NDS ® Supplement National Design Specification® Design Values for Wood Construction 2015 EDITION November 2014 Updates and Errata While every precaution has been taken to ensure the accuracy of this document, errors may have occurred during development. Updates or Errata are posted to the American Wood Council website at www.awc.org. Technical inquiries may be addressed to [email protected]. The American Wood Council (AWC) is the voice of North American traditional and engineered wood products. From a renewable resource that absorbs and sequesters carbon, the wood products industry makes products that are essential to everyday life. AWC’s engineers, technologists, scientists, and building code experts develop state-of-the-art engineering data, technology, and standards on structural wood products for use by design professionals, building officials, and wood products manufacturers to assure the safe and efficient design and use of wood structural components. Copyright © American Wood Council. Downloaded/printed pursuant to License Agreement. No reproduction or transfer authorized. ® NDS Supplement National Design Specification® Design Values for Wood Construction 2015 EDITION Copyright © 2014 American Wood Council November 2014 ii DESIGN VALUES FOR WOOD CONSTRUCTION – NDS SUPPLEMENT National Design Specification (NDS) Supplement: Design Values for Wood Construction 2015 Edition First Web Version: November 2014 ISBN 978-1-940383-06-4 Copyright © 2014 by American Wood Council All rights reserved. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including, without limitation, electronic, optical, or mechanical means (by way of example and not limitation, photocopying, or recording by or in an information storage retrieval system) without express written permission of the American Wood Council. For information on permission to copy material, please contact: Copyright Permission American Wood Council 222 Catoctin Circle, SE, Suite 201 Leesburg, VA 20175 [email protected] Copyright © American Wood Council. Downloaded/printed pursuant to License Agreement. No reproduction or transfer authorized. AMERICAN WOOD COUNCIL DESIGN VALUES FOR WOOD CONSTRUCTION – NDS SUPPLEMENT iii Introduction This Supplement is a compendium of reference de- for conformance to established certification and quality sign values for structural sawn lumber, structural glued control procedures. laminated timber, and round timber piles and poles. These For additional information on development and appli- reference design values have been obtained from the or- cability of lumber reference design values, grading rules ganizations responsible for establishing design values for published by individual agencies and referenced ASTM these products. Reference design values in this Supple- Standards should be consulted. ment are provided as a courtesy for use with the design Structural Glued Laminated Timber provisions of the National Design Specification® (NDS®) Reference design values in this Supplement for struc- for Wood Construction, 2015 Edition. tural glued laminated timber are developed and published Lumber by the American Institute of Timber Construction (AITC) Reference design values for lumber in this Supple- and APA–The Engineered Wood Association (APA) in ment are obtained from grading rules published by seven accordance with principles originally established by the agencies: National Lumber Grades Authority (a Canadian U.S. Forest Products Laboratory in the early 1950s. These agency), Northeastern Lumber Manufacturers Association, principles involve adjusting strength properties of clear Northern Softwood Lumber Bureau, Redwood Inspection straight grained lumber to account for knots, slope of grain, Service, Southern Pine Inspection Bureau, West Coast density, size of member, number of laminations, and other Lumber Inspection Bureau, and Western Wood Products factors unique to laminated timber. Association. Grading rules promulgated by these agencies, Specific methods used to establish reference design including reference design values therein, have been ap- values have been periodically revised and improved to proved by the Board of Review of the American Lumber reflect results of tests of large structural glued laminated Standard Committee and certified for conformance with timber members conducted by the U.S. Forest Products U.S. Department of Commerce Voluntary Product Stan- Laboratory and other accredited testing agencies. The dard PS 20-10 (American Softwood Lumber Standard). performance history of structures made with structural Reference design values for most species and grades of glued laminated timber conforming to AITC or APA speci- visually graded dimension lumber are based on provisions fications and