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Full text of "ICC 400 (2007): Standard on the Design and Construction of Log Structures"

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NOTICE OF INCORPORATION 

United States Legal Document 

$3T All citizens and residents are hereby advised that 
this is a legally binding document duly incorporated by 
reference and that failure to comply with such 
requirements as hereby detailed within may subject you 
to criminal or civil penalties under the law. Ignorance of 
the law shall not excuse noncompliance and it is the 
responsibility of the citizens to inform themselves as to 
the laws that are enacted in the United States of America 
and in the states and cities contained therein. ~^k 

* * 



ICC 400 (2007), Standard on the Design and 
Construction of Log Structures, as incorporated 
and mandated by the State of Wisconsin, 
Chapter SPS 321, Construction Standards, 
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ICC 400-2007 

American Notional Standard 




STANDARD ON 

THE DESIGN AND 

CONSTRDCTION OF 

LOG STRDCTDRES 



ICC 400-2007 

American Notional Standard 




INTERNATIONAL 
CODE COUNCIL® 



International Code Council 

500 New Jersey Avenue, NW, 6th Floor 

Washington, D.C. 20001 



Approved February 8, 2007 

American National Standard Institute 
25 West 43rd Street 
New York, NY 10036 



2007 ICC Standard on the Design and Construction of Log Structures 
(ICC 400-2007 IS LOG) 



First Printing: April 2007 

Second Printing: April 2008 

Third Printing: December 2009 



First Published: April 2007 



ISBN-1 0:1-58001-534-4 
ISBN-13: 978-1-58001-534-9 



Copyright © 2007 



by 

International Code Council, Inc. 



ALL RIGHTS RESERVED. This 2007 ICC Standard on the Design and Construction of Log Structures (ICC-400-2007 IS LOG) is 
a copyrighted work owned by the International Code Council, Inc. Without advance written permission from the copyright owner, 
no part of this book may be reproduced, distributed, or transmitted in any form or by any means, including, without limitation, elec- 
tronic, optical or mechanical means (by way of example, and not limitation, photocopying, or recording by or in an information stor- 
age retrieval system). For information on permission to copy material exceeding fair use, please contact: Publications, 405 1 W. 
Flossmoor Road, Country Club Hills, IL 60478. 



Trademarks: "ICC," the "International Code Council" logo and "Standard on the Design and Construction of Log Structures' 
(ICC-400-2007 IS LOG) are trademarks of the International Code Council, Inc. 



PRINTED IN THE U.S.A. 



American 

National 

Standard 



Approval of an American National Standard requires verification by ANSI that the requirements for due process, consensus, and 
other criteria for approval have been met by the standards developer. 

Consensus is established when in the judgement of the ANSI Board of Standards Review, substantial agreement has been reached 
by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily 
unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made toward their resolu- 
tion. 

The use of American National Standards is completely voluntary; their existence does not in any respect preclude anyone, whether 
he or she has approved the standards or not, from manufacturing, marketing, purchasing, or using products, processes, or proce- 
dures not conforming to the standards. 

The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any 
American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American 
National Standard in the name of the American National Standards Institute. Requests for interpretations should be addressed to the 
secretariat or sponsor whose name appears on the title page of this standard. 

CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American 
National Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw this standard. Purchasers of 
American National Standards may receive current information on all standards by calling or writing the American National Stan- 
dards Institute. 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



iv STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



FOREWORD 

Introduction 

In 2003, upon direction from the ICC Board of Directors, the ICC Standards Council appointed a consensus committee to develop a 
standard to cover the design and construction of log structures. 

Development 

This is the first edition of the International Code Council® (ICC®) Standard on the Design and Construction of Log Structures. This 
standard was developed by the ICC Consensus Committee on Log Structures (IS-LOG) that operates under ANSI Approved ICC 
Consensus Procedures for the development of ICC standards. ICC is approved by ANSI as an Accredited Standards Developer. 

The meetings of the IS-LOG Consensus Committee were open to the public and interested individuals and organizations from 
across the country participated. Views and objections were solicited through several public comment periods. All views and objec- 
tions were considered by the consensus committee and an effort was made toward their resolution. A vote by the consensus commit- 
tee approved this standard. 

The technical content of currently published codes and documents on log construction was reviewed and considered by the commit- 
tee. While there were many similarities among the practices and documents reviewed, there were marked philosophical differences 
that were considered by the committee. The requirements in ICC 400 are based on the intent to establish provisions consistent with 
the scope of the ICC family of codes and standards that adequately protect public health, safety and welfare; provisions that do not 
necessarily increase construction costs; provisions that do not restrict the use of new materials, products or methods of construction. 

Adoption 

ICC 400, Standard on the Design and Construction of Log Structures is available for adoption and use by jurisdictions internation- 
ally. Its use within a governmental jurisdiction is intended to be accomplished through adoption by referenced in accordance with 
proceedings establishing the jurisdiction's law. At the time of adoption, jurisdictions should insert the appropriate information in 
provisions requiring specific local information, such as the name of the jurisdiction. 

Formal Interpretations 

Requests for Formal Interpretations on the provisions of ICC 400-2007 should be addressed to: ICC, Chicago District Office, 405 1 
West Flossmoor Road, Country Club Hills, IL 60478. 

Maintenance - Submittal of Proposals 

All ICC standards are revised as required by ANSI. Proposals for revising this edition are welcome. Please visit the ICC website at 
www.iccsafe.org for the official "Call for Proposals" announcement. A proposal form and instructions can also be downloaded 
from www.iccsafe.org. 

ICC, its members and those participating in the development of ICC 400-2007 do not accept any liability resulting from compliance 
or noncompliance with the provisions of ICC 400-2007. ICC does not have the power or authority to police or enforce compliance 
with the contents of this standard. Only the governmental body that enacts this standard into law has such authority. 

International Code Council Consensus Committee on Log Structures (IS-LOG) 

Consensus Committee SCOPE: The Consensus Committee (CC) on Log Structures (IS-LOG) shall have primary responsibility 
for minimum requirements to safeguard the public health, safety and general welfare through design, construction and installation 
requirements for log and heavy timber structures. 

This standard was processed and approved for submittal to ANSI by the ICC Consensus Committee on Log Structures (IS-LOG). 
Committee approval of the standard does not necessarily imply that all committee members voted for its approval. 

Representatives on the Consensus Committee are classified in one of three voting interest categories. The committee has been 
formed in order to achieve consensus as required by ANSI Essential Requirements. At the time it approved this standard, the 
IS-LOG Consensus Committee consisted of the following members: 

General Interest (G) - User Interest (U) - Producer Interest (P) 

Edwin J. Burke (U), University of Montana, Missoula, Montana 

Randy Kaatz (U), American Institute of Building Design, Bend, Oregon 

Elyse G. Levy, S.E. (U), Self, Munster, Indiana 

Ann Marie Long (G), Clark County Building Department, Las Vegas, Nevada 

Rob Pickett, Chair (P), Log Homes Council, NAHB, Hartland, Vermont 

Joseph C. Folker (Alternate P), Log Homes Council, NAHB, Lewisburg, Pennsylvania 

STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES v 



FOREWORD 



Robert Savignac, Vice-Chair (P), International Log Builders Association, Lumby, British Columbia 

Robert Chambers (Alternate P), International Log Builders Association, River Falls, Wisconsin 

John "Buddy" Showalter (P), American Forest & Paper Association, Washington, D.C. 

David P. Tyree (Alternate P), American Forest & Paper Association, Colorado Springs, Colorado 

Craig Springe (G), La Plata County, Durango, Colorado 

Mark Stimac (G), City of Troy, Troy, Michigan 

Sharon Walter (Alternate G), City of Highland, Highland, Illinois 

Committee Secretary: Marc Nard, CBO, Senior Technical Staff, Codes & Standards, International Code Council, Country Club 
Hills, Illinois 



Voting Membership in Each Category 



Category 


Number 


General-(G) 


3 


User-(U) 


3 


Producer-(P) 


3 


TOTAL 


9 



Interest Categories 

General Interest: Individuals assigned to the General Interest category are those who represent the interests of an entity, including 
an association of such entities, representing the general public, or entities that promulgate or enforce the provisions within the com- 
mittee scope. These entities include consumers and government regulatory agencies. 

User Interest: Individuals assigned to the User Interest category are those who represent the interests of an entity, including an 
association of such entities, which is subject to the provisions or voluntarily utilizes provisions within the committee scope. These 
entities include academia, applied research laboratory, building owner, design professional, government non-regulatory agency, 
insurance company, private inspection agency, and product certification/evaluation agency. 

Producer Interest: Individuals assigned to the Producer Interest category are those who represent the interests of an entity, includ- 
ing an association of such entities, which produces, installs, or maintains a product, assembly, or system subject to the provisions 
within the committee scope. These entities include builder, contractor, distributor, labor, manufacturer, material association, stan- 
dards promulgator, testing laboratory and utility. 

NOTE — Multiple Interests: Individuals representing entities in more than one of the above interest categories, one of which is a 
Producer Interest, are assigned to the Producer Interest. Individuals representing entities in the General Interest and User Interest 
categories are assigned to the User Interest. 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



TABLE OF CONTENTS 
CHAPTER 1 ADMINISTRATIVE PROVISIONS . . 1 

Section 

101 Administrative Provisions 

102 Applicability 

103 Provisions For Compliance 

104 Compliance Alternatives 

105 Conventions 

106 Inspections 

107 Foundations 

108 Design Loads 

109 Referenced Documents 2 

CHAPTER 2 DEFINITIONS 3 

Section 

201 General 3 

202 Defined Terms 3 

203 Symbols 4 

CHAPTER 3 GENERAL REQUIREMENT 5 

Section 

301 General 5 

302 Materials 5 

303 Fire-Resistance Ratings Of Logs and 

Log Assemblies 38 

304 Provisions For Settling In Log Structures 39 

305 Thermal Envelope 42 

CHAPTER 4 STRUCTURAL PROVISIONS 45 

Section 

401 General 45 

402 Prescriptive Provisions 45 

403 Engineered Provisions 45 

404 Connections 46 

405 Floor Systems 47 

406 Log Walls 47 

407 Roof Systems 48 

CHAPTER 5 REFERENCED STANDARDS 49 

STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



CHAPTER 1 

ADMINISTRATIVE PROVISIONS 



SECTION 101 
ADMINISTRATIVE PROVISIONS 

101.1 Scope. This standard establishes the minimum require- 
ments for log structures to safeguard the public health, safety 
and welfare through structural, thermal, and settling provi- 
sions. This standard is intended for adoption by local govern- 
mental agencies and organizations setting model codes to 
achieve uniformity in technical design criteria in building 
codes and other regulations. 



SECTION 102 
APPLICABILITY 

102.1 Applicability. The construction of new log structures 
shall comply with this standard. 



SECTION 103 
PROVISIONS FOR COMPLIANCE 

103.1 Provisions for compliance. This standard provides the 
minimum design requirements for the construction of log 
structures. In lieu of these provisions, or where these provi- 
sions are not applicable, accepted engineering methods and 
practices in accordance with the appropriate sections of the 
International Building Code or the International Residential 
Code as applicable for the intended use of the structure shall be 
permitted to be used. Structural elements that meet the applica- 
bility provisions of Section 102, but are not within the limits of 
the design provisions of this Standard shall be designed in 
accordance with the appropriate sections of the International 
Building Code or the International Residential Code as 
applicable. 



104.1.2 Tests. Whenever there is insufficient evidence of 
compliance with the provisions of this standard, or evidence 
that a material or method does not conform to the require- 
ments of this standard, or in order to substantiate claims of 
alternative materials or methods, the building official shall 
have the authority to require tests as evidence of compliance 
to be made at no expense to the jurisdiction. Test methods 
shall be as specified in this code or by other recognized test 
standards. In the absence of recognized test methods, the 
building official shall approve the testing procedures. Tests 
shall be performed by an approved agency. Reports of such 
tests shall be retained by the building official for the period 
required for retention of public records. 



SECTION 105 
CONVENTIONS 

105.1 Conventions. Dimensions that are not stated as "maxi- 
mum or minimum" are absolute. All dimensions are subject to 
conventional industry standard. 



SECTION 106 
INSPECTIONS 

106.1 Inspections. During the course of the construction the 
code official is authorized to make all of the necessary inspec- 
tions, or the code official shall have the authority to accept 
reports of inspections by approved agencies or individuals. 
Reports of such inspections shall be in writing and be certified 
by a responsible officer of such approved agency or by the 
responsible individual. The code official is authorized to 
engage such expert opinion deemed necessary to report upon 
unusual technical issues that arise. 



SECTION 104 
COMPLIANCE ALTERNATIVES 

104.1 Alternative material, design and methods of con- 
struction and equipment. The provisions of this standard are 
not intended to prevent the installation of any material or to 
prohibit any design or method of construction not specifically 
prescribed by this standard, provided that any such alternative 
has been approved. An alternative material, design or method 
of construction shall be approved where the building official 
finds that the proposed design is satisfactory and complies with 
the intent of the provisions of this standard, and that the mate- 
rial, method of work offered is, for the purposes intended, at 
least the equivalent of that prescribed in this standard in quality, 
strength, effectiveness, fire resistance, durability and safety. 

104.1.1 Evaluation reports. Supporting data, where neces- 
sary to assist in the approval of materials or assemblies not 
specifically provided for in this standard, shall consist of 
valid evaluation reports from approved sources. 



SECTION 107 
FOUNDATIONS 

107.1 Foundations. Foundations systems shall be designed in 
accordance with the appropriate sections of the International 
Building Code or the International Residential Code as appli- 
cable for the intended use of the structure. 



SECTION 108 
DESIGN LOADS 

108.1 Design Loads. Loads and load combinations shall be in 
accordance with the provisions of this section. 

108.2 Loads. Loads applied to log structures shall be in accor- 
dance with the International Building Code. 

Exception: For log structures used as one- and two-family 
dwellings and their accessory structures, loads shall be per- 
mitted to be determined in accordance with AF&PA's Wood 
Frame Construction Manual (WFCM) for One- and 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



ADMINISTRATIVE PROVISIONS 



Two-Family Dwellings, or the International Residential 
Code. 

108.3 Load combinations. Load combinations applied to log 
structures shall be in accordance with the International Build- 
ing Code. 

Exception: For log structures used as one- and two- family 
dwellings, load combinations shall be permitted to be deter- 
mined in accordance with the International Residential 
Code. 

108.4 Dead loads due to self-weight. Dead loads due to self 
weight of logs shall be in accordance with the provisions of this 
section. 

108.4.1 Gravity loads. The weight of logs used to deter- 
mine dead loads for calculating foundation and other sup- 
port conditions shall be based on log profile (size), wood 
species (density), and either service moisture content in 
accordance with Section 302.2.2.2 or design moisture con- 
tent in accordance with Section 302.2.2.1 whichever is 
greater. 

108.4.2 Uplift resistance. The weight of logs used to deter- 
mine dead loads for resisting uplift forces shall be based on 
the minimum calculated service moisture content deter- 
mined in Section 302.2.2.2. 



SECTION 109 
REFERENCED DOCUMENTS 

109.1 Reference documents. The codes and standards 
referenced in this standard shall be considered part of the 
requirements of this standard to the prescribed extent of each 
such reference. Chapter 5 contains a complete list of all 
referenced standards. 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



CHAPTER 2 

DEFINITIONS 



SECTION 201 
GENERAL 

201.1 General. For the purpose of this standard, the terms 
listed in this chapter have the indicated meaning. 

201.2 Undefined terms. The meaning of terms not specifically 
defined in this document or in referenced standards shall have 
ordinarily accepted meanings such as the context implies. 

201.3 Interchangeability. Words, terms and phrases used in 
the singular include the plural and the plural include the singular. 



SECTION 202 
DEFINED TERMS 

ASPECT RATIO, BUILDING. The ratio of maximum build- 
ing plan dimension to minimum building plan dimension. 

ASPECT RATIO, SHEAR WALL. The ratio of the wall 
height-to-length (h:l) of a shear wall. The shear wall height is 
the maximum clear height from the top of the foundation or 
floor diaphragm to the diaphragm attachment at the top of the 
shear wall. 

BOTTOM PLATE, LOG (STARTER LOG). The first log 
course in a log wall resting on the subfloor. 

BUCK (ROUGH BUCK). A component of a system used to 
form an opening in a log wall. 

CANTILEVER. The unsupported portion of a bending mem- 
ber that extends beyond a support. 

CEILING JOIST, LOG. A horizontal structural framing 
member which supports ceiling or attic loads. 

CHECK(ING). A radial crack in the log that occurs as the 
wood is seasoning; separation of wood cells along the grain as a 
result of uneven shrinkage (differential tension and compres- 
sion stresses in the wood structure); a natural and unpredictable 
result of the seasoning process that generally does not affect the 
structural integrity of the log. 

CONTINUOUS LOAD PATH. The interconnection of fram- 
ing elements of the lateral and vertical force resisting systems, 
which transfers lateral and vertical forces to the foundation, 

CONTINUOUS SPAN. The span of a structural member 
between three or more supports. 

COPE (COVE, LONG GROOVE, LATERAL 
GROOVE). The longitudinal groove cut on a log that transfers 
loads from one log to the next by creating bearing surfaces on 
either side of the cope and has little or no flat bearing surfaces. 

COUNTERFLASHING. A flashing which, when applied 
over the regular flashing, allows for settling of the structure and 
slippage at the flashing connection, while still maintaining a 
weatherproof seal. 



COURSE OF LOGS (ROUND, LAYER). One complete 
layer of logs in the structure's shape; raising the height of the 
walls by one round of logs. 

DIAPHRAGM. A horizontal or sloped system acting to trans- 
mit lateral forces to the vertical resisting elements. 

DIAPHRAGM CHORD. A diaphragm boundary element per™ 
pendicular to the applied lateral load that is assumed to be placed 
in tension or compression due to the diaphragm moment in a 
manner similar to the flanges of a beam. When the term "dia- 
phragm" is used, it shall include horizontal bracing systems. 

FLOOR JOIST, LOG. A horizontal structural framing mem- 
ber which supports floor loads. 

GRADE PLANE. A reference plane representing the average 
of finished ground level adjoining the building at exterior 
walls. Where the finished ground level slopes away from the 
exterior walls, the reference plane shall be established by the 
lowest points within the area between the building and the lot 
line or, where the lot line is more than 6 feet (1829 mm) from 
the building, between the building and a point 6 feet ( 1 829mm) 
from the building. 

GRAIN (DIRECTION). The direction of the long axis of the 
dominant longitudinal cells or fibers in a log. 

GREEN (LOGS). Logs that have not undergone drying to a 
moisture content below the fiber saturation point. 

HEADER, LOG. The structural member that spans over the 
top of an opening. 

HIP BEAM, LOG. A beam spanning from the ridge to the out- 
side roof corner that supports the jack rafters or purlins, form- 
ing a sloping roof line. 

HOLD DOWN. A device used to provide overturning restraint 
by resisting uplift. 

JACK RAFTER, LOG. A rafter that spans from a hip or val- 
ley beam to a wall plate or ridge, respectively. 

KERF. A saw cut made along the length of a log. 

LOG. Wood member that has been stress graded and grade 
marked or grade certified using rules of an accredited inspec- 
tions agency in accordance with ASTM D 3957, ASTM D 
3737, or ASTM D 245 and is incorporated into a structure. 

LOG STRUCTURE. A type of construction whose primary 
structural elements are formed by a system of logs. 

LOG WALL. An assembly of individual structural logs for use 
as an exterior or interior load bearing wall, shear wall, or 
non-load bearing wall. 

MEAN ROOF HEIGHT. The distance from grade plane to 
the average roof elevation. 

MOISTURE CONTENT. The weight of water in the cell 
walls and cavities of wood, expressed as a percentage of 
oven-dry weight. 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



DEFINITIONS 



PURLIN, LOG. Horizontal roof beams, typically located 
between the top plate log and the ridge used to provide 
mid-span support for the roof superstructure and roofing dia- 
phragm. 

RAFTER, LOG. A structural member of a roof diaphragm 
that spans from the ridge to a purlin or eave. 

RAFTER OVERHANG (EAVE). The horizontal projection 
of a rafter measured from the outside face of the wall to the out- 
side edge of the rafter. 

RAFTER TIE, LOG. A structural framing member located in 
the lower half of the roof frame that connects the rafters 
together to resist outward thrust of the rafter log. 

RIDGE. The horizontal line formed by the joining of the top 
edges of two sloping roof surfaces. 

RIDGE BEAM, LOG. A structural horizontal log that sup- 
ports the roof diaphragm at the peak and transfers roof loads to 
supports. 

SETBACK. The offset distance of a wall on a floor system, 
measured from the support towards mid-span of the floor sys- 
tem. 

SETTLING. The reduction in height of a log wall due to any or 
all of the actions of compaction, shrinkage, or slumping of indi- 
vidual logs. 

SHEAR WALL. A vertical structural unit composed of one or 
more shear wall segments in one plane. 

SHEAR WALL SEGMENT. The vertical section of a shear 
wall without openings that forms a structural unit composed of 
framing members, and perimeter members which act as a deep, 
thin vertical cantilever beam designed to resist lateral forces 
parallel to the plane of the wall, and which meets the aspect 
ratio limits. 

SILL LOG. A horizontal log anchored to the foundation. 

SINGLE SPAN. The span made by a structural member 
between two supports. 

