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T able 12. Coefficients of T ransmission U) of Pitched R oofs"(
Coefficients are expressed in B tu per hour per square fo o t Per degree Fahrenheit difference in tem perature between the a ir on the two sides, and are based on an outside w in d velocity o f 15 mph.
Heating Ventilating Air Conditioning Guide 1939
0.049 0.045
| 0.070 | 0.062 j 0.056
| 6.080 | 0.071
| 0.19 | .0,18 | 0.14 | 0.11 | 0.098
0.048 0.044
: 0.092 | 0.078 | 0.069
| 0.089
0.059
| 0.11 . 1| 0-11
0.32 j| 0.32 11 - 24 I| 0.23 | 0.17 10.13 | 0.11
(Til K) pitre (mi z) pjroquiOQ
-
o
so
,
0.14 .n
| 0.16 | 0.12 :
('"! M) "W Pn" (! HD i"wo
X
otoo o
, 0.075 | 0.068
(mi H)
P113
(*tn i) uopepsai pphx
0
CtoOO
1
e:
0.21
|
1
(mi y)
P0*
(mi y) uoiiB|QU] paftu
fc
t- o
oW o8 (mi y) aoi^einsui pi3ry
tto-o-
o
to so d
00 o d ot> g o
0.062 0.058 0.058
| tro
1 ZZO 1
|| 0.18
i1o . ii
0.064 i 0.064
| 0.087
0.083 | 0.083 |
pan ^}\rj poo^\ o
( HI pno ri!K)Praia"nij
u
C! %)
(pseodxg ustjva) Jmjraoou
<
| 0.29 |10.21 I 0.12
| 0.29 |10.21 | 0.12
1
'08 01
o0to4 o to 0o0 d.
0.063
i
0.34
1
| 0.13
ci n
N
o** 00
C4
dd
00
00
C4
o` o
0.065
t 2
0.46 0.22
1
0.13
0 .6 6
1
INSULATION BETWEEN
ROOF RAFTERS
5o5
- r* *o
IO o
00 o
j 2 in. Flexible*
| Bright Aluminum Foil* |
| None |
] 1 in. Flexible*
Z% in. Rock Wool*
| 2 in. Flexible* J
Il
Bright Aluminum Foil? J
- 1
in. Flexible*
1
o
'"I
SsE
3S
*o3 SS2
aOt e
*ra=t.gvX>l.
.S g?a C4>cZ
CO
EC S-'SS jll
2 '*3 *o 3
| None.
Sheathing^
Slate or Tile Roofing* on Wood
Shingles, Composi tion Roofing, or
Asphalt Shingles, Rigid'Asbestos
x*'
Wood Shingles on Wood Strips6
TYPE OFROOFING AND
ROOF SHEATHING .
TYPICAL CONSTRUCTION
?* a r* *>
*aIsa'S0 "0
`otf gS-o S-o-o^SS
* rt`5ro m ,, I So 3 ib.gZ<$< .
114
Chapter 5. Heat Transmission Coefficients and Tables
13 coefficients of Transmission (U) of Doors, Windows, Skylights
^abLE
and Glass Walls
tire based on a wind velocity of 15 mph, and are expressed in Btu per hour per square foot per
CoeJfcijfNj*
difference in temperature between the air inside and outside ofthe door, window, skylight or wall
A. Windows and Skylights
Description
V
Single--............................
Nominal Thickness
Inches
1
IK lH
2
2H
3
B. Solid Wood Doorsc
Actual Thickness
Inches
1H6 154s m m 2H 2H
1.13"." 0.45" 0.281"
u
0.69 0.59 0.52 0.51 0.46 0.38 0.33
C. Glass Walls
Description
Hollow glass tile wall, 6 x 6 x 2 in. thick blocks, wind velocity
V
0.60 .0.48
See Heating, Ventilating and Air Conditioning, by Harding and Willard, revised edition, 1932.
Computed using C = 1.15 for wood;/! = 1.65 and/o " 6.0.
....................
It is sufficiently accurate to use the same coefficient of transmission for doors containing thin wood
panels as that of single panes of glass, namely, 1.13 Btu per hour per square foot per degree difference
between inside and outside air temperatures.
.
it is probable that the values of U for these two. types of roofs will compare favorably.
The thicknesses upon which the coefficients in Tables 3 to 13 inclusive, are based are as follows:
Plaster (on wood lath, plasterboard, rigid insulation, form, or corkboard)__________________________ _______
Slate (roofing)...... ........................................ |1J
Stucco on wire mesh reinforcing___ _____________ ;_____
Tar and gravel or slag-surfaced built-up roofing._______ 1-in. lumber (S-2-S)_________ ________ _____ ;______ ;_____
1/4-in. lumber (S-2-S)______________ ________ _________ 2-in. lumber (S-2-S)................... ..... ......................... ............
2J4-in. lumber (S-2-S)________ _______ __________; 3-in. lumber (S-2-S)
4-in. lumber (S-2-S)...... ............................... ........................
Finish flooring (maple or oak)_________ :___________ .......
in. ' in.
Hi Hi
-1^6
-m - 2H - 2H
- 3%
Solid brick walls are based on 4-in. hard brick (high density) and the
remainder common brick (low density). Stucco is assumed to be 1-in.
thick on masonry walls. Where metal lath and plaster'are specified, the metal lath is neglected.
115