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202 CHAPTER 9 1957 Guide > Table 14B. Coefficients of Transmission (U) of Wood or Metal Construction Flat Roofs and Ceilings* {Concluded). DIRECTION OF FLOW DOWNWARD FLOW (SUMMER CONDITIONS) TYPE OF CEILING Type op Deck Built-up Roop in All Cases Rbbih1 Insulation Added on Top op Deck "COa3 gBdomoOe --3. O Resis tance None Gypsum Bd. (H in.) and Plas. MetaL j w Lath and Plas. ZCQ 5 a 5 a X .2 .2 sg p--cOeJ i tte* 3 < 1 < a0 0 55 ? 3 *a3 3 C-ad3D 2 *3 CL Acoustical Tile On Furring On Gyp sum Bd. (H in.) a .2 .5 a X &XX i 0.59 0.64 041 047 0.15 141 1.19 1.78 1M 9.10 Mateblal Rc R U U U U uU u U UV 0 Preformed slabs-- wood fiber and ce- ment binder 5.66 3 in. 6.40 None Flat Metal Roof Deck None 0.72 0.36 0.24 0.19 0.15 0.12 __ -- _ 1.59 9.78 4.17 6.96 6.67 8.55 0.20 0.14 0.67 0.35 0.23 0.18 0.15 0.12 0.10 0.15' 0.14 0.12 0.11 0.33 0.30 0.23 0.21 0.17 0.16 0.14 0.13 0.12 0.12 0.1JL 0.10 0.09 0.09 0.15 0.12 0.32 0.22 0.17 0.14 0.12 0.10 0.09 0.15 0.15 0.13 0.12 0.12 0.10 0.31 0.35 0.24 0.22 0.24 0.18 0.17 O.lti 0.14 0.14 0.14 0.12 0.12 0.12 0.11 0.1(1 0.10 0.09 0.09 0.09 0.08 0.13 0.12 0.13 0.12 0.11 0.10 0.10 0.10 0.26 0.22 0.24 0.21 0.10 0.17 0.10 0.16 0.15 0.14 0.14 0.13 0.12 0.12 O.U 0.11 0.11 0.11 0.K 0.10 0.00 0.00 0.00 0.00 0.08 0.08 0.08 0.08 * See text section Calculating Overall Coefficients (or basis of calculations. 6 To adjust U values see note just above this table. e Wood deck 1, 2, and 3 in. is assumed to be ductivity k is assumed to be 0.80. 1H and 2% in. thick, respectively. The thermal con ^ If a vapor barrier is used beneath roof insulation it will have a negligible effect on the U value. Fo '. information on .vapor barrier requirements see Chapter 10, Moisture in Building Construction. To use Table 16: f, 1. Find in Column 1 of the appropriate table the value for U obtained from:; Tables 5 through 15. ;|s. 2. If there is a column which exactly corresponds to the condition for which youg? desire the U value, read the answer in this column, opposite the Column 1 value,* Interpolate if necessary. || 3. If there is no column which fully corresponds to the condition for which yojfefc' desire the U value, then obtain the answer by means of two or more steps--eacg|p time using the value obtained in one step to reenter the same, table through Colun>D|| 1. In this way U values may be obtained for combinations of insulation in the framjj*: mg space. EXAMPLES OF THE USE OF TABLE 16 Example 3: Find the coefficient of transmission Ui of the frame wall shown as example at the top of Table 5: (a) With 2-inch blanket fibrous insulation between the studs and in contact wit'' the gypsum lath and, (b) With aluminum-foil-backed gypsum lath. Solution: According to Table 5, the U value for this construction with no insufe tion in the air space is 0.24. Referring to Table 16 Part A for walls, it is found tlgj corresponding to the value 0.24 in Column 1, the coefficient for conditions (a) spS (b) are: -4; (a) In Column 4, find Ui = 0.087. Use 0.09. (b) From Table 3, Section C, the effective emissivity E of aluminum foil is 0.&S In Column 8 find Ui = 0.173. Use 0.17. (Text continued on p. 208.) Heat Transmission Coefficients of Building Materials 203 Table 15. Coefficients of Transmission (U) of Pitched Roofs**6 Coefficients areexpressed in Btu per. (hour) (squarefoot) (Fahrenheit degree difference in temperature between the atr on the two sides), and are based on an outside wind velocity of IS mph for Keat flow upward and 7.6 mph for heat flow downward. 