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200 CHAPTER 9. 1951 Guide Table 16. Coefficients of Transmission (I/) of Flat Roofs Covered with Built-up Roofing. With Lath and Plaster Ceilings" (See Table 15 for Flat Roofs with No.Ceilings) That coefficients are expressed in Btu per (lour) (square fool) (Fahreahcxl degree difference in temperature between the air on the two tide*), and are based on an outside wind velocity of IS mph. Type op Roof Decs Thick ness 07 Roof Deck (Inches) 0ULATION Insulation on Top of Deck (Covered with Built-Up Roofing) Insulating Board (Thickness Below) Ia. 1 1 In lUa- 2 In. CORKBOARD (Thickness Below) 1 T_ 11, T-. 2'T-- A B CDE F GH num ber Flat Metal Roof Deck W0P|KyitffJ>OUTMf/y. rtaTAu^ ^ 1,1 ' j CEIUNC r 1 12 Precast Cement Tile ftoeriN6i y|L Wcl Ht/tfrroMVjr ClIUHaS Concrete INJOLATtOff, ' aeoFiHCj / cohwc.t&< J;l* CL tLWtf/. 1} in. 0.43 0.26 0.19 0.15 0.12 0.18 0.14 0.11 13 - 2 in. 4 in. .6 in. 0.42 0.40 0.37 0.26 0.25 0.24 0.19 0.18 0.18 0.14 0.14 0.14 0.12 0.12 0.11 0.18 0.17 0.17 0.14 0:13 0.13 0.11 o.n. 0.11 14 15 16 Gypsum Fiber Concrete* iLon } in. Gypsum Board iM/ULAfWfi MPFiN<Tr y I ClrJOiK?. eipjVK. eAK.9? . CtMAXtC* 2} in. 3} in. 0.27 0.19 0.15 0.12 0.10 0.14 0.12 0.097* 17 0.23 0.17 0.14 ' 0.11 0.097 0.13 0.11 0.091 18 Wood tnmATi0n> - ROOFirtCl / , fr"? n, CUUMd^ T in. 1} in. 2 in. 3 in. . 0.31 0.26 0.24 0.18 0.21 0.19 0.14 6.16 0.15 0.14 0.12 0.13 0.12 0.11 0.10 0.11 0.10 0.097 0.087 0.15 0.14 0.13 0.11 0.12 0.11 0.11 0.095 0.10 0.095 0.092 0.082 19 20 21 22 Calculations based on metal lath and plaster ceilings, but coefficients may be used with sufficient ac curacy for gypsum lath or wood lath and plaster ceilings. It is assumed that there is an air space between the under side of the roof deck and the upper side of the ceiling. 6 87} percent gypsum, 12} percent wood fiber. Thickness indicated includes } in. gypsum board. * Nominal thicknesses specified--actual thicknesses- used in calculations. HeatTransmission Coefficients of Building Materials 201 T a b l e 17. Co effic ien ts of T ransmission ( t f ) of Pitc h ed R oofs Coefficients are expressed tn B tu per (hour) (square foot) (Fahrenheit degree difference n temperature between the a ir on the two sides), and are based on an outside w ind velocity o f IS mph. aM 2 i it to J2 |a . fl-U J .2 -e 3 O *2 *-a aa oj H MM 3 11: 2 W 8.: a *2 < I S 2-- 0 *- a a - m81_1__1_ , I J o Ota 3 tu P* fc