the
safety of persons and property for all piping uses and
for all types of gases used for fuel or lighting purposes
in buildings.
1.2 This Section does not cover safety rules for gas
burning appliances.
2 TERMINOLOGY
2.1 For the purpose of this Section, the following
definitions shall apply.
2.1.1 Appliance Valve — A device that will shut-off
the gas supply to the burner(s).
2.1.2 Authority Having Jurisdiction — The Authority
which has been created by a statute and which, for the
purpose of administering the Code/Part, may authorize
a committee or an official to act on its behalf;
hereinafter called the 'Authority'.
2.1.3 Customer's/Consumer's Connection — Piping
tapped on riser to supply each individual customer/
consumer.
2.1.4 Gas Fitter — An employee of the gas supplying
organization.
2.1.5 Pilot — A small flame which is utilized to ignite
the gas at the main burner(s).
2.1.6 Pressure Regulator — A device designed to
lower the pressure of gas coming from the distribution
main and to maintain it practically constants
downstream. This normal operation pressure shall be
practically in all cases that of the gas appliances used.
2.1.7 Purge — To free a gas conduit of air or gas or a
mixture of gas and air.
2.1.8 Qualified Installing Agency — An individual,
firm or agency which either in person or through a
representative is engaged in and is responsible for the
installation or replacement of gas piping on the outlet
side of the gas meter, or the connection, installation or
repair of gas supply piping and appliances within a
building, and who is experienced in such work, familiar
with all precautions required, and who has complied
with all the requirements as to qualification,
registration, licensing, etc, of the Authority.
2.1.9 Riser — Piping usually vertical on most of its
length that supplies gas from the service to the various
storeys of the building.
2.1.10 Service Pipe — Pipe that runs between the
distribution main in the street and the riser in the case
of multi-storeyed building or the meter in the case of
an individual house.
2.1.11 Service Shut-Off Valve (Isolation Valve)
A device installed outside the premises to cut-off the
main supply of gas from pipeline by the supplier.
2.1.12 Vent Pipe — A safety device to which certain
regulators are connected to evacuate outside gas that
may escape from the normal circuit when some part of
system gets damaged or malfunctions or a safety valve
is open.
3 PRESSURE REGULATIONS
3.1 Pressure regulation is required to economize the
sizing of piping system. Where the pressure of gas
supplied to domestic system or other low pressure gas
piping system in buildings is in excess of the pressure
to be used in the appliance, a gas pressure regulator of
suitable specification shall be installed in service pipe
of each system to prevent excess pressure reaching the
appliance. The pressure regulators to be used can be
from 400 kN/m 2 upstream pressure to 2.1 kN/m 2
for domestic consumers and 10 kN/m 2 , 30 kN/m 2 ,
200 kN/m 2 for commercial consumers, as the case may
be.
3.1.1 In some place the reduction of pressure from
main distribution source of 400 kN/m 2 to intermediate
pressure (say 7 kN/m 2 ) and then to operating pressure
of 2.1 kN/m 2 is achieved.
3.1.2 Whereas in most of the other places the reduction
of pressure from main distribution source of 400 kN/m 2
to directly operating pressure (say 2.1 kN/m 2 , 10 kN/m 2 ,
30 kN/m 2 , 200 kN/m 2 ) is achieved in single stage
pressure reduction.
3.2 If located inside a building, the required regulator
shall comply with the following:
a) If any of the diaphragms of the regulator
ruptures, the gas shall be sent to an outlet vent
pipe made of brass or plastic in order to
ventilate or drain the gas out of the building.
The vent pipe will, however, lead to outer air
about 1 m above the topmost storey of the
building. Means shall be employed to prevent
water from entering this pipe and also to
prevent stoppage of it by insects or other
foreign bodies.
PART 9 PLUMBING SERVICES — SECTION 2 GAS SUPPLY
b) If the gas pressure at the outlet of the regulator
falls below 50 percent of the operating gas
pressure or rises above twice the operating
gas pressure, the gas input to the pressure
regulator shall be cut off.
c) In the event of malfunctioning of this safety
device, a supplementary device shall connect
the low pressure circuit to the outlet circuit
(vent pipe) as soon as the exit pressure reaches
7 kN/m 2 .
3.3 It shall also be ensured by the supply authority
that the calorific value and supply pressure of gas shall
not exceed the values for the type of gas used.
4 SERVICE SHUT-OFF VALVES
4.1 Service shut-off valves shall be installed on all
new services including replacements in a readily
accessible location.
4.2 Service shut-off valves shall be located upstream
of the meter if there is no regulator or upstream of the
regulator, if there is one.
4.2.1 Service shut-off valves shall be located in the
upstream of the meter, if a single regulator is supplying
more than one consumer and each such stream shall
have one additional shut off valve upstream of
regulator.
4.3 All gas services operating at pressure greater than
7 kN/m 2 shall be equipped with an approved service
shut-off valve located on the service pipe outside the
building.
4.4 Underground shut-off valves shall be located in a
covered durable curb box, manhole, vault or stand pipe
which is designed to permit ready operation of the valve
and the covers of which shall be clearly marked 'Gas' .
5 EXISTING WORK
Nothing herein shall prohibit the continued use of
existing system of the gas piping without further
inspection or test, unless the Authority has reason to
believe that defects which make the system dangerous
to life or property exist.
6 RULES FOR TURNING GAS ON
6.1 No person, unless is the employ of the gas
company or having permission from the gas company,
shall turn on the gas at a service shut-off valve or at
any valve that controls the supply of gas to more than
one consumer.
6.2 Gas shall not be turned on at any meter valve
without specific permission from the gas company
or other authority if any of the following conditions
exists:
a) If the gas piping appliances or meter supply
through the meter valve are known to leak or
otherwise to be defective {see 10).
b) If required inspection of the piping or
appliance has not been made.
c) If the gas company or other authority has
requested that the gas be left turned off,
d) If the meter valve is found shut off for some
reason not known to the gas fitter.
The gas shall not be turned on in the event of fire.
6.3 Gas shall not be turned on at any branch line valve
if any of the conditions specified in 6.2 prevails. Where
a branch line valve is found closed, a gas fitter shall
again turn the gas on at such valve only if proper
precautions to prevent leakage are taken and no other
unsafe conditions are created thereby.
6.4 Gas shall not be turned on at either the meter valve
or service line unless all gas keys or valves provided
on all outlets in the piping system are closed or all
outlets in the piping system are capped or plugged.
7 RULES FOR SHUTTING OFF THE GAS
7.1 The gas fitter shall put the gas off to any appliance,
pipe or piping system and shall leave the gas turned
off, until the causes for interrupting the supply has been
removed in any one of the following cases:
a) If ordered to do so by the Authority.
b) If leakage of gas is noted, which appears to
be sufficient to cause fire, explosion or
asphyxiation.
c) If an installation of some gas appliance is
found to be such as to cause a serious hazard
to persons or property.
d) If any condition exists which threatens
interruption of gas supply which may cause
burner outage or otherwise prove dangerous.
7.2 It shall be the duty of the installing agency when
the gas supply is to be turned off to notify all affected
consumers.
7.3 Before turning off the gas at the meter, for the
purpose of installation, repair, replacement or
maintenance of piping or appliance, all burner and pilot
valves on the premises supplied with gas through the
meter shall be turned off and the meter test hand
observed for a sufficient length of time to ascertain
that there is no gas passing through the meter. Where
there is more than one meter on the premises,
precaution shall be exercised to ensure that the
concerned meter is turned off.
8 INSTALLATION OF GAS PIPES
8.1 Installation, repair and replacement of gas piping
NATIONAL BUILDING CODE OF INDIA
or appliances shall be performed only by a qualified
installing agency.
8.2 Piping
8.2.1 Piping shall be of wrought iron, steel, copper or
cast iron when the gas pressure is less than 7kN/m 2 ;
with higher gas pressure use of cast iron shall be
prohibited.
8.2.1.1 SS 316/304/321 Flexible PE coated flexible
pipe in rolls shall be permitted in low pressure system
provided the pipe meets the required standard, to avoid
the bends, fittings and leakages from the joint which
are potential leakage points. Also, reference may be
made to accepted standard [9-2(1)]. Heavy rubber
flexible tube shall be permitted only as direct
connection to burner from appliance valve.
8.2.2 Size of Gas Piping
Gas piping shall be of such size and so installed as to
provide supply of gas sufficient to meet the maximum
demand without undue loss of pressure between the
meter or service regulator when a meter is not provided,
and the appliance(s).
8.2.2.1 The size of gas piping depends upon the
following factors:
a) allowable loss in pressure from meter or
service regulator, when a meter is not
provided, to appliance;
b) maximum consumption to be provided;
c) length of piping and number of fittings; and
d) specific gravity of gas.
8.2.2.2 No gas pipe smaller than 8 mm shall be used.
8.2.3 As far as possible, straight lengths of piping
should be used. Where there are bends in the pipe line,
these should have a radius of at least five times the
diameter of the pipe.
8.2.4 For any thread joint proper sealant shall be used
on male threads only.
8.3 The gas piping shall be of the colour stipulated by
explosive authority to distinguish it from other piping
and the piping shall be painted silver grey with red
band of 150 mm width. The gas pipeline shall be
painted canary yellow in case of natural gas.
8.4 Piping Underground
8.4.1 Protection of Piping
Piping shall be buried to a minimum depth of 1 m or
covered in a manner so as to protect the piping from
physical damage.
8.4.2 Protection against Corrosion
Generally all the piping within the premises where it
has to run on the wall shall be exposed and should not
be in contact with wall to ensure that no corrosion takes
place. Epoxy sealant or polyethylene conduit shall be
used to ensure no contact of pipe with the wall in the
situation of pipe crossing the wall. Under ground or
concealed gas pipeline in contact with earth or other
materials which may corrode the piping shall be
protected against corrosion by application of adequate
corrosion resistant coating backed up by cathodic
protection system.
8.5 The building shall not be weakened by the
installation of any gas piping.
8.6 Gas piping in building shall be supported with
pipe hooks, metal pipe straps, bonds or hangers
suitable for the size of piping and of adequate strength
and quality and located at proper intervals so that the
piping may not be moved accidentally from the
installed position.
8.7 Pipe Entrance to Buildings
Where gas pipe enters a building through a wall or
floor of masonry or concrete, any gas piping or other
piping entering the walls or floors shall be suitably
sealed against the entrance of water/moisture or gas.
Regarding protection of openings in walls or floors,
from fire, reference shall be made to Part 4 'Fire and
Life Safety'.
8.7.1 Piping in Floors
Piping in solid floors, such as concrete, shall be laid in
channels in the floor suitably covered to permit access
to the piping with a minimum damage to the building.
8.7.2 Single pipe without joint shall be used for wall
crossing in any building.
8.8 Gas pipe shall not be bent. Fittings shall be used
when making turns in gas pipe.
8.9 Generally concealed piping shall not be allowed.
However, if it is necessary then it shall be under the 8.4
of underground piping and all protection such as
coating, cathodic protection shall be done.
8.10 A drip shall be prqvided in the gas distribution
system, if the moisture contents in the gas is likely to
reach saturation point at any stretch of pipe line in
the system; a drip shall, however, be provided at any
suitable point in the line of the pipe where condensate
may collect and from where it can be easily removed.
This drip should be so installed as to constitute a trap
where in an accumulation of condensate will shut
off the flow of gas before it will run back into the
meter.
8.10.1 Drip has to be provided in the case of gas
consisting moisture content.
PART 9 PLUMBING SERVICES — SECTION 2 GAS SUPPLY
8.11 Prohibited Devices
No device shall be placed inside the gas piping or
fittings that will reduce the cross-sectional area or
otherwise obstruct the free flow of gas.
8.12 Piping shall be electrically continuous throughout
its length and properly earthed except in stretches
where cathodic protection system is used for protection
against corrosion. It shall not, however, be used to earth
any electrical equipment.
8.12.1 The distance between gas piping and electrical
wiring system shall be at least 60 mm and, where
necessary, they shall be securely fixed to prevent
contact due to movement. The gas piping should run
above the electrical wiring. In this type of installation
in the event of any leakage of natural gas, the gas would
move up (natural gas being lighter than air) and would
not come directly in contact with the electrical wiring.
If the gas to be supplied is heavier than the air then the
gas piping should run below the electrical wiring.
8.13 The distance between the gas piping and steam
piping, if running parallel, shall be at least 150 mm.
The gas piping should preferably run below the steam
piping.
8.14 Piping installation shall be thoroughly gas-tight.
8.15 Smoking shall not be permitted when working
on piping which contains or has contaminated gas.
8.16 Meters shall be installed in such a way that there
shall be no load transfer from the pipeline to the inlet/
outlet of the meter and shall be easily accessible.
9 INSPECTION OF SERVICES
9.1 No person shall use or permit the use of a new
system or an extension of an old system of gas piping
in a building or structure before the same has been
inspected and tested to ensure the tightness of the
system, and a certificate has been issued by the
Authority.
9.1.1 Test of Piping for Tightness
Before any system of gas piping is finally put in service,
it shall be carefully tested to ensure that it is gas-tight.
Where any part of the system is to be enclosed or
concealed, this test should precede the work of closing
in. To test for tightness the piping may be filled with
city gas, air or inert gas but not with any other gas or
liquid. In no case shall oxygen be used. The piping
shall stand a pressure of at least 20 kN/m 2 measured
with a manometer or slope gauge, for a period of
not less than 10 min without showing any drop in
pressure.
9.1.2 When the gas pressure exceeds 7 kN/m 2 , the
piping shall withstand a pressure of 0.6 MN/m 2 for 4 h.
(This test is for piping designed for working pressure
less than 0.4 MN/m 2 .)
9.2 The Authority shall, within a reasonable time after
being requested to do so, inspect and test a system of
gas piping that is ready for such inspection and test,
and if the work is found satisfactory and test
requirements are complied with, it shall issue the
certificate.
10 LEAKAGE CHECK
10.1 Before turning gas under pressure into any piping;
all openings from which gas may escape shall be
closed,
10.2 Checking for Gas Leakage
No matches, flame or other sources of ignition shall
be employed to check for gas leakage from meters,
piping or appliances. Checking for gas leakage with
soap and water solution is recommended.
10.3 Use of Lights
Artificial illumination used in connection with a search
of gas leakage shall be restricted to electric hand flash
lights (preferably of the safety type) or approved safety
lamps. In searching for leaks, electric switches should
not be operated. If electric lights are already turned
on, they should not be turned off.
10.4 Checking for Leakage with Meter
Immediately after turning gas into the piping, the
system shall be checked to ascertain that no gas is
escaping. This may be done by carefully watching the
test dial of the meter to determine whether gas is
passing through the meter. In no case should a leakage
test be made using a gas meter unless immediately prior
to the test it has been determined that the meter is in
operating condition.
10.5 Checking of Leakage Without Using a Meter
This may be done by attaching to an appliance, orifice
or a manometer or equivalent device and momentarily
turning on the gas supply and deserving the gauging
device for pressure drop witji the gas supply shut-off.
No discernible drop in pressure shall occur during a
period of 3 min.
10.6 After piping has been checked, all gas piping shall
be fully purged. Piping shall not be purged into the
combustion chamber of an appliance. A suggested
method for purging the gas piping to an appliance is to
disconnect the pilot piping at the outlet of the pilot
valve.
10.7 After the gas piping has been effectively purged,
all appliances shall be purged and the pilots lighted.
8
NATIONAL BUILDING CODE OF INDIA
10.8 In addition to the checking of gas leakage with
soap and water solution, a suitable gas detector is also
recommended for use.
11 USE OF LIQUEFIED PETROLEUM GAS
11.1 The cylinders used for the storage and
transportation of liquefied petroleum gas (LPG) shall
conform to accepted standards [9-2(2)] approved by
the statutory authority.
11.2 The handing, use, storage and transportation of
liquefied petroleum gas in cylinders exceeding 500 ml
water capacity shall be done in accordance with good
practice [9-2(3)].
11.3 LPG Cylinder Installation
The following recommendations apply to installation
in commercial, industrial, educational and institutional
premises.
11.3.1 General Recommendations
11.3.1.1 Those responsible for the installation of
cylinders, equipment and piping should understand the
characteristics of LPG and be trained in good practice
of handling, installing and maintaining installations.
11.3.1.2 The jointing compound used at different
joints in the system shall be decided by the Qualified
Installing Agency. Hemp and similar materials shall
not be used at the joint. In any joint in which the thread
provides a gas-tight seal, jointing compound shall be
used only on the male thread.
11.3.1.3 Fire extinguishers of dry powder type or
carbon dioxide type conforming to accepted standards
[9-2(4)] shall be provided in places where LPG cylinder
installations are situated and shall be located near such
installations. Two buckets filled with sand and two with
water shall also be installed nearby. The number, type
and size of the fire extinguishers shall be as follows:
Number Type Capacity
a) For installations
with LPG 40 kg
to 200 kg
b) For installations
with LPG more
than 200 kg and
up to 320 kg
c) For installations
with LPG more
than 320 kg and
up to 1 000 kg
Dry 10 kg
Powder
Dry 10 kg
powder
Dry 10 kg
powder
For electrical installations, one number C0 2 fire
extinguisher (4.5 kg capacity) shall be provided.
11.3.1.4 Liquefied petroleum gas shall not be
transferred from the cylinders in which it is received
to any other container.
11.3.2 Cylinder Location
11.3.2.1 Stationary installations
a) Stationary installation not exceeding 40 kg of
LPG may be installed indoors on any floor. It
is recommended to have a minimum floor
area of 5 m 2 for such an installation.
b) Stationary installations each not exceeding
40 kg of LPG may be installed indoors on any
floor within the same workspace provided
the minimum distance between two such
installations is 3 m, the proportion of such
installations to floor area is one installation
per 5 m 2 and the aggregate quantity of gas of
all such installations does not exceed 200 kg.
c) Stationary installation not exceeding 80 kg of
LPG may be installed indoors on any floor
provided the floor area for such an installation
is not less than 12 m 2 .
d) Stationary installations each not exceeding
80 kg of LPG may be installed indoors on any
floor and within the same workspace provided
the minimum distance between two such
installations is 3 m, the proportion of such
installations to floor area is one installation
per 12 m 2 and the aggregate quantity of gas
of all such installations does not exceed
200 kg.
e) Stationary installation not exceeding 320 kg
of LPG may be installed indoors in an
enclosed section of a building or a room
reserved exclusively for this purpose and
ventilated at low level directly to the outside
air.
f) Stationary installation above 320 kg [200 kg
in case provision as in (e) is not possible] but
not exceed 1 000 kg shall be installed outdoors
on ground level only. A minimum distance
of 3 m shall be maintained between an
installation and any building, public place,
roadways, and other surroundings. The
installation shall be protected from excessive
weathering by sun, rain, etc, and from
tampering by unauthorized persons. A lean-
to-roof with expanded metal on angle-iron
framework on the sides is considered suitable
for this purpose. In any case, adequate
ventilation at ground level to the outside air
shall be provided. The distance between any
two such installations shall be 3 m unless
separated by a leakproof wall of fire-resistant
PART 9 PLUMBING SERVICES — SECTION 2 GAS SUPPLY
material up to at least 1 m above the height of
the manifold valve,
g) The position of the cylinders shall facilitate:
1) changing and quick removal of any
cylinder in case of necessity, and
2) access to cylinder valve connections and
regulating devices.
h) Cylinders shall be installed upright with the
valves uppermost.
j) Cylinder shall not be installed or used below
ground level in cellars or basements.
k) Cylinders containing more than 20 kg of gas
shall not be located on floors above ground
level.
m) Cylinders shall be located on a concrete or
brick floor, preferably raised in case of
outdoor installations.
n) Cylinders shall not be placed close to steam
pipes or any other source of heat and shall be
protected from the weather and direct sun's
heat. Cylinders shall be placed at a distance
of 3 m away from any other source of heat
which is likely to raise the temperature of
cylinders above the room temperature unless
separated by metal sheet or masonry partition.
p) When cylinders are being connected or
disconnected, there shall be no open flame or
similar source of ignition in the vicinity; and
smoking shall be prohibited.
q) Cylinders shall not be installed at a place
where they are likely to cause an obstruction,
to be damaged or to be exposed to conditions
likely to affect their safety.
r) In order to prevent the hazardous collection
of gas, cylinders shall be placed at least 1 m
away from culverts, depressions, or openings
leading to below ground level compartment,
and drains.
s) Cylinders which have safety relief valves or
similar devices incorporated in them shall be
so positioned that if the relief device operates,
escaping gas is not hazardous.
11.3.2.2 Portable installations
When portability of cylinders is necessary the
following requirements shall be fulfilled:
a) The sum total capacity of the cylinders
connected to each manifold shall not exceed
80 kg of LPG. The total quantity of gas thus
installed in a workspace shall not exceed
200 kg.
b) If cylinders are mounted on a trolley shall be
stable. Where necessary, the cylinders shall
be secured to prevent them from falling.
c) The regulator shall be connected directly to
the cylinder valve or to a manifold which shall
be connected to the cylinder valves by means
of rigid connections to give adequate support
to the regulator. The only exception to this
requirement is where cylinders are mounted
on a trolley and the manifold is rigidly
supported on the trolley. In such a case
flexible or semi-flexible connections may be
used between the cylinder valves and the
manifold but not between the manifold and
the regulator.
d) At any time the total quantity of gas at
portable installations shall be in proportion
to the floor area as specified in 11.3.2.1(a)
to 11.3.2.1(f).
e) At any time the provisions at 11.3.2.1 shall
be ensured for all installations.
