PDFWAC 51-11C-610211

Table A102.1Default U-factors for ceilings.

Table A102.1
Default U-factors for Ceilings
 
Standard Frame
Advanced Frame
Ceilings Below Vented Attics
 
 
Flat
Baffled
 
R-19
0.049
0.047
 
R-30
0.036
0.032
 
R-38
0.031
0.026
 
R-49
0.027
0.020
 
R-60
0.025
0.017
Scissors Truss
 
 
 
R-30 (4/12 roof pitch)
0.043
0.031
 
R-38 (4/12 roof pitch)
0.040
0.025
 
R-49 (4/12 roof pitch)
0.038
0.020
 
R-30 (5/12 roof pitch)
0.039
0.032
 
R-38 (5/12 roof pitch)
0.035
0.026
 
R-49 (5/12 roof pitch)
0.032
0.020
Vaulted Ceilings
16" O.C.
24" O.C.
 
Vented
 
 
 
 
R-19 2x10 joist
0.049
0.048
 
R-30 2x12 joist
0.034
0.033
 
R-38 2x14 joist
0.027
0.027
 
Unvented
 
 
 
 
R-30 2x10 joist
0.034
0.033
 
R-38 2x12 joist
0.029
0.027
 
R-21 + R-21 2x12 joist
0.026
0.025
Roof Deck
4 x Beams, 48" O.C.
R-12.5
2"
Rigid insulation
0.064
R-21.9
3.5"
Rigid insulation
0.040
R-37.5
6"
Rigid insulation
0.025
R-50
8"
Rigid insulation
0.019
[Statutory Authority: RCW 19.27A.020, 19.27A.025 and chapters 19.27 and 34.05 RCW. WSR 13-04-056, § 51-11C-610211, filed 2/1/13, effective 7/1/13.]