- The insulation within a cavity wall is often interrupted at the parapet, with the roof insulation stopping on one side of the interior wythe of the parapet and the cavity wall insulation stopping at the roof line. This creates a cold spot. What can be done to avoid this?
Heat loss through parapets can be a significant problem, especially in very cold climates, since the parapet is exposed to exterior air on both sides. If the insulation in the cavity wall stops at the roof structure and the roof insulation stops on the roof side of the parapet, there will be several heat flow paths.
One way to avoid the problem in parapets less than 30 inches tall, where the inside face will be covered with roofing, is to extend the cavity wall insulation up to the top of the parapet and extend the roof insulation up the interior face of the parapet. For taller parapets, the insulation on the roof side of the parapet can be covered with a metal panel system or some other lightweight wall system.