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f�ite o( char is one charadeiistic used to evaluate wood producu. Although no ASTM or CANIULC test standards currently <br />e�cist for deteimining rate of char, most wood product te�ting laboratories use similar procedures. The test specimen is <br />bumed for a measuned time period using a single radiant energy source. The specimen is then extinguished and the <br />rcmaining section measuied. The deplh o( char divided by the time i; the char rate. A smaller char rate number indicales <br />a slower ratc o( burn. <br />Comparison oi Char Rates for Parallam� PSL,TimberStrand� LSL� <br />Microllam� LVL,TJIp Joist with Performance PIus�Web and Several <br />Common Species of Structural Lumber <br />( I) Southwest Rcscarth Institutc, Rojcct No. 01- I(M6�001 <br />(2) TMDAIntematronal,Pmjttt No.li(iE5F91013 <br />(3) Weycituiner Reseaich 8 Devclopmrnt Repert <br />No.991 � 1763 <br />(-0) Wood I-landboolc USDAfSl�gnculwre Nandbook 72. <br />�ev. 1987. pp. I S-3 <br />(5) Nominal char ralcx Bry <br />Flame spread rating is used to evaluate the sur(ace Oammability of a material or product The test slandards for this are ASTM <br />E-84 in the United States and CAN/ULC 5102 in Canada. These two standards are essentially the same. The Flame Spread <br />Class is used by the model building codes to rate building content and suriace finishes. A low rating number means slow (lame <br />� spread. <br />Comparison of Flame Spread of Parallam� PSL, <br />TimberStrand� LSL, Microllam� LVL, OSB and <br />Several Common Saecies of Structural Lumber <br />5o II or 8 <br />I�0 III or C <br />50 II or B <br />74 -172 III or C <br />70 -100 III Of C ( I) Wamock Hcrscy. Fim lalwralory Uivision, ficport No.3521 <br />I 30 • 195 I�� O� C (2) �'!S Co�poration, Renort No. WR�94105 <br />60 -75 II o� B (3) Wamock I-Icrzcy. Fim Labaatory Division Rc�wrt No. 3815 <br />100 III of C (4� Design for Codc Acccplancc I, �mcrican Wood Camcil <br />I O$ - 230 III o� C �5) Wood Handtwok USDA FSl�gricvllure Hrndbook 77, <br />mv. 1987 pp. I S-5 <br />6oth o( these measures—char rate and flame spread dass—reveal thatTrus JoisYs engineered lumber products and sawn <br />lumber have comparable fre per{ormance charaderistia. This should not be surprising sinceTrus Joist pivduds are composed <br />of 9q% to 96% wood fiber. <br />The question is (requently asked: Do adhesives conlribute to (lame spread or act as an accelerant to promote fire or sofl.en in <br />� 6re? The answer is no. All adhesives used by Trus Joisl belong to a dass known as thermosets, whic� mquire heat to cure <br />lhem. Once cured, the process is in�versible and lhe cumd products mtain iheir use(ul properties at temperatures up to their <br />ignition point. The ignition point of the adhesives is higher than that of the wood they bond. Once bumed, these adhesives will <br />producc a charred by-produd similar to wood. � <br />S <br />