SLUMPING. The lateral spreading of the cope resulting in 
reduction of the log wall height. 

SPAN. The distance between face of supports, plus V 2 the 
required bearing length at each end. 

TOP PLATE, LOG. The top log in a wall, beam, outrigger, 
etc., that supports the lower end of the roofs diaphragm. 

VALLEY BEAM, LOG. A beam spanning from the ridge to 
an inside roof corner, that supports the jack rafters, forming a 
concave roof line. 

WINDOW SILL, LOG. A log in a wall immediately below a 
window opening. 



SECTION 203 
SYMBOLS 

A - Bearing area; cross-sectional area. 

B LP = Initial bearing area. 

B r = Required bearing area. 



E,E' 



F h , P\ 



F c \\, F'cW 



F c ±> F ci 



F* F\ 



F v , F\ = 



E' Modulus of elasticity, modulus of elasticity 
after all applicable adjustment factors have 
been applied. 

Allowable bending stress, allowable bending 
stress after all applicable adjustment factors 
have been applied. 

Allowable compressive stress parallel to 
grain, allowable compressive stress parallel to 
grain after all applicable adjustment factors 
have been applied. 

Allowable compressive stress perpendicular 
to grain, allowable compressive stress per- 
pendicular to grain after all applicable adjust- 
ment factors have been applied. 

Allowable tensile stress, allowable tensile 
stress after all applicable adjustment factors 
have been applied. 

Allowable parallel to grain shear stress, allow- 
able parallel to grain shear stress after all appli- 
cable adjustment factors have been applied. 



G 


- 


Specific gravity. 


H L 


= 


Log stack height. 


HC 


= 


Heat capacity. 


I 


- 


Moment of inertia. 


L 


= 


Floor diaphragm dimension perpendicular to 
the lateral load. 


M x 


= 


Allowable moment. 


MC 


= 


Moisture content as a percentage. 


MC D 


= 


Design moisture content. 


MC FSP 


= 


Moisture content at fiber saturation point. 


MC S 


= 


Service moisture content. 


P 


= 


Allowable compressive axial force. 


Q 


= 


Statical moment of an area about the neutral 
axis. 


s 


= 


Section modulus. 


s R 


- 


Radial shrinkage. 


S T 


= 


Tangential shrinkage. 



T = Allowable tensile axial force; diaphragm 

chord force. 

U = Coefficient of Transmission. 

b = Width of section. 

v = Required unit shear capacity of the floor or 

roof diaphragm. 

V r - Allowable beam shear. 

W L = Log thickness for calculation purposes. 

Ac = Settling due to compaction. 

As = Settling due to shrinkage. 

A SL - Settling due to slumping. 

At = Total settling. 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



CHAPTER 3 

GENERAL REQUIREMENTS 



SECTION 301 
GENERAL 

301.1 General. Log structures shall comply with the general 
requirements of this chapter. 



SECTION 302 
MATERIALS 

302.1 Materials. Materials used in the construction of log 
structures shall conform to the provisions of this Section. 
Materials used to conform to the applicable provisions of this 
standard shall be installed in accordance with the installation 
instructions provided for those materials. 

302.2 Logs. Log styles shall include, but are not limited to, 
round, rectangular or other shapes (profiles) that are peeled, 
notched, coped, hewn, sawn, milled, or otherwise profiled into 
their final form for installation. 

302.2.1 Stress grading. All logs shall be stress graded and 
identified by the grade mark or Certificate of Inspection 
issued by an accredited log grading agency. 

302.2.1.1 Log grades and design values. Log grades 
and design values shall be developed in accordance with 
one of the following standards: 

1, ASTMD3957 

2, ASTM D 3737 

3, ASTM D 245 

302.2.1.2 Species. Logs shall be of species that are listed 
with clear wood strength values as published in ASTM D 

2555. 

302.2.1.3 Grade marks. Grade marks or Certificates of 
Inspection shall include the following information: 

1 . Name or registered trade mark of the accredited 
grading agency. 

2. Name or identification number of the manufacturer. 

3. Species of logs. 

4. Grade name or designation. 

5. Moisture content at time of grading, if moisture 
content is other than green in conformance with 
Section 302.2.2.1. 

302.2.1.4 Log profile. The average log profile shall be 
drawn and dimensioned. 

302.2.2 Moisture content. Moisture content (MC) shall be 
evaluated in accordance with the requirements of this section. 

302.2.2.1 Design moisture content. The design mois- 
ture content {MC D ) shall be determined in accordance 
with the requirements of Section 302.2.2.1.1 or 
302.2.2.1.2. 



302.2.2.1.1 Prescriptive specification. Logs shall be 
evaluated as green and shall have design moisture 
content (MC D ) equal to the average moisture content 
at fiber saturation (MC fSP ), in accordance with Table 
304.2(1). 

302.2.2.1.2 Certified specification. The design 
moisture content shall be equal to the moisture con- 
tent determined and certified by methods prescribed 
by an accredited third-party grading agency. 

302.2.2.2 Service moisture content. The service mois- 
ture content (MC S ) shall be determined in accordance 
with the requirements of Section 302.2,2.2,1 or 

302.2.2.2.2. 

302.2.2.2.1 Prescriptive specification by climate 
zone. Prescribed by geographic climate zone using 
Figure 304.2.2.3 and Table 304.2(4). 

302.2.2.2.2 Calculation procedure. Calculated in 
accordance with ASTM D 4933. 

302.2.3 Design values. Elements of log structures shall 
have design values as prescribed in this section. 

302.2.3.1 Sawn lumber and glued laminated timber. 

Design values, adjustment factors and section properties 
for visually-graded and mechanically-graded dimension 
lumber and glued laminated timber shall be as specified 
in the AFPA NDS. 

302.2.3.2 Logs. Design values for softwood and hard- 
wood logs shall be as specified in Tables 302.2(1) 
through 302.2(5) or as established by an accredited grad- 
ing agency. Tabulated design values shall be multiplied 
by all applicable adjustment factors listed in Table 
302.2(6) to determine allowable design values. 

302.2.3.3 Specific gravity. The specific gravity (G) for 
wood species or species groups shall be obtained in accor- 
dance with one of the conditions listed in this section. 

302.2.3.3.1 Prescriptive specification for wood in 
unseasoned condition. Specific gravity shall be 
obtained from ASTM D 2555. 

302.2.3.3.2 Prescriptive specification for wood in 
oven-dry condition. Specific gravity shall be taken 
from AF&PA NDS. 

302.2.3.3.3 Calculation procedure. Specific gravity 
shall be calculated by the equation G = Gu / 
[l-(0.265aGu)] 

where: 

Gu = specific gravity based on unseasoned 
condition (ASTM D 2555). 

a ^ {MC FSP -MC S )IMC FSP . 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



TABLE 302.2(1) 
LIST OF SPECIES COMBINATIONS 



Species or Species 
Combination 13 


Species Permitted To Be 
Included in Combination 


Source Agencies 3 


Design Values Provided in 
Tables 


Appalachian Softwoods 


Fir: Balsam 

Fir: Balsam - Canadian 

Hemlock: Eastern 

Hemlock: Eastern - Canadian 

Pine: Eastern White 

Pine: Eastern White - Canadian 

Pine: Jack 

Pine: Jack - Canadian 

Pine: Red 

Pine: Red - Canadian 

Southern Pine: Loblolly 

Southern Pine: Longleaf 

Southern Pine: Shortleaf 

Southern Pine: Slash 

Pine: Pitch 

Pine: Pond 

Pine: Sand 

Pine: Spruce 

Pine: Virginia 

Spruce: Black - Canadian 

Spruce: Red 
Spruce: Red - Canadian 

Spruce: White 

Spruce: White - Canadian 

Tamarack 

Tamarack - Canadian 


TP 


SRTB, Wall-Log 


Aspen 


Aspen: Bigtooth 

Aspen: 

Largetooth-Canadian 

Aspen: Quaking 

Aspen: Trembling-Canadian 


LHC, TP 


SRTB, Wall-Log 


Bald Cypress 




TP 


SRTB, Wall-Log 


Beech 




TP 


SRTB 


Cedar: Incense (IC) 




LHC, TP 


SRTB, Wall-Log 


Cedar: Northern White 




TP 


SRTB, Wall-Log 


Cedar, Red (Western, RC) 


Cedar: Incense (IC) 

Cedar: Western red (WRC) 

Cedar: Western 

red-Canadian (WRC-N) 


LHC 


SRTB, Wall-Log 


Cedar: Western red (WRC) 




LHC, TP 


SRTB, Wall-Log 


Cedar: Western red-Canadian 
(WRC-N) 




LHC 


SRTB, Wall-Log 


Cedar: White (WC) 


Cedar: Atlantic white 
Cedar: Eastern 
white-Canadian 

Cedar: Northern white 


LHC 


Wall-Log 


Douglas Fir 


— 


TP 


SRTB, Wall-Log 


Douglas Fir - N 


— 


TP 


SRTB, Wall-Log 


Douglas Fir - S 


— 


TP 


SRTB, Wall-Log 


Douglas Fir-Larch (DFL) 


Douglas fir: Interior West 

Douglas fir-Canadian 

Douglas fir: Coast 

Douglas fir: Interior North 

Douglas fir: Interior South 

Larch, western 
Larch, western-Canadian 


LHC, TP 


SRTB, Wall-Log 



(continued) 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



TABLE 302.2(1)— continued 
LIST OF SPECIES COMBINATIONS 



Species or Species 
Combination 


Species Permitted To Be 

Included in 

Combination 


Grading 

Rules 
Agencies 


Design Values 
Provided in Tables 


Eastern Spruce-Pine-Fir (ESPF) 


Fir: Balsam 
Fir: Balsam-Canadian 

Pine: Jack 

Pine: Jack-Canadian 

Pine: Red (RP) 

Pine: Red-Canadian (RP-N) 

Spruce: Black 

Spruce: Black-Canadian 

Spruce: Red 
Spruce: Red-Canadian 

Spruce: White 
Spruce: White-Canadian 


LHC 


SRTB, Wall-Log 


Eastern Softwoods (ESW) 


Fir: Balsam 

Fir: Balsam-Canadian 

Hemlock: Eastern 

Hemlock: Eastern-Canadian 

Pine: Eastern white (EWP) 

Pine: Eastern white-Canadian 

Pine: Jack 

Pine: Jack-Canadian 

Pine: Pitch 

Pine: Red (RP) 

Pine: Red-Canadian (RP-N) 

Spruce: Black 

Spruce: Black-Canadian 

Spruce: Red 
Spruce: Red-Canadian 

Spruce: White 

Spruce: White-Canadian 

Tamarack (TAM) 

Tamarack-Canadian 


LHC, TP 


SRTB, Wall-Log 


Eastern Woods 




TP 


SRTB, Wall -Log 


Fir: Alpine 




TP 


SRTB, Wall-Log 


Fir: Balsam 




TP 


SRTB, Wall-Log 


Fir: White WF) 




LHC 


Wall-Log 


Hem-Fir (HF) 


Fir: Amabilis-Canadian 

Fir: California red 

Fir: Grand 

Fir: Noble 

Fir: Pacific silver 

Fir: White (WF) 

Hemlock: Western 

Hemlock: Western-Canadian 


LHC, TP 


SRTB, Wall-Log 


Hemlock: Eastern 




TP 


SRTB 


Eastern Hemlock - Tamarack 




TP 


SRTB, Wall-Log 


Hemlock: Western 




TP 


SRTB, Wall-Log 


Larch: Western 




TP 


SRTB, Wall-Log 


Mixed Oak 




TP 


SRTB, Wall-Log 


Mixed Southern Pine (MSP) 


Pine: Loblolly (LBP) 
Pine: Longleaf (LLP) 

Pine: Slash (SHP) 

Pine: Shortleaf (SLP) 

Pine: Pond 

Pine: Sand 

Pine: Spruce 

Pine: Virginia 


LHC, TP 


SRTB, Wall-Log 



(continued) 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



TABLE 302.2(1) —continued 
LIST OF SPECIES COMBINATIONS 



Species or Species 
Combination 


Species Permitted To Be 

Included in 

Combination 


Grading 

Rules 
Agencies 


Design Values 
Provided in Tables 


Oak, Red (RO) 


Oak, Black 

Oak, Cherrybark 

Oak, Northern red 

Oak, Southern red 

Oak, Laurel 

Oak, Pin 
Oak, Scarlet 
Oak, Water 
Oak, Willow 


LHC, TP 


SRTB, Wall-Log 


Oak, White (WO) 


Oak, Chestnut 

Oak, Live 

Oak, Post 

Oak, Swamp chestnut 

Oak, White 

Oak, Bur 

Oak, Overcup 

Oak, Swamp white 


LHC, TP 


SRTB, Wall-Log 


Pine: Eastern white (EWP) 




LHC, TP 


SRTB, Wall-Log 


Pine: Idaho White 




TP 


SRTB, Wall-Log 


Pine: Loblolly (LBP) 




LHC 


SRTB, Wall-Log 


Pine: Lodgepole (LPP) 




LHC, TP 


SRTB, Wall-Log 


Pine: Longleaf (LLP) 




LHC 


SRTB, Wall-Log 


Pine: Northern 




TP 


SRTB, Wall-Log 


Pine: Ponderosa (PP) 




LHC, TP 


SRTB, Wall-Log 


PP-LP 


Pine: Ponderosa (PP) 
Pine: Lodgepole (LPP) 


TP 


SRTB, Wall-Log 


PP-SP 


Pine: Ponderosa (PP) 
Pine: Sugar (SP) 


TP 


SRTB, Wall-Log 


Pine: Red (RP) 




LHC 


SRTB, Wall-Log 


Pine: Red-Canadian (RP-N) 




LHC 


SRTB, Wall-Log 


Pine: Shortleaf (SLP) 




LHC 


SRTB 


Pine: Slash (SHP) 




LHC 


SRTB 


Pine: Sugar (SUP) 




LHC, TP 


SRTB, Wall-Log 


Pine: Western white (WWP) 




LHC 


SRTB, Wall-Log 


Redwood 




TP 


SRTB, Wall-Log 


Southern Pine (SP) 


Pine: Loblolly (LBP) 
Pine: Longleaf (LLP) 

Pine: Slash (SHP) 
Pine: Shortleaf (SLP) 


LHC, TP 


SRTB, Wall-Log 


Spruce: Eastern (ES) 


Spruce: Black 
Spruce: Black-Canadian 

Spruce: Red 
Spruce: Red-Canadian 

Spruce: White 
Spruce: White-Canadian 


LHC, TP 


SRTB, Wall-Log 


Spruce: Engelmann 




TP 


SRTB, Wall-Log 


ES-AF 


Spruce: Engelmann 
Alpine Fir 


TP 


SRTB, Wall-Log 


ES-LP 


Spruce: Engelmann 
Pine: Lodgepole 


TP 


SRTB, Wall-Log 



(continued) 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



TABLE 302.2(1) —continued 
LIST OF SPECIES COMBINATIONS 



Species or Species 
Combination 


Species Permitted To Be 

Included in 

Combination 


Grading 

Rules 

Agencies 


Design Values 
Provided in Tables 


ES-AF-LP 


Spruce: Engelmann 

Alpine Fir 
Pine: Lodgepole 


TP 


SRTB, Wall-Log 


Spruce-Pine-Fir 




TP 


SRTB, Wall-Log 


Tamarack (TAM) 




LHC, TP 


SRTB, Wall-Log 


Western Spruce-Pine-Fir (WSPF) 


Fir: Alpine-Canadian 

Pine: Lodgepole (LPP) 

Pine: Lodgepole-Canadian 

(LPP-N) 

Spruce: Engelmann 

Spruce: Engelmann-Canadian 

Spruce: Sitka 

Spruce: Sitka-Canadian 


LHC 


SRTB, Wall-Log 


Western Softwoods (WS) 


Fir: Subalpine 

Hemlock: Mountain 

Pine: Lodgepole (LPP) 

Pine: Lodgepole-Canadian 

(LPP-N) 

Pine: Monterey 

Pine: Ponderosa (PP) 

Pine: Ponderosa-Canadian 

Pine: Sugar (SUP) 

Pine: Western white (WWP) 

Pine: Western white-Canadian 

Spruce: Engelmann 

Spruce: Engelmann-Canadian 

Spruce: Sitka 


LHC 


SRTB, Wall-Log 


Western Woods 




TP 


SRTB, Wall-Log 


White Woods 




TP 


SRTB, Wall-Log 



a. Source agencies: 

1. LHC: Log Home Council, National Association of Home Builders 

2. TP: Timber Products Inspection, Inc. 

b. Species combinations listed represent typical combinations utilized by TP or LHC member clients. Other species combinations published by accredited grading 
agencies are permissible. The grading agencies listed here do not preclude the use of other accredited grading agencies. 

c. Identified species and their subsequent design values were obtained from clear wood test data as shown within ASTM D 2555. 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 





TABLE 302.2(2) 
SECTION PROPERTIES OF SAWN AND UNSAWN ROUND TIMBER BEAMS 




Nominal 
Diameter (inches) 


Sawn Round Timber Beams 3 


Unsawn (Full Round) Timber Beams 


Area of 
Section (in 2 ) 


(x-x axis) 


Area of Section (in 2 ) 


Section Modulus 
(in 3 ) 


Moment of Inertia 
(in 4 ) 


Section Modulus 
(in 3 ) 


Moment of Inertia 
(in 4 ) 


2.8461 
*radius 2 


0.6159 
*radius 3 


0.5612 'radius 4 


3.1416 
*radius 2 


0.7854 
*radius 3 


0.7854 *radius 4 


5 


17.79 


9.62 


21.92 


19.63 


12.27 


30.68 


5.5 


21.52 


12.81 


32.09 


23.76 


16.33 


44.92 


6 


25.61 


16.63 


45.45 


28.27 


21.21 


63.62 


6.5 


30.06 


21.14 


62.61 


33.18 


26.96 


87.62 


7 


34.86 


26.41 


84.21 


38.48 


33.67 


117.86 


7.5 


40.02 


32.48 


110.97 


44.18 


41.42 


155.32 


8 


45.54 


39.42 


143.66 


50.27 


50.27 


201.06 


8.5 


51.41 


47.28 


183.08 


56.75 


60.29 


256.24 


9 


57.63 


56.13 


230.11 


63.62 


71.57 


322.06 


9.5 


64.21 


66.01 


285.67 


70.88 


84.17 


399.82 


10 


71.15 


76.99 


350.72 


78.54 


98.17 


490.87 


10.5 


78.45 


89.13 


426.31 


86.59 


113.65 


596.66 


11 


86.09 


102.47 


513.49 


95.03 


130.67 


718.69 


11.5 


94.1 


117.09 


613.42 


103.87 


149.31 


858.54 


12 


102.46 


133.04 


727.26 


113.1 


169.65 


1017.88 


14 


139.46 


211.26 


1347.34 


153.94 


269.39 


1885.74 


15 


160.09 


259.84 


1775.54 


176.71 


331.34 


2485.05 


16 


182.15 


315.35 


2298.5 


201.06 


402.12 


3216.99 


18 


230.53 


449 


3681.75 


254.47 


572.56 


5153 


20 


284.61 


615.92 


5611.57 


314.16 


785.4 


7853.98 


24 


409.84 


1064.31 


11636.16 


452.39 


1357.17 


16286.02 



For SI: 1. inch = 25.4 mm. 

Note; Maximum allowable taper is 7 8 inch per 12 inches (3.175 mm per 305 mm) from tip to 36 inches (914 mm) from butt. 

a. Sawn round timber beams are sawn or shaved along only one surface such that the sawing or shaving does not exceed 3 / 10 of the radius of the log at any point. 



10 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



TABLE 302.2(3) 
BASE DESIGN VALUES FOR SAWN ROUND AND UNSAWN ROUND TIMBER BEAMS 

These values are for timbers that are either completely round or that are sawn or shaved along only one surface such that the sawing 
or shaving does not exceed 3 / )0 of the radius of the log at any point. 