11.3.3 Cylinder Manifolds
11.3.3.1 All materials, fittings, etc, used in cylinder
manifold systems shall comply with the distributing
company's stipulations.
11.3.3.2 The individual component parts of manifolds,
that is, piping, fittings, pigtails, etc, which are subject
to cylinder pressure shall be capable of withstanding a
test pressure without bursting of 2.5 N/mm 2 or one
and a half times the maximum pressure corresponding
in the maximum assessed temperature of the cylinder,
whichever is more.
11.3.3.3 Where cylinder installations are made up with
service and reserve batteries of cylinders, suitable
change-over devices or valves shall be incorporated
in the manifold header to prevent undue escape of the
gas when cylinders are changed.
11.3.3.4 If pressure regulators, manifold headers,
automatic change-over devices, etc, are connected to
cylinders by semi-flexible connectors, they shall be
rigidly supported. Copper tube pigtails are considered
to be flexible or semi-flexible connectors for this
purpose.
11.3.3.5 Suitable line shut-off valves shall be fitted
for each appliance or burner when more than one
appliance is connected to the gas supply. Both ends of
the connection to portable appliances shall be securely
attached by means of clips. Hose shall be of a type
resistant to liquefied petroleum gas.
11.3.3.6 It is recommended that joints in manifold
headers which do not have to be taken in normal use
should be welded or brazed using a material and which
shall have a melting point of at least 540°C.
11.3.3.7 All joints between manifold headers and
cylinder connectors shall be readily accessible.
10
NATIONAL BUILDING CODE OF INDIA
11.3.4 Pressure Regulators
11.3.4.1 Pressure regulators and other devices used
to control the gas shall comply with the distributing
company's stipulations and accepted standards
[9-2(5)].
11.3.4.2 Pressure regulator fitted with a safety valve
shall be either:
a) installed in the open air, or
b) vented to the open by means of a metal vent
pipe connected to the safety valve outlet.
11.3.4.3 Care shall be taken that safety valve outlets
do not become choked with dust or other foreign
matter.
11.3.4.4 If the regulator is fitted with a relief valve,
care should be taken in positioning the regulator to
avoid unnecessary hazards if the relief valve functions.
1 1.3.4.5 Pressure regulators and other control devices
shall be adequately supported.
11.3.5 Instructions to Consumers
A handbook containing all instructions with regard to
the following aspects shall be supplied by the supplier
to the consumers:
a) operation of the whole system;
b) how to recognize gas leaks;
c) action to be taken in case of leakage;
d) action to be taken in case of fire; and
e) action to be taken in case of damage to, or
failure of any part of the installation.
11.3.6 For detailed information regarding installation
of LPG cylinders in commercial, industrial, educational
and institutional premises, reference may be made to
good practice [9-2(6)].
11.4 LPG Bulk Storage Installations
11.4.0 The following recommendations apply to LPG
bulk storage installations where storage tanks over
450 litres water capacity are used at industrial,
commercial and domestic consumers' premises.
The maximum capacity of an individual tank and group
of tanks at industrial, commercial and domestic
premises shall be as follows:
Premises Maximum Water Maximum Water
Industrial
Commercial
Domestic
Capacity of an
Individual Tank
1
130 000
40 000
20 000
Capacity of
Group of Tanks,
1
260 000
80 000
80 000
11.4.1 Location and Spacing of Storage Tanks
11.4.1.1 Storage tanks shall be located outside the
buildings and shall not be installed one above the other.
11.4.1.2 Each individual tank shall be located with
respect to the nearest important building or group of
buildings or line of adjoining property which may be
built in accordance with Table 1. The distances given
refer to the horizontal distance in plan between the
nearest point of the storage tank and building/property
line.
11.4.1.3 In heivily populated or congested areas the
authority may determine the need for other reasonable
protective methods to be taken, such as provision of
fire walls, etc. If fire walls are to be provided, the
authority may determine the extent to which the safety
distances for above ground tanks may be reduced.
11.4.1.4 No LPG tank(s) shall be located within the
bunded enclosures of any petroleum installation. The
minimum distance of separation between LPG storage
tanks and any petroleum installation shall be as
prescribed under the Petroleum Rules, 1976 or as
specified in Table 1 whichever is more.
11.4.1.5 The number of storage tanks in one storage
installation shall not exceed six. In case there are more
than one storage installations, the safety distance
between two installations shall be the same as the
distance between the tanks and the property line in
accordance with Table 1 .
11.4.2 Bunding
Since LPG is heavier than air, storage tank shall not
be enclosed within bund walls. The accumulation of
flammable liquid under LPG tanks shall be prevented
by suitably slopping the ground.
11.4.3 Protection
11.4.3.1 To prevent trespassing or tampering, the area
which includes tanks, direct fired vapourisers, pumping
equipment and loading and unloading facilities shall
be enclosed by an industrial type fence at least 2 m
high along the perimeter of the safety zone. Any fence
shall have atleast two means of exit. Gates shall open
outwards and shall not be self-locking.
11.4.3.2 When damage to LPG systems from the LPG
tank lorry is a possibility, precautions against such
damage shall be taken.
11.4.3.3 Underground tanks shall be protected from
above ground loading by providing a suitable curb to
prevent a possible accidental damage to the tank and
its fittings by LPG tank lorry.
11.4.4 Grass and Weed Removal
Road ignitable material, such as weeds, long grass or
any combustible material shall be removed from an
PART 9 PLUMBING SERVICES — SECTION 2 GAS SUPPLY
11
Table 1 Minimum Safety Distances
(Clauses 11.4.1.2, \) AAA and 11.4.1.5)
Si LPG Storage Water Capacity of
No. Individual Tank
1
(1) (2)
i) Up to 2 000
ii ) Above 2 000 and up to ! 000
i i i ) Above 1 000 and up lo 20 000
i\ i Above 20 000 and up to 40 000 adjacent
v) Above 40 000 and above adjacent
Distance from Building/Property Line
Distance between Tanks
Above Ground
in
(3)
Under Ground
in
(4)
Above Ground
(5)
Under Ground
in
(6)
5
10
15
20
30
5
7.5
10
15
15
1
1
1.5
2
1.5
1.5
1.5
0.25 dia of vessel
or
1 .5 in. Min
0.25 dia of vessel
or
! .5 nrv Min
MOTE — If the aggregate water capacity of a multi-tank installation is 40 000 litres or greater, the above minimum safety distances
shall apply to the aggregate storage capacity rather than the capacity per individual storage tank.
area within 3 m from the shell of any LPG lank of up
to 2 000 litres water capacity, and within 6 m from the
shell of larger tanks. If weedkillers are used, chemicals
which are a potential source of fire hazard shall not be
selected for this purpose.
I i.4.5 Warning Signs
No smoking or naked flames shall be permitted within
the safety zone of the installation. Prominent notices
to this effect shall be posted at access point.
11.4.6 Fire Protection
The possibility of a major fire outbreak, leading to
direct flame impingement of the storage tank, shall be
minimized by sound engineering in plant design and
layout, good operating practice, and proper education
and training of personnel on both routine operations
and on action to be taken in an emergency.
11.4.6.1 Water supply
Provision shall be made for an adequate supply of water
and fire protection in the storage area according to the
local hoses and mobile equipment, fixed monitors or
by fixed spray systems which may be automatic.
Control of water flow should be possible from outside
any danger area.
11.4.6.2 Fire extinguishers
At least two dry chemical powder type fire extinguishers
of 10 kg capacity each, conforming to the quality
requirements in accordance with the accepted standards
[9-2(7)], each shall be installed at points of access to
the storage installations.
11.4.7 For detailed information regarding LPG bulk
storage installations reference may be made to good
practice [9-2(8)].
LIST OF STANDARDS
The following list records those standards which are
acceptable as 'good practice' and 'accepted standards'
in the fulfillment of the requirements of the Code. The
latest version of a standard shall be adopted at the time
of enforcement of the Code. The standards listed may
be used by the Authority as a guide in conformance
with the requirements of the referred clauses in the
Code,
Title
Specification for polyethylene
pipe for the supply gaseous fuel
Specification for welded low
1 992 carbon steel cylinders exceeding
5 litre water capacity for low
IS No.
i)
14885 :200
7)
3196
(Part 1): f
IS No.
7142: 1995
(3)
8198
(Part 5): 1984
Title
pressure liquefiable gases:
Part 1 Cylinders for liquefied
petroleum gases (LPG) (fourth
revision)
Specification for welded low
carbon steel cylinders for low
pressure liquefiable gases not
exceeding 5 litre water capacity
(first revision)
Code of practice for steel
cylinders for compressed gases:
Part 5 Liquefied petroleum gas
(LPG) (first revision)
NATIONAL BUILDING CODE OF INDIA
IS No.
(4) 2171 : 1999
2878 : 1986
(5) 4784: 1968
4785 : 1968
4786 : 1968
Title
Specification for portable fire
extinguisher, dry powder
(cartridge type) (third revision)
Specification for fire
extinguisher, carbon dioxide
type (portable and trolley
mounted) (second revision)
Specification for low pressure
regulators for use with butane
gases
Specification for low pressure
regulators for use with propane gas
Specification for variable high
pressure regulators for use with
liquefied petroleum gas
(6)
IS No.
6044
(Part 1)
2000
(7) 2171 : 1999
(8) 6044
(Part 2) : 2001
Title
Code of practice for liquefied
petroleum gas storage
installations: Part 1 Commercial
and industrial cylinder
installations (first revision)
Specification for portable
fire extinguishers, dry
powder (cartridge type) (third
revision)
Code of practice for liquefied
petroleum gas storage
installations: Part 2 Commercial,
industrial and domestic bulk
storage installations (first
revision)
PART 9 PLUMBING SERVICES — SECTION 2 GAS SUPPLY
13
NATIONAL BUILDING CODE OF INDIA
PART 10 LANDSCAPING, SIGNS AND OUTDOOR
DISPLAY STRUCTURES
Section 1 Landscape Planning and Design
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 PERMIT
4 PROTECTION OF LANDSCAPE DURING CONSTRUCTION
5 SOIL AND WATER CONSERVATION
6 EARTH SLOPES AND GRADING REQUIREMENTS
7 PLANTING DESIGN CONSIDERATIONS
8 SPECIFICATIONS FOR PLANTING WORKS
9 SERVICE UTILITIES IN LANDSCAPE
10 PAVED SURFACES IN EXTERNAL AREAS
11 STREET FURNITURE
5
5
6
8
9
12
13
20
24
26
26
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
This Part of the Code was first published in 1970 and subsequently revised in 1983, and covered provisions
relating to only signs and outdoor display structures. In this revision, this Part has been sub-divided into two
sections as follows by including a new section on landscaping:
Section 1 Landscape planning and design
Section 2 Signs and outdoor display structures
This Section covers the requirement of landscape planning and design with the aim of improving quality of
outdoor built environment and protection of the land and its resources. With growing urban development and
environmental degradation it has become imperative to determine landscape design parameters, and also provide
rules, regulations, controls and procedures for the protection, preservation and modification of surrounding
environment. A brief clause on street furniture has also been introduced in this Section.
The components of landscape design and external development were earlier covered in the Code in its various
Parts/Sections but a comprehensive treatment has been given in this new Section in this revision.
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 1 LANDSCAPE...
NATIONAL BUILDING CODE OF INDIA
PART 10 LANDSCAPING, SIGNS AND OUTDOOR
DISPLAY STRUCTURES
Section 1 Landscape Planning and Design
1 SCOPE
This Section covers requirements of landscape
planning and design with the view to promoting quality
of outdoor built environment and protection of land
and its resources.
2 TERMINOLOGY
2.0 For the purpose of this Section, the following
definitions shall apply.
2.1 Avenue — A wide road or pathway lined with
trees on either sides.
2.2 Buffer — The use of landscape to curtail view,
sound or dust with plants or earth berms, wall, or any
such element.
2.3 Climber (Creeper/Vine) — A non-supporting
plant, woody or herbaceous, which clings to a wall,
trellis or other structures as it grows upward.
2.4 Columnar — A slender, upright plant form.
2.5 Contour — The form of the land, existing or
proposed; a part of the topography, indicated by map
lines at intervals as desired, to understand the landform
clearly. The contour line though imaginary, indicates
continuous elevation above mean sea level or an
assumed datum line.
2.6 Contour Interval — The difference in elevation
or the vertical distance measured between consecutive
contour lines.
2.7 Egress — A way out, or exit.
2.8 Elevation — A contour line or notation of relative
altitude, useful in plotting existing or proposed feature.
2.9 Exotic — A plant that is not native to the area in
which it is planted.
2.10 Fencing — A barrier of plant or construction
material used to set off the boundary of an area and to
restrict visual or physical passage in or out of it.
2.11 Foliage — The collective leaves of a plant or plants.
2.12 Geo-textile — Any permeable textile (natural or
synthetic) used with foundation, soil, rock, earth or
any other geotechnical engineering-related material as
an integral part of a human made project, structure or
system.
2.13 Grade — The slope or lay of the land as indicated
by a related series of elevations.
2.13.1 Natural Grade — Grade consisting of contours
of unmodified natural landform.
2.13.2 Finished Grade — Grade accomplished after
landscape features are installed and completed as
shown on plaaas proposed contours.
2.14 Gradient — The degree of slope of a pipe invert
or road or land surface. The gradient is a measure of
the slope height as related to its base. The slope is
expressed in terms of percentage or ratio.
2.15 Grading — The cutting and/or filling of earth
to establish smooth finish contours for a landscape
construction project. Grading facilitates good drainage
and sculpts land to suit the intent of landscape design.
2.16 Grasses — Plants that characteristically have
joint stems, sheaths and narrow blades (leaves).
2.17 Groundcover — The planting material that
forms a carpet of low height; these low-growing plants
are usually installed as the final part of landscape
construction.
2.18 Hard Landscape — Civil work component of
landscape architecture such as pavement, walkways,
roads, retaining walls, sculpture, street amenities,
fountains and other built environment.
2.19 Hardy Plant — Plants that can withstand harsh
temperature variations, pollution, dust, extreme soil
conditions, and minimal water requirements and the
likes. These plants have ability to remain dormant in
such conditions and survive.
2.20 Hedge — Number of shrubs or trees (often
similar species) planted closely together in a line. A
hedge may be pruned to shape or allowed to grow to
assume its natural shape.
2.21 Herb — An annual plant with a non-woody or
fleshy structure. Certain herbs are highly useful for
cooking or of high medicinal value.
2.22 Ingress — A way in, or entrance.
2.23 Invert — The low inside point of a pipe, culvert,
or channel.
2.24 Kerb — A concrete or stone edging along a
pathway or road often constructed with a channel to
guide the flow of storm water and thereby serving dual
purpose.
2.25 Mound — A small hill or bank of earth,
developed as a characteristic feature in landscape.
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 1 LANDSCAPE...
2.26 Native — A plant indigenous to a particular
locale.
2.27 Screen — A vegetative or constructed hedge or
fence used to block wind, undesirable views, noise,
glare and the like, as part of in landscape design; also
known as 'screen planting' and 'buffer plantation'.
2.28 Sediment — The product of erosion processes;
the solid material, both mineral and organic, that is in
suspension, is being transported or has been moved
from its site of origin by air, water, gravity or ice.
2.29 Shrub — A woody plant of low to medium
height, deciduous or evergreen, generally having many
stem.
2.30 Soft Landscape — The natural elements in
landscape design, such as plant materials and the soil
itself.
2.31 Spot Elevation — In surveying and contour
layout, an existing or proposed elevation noted as a
dot on the plan.
2.32 Street/Outdoor Furniture — Items of furnishing
in outdoor landscape.
2.33 Swale — A linear wide and shallow depression
used to temporarily store, route or filter runoff. A swale
may be grassed or lined.
2.34 Topsoil — The uppermost layer of the soil.
2.35 Transplanting — Moving a plant from its place
of origin to another location.
2.36 Tree — A woody plant, generally taller than
2.00 m, with a well-distinguished trunk or trunks below
the leaf crown.
2.36.1 Deciduous Tree — Tree that sheds all its leaves
in autumn or in dry season.
2.36.2 Evergreen Tree — Tree that remains green for
most part of the year and sheds leave slowly throughout
the year.
2.37 Tree Grate — A metal grille, installed at the
base of a tree otherwise surrounded by pavement, that
allows the free passage of air, water, and nutrients to
the tree root, but does not interfere with the foot traffic.
2.38 Tree/Plant Guard — The protection constructed
around a tree to deter vandalism and help to prevent
damage. It could be made of metal, bamboo or concrete
or the like.
3 PERMIT
3.1 Application for Licence or Permit and Required
Drawings
Any development project for which a permit or licence
is required, shall make application to the Authority on
the prescribed form containing such particulars as the
Authority may require. The form shall be signed by
the owner and shall include the information given in 3.2
to 3.4. For various aspects of obtaining the permit, etc
reference shall be made to Part 2 'Administration'.
3.2 Site Plan Contents and Specifications
3.2.1 Site Plan
The site plan to be submitted with the application for
permit shall be drawn to a scale of not less than 1 in
500 for a site up to one hectare and not le^s than 1 in
1 000 for site more than 10 hectare, the following
information shall be provided in addition to
requirements for Site Plan as stated in Part 2
'Administration 1 :
a) Existing and proposed topographic contours
at interval not exceeding 50 cm and/or spot
elevations as pertinent and Bench Mark of site
with reference to the City Datum relative to
the Mean Sea Level.
b) Limits of the 100 year flood plain and water
surface elevation (when applicable).
c) Location of existing major physical features,
such as railway track, drainage ways etc.
d) Location of service utilities adjacent to the
project with relevant top and invert levels
clearly indicated.
e) Point of egress and ingress including locations
and width of road.
f) Fully dimensioned loading spaces and
maneuvering areas.
g) Parking including, location, parking spaces,
size and number, and typical parking space
details for both handicapped and standard
spaces.
h) Vehicular, bicycle, pedestrian and handicapped
circulation clearly identified.
j) Detail for parking areas including type of
lighting, material for paving, and security
rooms, rest rooms; and type of directional
signage etc.
k) Drainage system, proposed finish ground
elevations and finish grades,
m) Location of proposed fire hydrant points,
n) Location and dimension of fire lanes,
p) Proposed lighting layout,
q) Landscape irrigation points and source of
water,
r) Fences, walls, or vegetation for screening by
type, material, height, location, and spacing.
s) Location of proposed street furniture.
NATIONAL BUILDING CODE OF INDIA
t) Refuse container location, size, and access,
v, i^ocation, type, size, and height of existing
ano proposed signage.
w) List of existing trees with botanical and
common names and height of the tree (see
4.1.2 for plant material schedule),
x) Prior approvals.
3.3 Landscape Pian Contents and Specifications
Landscape pian and drawings shall consist of the olans
and details as ?iven in -W1 m Tl d
Tree
No.
chnll Y\f* Af*mc*rr-at&A ^looi-ln ( ^^^ ^./^^ /I 1 1\
A concept plan of scale not less than I in i 000
indicating the intent of the design with respect
to the functions for various parts of the
scheme should be included.
Table 1 Plant Materia! Schedule
( r^i n i <-»\
Code
(I) (2)
Botanical
Name
(3)
Common
Name
(4)
Quantity
(5)
3.3 A Grading Plan
The prndino nlan tn hp cuhmitt^H \iritU tU& a««i;^^i;^«
for nerinit chilli hp r\r<A\\?n tn q ct-oIpk /^-f rm* 1^ ( . ( -. fk^r, i
- r - *-.™.* «_^ ^*, »" >i iw tl o^cii^ v/i iiv/l iv^-k-) man i
in SOD for a citf nn tr\ 1 O ^pMq^ ^ n A rm+ i af ,r *v,«„ i :„
.-. ~ ~ ., , vi „ tJit ^ M p lv/ iv uvviuiv. unu nyji i\^a?> Miail ( III
! 000 fnr tilf» mnrp thou ID k^^t^t-a. /„,.,, „1„^ a *>\ TU„
ori-iH ino n]'jn
tprlim^nf-itinn ^/-i»-i <-»-,^1 n«^ «!,-,,-. ™. ^ , j : __ _
"v U i„iv«uuuwii vuimui ciiivj auu IIICUSUIC?* UUI nig
f'nnt'l r\-\C*t\{-\r\ t/^i rvrai ;ant r, ^ I 1 ^*.^ ^, 1 ,- J „ t ... _ .
v,wuoi.Lu^iiwij w^ pi^vuu ^>vjii ciwiuii, aiiu aisu waier
3.3.2 Planting Pian
a lie planting plan shall be drawn to a scale of not less
Ulan j in ^w iui a sue up lu one neciare ana not less
tnan I m 500 for site more than 10 hectare with part
plans at 1 in 200 of two of the design areas. Planting
plan should include plant material schedule as shown
in Table 1 . The planting pian and landscape pian must
show identical information to avoid conflict between
both plans. The planting plan shall include the layouts
as given below drawn to the scale:
a) Location of proposed trees, shrubs, ground
covers and lawn area indicated clearly with
appropriate symbols and legend.
