ASTM_D_6841_-_21.pdf

Designation:D684121Standard Practice forCalculating Design Value Treatment Adjustment Factors forFire-Retardant-Treated Lumber1This standard is issued under the fixed designation D6841;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.1.Scope1.1 This practice covers procedures for calculating adjust-ment factors that account for the effects of fire-retardanttreatment on design properties of lumber.The adjustmentfactors calculated in accordance with this practice are to beapplied to design values for untreated lumber in order todetermine design values for fire-retardant-treated lumber usedat ambient temperatures service temperatures up to 100 F(38C)and as framing in roof systems.NOTE1This analysis focuses on the relative performance of treatedand untreated materials tested after equilibrating to ambient conditionsfollowing a controlled exposure to specified conditions of high tempera-ture and humidity.Elevated temperature,moisture,load duration,andother factors typically accounted for in the design of untreated lumbermust also be considered in the design of fire-retardant-treated lumber,butare outside the scope of the treatment adjustments developed under thispractice.1.2 These adjustment factors for the design properties inbending,tension parallel to grain,compression parallel tograin,horizontal shear,and modulus of elasticity are based onthe results of strength tests of matched treated and untreatedsmall clear wood specimens after conditioning at nominalroom temperatures 72 F(22 C)and of other similarspecimens after exposure at 150 F(66 C).The test data aredeveloped in accordance with Test Method D5664.Guidelinesare provided for establishing adjustment factors for the prop-erty of compression perpendicular to grain and for connectiondesign values.1.3 Treatment adjustment factors for roof framing applica-tions are based on thermal load profiles for normal wood roofconstruction used in a variety of climates as defined by weathertapes of the American Society of Heating,Refrigerating andAir-Conditioning Engineers,Inc.(ASHRAE).2The solar loads,moisture conditions,ventilation rates,and other parametersused in the computer model were selected to represent typicalsloped roof designs.The thermal loads in this practice areapplicable to roof slopes of 3 in 12 or steeper,to roofs designedwith vent areas and vent locations conforming to nationalstandards of practice and to designs in which the bottom sideof the roof sheathing is exposed to ventilation air.For designsthat do not have one or more of these base-line features,theapplicability of this practice needs to be documented by theuser.1.4 The procedures of this practice parallel those given inPractice D6305.General references and commentary in Prac-tice D6305 are also applicable to this practice.1.5 The values stated in inch-pound units are to be regardedas standard.The SI units listed in parentheses are provided forinformation only and are not considered standard.1.6 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.1.7 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-uctsD5664 Test Method for Evaluating the Effects of Fire-Retardant Treatments and Elevated Temperatures onStrength Properties of Fire-Retardant Treated LumberD6305 Practice for Calculating Bending Strength DesignAdjustment Factors for Fire-Retardant-Treated PlywoodRoof Sheathing1This 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 June 1,2021.Published July 2021.Originally approvedin 2002.Last previous edition approved in 2016 as D6841 16.DOI:10.1520/D6841-21.2Available from American Society of Heating,Refrigerating,and Air-Conditioning Engineers,Inc.(ASHRAE),1791 Tullie Circle,NE,Atlanta,GA30329,http:/www.ashrae.org.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 S