Species and 

commercial 

grade d 


_ b,e,f,g,h 
Design values in pounds per square inch (lbf/in z ) 


Source 
Agency 3 


Bending 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

9 rain F c± 


Compression 
parallel to grain 

^dl 


Modulus of 
Elasticity E*10 6 


Appalachian Softwoods 


Unsawn 


1350 


750 


125 


350 


725 


1.1 


TP 


No. 1 


1100 


600 


125 


350 


600 


1.1 


No. 2 


925 


500 


125 


350 


500 


1.1 


No. 3 


525 


300 


125 


350 


275 


0.8 


Aspen 


Unsawn 


1400 


775 


115 


245 


650 


0.9 


TP 


No. 1 


1150 


625 


115 


245 


525 


0.9 


No. 2 


975 


525 


115 


245 


425 


0.9 


No. 3 


550 


300 


115 


245 


250 


0.7 


Bald Cypress (CYP) G=0.43 unseasoned condition 


Unsawn 


1850 


1000 


150 


615 


1050 


1.3 


TP 


No. 1 


1500 


825 


150 


615 


875 


1.3 


No. 2 


1250 


675 


150 


615 


725 


1.3 


No. 3 


725 


400 


150 


615 


425 


1 


Beech 


Unsawn 


2350 


1300 


230 


815 


1050 


1.5 


TP 


No. 1 


1950 


1050 


230 


815 


875 


1.5 


No. 2 


1600 


875 


230 


815 


725 


1.5 


No. 3 


925 


500 


230 


815 


425 


1.2 


Cedar Insence (IC) G=0.35 unseasoned condition 


No. 1 


1400 


775 


160 


630 


925 


0.9 


LHC 


No. 2 


1150 


650 


160 


630 


775 


0.9 


No. 1 unsawn 


1650 


900 


160 


630 


925 


0.9 


Unsawn 


1700 


950 


150 


565 


950 


0.9 


TP 


No. 1 


1400 


775 


150 


565 


775 


0.9 


No. 2 


1150 


650 


150 


565 


650 


0.9 


No. 3 


675 


375 


150 


565 


375 


0.7 



(continued) 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



11 



GENERAL REQUIREMENTS 





TABLE 302.2(3)— continued 
BASE DESIGN VALUES FOR SAWN ROUND AND UNSAWN ROUND TIMBER BEAMS 




Species and 

commercial 

grade d 


9 b,e 

Design values in pounds per square inch (Ibf/in ) 


Source Agency 3 


Bending 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cl 


Compression 
parallel to grain 

^dl 


Modulus of 
Elasticity E*10 6 


Cedar (North White) 


Unsawn 


1150 


650 


110 


370 


600 


0.7 


TP 


No. 1 


950 


525 


110 


370 


475 


0.7 


No. 2 


800 


450 


110 


370 


400 


0.7 


No. 3 


450 


250 


110 


370 


225 


0.5 


Cedar, Red (Western, RC) G=0.31 unseasoned condition 


No. 1 


1250 


675 


140 


490 


825 


1.0 


LHC 


No. 2 


1000 


550 


140 


490 


700 


1.0 


No. 1 unsawn 


1450 


775 


140 


490 


825 


1.0 


Cedar: Western red (WRC) G=0.31 unseasoned condition 


No. 1 


1200 


650 


145 


430 


825 


1.0 


LHC 


No. 2 


1000 


550 


145 


430 


700 


1.0 


No. 1 unsawn 


1400 


775 


145 


430 


825 


1.0 


Unsawn 


1500 


800 


135 


385 


825 


1 


TP 


No. 1 


1200 


650 


135 


385 


675 


1 


No. 2 


1000 


550 


135 


385 


575 


1 


No. 3 


575 


325 


135 


385 


325 


0.8 


Cedar: Western red-Canadian (WRC-N) G=0.31 unseasoned condition 


No. 1 


1200 


650 


135 


485 


825 


1.1 


LHC 


No. 2 


1000 


550 


135 


485 


700 


1.1 


No. 1 unsawn 


1400 


775 


135 


485 


825 


1.1 


Douglas fir 


Unsawn 


2050 


1150 


160 


630 


1100 


1.6 


LHC 


No. 1 


1700 


925 


160 


630 


900 


1.6 


No. 2 


1400 


775 


160 


630 


750 


1.6 


No. 3 


800 


450 


160 


630 


425 


1.3 


Douglas Fir- N 


Unsawn 


2050 


1150 


175 


600 


1050 


1.5 


TP 


No. 1 


1700 


925 


175 


600 


850 


1.5 


No. 2 


1400 


775 


175 


600 


725 


1.5 


No. 3 


800 


450 


175 


600 


400 


1.2 


Douglas Fir-S 


Unsawn 


2000 


1100 


170 


520 


975 


1.2 


T 


No. 1 


1600 


900 


170 


520 


800 


1.2 


P 


No. 2 


1350 


750 


170 


520 


675 


1.2 


No. 3 


775 


425 


170 


520 


375 


1 



(continued) 



12 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 





TABLE 302.2(3)— continued 
BASE DESIGN VALUES FOR SAWN ROUND AND UNSAWN ROUND TIMBER BEAMS 




Species and 

commercial 

grade d 


b,e 

Design values in pounds per square inch (lbf/in^) 


Source Agency 3 


Bending 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cl 


Compression 
parallel to grain 

Pdl 


Modulus of 
Elasticity E*10 6 


Douglas Fir-Larch (DFL) G=0.45 unseasoned condition 


No. 1 Dense 


2000 


1100 


175 


805 


1250 


1.5 


LHC 


No. 1 


1700 


925 


175 


710 


1100 


1.4 


No. 2 Dense 


1650 


925 


175 


805 


1050 


1.5 


No. 2 


1400 


775 


175 


710 


900 


1.4 


No. 1 Dense unsawn 


2350 


1300 


175 


805 


1250 


1.5 


No. 1 unsawn 


2000 


1100 


175 


710 


1100 


1.4 


Unsawn 


2050 


1150 


175 


600 


1050 


1.5 


TP 


No. 1 


1700 


925 


175 


600 


850 


1.5 


No. 2 


1400 


775 


175 


600 


725 


1.5 


No. 3 


800 


450 


175 


600 


400 


1.2 


E. Spruce-Pine-Fir (ESPF) G=0.38 unseasoned condition 


No. 1 


1150 


625 


135 


480 


725 


1.2 


LHC 


No. 2 


950 


525 


135 


480 


600 


1.2 


No. 1 unsawn 


1350 


725 


135 


480 


725 


1.2 


Eastern Softwoods (ESW) G=0.38 unseasoned condition 


No. 1 


1150 


625 


125 


480 


725 


1.2 


LHC 


No. 2 


950 


525 


125 


480 


600 


1.2 


No. 1 unsawn 


1350 


725 


125 


480 


725 


1.2 


Unsawn 


1350 


750 


125 


350 


725 


1.1 


TP 


No. 1 


1100 


600 


125 


350 


600 


1.1 


No. 2 


925 


500 


125 


350 


500 


1.1 


No. 3 


525 


300 


125 


350 


275 


0.8 


Eastern Woods 


Unsawn 


1350 


750 


125 


350 


725 


1.1 


TP 


No. 1 


1100 


600 


125 


350 


600 


1.1 


No. 2 


925 


500 


125 


350 


500 


1.1 


No. 3 


525 


300 


125 


350 


275 


0.8 


Fir: Alpine 


Unsawn 


1450 


775 


125 


405 


750 


1.3 


TP 


No. 1 


1150 


650 


125 


405 


600 


1.3 


No. 2 


975 


525 


125 


405 


500 


1.3 


No. 3 


550 


300 


125 


405 


300 


1.1 



(continued) 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



13 



GENERAL REQUIREMENTS 





TABLE 302.2(3)— continued 
BASE DESIGN VALUES FOR SAWN ROUND AND UNSAWN ROUND TIMBER BEAMS 




Species and 

commercial 

grade d 


b,e 

Design values in pounds per square inch (Ibf/in^) 


Source Agency 3 


Bending 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cl 


Compression 
parallel to grain 

*yi 


Modulus of 
Elasticity E*10 6 


Fir: Balsam 


Unsawn 


1750 


950 


125 


305 


925 


1.3 


TP 


No. 1 


1400 


775 


125 


305 


750 


1.3 


No. 2 


1200 


650 


125 


305 


625 


1.3 


No. 3 


675 


375 


125 


305 


350 


1.1 


Hem-Fir (HF) G=0.39 unseasoned condition 


No. 1 


1300 


700 


140 


535 


850 


1.4 


LHC 


No. 2 


1050 


600 


140 


535 


725 


1.4 


No. 1 unsawn 


1500 


825 


140 


535 


850 


1.4 


Unsawn 


1650 


900 


135 


370 


850 


1.2 


TP 


No. 1 


1350 


725 


135 


370 


700 


1.2 


No. 2 


1100 


600 


135 


370 


575 


1.2 


No. 3 


625 


350 


135 


370 


325 


1 


Hemlock: Eastern 


Unsawn 


1800 


975 


155 


550 


925 


1.1 


TP 


No. 1 


1450 


800 


155 


550 


750 


1.1 


No. 2 


1200 


675 


155 


550 


625 


1.1 


No. 3 


700 


375 


155 


550 


350 


0.9 


Eastern Hemlock -Tamarack 


Unsawn 


1800 


975 


155 


550 


925 


1.1 


TP 


No. 1 


1450 


800 


155 


550 


750 


1.1 


No. 2 


1200 


675 


155 


550 


625 


1.1 


No. 3 


700 


375 


155 


550 


350 


0.9 


Hemlock: Western 


Unsawn 


1800 


1000 


160 


410 


1000 


1.4 


TP 


No. 1 


1500 


825 


160 


410 


825 


1.4 


No. 2 


1250 


675 


160 


410 


675 


1.4 


No. 3 


700 


400 


160 


410 


400 


1.1 


Larch: Western 


Unsawn 


2250 


1250 


175 


605 


1200 


1.6 


TP 


No. 1 


1850 


1000 


175 


605 


975 


1.6 


No. 2 


1550 


850 


175 


605 


825 


1.6 


No. 3 


875 


475 


175 


605 


475 


1.2 





(continued) 



14 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 





TABLE 302.2(3)— continued 
BASE DESIGN VALUES FOR SAWN ROUND AND UNSAWN ROUND TIMBER BEAMS 




Species and 

commercial 

grade d 


o b,e 

Design values in pounds per square inch (Ibf/in^) 


Source Agency 3 


Bending 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cl 


Compression 
parallel to grain 

^dl 


Modulus of 
Elasticity E*10 6 


Mixed Oak 


Unsawn 


1900 


1050 


170 


820 


900 


1.2 


TP 


No. 1 


1550 


850 


170 


820 


750 


1.2 


No. 2 


1300 


725 


170 


820 


625 


1.2 


No. 3 


750 


400 


170 


820 


350 


1 


Mixed Southern Pine (MSP) G=0.48 unseasoned condition 


No. 1 Dense 


1550 


850 


175 


755 


975 


1.2 


LHC 


No. 1 


1350 


725 


175 


670 


825 


1.2 


No. 2 Dense 


1300 


725 


175 


755 


825 


1.2 


No. 2 


1100 


625 


175 


670 


700 


1.2 


No. 1 Dense 
unsawn 


1850 


1000 


175 


755 


975 


1.2 


No. 1 unsawn 


1600 


875 


175 


670 


825 


1.2 


Unsawn 


2050 


1100 


160 


595 


1000 


1.3 


TP 


No. 1 


1650 


900 


160 


595 


825 


1.3 


No. 2 


1400 


750 


160 


595 


700 


1.3 


No. 3 


800 


425 


160 


595 


400 


1 


Oak, Red (RO) G=0.57 unseasoned condition 


No. 1 


1500 


800 


160 


985 


850 


1.3 


LHC 


No. 2 


1250 


675 


160 


985 


700 


1.3 


No. 1 unsawn 


1750 


950 


160 


985 


850 


1.3 


Unsawn 


1900 


1050 


170 


820 


900 


1.2 


TP 


No. 1 


1550 


850 


170 


820 


750 


1.2 


No. 2 


1300 


725 


170 


820 


625 


1.2 


No. 3 


750 


400 


170 


820 


350 


1 


Oak, White (WO) G=0.62 unseasoned condition 


No. 1 


1550 


850 


210 


1225 


925 


1 


LHC 


No. 2 


1300 


700 


210 


1225 


775 


1 


No. 1 unsawn 


1800 


1000 


210 


1225 


925 


1 


Unsawn 


2000 


1100 


220 


795 


975 


0.9 


TP 


No. 1 


1600 


900 


220 


795 


800 


0.9 


No. 2 


1350 


750 


220 


795 


675 


0.9 


No. 3 


775 


425 


220 


795 


375 


0.7 



(continued) 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



15 



GENERAL REQUIREMENTS 





TABLE 302.2(3)— continued 
BASE DESIGN VALUES FOR SAWN ROUND AND UNSAWN ROUND TIMBER BEAMS 




Species and 

commercial 

grade d 


Design values in pounds per square inch (Ibf/in^) 


Source Agency 3 


Bending 
Ft 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cl 


Compression 
parallel to grain 


Modulus of 
Elasticity E*10 6 


Pine: Eastern White (EWP) G=0.35 unseasoned condition 


No. 1 


1100 


600 


130 


390 


725 


1.1 


LHC 


No. 2 


925 


500 


130 


390 


600 


1.1 


No. 1 unsawn 


1300 


725 


130 


390 


725 


1.1 


Unsawn 


1350 


750 


125 


350 


725 


1.1 


TP 


No. 1 


1100 


600 


125 


350 


600 


1.1 


No. 2 


925 


500 


125 


350 


500 


1.1 


No. 3 


525 


300 


125 


350 


275 


0.8 


Pine: Idaho White 


Unsawn 


1350 


725 


125 


310 


750 


1.3 


TP 


No. 1 


1100 


600 


125 


310 


600 


1.3 


No. 2 


900 


500 


125 


310 


500 


1.3 


No. 3 


525 


275 


125 


310 


300 


1 


Pine: Loblolly (LBP) G=0.35 unseasoned condition 


No. 1 


1650 


900 


170 


660 


1050 


1.5 


LHC 


No. 2 


1350 


750 


170 


660 


875 


1.5 


No. 1 unsawn 


1900 


1050 


170 


660 


1050 


1.5 


Pine: Lodgepole (LPP) G=0.39 unseasoned condition 


No. 1 


1250 


675 


130 


445 


775 


1.1 


LHC 


No. 2 


1050 


575 


130 


445 


650 


1.1 


No. 1 unsawn 


1450 


800 


130 


445 


775 


1.1 


Unsawn 


500 


825 


125 


395 


775 


1.1 


TP 


No. 1 


1250 


675 


125 


395 


625 


1.1 


No. 2 


1050 


575 


125 


395 


525 


1.1 


No. 3 


600 


325 


125 


395 


300 


0.9 


Pine: Longleaf (LLP) G=0.54 unseasoned condition 


No. 1 


1950 


1100 


210 


805 


1350 


1.7 


LH 


No. 2 


1650 


900 


210 


805 


1100 


1.7 


No. 1 unsawn 


2300 


1250 


210 


805 


1350 


1.7 


Pine: Northern 


Unsawn 


1600 


875 


125 


405 


825 


1.1 


TP 


No. 1 


1300 


725 


125 


405 


675 


1.1 


No. 2 


1100 


600 


125 


405 


550 


1.1 


No. 3 


625 


350 


125 


405 


325 


0.9 



(continued) 



16 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 





TABLE 302.2(3)— continued 
BASE DESIGN VALUES FOR SAWN ROUND AND UNSAWN ROUND TIMBER BEAMS 




Species and 

commercial 

grade d 


b,e 

Design values in pounds per square inch (Ibf/in ) 


Source Agency 3 


Bending 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cl 


Compression 
parallel to grain 

^dl 


Modulus of 
Elasticity E*10 6 


Pine: Ponderosa (PP) G=0.39 unseasoned condition 


No. 1 


1150 


625 


135 


490 


725 


1.1 


LHC 


No. 2 


975 


525 


135 


490 


600 


1.1 


No. 1 unsawn 


1350 


750 


135 


490 


725 


1.1 


Unsawn 


1400 


775 


130 


440 


725 


1.1 


TP 


No, 1 


1150 


625 


130 


440 


600 


1.1 


No. 2 


975 


525 


130 


440 


500 


1.1 


No. 3 


550 


300 


130 


440 


275 


0.8 


Ponderosa Pine -Lodgepole Pine (PP-LP) 


Unsawn 


1400 


775 


125 


395 


725 


1.1 


T p 


No. 1 


1150 


625 


125 


395 


600 


1.1 


No. 2 


975 


525 


125 


395 


500 


1.1 


No. 3 


550 


300 


125 


395 


275 


0.8 


Ponderosa Pine - Sugar Pine (PP-SP) 


Unsawn 


1450 


775 


130 


345 


725 


1.1 


TP 


No. 1 


1150 


650 


130 


345 


600 


1.1 


No. 2 


975 


525 


130 


345 


500 


LI 


No. 3 


550 


300 


130 


345 


275 


0.8 


Pine: Red (RP) 


No. 1 


1300 


725 


130 


455 


800 


1.4 


LHC 


No. 2 


1100 


600 


130 


455 


675 


1.4 


No. 1 unsawn 


1550 


850 


130 


455 


800 


1.4 


Pine: Red-Canadian (RP-N) G=0.39 unseasoned condition 


No. 1 


1150 


625 


135 


490 


700 


1.1 




No. 2 


950 


525 


135 


490 


600 


1.1 


No. 1 unsawn 


1350 


725 


135 


490 


700 


1.1 


Pine: : Shortieaf (SLP) 


LHC 


No. 1 


1700 


925 


175 


575 


1100 


1.5 




No. 2 


1400 


775 


175 


575 


925 


1.5 


No. 1 unsawn 


2000 


1100 


175 


575 


1100 


1.5 


Pine: Slash (SHP) 


No. 1 


2100 


1150 


190 


885 


1250 


l.fi 


LHC 


No. 2 


1750 


950 


190 


885 


1050 


1.6 


No. 1 unsawn 


2450 


1350 


190 


885 


1250 


1.6 



(continued) 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



17 



GENERAL REQUIREMENTS 





TABLE 302.2(3)~continued 
BASE DESIGN VALUES FOR SAWN ROUND AND UNSAWN ROUND TIMBER BEAMS 




Species and 

commercial 

grade d 


5 b,e 

Design values in pounds per square inch (lbf/in^) 


Source Agency 3 


Bending 
Ft 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cl 


Compression 
parallel to grain 

F 4\ 


Modulus of 
Elasticity E*10 6 


Pine: Sugar (SUP) G=0.34 unseasoned condition 


No. 1 


1150 


650 


135 


380 


115 


1.1 


LHC 


No. 2 


975 


525 


135 


380 


650 


1.1 


No. 1 unsawn 


1350 


750 


135 


380 


775 


1.1 


Unsawn 


1450 


775 


130 


345 


775 


1.1 


TP 


No. 1 


1150 


650 


130 


345 


625 


1.1 


No. 2 


975 


525 


130 


345 


525 


1.1 


No. 3 


550 


300 


130 


345 


300 


0.9 


Pine: Western White (WWP) G=0.35 unseasoned condition 


No. 1 


1100 


600 


130 


350 


750 


1.3 


LHC 


No. 2 


900 


500 


130 


350 


625 


1.3 


No. 1 unsawn 


1300 


700 


130 


350 


750 


1.3 


Redwood 


Unsawn 


1650 


900 


150 


420 


925 


1 


TP 


No. 1 


1350 


725 


150 


420 


750 


1 


No. 2 


1100 


600 


150 


420 


625 


1 


No. 3 


650 


350 


150 


420 


375 


0.8 


Southern Pine (SP) G=0.48 unseasoned condition 


No. 1 Dense 


2000 


1100 


175 


755 


1300 


1.6 


LHC 


No. 1 


1700 


950 


175 


670 


1100 


1.5 


No. 2 Dense 


1700 


925 


175 


755 


1100 


1.6 


No. 2 


1450 


800 


175 


670 


925 


1.5 


No. 1 Dense 
unsawn 


2400 


1300 


175 


755 


1300 


1.6 


No. 1 unsawn 


2050 


1100 


175 


670 


1100 


1.5 


Unsawn 


2000 


1100 


160 


515 


1050 


1.5 


TP 


No. 1 


1650 


900 


160 


515 


875 


1.5 


No. 2 


1350 


750 


160 


515 


725 


1.5 


No. 3 


775 


425 


160 


515 


425 


1.2 



(continued) 



18 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 





TABLE 302.2(3)— continued 
BASE DESIGN VALUES FOR SAWN ROUND AND UNSAWN ROUND TIMBER BEAMS 




Species and 

commercial 

grade d 


Design values in pounds per square inch (Ibf/in ) 


Source Agency 3 


Bending 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cl 


Compression 
parallel to grain 

_ Ii\ 


Modulus of 
Elasticity E*10 6 


Spruce: Eastern (ES) G=0.38 unseasoned condition 


No. 1 


1150 


625 


135 


480 


725 


1.3 


LHC 


No. 2 


950 


525 


135 


480 


600 


1.3 


No. 1 unsawn 


1350 


725 


135 


480 


725 


1.3 


Unsawn 


1400 


775 


125 


390 


750 


1.2 


TP 


No. 1 


1150 


625 


125 


390 


600 


1.2 


No. 2 


950 


525 


125 


390 


500 


1.2 


No. 3 


550 


300 


125 


390 


300 


1 


Spruce: Engelmann G=0.33 unseasoned condition 


Unsawn 


1350 


725 


125 


320 


625 


1.1 


TP 


No. 1 


1100 


600 


125 


320 


500 


1.1 


No. 2 


900 


500 


125 


320 


425 


t.l 


No. 3 


525 


275 


125 


320 


250 


0.9 


Engelmann Spruce — Alpine Fir (ES-AF) 


Unsawn 


1350 


725 


125 


320 


625 


1.1 


TP 


No. 1 


1100 


600 


125 


320 


500 


1.1 


No. 2 


900 


500 


125 


320 


425 


1.1 


No. 3 


525 


275 


125 


320 


250 


0.9 


Engelmann Spruce - Lodgepole Pine (ES-LP) 


Unsawn 


1350 


725 


125 


320 


625 


1.1 


TP 


No. 1 


1100 


600 


125 


320 


500 


1.1 


No. 2 


900 


500 


125 


320 


425 


1.1 


No. 3 


525 


275 


125 


320 


250 


0.9 


Engelmann Spruce - Alpine Fir - Lodgepole Pine (ES-AF-LP) 