The <ii7P nf nlnnl- materia} ir»Hi/-«otwl in tU^
,..^ J „ ^, ^ jjikiii,. tuuiviiui IIIUIVUI^U 111 LH\^
Hr n wi n a chnnlH h*=* el-i^\i/n no Ai^m^t^r- ^f
v " j "-y; iv/i viw\^ unu opiv^cnj iv^i .iiiiuus emu
trrAiin^ ^AiiAr T\*/,^ 1/,-w^n ~~~.*, + U ,«,:il 1
^iv^ujiu tuvu. x ww jcais glUVVLll Will UC
consiuereva as iUu maturity size ior Snruus and
b)
^iuuhu luvck> auu icn ^ycais giuwin will Oe
CJ
me tsotanical name could be indicated as a
symbol on the main drawing (for example
Deionix regia as Dr). Plant names should to
be tabulated in alphabetical order under heads
Trees, Shrubs, Groundcovers, Climbers and
Grass.
d) Functional attributes and growth pattern
tabulation to be attached as Table 2, as an
annex.
e) All existing vegetation shall be marked on the
landscaDe nlan and areas designated for
Table 2 Plant Material Schedule Showing
Functional Attributes and Growth
Pattern of Each Plant
[Clause 3.3.2(d)]
si
D>nJ».. nn t 1? *
ivcicTdiii rcaiuit)
Bescripiion
No.
Plant -1
(D
(2)
(3)
i)
Botanical name
in
Corninon name
iii)
Plant code
iv)
Type (Evergreen/Deciduous)
V)
Height
y 1/
vii)
Form of Tree
viii)
Flower colour
IX)
Seasonal duration
*;
zAjne (runctionai AttriDutes)
xi)
Characteristics
xii)
Function
xiii)
Remarks
3.3.3 Irrigation Plan
The irrigation plan shall be drawn to a scale of not less
than 1 in 500 for a site up to one hectare and not less
than 1 in 1 000 for site more than one hectare. The
Plan shall include the following information:
a) The source of irrigation water.
b) Type of water conserving irrigation systems
proposed differentiating between systems for
different water use zones on the site.
c) Extent of supplementary irrigation provided
by water harvesting measures.
H 1 ! ArrnnaPlDPnt rif ll\/Hr<intc r\r enri nV-\t*rc
jnHir'ritina Irvr-ati^in r\t\A h/n«
til IJ pivfll
3.3.4 Construction Details
Construction details, specifications and methods used
for the following landscape elements are to be included
where annlicahle.:
PART 10 LANDSCAPING. SIGNS AND OUTDOOR nTSPTAV«TRlirTiT»F« cvr-nnN i t AMr>e/-ADir
a) All paved areas for pedestrian and vehicular
use, including edges, kerbs, bumper stops,
steps, ramps, planters, railings or other
protective devices; provision for wheel chair
access and movement; Tree protection with
tree grating, tree guard, etc.
b) Boundary wall, fence, retaining wall, etc.
c) Structures in landscape such as gatehouses,
kiosks, toilets, pergolas, space frame, pools,
ponds, water bodies, any other special
features, etc.
d) Site utilities such as stormwater drains,
manholes, catch basins, outdoor lighting
fixtures, electric feeder pillars, junction box,
fire hydrant, garbage collection points, litter
bins, etc.
e) Outdoor signage and street furniture.
f) Play equipment and tot lots where appropriate.
g) Any other relevant detail or information.
4 PROTECTION OF LANDSCAPE DURING
CONSTRUCTION
4.0 Development projects involve disturbance to the
existing soil conditions, removal of existing trees and
overall change in the microclimate and drainage
pattern. Measures to minimize hazardous effects should
be put into effect as explained below.
4.1 Pre-Construction Measures
Measures for the prevention of soil erosion, sediment
control and management of storm water shall be
implemented as given in 4.1.1 to 4.1.5.
4.1.1 Timing of Construction
Construction work and erosion control applications
shall be scheduled and sequenced during dry weather
periods when the potential for erosion is the lowest.
Slope protection techniques to control erosion shall
be used when construction during wet season is
unavoidable. Sedimentation collection systems,
drainage systems, and runoff diversion devices shall
be installed before construction activity. The
Landscape Architect/Architect/Engineer-in-charge
shall monitor the site conditions and progress of work
and schedule appropriate timing and sequencing of
construction.
4.1.2 Preservation of Existing Vegetation
4.1.2.1 Protection of existing vegetation (including
trees, shrubs, grasses and other plants) where possible,
by preventing disturbance or damage to specified areas
during construction is recommended. This practice
minimizes the amount of bare soil exposed to erosive
forces. All existing vegetation shall be marked on a site
survey plan. A tree survey in prescribed format shall be
carried out as indicated in Table 3. The landscape plan
should indicate trees, which have been preserved, and
also those, which had to be transplanted or removed
clearly differentiating between these three categories.
Table 3 Plant Material Schedule for
Tree Survey
(Clause 4.1 2 A)
Tree Botanical Common Girth Height Spread Condition
No. Name Name
(1)
(2)
(3)
(4) (5)
(6)
(7)
4.1.2.2 Trees retained on the project site shall be
protected during the construction period by following
measures:
a) Damage to roots shall be prevented during
trenching, placing backfill, driving or parking
heavy equipment, dumping of trash, oil, paint,
and other materials detrimental to plant health
by restricting these activities to outside the
area of the canopy of the tree.
b) Trees will not be used for support; their trunks
shall not be damaged by cutting and carving
or by nailing posters, advertisements or other
material.
c) Lighting of fires or carrying out heat or gas
emitting construction activity within the
ground, covered by canopy of the tree shall
not be permitted.
d) Young trees or saplings identified for
preservation (height less than 2.00 m, 0. 10 m
trunk girth at 1.00 m height from finish
ground, 2.00 m crown diameter) within the
construction site have to be protected using
tree guards of approved specification.
e) Existing drainage patterns through or into any
preservation area shall not be modified unless
specifically directed by the Landscape
Architect/Architect/Engineer-in-charge.
f) Existing grades shall be maintained around
existing vegetatiori and lowering or raising
the levels around the vegetation is not allowed
unless specifically directed by the Landscape
Architect/Architect/Engineer-in-charge.
g) Maintenance activities shall be performed as
needed to ensure that the vegetation remains
healthy.
h) The preserved vegetated area shall be
inspected by the Landscape Architect/
Architect/Engineer-in-charge at regular
intervals so that they remain undisturbed. The
8
NATIONAL BUILDING CODE OF INDIA
date of inspection, type of maintenance or
restorative action followed shall be recorded
in the logbook.
4.1.3 Staging Areas
Measures shall be followed for collecting runoff from
construction areas and material storage sites; diverting
water flow away from such polluted areas, so that
pollutants do not mix with storm water runoff from
undisturbed areas.
Temporary drainage channels, perimeter dike/swale,
etc shall be constructed to carry the pollutant-laden
water directly to treatment device or facility. The plan
shall indicate how the above is accomplished on site,
well in advance of the commencing of the construction
activity.
4.1.4 Preservation of Topsoil
Topsoil removal and preservation shall be mandatory
for development projects larger than 1.00 hectare.
Topsoil shall be stripped to a depth of 200 mm from
areas proposed to be occupied by buildings, roads,
paved areas and external services. Topsoil is rich in
organic content and is essential to establish new
vegetation. It shall be stockpiled to a height of 400 mm
in designated areas and shall be re-applied to site during
plantation of the proposed vegetation. Topsoil shall
be separated from sub-soil debris and stones larger than
50 mm diameter. The stored topsoil may be used as
finished grade for planting areas.
4.1.5 Spill Prevention and Control
Spill prevention and control plans shall be made,
clearly stating measures to stop the source of the spill,
to contain the spill, to dispose the contaminated
material and hazardous wastes, and stating designation
of personnel trained to prevent and control spills.
Hazardous wastes include pesticides, paints, cleaners,
petroleum products, fertilizers and solvents.
4.2 Measures During Construction
During construction soil becomes unconsolidated due
to removal of stabilizing material such as vegetation
and disturbance of stabilized existing grade resulting
in loss of topsoil and also deposition in undesirable
places. A soil erosion and sedimentation control plan
to be prepared prior to construction. The soil erosion,
sediment control and storm water practices should be
considered whilst construction is proceeding, in
accordance with 4.2.1 to 4.2.4.
4.2.1 Sedimentation Basin
A temporary dam or basin at the lowest point of the
site has to be constructed for collecting, trapping and
storing sediment produced by the construction
activities, together with a flow detention facility for
reducing peak runoff rates. This would allow most of
the sediments to settle before the runoff is directed
towards the outfall.
4.2.2 Contour Trenching
Contour trenching is an earth embankment or ridge-
and-channel arrangement constructed parallel to the
contours along the face of the slope at regular intervals
on long and steep slopes (in sloping areas with slopes
greater than 10 percent) (see Fig. 1). They are used for
reducing runoff velocity, increasing the distance of
overland runoff flow, and to hold moisture and
minimize sediment loading of surface runoff.
Vegetative cover of tree and native grasses in the
channels may be planted to stabilize the slopes and
reduce erosion.
4.2.3 Mulching
Mulching shall be used with seeding and planting in
steep slope areas (slopes greater than 33 percent) that
are prone to heavy erosion. Netting or anchoring shall
be used to hold it in place. Other surface runoff
control measures like contour terracing to break up
concentrated flows shall be installed prior to seeding
and mulching. Materials such as straw, grass, grass hay
and compost shall be placed on or incorporated into
the soil surface. In addition to stabilizing soils,
mulching will reduce the storm water runoff over an
area. Together with seeding or planting, mulching aids
plant growth by holding the seed, fertilizers and topsoil
in place. It retains moisture and insulates the soil against
extreme temperatures.
4.2.4 Geo-grids
A deformed or non-deformed netlike polymeric
material used with foundation, soil, rock, earth or any
other geo-technical engineering-related material as an
integral part of the human-made project structure or
system, called geo-grids may be used as control
measure. On filling with lightly compacted soil or fine
aggregate, a monolithic structure is created providing
an effective means of confinement for unconsolidated
materials within the cells and preventing their
movement even on steep slopes. If required the area
can then be seeded to maintain 'green' environment.
The junctions have a central opening through which
water can permeate ensuring that organic material
receives moisture for rapid growth.
5 SOIL AND WATER CONSERVATION
The soil conservation, sediment control and storm
water management practices as given in 5.1 to 5.3 shall
be followed after construction is completed.
5.1 Vegetative Measures
The vegetative measures shall include the following:
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 1 LANDSCAPE ...
150-200
mm
SECTION XX
P " "
JE
IE
OOKS
PLAN
Fig. 1 Typical Contour Trenches
5.1.1 Topsoil Laying
This includes the placement of topsoil or other suitable
plant material over disturbed lands to provide suitable
soil medium for vegetative growth. Topsoil laying shall
involve replacing fertile topsoils that were stripped and
stockpiled during earlier site development activities;
the laid soil shall be stabilized before the next monsoon
by planting grass, shrubs and trees.
The following guidelines shall apply to the placement
of topsoil:
a) The existing or established grade of sub-soil
should be maintained.
b) A pH of 6.0 to 7.5 and organic content of not
less than 1 .5 percent by mass is recommended
for topsoil. Where pH is less than 6.0, lime
shall be applied to adjust pH to 6.5 or higher
up to 7.5. Any soils having soluble salt content
greater than 500 parts per million shall not be
used.
c) Prior to spreading the topsoil, the sub-grade
shall be loosened to a depth of 50 mm to
permit bonding. Topsoil shall be spread
uniformly at a minimum compacted depth of
50 mm on grade of 1:3 or steeper slopes; a
minimum depth of 100 mm on shallower
slopes is essential. A depth of 300 mm is
preferred on relatively flatter land.
5.1.2 PlantingfVe gelation Cover
The most effective way to prevent soil erosion,
sedimentation and to stabilize disturbed and
undisturbed land is through the provision of vegetative
cover by effective planting practices. The foliage and
roots of plants provide dust control and a reduction in
erosion potential by increasing the infiltration, trapping
sediment, stabilizing soil, and dissipating the energy
of hard rain. Temporary seeding shall be used in areas
disturbed after rough grading to provide soil protection
until final cover is established. Permanent seeding/
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NATIONAL BUILDING CODE OF INDIA
planting is used in buffer areas, vegetated swales and
steep slopes. The vegetative cover also increases the
percolation of rain-water thereby increasing the ground
water recharge.
5.2 Storm Water Management and Filtration
Techniques
The surface water flow is increased in urban areas due
to predominance of hard surfaces. Storm water
management techniques assure conservation of water
thereby increasing the ground water recharge. Filters
facilitate draining pollutants out from surface water
runoff through straining before discharge into the
drainage way. Rain-water harvesting and sullage
recycle systems need to be implemented on all new
constructions over 1 000 m 2 in urban areas (see also
Part 9 'Plumbing Services, Section 1 Water Supply,
Drainage and Sanitation').
5.2.1 Rain Water Harvesting Structures in Urban
Environment
5.2.1.1 Water harvesting refers to the collection and
storage of rain-water and also harvesting surface and
ground water, prevention of loss through evaporation
and seepage, and other hydrological and engineering
interventions aimed at conserving water.
5.2.1.2 The advantages of using rain water harvesting
structures in urban areas are as follows:
a) Water harvesting recharges ground water and
is an ideal solution to water problems in areas
with inadequate water resources.
b) Increase in ground water aquifer level due to
methods enhancing infiltration.
c) Mitigation of the effect of drought.
d) Reduction of storm water runoff into the
public drainage system.
e) Reduction of flooding of the roads during
monsoons.
f) Removal of pollutants and soil from the storm
water runoff.
g) Reduction of soil erosion.
5.2.1.3 Methods of ground water recharge may be as
follows:
a) Recharge pits,
b) Recharge trenches,
c) Re-use of abandoned dug wells,
d) Re-use of abandoned hand pumps,
e) Recharge shafts,
f) Lateral shafts with bore wells, and
g) Spreading techniques like percolation ponds,
check dams or gabion structures.
5.2.2 Structures for Rain-Water Harvesting and Soil
and Water Conservation
These may be as given in 5.2.2.1 and 5.2.2.2.
5.2.2.1 Infiltration techniques
a) Infiltration trenches — An infiltration trench
is a rock filled trench that receives storm
water runoff. Storm water passes through a
combination of pre-treatment measures, a
grass swale and into the trench to be stored in
void spaces and then infiltrates into the soil
matrix.
b) Bio-filtration swale/grass swale — Bio-
filtration swales are vegetated channels with
a slope similar to that of standard storm drain
channels (less than 0.6 percent), but wider and
shallower to maximize flow residence time
and promote pollutant removal by filtration
through the use of properly selected
vegetation. It has to be designed to trap
particulate pollutants (suspended solids and
trace metals), promote infiltration and reduce
the flow velocity of the storm water runoff. It
shall be integrated with storm water system
(see Fig. 2).
c) Sand filter — Sand filters are devices that filter
storm water runoff through a sand layer into
an underground drain system which conveys
the water to a detention facility. They are
effective in removing total suspended solids.
The effectiveness of sand filtration is
improved if it is preceded by a grass swale
with infiltration trench.
5.2.2.2 Detention facilities
a) Wet ponds — Wet ponds are constructed
basins that have a permanent pool of water
throughout the year (or at least throughout the
wet season). Wet ponds retain the storm water
runoff in a permanent pool and facilitate
pollution removal through settling and
biological update.
b) Storm water wet lands — Storm water wet
lands are structures similar to wet ponds, that
incorporate wetland plants into the design.
They have to be designed for treating storm
water runoff, and typically have less bio-
diversity than natural wetland systems. A
distinction should be made between using
a constructed wet land for storm water
management and diverting storm water
into natural wetland. The latter is not
recommended because it would degrade the
resource.
c) Wet vaults and storage tanks — Wet vaults
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 1 LANDSCAPE,
11
-SIDE SLOPES 4 : 1 OR LESS
SWALE SLOPES
2 TO 4 PERCENT
PLACE ON ENGINEERED CHECK DAM
IF SWALE GRADE EXCEEDS 4 PERCENT
-150 mm TOP SOIL
Fig. 2 Grass Swale
and tanks are underground facilities used for
the storage of surface water, and typically
constructed from reinforced cement concrete
(vaults) or corrugated pipes (tanks). The water
that is captured in these vaults and tanks may
be used later for irrigation.
53 Conservation and Re-use of Water for Irrigation
The following measures shall be followed for design
of irrigation systems for landscape works:
a) Water conserving irrigation systems should
differentiate between systems for different
water use zones on the site. Supplementary
irrigation sources should be used by means
of appropriate water harvesting measures.
b) The irrigation system should be designed
considering the prevailing wind direction,
slope and proposed grade, type of soil, soil
percolation, and the type of vegetation to be
watered.
c) Spray irrigation to be designed to provide total
head to head cover to avoid dry spots and spray
on to paved areas and unplanted surfaces.
d) Spray irrigation is to be avoided in areas of
width less than 3.00 m.
e) Sullage recycle systems are ideal for large
housing complexes and residential colonies.
Sullage (or water from kitchens and
bathrooms) is treated and recycled for
gardening and toilet flushing reducing fresh
water requirement by 60 percent. Irrigation
system should be designed keeping sullage
recycle in view.
f) For requirements regarding, the volume of
water for different kinds of landscapes, see
Part 9 'Plumbing Services, Section 1 Water
Supply, Drainage and Sanitation' may be
referred.
6 EARTH SLOPES AND GRADING REQUIRE-
MENTS
6.1 Grading Design
Design for changes in elevation in the outdoor
environment is a primary component of landscape
development. Grading of proposed external
development areas should relate to the existing
topography of the site and it should direct surface water
runoff to the designed drainage and water harvesting
area. Grading design parameters are as follows:
a) The proposed grading design should respond
to the function and purpose of the activities
to be accommodated within the site.
b) New development and structures to be
integrated with existing landform within the
site and in its immediate surroundings.
c) Storm water to be directed away from buildings.
d) Terraces, levels and slopes in required areas
to be created and to emphasize control, or
negotiate circulation routes and views.
e) Steep slopes to be modified to minimize or
eliminate erosion.
f) Legally, grades cannot be changed beyond the
property line of the site.
g) The rate of storm water runoff leaving the site
after construction to not exceed the pre-
construction rate.
h) Grading design should optimize cut and fill.
6.2 Grading Plan
6.2.1 The submitted grading plan should include the
following:
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NATIONAL BUILDING CODE OF INDIA
a) All existing features of the site, including all
building with plinth level;
b) Structures such as walls, walks, steps, roads,
etc;
c) Utilities such as water lines, sewer and storm
water drainage, electrical lines, etc; and
d) Utility structures like manholes, junction
boxes, sewage treatment plant, septic tank,
soak pit, water tanks, water treatment plant,
transformers and all underground structures
indicated appropriately.
Proposed features shall be indicated in firm lines and
existing features in dash. *
6.2.2 The grading plan should represent:
a) General landform concept graphically
represented with appropriate symbols and
abbreviations (see 6.4).
b) Proposed contour lines should be integrated
with existing and proposed elevations within
the project site.
c) Location of swales and surface water flow,
surface and sub-surface soil drainage system
or water harvesting systems.
d) Location of drainage catchments, areas of
retention/detention or disposal/outfall point
as the case may be.
e) Spot grades on road, walks, and swales
including top level and relevant invert levels
of all utilities and utilities structures as
mentioned above; critical spot elevation to be
established (see 6.2.3).
f) Spot elevation of building floor finish level,
steps, walls, terraces and other such structures.
g) Changes in direction or rate of slope.
6.2.3 Spot Elevations
Spot elevations shall be used to supplement contours
in the following situations:
, c % x Vertical Rise x 100
a) Percentage (of slope) = — — : — ,
Horizontal distance
1 xlOO „
for example — = 2 percent
F 50 m
a)
b)
c)
d)
e)
f)
To indicate variations from the normal slope
or gradient between contour lines.
To indicate elevations of intersecting planes
and lines, like corners of buildings, walls,
steps and kerbs.
To indicate elevations at top and bottom of
vertical elements like walls, steps and kerbs.
To indicate floor and entrance elevations.
To indicate elevations of high and low points.
To indicate top elevations of utilities and
utilities structure.
b) Proportion (of slope) =
6.3 Slope Calculation
Slopes are expressed as follows:
Vertical Rise (1.0 m)
Horizontal distance
for example 1 m in 50 m or 1:50
c) Degree of slope, expressed as angle for
example 10°, 15°, etc.
6.4 Typical Grading Symbols and Abbreviations
Symbol Description
- -(100)- - Existing contour
— 100 — Proposed contour
(100.5) Existing spot elevation
100.5 (Bold) Proposed spot elevation
CB Catch basin
FFL Finished floor level
FGL Finished ground level
TW/B W Top of wall/Bottom of wall
TK/BK Top of kerb/Bottom of kerb
HP/LP High point/Low point
IL Invert level
7 PLANTING DESIGN CONSIDERATIONS
Plant materials are a very important component of
landscape design, and planting design is integral to the
landscape plan. Designing with plants requires
awareness and knowledge of a broad range of aspects
including (a) ecology, (b) botany, (c) horticulture,
(d) aesthetic value, (e) growth and survival, and (f) use
of plants to fulfil environmental design functions.
7.1 Plant Material
The major sets of factors that influence the choice of
plant material are related to the characteristics, both
botanical and physical of plant material and the context
in which the plant material is to be used. The inter-
relationship of these sets of factors is the basis for
developing a sound approach to the process of
designing with plants.
