Floors over unheated areas, such as garages, may only use those values which have R 0 perimeter insulation. The crawlspace is not actively heated. Floors over unheated basements may only use those values which have R 0 perimeter insulation. Heated supply air from central furnace is blown into a crawlspace and allowed to enter the living space unducted via holes cut into the floor. Insulation is assumed to be installed under the subflooring between the joists or beams with no space between the insulation and the subfloor.
Insulation is assumed to be uncompressed.
Exposed floors also include concrete with continuous rigid insulation assumed. Floor coverings are assumed to be light carpet with rubber pad. Default U factors in Table 10-4 reflect this higher rate of heat loss. DCLU moved to Key Tower in Spring 2001.