Unsawn 


1350 


725 


125 


320 


625 


1.1 


TP 


No. 1 


1100 


600 


125 


320 


500 


1.1 


No. 2 


900 


500 


125 


320 


425 


1.1 


No. 3 


525 


275 


125 


320 


250 


0.9 


Spruce-Pine-Fir 


Unsawn 


1350 


725 


125 


305 


625 


1.1 


TP 


No. 1 


1100 


600 


125 


305 


500 


1.1 


No. 2 


900 


500 


125 


305 


425 


1.1 


No. 3 


525 


275 


125 


305 


250 


0.9 



(continued) 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



19 



GENERAL REQUIREMENTS 





TABLE 302.2(3)— continued 
BASE DESIGN VALUES FOR SAWN ROUND AND UNSAWN ROUND TIMBER BEAMS 




Species and 

commercial 

grade d 


9 b,e 

Design values in pounds per square inch (lbf/in^) 


Source Agency 3 


Bending 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cl 


Compression 
parallel to grain c 


Modulus of 
Elasticity E*10 6 


Tamarack (TAM) 


No. 1 


1600 


900 


165 


660 


1050 


1.3 


LHC 


No. 2 


1350 


750 


165 


660 


875 


1.3 


No. 1 unsawn 


1900 


1050 


165 


660 


1050 


1.3 


Unsawn 


2000 


1100 


155 


595 


1050 


1.3 


TP 


No. I 


1600 


875 


155 


595 


850 


1.3 


No. 2 


1350 


750 


155 


595 


700 


1.3 


No. 3 


775 


425 


155 


595 


400 


1.1 


W. Spruce-Pine-Fir 


(WSPF) G=0.37 unseasoned condition 








No. 1 


1150 


625 


125 


455 


650 


1.2 


LHC 


No. 2 


950 


525 


125 


455 


550 


1.2 


No. 1 unsawn 


1350 


725 


125 


455 


650 


1.2 


Western Softwood 


s (WS) G=0.38 unseasoned condition 








No. 1 


1100 


625 


125 


460 


6550 


1.2 


LHC 


No. 2 


925 


525 


125 


460 


550 


1.2 


No. 1 unsawn 


1300 


725 


125 


460 


650 


1.2 


Western Woods 








Unsawn 


1300 


725 


125 


310 


625 


1 


No. 1 


1100 


600 


125 


310 


500 


1 


No. 2 


900 


500 


125 


310 


425 


1 


No. 3 


525 


275 


125 


310 


250 


0.8 


White Woods 


Unsawn 


1300 


725 


125 


310 


625 


1 


TP 


No. 1 


1100 


600 


125 


310 


500 


1 


No. 2 


900 


500 


125 


310 


425 


1 


No. 3 


525 


275 


125 


310 


250 


0.8 



For SI: 1 lbf/in 2 = 6.894 kPa 

a. Source Agencies: 

1. LHC: Log Home Council, National Association of Home Builders 

2. TP: Timber Products Inspection, Inc. 

b. The provided design values are to be used only with logs and/or timbers graded and grade marked by the respective grading rules agency or by one of the manufac- 
turers trained, approved and licensed by the grading rules agency to apply grademarks. 

c. Compression parallel to the grain values have been increased by 10 percent to account for seasoning. For logs that are unseasoned, the design value for compres- 
sion parallel to the grain shall be multiplied by 0.91. 

d. Values listed represent the typical species or species combination design values. Some species, specie combinations, and/or specie designations are not listed due 
to limited use. Other species combinations published by accredited grading agencies are permissible. 

e. All appropriate adjustment factors shall be applied in accordance with Tables 302.2(4) and 302.2(6). 

f. For sawn round timber beams the repetitive member factor, C r , for bending design values, F h , shall not apply to sawn round timber beams in any condition or use. 

g. Sawn round timber beams shall be installed and protected against end moisture so as to achieve equilibrium moisture content in-service. Therefore, the Wet Ser- 
vice Factor, C m , shall not apply. 

h. For sawn round timber beams appropriate form adjustment factors, C n have already been incorporated in the tabulated design values. 



20 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



TABLE 302.2(4) 
ADJUSTMENT FACTORS FOR WALL LOGS 



Diameter (inches) 


Width of Inscribed 
Rectangle (inches) 


Size Factor, CF 


Diameter (inches) 


Width of Inscribed 
Rectangle (inches) 


Size Factor, CF 


4 


3-13/16 


1.14 


13 


10-3/16 


1.02 


5 


4-1/2 


1.12 


14 


10-7/8 


1.01 


6 


5-1/4 


1.1 


15 


11-9/16 


1.0 


7 


5-15/16 


1.08 


16 


12-5/16 


1.0 


8 


6-5/8 


1.07 


17 


13 


0.99 


9 


7-3/8 


1.06 


18 


13-11/16 


0.99 


10 


8-1/16 


1.05 


20 


15-1/8 


0.97 


11 


8-3/4 


1.04 


24 


17-15/16 


0.96 


12 


9-1/2 


1.03 


28 


20-13/16 


0.94 



For SI: 1 inch = 25.4 mm. 



TABLE 302.2(5) 
BASE DESIGN VALUES FOR WALL LOGS 



Species and 

commercial 

grade d 


9 b,c 

Wall-Log Design values in pounds per square inch (Ibf/in ) 


Source Agency 3 


Bending 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cX 


Compression 
parallel to grain 

^dl 


Modulus of 
Elasticity E*10 6 


Appalachian Softwoods 


Premium 


975 


650 


125 


350 


675 


l.l 


TP 


Select 


875 


575 


125 


350 


600 


1.1 


Rustic 


750 


500 


125 


350 


525 


1 


Wall Log 40 


575 


375 


125 


350 


400 


0.8 


Wall Log 30 


425 


275 


125 


350 


300 


0.8 


Aspen G=0.37 unseasoned condition 


Beam 


1150 


750 


125 


310 


800 


1 


LHC 


Header 


925 


625 


125 


310 


675 


1 


Wall 


600 


400 


125 


310 


500 


0.8 


Utility 


400 


275 


125 


310 


450 


0.8 


Premium 


1000 


675 


115 


245 


600 


0.9 


TP 


Select 


900 


600 


115 


245 


525 


0.9 


Rustic 


775 


525 


115 


245 


450 


0.8 


Wall Log 40 


600 


400 


115 


245 


350 


0.7 


Wall Log 30 


450 


300 


115 


245 


250 


0.7 


Bald Cypress (CYP) G=0.43 unseasoned condition 


Beam 


1400 


950 


150 


615 


1250 


1.3 


LHC 


Header 


1150 


775 


150 


615 


1100 


1.3 


Wall 


775 


525 


150 


615 


825 


1 


Utility 


525 


350 


150 


615 


725 


1 


Premium 


1300 


875 


145 


615 


1000 


1.3 


TP 


Select 


1150 


775 


145 


615 


900 


1.3 


Rustic 


1000 


675 


145 


615 


775 


1.1 


Wall Log 40 


775 


500 


145 


615 


575 


1 


Wall Log 30 


575 


375 


145 


615 


425 


1 



(continued) 
STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



21 



GENERAL REQUIREMENTS 







TABLE 302.2(5Hcontinued 
BASE DESIGN VALUES FOR WALL LOGS 






Species and 

commercial 

grade d 


Wall-Log Design values in pounds per square inch (Ibf/in ) 


Source Agency 3 


Bending 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cl 


Compression 
parallel to grain 

^dl 


Modulus of 
Elasticity E*10 6 


Cedar: Incense (IC) G=0.35 unseasoned condition 


Beam 


1300 


900 


155 


565 


1100 


0.9 


LHC 


Header 


1100 


725 


155 


565 


950 


0.9 


Wall 


725 


475 


155 


565 


725 


0.7 


Utility 


475 


325 


155 


565 


650 


0.7 


Premium 


1250 


825 


155 


565 


875 


0.9 


TP 


Select 


1100 


725 


155 


565 


775 


0.9 


Rustic 


950 


625 


155 


565 


675 


0.8 


Wall Log 40 


725 


475 


155 


565 


525 


0.7 


Wall Log 30 


525 


350 


155 


565 


375 


0.7 


Cedar: Northern White 


Premium 


850 


575 


115 


370 


550 


0.7 


TP 


Select 


750 


500 


115 


370 


500 


0.7 


Rustic 


650 


425 


115 


370 


425 


0.6 


Wall Log 40 


500 


325 


115 


370 


325 


0.5 


Wall Log 30 


375 


250 


115 


370 


250 


0.5 


Cedar, Red (Western, RC) G=0.31 unseasoned condition 


Beam 


1150 


775 


130 


440 


1000 


1 


LHC 


Header 


950 


625 


130 


440 


850 


1 


Wall 


625 


425 


130 


440 


650 


0.8 


Utility 


425 


275 


130 


440 


575 


0.8 


Cedar: Western red (WRC) G=0.31 unseasoned condition 


Beam 


1150 


750 


140 


385 


1000 


1 


LHC 


Header 


925 


625 


140 


385 


850 


1 


Wall 


625 


400 


140 


385 


625 


0.8 


Utility 


425 


275 


140 


385 


575 


0.8 


Premium 


1050 


700 


135 


385 


775 


1 


TP 


Select 


925 


625 


135 


385 


700 


1 


Rustic 


825 


550 


135 


385 


600 


0.9 


Wall Log 40 


625 


400 


135 


385 


450 


0.8 


Wall Log 30 


450 


300 


135 


385 


350 


0.8 



(continued) 



22 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



TABLE 302.2(5)— continued 
BASE DESIGN VALUES FOR WALL LOGS 



Species and 

commercial 

grade d 


b,c 

Wall-Log Design values in pounds per square inch (lbf/in 2 ) 


Source Agency 3 


Bending 
F t> 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F ci 


Compression 
parallel to grain 

*dl 


Modulus of 
Elasticity E*10 6 


Cedar: Western red-Canadian (WRC-N) G=0.31 unseasoned condition 


Beam 


1150 


750 


130 


435 


975 


1.1 


LHC 


Header 


925 


625 


130 


435 


850 


1.1 


Wall 


600 


400 


130 


435 


625 


0.9 


Utility 


400 


275 


130 


435 


575 


0.9 


Cedar, White (WC) G=0.30 unseasoned condition 


Beam 


850 


575 


115 


340 


675 


0.6 


LHC 


Header 


700 


475 


115 


340 


575 


0.6 


Wall 


450 


300 


115 


340 


450 


0.5 


Utility 


300 


200 


115 


340 


400 


0.5 


Cedar, Yellow (Western, YC) G=0.42 unseasoned condition 


Beam 


1400 


950 


155 


535 


1150 


1.3 


LHC 


Header 


1150 


775 


155 


535 


950 


1.3 


Wall 


775 


525 


155 


535 


725 


1.1 


Utility 


525 


350 


155 


535 


650 


1.1 


Douglas Fir 


Premium 


1500 


1000 


165 


630 


1050 


1.6 


TP 


Select 


1300 


875 


165 


630 


900 


1.6 


Rustic 


1150 


775 


165 


630 


800 


1.4 


Wall Log 40 


850 


575 


165 


630 


600 


1.3 


Wall Log 30 


650 


425 


165 


630 


450 


1.3 


Douglas Fir(N) 


Premium 


1500 


1000 


175 


600 


1000 


1.5 


TP 


Select 


1300 


875 


175 


600 


875 


1.5 


Rustic 


1150 


775 


175 


600 


750 


1.3 


Wall Log 40 


850 


575 


175 


600 


575 


1.2 


Wall Log 30 


650 


425 


175 


600 


425 


1.2 


Douglas Fir (S) 


Premium 


1400 


950 


165 


520 


925 


1.2 


TP 


Select 


1250 


850 


165 


520 


825 


L2 


Rustic 


1100 


725 


165 


520 


700 


1.1 


Wall Log 40 


825 


550 


165 


520 


525 


1 


Wall Log 30 


625 


425 


165 


520 


400 


1 



(continued) 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



23 



GENERAL REQUIREMENTS 







TABLE 302.2(5)— continued 
BASE DESIGN VALUES FOR WALL LOGS 






Species and 

commercial 

grade d 


o b,c 

Wall-Log Design values in pounds per square inch (Ibf/in^) 


Source Agency 9 


Bending 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F c± 


Compression 
parallel to grain 

^dl 


Modulus of 
Elasticity E*10 6 


Douglas Fir-Larch (DFL) G=0.45 unseasoned condition 


Beam Dense 


1900 


1250 


170 


720 


1500 


1.5 


LHC 


Beam 


1600 


1100 


170 


640 


1300 


1.4 


Header Dense 


1550 


1050 


170 


720 


1300 


1.5 


Header 


1300 


875 


170 


640 


1100 


1.4 


Wall 


875 


575 


170 


640 


825 


1.1 


Utility 


575 


400 


170 


640 


750 


1.1 


Premium 


1500 


1000 


175 


600 


1000 


1.5 


TP 


Select 


1300 


875 


175 


600 


875 


1.5 


Rustic 


1150 


775 


175 


600 


750 


1.3 


Wall Log 40 


850 


575 


175 


600 


575 


1.2 


Wall Log 30 


650 


425 


175 


600 


425 


1.2 


E. Spruce-Pine-Fir (ESPF) G=0.38 unseasoned condition 


Beam 


1050 


725 


125 


430 


850 


1.2 


LHC 


Header 


875 


600 


125 


430 


725 


1.2 


Wall 


575 


375 


125 


430 


550 


1 


Utility 


400 


250 


125 


430 


500 


1 


Eastern Softwoods (ESW) G=0.38 unseasoned condition 


Beam 


1050 


725 


120 


430 


850 


1.2 


LHC 


Header 


875 


600 


120 


430 


725 


1.2 


Wall 


575 


375 


120 


430 


550 


0.9 


Utility 


400 


250 


120 


430 


500 


0.9 


Premium 


975 


650 


125 


350 


675 


1.1 


TP 


Select 


875 


575 


125 


350 


600 


1.1 


Rustic 


750 


500 


125 


350 


525 


1 


Wall Log 40 


575 


375 


125 


350 


400 


0.8 


Wall Log 30 


425 


275 


125 


350 


300 


0.8 



(continued) 



24 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



TABLE 302.2(5)— continued 
BASE DESIGN VALUES FOR WALL LOGS 



Species and 

commercial 

grade d 


, b,c 

Wall-Log Design values in pounds per square inch (Ibf/in ) 


Source Agency 3 


Bending 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cl 


Compression 
parallel to grain 


Modulus of 
Elasticity E*10 6 


Eastern Woods 


Premium 


975 


650 


125 


350 


675 


1.1 


TP 


Select 


875 


575 


125 


350 


600 


LI 


Rustic 


750 


500 


125 


350 


525 


1 


Wall Log 40 


575 


375 


125 


350 


400 


0.8 


Wall Log 30 


425 


275 


125 


350 


300 


0.8 


Fir: Alpine 


Premium 


1000 


675 


125 


405 


700 


1.3 


TP 


Select 


900 


600 


125 


405 


625 


1.3 


Rustic 


775 


525 


125 


405 


550 


1.2 


Wall Log 40 


600 


400 


125 


405 


400 


1.1 


Wall Log 30 


450 


300 


125 


405 


300 


LI 


Fir: Balsam 


Premium 


1300 


875 


145 


615 


1000 


1.3 


TP 


Select 


1150 


775 


145 


615 


900 


1.3 


Rustic 


1000 


675 


145 


615 


775 


1.1 


Wall Log 40 


775 


500 


145 


615 


575 


1 


Wall Log 30 


575 


375 


145 


615 


425 


1 


Fir: White (WF) G=0.37 unseasoned condition 


Beam 


1250 


825 


150 


440 


1000 


1.2 


LHC 


Header 


1000 


675 


150 


440 


875 


1.2 


Wall 


675 


450 


150 


440 


650 


1 


Utility 


450 


300 


150 


440 


600 


1 


Hem-Fir (HF) G=0.39 unseasoned condition 


Beam 


1200 


800 


135 


480 


1000 


1.4 


LHC 


Header 


1000 


675 


135 


480 


875 


1.4 


Wall 


650 


450 


135 


480 


650 


LI 


Utility 


450 


300 


135 


480 


600 


LI 


Premium 


1150 


775 


135 


370 


800 


1.2 


TP 


Select 


1050 


700 


135 


370 


700 


1.2 


Rustic 


900 


600 


135 


370 


625 


1.1 


Wall Log 40 


675 


450 


135 


370 


475 


1 


Wall Log 30 


500 


350 


135 


370 


350 


1 



(continued) 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



25 



GENERAL REQUIREMENTS 



TABLE 302.2(5)— continued 
BASE DESIGN VALUES FOR WALL LOGS 



Species and 

commercial 

grade d 


9 b ' C 

Wall-Log Design values in pounds per square inch (Ibf/in^) 


Source Agency 3 


Bending 
F b 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cl 


Compression 
parallel to grain 

^dl 


Modulus of 
Elasticity E*10 6 


Eastern Hemlock - Tamarack 


Premium 


1250 


850 


155 


550 


875 


1.1 


TP 


Select 


1150 


750 


155 


550 


775 


1.1 


Rustic 


975 


650 


155 


550 


675 


1 


Wall Log 40 


750 


500 


155 


550 


500 


0.9 


Wall Log 30 


550 


375 


155 


550 


375 


0.9 


Hemlock: Western 


Premium 


1300 


875 


165 


410 


950 


1.4 


TP 


Select 


1150 


775 


165 


410 


825 


1.4 


Rustic 


1000 


675 


165 


410 


725 


1.3 


Wall Log 40 


750 


500 


165 


410 


550 


1.1 


Wall Log 30 


575 


375 


165 


410 


400 


1.1 


Larch: Western 


Premium 


1600 


1100 


175 


605 


1150 


1.6 


TP 


Select 


1450 


950 


175 


605 


1000 


1.6 


Rustic 


1250 


825 


175 


605 


875 


1.4 


Wall Log 40 


925 


625 


175 


605 


650 


1.2 


Wall Log 30 


700 


475 


175 


605 


500 


1.2 


Mixed Oak 


Premium 


1250 


850 


155 


795 


775 


1.2 


TP 


Select 


1100 


750 


155 


795 


675 


1.2 


Rustic 


950 


650 


155 


795 


600 


1 


Wall Log 40 


725 


475 


155 


795 


450 


0.9 


Wall Log 30 


550 


375 


155 


795 


325 


0.9 


Mixed Southern Pine (MSP) G=0\48 unseasoned condition 


Beam Dense 


1500 


1000 


165 


680 


1150 


1.2 


LHC 


Beam 


1250 


850 


165 


600 


1000 


1.2 


Header Dense 


1200 


825 


165 


680 


1000 


1.2 


Header 


1050 


700 


165 


600 


850 


1.2 


Wall 


675 


450 


165 


600 


650 


0.9 


Utility 


450 


300 


165 


600 


575 


0.9 


Premium 


1450 


975 


165 


595 


950 


1.3 


TP 


Select 


1300 


850 


165 


595 


850 


1.3 


Rustic 


1100 


750 


165 


595 


750 


1.2 


Wall Log 40 


850 


575 


165 


595 


550 


1 


Wall Log 30 


625 


425 


165 


595 


425 


1 



(continued) 



26 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



TABLE 302.2(5)— continued 
BASE DESIGN VALUES FOR WALL LOGS 



Species and 

commercial 

grade d 


Wall-Log Design values in pounds per square inch (lbf/in z ) 


Source Agency 3 


Bending 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cl 


Compression 
parallel to grain 


Modulus of 
Elasticity E*10 6 


Oak, Red <RO) G=0.57 unseasoned condition 


Beam 


1400 


925 


160 


985 


1000 


1.3 


LHC 


Header 


1150 


775 


160 


985 


850 


1.3 


Wall 


750 


500 


160 


985 


650 


1.1 


Utility 


500 


350 


160 


985 


575 


LI 


Premium 


1250 


850 


155 


820 


775 


1.2 


TP 


Select 


It 00 


750 


155 


820 


675 


1.2 


Rustic 


950 


650 


155 


820 


600 


LI 


Wall Log 40 


725 


475 


155 


820 


450 


1 


Wall Log 30 


550 


375 


155 


820 


325 


1 


Oak, White (WO) G=0.62 unseasoned condition 


Beam 


1450 


975 


210 


1225 


1100 


1 


LHC 


Header 


1200 


800 


210 


1225 


925 


1 


Wall 


775 


525 


210 


1225 


700 


0.8 


Utility 


525 


350 


210 


1225 


625 


0.8 


Premium 


1450 


975 


205 


795 


875 


1.2 


TP 


Select 


1300 


850 


205 


795 


775 


1.2 


Rustic 


1100 


750 


205 


795 


675 


1 


Wall Log 40 


850 


575 


205 


795 


525 


0.9 


Wall Log 30 


625 


425 


205 


795 


375 


0.9 


Pine: Eastern white (EWP) G=0.35 unseasoned condition 


Beam 


1050 


700 


125 


350 


875 


1.1 


LHC 


Header 


875 


575 


125 


350 


725 


LI 


Wall 


575 


375 


125 


350 


550 


0.8 


Utility 


375 


250 


125 


350 


500 


0.8 


Premium 


975 


650 


125 


350 


675 


1.1 


TP 


Select 


875 


575 


125 


350 


600 


1.1 


Rustic 


750 


500 


125 


350 


525 


1 


Wall Log 40 


575 


375 


125 


350 


400 


0.8 


Wall Log 30 


425 


275 


125 


350 


300 


0.8 



(continued) 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



27 



GENERAL REQUIREMENTS 



TABLE 302.2(5)— continued 
BASE DESIGN VALUES FOR WALL LOGS 



Species and 

commercial 

grade d 


o b,c 

Wall-Log Design values in pounds per square inch (Ibf/in ) 