7.1.1 Physical and Botanical Characteristics of Plant
Material
The information on plant material should be available
in a systematic format to include definition,
significance and design implications of the following
aspects:
a) Nomenclature (botanical and trade-name);
b) Origin, family and natural habitat;
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 1 LANDSCAPE,
13
c) Growth characteristic and form as a function
of habit;
d) Physical characteristics, for example bark
texture, foliage, etc;
e) Propagation and maintenance; and
f) Use in landscape design.
7.1.2 Vegetation Types (Evergreen and Deciduous)
Some examples of the functional implications of using
evergreen and deciduous plant material for specific
situations are:
a) Evergreen trees for:
1) places requiring shade throughout the
year,
2) strong visual screening,
3) part of windbreak or shelter planting,
and
4) areas where leaf litter is to be discouraged.
b) Deciduous trees for:
1) greater visual variety,
2) partial visual barrier,
3) areas where under-planting is to be
encouraged (for example grass),
4) emphasis on branching and flowering
pattern, and
5) areas where shade is not required
throughout the year.
7.1.3 Growth Rate and Age of the Vegetation
Growth rate is directly related to the life-span of a tree
and slower growing trees have a life-span extending
to hundreds of years. The fast growing trees to
the exclusion of slower growing varieties is not
recommended. Landscapes are developed to sustain
future generations; slow growing long lived native trees
shall be emphatically included in all major planting
schemes, specially those related to institutional
campuses and large urban development. However, fast
growing species do have a limited role, and are
appropriate in situations where:
a) Quick effects are required, for example in
windbreaks and shelterbelts.
b) Immediate results with regards to stabilization
of soil, etc are necessary, as for example, in
soil conservation schemes.
c) As 'nurse plants' to protect slower growing
sensitive species when necessary.
The slower growing species would generally be
appropriate in situations where sustained environmental
benefits are required such as roadside planting,
campuses, townships, industrial areas, and other public
landscapes.
7.1.4 Growth Habits of Various Kinds of Vegetation
and their Form
The overall physical form of a plant is usually the result
of the foliage density and branching pattern. It may
also be expressed as the proportionate relations
between height and canopy spread. The latter is direct
expression of growth habit.
A number of classifications of tree by their overall form
exist, but it is almost impossible to have a variety
according to regional conditions. The following
classification into basic types may be useful:
a) Trees of fastigiated or columnar habit —
Examples of trees of this type are:
Casurina equisitifolia (Beet-wood)
Grevillea robusta (Silver oak)
Polyathia longifolia (Ashok)
Populus species (Poplar).
Though the branching pattern of each is
different, the overall shape is similar.
b) Tall trees with broad canopy — Examples of
trees of this type are:
Dalbergia sissoo (Sheesham)
Tamarindus indica (Imli)
Terminalia arjuna (Arjun).
The canopy shape does not fit into any
specific geometrical category.
c) Trees of spreading habit — Examples of trees
of this type are:
Delonix regia (Gulmohar)
Lager stromiaflosreginae (Pride of India)
Pithecolobium soman (Rain Tree).
Though these trees vary greatly in size, their
basic form is similar.
d) Trees of weeping habit — Examples of trees
of this type are:
Callistemon lanceolatus (Bottle brush)
Salix babylonica (Weeping willow).
The above classification is helpful in choosing various
combinations of the above types to achieve desired
function and visual objectives.
7.1.5 Foliage Characteristics of Plant Material
Visual effects imparted by vegetation, for example, the
perceived visual textures of plant forms depend on:
a) Leaf size and shape — Examples of plants
with large leaves and bold foliage texture are:
Alstonia scholaris (Chattin Saptporni)
Delonix regia (Gulmohar)
Jacaranda miosaefolia (Nili Gulmohar)
Plumeria acutifolia (Temple Tree)
14
NATIONAL BUILDING CODE OF INDIA
Pterospermum acerifolium (Kanak
Champa).
Leaf shape can also determine the appearance
of the foliage of the plant, as for example:
Acacia auriculaeformis (Australian
Black wood) — Long narrow leaves
Callistemon lanceolatus (Bottle Brush)
— Narrow leaves giving a feathery
appearance
Polyalthia longifolia (Ashok) — Long
narrow leaves
Salix babylonica (Weeping willow) —
Narrow leaves giving a feathery
appearance.
b) Leaf texture — The textural appearance of a
plant is the result of the play of light and shade
on the foliage. Plants with larger leaves
generally appear bolder in texture than smaller
leaves plants as the areas of light and
shade are larger and therefore more clearly
differentiated.
c) Leaf and foliage colour — Most trees in India
have foliage in varying shades of green with
variations in colour at the time of leaf fall and
at the period when the tree is newly in leaf,
when the leaves are fresh and much lighter in
colour. Examples are:
Lagerstroemia speciosa (Jarul) —
Leaves acquire reddish tinge before
falling
Polyalthia longifolia (Ashok), Delonix
regia (Gulmohar), Erythrina indica
(India coral tree), etc — Leaves turn
yellow before falling
Ficus, intectoria (Pilkhan) Mangifera
indica (Mango) etc — Young leaves have
reddish tinge.
d) Foliage density and distribution — An
important consideration is the way in which
particular kinds of vegetation are perceived.
Tree masses are usually seen from greater
distance than shrub areas; foliage texture of
different distinctive kinds of trees growing
together has to be markedly distinctive
for individual species to be recognizably
apparent. In shrub areas subtle differences in
foliage texture may suffice for creating the
required visual effect.
7.1.6 Flowering Characteristics of Plant Material
7.1.6.1 Important considerations while classifying
plant material according to flowering characteristics
are as follows:
a) Season,
b) Density and distribution of flowers on the
plant,
c) Botanical characteristics of flowers (for
example single/cluster, etc),
d) Colour, and
e) Presence or absence of foliage during
flowering period.
7.1.6.2 For the purpose of understanding the visual
effect of flowers, tree species may be divided into two
types:
a) Trees on which flowers appear in profusion
and therefore have a very strong visual
impact, for example Delonix regia, Cassia
fistula, Lagerstroemia flosreginae.
b) Those on which flowers are less profuse, or
perhaps last for a shorter period and visual
impact is more subtle, for example Thespesia
spp., Bauhinia spp., etc.
An additional consideration when choosing shrubs for
their flowering quality is the visual appearance of the
flowers themselves, as shrubs are usually seen from
quite close. Distinctive flowers are those of
a) Beleperone guttata (Shrimp plant),
b) Hibiscus rosa-sinensis (Clinex hibiscus),
c) Jasminum sambac (Chameli),
d) Tabernaemontana coronaria (Cape jasmine),
and
e) Thevetia peruviana (Yellow oleander).
7.1.6.3 The olfactory characteristics, that is, odour, of
flowers may be an added benefit of flowering plants.
Rowers with distinctive scent include those of Har-
singar (Nyctanthes arbor-tristis\ Chameli {Jasminum
pubescens), Raat Ki Rani (Cestrum nocturnum), etc.
7.1.6.4 Flowering characteristics of plant material may
be classified as per the following format:
Botanical
name
Characteristics
of flower
Seasonal
duration
Visual
impact
1A.1 Growth Requirement of Plant Material
Information about growth requirements of plant
material applicable in landscape design pertains to the
ability of particular plants to survive in specific
environmental situations. These environmental
conditions may arise from a number of aspects as given
in 7.1.7.1 to 7.1.7.4. Capacity of plants to grow in
cultivated situations is related to the environmental
conditions obtaining in their natural habitat.
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 1 LANDSCAPE...
15
7.1.7.1 Soil conditions
Physical as well as chemical properties of the available
soil are important. These may or may not be amenable
to change, they would therefore affect the choice of
plant material considerably. Physical properties include
consideration of light (for example sandy) and heavy
(for example clayey) soils, and their structure.
Chemical properties pertain to the presence or absence
of nutrients and salts; soil, alkalinity or acidity. A
preliminary soil analysis is essential for implementing
effective planting schemes.
7.1.7.2 Availability and quality of water
The water requirement may be derived by data of
humidity and rainfall of plants natural habitat. The
water table of the area where the plantation is to be
done has a crucial bearing on the design with plants as
well as a financial implication for reduced maintenance
if planted appropriately.
7.1.7.3 Availability of sunlight
The growth rate of plants are directly related to sunlight
availability; such as plants that require (a) full sunlight,
(b) partial sunlight, (c) predominantly shade, and
(d) complete shade.
7.1.7.4 Quality of air
Growth may be affected by chemical pollutants such
as sulphur dioxide or physical pollution such as dust.
Certain plants have the ability to withstand pollution,
such plants are imperative for industrial areas, roads,
highways, etc.
7.1.8 Maintenance
The success of a designed landscape depends upon the
growth of vegetation over an extended period of time;
therefore maintenance of landscape is also a design
component. Maintenance needs and practices in any
given situation arises out of the inter-relationship
between the growth requirements of plant material
chosen and the environmental conditions existing on
site.
The likely degree of maintenance should be assessed
based on the following:
a) Scale of the design project,
b) Financial and manpower resource,
c) Availability of manures,
d) Future intensity of site, and
e) Environmental conditions.
In small scale projects such as gardens and small parks,
the natural environmental conditions can be changed
and maintained by management practices such as
irrigation and application of fertilisers. The choice of
plant species is therefore not very strictly limited by
the existing environmental conditions. On larger scale
schemes, such as very large parks, campuses and
townships, this kind of intensive maintenance may not
be possible. The process of choosing plants shall
therefore respond to the existing environmental
conditions and also in such cases the choice of plant
material is restricted by these conditions and suitable
species become limited. The type of treatment adopted,
as given below, may also serves as a guide to the degree
of maintenance required:
a) Low The lowest degree of
Maintenance maintenance is usually possible
in areas treated with native
species of trees only.
A slightly higher degree is
necessary where native shrubs
are also used, as these may
require pruning.
b) Medium Areas treated with a mixture of
native and exotic trees.
Exotic shrubs and trees.
c) High Exotic shrubs and ground
covers.
Lawns and maintained grass
areas.
Annual flowers and special
schemes.
7.2 Functional Aspects of Design with Plants
Plant materials in landscape design may be used to:
a) improve existing environmental conditions
with respect to soil, drainage, microclimate,
air pollution;
b) create a designed physical environment
through the organization of open space;
and
c) interpret and express the contemporary
understanding of the man-nature relationship,
that is, design with plants on an ecological
rather than horticultural basis.
7.2.1 Choosing of Plant Material
Two sets of factors influence the choice of plant
material in landscape design. One relates to information
about plant material itself, that determines the
suitability of plant material from the point of view of
growth requirements of plant material, and physical
characteristics of the plant material. The second relates
to the situation for which a planting proposal has to be
made that pertains to the context in which the plant
materials have to be used. Considerations of scale (that
is, regional, local or very small scale situations), the
16
NATIONAL BUILDING CODE OF INDIA
existing environmental conditions, and functions which
the plant material has to fulfill are important. Also the
level of maintenance which is likely to be kept up, has
to be considered which is specially important on very
large sites. The biological history and ecological need
of exotic plant should be studied prior to introduction
in the landscape schemes to avoid the hazard of the
species that may become invasive.
The factors determining choice of plant materials may
be thus summarized as follows:
a) Environmental conditions existing on site —
These include climatic, soil characteristics,
water table, etc.
b) Functions which plant material has to fulfill
in specific situations on a given site — These
may be either environmental functions
(pertaining to improvement of soil conditions,
modification or microclimate, etc) or design
functions relating to creating spaces
enclosure, framing views, providing visual
relief, etc.
c) Physical characteristics and growth
requirements of plant material — The former
include foliage density, foliage texture, leaf
size and shape, flower colour, rooting
characteristics, etc. The latter include
moisture requirements, whether the plant
grows in sunny or shaded conditions, etc.
7.2.2 Methodology of Design with Plants
The process for designing with plants on a given
condition may be as per the format given below:
site
Zone
Characteristics
Functions
Form
Species
chosen
Remarks
Plant material used in landscape design may be broadly
classified as:
Tree
Shrub
Large
Medium
Small
Tall
Low
Ground cover Very low shrubs less than a
300 mm high
7.2.3 Functions of Plant Material
7.2.3 .1 Trees
Trees perform the following functions:
a) Protecting soil,
b) Modifying microclimate,
c)
Shade,
d)
Habitat,
e)
Enclosure,
f)
Direction and framing views,
g)
Screening,
h)
Visual relief, and
J)
Ornamental.
NOTE — For functions of plants/shrubs to reduce noise,
3.6 of Part 8 'Building Services, Section 4 Acoustics,
Sound Insulation and Noise Control' may be referred.
7.2.3.2 Shrubs
The functions are similar to those of trees. Shrubs may
be used together with trees to reinforce the functions,
for example, noise barrier, shelter belts, enclosures,
etc.
Other forms in which shrubs may be used are:
a) Hedges — These require regular maintenance
b) Shrubbery — Here plants are allowed to retain
their natural shape; they therefore require little
maintenance.
Shrubs provide barriers, which may either be visual or
physical (hedges). Barriers may be required in a range
of situations, for example they may be only for defining
space, or they may be required for security and have
to be, therefore, necessarily impenetrable.
7.2.3.3 Ground cover
Ground cover plants are those which naturally grow
to a very low height. Some of the uses for which they
may be used are:
a) Stabilizing soil on steep slopes such as
embankments.
b) As a low maintenance substitute for grass
(where the surface is not to be used).
c) For providing variety in surface treatment.
d) Contrast with paving materials, for example
to soften rigid lines of paving.
e) As a subtle means of demarcating space, as
for example, in places where tall plants would
be visually intrusive.
f) In combination with other plants to provide
contrast or harmony in form.
7.2.3.4 Climbers
Certain climbers because of their spreading habits may
also be used as ground cover (for example Asparagus
spp.) Climbers are useful for shading exposed walls
from direct sunlight. They may also be used for
stabilizing soil on embankments (for example, Ficus
stipulata, Ipomea biloba). On sites where a high degree
of security makes fencing necessary, climbers and
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 1 LANDSCAPE.
17
spreading plants like Bougainvillea species, may be
trained on boundary wall.
7.3 Planting for Shelter and Soil Conservation
The use of vegetation for controlling wind is widely
recognized as an effective way of conserving soil and
reducing erosion by wind. Vegetation may therefore
be used for modifying the microclimate, by obstructing,
guiding, deflecting or filtering wind current.
Vegetation areas designed to fulfill these general
functions are usually classified as windbreakers and
shelterbelts. Windbreaker is grown protective planting
around gardens and orchards. Windbreakers generally
consist of single or double row of trees. Shelterbelt
provides an extensive barrier of trees with several rows
of trees. Plant species are chosen with particular regard
to their physical and growth characteristics, and their
effectiveness in achieving the desired results. Both
windbreakers and shelterbelts have considerable visual
impact in the landscape in which they are situated, they
therefore need to be designed so that they make a
positive visual and aesthetic contribution to their
environment.
7.3.1 Function
Windbreakers and shelterbelts fulfill essential micro-
climatic functions in rural and urban environments.
Benefits accruing from plantation of shelter planting
may be as follows:
a) Reduction in wind velocity resulting in the
arrest of movements of sand and soil
particles.
b) Prevention of soil erosion.
c) Modification of micro-climate; moderation of
change in air temperature.
d) Protection of crops from being blown by high
winds.
e) Protection of livestock.
f) Reduction in evaporation of soil moisture.
Increase in soil moisture content varies from
3 percent to 7.8 percent. Water loss due to
evaporation is lessened.
g) Increase in soil moisture due to greater
dewfall in sheltered areas has been found to
be 200 percent higher than on exposed
ground; heaviest dew fall is over a distance
of 2 to 3 times the height of the shelterbelt.
h) Beneficial effect on growth of plants that are
affected by high winds,
j) Extensive shelterbelts may also be used to
augment the supply of fuel in rural areas,
k) The zone of influence of shelterbelt on crop
yield extends to a distance of 20 times the
height of the belt, with the maximum effect
being observed 10 times the height of the tree
belt, on the leeward side.
7.3.2 Wind Erosion
Some of the basic functions of windbreaks and
shelterbelts in arid and semi-arid areas are to conserve
soil and reduce erosion by wind (see 7.3). The latter is
a natural phenomenon in and lands having very little
rainfall (125 mm-250mm) and in areas adjoining a
river, lake or sea. Wind erosion is a serious problem in
areas where the ground is virtually bare and devoid of
vegetation.
Factors which influence the degree and kind of wind
erosion are as follows:
a) Features of wind — Speed, direction,
temperature, humility, burden carried, etc.
b) Character of surface — Rough or smooth
plant cover, obstruction, temperature, etc.
c) Topography — Flat, undulating broken,
etc.
d) Character of soil — Texture, organic matter,
moisture content, etc.
7.3.2.1 Techniques for control of wind erosion
The principal method of reducing surface velocity
of wind, upon which depends the abrasive and
transportation capacity of wind, is by vegetation
measures. Vegetation methods are found to be most
effective in the form of windbreaks and shelterbelts.
In aerodynamic terms, these provide protection as
follows:
a) Sheltered zone on the leeward side extends
to approximately 15-30 times the height of
the belt.
b) A dense belt provides greater shelter
immediately toleeward side but the sheltered
area is not as extensive as when a more
permeable zone of vegetation is provided.
c) Porosity is important in the effectiveness of
shelterbelt and proper selection of tree species
is necessary. Porosity near ground level is
desirable.
d) Effectiveness of shelter planting depends
more on height and permeability than on
width. The width influences the general
microclimate but above a certain minimum
width, it does not effect greater reduction in
wind velocity.
Protection obtained varies in relation to height (H) of
shelterbelts, as given below:
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NATIONAL BUILDING CODE OF INDIA
Distance
Wind Reduced by
(in percent)
H
90
2H
75
5H
50
10//
20
This indicates that it is better to have several
windbreaks 5// to 6// apart rather than large forest
stands with wide open spaces in between.
7.3.3 Profiles
A belt which rises and falls abruptly on windward and
leeward sides is said to be more effective. Smaller trees
and shrubs should occupy the inter-spaces between the
tall tree.
NOTE — Some authorities maintain that triangular section of
shelterbelt planting is more effective.
The depth of the shelterbelt should be approximately
ten times its height. This is, however, only a thumb
rule. Much lesser widths of 20 m to 30 m have also
been found to be useful in particular situations; 15 m
should be considered as minimum width.
Apart from factors such as climate, soil, fast rate of
growth, one of the more significant considerations in
choosing species for shelter planting is the possibility
of a particular species serving the dual role of wood-
production (for fuel, fodder) as well as shelter.
7.3.3.1 Spacing of plants in windbreaks and shelterbelts
Windbreaks usually consist of a single or double row
of trees planted at 0.7 m to 1 .5 m according to species.
Normally, one year old trees are used. As the roots of
tree extend for some distance beyond the rows in which
they are planted, the same should be taken into account
while planting windbreakers. The most common layout
where shelter planting is part of an extensive planned
programme, is that of tree belts arranged in a
chessboard pattern, each field being-protected from
every side. This pattern gives full protection to all the
fields, provided that the right distance between the
fields has been chosen. Efficient protection is achieved
if belts are separated by a distance of not more than 20
times the height of the trees. A considerable mixture
of species is recommended so as to compensate for
different rates of growth and also to achieve variety in
the form of crowns.
7.3.3.2 Within shelterbelts, close spacing of tree is the
general practice. The recommended spacing for shrubs
is 1 m and for tree such as Casuarina and Grevellia
robusta (Silver Oak) 2.5 m. Spacing between rows
should be 2.3 m to 3 m to enable mechanized
cultivation. Five rows of tree and shrubs are considered
necessary for protection.
7.3.4 Management
Shelterbelts should be regarded as living groups of
trees to be managed in perpetuity and the following
shall be taken into consideration for management
thereof:
a) Thinnings are limited to a strict minimum.
b) Cutting is done individually by single tree
selection method.
c) Continuous cultivation may be required in
areas with scanty rainfall.
d) If individual trees do not survive, they should
be replaced immediately to avoid gaps in the
vegetation belt. The shelterbelt should be
protected from cattle, either by fencing or
other means, specially in the early stages.
The location of shelterbelt may be related to local
features such as public and private road networks,
buildings, irrigation and water conservation works and
methods soil management practice (contour bunding,
contour cultivation etc). Careful choice of site will
provide maximum protection to adjacent land and give
shelter and shade.
The application of the concept of shelterbelts to
landscape planning and design may be effective in
the creation of landscape structure of very large
developments at the regional scale, or townships or
campuses. Shelterbelts can also be established in
association with, or instead of road side planting. This
itself creates a distinctive landscape pattern. The
advantage of using native species in shelter planting
are:
a) New development is merged into the existing
landscape. The original character of the
landscape is therefore not obtruded upon.
b) The shelterbelt is a component of land
management (previous waste or barren land
is conserved).
c) Additional habitat for wildlife are brought into
existence.
7.3.5 Species-suitable for wind breaks are:
a) For Dry and Arid Regions
Acacia auriculiformis (Australian Blackwood)
Ailanthus excelsa (Maharukh)
Albilzia lebbeck (Siris)
Azadiracta indica (Neem)
Casuarina equisetifolia (Beef-wood)
Dalbergia sissoo (Sisham)
Eugenia jambolana (Jamun)
Grevillea robusta (Silver oak)
Peltophorumferrugineum (Cooper pod)
Tamarindus indica (Imli)
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Pongamia glabra (Indian beech)
Tamarix articulata (Tamarisk)
b) For Coastal Area
Anacardium occidentale (Cashu)
Ailanthus malabarica (Alston)
Cassuarina equisetifolia (Beef-wood)
Pongamia glabra (Indian beech)
Sesbania aculeate (Sesban)
Thevetia peruvian (Yellow oleander)
Thespesia populnea (Indian Tulip)
Vitex negundo (Sephali)
7.4 Air Pollution Control by Plants
Air pollution may be caused by areas or point sources
such as cities, industrial areas, factories or by linear
sources such as highways. Vegetation buffers can
minimize the build-up of pollution levels in urban
areas, by acting as pollution sinks.
