PDFWAC 51-11C-610226

Tables A102.2.6—Assembly U-factors for roofs with insulation entirely above deck.

Table A102.2.6(1)
Assembly U-factors for Roofs with Tapered Insulation Entirely Above Deck Single Slope Rectangular to One-sided,e,f,g,h
(Uninterrupted by Framing)
 
Rated R-value of Insulation at Maximum Condition (Rmaxc)
1
5
10
15
20
25
30
35
40
45
50
55
60
Rated R-value of insulation at a Minimum Condition (Rminb)
1
0.562
0.306
0.213
0.168
0.140
0.121
0.107
0.097
0.088
0.081
0.075
0.070
0.066
5
-
0.173
0.125
0.101
0.086
0.076
0.068
0.062
0.057
0.053
0.049
0.046
0.044
10
-
-
0.093
0.076
0.066
0.058
0.053
0.048
0.045
0.042
0.039
0.037
0.035
15
-
-
-
0.063
0.055
0.049
0.045
0.041
0.038
0.036
0.034
0.032
0.030
20
-
-
-
-
0.048
0.043
0.039
0.036
0.034
0.032
0.030
0.028
0.027
25
-
-
-
-
-
0.039
0.035
0.033
0.031
0.029
0.027
0.026
0.025
30
-
-
-
-
-
-
0.032
0.030
0.028
0.026
0.025
0.024
0.023
35
-
-
-
-
-
-
-
0.028
0.026
0.025
0.023
0.022
0.021
40
-
-
-
-
-
-
-
-
0.025
0.023
0.022
0.021
0.020
45
-
-
-
-
-
-
-
-
-
0.022
0.021
0.020
0.019
50
-
-
-
-
-
-
-
-
-
-
0.020
0.019
0.018
55
-
-
-
-
-
-
-
-
-
-
-
0.018
0.017
60
-
-
-
-
-
-
-
-
-
-
-
-
0.016
Table A102.2.6(2)
Assembly U-factors for Roofs with Tapered Insulation Entirely Above Deck Sloped Triangle (Roof with Center Drain)e,f,g,h,i
(Uninterrupted by Framing)
 
Rated R-value of Insulation at Maximum Condition (Rmaxc)
1
5
10
15
20
25
30
35
40
45
50
55
60
Rated R-value of insulation at a Minimum Condition (Rminb)
1
0.526
0.242
0.146
0.106
0.083
0.068
0.058
0.051
0.045
0.040
0.036
0.033
0.031
5
-
0.173
0.112
0.084
0.068
0.057
0.049
0.044
0.039
0.035
0.032
0.030
0.028
10
-
-
0.093
0.071
0.059
0.050
0.044
0.039
0.035
0.032
0.029
0.027
0.025
15
-
-
-
0.063
0.053
0.045
0.040
0.035
0.032
0.029
0.027
0.025
0.023
20
-
-
-
-
0.048
0.042
0.037
0.033
0.030
0.027
0.025
0.024
0.022
25
-
-
-
-
-
0.039
0.034
0.031
0.028
0.026
0.024
0.022
0.021
30
-
-
-
-
-
-
0.032
0.029
0.027
0.025
0.023
0.021
0.020
35
-
-
-
-
-
-
-
0.028
0.026
0.024
0.022
0.021
0.019
40
-
-
-
-
-
-
-
-
0.025
0.023
0.021
0.020
0.019
45
-
-
-
-
-
-
-
-
-
0.022
0.020
0.019
0.018
50
-
-
-
-
-
-
-
-
-
-
0.020
0.018
0.017
55
-
-
-
-
-
-
-
-
-
-
-
0.018
0.017
60
-
-
-
-
-
-
-
-
-
-
-
-
0.016
Table A102.2.6(3)
Assembly U-factors for Roofs with Tapered Insulation Entirely Above Deck Sloped Triangle (Roof with Perimeter Drains)e,f,g,h,i
(Uninterrupted by Framing)
 
Rated R-value of Insulation at Maximum Condition (Rmaxc)
1
5
10
15
20
25
30
35
40
45
50
55
60
Rated R-value of insulation at a Minimum Condition (Rminb)
1
0.562
0.242
0.146
0.106
0.083
0.068
0.058
0.051
0.045
0.040
0.036
0.033
0.031
5
-
0.173
0.122
0.084
0.068
0.057
0.049
0.044
0.039
0.035
0.032
0.030
0.028
10
-
-
0.093
0.071
0.059
0.050
0.044
0.039
0.035
0.032
0.029
0.027
0.025
15
-
-
-
0.063
0.053
0.045
0.040
0.035
0.032
0.029
0.027
0.025
0.024
20
-
-
-
-
0.048
0.042
0.037
0.033
0.030
0.027
0.025
0.024
0.022
25
-
-
-
-
-
0.039
0.034
0.031
0.028
0.026
0.024
0.022
0.021
30
-
-
-
-
-
-
0.032
0.029
0.027
0.025
0.023
0.021
0.020
35
-
-
-
-
-
-
-
0.028
0.026
0.024
0.022
0.021
0.019
40
-
-
-
-
-
-
-
-
0.025
0.023
0.021
0.020
0.019
45
-
-
-
-
-
-
-
-
-
0.022
0.020
0.019
0.018
50
-
-
-
-
-
-
-
-
-
-
0.020
0.018
0.017
55
-
-
-
-
-
-
-
-
-
-
-
0.018
0.017
60
-
-
-
-
-
-
-
-
-
-
-
-
0.016
Footnotes to Tables A102.2.6(1), A102.2.6(2), and A102.2.6(3):
 
a Rmax and Rmin are determined along the linearly tapered cross section for the 6. respective minimum and maximum thickness values for the roof section being analyzed. For triangular roof sections.
 
b Rmax refers to the insulation value along the long edge of the triangle and Rmin to the insulation at the point of the triangle which assumes that the insulation slopes to the center.
 
c Rmax refers to the insulation value at the point of the triangle and Rmin to the insulation along the long edge of the triangle which assumes that the insulation slopes to the perimeter.
 
d Effective U-factor for rectangular tapered insulation is calculated as follows:
Reff
=
Rmax – Rmin
Ln[Rmax/Rmin]
 
e Effective U-factor for triangular tapered insulation is calculated as follows:
 
Reff = [2/(Rmax – Rmin) [1 + (Rmin/Rmax – Rmin)ln(Rmin/Rmax)]]-1
 
f Assembly U-factors include an exterior air film (R=0.17) and an interior air film, horizontal with heat flow up (R=0.61).
 
g For effective U-factors of roof assemblies with different Rmax or Rmin values not listed in the tables interpolation is allowed.
 
h This table shall only be applied to tapered insulation that is tapered along only one axis.
 
i In areas of differing insulation slopes/configurations, individual U-values shall be calculated and an area weighted U-value calculation shall be used to determine the effective value of the roof.
[Statutory Authority: RCW 19.27A.025, 19.27A.160, and 19.27.074. WSR 16-03-072, § 51-11C-610226, filed 1/19/16, effective 7/1/16. Statutory Authority: RCW 19.27A.020, 19.27A.025 and chapters 19.27 and 34.05 RCW. WSR 13-04-056, § 51-11C-610226, filed 2/1/13, effective 7/1/13.]
Reviser's note: The brackets and enclosed material in the text of the above section occurred in the copy filed by the agency.