Source Agency 3 


Bending 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cl 


Compression 
parallel to grain 


Modulus of 
Elasticity E*10 6 


Pine: Idaho White 


Premium 


950 


650 


125 


310 


700 


1.3 


TP 


Select 


850 


575 


125 


310 


625 


1.3 


Rustic 


725 


500 


125 


310 


550 


1.1 


Wall Log 40 


550 


375 


125 


310 


400 


1 


Wall Log 30 


425 


275 


125 


310 


300 


1 


Pine: Loblolly (LBP) G=0.47 unseasoned condition 


Beam 


1550 


1050 


160 


595 


1250 


1.5 


LHC 


Header 


1250 


850 


160 


595 


1050 


1.5 


Wall 


825 


550 


160 


595 


800 


1.2 


Utility 


550 


375 


160 


595 


725 


1.2 


Pine: Lodgepole (LPP) G=0.39 unseasoned condition 


Beam 


1150 


775 


125 


400 


925 


1.1 


LHC 


Header 


975 


650 


125 


400 


775 


1.1 


Wall 


625 


425 


125 


400 


600 


0.9 


Utility 


425 


275 


125 


400 


525 


0.9 


Premium 


1100 


725 


125 


395 


725 


1.1 


TP 


Select 


975 


650 


125 


395 


650 


1.1 


Rustic 


825 


550 


125 


395 


575 


1 


Wall Log 40 


625 


425 


125 


395 


425 


0.9 


Wall Log 30 


475 


325 


125 


395 


325 


0.9 


Pine: Longleaf (LLP) G=0.54 unseasoned condition 


Beam 


1850 


1250 


200 


720 


1600 


1.7 


LHC 


Header 


1500 


1000 


200 


720 


1350 


1.7 


Wall 


1000 


675 


200 


720 


1000 


1.3 


Utility 


675 


450 


200 


720 


925 


1.3 


Pine: Northern 


Premium 


1150 


775 


125 


405 


775 


1.1 


TP 


Select 


1000 


675 


125 


405 


675 


1.1 


Rustic 


875 


600 


125 


405 


600 


1 


Wall Log 40 


675 


450 


125 


405 


450 


0.9 


Wall Log 30 


500 


325 


125 


405 


325 


0.9 



(continued) 



28 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



TABLE 302.2(5)— continued 
BASE DESIGN VALUES FOR WALL LOGS 



Species and 

commercial 

grade d 


b,c 
Wall-Log Design values in pounds per square inch (Ibf/in 2 ) 


Source Agency a 


Bending 


Tension parallel 
to grain F, 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cl 


Compression 
parallel to grain 


Modulus of 
Elasticity E*10 6 


Pine: Ponderosa (PP) G=0.39 unseasoned condition 


Beam 


1100 


725 


130 


440 


875 


1.1 


LHC 


Header 


900 


600 


130 


440 


750 


1.1 


Wall 


600 


400 


130 


440 


550 


0.8 


Utility 


400 


275 


130 


440 


500 


0.8 


Premium 


1000 


675 


125 


440 


700 


1.1 


TP 


Select 


900 


600 


125 


440 


600 


1.1 


Rustic 


775 


525 


125 


440 


525 


1 


Wall Log 40 


600 


400 


125 


440 


400 


0.8 


Wall Log 30 


450 


300 


125 


440 


300 


0.8 


Ponderosa Pine - Lodgepole Pine (PP-LP) 


Premium 


1000 


675 


125 


395 


700 


LI 


TP 


Select 


900 


600 


125 


395 


600 


LI 


Rustic 


775 


525 


125 


395 


525 


1 


Wall Log 40 


600 


400 


125 


395 


400 


0.8 


Wall Log 30 


450 


300 


125 


395 


300 


0.8 


Ponderosa Pine - Sugar Pine (PP-SP) 


Premium 


1000 


675 


125 


345 


700 


1.1 


TP 


Select 


900 


600 


125 


345 


600 


1.1 


Rustic 


775 


525 


125 


345 


525 


1 


Wall Log 40 


600 


400 


125 


345 


400 


0.8 


Wall Log 30 


450 


300 


125 


345 


300 


0.8 


Pine: Red (RP) G=0.42 unseasoned condition 


Beam 


1250 


825 


125 


410 


975 


1.4 


LHC 


Header 


1000 


675 


125 


410 


825 


1.4 


Wall 


675 


450 


125 


410 


625 


LI 


Utility 


450 


300 


125 


410 


550 


1.1 


Pine: Red-Canadian (RP-N) G=0.39 unseasoned condition 


Beam 


1050 


725 


130 


440 


850 


1.1 


LHC 


Header 


875 


600 


130 


440 


725 


LI 


Wall 


575 


375 


130 


440 


550 


0.9 


Utility 


400 


250 


130 


440 


475 


0.9 



(continued) 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



29 



GENERAL REQUIREMENTS 



TABLE 302.2(5)— continued 
BASE DESIGN VALUES FOR WALL LOGS 



Species and 

commercial 

grade d 


, b,c 

Wall-Log Design values in pounds per square inch (lbf/in^) 


Source Agency 3 


Bending 


Tension parallel 
to grain F f 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F ei 


Compression 
parallel to grain 


Modulus of 
Elasticity E*10 6 


Pine: Sugar (SUP) G=0.34 unseasoned condition 


Beam 


1100 


725 


130 


345 


925 


1.1 


LHC 


Header 


900 


600 


130 


345 


775 


1.1 


Wall 


600 


400 


130 


345 


600 


0.9 


Utility 


400 


275 


130 


345 


525 


0.9 


Premium 


1000 


675 


125 


345 


725 


1.1 


TP 


Select 


900 


600 


125 


345 


650 


1.1 


Rustic 


775 


525 


125 


345 


550 


1 


Wall Log 40 


600 


400 


125 


345 


425 


0.9 


Wall Log 30 


450 


300 


125 


345 


325 


0.9 


Pine: Western white (WWP) G=0.35 unseasoned condition 


Beam 


1000 


700 


125 


315 


900 


1.3 


LHC 


Header 


850 


575 


125 


315 


750 


1.3 


Wall 


550 


375 


125 


315 


575 


1 


Utility 


375 


250 


125 


315 


500 


1 


Redwood 


Premium 


1150 


800 


145 


420 


875 


1 


TP 


Select 


1050 


700 


145 


420 


775 


1 


Rustic 


900 


600 


145 


420 


675 


0.9 


Wall Log 40 


675 


450 


145 


420 


500 


0.8 


Wall Log 30 


500 


350 


145 


420 


375 


0.8 


Southern Pine (SP) G=0.48 unseasoned condition 


Beam Dense 


1900 


1300 


170 


680 


1550 


1.6 


LHC 


Beam 


1650 


1100 


170 


600 


1350 


1.5 


Header Dense 


1550 


1050 


170 


680 


1300 


1.6 


Header 


1350 


900 


170 


600 


1150 


1.5 


Wall 


875 


600 


170 


600 


850 


1.2 


Utility 


600 


400 


170 


600 


775 


1.2 


Premium 


1450 


950 


165 


515 


1000 


1.5 


TP 


Select 


1250 


850 


165 


515 


875 


1.5 


Rustic 


1100 


750 


165 


515 


775 


1.3 


Wall Log 40 


825 


550 


165 


515 


575 


1.2 


Wall Log 30 


625 


425 


165 


515 


425 


1.2 



(continued) 



30 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



TABLE 302.2(5)— continued 
BASE DESIGN VALUES FOR WALL LOGS 



Species and 

commercial 

grade d 


Wall-Log Design values in pounds per square inch (Ibf/in ) 


Source Agency 3 


Bending 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F ci 


Compression 
parallel to grain 


Modulus of 
Elasticity E*10 6 


Spruce: Eastern (ES) G=0.38 unseasoned condition 


Beam 


1050 


725 


125 


430 


850 


1.3 


LHC 


Header 


875 


600 


125 


430 


725 


1.3 


Wall 


575 


375 


125 


430 


550 


1.1 


Utility 


400 


250 


125 


430 


500 


1.1 


Premium 


1000 


675 


125 


390 


700 


1.2 


TP 


Select 


900 


600 


125 


390 


625 


1.2 


Rustic 


775 


525 


125 


390 


525 


1.1 


Wall Log 40 


575 


400 


125 


390 


400 


1 


Wall Log 30 


450 


300 


125 


390 


300 


1 


Spruce: Engelmann G=0.33 unseasoned condition 


Premium 


950 


650 


125 


320 


600 


1.1 


TP 


Select 


850 


575 


125 


320 


525 


1.1 


Rustic 


725 


500 


125 


320 


450 


1 


Wall Log 40 


550 


375 


125 


320 


350 


0.9 


Wall Log 30 


425 


275 


125 


320 


250 


0.9 


Engelmann Spruce - Alpine Fir (ES-AF) 


Premium 


950 


650 


125 


320 


600 


LI 


TP 


Select 


850 


575 


125 


320 


525 


LI 


Rustic 


725 


500 


125 


320 


450 


1 


Wall Log 40 


550 


375 


125 


320 


350 


0.9 


Wall Log 30 


425 


275 


125 


320 


250 


0.9 


Engelmann Spruce - Lodgepole Pine (ES-LP) 


Premium 


950 


650 


125 


320 


600 


1.1 


TP 


Select 


850 


575 


125 


320 


525 


LI 


Rustic 


725 


500 


125 


320 


450 


1 


Wall Log 40 


550 


375 


125 


320 


350 


0.9 


Wall Log 30 


425 


275 


125 


320 


250 


0.9 


Engelmann Spruce - Alpine Fir - Lodgepole Pine (ES-AF-LP) 


Premium 


950 


650 


125 


320 


600 


1.1 


TP 


Select 


850 


575 


125 


320 


525 


1.1 


Rustic 


725 


500 


125 


320 


450 


1 


Wall Log 40 


550 


375 


125 


320 


350 


0.9 


Wall Log 30 


425 


275 


125 


320 


250 


0.9 


Spruce - Pine - Fir 


Premium 


950 


650 


125 


305 


600 


1.1 


TP 


Select 


850 


575 


125 


305 


525 


1.1 


Rustic 


725 


500 


125 


305 


450 


1 


Wall Log 40 


550 


375 


125 


305 


350 


0.9 


Wall Log 30 


425 


275 


125 


305 


250 


0.9 



(continued) 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



31 



GENERAL REQUIREMENTS 



TABLE 302.2(5)— continued 
BASE DESIGN VALUES FOR WALL LOGS 



Species and 

commercial 

grade d 


n b,C 

Wall-Log Design values in pounds per square inch (Ibf/in ) 


Source Agency 3 


Bending 
Ft, 


Tension parallel 
to grain F t 


Shear 

parallel to 

grain F v 


Compression 

perpendicular to 

grain F cl 


Compression 
parallel to grain 


Modulus of 
Elasticity E*10 6 


Tamarack 


Premium 


1400 


950 


155 


595 


975 


1.3 


TP 


Select 


1250 


850 _j 


155 


595 


875 


1.3 


Rustic 


1100 


725 


155 


595 


750 


1.2 


Wall Log 40 


825 


550 


155 


595 


575 


1.1 


Wall Log 30 


625 


425 


155 


595 


425 


1.1 


W. Spruce-Pine-Fir (WSPF) G=0.37 unseasoned condition 


Beam 


1050 


725 


120 


410 


775 


1.2 


LHC 


Header 


875 


600 


120 


410 


675 


1.2 


Wall 


575 


375 


120 


410 


500 


1 


Utility 


400 


250 


120 


410 


450 


1 


Western Softwoods (WS) G=0.38 unseasoned condition 


Beam 


1050 


700 


120 


410 


775 


1.2 


LHC 


Header 


875 


575 


120 


410 


675 


1.2 


Wall 


575 


375 


120 


410 


500 


0.9 


Utility 


375 


250 


120 


410 


450 


0.9 


Western Woods 


Premium 


950 


625 


125 


310 


600 


1 


TP 


Select 


850 


575 


125 


310 


525 


1 


Rustic 


725 


500 


125 


310 


450 


0.9 


Wall Log 40 


550 


375 


125 


310 


350 


0.8 


Wall Log 30 


425 


275 


125 


310 


250 


0.8 


White Woods 


Premium 


950 


625 


125 


310 


600 


1 


TP 


Select 


850 


575 


125 


310 


525 


1 


Rustic 


725 


500 


125 


310 


450 


0.9 


Wall Log 40 


550 


375 


125 


310 


350 


0.8 


Wall Log 30 


425 


275 


125 


310 


250 


0.8 


Yellow Poplar 


Premium 


1100 


725 


135 


420 


675 


1.3 


TP 


Select 


950 


650 


135 


420 


600 


1.3 


Rustic 


825 


550 


135 


420 


525 


1.3 


Wall Log 40 


625 


425 


135 


420 


400 


1 


Wall Log 30 


475 


325 


135 


420 


300 


1 



For SI: 1 lbf/in 2 = 6.89 kPa 

a. Source Agencies: 

1. LHC: Log Home Council, National Association of Home Builders 

2. TP: Timber Products Inspection, Inc. 

b. All appropriate adjustment factors shall be applied in accordance with Tables 302.2(4) and 302.2(6). 

c. Compression parallel to the grain values have been increased by 1 percent to account for seasoning. For logs that are unseasoned, the design value for compres- 
sion parallel to the grain shall be multiplied by 0.91. 

d. Values listed represent the typical species or species combination design values. Other species combinations published by accredited grading agencies are permis- 
sible. 



32 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



TABLE 302.2(6) 
APPLICABILITY OF ADJUSTMENT FACTORS FOR WALL LOGS AND SRTBs 





c 
o 

"OIL 

CO 

o 


o 

*3 

CO 
LL 

Q) 
O 

E 

</> 

Q) 

5 


o 
o 

CO 
LL 

<D 

B 

ro 

a> 
a 
£ 
a> 
1- 


> 

5 o 
<f> o 

E u_ 

(CI 
0) 

m 


2 
o 

CD 
(JL 

<U 
N 

a) 


2 

o 

CO 

LL 
<D 

D 

J2 
LL 


O 

o 

CO 
LL 
U) 

G 

o 


0) 

£ 
S o 

> CO 

£ tL 

a! 

Q. 

a> 


I*L 
</> 2 

c ° 

*= CO 
E LL 

3 
O 

o 


(/> 

CO 

CD 

c 

ft 

D> CO 

.£ "- 

o 

m 


F b ' = F h x 


C D 


C M 


c, 


Q 


C F 


Cfu 


C, 


c r 


— 


— 


F t ' = F t x 


Q> 


C M 


c, 


— 


C F 





c, 


_ 


__ 





F v ' = F v x 


c D 


C M 


c, 


— 








Q 


— 


— 


— 


Fc±'=F c ±x 





C M 


c, 


— 








C; 








™_ 


F c '=F c x 


Q> 


C M 


c, 


_ 


C F 





C; 