Studies have establised that air pollution, smoke and
sulphur dioxide leads to an exacerbation of chronic
respiratory diseases and they are linked to lung cancer,
pnemonia, tuberculosis, chest disease in children,
stomach cancer and cardiovascular diseases. Lead from
vehicle exhausts may have an adverse effect on mental
health of children, asbestos from disintegrating clutch
and brake linings has been considered as a causal factor
in lung cancer.
7.4.1 Effect of Plants
Plant leaves function as efficient gas exchange systems.
Their internal structure allows rapid diffusion of water-
soluble gases. These characteristics allow the plant to
respire and photosynthesise, and they can also remove
pollutant from the air. Some of the beneficial results
of plantations may be:
a) They are good absorbers of sulphur dioxide.
b) Parks with trees have an S0 2 level lower than
city streets.
c) Roadside hedges can reduce traffic generated
air borne lead, on leeward side.
d) Heavy roadside planting in the form of
shelterbelts can result in a reduction in
airborne lead.
e) Complete dust interception can be achieved
by a 30 m belt of trees. Even a single row of
trees may bring about 25 percent reduction
in airborne particulate.
7.4.2 Choosing Plants
The three main criteria for selection of plants may be:
a) Tree, shrubs should have a dense foliage with
a large surface area, because leaves absorb
pollutants.
b) Evergreen trees are found to be more
effective.
c) The species chosen must be resistant to
pollutants, particularly in the early stages of
their growth.
The following species may be examined for their likely
potential for pollution control:
Acacia arabica (Babul)
Citrus species
Dyospyros species
Ficus bengalensis (Banyan)
Ficus religiosa (Peepal)
Lilium spp. (Lily)
Polyalthia lotigifolia (Ashok)
Tamarindus indica (Imli)
Thuja occidentalis (Cedar)
Prosopis Juliflora (Mesquite)
Zizypus jujuba (Jujuba), etc.
Filtering of pollutants is most effective when plants
are close to the source of pollution. The design of
shelterbelts against pollution is similar to those for
protection from wind. They should be permeable to
encourage air turbulence and mixing within the belt.
There should be no large gaps. The profile should be
rough and irregular and should present a tall vertical
leading edge to the wing. Spaces should be left within
the shelterbelt to allow gravity settlement of particles.
7.4.3 Applications
Air pollution shelterbelts may be used to protect
sensitive land uses from air pollution. For instance
school playgrounds, children play area and residential
estates close to major roads may be so protected.
Shelterbelt protection may also be provided for
hospitals, institutions, etc, where the vegetation may
also be a visual screen and a partial noise barrier.
Vegetation may also be used where the existing means
of pollution control have proved inadequate.
8 SPECIFICATIONS FOR PLANTING WORKS
The requirements relating to plant materials and other
materials; execution of work of tree planting, shrub
planting and grassing; maintenance; etc shall be as
given in 8.1 to 8.6. The contractor shall furnish all
materials, labour and related items necessary to
complete the work indicated on drawing and specified
herein and shall carry out maintenance of the premises
for 12 months after completion of the work or as
specified by the landscape architect.
8.1 Materials
8.1.1 Plant Materials
Plant materials shall be well formed and shaped true
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NATIONAL BUILDING CODE OF INDIA
to type, and free from disease, insects and defects such
as knots, windburn, injuries, abrasion or disfigurement.
All plant materials shall be healthy, sound, vigorous,
free from disease, insect pests, or their eggs, and shall
have healthy, well-developed root systems. All plants
shall be hardy under climatic conditions similar to those
in the locality of the project. Plants supplied shall
conform to the names listed on both the plan and the
plant list. No plant material will be accepted if branches
are damaged or broken. All material shall be protected
from sun and adverse weather until planted. Nursery
stock shall be inspected and approved by the landscape
architect and the horticulturist/botanist shall do the
botanical authenticity of the selected species.
All plants shall conform to the requirements specified
in the plant list, except those plants larger than specified
may be used if approved, but use of such plants shall
not increase the contract price. If the use of the larger
plant is approved, the spread of roots or ball of earth
shall be increased in proportion to the size of the plant.
Plants shall be delivered with legible identification
labels.
The minimum acceptable size of all trees after
prunning, with branches in normal positions, will
conform to the measurement specified in the bill
of quantities unless stated otherwise. Caliper
measurement will be taken at a point on the trunk 1 .0 m
above natural ground. All trees supplied shall have
terminal shoots. All specimen trees shall have a
minimum crown spread of not less than half the size
of the overall height.
8.1.2 Topsoil (Good Earth) with pH Range between
6.5 to 7.5
Topsoil or good earth shall be a friable loam; typical
of cultivated top soils of the locality contains at least 2
percent of decayed organic matter (humus). It shall be
taken from a well-drained arable site. It shall be free
of sub-soil, stones, earth clods, sticks, roots or other
objectionable extraneous matter or debris. It shall
contain no toxic material. No topsoil shall be delivered
in a muddy condition.
8.1.3 Fertilizer
Dry farm yard manure shall be used. Measurement shall
be in stacks, with 8 percent reduction for payment. It
shall be free from extraneous matter, harmful bacteria
insects or chemicals.
8.1.4 Root System
The root system shall be conducive to successful
transplantation. Where necessary, the root-ball shall
be preserved by support with hessian or other suitable
material. On soils where retention of a good ball is
not possible, the roots should be suitably protected
in some other way which should not cause any
damage to roots.
8.1.5 Condition
Trees and shrubs shall be substantially free from pests
and diseases, and shall be materially undamaged. Torn
or lacerated roots shall be pruned before dispatch. No
roots shall be subjected to adverse conditions, such as
prolonged exposure to adverse conditions, such as
prolonged exposure to drying winds or subjection to
waterlogging, between lifting and delivery.
8.1.6 Marking
Each specimen of tree and shrub, or each bundle, shall
be legibly labelled with the following:
a) Its name.
b) Name of the supplier, unless otherwise
agreed.
c) Date of dispatch from the nursery.
8.2 Execution
8.2.1 Fine Grading
Grades will be smooth and even on a uniform plane
without abrupt changes or pockets and slope away from
the buildings. The nominated landscape contractor will
verify the surface drainage of planting areas and notify
the landscape architect of any discrepancies,
obstructions or other conditions considered detrimental
to proper execution of the work and plant growth.
8.2.2 Landscape work will be tied to the existing
condition such as existing trees palms, landscape
features, utility lines, pavement kerbs, etc. Finished
grade will bear proper relationship to such control. The
nominated landscape contractor shall adjust all works
as necessary to meet the conditions and fulfill the
intention of the drawings.
After initial settlement the finish grade will be:
a) Turf: 20 mm lower than adjacent walks/
kerbs.
b) Shrubs and Ground covers : 40 mm lower
than adjacent walks/kerbs.
Prior to planting operation, the contractor will ensure
all planting areas free of weeds, debris, rocks over
25 mm in diameter and clumps of earth that do not
break up.
8.3 Tree Planting
8.3.1 Trees should be supplied with adequate
protection as approved. After delivery, if planting is
not to be carried out immediately, balled plants should
be placed cheek to cheek and the ball covered with
sand to prevent drying out. Bare rooted plants can be
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21
heeled in by placing the roots in a prepared trench and
covering them with earth which should be watered in
to avoid air pockets round the roots.
8.3.2 Digging of Pits
Tree pits shall be dug a minimum of three weeks prior
to backfilling. The pits shall be 1 200 mm in diameter
and 1 200 mm deep. While digging the pits, the topsoil
up to a depth of 300 mm may be kept aside, if found
good (depending upon site conditions), and mixed with
the rest of the soil. If the soil is bad below, it shall be
replaced with the soil mixture as specified further
herein. If the soil is normal it shall be mixed with
manure; river sand shall be added to the soil if it is
heavy.
8.3.3 Flooding of Pits to Reduce Air Pockets
The soil backfilled, watered through and gently pressed
down, a day previous to planting, to make sure that it
may not further settle down after planting. The soil
shall be pressed down firmly by treading it down,
leaving a shallow depression all round for watering.
8.3.4 Planting
No tree pits shall be dug until final tree positions have
been pegged out for approval. Care shall be taken that
the plant sapling when planted is not buried deeper
than in the nursery, or in the pot. Planting should not
be carried out in waterlogged soil.
Trees should be planted up to the original soil depth;
the soil marks on the stem is an indication of this and
it should be maintained on the finished level, allowing
for setting of the soil after planting. All plastic and
other imperishable containers should be removed
before planting. Any broken or damaged roots should
be cut back to sound growth.
The bottom of the planting pit should be covered with
50 mm to 75 mm of soil. Bare roots should be spread
evenly in the planting pit; and small mound in the centre
of the pits on which the roots are placed will aid an
even spread. Soil should be placed around the roots,
gently shaking the trees to allow soil particles to shift
into the root system to ensure close contact with all
roots and to prevent air pockets. Back fill soil should
be firm as filling proceeds, layer by layer, care being
taken to avoid damaging the roots.
8.3.5 Staking
Newly planted trees shall be held firmly although not
rigidly by staking to prevent a pocket forming around
the stem and newly formed fibrous roots being broken
by mechanical pulling as the tree rocks.
The main methods of staking shall be:
a) A single vertical stake, 900 mm longer than
the clear stem of the tree, driven 600 mm to
900 mm into the soil.
b) Two stakes as above driven firmly on either
side of the tree with cross-bar to which the
stem is attached (suitable for small bare-
rooted or balled material).
c) A single stake driven in at an angle 45° and
leaning towards the prevailing wind, the stem
just below the lowest branch being attached
to the stake (suitable for small bare-rooted or
balled material).
The end of stake should be pointed and the lower 1 m
to 1.2 m should be coated with non-injurious wood
preservative allowing at least 150 mm above ground
level.
8.3.6 Tying
Each tree should be firmly secured to the stake so as to
prevent excessive movement. Abrasion shall be
avoided by using a buffer, rubber or hessian, between
the tree and stake. The tree should be secured at a point
just below its lowest branch, and also just above ground
level; normally two ties should be used for tree. These
should be adjusted or replaced to allow for growth.
8.3.7 Watering
The contractor should allow for the adequate watering
in all newly planted trees and shrubs immediately after
planting and shall, during the following growing
season, keep the plant material well watered.
8.4 Shrub Planting in Planters and Beds
8.4.1 All areas to be planted with shrubs shall be
excavated, trenched to a depth of 750 mm, refilling
the excavated earth after breaking clods and mixing
with manure in the ratio 8: 1 (8 parts of stacked volume
of earth after reduction by 20 percent; 1 part of stacked
volume of manure after reduction by 8 percent).
Tall shrubs may need staking: which shall be provided
if approved by the landscape architect depending upon
the conditions of individual plant specimen.
For planting shrubs and ground cover shrubs in
planters, good earth shall be mixed with manure in
proportion as above and filled in planters.
Positions of shrubs to be planted should be marked
out in accordance with the planting plan. When shrubs
are set out, precautions should be taken to prevent root
drying. Planting holes 400 mm in diameter and
400 mm deep should be excavated for longer shrubs.
Polythene and other non-perishable containers should
be removed and any badly damaged roots carefully
pruned. The shrubs should then be set in holes so that
the soil level, after settlement, will be at the original
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NATIONAL BUILDING CODE OF INDIA
soil mark on the stem of the shrub. The hole should be
back-filled to half its depth and firmed by treading.
The remainder of the soil may then be returned and
again firmed by treading.
8.5 Grassing
8.5.1 Preparation
During the period prior to planting the ground shall be
maintained free from weeds. Grading and final
levelling of the lawn shall be completed at least three
weeks prior to the actual sowing. Regular watering
shall be continued until sowing by dividing the
lawn area into portions of approximately 5 m 2 by
constructing small bunds to retain water. These bunds
shall be levelled just prior to sowing of grass plants.
At the time of actual planting of grass, it shall be
ensured that the soil has completely settled.
8.5.2 Soil
The soil itself shall be ensured to the satisfaction of
the landscape architect to be a good fibrous loam, rich
in humus.
8.5.3 Sowing the Grass Roots.
Grass roots shall be obtained from a grass patch, seen
and approved beforehand. The grass roots stock
received at site shall be manually cleared of all weeds
and water sprayed over the same after keeping the stock
in a place protected from sun and dry winds. Grass
stock received at site may be stored for a maximum of
three days. In case grassing for some areas is scheduled
for a later date fresh stock of grass roots shall be ordered
and obtained. Small roots shall be dibbled about 75 mm
apart into the prepared grounds. Grass areas will only
be accepted as reaching practical completion when
germination has proved satisfactory and all weeds have
been removed.
8.5.4 Maintenance
As soon as the grass is approximately 30 mm high it
shall be rolled with a light wooden roller in fine, dry
weather — and when it has grown to 50 mm to 80 mm
above ground, weeds shall be removed and regular
cutting with the scythe and rolling shall be begun. A
top-dressing of farm yard manure, bone meal at the
rate of 50 g/m 2 and NPK at the rate of 10 g/m 2 shall be
applied when the grass is sufficiently secure in the
ground to bear the mowing machine, the blades shall
be raised 25 mm above the normal level for the first
two or three cuttings. That is to say, the grass should
be cut so that it is from 40 mm to 50 mm in length,
instead of the 30 mm necessary for mature grass.
In the absence of rain, in the monsoon the lawn shall
be watered with sprinklers every, three days soaking
the soil to a depth of at least 200 mm. Damage, failure
or dying back of grass due to neglect of watering
specially for seeding out of normal season shall be the
responsibility of the contractor.
Any shrinkage below the specified levels during the
contract or defects liability period shall be rectified at
the contractor's expense. The contractor shall exercise
care in the use of rotary cultivator and mowing
machines to reduce to a minimum the hazards of flying
stones and brickbats. All rotary mowing machines are
to be fitted with safety guards.
8.5.5 Rolling
Lawn mower with roller shall be used periodically,
taking care that the lawn is not too wet and sodden.
8.5.6 Edgings
These shall be kept neat and shall be cut regularly with
the edging shears.
8.5.7 Watering
Water shall be applied at least once in three days
during dry weather. Water whenever done should be
thorough and should wet the soil at least up to a depth
of 200 mm.
8.5.8 Weeding
Prior to regular mowing the contractor shall carefully
remove rank and unsightly weeds.
8.6 Maintenance
8.6.1 The landscape contractor shall maintain all
planted areas within the landscape contract boundaries
for one year until the area is handed over in whole or
in phases. Maintenance shall include replacement of
dead plants, watering, weeding, cultivating, control of
insects, fungus and other diseases by means of spraying
with an approved insecticide or fungicide, pruning, and
other horticulture operations necessary for the proper
growth of the plants and for keeping the landscape
contract area neat in appearance.
8.6.2 Pruning and Repairs
Upon completion of planting work under the contract
all trees should be pruned and all injuries repaired
where necessary. The amount of pruning shall be
limited to the minimum necessary to remove dead or
injured twigs and branches and to compensate for the
loss of roots and result of transplanting operations.
Pruning and removal of any part of plant materials
should be done with clean sharp tools. Tools used to
carry out the prunning work shall be appropriate for
the task. The surface of tools and equipment will be
sterilized after use on the plant materials that are
suspected or known to be diseased. Cuts on plant
materials shall be made into the living tissues to induce
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23
callousing. Cut surface will be flat, sharp and without
jagged or torn edges.
Pruning shall be done in such a manner as not to change
the natural habitat or special shape of the trees. Pruning
operation will consider carefully the natural growth
pattern of branches on the tree, palm or shrub. Tree
branches will be pruned back to the collar at the base
of the branch.
8.6.3 Tree guards
Where tree guards are necessary, care should be taken
to ensure that they do not impede natural movement
or restrict growth.
8.6.4 Nursery Stock
Planting should be carried out as soon as possible after
reaching the site. Where planting needs to be delayed,
care should be taken to protect the plants from pilfering
or damage from people or animals. Plants with bare
roots should be heeled-in as soon as received or
otherwise protected from drying out, and others set
closely together and protected from the wind. If
planting needs to be delayed for more than a week,
packed plants should be unpacked, the bundles opened
up and each group of plants heeled-in separately and
clearly labelled. If for any reason the surface of the
roots becomes dry the roots should be thoroughly
soaked before planting.
8.6.5 Protective Fencing
According to local environment shrubs shall be
protected adequately from vandalism until established.
8.6.6 Routine Maintenance Work Schedule
Operation
i) Watering
ii) Weeding
in) Edging
iv) Fertilizing
a) Trees/palms
b) Shrubs/ground
covers
c) Grass
v) Loosening of soil
vi) Control of pest by
applying appropriate
insecticides
vii) Control of disease by
applying appropriate
fungicides.
Frequency
Checking all planting
areas and pits and water
as often as necessary to
ensure that planting
material does not dry out
Monthly
Monthly
Once every three months
Monthly
Once every three months
Monthly
Fortnighdy
Monthly, increasing the
frequency to fortnighdy
during rainy season
Operation
viii) Grass cutting
ix) Pruning and shaping
trees/palms
x) Staking
xi) Trimming shrubs/
ground covers
Frequency
Fortnighdy
Once every six month for
small and low sagging
branches
As and when required.
Monthly or as when
required
8.6.7 Clean-Up Works
There shall be areas designated by landscape architect
for the contractor to carry out clean-up works. These
shall include the following:
a) Removal of dead and/or overhanging
branches of existing trees, palms, shrubs and
groundcovers.
b) Removal of any garbage and unsightly foreign
materials.
c) Removal of dead vines and plant materials.
The contractor shall prevent damages to the existing
plant materials, identified to be conserved. The plant
materials that are to be conserved if damaged beyond
use during the clean-up operations, the contractor shall
be liable to replace the plant materials at their own
expense.
8.6.8 Restoration
The contractor is responsible for the use of all materials,
labour and equipments and any injury to the plant
material, labour and equipment will be repaired or the
same replaced by the contractor at his own expense.
8.6.9 Completion
On completion, the ground shall be formed over and
left tidy.
9 SERVICE UTILITIES IN LANDSCAPE
9.1 Designed integration of structures and elements
related to external services (underground and over
ground utilities) with landscape is most essential for
any outdoor space.
The following services generally are the subject of
design co-ordination work for external areas:
a) Storm water drainage
1 ) Storm water network;
2) Open drain and swale;
3) Subsurface drainage system;
4) Catch basin and manholes;
5) Culvert and bridge;
6) Percolation pits;
7) Water harvesting units;
8) Retention walls and tanks;
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NATIONAL BUILDING CODE OF INDIA
9) Connection of all service lines up to out-
fall; and
10) Other related structures.
b) Sewage disposal system
1 ) Sewerage network;
2) Manholes, inspection chambers and
grease trap;
3) Septic tank, soak-pits, sewage treatment
plant and root zone unit;
4) Solid waste management units;
5) Connection of all service lines up to out-
fall; and
6) Other related structures.
c) Water supply
1 ) Water supply network;
2) Inspection chamber and valve chamber;
3) Water tank and treatment plant;
4) Tube well, bore well and associated
pump houses, etc; and
5) Service lines, elements associated with
water features and pools.
d) Fire lines
1 ) Yard hydrant lines ;
2) Yard or fire hydrants and hose reel box;
3) Fire water tank and pumps; and
4) Inspection chamber and valve chamber.
e) Electrical works
1) Electrical network;
2) Light fixtures for road, pedestrian paths;
special landscape features and building
facade;
3) Inspection chambers, junction boxes and
feeder pillars;
4) Electric poles, high voltage lines and
towers;
5) Transformer, substation and distribution
box; and
6) Other related structures.
f) Telephone and under ground cable network
1) Telephone network;
2) Inspection chambers;
3) Telephone poles, transmission towers; and
4) Other related structures.
g) Fuel and gas line
1) Supply network;
2) Inspection chamber and valve chamber;
3) Fuel tank and gas tank; and
4) Other related structures.
9.1.1 The following guidelines shall be applied for the
designed integration of external services networks and
elements in the landscape proposal:
a) The manholes and inspection chamber covers
for all external services should be adequately
designed for the live load (pedestrian or
vehicular) and the top finish level has to be
in alignment or flushed with the pavement or
finished ground level. The alignment of these
structures should be such that it is in geometric
perpendicular or parallel with adjacent
building or landscape lines. This would
facilitate easy and unobstructed movement
for pedestrians and increase the accessibility
for wheelchair users in public place and
also aid the landscape geometry to be
maintained.
b) Fire hydrants should be prominently located
and integrated with the landscape. Aesthetically
designed fire hose cabinet with clear access
as per statutory norms for fire safety, to be
located in geometric relation with adjacent
building or landscape lines. These structures
should not be a hindrance to vehicular or
pedestrian movement.
c) Irrigation hydrants should be unobtrusively
located and generally at the edge of shrub
planting and additionally in close proximity
to a drainage chamber or catch basin to avoid
waterlog. Hydrants should not be located
inside the chamber to minimize waterlog from
leaking pipes causing various health related
hazards. Hydrants should be located 200 mm
above the ground level.
d) Landscape lighting is a specialized activity
and illumination consultant or designer
should develop the landscape lighting plan
taking into consideration energy saving
measures, safety aspects, lighting pollution
and illumination level. Light fixtures are an
important part of street furniture and it is
advisable to use pole mounted light fixtures
for public landscape than bollards that are
prone to vandalism and damage.
e) Water body and fountains in public spaces
should have filtration facility to avoid health
hazards related to stagnant water. The piping
should be concealed and the pump room,
balancing tank and all other service structures
to be designed as an integral part of landscape.
f) Storage facilities for inflammable liquid fuel
and gas should be designed as a integral part
of the landscape and should be housed in
designed enclosures taking into consideration
all statutory norms these structures are
subjected to.
