Foam insulation is available in spray-in-place systems as well as rigid boards. Spray-in-place foams have very high insulating R-values. For example, spray polyurethane foam has an Rvalue range of between R-5.6 to R-6.3 per inch of thickness. The spray equipment requires skilled workers to operate. Common spray-in-place foams include polyurethane foam, urea-formaldehyde (UF) foam, and phenolic foam. These foam insulations expand and set almost immediately after their application. They will eventually shrink and settle in the wall cavities, but their shrinkage should be not more than 5 percent if they are properly applied.
Foam insulation is flammable and requires a fireproof covering material if it is installed on the interior of a structure.