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HEATINC VENTILATING AIR CONDITIONING CUIDE 1941
Table II. Coefficients of Transmission (U) of Various Types of Flat Roofs Covered with Built-Up Roofingo
TYPICAL CONSTRUCTION
Without Cbiungs
With Metal Lath
and Plaster Ceilings*
TYPE OF ROOF DECK
Thickness
Roor Deck (Inches)
No.
/Cl)l xooriKi /tut
*VePe#M7^
tnjJVVLLAfiUUOOttii,
HOOPINGrj
/
COMCRETe.^
.Cast RooFtNtfi /Tile.
*T/UffOT.T/J,L
Precast Cement Tile
IH 1
in/dut1011/
ILOOFIHOj
7
cOHCEtre.'' Ul?l
Concrete Concrete Concrete
2 4 64
lN/U/ULL<AC.UnOHK/
:WIDPHUCa
wwm utavS
Wood Wood Wood
Wood
1* lHh 2* 4*
5
6 7
8
IWULATKJn,
2
'xsUr'xxm ft 4 XT C It &SAitP'
W/ULAT1W/
ROOPIKCi
'
IM/ULA^rt/ TLOppiHtfi.
CIWKy. :\ PLA/TCR. &ACLC^
twuuTMru RPOFIKtfj
CQUH6
Gypsum Fiber Concrete* (2 in.) on Plasterboard 1% in.)
Gypsum Fiber Concrete* (3 in.) on Plasterboard CH in.)
Gypsum Fiber Concrete* (2 in.) on Rigid Insulalation Board (M in.)
Gypsum Fiber Concrete* (2 in.) on Rigid Insula tion Board (1 in.)
Flat Metal Roofs Coefficient of transmission of bare corrugated iron (no roofing) is 1.60 Btu per hour per square foot of projected area per degree Fahrenheit difference in temperature. based on an outside wind velocity of 15 mph.
"Nominal thicknesses specified--actual thicknesses used in calculations. ^Gypsum fiber concrete--87M Per cent gypsum, 12>$ per cent wood fiber.
2H 3M
2H
3
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9 10 11 12
13
CHAPTER 3. HEAT TRANSMISSION COEFFICIENTS AND TABLES
Coefficients ore expressed in Btu pa hour pa square foot pa degree Fahrenheit difference in tempaature between the air on the two sides,
and are based on an outside wind velocity of Id mph.
WITHOUT CEILING--UNDER SIDE OF WITHUU ROOF EXPOSED
WITH METAL LATH AND PLASTER CEILINGS*
a
%
jOa
0Q a
1a
A3
a -o
o 55
*et
Rigid Insulation (1 in.) Rigid Insulation (1 In.)
5 _d
c
i
5_ao ao a
15
*3 a
*a a
"E0
d
1 29
*aos Ja3 a
I 1'So
*'e2y
2M O
O
A S o
j* o8
a
o *a
5d ja M
a0 '&
e0an
jd
.2 s
1|
o a a 'S 8 o OO
ABCD E FG H i j K LMNo
_d N
i
ea* o8
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
0.82
0.24 0.17 0.14 0.22
0.72
0.23 0.17 0.13 0.21
0.64 0.33 0.22 0.16 0.13 0.21
0.16 0.13 0.42 0.26 0.19 0.15 0.12 0.18 0.14 0.16 0.12 0.40 0.25 0.18 0.14 0.12 0.17 0.13 0.15 0.12 0.37 0.24 0.18 0.14 0.11 0.17 0.13
o.n 0.11 0.11
0.49 0.37 0.32
0.23
0.28 0.24 0.22
0.17
0.20
0.18 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
0.13 0.12
0.11
0.12 0.32 0.11 0.26 0.10 0.24 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 plasterboard 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.
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