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hundred years in one form or another,but its use has Heavy Timber Requirements <br /> increased along with renewed interest in exposed The fire resistance of heavy timber construction is based <br /> wood buildings.This construction type is unique in that on the inherent size of large timber elements.In a fire,larg� <br /> fire-resistive behavior is based in part on the inherent and members tend to retain their load-carrying ability longer <br /> long-demonstrated fire resistance of large solid wood <br /> than members with small cross-sections;this is because a <br /> framing.Structural wood components are permitted in floors, char layer forms on the surface while the interior remains <br /> roofs and interior walls when they meet minimum cross- undamaged and structurally sound. IBC Section 2304.11 (IBC <br /> section sizes. Per IBC Sections 602 4.1 and 602.4.2,exterior 2015 Section 602.4)provides minimum heavy timber sizes for <br /> walls required to have a fire-resistance rating of 2 hours columns,floor framing and decking, roof framing and decking, <br /> or less are also permitted to use FRTW framing, or CLT and walls. <br /> when covered with FRTW sheathing or noncombustible <br /> materials. In general, heavy timber components used in These minimum nominal sizes are applicable to solid sawn <br /> Type IV construction (called Type IV-HT in the 2021 IBC) wood members. However, in consideration of engineered <br /> can be exposed. wood products, IBC Table 2304.11 (IBC 2015 Table 602.4) <br /> provides equivalent glulam and SCL sizes that qualify as <br /> heavy timber <br /> TABLE 1: <br /> Heavy Timber Minimum Member Sizes <br /> etc r 3 decking planks w/15/32 WSP`;or <br /> et—E. Floor decking 4 boards on edge INLT)w/15/32'WSP;or <br /> CLT <br /> ii 1•' �...,, <br /> rub u r pp 2'decking planks;or <br /> ;air: <br /> -�,,,..• Roof decking 3'boards on edge(NLTE or <br /> V ai Ii 3'CLT <br /> pi �T Source:IBC Section 2304.11 <br /> •WSP=Wood Structural Panel <br /> ®Albert Vecelka/Esto <br /> TABLE 2: P ""'� w Ck I <br /> Minimum Dimensions of 1 <br /> Heavy Timber Structural Members <br /> S3k,5" wisely DaPkh emh ..4xir 'I^i .alcMe' 'yY�th erc5+. ,L1ePN. ;,,. <br /> Floor loads only Columns 8 8 6-3/4 8-1/4 ] 7-1/2 <br /> or combined floor <br /> and roof loads Wood beams and girders 6 10 5 10-1/2 5-1/4 9-1/2 <br /> Columns 6 8 5 8-1/4 5-1/4 7-1/2 <br /> Roof loads only Framed timber trusses <br /> 41, 6 3° 6-7/8 3-1(2° <br /> and other roof framing' <br /> Source IBC Table 230411/See IBC for footnotes <br />