Document NGzkNw835EwK30gQ3gMEo969E
T able 12. Coefficients of T ransmission V ) of Pitched Roofs(
Coefficients ore expressed in B tu per h o u r per square fo o t Per degree F ahrenheit difference in tem perature between the a ir on the tw o sides,
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and are based on a n outside w in d velocity o f 16 m ph.
Heating Ventilating Air Conditioning Guide 1938
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Chapter 5. Heat Transmission Coefficients and Tables
Table 13. Coefficients of Transmission (U) of Doors, Windows, Skylights
1`
and Glass Walls
_ are based an a mind velocity of IS mph, and are expressed in Bin per hoar per square foot per degree Fahrenheit difference in temperature between the air inside and outside of the door, window, skyhght or wall
A. Windows and Skylights
Description
u
Single-............ -.......................................................................... -..............
T11pk----------........
Nominal Thickness
Inches
i
m m 2 2 34 3
B. Solid Wood Doorsb. c
Actual Thickness
Inches
% lHs me m. m
256
1.13. c 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 15 mph, outside surface; still air, inside surface.-... Still air, outside and inside surface--..............................................--
' U
0.60 0.48
See Heating, Ventilating and Air Conditioning, by Harding and Willard, revised edition, 1932. ^Computed using C = 1.15 for wood;/i ** 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:
Brick veneer___ __________________ :__________________________ 4 " in.
Plaster and metal lath_____ 1_______________ ___________________ M in.
Plaster (on wood lath, plasterboard, rigid insulation, board
form, or corkboard).............. ................................... ....................... 34 in.
Slate (roofing)_______________________________________________ }6 im
Stucco on wire mesh reinforcing 1 in.
Tar and gravel or slag-surfaced built-up roofing.______________ 56 in.
1-in. lumber (S-2-S)256z m.
13'6-in. lumber (S-2-S)_____________ ____ _:. _15fe in.
2-in. lumber (S-2-S) :_______________ ................. .............. :____ 156 in.
234-in. lumber (S-2-S)______________ _________________________ 234 *n.
3-in. lumber (S-2-S) 2% in.
4-in. lumber (S-2-S)
356.in.
Finish flooring (maple or oak)1.in.
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.
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