PDFWAC 51-11C-610225

Tables A102.2.5Default U-factors for metal building roofs.

Table A102.2.5
Default U-factors for Metal Building Roofs
 
 
 
Overall U-Factor for Assembly of Base Roof Plus Continuous
Insulation (uninterrupted by framing) Rated R-Value of
Continuous Insulation
Insulation
System
Rated R-Value of
Insulation
Overall U-Factor for Entire Base Roof
Assembly
R-6.5
R-13
R-19.5
R-26
R-32.5
R-39
Standing Seam Roofs with Thermal Spacer Blocksa, b
 
None
1.280
0.137
0.073
0.049
0.037
0.030
0.025
 
R-10
0.115
0.066
0.046
0.035
0.029
0.024
0.021
Single
R-11
0.107
0.063
0.045
0.035
0.028
0.024
0.021
Layer
R-13
0.101
0.061
0.044
0.034
0.028
0.024
0.020
 
R-16
0.096
0.059
0.043
0.033
0.027
0.023
0.020
 
R-19
0.082
0.053
0.040
0.031
0.026
0.022
0.020
 
R-10 + R-10
0.088
0.056
0.041
0.032
0.027
0.023
0.020
 
R-10 + R-11
0.086
0.055
0.041
0.032
0.027
0.023
0.020
 
R-11 + R-11
0.085
0.055
0.040
0.032
0.026
0.023
0.020
 
R-10 + R-13
0.084
0.054
0.040
0.032
0.026
0.023
0.020
Double
R-11 + R-13
0.082
0.053
0.040
0.032
0.026
0.022
0.020
Layer
R-13 + R-13
0.075
0.050
0.038
0.030
0.025
0.022
0.019
 
R-10 + R-19
0.074
0.050
0.038
0.030
0.025
0.022
0.019
 
R-11 + R-19
0.072
0.049
0.037
0.030
0.025
0.022
0.019
 
R-13 + R-19
0.068
0.047
0.036
0.029
0.025
0.021
0.019
 
R-16 + R-19
0.065
0.046
0.035
0.029
0.024
0.021
0.018
 
R-19 + R-19
0.060
0.043
0.034
0.028
0.023
0.020
0.018
Liner
R-19 + R-11
0.035
 
 
 
 
 
 
System
R-25 + R-11
0.031
 
 
 
 
 
 
 
R-30 + R-11
0.029
 
 
 
 
 
 
 
R-25 + R-11 + R-11
0.026
 
 
 
 
 
 
Filled Cavity with Thermal Spacer Blocksc
 
R-10 + R-19
0.057
0.042
0.033
0.027
0.023
0.020
0.018
Standing Seam Roofs without Thermal Spacer Blocks
Liner
System
R-19 + R-11
0.040
 
 
 
 
 
 
Thru-Fastened Roofs without Thermal Spacer Blocks
Single
R-10
0.184
 
 
 
 
 
 
Layer
R-11
0.182
 
 
 
 
 
 
 
R-13
0.174
 
 
 
 
 
 
 
R-16
0.157
 
 
 
 
 
 
 
R-19
0.151
 
 
 
 
 
 
Liner System
R-19 + R-11
0.044
 
 
 
 
 
 
 
(Multiple R-values are listed in order from inside to outside)
a
A standing seam roof clip that provides a minimum 1.5 inch distance between the top of the purlins and the underside of the metal roof panels is required.
b
A minimum R-3 thermal spacer block is required.
c
A minimum R-5 thermal spacer block is required.
[Statutory Authority: RCW 19.27A.020, 19.27A.025 and chapters 19.27 and 34.05 RCW. WSR 13-04-056, § 51-11C-610225, filed 2/1/13, effective 7/1/13.]