Section A104.1—General.
A104.1 General. Table A104.1 lists heat loss coefficients for below-grade walls and floors.
Coefficients for below-grade walls are given as U-factors (Btu/h • ft2 • °F of wall area). Coefficients for below-grade slabs are listed as F-factors (Btu/h • ft • °F per lineal foot of slab perimeter).
Below-grade wall U-factors are only valid when used with the accompanying below-grade slab F-factor, and vice versa.
Table A104.1
Default Wall U-factors and Slab F-factors for Basements
| Below Grade Wall U-factor | Below Grade Slab F-factor |
2 Foot Depth Below Grade |
Uninsulated | 0.350 | 0.59 |
R-11 Interior | 0.066 | 0.68 |
R-11 Interior w/TB | 0.070 | 0.60 |
R-19 Interior | 0.043 | 0.69 |
R-19 Interior w/TB | 0.045 | 0.61 |
R-10 Exterior | 0.070 | 0.60 |
R-12 Exterior | 0.061 | 0.60 |
3.5 Foot Depth Below Grade |
Uninsulated | 0.278 | 0.53 |
R-11 Interior | 0.062 | 0.63 |
R-11 Interior w/TB | 0.064 | 0.57 |
R-19 Interior | 0.041 | 0.64 |
R-19 Interior w/TB | 0.042 | 0.57 |
R-10 Exterior | 0.064 | 0.57 |
R-12 Exterior | 0.057 | 0.57 |
7 Foot Depth Below Grade |
Uninsulated | 0.193 | 0.46 |
R-11 Interior | 0.054 | 0.56 |
R-11 Interior w/TB | 0.056 | 0.42 |
R-19 Interior | 0.037 | 0.57 |
R-19 Interior w/TB | 0.038 | 0.43 |
R-10 Exterior | 0.056 | 0.42 |
R-12 Exterior | 0.050 | 0.42 |