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 1 LANDSCAPE.
25
g) All underground service lines have to be well
coordinated and stacked appropriately in the
design stage to avoid overlaps and marked
with indicators above the ground for ease in
maintenance and servicing. Underground
service stacks should be generally aligned in
soft areas with no tree plantation, this would
facilitate easy maintenance without disrupting
the hard surface.
h) Designed facade for service structures that are
above the ground in external areas is advisable
so as to assist in developing aesthetically
pleasing exterior environment. Such structures
should be designed in a modular way so that
it would be part of the street furniture.
10 PAVED SURFACES IN EXTERNAL AREAS
The paved areas that are used for movement of
vehicles, pedestrians, and wheel chair users in outdoor
environment have to be designed to facilitate easy
accessibility, with well drained surface, and good visual
clues achieved with varied colour and texture of
finishing materials. The following guidelines may be
applied for the design of paved outdoor spaces:
a) Roads should provide clear access to fire
fighting vehicles, ambulance, sanitation
vehicles, etc and also allow safe movement
for vehicles, pedestrians and wheel chair
users.
b) Kerbs are required on all roads to adequately
control drainage within the road, prevent
moisture from entering the sub-grade,
separate the road from the pedestrian area, and
provide adequate lateral support for the
pavement structure.
c) Pedestrian circulation path consists of
sidewalks, wheelchair ramp, and landings.
Pathways of minimum width 1.50 m are
required along the length of road for any
public or private building where pedestrian
traffic is excepted.
d) Path way should be physically separated by
means of kerb, graded separation, barrier,
railing, or other means. The cross slope of
sidewalk will not exceed two percent. The
longitudinal slope of path should not exceed
1 in 20, unless the longitudinal slope of the
road exceeds this maximum, in that case the
standards that conform to a ramp should be
applied.
e) Benches, shelters, poles, signs, bus stops, etc
should be located on edge of the sidewalk with
clear minimum width of 1 .20 m for circulation
path.
f) All ramps should have minimum width of
1.20 m, excluding edge protection. The cross
slope of ramp should not exceed 1 in 50. And
longitudinal slope of ramp should not
exceed 1 in 12. All ramps should have an
unobstructed level landing both at top and
bottom of the ramp. The landing should have
the minimum width as the ramp. The landing
should be minimum 1.50 m in length. Any
ramp beside the road should be located in such
a way so that vehicles cannot park blocking
the access.
g) Handrail would be required for any ramp with
greater vertical height than 300 mm to prevent
pedestrians and wheelchair users slipping
from the ramp. The height of the top handrail
should be 900 mm from the top surface of the
ramp. The ramp surface should be rough
finished. All ramp and landing should be
designed so that water does not collect on the
surface of the ramp or landing.
h) Stone not less than 40 mm in thickness should
be used as paving finish in external areas.
Adequate slope and drainage facility to be
considered for all external paved surface
integrating it with the pavement design.
j) Smooth finish is not recommended for
external areas except to convey any design
concept.
k) Change in levels and steps may be depicted
in different texture or colour as a visual
clue.
11 STREET FURNITURE
The design elements for outdoor spaces may be
classified under the following categories:
a) Pavement and other pedestrian movement
spaces, covering
1) Footpath with heavy pedestrian traffic,
2) Footpath with light pedestrian traffic,
3) Plaza and public assembly spaces,
4) Kerb to footpath, and
5) Steps and ramps.
b) Parking and vehicular movement corridor,
covering
1 ) Parking unit,
2) Median and road divider,
3) Road marking, and
4) Speed breaker.
c) Traffic management units, covering
1) Bollards,
2) Barriers,
26
NATIONAL BUILDING CODE OF INDIA
d)
e)
f)
3)
Crash guard,
4)
Gate/ Access control,
5)
Vehicular height restrictors, and
6)
Traffic separators.
Outdoor public conveniences, covering
1)
Seating,
2)
Drinking fountains, and
3)
Toilet/Wash rooms.
Shelter and kiosks, covering
1)
Bus shelters,
2)
Police booth,
3)
Telephone booth,
4)
Milk booth/Food stall,
5)
Florist,
6)
Information desk, and
7)
Snack and coffee stall.
Outdoor illumination, covering
1)
Street light,
2)
Facade light, and
3)
Bollard light.
g) Tree protection units, covering
1) Tree guard,
2) Tree grate, and
3) Planter.
h) Garbage collection units, covering
1) Litter bin, and
2) Spittoons.
j) Service utilities, relating to
1) Water supply network,
2) ' Storm water network,
3) Sewerage network*
4) Electrical network,
5) Telephone lines,
6) Cable e-net, and
7) Gas.
k) Display and Signage
Location of the street furniture has to
coordinate with the traffic flow pattern of
vehicles and pedestrians and external services.
Some typical street furniture are given
in Fig. 3.
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 1 LANDSCAPE.
27
2000
5
ELEVATION
I I
ELEVATION
TREE GRILL
PLAN
All dimensions in millimetres.
3A BARRIER — FENCE AND BOLLARD COMBINATION
Fig. 3 Typical Street Furniture — Continued
28
NATIONAL BUILDING CODE OF INDIA
m
k^t
3B KIOSK
ill
W
~m
w
■W x>>
3C LIGHT POLE
3D PARK LIGHT
3E SIGNAGE
Fig. 3 Typical Street Furniture
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 1 LANDSCAPE
29
NATIONAL BUILDING CODE OF INDIA
PART 10 LANDSCAPING, SIGNS AND OUTDOOR
DISPLAY STRUCTURES
Section 2 Signs and Outdoor Display Structures
BUREAU OF INDIAN STANDARDS
CONTENTS
FOREWORD
1 SCOPE
2 TERMINOLOGY
3 PERMITS
4 MAINTENANCE AND INSPECTION
5 TYPES OF SIGNS
6 GENERAL REQUIREMENTS FOR ALL SIGNS
7 ELECTRIC SIGNS AND ILLUMINATED SIGNS
8 GROUND SIGNS
9 ROOF SIGNS
10 VERANDAH SIGNS
11 WALL SIGNS
12 PROJECTING SIGNS
13 MARQUEE SIGNS
14 SKY SIGNS
15 TEMPORARY ADVERTISING SIGNS, TRAVELLING CIRCUS SIGNS,
FAIR SIGNS AND DECORATIONS DURING PUBLIC REJOICING
16 ADDITIONAL GUIDELINES FOR SIGNS IN URBAN AND RURAL AREAS
17 ENVIRONMENTAL GRAPHICS FOR CITY SCAPE
ANNEX A SPECIMEN FORM FOR APPLICATION FOR PERMIT TO ERECT,
RE-ERECT OR ALTER ADVERTISING SIGN
LIST OF STANDARDS
5
5
6
13
13
13
18
18
19
19
20
20
20
21
21
22
23
23
24
NATIONAL BUILDING CODE OF INDIA
National Building Code Sectional Committee, CED 46
FOREWORD
This Section covers the requirements of signs and outdoor display structures with regard to public safety, structural
safety and fire safety. With the growing industrialization followed by urbanization of large number of cities and
towns, the advertising signs and its appurtenant structures had increased. In the absence of any definite rules, the
display of advertising signs had proceeded unrestrained resulting in a city or town littered indiscriminately with
hoardings and advertising signs of all types. Consideration of the aspects of urban aesthetics and public safety,
pointed to the necessity for building regulations for the control of advertising signs and structures.
This Section was, therefore, published in 1970 as Part 10 of the Code and was subsequently revised in 1983. In
the first revision, comments and suggestions received during its use were incorporated. As a result of experience
gained in implementation of 1 983 version of this Section and feedback received, a need to revise this Section was
felt. In the existing version of the Code, Part 10 is titled as Signs and Outdoor Display Structures. Now, this Part
has been enlarged to also cover Landscaping, This Part is therefore, being brought out in two sections, namely
Section 1 Landscape Planning and Design and Section 2 Signs and Outdoor Display Structure. This revision as
Section 2 Signs and Outdoor Display Structure has, therefore, been prepared to take care of the need to update
the same. The significant changes incorporated in this revision include:
a) Few more terminologies related to signs have been added.
b) Few explanatory figures have been added.
c) Guidelines for signs in urban and rural areas have been introduced.
d) Guidelines for environmental graphics for the city scape have been introduced.
The provisions of this Section are without prejudice to the regulations already in vogue in areas requiring special
controls in harmony with their historical monuments/environment.
For signs coming on highways, relevant IRC rules shall apply. In this connection reference is made to
'IRC 46 : 1972 A policy on road advertisements'.
All standards, cross-referred to in the main text of this Section, are subject to revision. The parties to agreement
based on this Section are encouraged to investigate the possibility of applying the most recent editions of the
standards.
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 2 SIGNS.
NATIONAL BUILDING CODE OF INDIA
PART 10 LANDSCAPING, SIGNS AND OUTDOOR
DISPLAY STRUCTURES
Section 2 Signs and Outdoor Display Structures
1 SCOPE
This Section covers the requirements with regard to
public safety, structural safety and fire safety of all
signs and outdoor display structures.
2 TERMINOLOGY
2.0 For the purpose of this Section, the following
definitions shall apply.
2.1 Signs
2.1.1 Abandoned Sign — A sign structure that has
ceased to be used, and the owner intends no longer to
use the same, for the display of sign copy, or as
otherwise defined by state law.
2.1.2 Advertising Sign — Any surface or structure with
characters, letters or illustrations applied thereto and
displayed in any manner whatsoever out of doors for
purposes of advertising or to give information
regarding or to attract the public to any place, person,
public performance, article or merchandise whatsoever,
and which surface or structure is attached to, forms
part of or is connected with any building, or is fixed to
a tree or to the ground or to any pole, screen, fence or
hoarding or displayed in space.
2.1.3 Banner — A flexible substrate on which copy
or graphics may be displayed.
A sign utilizing a banner as its
2.1.4 Banner Sign
display surface.
2.1.5 Canopy Sign — A sign affixed to the visible
surface(s) of an attached or freestanding canopy.
2.1.6 Closed Sign — An advertising sign in which at
least more than fifty percent of the area is solid or
tightly enclosed or covered.
2.1.7 Combination Sign — A sign that is supported
partly by a pole and partly by a building structure.
2.1.8 Direction Sign — Usually included with an
arrow and used for indicating a change in route or
confirmation to a correct direction.
2.1.9 Electric Sign — An advertising sign in which
electric fittings, which are an integral part of the signs,
are used.
2.1.10 Exterior Sign — Any sign placed outside a
building.
2.1.11 Freestanding Sign — A sign principally
supported by a structure affixed to the ground, and not
supported by a building, including signs supported by
one or more columns, poles or braces placed in or upon
the ground.
2.1.12 Ground Sign — An advertising sign detached
from a building, and erected or painted on the ground
or on any pole, screen, fence or hoarding and visible
to the public.
2.1.13 Identification Sign — A sign that gives specific
location information, identifies specific items, for
example, Parking Lot B, Building No. 5, First Aid,
etc.
2.1.14 Illuminated Sign — An advertising sign,
permanent or otherwise, the functioning of which
depends upon its being illuminated by direct or indirect
light, and other than an electric sign.
2.1.15 Informational Sign — Used for overall
information for general organization of a series of
elements that is, campus plan, bus route, building
layout, shopping mall plan, etc.
2.1.16 Mansard — An inclined decorative roof-like
projection that is attached to an exterior building
facade.
2.1.17 Marquee Sign — An advertising sign attached
to or hung from a marquee canopy or other covered
structure projecting from and supported by the building
and extending beyond the building wall, building line.
2.1.18 Open Sign — An advertising sign in which at
least fifty percent of the enclosed area is uncovered or
open to the transmission of wind.
2.1.19 Parapet ~ A low wall or railing built along
the edge of a roof or floor.
2.1.20 Portable Sign — Any sign not permanently
attached to the ground or to a building or building
surface.
2.1.21 Projecting Sign — An advertising sign affixed
to any building element and projecting more than
300 mm therefrom.
2.1.22 Regulatory Sign — Sign that gives operational
requirements, restrictions or gives warnings, usually
used for traffic delineation or control, for example
'Stop', 'No Parking', 'One Way', etc.
2.1.23 Roof Sign — An advertising sign erected or
placed on or above the parapet or any portion of a roof
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 2 SIGNS...
of a building including signs painted on the roof of a
building.
2.1.24 Sky Sign — An advertising sign displayed in
space like:
a) a gas filled balloon anchored to a point on
the ground and afloat in the air with or without
a streamer of cloth, etc; or
b) sky-writing, that is, a sign or word traced in
the atmosphere by smoke discharged from an
aeroplane.
2.1.25 Sign — Any device visible from a public place
that displays either commercial or non-commercial
messages by means of graphic presentation of
alphabetic or pictorial symbols or representations. Non-
commercial flags or any flags displayed from flagpoles
or staffs shall not be considered as signs.
2. 1 .26 Sign A rea — The area of the smallest geometric
figure, or the sum of the combination of regular
geometric figures, which comprise the sign face. The
area of any double-sided or 'V shaped sign shall be
the area of the largest single face only. The area of a
sphere shall be computed as the area of a circle. The
area of all other multiple-sided signs shall be computed
as 50 percent of the sum of the area of all faces of the
sign.
2.1.27 Sign Copy — Those letters, numerals, figures,
symbols, logos and graphic elements comprising the
content or message of a sign, exclusive of numerals
identifying a street address only.
2.1.28 Sign Face — The surface upon, against or
through which the sign copy is displayed or illustrated,
not including structural supports, architectural features
of a building or sign structure, non- structural or
decorative trim, or any areas that are separated from
the background surface upon which the sign copy is
displayed by a distinct delineation, such as a reveal or
border.
2.1.29 Sign Structure — Any structure supporting a
sign.
2.1.30 Temporary Sign — An advertising sign, banner
or other advertising device constructed of cloth, canvas,
fabric or any other light material, with or without a
structural frame, intended for a limited period of
display; including decorative displays for holidays or
public demonstrations.
2.1.31 VERANDAH Sign — An advertising sign
attached to, posted on or hung from a VERANDAH.
2.1.32 Wall Sign — An advertising sign, other than a
projecting sign, which is directly attached to or painted
or pasted on the exterior surface of or structural element
of any building.
2.1.33 Window Sign — A sign affixed to the surface
of a window with its message intended to be visible to
and readable from the public way or from adjacent
property.
2.2 General
2.2.1 Approved — Approved by the Authority having
jurisdiction.
2.2.2 Area of Special Control — Any area declared
an area of special control by the Authority in respect
of the display of advertising signs, where the
requirements for such display are more restrictive than
elsewhere in the area controlled by the Authority.
2.2.3 Authority Having Jurisdiction — The Authority
which has been created by a statute and which for the
purpose of administering the Code/Part, may authorize
a committee or an official to act on its behalf;
hereinafter called the 'Authority'.
2.2.4 Building Line — The line up to which the plinth
of a building adjoining a street or an extension of a
street or on a future street may lawfully extend. It
includes the lines prescribed, if any, in any scheme.
2.2.5 Combustible Material — A material is combustible,
if it burns or adds heat to a fire when tested for non-
combustibility in accordance with good practice
[10-2(1)].
2.2.6 Owner — Person or body having a legal interest
in land and/or building thereon. This includes free
holders, leaseholders or those holding a sub-lease
which both bestows a legal right to occupation and
gives rise to liabilities in respect of safety or building
condition.
In case of lease or sublease holders, as far as ownership
with respect to the structure is concerned, the structure
of a flat or structure on a plot belongs to the allottee/
lessee till the allotment/lease subsists.
2.2.7 Street Line — The line defining the side limits
of a street.
3 PERMITS
3.1 Application
3.1.1 Conditions for Grant of Permit
No sign shall be erected, altered or maintained without
first obtaining a permit for the same from the Authority
and shall be subjected to the following conditions:
a) The written permission shall not be granted
or renewed at any one time, for a period
exceeding three years from the date of grant
of such permission or renewal.
b) The written permission or the renewal granted
by the Authority shall become void:
NATIONAL BUILDING CODE OF INDIA
1) if any sign or the part thereof falls
either through an accident or any other
causes;
2) if any addition is made except for the
purpose of making it secure under the
direction of the Authority;
3) if any change is made in the sign or part
thereof;
4) if any addition or alteration is made to
the building or structure upon or over
which the sign is erected and if such
addition or alteration involves disturbance
of the sign or any part thereof; and
5) if the building or structure upon or over
which the sign is erected fixed or
restrained becomes demolished or
destroyed.
c) Light and ventilation of buildings, if any
situated near the signs and hoardings shall not
be obstructed in any way;
d) Advertisements displayed shall not be of
any objectionable or obscene nature given
in 3.3;
e) In the public interest the Authority shall have
the right to suspend the licence even before
the expiry period, upon which the licencee
shall remove the signs;
f) The licencee shall be responsible for the
observance of all the rules and regulations laid
down by the Authority;
g) The signs should not mar the aesthetic beauty
of the locality;
h) The signs other than pertaining to building
shall not be permitted to come in front of
buildings such as hospitals, educational
institutions, public offices, museums, buildings
devoted to religious worship and buildings of
national importance;
j) Maintenance and inspection of advertising
signs and their supports shall be as given
in 4.
k) No hoarding sign on the highways shall be
put without the permission of the Authority
maintaining/incharge of flyovers, highways/
roads; and
m) In addition all signs shall conform to the
general requirements given in 6.
n) The signs shall not be nailed or tied to trees
or any other woody vegetation.
3.1.2 Application for Licence or Permit and Required
Drawings
Every person intending to erect, alter or display an
advertising sign for which a permit or licence is
required, shall make application to the Authority on
the prescribed form containing such particulars as the
Authority may require. Such a form {see Annex A)
shall be signed by the applicant and by the owner of
the site upon which such sign is or is to be situated and
shall include the following information:
a) Full specifications showing the length, height
and weight of the sign, the location where it
is to be erected, the manufacturer's name and
address and where applicable, the number of
lights and electrical details of the same.
b) Such form shall be accompanied by a location
plan indicating the position of the sign on the
site drawn to a scale of 1:500 and by full detail
drawing drawn to a scale of 1 : 20 or an exact
multiple thereof in ink or on prints including,
if required by the Authority, an elevation
showing the sign in relation to the fagade.
c) In the case of roof signs, projecting signs or
ground signs in addition to the foregoing, the
size of all members of supporting frameworks
and anchorages, and, if required by the
Authority, the necessary design calculations
shall be furnished with the application.
d) Any other particulars as may be desired by
the Authority covered in 6.
e) In the case of sky signs, necessary information
as desired by the Authority may be supplied.
3.1.3 The Authority may, on the receipt of an
application for permit, either sanction or refuse such a
permit or sanction with modifications as deemed
necessary and shall communicate decision to the
applicant. If within 30 days or receiving an application
for a permit the Authority fails to intimate in writing
to the applicant, the permit along with the plans shall
be deemed as sanctioned.
3.1.4 When a sign has to be altered, information only
on such plans and statements, as may be necessary,
shall be included in the form. However, the changing
of movable parts of an approved sign that is designed
for such changes, shall not be deemed an alteration
provided the conditions of the original approval and
the requirements of this part are not violated.
3.1.5 Existing Advertising Signs
Advertising signs in existence at the date of
promulgation of the Code and covered by a valid
licence or permit issued by the Authority shall not
require to be licensed under the Code until such licence
or permit has expired, provided it is maintained in a
good and safe condition.
3.1.6 For advertising signs application shall be
submitted through a structural engineer along with
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 2 SIGNS ...
necessary drawings and structural calculations. The
wind load taken in the design calculations shall be in
accordance with Part 4 'Structural Design, Section 1
Loads, Forces and Effects'.
3.2 Exemptions
3.2.1 No permit shall be required for signs and outdoor
display structures of the following types:
a) If the signs are exhibited within the window
of any building provided it does not affect
light and ventilation of the building.
b) If it relates to the trade or business carried
on within the land or building upon which
such advertisement is exhibited or to any
sale, entertainment or meeting or lettering
of such land or building or any effects
therein; or to the trade or business carried
on by the owner of any tramcar, omnibus
or other vehicle upon which such
advertisements is exhibited, provide d it is not
more than 1 .2 m 2 .
c) In addition no permission shall be required
for the signs covered in 3.2.2 to 3.2.5. Such
exemptions, however shall not construed to
relieve the owner of the sign from the
responsibility of erection and maintenance in
compliance with the Code.
3.2.2 Wall Signs
The wall signs listed in 3.2.2.1 to 3.2.2.3 shall not
require a permit.
3.2.2.1 Store signs
Non-illuminated signs erected over a show window or
over the door of a store or business establishment which
announce the name of the proprietor and the nature of
the business conducted therein; the sign shall not be
more than 1 m in height and the width of the business
establishment.
