A pony wall consists of a short wood frame wall sitting on top of a conventional concrete foundation. In this case, the wood frame section is insulated between the studs, and the concrete section is insulated on the interior (assuming there are no moisture problems). The insulation on the concrete is extended up about 200 mm (8 in.) to overlap with the frame section. A ledge is created at this point (see Figure 6-20). To avoid a ledge, install a frame wall from floor to ceiling and fill the cavity with insulation.

This method will offer higher thermal performance but creates a deep window frame.