Washington Administrative Code › Title 51 - Enterprise Services, Department of (Building Code Council) › Chapter 51-11C - State Building Code adoption and amendment of the 2021 edition of the International Energy Conservation Code, Commercial › Section 51-11C-610226 - Tables A102.2.6-Assembly U-factors for roofs with insulation entirely above deck

Current through Register Vol. 24-14, July 15, 2024
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)
(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
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
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:
e Effective U-factor for triangular
				tapered insulation is calculated as follows:
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.
Reviser's note:
The brackets and enclosed
				  material in the text of the above section occurred in the copy filed by the
				  agency and appear in the Register pursuant to the requirements of RCW
				    34.08.040.
Statutory Authority:
				  RCW
				    19.27A.020,
				  19.27A.025 and
				  chapters
				  19.27 and
				  34.05 RCW. 13-04-056, §
				  51-11C-610226, filed 2/1/13, effective
				  7/1/13.