Document v1MXyMQQv63mr898omB8vG4XR

104 Chapter 4 1945 Guide ___________________________________ i' Table 14. Coefficients of Transmission^ /)of~Flat-RoofsGovered-with-------Built-up Roofing. With Lath and Plaster Ceilings5* (See Table 13 for Flat Roofs with No Ceilings) These coefficients are expressed in Btu per hour Per square foot Per degreeJPakrenhett difference in temperature between the air ton the two sides. and are based on an outside wind velocity of 16 mpk. TYPE OF ROOF DECK INSULATION ON TOP OF DECK (Covered with Built-Up Rooting) Root Decs (Inches) No Insula tion Insulating Board (Thickness Below) Min. 1 In. 1M In. Coreboard (Thickness. Below) lMIn. Flat Metal Roof Deck 1HJOUTWH/ WOFIKtfi Precast Cement TUe fit *T/urroTLT/X* ctiuttnF3 " 1H in- 0.43 0.18 0.14 Concrete true ROOF1N4. ccHOte-Te.yw 2 in. 0.42 056 0.19 0.15 0.12 0.18 0.14 0.11 4 in. 0.40 055 0.18 0.14 0.12 0.17 0.13 0.11 057 0.24 0.18 0.14 0.11 0.17 0.13 0.11 Gypsum and Wood Fiber4 on M in. Gypsum Board Irl/ULtfftan/ 2Min. 3M in- 057 0.19 0.15 0.12 0.10 0.14 0.12 0.097 053 0.17 0.14 0.11 0.097 0.13 0.11 0.091 Wood* Ut/uUiLAAT|IiTenn>. RtoOFin^j m weep zw- 1 in. IHin. 2 in. 3 in. 052 051 0.16 0.13 0.11 0.15 0.12 0.10 056 0.19 0.15 0.12 0.10 0.14 0.11 0.095 054 0.17 0.14 0.11 0.097 0.13 0.11 0.18 0.14 0.12 0.10 0.087 0.11 0.096 "Calculations based on metal lath and {plaster ceilings, but coefficients may be used with sufficient accuracy 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. . *87M per cent gypsum, 12M per cent wood fiber. Thickness indicated includes M in. gypsum board. "Nominal thicknesses specified--actual thicknesses used in calculations. Heat Transmission Coefficients ^Figures in Columns I, J, K and L m ay be used w ith sufficient accuracy fo r rig id asbestos'shingles on wood sheathing. L a ye r o f slater's fe lt neglected. fSheathlng and wood strips assumed in. thick. ^Plaster assumed % In. thick. Plaster assumed M in. thick. /N o a ir space Included in 1-A, 1-E or 1-1; all other coefficients based on one a ir space. " ' 105