figure 2-14F

Figure 2-14F. Concrete Basement Wall with Interior Insulation, Footing Detail

figure 2-14S

Figure 2-14S. Concrete Basement Wall with Interior Insulation, Sill Detail

Figures 2-14F and 2-14S show a basement wall insulated on the interior with rigid foam plastic.  In addition to covering the field of the wall, the foam is also cut to fit between joists at sill and rim joist.  Note that cutting, fitting, and sealing rigid insulation to fit between floor joists is labor-intensive.  Spray foam can be used at the rim as an alternate. The continuous layer of foam attached to the wall is covered by a thermal barrier of ½” paperless drywall.  This drywall is held away from the floor by ½” to avoid wicking of moisture from the floor.  Both the foam and the drywall should be sealed at all joints to eliminate pathways for air to reach the foundation wall.  Use only vapor-permeable latex paint as a finish.