XPS rigid foam board: R-value per inch
Short answer
XPS rigid foam board adds about R-5 per inch, so you need roughly 6.0" for R-30 and 9.8" for R-49.
R-value per inch
R-5
Best for
Foundation and below-grade walls
XPS rigid foam board thickness chart
| Target R-value | Thickness needed |
|---|---|
| R-13 | 2.6" |
| R-19 | 3.8" |
| R-30 | 6.0" |
| R-38 | 7.6" |
| R-49 | 9.8" |
| R-60 | 12.0" |
How much for your home?
Calculate xps rigid foam boardOther materials
Frequently asked questions
How many inches of xps rigid foam board do I need for R-49?
About 9.8" of xps rigid foam board, since it adds roughly R-5 per inch (R-49 ÷ 5).
What is the R-value of xps rigid foam board per inch?
XPS rigid foam board provides about R-5 per inch (a typical value — density and brand vary). So 6.0" gives roughly R-30.
What is xps rigid foam board best used for?
Foundation and below-grade walls. Compare it against other materials for your target R-value in the calculator.