— 


c P 


— 


E' = Ex 


_ 


Cm 


c, 


— 


~~~ 





Ci 


— 


_ 


c> 



a. Load Duration Factor: Values shown within Tables 302.2(3) and (5) are based upon norma] load durations. 

b. Wet Service Factor: Logs are to be installed and protected against moisture so as to achieve equilibrium moisture content in-service. Therefore, the Wet Service 
Factor shall not apply. 

c. Temperature Factor: Per AF&PA NDS. 

d. Beam Stability Factor: Per AF&PA NDS. 

e. Size Factor (SRTB and USRTB): Bending design values, F h> shown within Table 302.2(5) are calculated for an inscribed member width of 1 2 inches (305 mm). For 
gravity loads, the vertical dimension of the wall log is the width. For lateral loads, the horizontal dimension of the wall log is the width. The bending design value, 
F h , shown with table 302.2(5) shall be multiplied by the size factor, 

^F = (12/d) <l-0' 

Where: d = the width of the inscribed rectangle of the wall log relative to the direction of the imposed load being analyzed. 

Size Factor (wall logs): Bending design values, F h , shown within Table 302.2(3) are calculated for a 2" x 2" (5 1 mm x 5 1 mm). Currently ASTM D 3957 does not 
explicitly require a size reduction for SRTB values. However, this is commonly performed within the industry and the applicability of this factor is at the designer's 
discretion. Should a size reduction be necessary, the bending design value, F h , show within Table 302.2(3) shall be multiplied by the size factor, 

C F = (2.2568/d) ,/9 

Where: d = log diameter 
Flat Use Factor: Not applicable for any use of wall logs or sawn round timbers. 
Incising Factor: Per AF&PA NDS. 

Repetitive Member Factor: Not applicable for any use of wall logs or sawn round timbers. 
Buckling Stiffness Factor: Not applicable for any use of wall logs or sawn round timbers. 
Column Stabilift Factor: Per AF&PA NDS. 



f. 



RECTANGLE 2 



RECTANGLE 1 




- RECTANGLE 2 



RECTANGLE 1 



RECTANGLE 1 



RECTANGLE 2 




RECTANGLE 1 



RECTANGLE 2 



For SI: 1 inch = 25.4 mm. 



FIGURE 302.2.3.6 
LOG THICKNESS 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



33 



GENERAL REQUIREMENTS 



302.2.3.3.4 Test procedure. Specific gravity shall be 
determined in accordance with ASTM D 2395. 

302.2.3.4 Section properties. Section properties for 
Sawn Round and Unsawn Round Timber Beams shall be 
in accordance with Table 302.2(2). Section properties for 
wall logs shall be determined using the log height and 
width dimensions of the largest rectangle that can be 
inscribed within the profile in accordance with Sections 

302.2.3.5 and 302.2.3.6. 

Exception: When a square is inscribed within the 
profile of a round log, the section properties of the 
inscribed square may be increased by the factors 
shown in Table 302.2(4). 

302.2.3.5 Log stack height. For calculation purposes, 
the log stack height in inches (H L ) shall equal the average 
vertical dimension of the log at time of manufacture as 
described in Figure 302.2.3.6 as follows: 

1 . For logs profiled with horizontal bearing surfaces, 
H L is the dimension between bearing surfaces. 

2. For all other log profiles, the manufacturer shall 
provide the dimension for H L . 

302.2.3.6 Log thickness. For calculation purposes, the 
log thickness (W L ) shall equal the average cross sectional 
area divided by the stack height. 

302.2.3.7 Log density. The density of the log shall be 
calculated as follows: 

Density (lb/ft 3 ) = 62.4 x { G/[l+(0.009x GxMC D )]} 
x(l+MC o /100) 

where: 

G = Specific gravity. 

MC D = Design moisture content. 

302.2.3.8 Log weight. Log weights shall be calculated as 
follows: 

1. The weight of the log wall in pounds per square 
foot (psf) shall be calculated by multiplying the 
density times W L /12. 

2. The weight of the log wall in pounds per lineal foot 
(plf) shall be calculated by multiplying the weight 
of the wall (psf) times the overall log wall height 
(in feet). 

3. The weight of an individual log in pounds per lin- 
eal foot (plf) shall be calculated by multiplying 
density times (W L /12)(H L /\2). 

302.2.4 Notching and boring. Notching and boring of logs 
used in structural applications shall be in accordance with 
this section and Figure 302.2.4. 

Exception: When specific engineering analysis is pro- 
vided by a registered design professional. 

302.2.4.1 Wall logs. Wall logs that are fully supported 
throughout their length shall be permitted to have up to 
two-thirds the cross-section removed to accommodate 
joints, corners, and intersecting walls. 



302.2.4.2 Interlocking log notches. Interlocking log 
notches shall resist the separation of the two log mem- 
bers it joins, or shall have mechanical fasteners that resist 
separation. 

302.2.4.3 Kerfing. Where kerfing is provided in logs 
used in walls the depth of the kerf shall be no deeper than 
HJ2. The sum of the depths of the kerf and cope shall not 
exceed HJ2. Where beams are kerfed, the net section 
shall be used to determine the section capacity. 

302.2.4.4 Notches. Notches on the edges of bending 
members shall not be located in the middle one-third of 
the span. Notches in the outer thirds of the span shall not 
exceed one-sixth of the actual member depth and shall 
not be longer than one-third of the depth of the member. 
Where notches are made at the supports, they shall not 
exceed one-fourth the actual log depth. 

302.2.4.5 Round holes. Round holes in bending mem- 
bers shall be limited in diameter to one-third the mini- 
mum log dimension at the location of the hole. The edge 
of the round hole shall not be closer than 2 inches (5 1 
mm) to the edge of the log. Edges of round holes shall not 
be located closer than 2 inches (51 mm) to the edge of a 
notch. 

302.2.4.6 Rectangular holes. Depth of rectangular 
holes in bending members located in the outer thirds of 
the span shall not exceed one-fourth the member depth at 
the location of the hole. Depth of rectangular holes 
located in the middle one-third of the span shall not 
exceed one-third the member depth at the location of the 
hole. Width of rectangular holes in the outer thirds of the 
span shall not exceed one- third the member depth at the 
location of the hole. Width of rectangular holes in the 
middle third of the span shall not exceed one-half the 
member depth at the location of the hole. The edge of the 
rectangular hole shall not be closer than 2 inches (51 
mm) to the edge of the log. Edges of rectangular holes 
shall not be located closer than 2 inches (51 mm) to the 
edge of a notch. 

302.2.4.7 Spacing of notches and holes. Spacing 
between notches and holes in bending members shall be 
limited to the greater of at least twice the hole diameter or 
twice the notch width, using the larger diameter or width 
of the two. 

Exception: Wall logs, or sections of wall logs, when 
they are fully supported along their length. 

302.2.4.8 Shear design. For bending members with cir- 
cular cross-section and notched on the tension face in 
accordance with the limits of this section, the allowable 
design shear shall be calculated in accordance with the 
AF&PA NDS. 

302.2.4.9 Net section. The net section area shall be used 
in calculating the load carrying capacity of a structural 
member. The net section area is obtained by deducting 
from the gross section area the projected area of all mate- 
rial removed by boring, notching, or other means. 



34 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



d = depth of log at location of notch or hole measured perpendicular to the direction of the hole or notch. 

in = length of notch 

D r = diameter of round hole 

D s = depth of rectangular hole 

W s = width of rectangular hole 

L = clear span of bending member 



< 1 /4d 



> r 



,y^ 



,<- 



\ Dr 

larger of 2 D r ^ 



or 2/n or 2" 



< 1 /3d! 



-?'- 



> T 



v^ 



> 2" 



/- 



-/- 



Jarger of 



< 1 / 3 d 



2 D r or 

2W Q 



-^ 

> 2" 

< 1 /3d; 



-y— 
* * 

1 W- < Vo d ' 



\ D r 
> 2" 



> 2" 



/- 



larger of 2 D| 



W s < 1 /3d 



y 



< 1 /ed 



2lnor2"'\ 



< % d 

-/— - 

> 2" 



71^- 



^ 



/n< 1 / 3 d' 



1 / 3 L 



y 3 L 



In < 1 / 3 d 



^ 



y 3 L 



For SI: 1 inch = 25.4 mm. 



FIGURE 302.2.4 
NOTCHING AND BORING 



TABLE 304.2(1) 
MOISTURE CONTENT OF SELECTED WOOD SPECIES AT FIBER SATURATION (MCFS) 



Wood Species/Groups 


Average moisture present at fiber saturation (MCFS) 


Yellow Poplar 


31 


Engelmann Spruce 
Red Oak 


30 


Alaska Cedar 
Douglas Fir-Larch 
Western Hemlock 


28 


Southern Pine 


26 


Redwood 


22 


Cypress 


30 


Western Red Cedar 


18 


Sitka Spruce 


28 


All other species 


30 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



35 



GENERAL REQUIREMENTS 



TABLE 304.2(2) 
SHRINKAGE COEFFICIENTS 



Shrinkage* (%) from green 
to ovendry moisture content 



Species 



Radial Tangential Species 



Hardwoods 

Alder, red 4.4 7.3 
Ash 

Black 5.0 7.8 

Green 4.6 7.1 

White 4.9 7.8 
Aspen 

Bigtooth 3.3 7.9 

Quaking 3.5 6.7 

Basswood, American 6.6 9.3 

Beech, American 5.5 11.9 
Birch 

Paper 6.3 8.6 

Sweet 6.5 9.0 

Yellow 7.3 9.5 

Butternut 3.4 6.4 

Cherry, black 3.7 7.1 
Cottonwood 

Black 3.6 8.6 

Eastern 3.9 9,2 
Elm 

American 4.2 9.5 

Rock 4.8 8.1 

Hackberry 4.8 8.9 

Hickory 7.4 11.4 

Magnolia, southern 5.4 6.6 
Maple 

Bigleaf 3.7 7.1 

Red 4.0 8.2 

Silver 3,0 7.2 

Sugar 4.8 9.9 
Oak 

Northern red 4.0 8.6 

Northern white 5.6 10.6 

Southern red 4.7 11.3 

Southern white (chestnut) 5.3 10.8 

Pecan 4.9 8.9 

Sweetgum 5.3 10.2 

Sycamore, American 5.0 8.4 

Tanoak 4.9 11.7 
Tupelo 

Black 5.1 8.7 

Water 4.2 7.6 

Walnut, black 5.5 7.8 

Willow, black 3.3 8.7 

Yellow-poplar 4.6 8.2 



Shrinkage* (%) from green 
to ovendry moisture content 

Radial Tangential 



Softwoods 

Baldcypress 
Cedar 

Alaska 

Atlantic white 

Eastern redcedar 

Incense 

Northern white 

Port-Orford 

Western redcedar 
Douglas-fir 

Coasf 

Interior north 5 

Interior west" 
Fir 

Balsam 

California red 

Grand 

Nobel 

Pacific silver 

Subalpine 

White 
Hemlock 

Eastern 

Western 
Larch, western 
Pine 

Eastern pine 

Jack 

Lodgepole 

Ponderosa 

Red 

Southern 
Loblolly 
Longleaf 
Shortleaf 
Slash 

Sugar 

Western white 
Redwood 

Old growth 

Young growth 
Spruce 

Engelmann 

Red 

Sitka 

White 



3.8 



6.2 



2.8 


6.0 


2.9 


5.4 


3.1 


4.7 


3.3 


5.2 


2.2 


4.9 


4.6 


6.9 


2.4 


5.0 


4.8 


7.6 


3.8 


6.9 


4.8 


7.5 


2.9 


6.9 


4.5 


7.9 


3.4 


7.5 


4.3 


8.3 


4.4 


9.2 


2.6 


7.4 


3.3 


7.0 


3.0 


6.8 


4.2 


7.8 


4.5 


9.1 


2.1 


6.1 


3.7 


6.6 


4.3 


6.7 


3.9 


6.2 


3.8 


7.2 


4.8 


7.4 


5.1 


7.5 


4.6 


7.7 


5.4 


7.6 


2.9 


5.6 


4.1 


7.4 


2.6 


4.4 


2.2 


4.9 


3.8 


7.1 


3.8 


7.8 


4.3 


7.5 


4.7 


8.2 



"Expressed as a percentage of the green dimension. 



36 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



TABLE 304.2(3) 
PRESCRIBED SETTLING ALLOWANCE FOR NONHORIZONTAL BEARING SURFACES 



Cope angle from 
horizontal (A)(degrees) 


Notch-bearing width (NB), min. each 
side 


Settling Allowance (per course) 


c an 


Tan" 1 (depth of cope/ 0.5 BC]) 


NB = (BC/2)/CosA 


NB xSinA 





0°to 10° 


5/8" 


1/8" 


1.00 


10° to 23.5° 


11/16" 


5/16" 


1.10 


23.5° to 38° 


13/16" 


9/16" 


1.30 


38° to 46.5° 


15/16" 


11/16" 


1.50 


47° to 52° 


1-1/16" 


7/8" 


1.70 


53° to 60° 


1-1/4" 


1-1/8" 


2.00 



For SI: 1 inch = 25.4 mm, 1 degree = 0.0175 rad. 
Notes: 

1. BC = the greatest dimension between the points of the cope 

2. For round bearing surfaces (e.g., cope), establish the angle from horizontal by connecting a line from the outer contact point to the top center point of the cope. Using 
the contact along the representative line, divide the actual contact area by the C AN factor to determine the equivalent horizontal bearing area. 

3. The settling allowance for compaction shown is based on a requirement for horizontal bearing of l'/ 4 inches (32 mm). 

TABLE 304.2(4) 
PRESCRIBED SETTLING ALLOWANCE DUE TO SHRINKAGE 



Climate 
Zone 2 


Service 

Moisture 

Content 

(MCS) 


Radial Shrinkage Coefficient 
= 2.5 for Cedar, Redwood 


Radial Shrinkage Coefficient 
= 4 for White Woods 


Radial Shrinkage Coefficient 
= 4.7 for Oak, Maple 


MC D _ J \9% 
MC 


MC D = 23%MC 


MC D - 30% 
MC 


MC D = 
19% MC 


MC D = 
23% MC 


MC D = 
30% MC 


MC D ^ 
19% MC 


MC D = 
23% MC 


MC D = 
30% MC 


Dry 


Ranging 
from 8% to 

13%; 

averaging 

10% 


3 / 32 -in. 

per ft. 

or 0.8% of 

involved 

height 


% -in. 

per ft. 
or l%of 
involved 

height 


13/ 

64-m P er 
ft. or 1.7% 
of involved 

height 


9 / 64 -in. per ft. 

or 1.2% of 

involved 

height 


13 / 64 -in. per ft. 
or 1.7% of 
involved 

height 


5 / 16 -in. per ft. 

or 2.6% of 
involved 

height 


1 ^-in-Per 

ft. or 1.4% of 

involved 

height 


'/ 4 -in. per ft. 

or 2.1% of 

involved 

height 


3 / 8 -in. per ft. 

or 3.1% of 

involved 

height 


Moist 


Ranging 
from 12% to 

15%; 
averaging 

13% 


V 16 -in. per ft. 

or 0.5% of 

involved 

height 


3 / 32 -in. 

per ft. or 0.8% 

of involved 

height 


n / 64 -in. per 

ft. or 1.4% 

of involved 

height 


/ 32 -in. per ft. 

or 0.8% of 

involved 

height 


5 / 32 -in. per ft. 

or 1.3% of 

involved 

height 


17 / 64 -in. per 

ft. or 2.2% of 

involved 

height 


7 / 64 -in. per 

ft.nor 0.9% 

of involved 

height 


3 /, 6 -in. per ft. 

or 1.6% of 

involved 

height 


5 /' 6 -in. per ft. 

or 2.6% of 

involved 

height 


Warm- 
Humid 


Ranging 

from 13% to 

15%; 

averaging 

14% 


3 / 64 -in. 

per ft. 

or 0.4% 

of involved 

height 


3 / 32 -in. 

per ft. or 0.8% 

of involved 

height 


5 / 3 2-in. per 

ft. or 1.3% 

of involved 

height 


5 / 64 -in. per ft. 

or 0.7% of 

involved 

height 


9 / 64 -in. per ft. 

or 1.2% of 

involved 

height 


V 4 -in. per ft. 

or 2.1% of 

involved 

height 


3 / 32 -in. per 

ft. or 0.8% of 

involved 

height 


n / 64 -in.perft. 

or 1.4% of 

involved 

height 


l9 / 64 -in, per ft, 

or 2.5% of 

involved 

height 


Marine 


Ranging 

from 1 3% to 

17%; 

averaging 

15% 


per ft. or 

0.4% of 

involved 

height 


5 / 64 -in. per ft. 

or 0.7% of 

involved 

height 


5 / 39 -in. per 

ft. or 1.3% 

of involved 

height 


V 16 -in. per ft. 

or 0.5% of 

involved 

height 


V 8 -in. per ft. 

or l%of 

involved 

height 


15 / 64 -in. per 

ft. 

or 2% of 

involved 

height 


5 / 64 -in. per 

ft. or 0.7% of 

involved 

height 


5 / 32 -in. per ft. 

or 1.3% of 

involved 

height 


9 / 3r in. per ft. 

or 2.3% of 

involved 

height 



For SI: 1 inch = 25.4 mm, 1 foot = 305 mm. 
Notes to Table 304.2(4): 

1. Tabulated settling due to shrinkage is based on the average MC S for the climate zone. 

2. Refer to Figure 304.2.2.3 Climate Zone Map to identify the appropriate climate zone. The climate zones are further defined below: 

Marine (C) Definition - Locations meeting all four criteria: 

1 . Mean temperature of coldest month between -3°C (27°F) and 18°C (65°F). 

2. Warmest month mean < 22°C (72°F). 

3. At least four months with mean temperatures over 10°C (5 0°F). 

4. Dry season in summer. The month with the heaviest precipitation in the cold season has at least three times as much precipitation as the month with the 
least precipitation in the rest of the year. The cold season is October through March in the Northern Hemisphere and April through September in the South- 
ern Hemisphere. 

Dry (B) Definition - Locations meeting the following criteria: 

1. Not Marine and 

2. P m < 0.44 x (7> - 19.5) [P cm <2.0x(T c + 7) in SI units] where: 

P = annual precipitation in inches (cm) 
T - annual mean temperature in °F (°C) 

Moist (A) Definition - Locations that are not Marine and not Dry. 

Warm Humid Definition - Locations shall be defined as locations where either of the following conditions occur: 

1 . 67°F (19.4°C) or higher wet-bulb temperature for 3,000 or more hours during the warmest six consecutive months of the year; 

2. 73°F (22.8°C) or higher wet-bulb temperature for 1,500 or more hours during the warmest six consecutive months of the year. 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



37 



GENERAL REQUIREMENTS 



302.2.5 Wood treatments. Use of wood treatments shall 
comply with the requirements of this section. 

302.2.5.1 Tabulated design values. Tabulated design 
values apply to logs pressure treated by an approved pro- 
cess and preservative. Load duration factors greater than 
1.6 shall not apply to structural members pres- 
sure-treated with water-borne preservatives. 

302.2.5.2 Logs required to be preservative treated. 

Logs required by the applicable code to be preservative 
treated shall be treated using processes and preservatives 
in accordance with AWPA Standards and shall bear the 
quality mark or certificate of treatment issued by an 
accredited third party agency. 

302.2.5.3 Design values and adjustment factors. Spe- 
cific design values or applicable adjustment factors for 
logs pressure- treated with fire-retardant chemicals shall 
be determined in accordance with the applicable code or 
standard. 

302.2.6 Handling and storage. Logs shall be handled and 
stored at the job site in accordance with the manufacturer's 
specifications and in a manner to protect the structural integ- 
rity of the logs. 

302.3 Mechanical connections and fasteners. Mechanical 
connections and fasteners shall be designed and installed in 
accordance with AF&PA NDS specifications and shall con- 
form to the standards specified in this section. 

302.3.1 Bolts. Bolts shall comply with ANS1/ASME B 
18.2.1 Square and Hex Bolts and Screws (Inch Series). 

302.3.2 Lag screws. Lag screws or lag bolts shall comply 
with ANSI/ASME B18.2.1 Square and Hex Bolts and 
Screws (Inch Series). 

302.3.3 Nails. Nails shall comply with ASTM F 1667, Stan- 
dard Specification for Driven Fasteners: Nails, Spikes and 
Staples. 

302.3.4 Screws. Screws shall comply with ANSI/ASME 
B 18.6.1, Wood Screws (Inch Series), 

302.3.5 Metal connectors. Where metal plate or strapping 
size and gage are specified, minimum ASTM A 653, Struc- 
tural Quality, Grade 33 steel shall be used. 

302.3.6 Wood dowels. Wood dowels shall be permitted in 
connection design using NDS yield limit equations I, II, III, 
and IV. Bending yield strength, Fyb, for wood dowels shall 
be derived from the modulus of rupture (MOR, avg.) in 
Table 2 of ASTM D 2555. Listed MOR values shall be per- 
mitted to be adjusted to 12 percent moisture content using 
the ratios provided in Table Xl.l of ASTM D 2555. An 
additional yield mode V shall be determined as follows: 



Allowable shear stress, F vp 

1,365G/ 926 G / - 778 

where: 



in a wood dowel - 



Gj = Specific gravity for the timber. 
G p - Specific gravity for the dowel. 
G p > G, 



Allowable lateral design value (Z) for a doweled connection 
shall be the lesser of yield modes I, II, III, and IV from the 
NDS, and yield mode V determined as follows: 

Z„ = F vp (pD2)/4S'mg\e Shear 

Z v = F vp fpD2)/2DoubleShear 

where: 

D = Diameter of a dowel; 1.5 inches (38 mm) > D > 
0.75 inch (19 mm). 

302.3.7 Other connectors. Other mechanical connections 
and fasteners shall demonstrate by analysis based on recog- 
nized theory, full scale or prototype loading tests, studies of 
model analogues, that the material, assembly, structure or 
design will perform satisfactorily in its intended end use. 



SECTION 303 

FIRE-RESISTANCE RATINGS OF LOGS AND LOG 

ASSEMBLIES 

303.1 Fire resistance. Fire resistance of logs and log assem- 
blies shall be in accordance with the provisions of this section. 

303.2 Fire resistance ratings of log walls. Fire resistance rat- 
ings shall be in accordance with the requirements of this sec- 
tion. 

303.2.1 Prescriptive rating. Log walls are equivalent to 
1-hour fire-resistive-rated construction where the smallest 
horizontal dimension of each log is at least 6 inches (152 
mm). 

303.2.2 Calculated rating. Log wall fire resistance shall be 
calculated in accordance with the AF&PA National Design 
Specification (AF&PA AFPA NDS) for Wood Construc- 
tion, Chapter 16. 

303.2.3 Tested rating. Log wall fire resistance shall be 
tested in accordance with ASTM E 119 by an accredited 
laboratory. 

303.3 Fire resistance of log columns and beams. Fire resis- 
tance of columns and beams shall be determined in accordance 
with the International Building Code. 

303.4 Log thickness. For the purposes of Section 303, the log 
thickness shall be the smallest horizontal dimension from the 
outside face to the inside face of the log wall. Sealant systems 
shall not be included in determining the log thickness unless 
the sealant system is fire-resistive rated. 

303.5 Sealing system. Sealant systems used to protect joints as 
part of the fire-resistive rated assembly shall be in accordance 
with the requirements of either ASTM E 1966 or UL 2079. 

303.6 Fire blocking. Fire blocking shall be in accordance with 
the applicable code. 

Exception: Fire blocking is not required within concealed 
horizontal spaces between successive courses of logs. 

303.7 Fastener protection. Where minimum 1 -hour fire resis- 
tance is required, connectors and fasteners shall be protected 
from fire exposure by 1V 2 inches (38 mm) of wood, or other 
approved covering or coating for a 1-hour rating. 



38 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



303.8 Penetrations. Through penetrations of fire-resis- 
tance-rated log wall assemblies shall comply with this section. 
All other penetrations shall comply with the applicable code. 

Exception: Where penetrating items are steel, ferrous or 
copper pipes or steel conduits, the annular space between 
the penetrating item and the fire-resistance-rated log wall 
assembly, the material used to fill the annular space shall 
prevent the passage of flame and gases sufficient to ignite 
cotton waste where subject to ASTM E 1 19 time-tempera- 
ture fire conditions under a minimum positive pressure dif- 
ferential of 0.01 inch (2.49 Pa) of water at the location of the 
penetration for the time period equivalent to the fire-resis- 
tance rating of the construction penetrated. 

303.8.1 Fire-resistance-rated assemblies. Penetrations 
shall be installed as tested in an approved fire-resis- 
tance-rated assembly. 

303.8.2 Through-penetration fireblocking system. 

Through penetrations shall be protected by an approved 
penetration fireblocking system installed as tested in accor- 
dance with ASTM E 8 14 or UL 1479, with a minimum posi- 
