ASTM_D_6305_-_08_2015e1.pdf

Designation:D630508(Reapproved 2015)1Standard Practice forCalculating Bending Strength Design Adjustment Factorsfor Fire-Retardant-Treated Plywood Roof Sheathing1This standard is issued under the fixed designation D6305;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.1NOTEEditorial corrections were made to Appendix X1 in October 2015.1.Scope1.1 This practice covers procedures for calculating bendingstrength design adjustment factors for fire-retardant-treatedplywood roof sheathing.The methods utilize the results ofstrength testing after exposure at elevated temperatures andcomputer-generated thermal load profiles reflective of expo-sures encountered in normal service conditions in a widevariety of continental United States climates.1.2 Necessarily,common laboratory practices were used todevelop the methods herein.It is assumed that the procedureswill be used for fire-retardant-treated plywood installed usingappropriate construction practices recommended by the fireretardant chemical manufacturers,which include avoidingexposure to precipitation,direct wetting,or regular condensa-tion.1.3 The heat gains,solar loads,roof slopes,ventilation rates,and other parameters used in this practice were chosen toreflect common sloped roof designs.This practice is applicableto roofs of 3 in 12 or steeper slopes,to roofs designed with ventareas and vent locations conforming to national standards ofpractice,and to designs in which the bottom side of thesheathing is exposed to ventilation air.These conditions maynot apply to significantly different designs and therefore thispractice may not apply to such designs.1.4 Information and a brief discussion supporting the pro-visions of this practice are in the Commentary in the appendix.A large,more detailed,separate Commentary is also availablefrom ASTM.21.5 The methodology in this practice is not meant to accountfor all reported instances of fire-retardant plywood undergoingpremature heat degradation.1.6 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.1.7 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:3D9 Terminology Relating to Wood and Wood-Based Prod-uctsD5516 Test Method for Evaluating the Flexural Properties ofFire-Retardant Treated Softwood Plywood Exposed toElevated Temperatures3.Terminology3.1 Definitions:3.1.1 Definitions used in this practice are in accordance withTerminology D9.3.2 Definitions of Terms Specific to This Standard:3.2.1 bin mean temperature10F(5.5C)temperatureranges having mean temperatures of 105(41),115(46),125(52),135(57),145(63),155(68),165(74),175(79),185(85),195(91),and 200F(93C).4.Summary of Practice4.1 The test data determined by Test Method D5516 areused to develop adjustment factors for fire-retardant treatmentsto apply to untreated-plywood design values.The test data areused in conjunction with climate models and other factors andthe practice thus extends laboratory strength data measuredafter accelerated aging to design value recommendations.1This practice is under the jurisdiction of ASTM Committee D07 on Wood andis the direct responsibility of Subcommittee D07.07 on Fire Performance of Wood.Current edition approved Sept.1,2015.Published October 2015.Originallyapproved in 1998.Last previous edition approved in 2008 as D6305 08.DOI:10.1520/D6305-08R15E01.2Commentary on this practice is available from ASTM Headquarters.RequestFile No.D071004.3For 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 States1 5.Significance and Use5.1 This practice develops treatment factors that shall beused by fire retardant chemical manufacturers to adjust bendingstrength design values for untreated plywood to account for thefire-retardant treatment effects.This practice uses data fromreference thermal-load cycles designed to simulate tempera-tures in sloped roofs of common design to evaluate productsfor 50 iterations.5.2 This practice applies to material installed using con-struction practices recommended by the fire retardant chemicalmanufacturers that include avoiding exposure to precipitation,direct wetting,or regular