manufactured in accordance with American of ASTM Standard D 1990-14 (Establishing Allowable National Standard ANSI A190.1-2012 (Structural Glued Properties for Visually Graded Dimension Lumber from Laminated Timber) has demonstrated the validity of meth- In-Grade Tests of Full-Size Specimens). Reference design ods used to establish structural glued laminated timber values for visually graded timbers, decking, and some reference design values. species and grades of dimension lumber are based on pro- Round Timber Piles and Poles visions of ASTM Standard D 245-06 (2011) (Establishing Reference design values in this Supplement for round Structural Grades and Related Allowable Properties for timber piles and poles are developed by the Timber Piling Visually Graded Lumber). Methods in ASTM Standard Council of the Southern Pressure Treaters’ Association in D 245 involve adjusting strength properties of small clear accordance with principles originally established by the specimens of wood, as given in ASTM Standard D 2555- U.S. Forest Products Laboratory in the early 1950s and 06 (2011) (Establishing Clear Wood Strength Values), for contained in ASTM D 2899-12 (Standard Practice for effects of knots, slope of grain, splits, checks, size, duration Establishing Allowable Stresses for Round Timber Piles) of load, moisture content, and other influencing factors, and ASTM D 3200-74 (2012) (Standard Practice for Estab- to obtain reference design values applicable to normal lishing Allowable Stresses for Round Timber Construction conditions of service. Lumber structures designed on the Poles), respectively. These principles involve adjusting basis of working stresses derived from ASTM Standard D strength properties of clear straight grained poles to ac- 245 procedures and standard design criteria have a long count for knots, slope of grain, density, size of member, history of satisfactory performance. and other factors unique to timber poles. Reference design values for machine stress rated Specific methods used to establish reference design (MSR) lumber and machine evaluated lumber (MEL) are values are contained in D 2899 and are used by D 3200. based on nondestructive testing of individual pieces. Cer- These methods have been revised to reflect results of full- tain visual grade requirements also apply to such lumber. size tests of timber piles. The stress rating system used for MSR and MEL lumber Conditions of Use is regularly checked by the responsible grading agency Reference design values presented in this Supplement Copyright © American Wood Council. Downloaded/printed pursuant to License Agreement. No reproduction or transfer authorized. AMERICAN WOOD COUNCIL iv DESIGN VALUES FOR WOOD CONSTRUCTION – NDS SUPPLEMENT are for normal load duration under dry conditions of ser- vice. Because the strength of wood varies with conditions under which it is used, these reference design values should only be applied in conjunction with appropriate design and service recommendations from the NDS. Additionally, reference design values in this Supplement apply only to material identified by the grade mark of, or certificate of inspection issued by, a grading or inspection bureau or agency recognized as being competent. American Wood Council Copyright © American Wood Council. Downloaded/printed pursuant to License Agreement. No reproduction or transfer authorized. AMERICAN WOOD COUNCIL DESIGN VALUES FOR WOOD CONSTRUCTION – NDS SUPPLEMENT v TABLE OF CONTENTS Chapter/Title Page Chapter/Title Page 1 Sawn Lumber Grading Agencies ..............................1 3 Section Properties .............................................................................. 11 1.1 List of Sawn Lumber Grading Agencies 3.1 Section Properties of Sawn Lumber and Structural Glued Laminated Timber 2 Species Combinations ......................................................................3 2.1 List of Sawn Lumber Species 4 Reference Design Values .................................................. 31 Combinations 2.2 List of Non-North American Sawn Lumber Species Combinations 2.3 List of Structural Glued Laminated Timber Species Combinations LIST OF TABLES 1A Nominal and Minimum Dressed Sizes of 4F Reference Design Values for Non-North Sawn Lumber ....................................................... 13 American Visually Graded Dimension Lumber (2" - 4" thick) ......................................... 57 1B Section Properties of Standard Dressed (S4S) Sawn Lumber ............................................. 14 5A Reference Design Values for Structural Glued Laminated Softwood Timber (Members stressed 1C Section Properties of Western Species Structural primarily in bending) ........................................... 62 Glued Laminated Timber