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F�jf a firr-r�ated assem6ly has a onahour roting, does that mean !t wlll last one hour du�tng a real {irct / <br />�Na Every fire is di(feren4 so it would be impractical to design a test that fits all possible scenarios. The fire endurance , <br />rating is st�ictly for compaiing altemative materials and assemblies against one another. The one-hour rating represents a <br />60-minute endurance against the standard timc-temperature curve. <br />How rcalistic !s the comparison between the time-temperature curve developed for standard {ire <br />'��"enduronce tests and conditions in a rcal rcsidentlal /irci <br />Variations in fuel load, venlilation and ignition source make every fire different. This disparity makes it di(ficult to produce a <br />lime-tempeiatuie curve that reflects generalized fire conditions modeled for similar duration and intensity. Tests of simulated <br />room fires conduded by the Nationai B�reau of Standards (now the National Institute for Standards andTechnology) and <br />the forest Products Laboratory have resulted in time-temperetum curves that diRer noticeably from the standard arve. <br />(For further refeience to the time-temperature curve test, see "Fire Development and Wall Endurance in Sandwiih and <br />VJood-Frame Stivctures;' USDA, F5, Forest Products Laboratory, Research Paper FPL 364, March 1980; or "Fire <br />Development in Residential Basement Rooms;' National 8ureau of Standards, NBSIR, 80-2120.) Although these tests <br />demonstrated a peak temperature higher than the standard time-temperature curve during ihe first 60 minutes, the total <br />fire intensity in ea:h test was less. The standard time-temperature curve reflects a mom conservative approach to fire <br />development modeling compared to these al!emative test curves. <br />, —�,, <br />i� Whot is minimum membrnne Qrotectioni <br />'�A minimum of'Iz" thick unrated gypsum boaid ins.alled beneath ceiling iraming is recommended as a pintective <br />membrane—even in attics and basements. <br />Can Microllam° LVL be used as a substltute for sawn lumber or glurlamtnated beams in heavy <br />"tlm6er construction or jirc-rated assembllesl <br />Char rate tests on Microllamm LVL have determined it to be at least equivalent to any of the sawn lumber species from <br />which it is made. Flame spread tests yield lower Flame Spread Indices for Microllamm LVL than (or the source species. <br />However, no specific heavy timber or assembly testing has been conducted using Microllam� LVL. ��hem(ore, local building <br />o�cials grant individual approval based on char rate and tlame spread rate data. In the U.S., Microllamm LVL is specifically <br />approved for heavy timber construdion when minimum dimensional requirements am met,while approval in Canada <br />hinges on equal or larger-sizc substitution in fire-rated assemblies. <br />� <br />;� Con TlmberStrand� LSL be used as a substltute for sawn lumber in �'ire-rated assembHes <br />Yes. In both Canada and the U.S..TimberStrand° LSL is permiried as a substitute in fire-rated assemblies when used in the <br />same or larger dimensions as sawn lumber. <br />Additionally, in the U.S., a minimum thickness of I H+"Timber5trand'� LSL can be used in lieu of sawn lumber (or fire blocking. <br />Can Pamllam� PSL be subrtituted (or sawn lumber or glued laminated timber !n Meavy tim6er <br />applicatlonsl <br />Yes. All model code agencies in the US. and Canada mcognize Parallam�' PSL as c suitable allemative in heavy timber <br />construction when it meets or exceeds the minimum dimensional requiremenls. <br />Tesls conducted at Undeiwriters Laboratories Inc., Inchcape Testing/J�/arnock Hersey and Southwest Research Institute <br />have proven the fire resistance o( Parallam'� PSL equivalent to that of sawn lumber or glued laminated timber. <br />35 <br />fL�] <br />