ASTM_D_245_-_22.pdf

Designation:D24522Standard Practice forEstablishing Structural Grades and Related AllowableProperties for Visually Graded Lumber1This standard is issued under the fixed designation D245;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This practice(1,2)2covers the basic principles forestablishing related unit stresses and stiffness values for designwith visually-graded solid sawn structural lumber.This prac-tice starts with property values from clear wood specimens andincludes necessary procedures for the formulation of structuralgrades of any desired strength ratio.1.2 The grading provisions used as illustrations herein arenot intended to establish grades for purchase,but rather toshow how stress-grading principles are applied.Detailed grad-ing rules for commercial stress grades which serve as purchasespecifications are established and published by agencies whichformulate and maintain such rules and operate inspectionfacilities covering the various species.1.3 The material covered in this practice appears in thefollowing order:SectionScope1Significance and Use3Basic Principles of Strength Ratios4Estimation and Limitation of Growth Characteristics5Allowable Properties for Timber Design6Modification of Allowable Properties for Design Use7Example of Stress-Grade Development81.4 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:3D9 Terminology Relating to Wood and Wood-Based Prod-uctsD143 Test Methods for Small Clear Specimens of TimberD2555 Practice for Establishing Clear Wood Strength ValuesE105 Guide for Probability Sampling of MaterialsIEEE/ASTM SI-10 Practice for Use of the InternationalSystem of Units(SI)(the Modernized Metric System)3.Significance and Use3.1 Need for Lumber Grading:3.1.1 Individual pieces of lumber,as they come from thesaw,represent a wide range in quality and appearance withrespect to freedom from knots,cross grain,shakes,and othercharacteristics.Such random pieces likewise represent a widerange in strength,utility,serviceability,and value.One of theobvious requirements for the orderly marketing of lumber isthe establishment of grades that permit the procurement of anyrequired quality of lumber in any desired quantity.Maximumeconomy of material is obtained when the range of quality-determining characteristics in a grade is limited and all piecesare utilized to their full potential.Many of the grades areestablished on the basis of appearance and physical character-istics of the piece,but without regard for mechanical proper-ties.Other grades,called structural or stress grades,areestablished on the basis of features that relate to mechanicalproperties.The latter designate near-minimum strength andnear-average stiffness properties on which to base structuraldesign.1This practice is under the jurisdiction of ASTM Committee D07 on Wood andis the direct responsibility of Subcommittee D07.02 on Lumber and EngineeredWood Products.Current edition approved Feb.1,2022.Published March 2022.Originallyapproved in 1926.Last previous edition approved in 2019 as D24506(2019).DOI:10.1520/D0245-22.2The boldface numbers in parentheses refer to references at the end of thispractice.3For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.13.1.2 The development of this practice is base