What is the R-value of foam insulation?

The R-value of foam insulation ranges between R-4 to R-6.5 per inch of thickness. Open-cell insulation has a value of R-3.7 while closed-cell insulation's value is R-6.2.

When the right R-value, it is necessary to consider climate of an area, budget of the project and home design. Foam insulation that has a higher R-value should be used in cathedral ceilings and exterior walls. Usually, closed-cell foam insulation has a higher R-value and helps to protect the house against air leakage and moisture. However, it is more costly to buy and install, but the benefits are long lasting. Open-cell usually have low R-value and they tend to be filled with air.