Closed-cell foam insulation typically provides about R-5.8 to R-6.9 per inch, depending on the product and its tested thermal performance. The U.S. Department of Energy's Building America guidance lists aged closed-cell spray foam at about R-6.1 per inch, while EPA describes professional closed-cell SPF as having an R-value around R-6.5 per inch.
For residential applications in Alpine, WY,...
