Recommended Home Insulation R–Values
Insulation levels are specified by R-Value. R-Value is a measure of insulation’s ability to resist heat traveling through it. The higher the R-Value the better the thermal performance of the insulation. The table below shows what levels of insulation are cost-effective for different climates and locations in the home.
Recommended insulation levels for retrofitting existing wood-framed buildings
![US map showing recommended insulation levels for retrofitting existing wood-framed buildings](/https/www.energystar.gov/sites/default/files/assets/images/insulations_map_updated.jpg)
Zone | Add Insulation to Attic | Floor | |
---|---|---|---|
If your attic is uninsulated | If you already have 3–4 inches of insulation | ||
1 | R30 | R25 | R13 |
2 | R49 | R38 | R13 |
3 | R49 | R38 | R19 |
4A and 4B | R60 | R49 | R19 |
6, 5, and 4C | R60 | R49 | R30 |
7 and 8 | R60 | R49 | R38 |
Wall Insulation (above the ground) - Whenever exterior siding is removed on an: Uninsulated wood-frame wall:
OR Insulated 2x4 wood-frame wall:
Basement or Crawlspace Wall Insulation:
Note: This guidance is based on the 2021 International Energy Conservation Code (IECC) Residential Provisions Chapter 4 Table R402.1.3. See Code for more detailed guidance. |