Designation:D245−22StandardPracticeforEstablishingStructuralGradesandRelatedAllowablePropertiesforVisuallyGradedLumber1ThisstandardisissuedunderthefixeddesignationD245;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.1.Scope1.1Thispractice(1,2)2coversthebasicprinciplesforestablishingrelatedunitstressesandstiffnessvaluesfordesignwithvisually-gradedsolidsawnstructurallumber.Thisprac-ticestartswithpropertyvaluesfromclearwoodspecimensandincludesnecessaryproceduresfortheformulationofstructuralgradesofanydesiredstrengthratio.1.2Thegradingprovisionsusedasillustrationshereinarenotintendedtoestablishgradesforpurchase,butrathertoshowhowstress-gradingprinciplesareapplied.Detailedgrad-ingrulesforcommercialstressgradeswhichserveaspurchasespecificationsareestablishedandpublishedbyagencieswhichformulateandmaintainsuchrulesandoperateinspectionfacilitiescoveringthevariousspecies.1.3Thematerialcoveredinthispracticeappearsinthefollowingorder:SectionScope1SignificanceandUse3BasicPrinciplesofStrengthRatios4EstimationandLimitationofGrowthCharacteristics5AllowablePropertiesforTimberDesign6ModificationofAllowablePropertiesforDesignUse7ExampleofStress-GradeDevelopment81.4Thevaluesstatedininch-poundunitsaretoberegardedasstandard.ThevaluesgiveninparenthesesaremathematicalconversionstoSIunitsthatareprovidedforinformationonlyandarenotconsideredstandard.1.5Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafety,health,andenvironmentalpracticesanddeter-minetheapplicabilityofregulatorylimitationspriortouse.1.6Thisinternationalstandardwasdevelopedinaccor-dancewithinternationallyrecognizedprinciplesonstandard-izationest...
