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American Society of Heating and Ventilating Engineers Guide, 1937
Chapter 5--Heat Transmission Coefficients and Tables
Table 11. Coefficients of Transmission (U) of Various Types of Flat Roofs Covered with Built-Up Roofing
TYPICAL CONSTRUCTION
Without Ceilings
With Metax. Lath
and
Plaster Ceilings^
TYPE OP ROOF DECK
Thickness or
Roor Deck (Inches)
No
,0 RflFJNtf^/TU.L
1m
/urroKT/jT*
Precast Cement Tile
1H l
Coefficients are expressed in Btu per hour Per square foot per degree Fahrenheit difference in temperature between the air on the two sides, and are based on an outside wind velocity of 15 mph.
without ceiling--under side of WU ROOF EXPOSED
WITH METAL LATH ANE PLA5TER CEILI1*GS*
i
Rigid Insulation (2 in.)
Rigid Insulation ( K in.)
Rigid Insulation (1 in.) Rigid Insulation (2 in.)
a
a
.2 5
1
a
ao
a .2
oa "a jg *1
J3
s
3
a
0
*`f2i
. -o `5>
55
"*52> 2
a
.2
d
5 M
ao
-o -a
i -OrOt
3 S
AQ. u
.44
o
O U
o S5
X
.S a ja .2
*1 *o o
-a 'as s
a M ; Co rj> O
Xoi o O
A B C D E F G H I J K L M N : o :P
0.84 0.37 0.24 0.18 0.14 0.22 0.16 0.13 0.43 0.26 0.19 0.15 0.12 0.18 0.14 0.11
irwULAtlOONN i
fcOOe-fNGj
3
coHcutTe.
In/olatuw, 11
I..,' CE-tUMd
Concrete
Concrete Concrete
22 4i 64
lN/ULATlffl/
lOOFtHffi
/
immm
wiop7
tH/ULAtlW
ROOFING;
i
Wood Wood
Wood Wood
1>
1M6 2 4* .
5
6 7 8
iNJUl/frtOtt/ ROOPlNSi rLAJTCR. frOAM?
Gypsum Fiber Concrete*
(2 in.) on Plaster Board (H in.) Gypsum Fiber Concrete6 (3 in.) on Plaster Board
(H in.) Gypsum Fiber Concrete6
(2 in.) on Rigid Insulalation Board (M in.) Gypsum Fiber Concrete6 (2 in.) on Rigid Insula tion Board (1 in.)
injoLATiart/ R.O0FIK6*
Flat Metal Roofs
Coefficient of transmis sion of bare corrugated
iron (no roofing) is 1.50 Btu per hour per square
foot of projected area per
degree Fahrenheit dif ference in temperature, based on an outside wind velocity of 15 mph._______
Computed from factors marked by * in Table 2. ^Nominal thicknesses specified--actual thicknesses used in calculations.
`Gypsum fiber concrete--87K per cent gypsum, 12K per cent wood fiber.
2X 3H 2H 3
124
9 10 11 12
0.82 0.37 0.72 034 0.64 0.33
0.24
0.23 0.22
0.17 0.17
0.16
0.14 0.13 0.13
0.22
0.21 0.21
0.16
0.16 0.15
0.13 0.12 0.12
0.42
0.40 0.37
0.26
0.25 0.24
0.19 0.18
0.18
0.15
0.14 0.14
0.12 0.12
0.11
0.18 0.17 0.17
0.14 0.13
0.13
0.11
0.11 0.11
0.49 0.28 0.37 0.24 0.32 0.22 023 0.17
0.20
0.1$ 0.16 0.14
0.15 0.14 0.13 0.11
0.12 0.19 0.11 0.17
0.11 0.16 0.096 0.13
0.14 0.12 0.32
0.13 0.11 0.26 0.12 0.10 0.24 0.11, 0.091 0.18
0.21
0.19 0.17
0.14
0.16 0.15 0.14 0.12
0.13 0.12 0.11
0.10
0.11 0.15 0.10 0.14 0.097 0.13
0.087 0.11
0.12 0.10 0.11 0.095 0.11 0.092 0.096 0.082
0.40 0.25 0.18 0.14 0.12 0.17 0.13 0.11 0.27 0.19 0.15 0.12 0.10 0.14 0.12 0.097 0.32 0.22 0.16 0.13 0.11 0.15 0.12 0.10 0.23 0.17 0.14 0.11 0.097 0.13 0.11 0.091 0.26 0.19 0.15 0.12 0.10 0.14 0.11 0.10 0.20 0.16 0.13 0.11 0.09 0.12 0.10 0.087 0.19 0.15 0.12 0.10 0.09 0.12- 0.10 0.08 0.16 0.13 0.11 0.09 0.08 0.10 0.09 0.077
0.95 0.39 0.25 0.18 0.14 0.23 0.17 0.13 0.46 0.27 0.19 0.15 0.12 0.18 0.14 0.11
_
*These coefficients may be used-with sufficient accuracy for wood lath and plaster, or plaster board and W*ter ceilings. It is assumed that there is an air space between the under side of the rqpf deck and the QPPer side of the ceiling.
125