3.2.2.2 Government building signs
Signs erected on a municipal, state or central
government building which announce the name, nature
of the occupancy and information.
3.2.2.3 Name plates
Any wall sign erected on a building or structure
indicating the name of the occupant of building, which
is not more than 0.5 m 2 in area.
3.2.3 Ground Signs
3.2.3.1 Transit directions
The erection or maintenance of a sign designating the
location of a transit line, a rail track, station or other
public carrier when not more than 0.5 m 2 in area.
3.2.3.2 Highway Signs
In general, advertisements of the following classes
are permissible without permission though these
should reasonably conform to the principles set out
in 3.5.1:
Class (1) Functional Advertisements:
a) Official warning signs, traffic directions, sign
posting and notices or advertisements posted
or displayed by or under the directions of any
public or court officer in the performance of
his official or directed duties.
Example:
b)
DIVERSION AHEAD
Direction signs to places of public amenity,
such as petrol filling stations, hospitals, first-
aid posts, police stations and fire stations.
Example:
HOSPITAL
BUS STATION
c) Signs relating solely to any city, town, village
or historic place, shrine, place of tourist
interest:
Example:
ELLORA
CAVES
FARIDABAD
TOWN
d) Signs, notices, etc, erected by the Defence
Department for information of members of
the armed forces or the public.
Example:
ARTILLERY RANGE AHEAD
e) Signs restricting trespass of property, limited
to 0.2 m 2 in area or less.
Example:
PRIVATE
PROPERTY
TRESPASSERS
WILL BE
PROSECUTED
f) Signs or notices/0.2 m 2 in area or less, placed
so as to show direction to a residence
and planted sufficiently away from the
carriageway.
Class (2) Advertisements Relating to the Premises on
which these are Displayed:
a) Advertisements for the purpose of identification,
direction or warning with respect to the land
or building on which they are displayed,
provided not exceeding 0.2 m 2 in area in the
case of any such advertisement.
8
NATIONAL BUILDING CODE OF INDIA
Examples:
Example:
MIND
THE STEP
PROPERTY OF
MOHAN LAL
&CO
USHA
KIRAN
b)
Advertisements relating to any person,
partnership or company separately carrying
on a profession, business trade at the premises
where any such advertisement is displayed;
limited to one advertisement not exceeding
0.3 m 2 in area in respect of each such person,
partnership or company.
Example:
RAM LAL & COMPANY
c)
Advertisements relating to any institution of
a religious, educational, cultural, recreational,
medical or similar character or any hotel,
public house, dark bungalow, block of flats,
club, boarding house or hostel situated on the
land on which any such advertisement is
displayed; limited to one advertisement not
exceeding 1.2 m 2 in area in respect of each
such person, partnership or company.
Examples:
COLLEGE OF
ENGINEERING
HOLJDLAY
HOUSE
ROTARY CLUB
Class (3) Advertisements of Temporary Nature
a)
Advertisements relating to the sale or letting
of the land on which they displayed; limited
in respect of each such sale or letting to one
advertisement not exceeding 2 m 2 in area.
Examples:
TO LET
HOUSE FOR SALE
b)
Advertisements announcing sale of goods or
livestock, and displayed on the land where
such goods or livestock are situated or where
such sale is held, limited to one advertisement
not exceeding 1.2 m 2 in area.
Examples:
SALE THIS
WEEK
CATTLE SALE
c)
Advertisements relating to the carrying out
of building or similar work on the land
on which they displayed exceeding 2 m 2 in
CAUTION EXCAVATION
IN PROGRESS
d)
Advertisements announcing any local event
of a religious, educational, cultural, political,
social or recreational character, not being
an activity promoted or carried on for
commercial purposes; limited to a display of
advertisements occupying an area not
exceeding 0.6 m 2 on any premises.
Examples:
DIWALIMELA
FLOWER SHOW
area.
3.2.4 Temporary Signs
3.2.4.1 Construction site signs
Construction signs, engineers' and architects' signs and
other similar signs which may be authorized by the
Authority in connection with construction operations
(see Table 1).
3.2.4.2 Special displays signs
Special decorative displays used for holidays, public
demonstrations or promotion of civic welfare or
charitable purposes, on which there is no commercial
advertising, provided that the Authority is not held
responsible for any resulting damage (see 15.2.2).
3.2.5 The qualitative requirements of signs given in
Table 1 shall not require any permit.
3.3 Unsafe and Unlawful Signs
3.3.1 Notice of Unsafe and Unlawful Signs
When any sign becomes insecure, or in danger of
falling, or otherwise unsafe, or if any sign shall be
unlawfully installed, erected or maintained in violation
of any of the provisions of the Code, the owner thereof,
or the person or firm maintaining the same, shall upon
written notice of the Authority, forthwith in the case
of immediate danger and in any case within not more
than three days, make such sign conform to the
provisions of this part or shall'remove it. If within three
days the order is not complied with, the Authority may
remove such sign at the expense of the owner.
3.3.1.1 Notwithstanding the above, it shall be the
responsibility of the owner to ensure the safety of the
advertising signs, even without a reference from the
Authority. The owner shall also ensure to remove the
remnant structures of the abandoned sign.
3.3.2 The following signs may not be permitted under
any circumstances:
Any sign which in the opinion of the Authority is an
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 2 SIGNS ...
I
r
w
e
n
8
Table 1 Advertising Signs for Which No Permit or Licence is Required
(Clause 3.2.5)
Class (with Sample)
Area of Each Separate Maximum Height
Sign (or Aggregate) Above Ground
Floor Level to
Top of Sign
(1)
(2)
(3)
Illumination
Provided
(4)
Description of Sign
Number
Permitted
(5)
Maximum
Dimension of
Letters, Symbols,
etc
(6)
1) Functional signs of certain
authorities statutory
undertakings, public
transport undertakings, and
fire rigades, etc
2) Miscellaneous signs relating
to premises on which they
are displayed
a) Identification, direction,
or warning
b) Person partnership or
company carrying
profession business, or
trade; name or private
person
c) Relating to any
institution of a religious,
educational, cultural, or
medical character; name
of building or premises
3) Temporary signs (cloth
banners)
a) Signs relating to the sale
or letting off the land
(within the site of the
building) on which they
are displayed
BUS
STATION
X-RAY
UNIT
MIND THE
STEP
CHAWLA &
CO. LTD.
S. BOSE
COLLEGE OF
COMMERCE
XYZ FLATS
HOUSE FOR
SALE
As may be reasonably
required for the safe and
efficient performance of
the function
Not more than 4 m
Not more than 0.3 m 2
each
Not more than 1.2 m 2
each
Not more than 2,4 m 2
(ratio of width todeptfi
2:l)inaggre^tearea.
No sign to project more
than 1 m when displayed
on a building (within the
site)
As stated in col 2 As stated in col 2
Not more than 5 m
(in area of special
control 4 m)
Not more than 5 m
(in area of special
control 4 m)
Not more than 5 m
(in area of special
control 4 m)
Not more than 5 m
(in area of special
control 4 m)
Only to indicate that
medical or similar
services or supplies are
available on premises
where advertisement is
displayed*
Only to indicate that
medical or similar
services or supplies are
available on premises
where advertisement is
displayed*
Only to indicate that
medical or similar
services or supplies are
available on premises
where advertisement is
displayed*
None
As stated in col 2 As stated in col 2
Any number
One at each
entrance
One on each
frontage
Any number but
aggregate area
not to exceed that
given in col 2
Not more than
750 mm (in area
of special control
300 mm)
Not more than
750 mm (in area
of special control
300 mm)
Not more than
750 mm (in area
of special control
300 mm)
Not more than
750 mm (in area
of special control
300 mm)
Remarks
(7)
Shall not be display-
ed earlier than 28 days
before the sale or other
matter is due to start and
shall be removed within
14 days after the
conclusion of such sale
or matter
£
n
en
o
H
©
o
o
»
o
H
R
W3
W
D
H
o
2
W3
Table 1 — Concluded
Class (with Sample)
(1)
Area of Each Separate
Sign (or Aggregate)
(2)
Maximum Height
Above Ground
Floor Level to
Top of Sign
(3)
Illumination
Provided
(4)
b) Signs relating to the
carrying out of building
or similar operations on
the land where sign is
displayed
c) Signs announcing any
local event in connection
with an activity
promoted for non-
commercial purposes by
various local
organizations
d) Signs and business
premises for areas of
special control, signs
on business premises
with reference to the
business, the goods
sold, or the services
provided, etc, in
these premises and
the name and
qualifications of
the person carrying
on such activity
THIS FACTORY IS
BEING ERECTED
BYXYZ
CONSTRUCTION
CO.
Building and
Engineering
Contractor
Not more than 4 m
Not more than 5 m
(in area of special
control 4 m)
None
DIWALI MELA
Not more than 1.5 m 2
(in aggregate area 4 m)
XYZQR BANK
Not to exceed one-
twelfth of area of each
face up to a height
of 4 m
Not more than 5 m
(in area of special
control 4 m)
Not more than 4 m
None
Description of Sign
Remarks
Only to indicate that
medical or similar
services or supplies are
available where
advertisement is
displayed*
Number
Permitted
Maximum
Dimension of
Letters, Symbols,
etc
(5)
(6)
(7)
One for each
Not more than
road frontage for 750mm
eachontractoror (inareaof
sub-contractor special control
300 mm)
Any number but
aggregate area
not to exceed that
given in col 2 on
any premises
Any number but
aggregate area
not to exceed that
given in col 2
Not more than
750 mm (in area
of special control
300 mm)
Not more than
300 mm
May be displayed only
while such works are in
progress
Shall not be displayed
earlier than 28 days
before the event is due
to start and shall be
removed within 14 days
of its conclusion
Area to be computed as
if the advertisement
were laid flat against the
face of the building
* or where connected with danger.
obscene, repulsive, revolting, or objectionable
character or prejudicial to the municipality or savouring
political propaganda or of a nature calculated to
produce pernicious or injurious effect on public or any
particular class of persons, or is displayed in such a
place, in such a manner or by any such means as, in
the opinion of the Authority, could be likely to affect
injuriously the amenities of, or to disfigure any
neighbourhood.
3.4 Area of Special Control
3.4.1 Whenever in the opinion of the Authority it is
likely that any advertising device otherwise permitted
in terms of the Code may affect injuriously or disfigure
any particular area within the jurisdiction of the
Authority it may proclaim such area as an area of
special control. Parks and land for public use may also
be included as areas of special control.
3.4.2 Subject to the provisions of 3.4.1 within such
area, the erection and display of any advertising sign
shall be prohibited or restricted in any manner deemed
necessary by the Authority. The Authority shall publish
its intention of proclaiming such an area in one or more
newspapers circulating in the area of jurisdiction of
the Authority. Any owner of property within such area
who may feel aggrieved by such proclamation may
appeal within one month from such publication against
proclamation of such an area to the Authority whose
decision shall be final.
3.4.3 The wording on any VERANDAH sign, permitted
by the Authority, in any area of special control, shall
be restricted to the name of the proprietor or firm
occupying the premises, the name of the building or
institution, the general business or trade carried on,
such as 'JEWELLER', 'CAFE', 'DANCING', or
information regarding the location of the building
entrance, box office or regarding the theatre programme
or similar information. No VERANDAH sign in any
area of special control shall advertise any particular
article of merchandise nor shall any such sign refer to
price or reduction in price.
3.4.3.1 Normally no other advertising sign shall,
except as for 3.4.3, be within a distance of 30 ni from
the area of special control.
3.5 Prohibition of Advertising Signs on Certain Sites
Where the Authority is of the opinion that any site is
unsuitable for display of advertising signs by virtue of
the general characteristics of the locality in regard to
historic, architectural, cultural or similar interest, or
by virtue of its position, the display of such signs is
likely to affect in any way the safety of any form of
transport, erection of advertising signs on such a site
shall be prohibited.
3.5.1 Highways and Roads
In general the following advertisements should not be
permitted:
a) At or within 100 m of any road junction,
bridge or railway crossing or another crossing.
In urban areas, this distance may be reduced
to 50 m, provided there is no conflict with
the requirements stated further on;
NOTE — The safe stopping distance for a vehicle
travelling at a speed of 50 km/h is 60 m. This should be
the 'uninfluenced distance' for a driver approaching a
junction. Assuming that 3 seconds is the time during
which the influence of an advertisement board persists,
the distance travelled in this time will be about 40 m.
The sign should, therefore, be more than 100 m away
from the junction. Hence 100 m is suggested.
b) In such manner and at such places as to
obstruct or interfere with the visibility of
approaching, merging or intersecting traffic;
c) Within 10 m of the edge of a carriageway;
NOTE — A distance of 10 m may be taken as the
normal minimum setback from the edge of the
carriageway, the maximum area of the advertisement
being 0.3 m 2 for every metre of setback.
d) Within 50 m along the road, of any sign board
erected for the regulation of traffic under the
orders of a Public Authority, such as a Traffic
Authority, a Public Transport Authority, or a
Local Authority;
e) In such a form as will obscure or hinder
interpretation of any sign, signal or other
device erected for traffic control by the Public
Authorities. For instance, the advertisements
should not imitate or resemble, in colour or
shape, the standard legal traffic signs, or
employ such words as 'STOP' in the same
manner as used on traffic signs;
f) On boards, placards, cloth banners or sheets
(except traffic signs) hung across a road as
they distract the attention of driver and are,
therefore, hazardous;
NOTE — Any advertisement allowed on the sides of a
foot over bridge or flyover across the carriage-ways
shall be restricted in size and shape such that no part of
the advertisement bQ&rd projects beyond the top, bottom
and sides of the parapet of foot over bridge or flyover.
g) In such form as will obstruct the path of
pedestrians and hinder their visibility at
crossings;
h) Within right-of-way of the road; and
j) When these will affect local amenity.
3.5.2 Illuminated advertisements of the following
description are objectionable from the angle or traffic
safety and should not be allowed:
a) Advertisements which contain, include or are
12
NATIONAL BUILDING CODE OF INDIA
illuminated by any flashing, intermittent or
moving light or lights except those giving
public service information, such as time,
temperature, weather or date;
b) Illuminated advertisements of such intensity
or brilliance as to cause glare or impair vision
of the driver or pedestrians, or which
otherwise interfere with any operations of
driving; and
c) Advertisements illuminated in such a way as
to obscure or diminish effectiveness of any
official sign, device or signal.
4 MAINTENANCE AND INSPECTION
4.1 Maintenance
All signs for which a permit is required, together with
all their supports, braces, guys and anchors shall be
kept in good repair, both structurally and aesthetically,
and when not galvanized or constructed of approved
corrosion-resistive non-combustible materials, shall be
painted when necessary to prevent corrosion.
4.2 Housekeeping
It shall be the duty and responsibility of the owner of
every sign to maintain the immediate premises occupied
by the sign, in a clean, sanitary and healthy condition.
4.3 Inspection
Every sign for which a permit has been issued and
every existing sign for which a permit is required shall
be inspected by the Authority at least once in every
calendar year.
5 TYPES OF SIGNS
In this part, the following types of signs are covered
[see also a few explanatory figures of general sign types
(Fig. 1 A), comparison of roof and wall or fascia sign
(Fig. IB) and sign area computation methodology
(Fig. ICand ID)].
a) Electric and illuminated signs (see 7);
b) Ground signs (see 8);
c) Roof signs (see 9);
d) VERANDAH signs (see 10);
e) Wall signs (see 11);
f) Projecting signs (see 12);
g) Marquee signs (see 13);
h) Sky signs (see 14); and
j) Miscellaneous and temporary signs (see 15).
6 GENERAL REQUIREMENTS FOR ALL SIGNS
6.1 Loads
Every advertising sign shall be designed so as to
withstand safely the wind, dead, seismic and other
loads as set out in Part 6 'Structural Design, Section 1
Loads, Forces and Effects'.
6.2 Illumination
No sign shall be illuminated by other than electrical
means and electrical devices and wiring shall be
installed in accordance with the requirements of Part 8
'Building Services, Section 2 Electrical and Allied
Installations' . In no case, shall any open spark or flame
be used for display purposes unless specifically
approved by the Authority.
6.3 Design and Location of Advertising Signs
a) Sign should not obstruct any pedestrian
movement, fire escape, door or window,
opening used as a means for egress or fire
fighting purposes.
b) No sign shall in any form or manner interfere
with openings required for light and
ventilation.
c) When possible signs should be gathered
together into unified systems. Sign clutter
should be avoided in the landscape.
d) Signs should be combined with lighting
fixture to reduce unnecessary posts and for
ease of illuminating the signs.
e) Information signs should be placed at natural
gathering spots and included in the design of
sight furniture.
f) Placement of sign should be avoided where
they may conflict with pedestrian traffic.
g) Sign should be placed to allow safe pedestrian
clearance vertically and latterly.
h) Braille strips may be placed along sign edges
or raised letters may be used for readability
for the blind and partially sighted.
j) No sign shall be attached in anyway to a tree
or shrub.
6.4 Use of Combustibles
6.4.1 Ornamental Features
Wood or plastic or other materials of combustible
characteristics similar to wood may be used for
mouldings, cappings, nailing blocks, letters and
latticing where permitted and for other purely
ornamental features of signs.
6.4.2 Sign Facings
Sign facings may be made of approved combustible
materials provided the area of each face is not more
than 10 m 2 and the wiring for electric righting is entirely
enclosed in metal conduit and installed with a clearance
of not less than 5 cm from the facing material.
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 2 SIGNS.
13
CITY
MEDICAL
CENTRE
THE
PIZZA
HOUSE
DELHI
UNIVERSITY
MONUMENT OR BLADE PYLON POLE GROUND OR LOW PROFILE
COMMON FREESTANDING SIGN TYPE
SHOE SHOPPE
I
CAMERAS
SWEET CORNER
■Mil
MUSIC LAND
CLOTHING
M
WALL OR FASCIA SIGNS ON STOREFRONTS
ALL INDIAN SPORTS GOODS
ROOF SIGN
CANOPY SIGN ON FREESTANDING CANOPY
1A GENERAL SIGN TYPES
Fig. 1 Typical Examples of Sign Type — Continued
PROJECTING
SIGN
14
NATIONAL BUILDING CODE OF INDIA
MAIN ROOF;
-SIGN
CO
z
o
CO
u_
o
o
CO
z
O
\-
o
LU
—y
o
Q_
LU
o
o
z
o
CO
z
CO
<
o
CO
<
SLOPING ROOF
MOUNT
1 ROOF SIGN 1
1 I
FLAT EAVE
MOUNT
MAIN ROOF;
Z
CANOPY
SIDE ELEVATION
SIGN
I NOT ROOF SIGN 1
CANOPY
MOUNT
MAIN ROOF
z
SIDE ELEVATION
SIGN
JNOT ROOF SIGNE
MANSURD
MOUNT
MAIN ROOF
z
-SIGN
PENT EAVE
SIDE ELEVATION
PENT EAVE
MOUNT
1 B COMPARISON - ROOF AND WALL OR FASCIA SIGNS
Fig. 1 Typical Examples of Sign Type — Continued
PART 10 LANDSCAPING, SIGNS AND OUTDOOR EfclSPLAY STRUCTURES — SECTION 2 SIGNS
15
CENTRAL
THE
PIZZA
HOUSE
V-
COMMUNITY CENTRE
SHOP
j:
I
HEALTH CLUB
i
i
SPORTING LIFE
SIGN STRUCTURES
+
CITY
MEDICAL
CENTRE
SIGN
STRUCTURE
WITH ROUTED
AREA OF
SIGN COPY
4 REVEAL
CITY
MEDICAL
CENTRE
SIGN
STRUCTURE
WITH INDIVIDUAL
SURFACE
APPLIED
GRAPHIC AND
LETTERS
COMPUTE SUM
OF AREA
AROUND
ELEMENTS
NOTE — Sum of shaded areas only represent sign area. Sign constructed with panels or cabinets.
1C SIGN AREA - COMPUTATION METHODOLOGY
Fig. 1 Typical Examples of Sign Type — Continued
16
NATIONAL BUILDING CODE OF INDIA
SYNDICATE
CITY BRANCH
COMPUTE AREA AROUND
COPY ELEMENTS ONLY
COMPUTE AREA INSIDE .
DEFINED BORDER OR INSIDE ►
CONTRASTING COLOR AREA
SYNDICATE BANK
CITY BRANCH
ARROWHEAD
PARKING
COMPUTE SUM OF
AREAS OF INDIVIDUAL
ELEMENTS ON WALL OR
STRUCTURE
c
OMMUNITY
c
ENTRE
IN COMPUTING AREA FOR
UPPER AND LOWER CASE
LETTERING INCLUDE
ASCENDERS OR DESCENDERS,
BUT NOT BOTH. CALCULATE
SUPER ASCENDERS
SEPARATELY AS INDICATED
NOTE — Sum of shaded areas only represent sign area for compliance purposes. Signs consisting of individual letters,
elements or logos placed on building walls or structures.
1D SIGN AREA - COMPUTATION METHODOLOGY
Fig. 1 Typical Examples of Sign Type
6.5 Damage or Defacement by Removal
Advertising Signs
of
Whenever any advertising sign is removed, whether
in consequence of a notice or order under the Code
or otherwise, any damage or defacement to the
building or site on or from which such sign was
displayed, shall be made good to the satisfaction of
the Authority.
6.6 Alteration to Ground Level
Whenever any alteration is made to the ground level
adjacent to any advertising sign, the owner of the site
on which sign is erected, shall be responsible for the
alteration of the height of such sign so as to conform
to the requirements of this Section.
