What is R-Value?
R-value measures the resistance to heat flow. The higher the number, the better the material is at insulating.
Common Material R-Values (per inch)
- Fiberglass Batts: R-3.0 to R-3.8
- Blown Cellulose: R-3.2 to R-3.8
- Rigid Foam (Polyiso): R-6.0 to R-6.5
Regional Requirements
If you live in a cold climate (like Minnesota), you might need R-49 in your attic. In a warm climate (like Florida), R-30 might be enough.
Key Takeaways
- R-values are additive (two R-10 layers = R-20)
- Gaps and compression reduce actual R-value
- Air sealing is just as important as insulation