tive pressure differential of 0.01 inch (2.49 Pa) of water and 
shall have an F rating of not less than the required fire-resis- 
tance rating of the log wall assembly. 



SECTION 304 
PROVISIONS FOR SETTLING IN LOG STRUCTURES 

304.1 Settling. Provisions for settling in log structures shall be 
designed and constructed in accordance with the provisions of 
this section. 

304.2 Determining total settling. Total settling shall be deter- 
mined by the provisions of either Section 304.2.1, 304.2.2, 
304.2.3, 304.2.4 or 304.2.5. 

304.2.1 Prescriptive requirement: Total settling shall be 
equal to or greater than 6 percent of the involved height. 

304.2.2 Calculation procedure: Total settling shall be cal- 
culated using the following equation: 

At = A SL + Ac + As 

Where: 

A SL = Settling due to slumping. 

Ac = Settling due to compaction. 

As = Settling due to radial shrinkage. 

304.2.2.1 Settling due to slumping. Settling due to 
slumping (A SL ) shall be in accordance with the require- 
ments of this section. 

304.2.2.1.1 Prescribed slumping. Prescribed slump- 
ing shall be 3 f l6 inch (1.5 percent) per foot (4.8 mm per 
304 mm) of involved log wall height. 

304.2.2.1.2 Nonslumping conditions. A SL - when 
one of the following conditions exists. 

304.2.2.1.2.1 Continuous contact. Where Ac=0 
in accordance with Section 304.2.2.2.2. 



304.2.2.1.2.2 Coped wall systems. Settling due to 
slumping (A SI ) shall be permitted to be taken as 
when either Ac=0 or when MC D is less than or 
equal to MC S 

where: 

MC D - The design moisture content (see Section 
302.2.2.1). 

MC S = The service moisture content (see Section 
302.2.2.2). 

or when a seasoning kerf is cut opposite of the cope 
and all four of the following conditions are met: 

1. MC D >MC S 

where: 

MC D = The design moisture content (see Section 
302.2.2.1). 

MC S = The service moisture content (see Section 
302.2.2.2). 

2. The kerf depth shall be greater than or equal to 
0. 125 (V 8 ) times H L For tapered round logs, the 
kerf depth shall be greater than 0. 125 (7 8 ) times 
the diameter at all locations along the length of 
the log. In all conditions, kerf depth shall be less 
than HJ2. 

where: 

H L = The log stack height (see Section 
302.2.3.5). 

3. The wood separating the kerf from the cope 
shall be greater than or equal to the sum of the 
cope depth and the kerf depth. 

4. The cope depth shall be less than or equal to 
0.25 ('/ 4 ) times H L . 

where: 

H L = The log stack height (see Section 
302.2.3.5). 

304.2.2.1.2.3 Noncontact. Where logs are sepa- 
rated by bearing devices and joinery such that con- 
tact between logs is prevented. 

304.2.2.1.3 Calculating slumping. Settling due to 
slumping shall be calculated using the following for- 
mula: 



A SL = ** C A 



where: 



H rA xNxC Si 



CA - The height of the air space as measured from 
the apex of the cope to the top of the log 
beneath prior to installation. 

N = The number of longitudinal seams occurring 
within the involved height. 

C SL - The slumping coefficient = d/(p -W C -A ST ). 

where: 

d = The log diameter. 

p = The log circumference, pd - 3.141 6d. 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



39 



GENERAL REQUIREMENTS 



W c - The width of the cope, measured across the 
points of the cope 

A ST = Tangential shrinkage = [px(MC D 



-MCs)]/[(MC FSP xlOO/S - MC FSP ) + MC D ) 



where: 



MC D - The design moisture content (see Section 

302.2.2.3 and Section 302.2.2.1). 

MC S = The service moisture content (see Section 

302.2.2.4 and Section 302.2.2.2). 

MC FSP = Moisture content at fiber saturation point; 
see Table 304.2(1). Neither MC D nor MC S 
shall exceed MC FSP the moisture content 
value when shrinkage starts for most spe- 
cies. 

S = The shrinkage coefficient (%) in tangential 

(S T ) direction, see Table 304.2(2). 

C SL can be assumed to be 0.5 when p =0.375 d, 

MCD = MCFSP, 

MCS =12%, and S 7 =8%. 

304.2.2.2 Settling due to compaction. Settling due to 
compaction (Ac) shall be determined in accordance with 
the requirements of this section. 

304.2.2.2.1 Prescribed. Prescribed compaction shall 
be V 4 inch (6.4 mm) per log course or 2 percent of 
involved settling height. 

304.2.2.2.2 Noncompaction conditions. Ac = 
when B =B r . 

where: 

B r = Required bearing width. 

B = Actual bearing width of the log profile. 

304.2.2.2.2.1 Bearing width. The bearing width 
B, is the width of the horizontal contact area, 
between two wall logs, that is continuous for the 
full length of the logs. The required bearing width 
B r shall be calculated by the equation: 

5 r = [(W F +W R +W W )/12]/F C . 

where: 

W F = Total loading (plf) applied to the wall by 
floors above the starter log (sill log or bot- 
tom plate log). 

W R = Total loading (plf) applied to the wall by 
roofs above the starter log (sill log or bottom 
plate log). 

W w = Total weight the wall (plf) above the starter 
log (sill log or bottom plate log). 

f _ jh e allowable design value for compression 
perpendicular to grain (psi). 

304.2.2.2.2.2 Coped bearing surfaces. For 

angled or round bearing surfaces, divide the actual 



bearing width B, by the C AN factor in Table 304.2(3) 
to determine the required bearing width, B,, 

304.2.2.2.3 Compaction conditions. When logs are 
profiled with a cope on their underside, the weight of 
the log and imposed loads is transferred along the two 
lines of contact unless the cope is contoured to match 
the shape of the top of the log beneath (e.g., cope 
radius = log radius). 

304.2.2.3 Settling due to dimensional change. Settling 
of log walls due to shrinkage (dimensional change in 
cross-section, As) shall be determined in accordance 
with the provisions of this section. 

304.2.2.3.1 Prescribed, Method A. Prescribed 
shrinkage (As) shall be V 8 inch (3 percent) per foot 
(9.5 mm per 305 mm) of involved log wall height. 

304.2.2.3.2 Prescribed, Method B. Prescribed 
shrinkage (As) shall be 1 percent change in dimension 
per 4 percent change in moisture content (MC$-MC D ) 
per foot of involved log wall height. 

304.2.2.3.3 Prescribed, Method C. Select pre- 
scribed shrinkage (As) from Table 304.2(4) by cli- 
mate zone, initial moisture content (Mi), and 
shrinkage coefficient. Refer to the Climate Zone Map 
included in Figure 304.2.2.3 for a representation of 
geographic variation in outside equilibrium moisture 
content. 

304.2.2.3.4 Calculated. Settling due to shrinkage 
shall be calculated using the equation: 

As= [H D x(MC D -MC s )]/[(MC FSP xl00/S - 
MC FSP ) +MC D l 

where: 

H D - The height of the wall section (involved 
height); for horizontal joint design, H D = H L 
(see Section 302.2.3.5). 

MC D - The design moisture content (see Section 
302.2.2.1). 

MC S = The service moisture content (see Section 
302.2.2.2). 

MC FSP = Moisture content at fiber saturation point; 
see Table 304.2(1). Neither MC D nor MC S 
shall exceed MC FSP , the moisture content 
value where shrinkage starts for most spe- 
cies. 

S = The shrinkage coefficient (%) in radial (S R ) 

direction, see Table 304.2(2). 

304.2.3 Engineering analysis. Total settling is permitted to 
be determined by engineering analysis. 

304.2.4 Test method. Total settling is permitted to be deter- 
mined by using empirical test data. 

304.2.5 Field survey. Total settling is permitted to be deter- 
mined by using data reported from actual case studies from 



40 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



Marine (C) 




Ail of Alaska in Zone 7 
except for the following 
Boroughs in Zone 8: 

Bethel Northwest Arctic 

DeSSingham Southeast Fairbanks 

Fairbanks N. Star Wade Hampton 

Nome Yukon-Koyukuk 
North Slope 



FIGURE 304.2.2.3 
CLIMATE ZONE MAP 



an inventory of same construction with identical measure- 
ments taken yearly for a minimum of five years. 

304.3 Accommodating settling. Log structures shall accom- 
modate calculated settling. Calculated settling accommodation 
shall be stated in the construction documents for each location 
of involved settling height. 

Exception: Log wall systems where At is less than or equal 
to 0.5 percent of the involved settling height (H D ) to a maxi- 
mum of V 2 inch (12.7 mm). 

304.3.1 Settling gap. The settling gap must accommodate 
the involved settling height of materials as they settle. Trim 
or other measures used to conceal settling gaps in walls shall 
be treated as sliding joints. 

304.3.2 Sliding joint. Vertical joints shall not restrict set- 
tling at log wall interface. Examples include but are not lim- 
ited to the buck system installed at the sides of log wall 
openings, frame-wall intersections, cabinet installation, 
trim application, fireplaces and chimneys. 

304.3.3 Settling devices. An adjustable and accessible 
device shall be used to accommodate the involved settling 
height at point loads. Examples include and are not limited 
to support posts and horizontal structural framing member 
to non-settling structures. 



304.3.4 Staircases. Staircases shall be installed to accom- 
modate adjustment for settling between floor levels and/or 
landings. 

304.3.5 Counter-flashing. Counter-flashing shall be 
installed at all penetrations of the building exterior to allow 
appropriate movement due to settling. 

304.3.6 Fasteners/connections. Installation of fasteners 
and connections shall conform to the requirements of this 
section. 

304.3.6.1 Head of fasteners. Fasteners installed verti- 
cally shall be installed with the head a minimum of V 16 
inch (1.6 mm) below the surface of the log. Where 
exposed to the outside, the connection shall be protected 
to prevent the collection of moisture. 

304.3.6.2 Fasteners installed vertically. Where a fas- 
tener is installed vertically [plus or minus 5 degrees 
(0.0875 rad) from vertical] within the wall, it shall 
accommodate settling. 

Exception: Wall systems fastened in such a way that 
the fastening system holds each log at or close to its 
original elevation in the wall as the logs dry to equilib- 
rium moisture content. 

304.3.6.3 Fasteners installed horizontally. Fasteners 
installed horizontally through a log wall that attach 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



41 



GENERAL REQUIREMENTS 



non-settling abutments to the log wall shall be installed 
with an oversized washer under the head of the fastener 
and located near the top of an oversized vertically slotted 
hole such that the involved settling at that location is 
accommodated. The washer shall be able to turn under 
the fastener head. 

Exception: Wall systems fastened in such a way that 
the fastening system holds each log at or close to its 
original elevation in the wall as the logs dry to equilib- 
rium moisture, 

304.3.7 Electrical, mechanical, and plumbing systems. 

Installation of electrical, mechanical, and plumbing sys- 
tems shall conform to the requirements of this section. 

304.3.7.1 Flexible connections. Plumbing and 
ductwork running vertically through a floor, ceiling, or 
roof shall be equipped with flexible connections suffi- 
cient to accommodate the involved settling height. Wir- 
ing shall have sufficient slack or be provided with 
sufficient extra space to accommodate the involved set- 
tling height. 

304.3.7.2 Pipes through log walls. A plumbing pipe 
shall only travel through a log wall perpendicular to the 
long horizontal axis of the logs, shall be level or nearly 
level, and shall be fitted with flexible connections at each 
end or be provided with a sufficient settling gap to 
accommodate the involved setting height. 



SECTION 305 
THERMAL ENVELOPE 

305.1 Weather protection. Exterior walls shall comply with 
the applicable code and the provisions of this section. 

305.1.1 Joint design. Joint design and applied sealants shall 
be capable of maintaining the weather seal between logs in 
exterior walls as individual logs reach equilibrium moisture 
content. 

305.1.2 Moisture control and air leakage. The design 
shall resist air and moisture infiltration. 

305.1.3 Extreme conditions. Where the effects of wind due 
to exposure (Exposure C or D) or topography (wind 
speed-up effect) exist, the exterior joint design shall be cal- 
culated on the lower extent of the MC S range for the climate 
zone in accordance with Table 304.2.4. 

305.1.4 Kerfs. Kerfs shall be protected from weather by 
being fully covered by the joint pattern of the log above 
(e.g., cope, tongue and groove), or by a notch or sealant. 

305.1.5 Documentation. Assembly instructions for joints 
located on the exterior of a wall shall be detailed in the 
required construction documents. 

305.1.6 Sealant. Sealant materials shall be applied in accor- 
dance with sealant manufacturer recommendations, and 
instructions. Sealant materials shall be compatible with all 
materials in contact with the sealant. 

305.2 Procedural requirements. Compliance with the 
requirements of the International Energy Conservation Code 
or the energy provisions of the International Residential Code 



shall be determined in accordance with one of the following 
methods: 

1. Section 304.3.1 and International Energy Conservation 
Code Chapter 5, including Table 602.1.1.1(1), Mass 
Wall Prescriptive Building Envelope Requirements for 
Exterior or Integral Insulation. 

2. Energy compliance program. 

3. Performance basis using a certified energy rating sys- 
tem. 

305.3 Thermal properties of log walls. Thermal properties of 
log walls shall be determined in accordance with the methods 
provided in Section 305.3.1, 305.3.2 or 305.3.3. 

305.3.1 Prescribed method. The R-value of the opaque log 
wall assembly shall be selected from Table 305.3.1. 

305.3.2 Test method. Physical testing of thermal conduc- 
tance shall be in accordance with ASTM C 177, ASTM C 
236, orASTMC518. 

305.3.3 Calculation method. Calculate the Coefficient of 
Transmission (u) of the log wall using the equation: 

U = 1 /(inside air film + Ro + outside air film) 

where: 

Inside Air Film = An 7?-value of 0.68 for still air at a verti- 
cal surface and horizontal heat flow. 

Outside Air Film = An tf-value of 0.17 for a 15 mph (6.6 
m/s) wind moving air in any direction 
during the winter. 

Ro = [(A L x R L ) + (A N x R N )]/A T = The overall /?- value of 
the wall assembly found by weighted average of 
areas of the assembly for respective variations in the 
cross-section of the wall. If the entire wall assembly 
consists only of logs, Ro = R L . 

where: 

A L = L T x (IR h Q/H = The percentage of the wall that 
consists of log. 

A N = L T x (H N C) I H - The percentage of the wall that is 
other than log. 

where: 

L T - The length of a wall using the dimension for the inte- 
rior face of exposed wall. 

lR h - The height of the inscribed rectangle. 

H N - The height of the cross-section that is not log. 

C = The number of courses that constitute the vertical 
wall dimension. 

H = The overall height of the finished wall. 

A T - The total wall area. 

R L = w L /k 

where: 

W L - The average thickness of the log at time of manufac- 
ture. 

k = Btu-in/(h-ft 2 -F) = G[B+C (MQ] + A 



42 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



GENERAL REQUIREMENTS 



TABLE 305.3.1 
LVALUE OF LOG WALL (RJBY AVERAGE WIDTH (W L ) AND SPECIFIC GRAVITY 



> 
O 



o 
<u 
a 
(f) 





Average 


Width 


















5 in. 


6 in. 


7 in. 


8 in. 


9 in. 


10 in. 


12 in. 


14 in. 


16 in. 


0.29 


8.98 


10.61 


12.23 


13.86 


15.48 


17.11 


20.36 


23.61 


26.86 


0.3 


8.76 


10.35 


11.93 


13.51 


15.1 


16.68 


19.84 


23.01 


26.17 


0.31 


8.56 


10.1 


11.64 


13.19 


14.73 


16.27 


19.35 


22.44 


25.52 


0.32 


8.37 


9.87 


11.37 


12.87 


14.38 


15.88 


18.89 


21.89 


24.9 


0.33 


8.18 


9.65 


11.11 


12.58 


14.04 


15.51 


18.44 


21.38 


24.31 


0.34 


8 


9.44 


10.87 


12.3 


13.73 


15.16 


18.02 


20.88 


23.75 


0.35 


7.84 


9.23 


10.63 


12.03 


13.43 


14.82 


17.62 


20.41 


23.21 


0.36 


7.68 


9.04 


10.41 


11.77 


13.14 


14.5 


37.24 


19.97 


22.7 


0.38 


738 


8.68 


9.99 


11.3 


12.6 


13.91 


16.52 


19.13 


21.74 


0.39 


7.24 


8.52 


9.79 


11.07 


12.35 


13.63 


16.18 


18.74 


21.29 


0.41 


6.98 


8.2 


9.43 


10.65 


11.88 


13.1 


15.55 


18 


20.45 


0.42 


6.85 


8.05 


9.25 


10.45 


11.66 


12.86 


15.26 


17.66 


20.06 


0.44 


6.62 


7.77 


8.93 


10.08 


11.24 


12.39 


14.7 


17.01 


19.32 


0.47 


6.3 


7.4 


8.49 


9.58 


10.67 


11.76 


13.94 


16.12 


18.3 


0.5 


6.02 


7.05 


8.09 


9.12 


10.16 


11.19 


13.26 


15.33 


17.4 


0.51 


5.93 


6.95 


7.97 


8.98 


10 


11.02 


13.05 


15.08 


17.11 


0.52 


5.85 


6.85 


7.85 


8.85 


9.85 


10.84 


12.84 


14.84 


16.84 


0.53 


5.77 


6.75 


7.73 


8.71 


9.7 


10.68 


12.65 


14.61 


16.58 


0.54 


5.69 


6.65 


7.62 


8.59 


9.55 


10.52 


12.45 


14.39 


16.32 


0.55 


5.61 


6.56 


7.51 


8.46 


9.41 


10.37 


12.27 


14.17 


16.08 


0.59 


5.32 


6.22 


7.11 


8.01 


8.9 


9.8 


11.58 


13.37 


15.16 


0.6 


5.26 


6.14 


7.02 


7.9 


8.78 


9.66 


11.43 


13.19 


14.95 


0.7 


4.69 


5.46 


6.23 


6.99 


7.76 


8.53 


10.07 


11.6 


13.14 



For SI: 1 inch - 25.4 mm. 
Notes to Table 305.3. 1: 

1 . The tabulated values assume MC S to be at 12 percent. 

2. Above and left of the bold line, log criteria does not meetlECC requirements for heat capacity for thermal mass credit. 

3. The tabulated lvalues represent walls with log-to-log contact at all seams inclusive of air films. The u-value, required in energy conservation calculations, is the 
inverse of the R- value. 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



43 



GENERAL REQUIREMENTS 



G = Specific gravity. 

MC S = The service moisture content. 

A = 0.129, B = 1.34, and C = 0.028; the constants A, B, 
and C represent specific gravity greater than 0.30, 
design temperature at 75°F, (17°C) and moisture 
content less than 25 percent. 

R N = The sum of the R- values of the components that con- 
stitute the nonwood cross-section of the wall. 

305.4 Thermal mass effect of log walls. Log walls having a 
mass greater than or equal to 20 lb/ft 2 (98 kg/m 2 ) of exterior 
wall area shall be deemed to have heat capacities equal to or 
exceeding 6 Btu/ft 2 [KJ(m 2 +K)] The thermal mass benefit of 
log walls shall be determined in accordance with this section. 

305.4.1 Establishing thermal mass. Thermal Mass shall 
be established using one of the methods described in the fol- 
lowing sections. 

305.4.1.1 Prescribed method. The thermal mass of the 
opaque log wall assembly shall be established from 
Table 305.3.1. 

305.4.1.2 Test method. Physical testing of the thermal 
mass shall be in accordance with ASTM C 976. 

305.4.1.3 Calculation method. Either calculate the 
weight of the wall in pounds per square foot (psf) using 
the density equation in Section 302.2.3.7 or determine 
the heat capacity for the thermal mass provision using the 
following. 

HC= wxc 

where: 

HC = Heat capacity of the exterior wall, Btu/ft 2 x°F 
[kJ/(m 2 xK)] of exterior wall area. 

w = Mass of the exterior wall, lb/ft 2 (kg/m 2 ) of exte- 
rior wall area is the density of the exterior wall 
material, lb/ft 3 (kg/m 3 ) multiplied by the thick- 
ness of the exterior wall calculated in accordance 
with section 302.2.3.6. 

c - Specific heat of the exterior wall material, 
Btu/lbx°F [kJ/(kgxK)] of exterior wall area as 
determined from Table 305.4.1.3. The moisture 



content references in Table 305.4.1.3 shall be 
selected to be less than or equal to MC S . 

305.4.2 Applying the thermal mass effect. When the wall 
assembly is determined to have sufficient thermal mass, the 
wall shall be deemed to comply with the code and is permit- 
ted to be further evaluated as a mass wall with integral insu- 
lation. 

305.4.2.1 Determine the required U w . Using the gross 
wall calculation and the required {/-values in accordance 
with the International Energy Conservation Code, deter- 
mine the required {/-value for the opaque wall area using 
the equation: 



U w = (A^xJIJl 



KiioJiA £ }±ai d ^A d ii 



where: 



JJ W - The thermal transmittance value for the compli- 
ant insulated frame wall. 



4,= 


Gross wall area. 


u 


The allowable overall U for the gross wall 


A g = 


Window area. 


u* = 


The actual value for windows. 


A d = 


Door area. 


u d = 


The actual value for doors. 


K = 


The area of the opaque wall. 



Where there are more than one door or window in the 
wall, the equation shall sum the UA for each window and 
door. 

305.4.2.2 Determine the mass U w . Referring to IECC 
Table 502.2.1.1.2(3), select the column by matching the 
U w determined in Section 305.4.2.1 to those heading the 
columns. Select the row according to the design heating 
degree days. Where the column and row cross provides 
the U w with thermal mass effect. 







TABLE 305.4.1.3 
HEAT CAPACITY OF SOLID WOOD 








Temperature 






Specific heat [(kJ/kg»K(Btu/lb*°F))] 




(K) 


°C 


op 


Ovendry 


5%MC 


12% MC 


20% MC 


280 


7 


45 


1.2(0.28) 


1.3(0.32) 


1.5(0.37) 


1.7(0.41) 


290 


17 


75 


1.2(0.29) 


1.4(0.33) 


1.6(0.38) 


1.8(0.43) 


300 


27 


80 


1.3(0.30) 


1.4(0.34) 


1.7(0.40) 


1.9(0.45) 


320 


47 


116 


1.3(0.32) 


1.5(0.37) 


1.8(0.43) 


2.0 (0.49) 


340 


67 


152 


1.4(0.34) 


1.6(0.39) 


1.9(0.46) 


2.2 (0.52) 


360 


87 


188 


1.5(0.36) 


1.7(0.41) 


2.0 (0.49) 


2.3 (0.56) 



44 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



CHAPTER 4 

STRUCTURAL PROVISIONS 



SECTION 401 
GENERAL 

401.1 General. The structural design of log structures shall 
comply with the general requirements of this chapter. 

401.2 Structural provisions. The provisions of this Chapter 
provide minimum load, resistance and prescriptive require- 
ments for structures within the scope of this document. The 
information does not represent a complete engineering analy- 
sis. All log structures shall meet the requirements of Section 
401 and further comply with the prescriptive provisions of Sec- 
tion 402 or the engineered provisions of Section 403, or a com- 
bination thereof. 

401.3 General provisions. General provisions for the design 
of log structures shall be in accordance with provisions of this 
section and Chapter 3. 

401.4 Continuous load path. A continuous load path shall be 
provided to transfer all lateral and vertical loads from the roof, 
wall, and floor systems to the foundation. 

401.5 Interpolation. Interpolation of tabulated values in this 
