figure 2-12F

Figure 2-12F. Concrete Masonry Basement Wall with Exterior Insulation, Footing Detail

figure 2-12S

Figure 2-12S. Concrete Masonry Basement Wall with Exterior Insulation, Sill Detail

Figures 2-12S and 2-12F illustrate a concrete masonry foundation wall with exterior insulation. An external insulation approach is recommended on concrete masonry walls unless all cores are grouted solid.  Alternately, cores can be filled with insulating material such as perlite or polystyrene inserts. This may be effective in minimizing convection within the cores which may improve moisture performance, but it is a poor method of insulating because of the strong thermal shorts through the CMU webbing.  Additional interior rim insulation is provided with approved foil-faced polyisocyanurate, which may not require flame-resistant coverings in some jurisdictions.