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• • <br /> • <br /> • <br /> NmisI + 0( ter riff Q► Fagot 7#P 4,4 <br /> •) • 727 "vet) re/iraNiet$, 644 efell felii•Mer <br /> AerastalY <br /> • ) l t,/ tS <br /> SCR o! ls ' , %4&, • <br /> taw <br /> • <br /> .,111.1VJl,i1 111 R oiiaLt. • <br /> • <br /> TABLE 308.4.2 <br /> • CLEARANCE REDUCTION.METHODS' <br /> REDUCED CLEARANCE WITH PROTECTION(inches)° <br /> Horizontal combustible assemblies <br /> Horizontal combustible assemblies located beneath the heat source and all <br /> located above the heat source vertical combustible assemblies <br /> Required clearance to combustibles Required clearance to combustibles <br /> without protection(inches)• without protection(inches) <br /> TYPE OF PROTECTIVE ASSEMBLY' 36 18 9 6 36 18 9 6 <br /> . Galvanized sheet steel,having a minimum thickness of 0.0236 inch(No.24 gage), <br /> mounted on 1-inch glass fiber or mineral wool batt reinforced with wire on the back,1 18 9 5 3 12 ' 6 3 3 <br /> inch off the combustible assembly <br /> Galvanized sheet steel,having a minimum thickness of 0.0236 inch(No.24 gage), 189 5 3 12 • 6 3 2 <br /> spaced 1 inch off the combustible assembly <br /> Two layers of galvanized sheet steel,having a minimum thickness of 0.0236 inch <br /> (No. 24 gage), having a 1-inch airspace between layers, spaced 1 inch off the 18 9 5 3 12 6 3 3 <br /> combustible assembly <br /> Two layers of galvanized sheet steel,having a minimum thickness of 0.0236 inch <br /> (No.24 gage),having 1 inch of fiberglass insulation between layers,spaced 1 inch off 18 9 5 3 12 6 3 3 <br /> the combustible assembly <br /> 0.5-inch inorganic insulating board,over 1 inch of fiberglass or mineral wool batt, 24 12 6 4 18 9 5 3 <br /> against the combustible assembly <br /> 3'/,inch brick wall,spaced 1 inch off the combustible wall — — — 12 6 6 6 <br /> 31/2inch brick wall,against the combustible wall — —• — 24 12 6 5 <br /> For SI: 1 inch=25.4 mm,°C=[(°F)-32]/1.8,1 pound per cubic foot=16.02 kg/ ',1.0 Btu in/(ft2•h•°F)=0.144 W/m2•K. <br /> a. Mineral wool and glass fiber batts(blanket or board)shall have a minimum ensity of 8 pounds per cubic foot and a minimum melting point of 1,500°F. <br /> Insulation material utilized as part of a clearance reduction system shall have a hermal conductivity of 1.0 Btu•in/(ft2•h•°F)or less.Insulation board shall <br /> be formed of noncombustible material. <br /> / b. For limitations on clearance reduction for solid fuel-bu:ming appliances,mason chimneys,connector pass-throughs,masonry fire places and kitchen ducts, <br /> see Sections 308.4.2.1 through 308.4.2.5. <br /> QUI of <br /> ,W <br /> /c/f <br /> 2015 INTERNATIONAL MECHANICAL CODE® r® 29 <br />