R-Value is a measure of insulation’s ability to resist heat passing through it.

The higher the R-Value the better the thermal performance of the insulation.  R-Value is a number given “per inch of thickness”.  For example, an insulation type with an R-Value of 5 means “5 per inch of thickness”.  Therefore, a 1” thick layer would have an R-Value of 5; a 2” thick layer an R-Value of 10 and so on.  Thickness matters!

Learn more about the R-Value of each of the 3 types of insulation – XPS, EPS, ISO.

US Department of Energy R-Value recommendations by climate zone. 

DOE R-Value recommendations by climate zone map

Insulation Recommendations for New Wood-Framed Houses

*Note: In the table above, CI stands for “continuous insulation” that is applied to the exterior of the wall assembly just inside the cladding.

Reference: US Department of Energy 2021 https://www.energy.gov/energysaver/insulation