6.7 Traffic Control Interference
No advertising sign shall be erected or maintained
which interferes with or is likely to interfere with any
sign or signal for the control of traffic.
6.7.1 No advertising sign shall be placed particularly
in bends and curves so as to obstruct the view of traffic
at intersecting streets.
6.8 Draining of Signs
Adequate provision for drainage shall be made in every
advertising sign, where the possibility of collection of
moisture exists.
6.9 Glass in Signs
All glass used in advertising signs, other than glass
tubing used in gas discharge or similar signs, shall be
of safety glass conforming to accepted standards
[10-2(2)] at least 3 mm thick. Glass panels in
advertising signs shall not exceed 6 m 2 in area, each
panel being securely fixed in the body of the sign
independently of all other panels. Glass signs shall be
properly protected from the possibility of damage by
falling objects by the provisions of suitable protecting
metal canopies, or by other approved means. Use of
FART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 2 SIGNS...
17
glass may be discouraged or avoided wherever possible
for signs placed overhead.
6.10 Interference to Fire Hydrants
Advertising signs shall be so placed as not to obstruct
the use of the hydrants or other fire fighting
appliances.
6.11 Serving Devices
Ladders, platforms, hooks, rings and all other devices
for the use of servicing personnel shall have safety
devices and suitable design loadings (reference may
also be made to Part 7 * Constructional Practices and
Safety').
6.12 Animated Devices
Signs which contain moving section or ornaments shall
have fail-safe provisions to prevent the section or
ornaments from releasing and falling or shifting its
centre of gravity more than 450 mm. The fail-safe
device shall be in addition to the mechanism and its
housing which operate the movable section or
ornament. The fail-safe device shall be capable of
supporting the full dead weight of the section or
ornament when moving mechanism releases.
7 ELECTRIC SIGNS AND ILLUMINATED
SIGNS
7.1 Material for Electric Signs
Every electric sign shall be constructed of non-
combustible material except where the sign is purely a
flood-lit sign.
7.2 Installation of Electric Signs and Illuminated
Signs
Every electric sign and illuminated sign shall be
installed in accordance with Part 8 'Building Services,
Section 2 Electrical and Allied Installations'.
7.3 No illuminated sign in red, amber or green colour
shall be erected or maintained within a horizontal
distance of 10 m of any illuminated traffic sign.
7.4 All advertising signs illuminated by light other
than a white light at height of less than two storeys or
6 m above the footpath, whichever be the greater
height, shall be suitably screened so as to satisfactorily
prevent any interference with any sign or signal for
the control of traffic.
7.5 Intense Illumination
No person shall erect any sign which is of such intense
illumination as to disturb the residents in adjacent or
nearby residential buildings. Notwithstanding any
permission given for such erection, any such sign
which after erection is, in the opinion of the Authority,
of such intense illumination as to disturb the occupants
of adjacent or nearby buildings shall, on the order of
the Authority, be suitably altered or removed by the
owner of the site concerned within such reasonable
period as the Authority may specify.
7.6 Hours of Operation
No electric sign, other than those necessary in the
opinion of the Authority in the interest of public
amenity, health and safety, shall be operated between
midnight and sunrise.
7.7 Flashing, Occulting and Animated
No flashing, occulting or animated advertising signs,
the periodicity of which exceeds 30 flashes to the
minute, shall be erected so that the lowest point of such
signs is less than 9 m above the ground level.
7.8 For illuminated signs in the vicinity of airports,
the Directorate General of Civil Aviation should be
consulted.
8 GROUND SIGNS
8.1 Material
Every ground sign exceeding 6 m in height together
with frames, supports and braces shall be constructed
of non-combustible material except as in 6.4.
8.2 Dimensions
No ground sign shall be erected to a height exceeding
9 m above the ground. Lighting reflectors may extend
beyond the top or face of the sign.
8.3 Supports and Anchorage
Every ground sign shall be firmly supported and
acnchored to the ground. Supports and anchors shall
be of treated timber in accordance with good practice
[10-2(3)], or metal treated for corrosion resistance or
masonry or concrete.
8.4 Site Cleaning
The owner of any site on which a ground sign is erected
shall be responsible for keeping such part of the site as
is visible from the street, clean, sanitary, unoffensive
and free of all obnoxious substances and unsightly
conditions to the approval of the Authority.
8.5 Obstruction to Traffic
No ground sign shall be erected so as to obstruct free
access to or egress from any building.
8.6 Set Back
No ground sign shall be set nearer to the street line
than the established building line.
18
NATIONAL BUILDING CODE OF INDIA
8.7 Bottom Clearance
The bottom line of all ground signs shall be at least
0.6 m above the ground, but the intervening space may
be filled with open lattice work or platform decorative
trim.
8.8 Ground painted signs shall conform to the
requirements of 6 and 7 where applicable.
9 ROOF SIGNS
9.1 Material
Every roof sign together with its frames, supports and
braces, shall be constructed of non-combustible
material, except as in 6.4, Provision shall be made for
electric grounding of all metallic parts; and where
combustible materials are permitted in letters or other
ornamental features, all wiring and tubing shall be kept
free and insulated therefrom.
9.2 Dimensions
No roof sign shall exceed the following heights on
buildings of heights:
a)
b)
c)
Height of Building
Not exceeding four storeys or
18m
Height of Sign,
Max
storeys
but
or
not
Five to eight
exceeding 18 m
exceeding 36 m
Exceeding eight storeys or 36 m,
provided that in calculating the
height of such signs, signs placed
one above the other, or on planes
at different levels of the same
building shall be deemed to be
one sign, whether or not such
signs belong to different owners
2m
3m
5m
9.3 Location
a)
b)
No roof sign shall be so placed on the roof of
any building as to prevent free passage from
one part of the roof to another.
No roof sign shall be placed on or over the
roof of any building unless the entire roof
construction is of non-combustible material.
9.4 Projection
No roof sign shall project beyond the existing building
line of the building of which it is erected or shall extend
beyond the roof in any direction.
9.5 Supports and Anchorage
Every roof sign shall be thoroughly secured and
anchored to the building on or over which it is erected.
All loads shall be safely distributed to the structural
members of the building.
9.6 For roof signs near the airports the Directorate
General of Civil Aviation should be consulted.
9.7 Painted roof signs shall conform to the requirements
of 6 and 7, where applicable.
10 VERANDAH SIGNS
10.1 Material
Every verandah sign shall be constructed entirely of
non-combustible material except as in 6.4.
10.2 Dimensions
No VERANDAH sign exceed 1 m in height. No
VERANDAH sign hanging from a VERANDAH shall
exceed 2.5 m in length and 50 mm in thickness, except
that VERANDAH box signs measuring not more than
200 mm in thickness, measured between the principal
faces of the sign and constructed entirely of metal wired
glass may be erected.
10.3 Alignment
Every VERANDAH sign shall be set parallel to the
building line, except that any such sign hanging from
a VERANDAH shall be set at right angles to the building
line.
10.4 Location
VERANDAH signs, other than hanging signs only, shall
be placed in the following locations:
a) Immediately above the eaves of the
VERANDAH roof in such a manner as not to
project beyond the rear of the roof gutter;
b) Against but not above or below the
VERANDAH parapet or balustrade provided
such parapet or balustrade is solid and the
sign does not project more than 20 cm from
the outside face of such parapet or balustrade;
or
c) On the VERANDAH beams or parapets in the
case of painted signs.
10.5 Height of Hanging VERANDAH Signs
Every VERANDAH sign hanging from a VERANDAH
shall be fixed in such a manner that the lowest
point of such sign is not less than 2.5 m above the
pavement.
10.6 Projection
Except as provided for in 10.4, no VERANDAH sign
shall extend outside the line of the VERANDAH to
which it is attached.
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 2 SIGNS ...
19
11 WALL SIGNS
11.1 Material
Every wall sign exceeding 4 m 2 in area shall be
constructed of non-combustible material except as
in 6.4.
11.2 Dimensions
a) The total area of any wall sign shall not exceed
20 m 2 for every 1 5 m of building frontage to
the street to which such sign faces; except that
in the case of a wall sign, consisting only of
the name of a theatre or cinema, the total area
of such sign shall not exceed 200 m 2 .
b) No wall sign which exceeds 30 m 2 in area shall
be located on any wall not directly facing the
road; provided that any such sign or signs
shall not exceed 25 percent of the side wall
area visible from the street.
11.3 Projection
No wall sign shall extend above the top of the wall or
beyond the ends of the wall to which it is attached. At
any place where pedestrians may pass along a wall,
any wall sign attached thereto shall not project more
than 7.5 cm therefrom within a height of 2.5 m
measured from the level of such place.
11.4 Supports and Attachment
Every wall sign attached to walls shall be securely
attached. Wooden blocks or anchorage with wood used
in connection with screws, staples or nails shall not be
considered proper anchorage, except in the case of wall
signs attached to walls of wood.
12 PROJECTING SIGNS
12.1 Material
Every projecting sign and its support and framework
shall be constructed entirely of non-combustible
material.
12.2 Projection and Height
No projecting sign or any part of its supports or frame
work shall project more than 2 m beyond the building;
however it shall not project beyond the plot line facing
the street; when it projects into the street it shall be
at clear height of 2.5 m from the road (see Part 3
'Development Control Rules and General Building
Requirements'):
a) The axes of all projecting signs shall be at
right angles to the main face of the building.
Where a V-construction is employed for the
faces, the base of the sign against the building
shall not exceed the amount of the overall
projection.
b) No projecting signs shall extend above the
eaves of a roof or above the part of the
building face to which it is attached.
c) The maximum height of a projecting sign
shall be related to the height of the building
to which it is attached in the following
manners:
SI Height of Building
Height of Sign,
No.
Max
i) Not exceeding four
9 m
storeys or 18 m
ii) Five to eight storeys or
12 m
not exceeding 36 m
iii) Exceeding eight storeys
15 m
or 36 m
12.3 Supports and Attachment
Every projecting sign shall be securely attached to a
building so that movement in any direction is prevented
by corrosion-resistant metal brackets, rods, anchors,
supports, chains or wire ropes so designed and arranged
that half the number of such fixing devices may safely
support the sign under all circumstances.
12.3.1 Staples or nails shall not be used to secure any
projecting sign to any building.
12.4 Additional Loads
Projecting sign structures which could be used to
support an individual on a ladder or other servicing
device whether or not specifically designed for the
servicing device shall be capable of supporting the
anticipated additional load but in no case less than
500 kg concentrated horizontal load and 1 500 kg
vertical concentrated load applied at the point of
assumed loading or point of most eccentric loading.
The building component to which the projecting sign
is attached shall also be designed to support the
additional loads.
13 MARQUEE SIGNS
13.1 Materials
Marquee signs shall be constructed entirely of metal
or other approved non-combustible materials.
13.2 Height
Such sign shall not exceed 2 m in height nor shall they
project below the fascia of the marquee nor lower than
2.5 m above the footpath.
13.3 Length
Marquee signs may extend the full length but in no
case shall they project beyond the ends of the marquee.
20
NATIONAL BUILDING CODE OF INDIA
14 SKY SIGNS
14.1 In the case of the sky signs, the regulations laid
down by the Authority concerned shall apply.
15 TEMPORARY ADVERTISING SIGNS,
TRAVELLING CIRCUS SIGNS, FAIR SIGNS
AND DECORATIONS DURING PUBLIC
REJOICING
15.1 Types
None of the following advertising signs shall be erected
or maintained, other than as temporary signs erected
in accordance with 15.2:
a) Any advertising sign which is painted on or
fixed on to or between the columns of a
VERANDAH;
b) Any advertising sign which projects above or
below any fascia, bearer, beam or balustrade
of a VERANDAH or balcony;
c) Any advertising sign which is luminous or
illuminated and which is fixed to any fascia
bearer, beam or balustrade of any splayed
or rounded corner of a VERANDAH or
balcony;
d) Any streamer sign erected across a road;
e) Any sign not securely fixed so as to prevent
the sign swinging from side to side;
f) Any advertising sign made of cloth, paper
mache, or similar or like material but
excluding licensed paper signs on hoardings
or fences;
g) Any advertising sign on a plot used or
intended to be used exclusively for residential
purposes, other than a brass plate or board
preferably not exceeding 600 mm x 450 mm
in size, affixed to the fence or entrance door
or gate of a dwelling, and in the case of a block
of flats, affixed to the wall of the entrance
hall or entrance door of any flat; and
h) Any sign on trees, rocks, hillsides and similar
natural features.
15.2 Requirements for Temporary Signs
15.2.1 All temporary advertising, travelling circus and
fair signs and decorations during public rejoicing shall
be subject to the approval of the Authority and shall
be subjected to the approval of the Authority and shall
be erected so as not to obstruct any opening and to
minimize fire risk.
15.2.2 The advertisement contained on any such sign
shall pertain only to the business, industry or other
pursuit conducted on or within the premises on which
such sign is erected or maintained. Temporary
advertising signs shall be removed as soon as torn or
damaged and in any case within 14 days after erection
unless extended.
15.2.3 The Authority shall be empowered to order
the immediate removal of any temporary advertising
sign or decoration, where, in its opinion such action
is necessary in the interests of public amenity and
safety.
15.2.4 Pole Signs
Pole signs shall be constructed entirely of non-
combustible materials and shall conform to the
requirements for ground or roof signs as the case may
be (see 8 and 9). Such signs may extend beyond the
street line if they comply with the provisions for
projecting signs (see 12).
15.2.5 Banner and Cloth Signs
Temporary signs and banners attached to or suspended
from a building, constructed of cloth or other
combustible material shall be strongly constructed and
shall be securely attached to their supports. They shall
be removed as soon as torn or damaged, and in no
case later than 14 days after erection; except, that
permits for temporary signs suspended from or attached
to a canopy or marquee shall be limited to a period of
10 days.
15.2.6 Maximum Size
Temporary signs shall not exceed 10 m 2 in area.
15.2.7 Projection
Temporary signs of cloth and similar combustible
construction shall not extend more than 300 mm over
or into a street or other public space except that such
signs when constructed without a frame may be
supported flat against the face of a canopy or marquee
or may be suspended from the lower fascia thereof but
shall not extend closer to the footpath than 2.5 m.
15.2.8 Special Permits
All temporary banners suspended from building or
hung on poles, which extend across streets or other
public spaces shall be subject to special approval of
the Authority.
15.2.9 Bill boards set up by the Authority shall be used
for temporary signs, symbols, bills for entertainment,
etc, so that other walls of the city are not defaced.
15.2.9.1 Bills for entertainment and other functions
shall not be affixed on to building walls other than
the bill boards (see 15.2.9). The organization
responsible for such bills and posters shall be held
responsible for any such defacement and non-removal
of signs.
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 2 SIGNS .
21
16 ADDITIONAL GUIDELINES FOR SIGNS IN
URBAN AND RURAL AREAS
16.1 Erecting maintaining and owning signs in rural
areas shall be encouraged so as to boost the information
and economic status of the rural population.
16.2 The tolerance criteria for the permission granted
towards putting up any signs for any urban area shall
be as given in 16.2.1 to 16.2.4.
16.2.1 Small Towns
The traffic hazards in small towns are few and the
defacement due to excessive advertising signs has not
occurred. Therefore, orderly development of signs may
enliven the town environment and boost the economy.
The tolerance here may be high. The following
guidelines may be followed for signage:
a) Advertising Sign — Electric sign, ground sign,
building sign, illuminated sign, sky sign and
temporary sign are permissible.
b) Directional Sign — Electric sign, ground sign,
building sign, illuminated sign and temporary
sign are permissible while sky sign is not
permissible.
c) Informational Sign — Electric sign, ground
sign, building sign, illuminated sign and
temporary sign are permissible while sky sign
is not permissible.
d) Identification Sign — Electric sign, ground
sign, building sign, illuminated sign and
temporary sign are permissible while sky sign
is not permissible.
e) Regulatory Sign — Electric sign, ground sign,
illuminated sign and temporary sign are
permissible while building sign and sky sign
are not permissible.
16.2.2 Medium Towns
The traffic hazards in medium towns are few and the
defacement due to excessive advertising signs has not
occurred. Proper design, erection and maintenance of
the signs shall be encouraged. The following guidelines
may be followed for signage:
a) Advertising Sign — Electric sign, ground sign,
building sign, illuminated sign, sky sign and
temporary sign are permissible.
b) Directional Sign — Electric sign, ground sign,
illuminated sign are permissible while
building sign, sky sign and temporary sign
are not permissible.
c) Informational Sign — Electric sign, ground
sign, illuminated sign, and temporary sign are
permissible while building sign and sky sign
are not permissible.
d) Identification Sign — Electric sign, ground
sign, building sign, illuminated sign and
temporary sign are permissible while sky sign
is not permissible.
e) Regulatory Sign — Electric sign, ground sign,
illuminated sign and temporary sign are
permissible while building sign and sky sign
are not permissible.
16.2.3 Large Cities
The traffic is high and hazards of accidents are many
in large cities. Defacement of buildings, roads and the
urban spaces due to advertisements has to be checked.
Therefore, the permissivity and tolerance for erecting
signs is very low. The following guidelines may be
followed for signage:
a) Advertising Sign — Electric sign, ground sign,
illuminated sign and sky sign are permissible
while building sign and temporary sign are
not permissible.
b) Directional Sign — Ground sign, illuminated
sign are permissible while electric sign,
building sign, sky sign and temporary sign
are not permissible.
c) Informational Sign — Ground sign, illuminated
sign, building sign and temporary sign are
permissible while electric sign and sky sign
are not permissible.
d) Identification Sign — Electric sign, ground
sign, building sign, illuminated sign and
temporary sign are permissible while sky sign
is not permissible.
e) Regulatory Sign — Ground sign, illuminated
sign and temporary sign are permissible while
electric sign, building sign and sky sign are
not permissible.
16.2.4 Mega and Metro Cities
The traffic hazards in mega and metro cities are many
and the defacement due to excessive advertising signs
has marred the urban environment. The density of
population is very high and the danger of greater loss
of life due to disasters is Self evident. Therefore, the
permissivity for erecting signs is very low and no
tolerance exists for law breakers. The following
guidelines may be followed for signage:
a) Advertising Sign — Electric sign, ground sign,
illuminated sign and sky sign are permissible
while building sign and temporary sign are
not permissible.
b) Directional Sign — Ground sign, illuminated
sign are permissible while electric sign,
building sign, sky sign and temporary sign
are not permissible.
22
NATIONAL BUILDING CODE OF INDIA
c) Informational Sign — Ground sign, illuminated
sign and temporary sign are permissible while
electric sign, building sign and sky sign are
not permissible.
d) Identification Sign — Electric sign, ground
sign, building sign, illuminated sign and
temporary sign are permissible while sky sign
is not permissible.
e) Regulatory Sign — Ground sign, illuminated
sign and temporary sign are permissible while
electric sign, building sign and sky sign are
not permissible.
17 ENVIRONMENTAL GRAPHICS FOR CITY
SCAPE
17.1 The urban environment may be susceptible to
confusion and chaos due to improper graphics,
hoardings and advertisements. Therefore, the signage
should be installed following requisite guidelines laid
down keeping the functional, safety and aesthetic
aspects in view.
The scale of the project should also be considered for
implementing signage design. In urban design/planning
projects and landscape projects on a large scale, the
following criteria should be followed for signs and
outdoor display structures:
a) The aesthetic and harmonious development
of the visual environment.
b) Signage for the handicapped at all grade
changes, entry points to buildings and public
conveniences and facilities. Braille strips used
should be displayed not above 1.5 m height
for the benefit of the visually impaired at all
important nodes, entrances and routes. Ramps
for the people on wheelchair should be
highlighted with the appropriate international
sign of the wheelchair. These need to be
lighted adequately even for night time.
c) Environmental graphics should be creatively
designed to cater to the basic function of
information, identity and way finding,
with the objective of improvement of urban
scape.
d) Safety aspects.
e) Protection of trees and other vegetation from
harm due to signs.
ANNEX A
(Clause 3.1.2)
SPECIMEN FORM FOR APPLICATION FOR PERMIT TO ERECT,
RE-ERECT OR ALTER ADVERTISING SIGN
1 . Type of sign
2. *Location:
a) Building/premises
b) Location of building/premises with respect to neighbouring streets.
3. *Dimensions and details of the sign
4. Materials used for different parts
5. *Electrical and lighting details
6. * Structural details showing also supporting framework and anchorages
7. Mode of operation
* Plans as desired in 3.1.2(b) are enclosed.
Name and address of the applicant
Name and address of the owner of the
building/premises
Signature .
Date
Signature .
Date
PART 10 LANDSCAPING, SIGNS AND OUTDOOR DISPLAY STRUCTURES — SECTION 2 SIGNS .
23
LIST OF STANDARDS
The following list records those standards which are IS No. Title
acceptable as 'good practice' and 'accepted standards' (1) 3808:1979 Method of test for non-
in the fulfillment of the requirements of this Code. The combustibility of building
latest version of a standard shall be adopted at the time materials (first revision)
of enforcement of the Code. The standards listed may (2) 2553 Specification for safety glass:
be used by the Authority as a guide in conformance (Part X) . 1990 General purpose (third revision)
with the requirements of the referred clauses in the (Part 2) . m2 For road transport
(3) 401 : 2001 Code of practice for preservation
of timber (fourth revision)
24 NATIONAL BUILDING CODE OF INDIA
BUREAU OF INDIAN STANDARDS
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