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American Society of Heating and Ventilating, Engineers Guide, 1932
Table 32. Coefficients of-Transmission (U)
Note.--The figures on these pages are the combined coefficients op transmission of pitched
FOOT OF ROOF AREA PER 1 DEG FAHR DIFFERENCE IN TEMPERATURE BETWEEN THE AIR UNDERNEATH THE COEFFICIENTS ARE BASED ON ONE-THIRD PITCHED ROOFS, BUT ARE SUFFICIENTLY ACCURATE FOR ROOFS
Chapter 3--Heat Transfer Through Materials-and Constructions
op Pitched Roofs with Unheated Attics
roofs, unhbated attics, and top-floor ceilings, and are expressed in btu per hour per square CEILING AND THE OUTSIDE AIR. AN AVERAGE WIND EXPOSURE OF 15 MILES HAS BEEN ASSUMED. THESE RANGING FROM ONE-QUARTER PITCH TO ONE-HALF PITCH.
The values of U in this Table are based on the faMcwmq internal Conduc-
-twities or Conductances which areexpressed in B.tu.per Ur: perSq.Ft. perPF
Asphalt or Composition Coofmq
6.50 as applied
Asbestos Shmqles
6.00 as applied
Slate Sbtnqles
.
10.37 per V*
Wood. ( Yellow Pine or Fir)
\.00 perl*
Wood. Lath 4 Plaster
2.00 as applied
Plaster board
3."I3 peri*
Plaster (Gypsum)
Z.32 per p
(2iqid Insulation (board form) Flexible Insulation
0.33 per V 0.27 per 1"
Cork board
0.30 per 1*
Cellular Gypsum (18*)
0.W per 1"
Flatted Gypsum, Dry (IS*)
0.34 per. 1
No Attic Floormq
oofinq
Insulation
Wood fPlaTler \ K.tqid riliqtd
V<> and Q.oof
between Ceilinq Lath and board ^ Insulation Insulation
-D
g
Sheathinq
Joists
3
Plaster Plaster 4 Plaster f Fluster Ceilinq Ceilinq Ceilinq Ceilinq
2
a &cD
i None
2 Wood
Flexible 0
3
Shmqles on Wood 5tnps4
2* Cellular * Gypsum
r. Flaked 4 Gypsum
5 Asphalt
6 Sbtnqles or
Composition
7 Coofwq on Wood
8 Sheathinq
None
Flexible b
2" Cellular Gypsum
V Flaked Gypsum
*
1 None 2-iqid Asbestos
10 Shmqles on Wood
It Sheathinq
Flexible b
2" Cellular Gypsum
12
2" Flaked Gypsum
13 None
SlateorTile
14 and Coot tnq i Flexible
Felton Wood
IS SbeoAhtnq
2" Cellular Gypsum
Ib
2" Flaked -Gypsum
b A. ^
0.263 0.264 0.110 0.141
0.141 0.141 0.116 0.016 0.12b 0.126 0.107 0.010 0.012 0.012 0.081 0.071 0.272 0.273 0.114 0.143 a 143 QI43 0.118 0.017 0.128 0.128 0.108 0.010 0.013 0.013 0.081 0.071 0.271 0.272 0.114 0.143 0.143 0.143 0.118 0.017 0.I2& 0.128 0.108 0.010
Q013 0.013 0.081 0.071 0.280 0.281 0.118 0.145 0.145 0.145 0.120 0.018 0.130 0.130 6.101 0.010 0.013 0.013 0.082 0.072
Based on 1 in. by 4 in. spaced 2 in. bCan also be applied to underside of ceiling joists with furring strips between insulation and ceiling. . oBased on actual thickness of 1 in. lumber of approximately *36 in. . " v> dThe coefiident used for'cellular gypsum, 0.59 is for 18 lb. weight--weights as low as 12 ib'. may be used.
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Typical Construction
Coot Sheathinq-.
Unheated Attic ^ S--Attic Floormq
^^^^t^^^ Plaste'rCeihnq
foase
f*<>* Yellow Pine Attic Floormq c
It" Cork- 2'Cork- Wood $ Plaster T; Biqid TUiqid \\ Cork- 2* Corkboard^ board 4 Lath and board 4 Insulation Insulation board^ boards Plaster Plaster Plaster. Plaster 4 Plaster 4 Plaster Plaster Plaster Ceilinq Ceilinq Ceilinq Ceilinq Ceilinq Ceilinq Ceilinq Ceilinq
E. F G u i j K L
0.106 0.088 0.172 0.172 0.136 0.101 0.087 0.074 0.078 0.068 0.101 0.101 0.014 0.080 0068 0.060 0.074 0.064 0.101 o.tot - 0.088 0.076 0.064 0.057 0.061 0.054 0.078 0 078 0.070 0.062 0.053 0.041 0.107 0.088 0.175 0.175 0.138 O.UO 0.087 0.075 0.071 0.068 o.uo 0.110 0.015 0.081 0.068 0.060 0.015 0.064 0.102 0.102 0.088 0.076 0.064 0.057 0.061 0.054 0.078 0.078 0.070 0.062 0!054 0.041 0.107 0.088 0.175 0.175 0.138 O.UO 0.087 0.075 0.071 0.068 0.110 0.110 0.015 0.081 0.068 0.060 0.075 0.064 0.102 0.102 0.088 0.076 0.064 0.057 0.061 0.054 0.078 0.078 0.010 0.062 0.054 0.041 0.108 0.081 0.171 0.171 0.140 o.m 0.088 0.076 0.080 0.068 0.111 0.IW 0.016 0.081 0.068 0.060 0.076 0.065 0.103 0.103 6.081 0.076 0.065 0058 0.061 0.054 0.078 0.018 6.070 6.062 0.054 0.041
Based on 1 in. by 4 in. spaced 2 in. bCan also be applied to underside of ceiling joists with furring strips between insulation and ceiling. Based on actual thickness of 1 in. lumber of approximately in. <*The coefficient used for cellular gypsum. 0.59 is for 18 lb. weight--weights as low as 12 lb. may be used.
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