Table A102.1—Default 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 |