12343671 Example Resistances used are given below in ' this table or in Table S or 4- Construction (Heat flow up) Resistance (12) 1. Outside surface (15 mph wind).......................................... 0.17 2. Slate shingles (H in.)............... 0.05 3. Building paper............................ 0.06 4. Wood sheathing(*Hs in-)------ 0.98 5A. Ani-r-s-p--a--c--e-.......<...*.'...'.....`.................. 0.90 Example op Substitution Resistances used are given below in this table or in Table S or 4- Find 17 value for same construction with heat flow down (summer conditions) Total resistance.......................... 6.19 Deduct 1. Outside surface (15 mph wind)............................... 0.17 2s!. Air space...................*..>....: S0.:9S0 8. Inside surface (still air). . .. ! ' 0.66 Resistance deducted.......... 1.69 Total resistance.................... $.jg a ~ W-18.................. 0.31 value 0.31 in bold face type in table below. To Adjust U Values for Construction with Added Insulation between Framing Members, See Table 16. . ., Difference................................7Tso Add 1. Outside surface (7.5 mph ,, .............................0.96 2. Airspace......................... J.0J 8. Inside surface (still air). 0.76 Toj Total resistance................ s Si V " 1/R - V8.61................ 0.28 DIRECTION OF HEAT FLOW - UPWARD FLOW WINTER CONDITIONS DOWNWARD - FLOW SUMMER CONDITIONS Rafteb Space Rapter Space UNVENTILATED Not to be Fubtheb Insulated Unvbntilated Not to be Fubtheb Insulated /i Ttpe or Ceiling (Applied Dieectlt to Root Rapters) Asphalt Shingles Building Paper Asphalt Shingles Building Paper S> g& l 9 023 w: E f`5 a O O < I3 0.9S 1.09 0.87 *e si9? 3s-as "o s 3 3 O O gm < I 0.98 1.48 1.09 0.87 UU OjPBui'bd.'iM'i'i...................................... --" '> <M ) and H ,,t. *) W lath (H in'.) and H in. plas'. (sand Hetaffath and $4 in plas. (It. wt- *8*-) JUtal lath and 34 in plas. (sand agg.) IdtoI. bd. (H in.)....................... lasul. bd. lath and H in. plaa.1 Acoustical tiU (sand agg.) O.St 0.64 0.41 0.47 0.15 1.45 1.59 0.57 0.34 0.30 0.33 0.32 0.36 0.25 0.24 0.44 0.29 0:26 0.28 0.27 0.30 0.22 0.21 0.53 0.32 0.60 0.35 0.66 0.54 0.51 0.30 0.40 0.26 0.48 0.29 0.53 0.31 0.56 0.47 0.29 0.31 0.46, 0.28; 0.24 0.27 0.28 0.41 0.31 0.31 0.34 0.24 0 0.34, 0.52, 0.33| 0.50 0.37 0.61 0.25 0.34 0.25| 0.33 0.29, 0.25, 0.28, 0 0.29 0.25] 0.28j 0.30 0.32; 0.27 0.31 0.33 0.23 0.20 0.22 0.23 0.22 0.20 0.22 0.23 0.45 0.44 0.52 0.31 0.30 1.61 ,(R.i*inn' ..')) "oonn f,,yrpr""_"..*.>..d.....(..H....i.n...!.).................. 1.19 -9.10 --,, .a..nd,.YTt.in| .wp.lwas.j (sand w.m |avgg.j.i)j---u--.o1 s01j.4.u70.8a 0.24 0.26 0.21 0.23 0.33 0.21 0.23 0.19 0.20 0.28 0.23 0.25 0.20 0.22| 0.31 0.25 9.27 0.21 0.23| 0.34 0.33 0.37 0.26 0.30 0.521 0.22 0.24 0.20 0.211 0.29 0.20| 0.21 0.18, 0.191 0.26 0.22 0.23 0.19, 0.20 0.28; 0.23 0.24 0.20, 0.21 0.30 0.30 0.34 0.26 0.28 0.46 * To adh^.t^f100. Calculating Overall Coefficients for basis of calculations. * WheS.ffjaluw, * note above table. 6 Pitch of roof--45 deg. S! ^nstructintT- i1-u installed between rafters, the space above should be ventilated and in this case the 2]?".added inaiil^- *n calculation of U values. To adjust 17 values for pitched roof construction w in Tablets,*0? between framing members, use the average of values for horizontal and vertical heat ,0A an<l either 16C or 16D depending on direction of heat flow.