Spray foam insulation R-Values range from R-3.6 to R-7 per inch, depending on the type and manufacturer. Open cell foam offers R-3.6 to R-3.9 per inch, while closed cell foam provides a higher R-5.5 to R-7 per inch for superior thermal resistance.
1. High-Density 2. Medium-Density 3. Low-Density
There are a couple of main issues with spray foam and R-values. The first is just like some of the companies selling bubble wrap insulation, they have been known to be deceptive.
When you look at the charts comparing spray foam insulation R-values, you would think since closed-cell foam has the highest r-value, it is the best choice. Open-cell foam being R-3.6 and closed-cell R-5.5 per inch.