chapter shall be permitted unless otherwise noted in the appli- 
cable table footnotes. 



SECTION 402 
PRESCRIPTIVE PROVISIONS 

402.1 Prescriptive provisions. Log structures not requiring 
engineering design in accordance with Section 403 shall be 
permitted to use prescriptive provisions as approved by the 
building official. 



SECTION 403 
ENGINEERED PROVISIONS 

403.1 Applicability. If the building geometry, or loads related 
to the log structure, exceed any of the following limitations, 
then the building shall be designed using the provisions of 
Sections 403 through 407. If portions of building geometry, or 
loads related to those portions, exceed any of the following lim- 
itations, then the affected portions shall be designed using the 
provisions of Sections 403 through 407. The limitations are: 

1. Loads: 

a. Greater than 40-psf (1916 N/m 2 ) live load on floors. 

b. Greater than 70-psf (3353 N/m 2 ) ground snow load. 

c. Greater than 90 mph (39.6 m/s) wind speed (3 second 
gust). 

d. Greater than Wind Exposure Category B. 

e. Greater than Seismic Design Category B. 



Exception: Detached one- and two-family dwell- 
ings located in Seismic Design Category C. 

2. Building dimensions 

a. Greater than three stories or a mean roof height of 33 
feet, (100.6 m) measured from average grade to aver- 
age roof elevation. 

b. The building aspect ratio (LAV) less than 1:4 or 
greater than 4:1. 

c. The building dimension, length (L) or width (W), 
greater than 80 feet (243.8 m). 

d. Floor to floor story height greater than 10 feet (3.0 m) 

3. Log floor systems 

a. Single spans of log floor framing members greater 
than 26 feet (79.2 m). 

b. Spacing of logs used as floor framing members 
greater than 48 inches (1219 mm) on center. 

c. Cantilever lengths of logs used as cantilevered floor 
framing members supporting load bearing walls or 
shear walls greater than the depth, d, of the log joists. 

d. Log floor joist cantilevers supporting nonload-bear- 
ing walls which are not shear walls greater than 
one-quarter of the span, L/4. 

e. Setbacks of load bearing walls or shear walls on log 
floor joist systems greater than the depth, d, of the log 
joists. Log floor joists shall be located directly over 
structural elements when used in setback conditions 
supporting load bearing walls. 

f. Vertical log floor offsets greater than the log floor 
depth, (including log floor framing members and 
floor sheathing). 

g. Log floor diaphragm aspect ratios greater than limits 
from Table 403.1. 

h. Log floor diaphragm openings greater than 12 feet 
(36.6 m) or 50 percent of the building, whichever is 
less. 

4. Log walls 

a. Load bearing and nonload-bearing log walls greater 
than 20 feet (61 m) in unsupported height. 

b. Offsets in a log shear wall line within a story greater 
than 4 feet (1219 m). 

c. Upper story log shear wall segments offset from 
lower story log shear wall segments by more than the 
depth, d, of the log floor framing members. 

d. Log shear wall segment aspect ratios greater than 1:1. 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



45 



STRUCTURAL PROVISIONS 



e. Log shear wall lines oriented to resist loads in two 
orthogonal directions. 

5. Log roof systems 

a. Single spans (horizontal projection) of log roof fram- 
ing members greater than 26 feet (79.2 m). 

b. Roof framing member spacing greater than 48 inches 
on center. 

c. Log rafter overhang lengths greater than one-third of 
the rafter span or 4 feet (1219 mm), whichever is less. 
Rake overhangs greater than one-half of the purlin 
length or 4 feet (1219 mm), whichever is less. 

d. Roof slope greater than 12:12. For purposes of deter- 
mining uplift, gravity loads, and lateral bracing 
requirements, the attic shall be considered an addi- 
tional story when the roof slope is 7:12 or greater. 

e. Roof diaphragm aspect ratios greater than values 
from Table 403.1. 

TABLE 403.1 

MAXIMUM DIAPHRAGM ASPECT RATIOS (HORIZONTAL 

OR SLOPED DIAPHRAGMS) 



Diaphragm 


Maximum 


Sheathing Type 


L/W Ratio 


Wood structural panel, 
unblocked 


3:1 


Wood structural panel, blocked 


4:1 


Single-layer straight lumber 
sheathing 


2:1 


Single-layer diagonal lumber 
sheathing 


3:1 


Double-layer diagonal lumber 
sheathing 


4:1 



403.2 Design methodology. Log structures shall be designed 
using allowable stress design or load and resistance factor 
design as follows: 

403.2.1 Allowable stress design. Allowable stress design 
of wood structural components shall be in accordance with 
AFPA NDS. 

Exception: Log structures intended for one- and 
two-family dwellings shall be permitted to be designed 
in accordance with the applicable provisions of 
AF&PAs WFCM. 

403.2.2 Load and resistance factor design. Load and 
resistance factor design of wood structural components 
shall be in accordance with AFPA NDS. 

403.3 Design values. Design values shall be in accordance 
with Section 302.2.3. 

403.4 Design capacities. When design capacities are required, 
the design values shall be multiplied by the section properties 
from Section 302.2.3.4 as follows: 

Apparent Rigidity = E 7 



Moment 


M r = F' b S 


Shear 


V r = F\ Ib/Q 


Bearing 


B = F' C ±A 


Tension 


T=F\A 


Compression 


P = F\A 



403.5 Combined loads. Combined bending and axial load 
conditions shall be designed in accordance with the AF&PA 
NDS. 



SECTION 404 
CONNECTIONS 

404.1 Lateral connections. Connections between roof, ceil- 
ing, wall, and floor assemblies shall be designed to transfer lat- 
eral forces acting perpendicular to the wall surface. 

Connections to transfer lateral loads from the foundation 
wall into the floor diaphragm assembly shall be in accordance 
with the foundation design. 

404.2 Shear connections. Connections between roof, ceiling, 
wall, and floor assemblies shall be designed to transfer shear 
forces due to wind and seismic loads, acting parallel to the wall 
surface. 

404.2.1 Roof, ceiling, or floor assembly to wall assembly. 

Connections shall be designed to transfer shear loads from 
the roof, ceiling, or floor diaphragm assembly to the shear 
wall segments. 

404.2.2 Wall assembly to wall assembly. Connections 
shall be designed to transfer shear loads from a shear wall 
segment above to a shear wall segment below. 

404.2.3 Floor assembly to foundation. Connections shall 
be designed to transfer shear loads from the floor assembly 
to the foundation. 

404.2.4 Wall assembly to foundation. Connections shall 
be designed to transfer shear loads from the wall assembly 
to the foundation. 

404.3 Uplift connections. Connections shall be designed to 
resist uplift forces. 

404.4 Overturning resistance. Resistance to overturning shall 
be provided. Hold downs to provide overturning restraint to 
shear wall segments at each level shall be provided at the ends 
of shear walls and as required to develop the shear capacity of 
the wall segments in accordance with Section 406. 1. A contin- 
uous load path from the hold down to the foundation shall be 
maintained. Where a hold down resists the overturning load 
from the story or stories above, the hold down shall be sized for 
the required hold down tension capacity at its level plus the 
required hold down tension capacity of the story or stories 
above. Hold downs used to resist both uplift and overturning 
shall be designed to resist the sum of the forces determined in 
accordance with Section 404.3 and this section. 

404.5 Sheathing and cladding attachment. Attachment of 
sheathing and cladding shall be designed to transfer specified 
loads into framing members. 



46 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



STRUCTURAL PROVISIONS 



404.5.1 Roof sheathing. Roof sheathing shall be designed 
and attached to roof structural members to resist the calcu- 
lated withdrawal loads (suction) and provide the roof dia- 
phragm shear capacity required in Section 407.14. 

404.5.2 Floor sheathing. Floor sheathing shall be designed 
and attached to provide the floor diaphragm shear capacity 
required in Section 405.10. 

404.6 Special connections. Consideration shall be given to 
special connections as addressed in this section. 

404.6.1 Ridge connections. Connections at the roof ridge 
shall be designed to resist the calculated loads. 

404.6.2 Log jack rafters. Connection of the log jack rafter 
to the log wall shall be designed in accordance with Section 

404.3. Connection of the log jack rafter to log hip beam or 
log valley beam shall be designed to resist the calculated 
loads. 

404.6.3 Log hip and log valley beams. Log hip and log val- 
ley beams do not require special uplift connections when 
log jack rafters are attached in accordance with Section 
403.6.6.2. 

404.6.4 Uplift loads on exterior log wall assemblies. Log 

walls that support log rake overhang outlookers or lookout 
blocks shall be designed to resist the uplift loads. Log walls 
that do not support the roof assembly need only resist the 
uplift load. 

404.6.5 Log wall openings. Connections to transfer lateral, 
shear, and uplift loads around log wall openings shall be in 
accordance with the loads specified in Sections 406. 1, 

406.4, and 406.5. A continuous load path shall be main- 
tained around the opening. 

404.6.6 Thrust connection. Connections to transfer thrust 
loads in the lower third of the attic space shall be designed to 
resist the calculated thrust loads. 

404.6.7 Log rake overhang outlookers. Connections of 
log rake overhang outlookers to the gable end wall shall be 
designed to resist the calculated uplift loads. 



SECTION 405 
FLOOR SYSTEMS 

405.1 Log framing members. Single span, continuous span, 
and cantilevered log framing members shall be designed to 
resist the calculated loads. 

405.2 Framing spans. Design of log framing members shall 
consider both strength and serviceability limits. For service- 
ability, the computed log floor joist deflection under live load 
shall not exceed the deflection limits in the applicable code. For 
simple, continuous and cantilevered bending members, the 
span shall be taken as the distance from face to face of supports, 
plus ¥2 the required bearing length at each end. 

405.3 Framing member spacing. Logs used as floor framing 
members shall be spaced according to the design requirements. 

405.4 Bearing. Framing members shall bear directly on 
beams, girders, ledgers, or load bearing walls or be supported 
by hangers or framing anchors. Framing members shall be 



designed to resist the calculated bearing loads. Minimum bear- 
ing area shall be based on consideration of both the framing 
member and supporting member. 

405.5 Single or continuous log floor joists supporting load 
bearing walls. Load bearing log walls parallel to log joists 
shall be supported directly by beams, girders, or other load 
bearing walls. Log joists supporting load bearing log walls that 
are perpendicular to the joists shall be designed to carry the 
additional gravity load. 

405.6 Single or continuous log floor joists supporting 
non-load bearing walls. Where nonload-bearing log walls are 
parallel or perpendicular to log floor joists, the joist(s) and 
sheathing supporting the nonload-bearing wall shall be 
designed to carry the additional weight of the wall. 

405.7 Cantilevered log floor joists supporting walls. Over- 
hang lengths of cantilevered log floor joists supporting a wall at 
the end of the cantilever shall be designed for the cantilevered 
condition with the additional floor load of the cantilevered area 
and the gravity load of the wall specified. 

405.8 Floor openings. Framing around floor openings shall be 
designed to transfer loads to adjacent framing members that are 
designed to support the additional concentrated loads. Fasten- 
ers, connections, and stiffeners shall be designed for the load- 
ing conditions. Where the edge of the opening is less than 2 feet 
(610 mm) from an exterior wall, the exterior wall adjacent to 
the opening shall be designed to resist gravity, lateral, and 
uplift loads at that location. 

405.9 Sheathing and decking spans. Floors shall be fully 
sheathed with materials capable of resisting and transferring 
the applied gravity loads to the floor framing members. 

405.10 Diaphragm capacity. Floor sheathing and fasteners 
shall be capable of resisting the total calculated shear loads for 
wind or seismic motion perpendicular to the ridge and parallel 
to the ridge. Diaphragm chords shall be continuous for the full 
length of the diaphragm. Diaphragm chords and chord splices 
shall be capable of resisting the chord forces, calculated by the 
following equation: 

T= vU4 

where: 

T- Chord force, lbs. 

v = Required unit shear capacity of the floor diaphragm, plf 

L = Floor diaphragm dimension perpendicular to the lateral 
load, ft. 

405.11 Floor diaphragm bracing. Framing and connections 
shall be designed, to transfer the lateral wind loads from the 
exterior wall to the floor diaphragm assembly in accordance 
with the calculated loads. 



SECTION 406 
LOG WALLS 

406.1 Load resistance. Log walls shall be designed to resist 
wind and seismic loads, gravity loads and uplift loads in accor- 
dance with applicable load standards. The maximum shear 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



47 



STRUCTURAL PROVISIONS 



wall aspect ratio shall be 1:1 for walls used in the design as 
shear walls to resist wind and seismic loads. 

406.2 Corners and intersecting log walls. Log walls shall be 
connected by mechanical fastening or interlocking joinery at 
corners, and intersecting walls and beams to resist and transfer 
lateral loads to the roof or floor diaphragm. Wall logs shall be 
continuous within a single course between openings, or have 
designed fastening at splices between logs to resist lateral load- 
ing. 

406.3 Log bottom plate to foundation. Log bottom plates 
shall be connected to transfer lateral loads to the floor dia- 
phragm. Sill logs shall be connected to transfer lateral loads to 
the foundation. 

406.4 Header logs. Header logs shall be provided over all log 
wall openings to resist lateral and gravity loads. Header logs 
shall be continuous over and beyond the wall opening to pro- 
vide connection to the wall assembly and bearing area such that 
the load imposed by the header will be distributed over the sup- 
porting logs. 

406.5 Window sill log. Window sill logs shall be designed to 
resist lateral loads. Window sill logs shall extend beyond the 
edge of the window opening to provide connection to the wall 
assembly. 

406.6 Interior nonload-bearing log partitions. Interior 
nonload-bearing log partitions shall be designed to support 
their self-weight. Foundations or other supporting elements 
shall also be designed for the dead weight of the log partition. 



SECTION 407 
ROOF SYSTEMS 

407.1 Framing spans. Log framing members shall be evalu- 
ated for both strength and serviceability limits. For serviceabil- 
ity, the computed log rafter deflection under live load shall not 
exceed the deflection limitations listed in the applicable code. 
For simple, continuous and cantilevered bending members, the 
span shall be taken as the distance from face to face of supports, 
plus V 2 the required bearing length at each end. 

407.2 Framing spacing. Logs used as framing members shall 
be spaced according to the design requirements. 

407.3 Slope. Roof slope shall be used to calculate vertical and 
lateral loads on the structure. 

407.4 Log jack rafters. Log jack rafters shall be in accordance 
with Section 404.6.2. 

407.5 Log rafter overhangs. Log rafter overhang lengths shall 
be designed to resist calculated loads. 

407.6 Rake overhangs. Log rake overhang outlookers shall 
use continuous purlins connected in accordance with Section 
404.6.7. 

407.7 Bearing. Framing members shall bear directly on 
beams, girders, ledgers, posts or load-bearing walls or be sup- 
ported by hangers or framing anchors. Framing members and 
supports shall be designed to resist the calculated bearing 
loads. Minimum bearing area shall be based on consideration 
of both the framing member and supporting member. 



407.8 Ridge beams. Log rafters shall be supported on bearing 
walls, headers, purlins and/or ridge beams. When ridge beams 
support log rafters, beams shall be in accordance with the cal- 
culated capacity requirements. Log rafters shall bear directly 
on the ridge beam or be supported by hangers or framing 
anchors. Ceiling joists or rafter ties shall not be required to 
resist horizontal thrust where a ridge beam is provided. 

407.9 Hip and valley log beams. Hip and valley log beams 
shall be designed to resist the calculated loads. 

407.10 Log ceiling joists. Log ceiling joists shall be designed 
to resist the calculated loads, including bending and tension. 

407.11 Open ceilings. Where ceiling joists and roof ties are 
omitted and log rafters are used to create an open (cathedral) 
ceiling, log rafter ends shall be supported on bearing walls, 
headers, purlins or ridge beams. Log rafters shall be attached to 
the support at each end in accordance with Section 404.6.6. 

407.12 Roof openings. Framing around roof openings shall be 
designed to transfer loads to adjacent framing members that are 
designed to support the additional concentrated loads. Fasten- 
ers and connections, shall be designed for the loading condi- 
tions. 

407.13 Sheathing and decking spans. Roofs shall be sheathed 
sheathing materials capable of resisting and transferring the 
applied gravity loads and wind loads to the roof framing mem- 
bers. 

407.14 Diaphragm capacity. Roof sheathing and fasteners 
shall be capable of resisting the total shear loads calculated for 
wind or seismic motion perpendicular or parallel to the ridge. 
Diaphragm chords shall be continuous for the full length of the 
diaphragm. Diaphragm chords and chord splices shall be capa- 
ble of resisting the chord forces, calculated by the following 
equation: 

T= vU4 

where: 

T = Chord force, lbs. 

v = Required unit shear capacity of the roof diaphragm, plf 

L - Roof diaphragm dimension perpendicular to the lateral 
load, ft. 

407.15 Roof diaphragm bracing. Framing and connections 
shall be designed, to transfer the lateral wind loads from the 
exterior wall to the roof diaphragm assembly in accordance 
with the calculated loads. 



48 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



CHAPTER 5 

REFERENCED STANDARDS 



This chapter lists the standards that are referenced in various sections of this document. The standards are listed herein by the pro- 
mulgating agency of the standard, the standard identification, the effective date and title, and the section or sections of this document 
that reference the standard. The application of the referenced standards shall be as specified in Section 109.1. 



AF&PA 



American Forest & Paper Association 
1111 19th Street, NW Suite 800 
Washington, DC 20036 



Standard 
reference 
number 



Title 



AFPA NDS-05 



WFCM-01 



National Design Specification® (AFPA NDS) for Wood Construction 

with 2005 Supplement 108, 302.2.3.1, 302.2.3.3.2, 302.2.4.8, 302.3, 303.2.2, 403.2.2 

Wood Frame Construction Manual for One- and Two-Family Dwellings 403.2.1 



ASME 



American Society of Mechanical Engineers 

Three Park Avenue 

New York, NY 100116-5990 



Standard 
reference 
number 



Title 



B18. 2.1-96 
B18.6.1-81 



Square and Hex Bolts and Screws (Inch Series) . 
Wood Screws (Inch Series) 



.302.3.1 
.302.3.4 



ASTM 



ASTM International 

100 Bar Harbor Drive 

West Conshohocken, PA 19428-2959 



Standard 
reference 
number 



Title 



A 653/ A 653M-02a 
with the 2004 Supplement 

A 653/A 653M-04a 

C 177-97 
C236-89(1993)el 

C518-02el 
C 976-90 
D245-00(2002)el 

D 2395 

D2555-98el 

D3737-01b 

D 3957-03 

D 4933-99 (2004) 

E 119-00a 

E814 

E 1966-01 

F 1667-02a 



Standard Specification for Steel Sheet, Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by 
the Hot-Dip Process 302.3.5 

Specification for Sheet Steel, Zinc-coated Galvanized or Zinc-iron Alloy-coated, Galvannealed 
by the Hot-dip Process 302.3.5 

Guarded Hot Plate 305.3.2 

Standard Test Method for Steady-State Thermal Performance of Building Assemblies by Means of a 

Guarded Hot Box 305.3.2 

Heat Flow Meter 305.3.2 

Calibrated Hot Box (to determine thermal mass) 305.4.1 .2 

Standard Practice for Establishing Structural Grades and Related Allowable Properties for 

Visually Graded Lumber 202, 302.2.1.1, 302.3.3.1 

Standard Test Methods for Specific Gravity of Wood and Wood Based Material 302.2.3,3.4 

Standard Test Methods for Establishing Clear Wood Strength Values 302.2.1.2, 302.3.3.3, Table 302.2(1) 

Standard Practice for Establishing Stresses for Structural Glued Laminated Timber (Glulam) 202, 302.2.1.1 

Standard Practice for Establishing Stress Grades for Structural Members Used in Log Buildings 202, 302.2.1.1 

Standard Guide for Moisture Conditioning of Wood and Wood-Based Materials 302.2.2.2 

Standard Test Methods for Fire Tests of Building Construction and Materials 303.2.3 

Test Method of Fire Tests of Through-penetration Firestops 303.8.2 

Standard Test Method for Fire-Resistive loint Systems 303.5, 303.8 

Standard Specification for Driven Fasteners; Nails, Spikes, and Staples (2004 Supplement) 302.3.3 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



49 



REFERENCED STANDARDS 



ICC 



International Code Council 

500 New Jersey Avenue, NW 6 ,h Floor 

Washington, D.C. VA 20001 



Standard 
reference 
number Title 



IBC-06 International Building Code® 103.1, 107.1, 108.2 

IRC-06 International Residential Code® 103.1, 107.1, 305.2 

1ECC-03 International Energy Conservation Code® 305.2, Table 305.3.1, 305.4.2.1 



UL 



Underwriters Laboratories, Inc. 
333 Pfingston Road 
Northbrook, IL 60062 



Standard 
reference 
number Title 



UL 1479 Fire Tests of Through-Penetration Firestops 303.8.2 

UL 2079-98 Tests For Fire Resistance of Building Joint Systems 303.5 



50 STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 



EDITORIAL CHANGES - SECOND PRINTING 

Page 36, Table 304.2(2) - All Coefficients moved down one row throughout the table. 

Page 42, 305.3.3: formula for k now reads . . . k = Btu~in/(h~fr F) = G [fl+ C (MC S )] + A 

EDITORIAL CHANGES - THIRD PRINTING 

Page 44, 305.4.1.1: Last line now reads . . . Table 305.3.1. 

Page 50, ICC, IECC-06 entry now reads . . . IECC-03, International Energy Conservation Code®, 305.2, Table 305.3.1, 
305.4.2.1. 



STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES 51 



52 STANDARD ON THE DESIGN AND CONSTRUCTION OF LOG STRUCTURES