IECC climate-zone target R-value by assembly
Typical published planning values — NOT a certified design. Real performance depends on installation quality, framing / thermal bridging, moisture and settling; follow the product data sheet and your local energy code. Foam ignition/thermal-barrier, vapor/moisture control and combustion-air safety are set by the manufacturer and code — check with a professional.
The IECC and ENERGY STAR publish recommended R-values by climate zone and assembly. The table below is labeled planning typicals — attic, wall-cavity and floor targets by zone 1–8. Confirm the current recommendation and your local energy code. Use it with the climate-zone target-R reference and the attic R by climate zone.
| IECC zone | Attic | Wall cavity | Floor |
|---|---|---|---|
| Zone 1 | R30–R49 | R13–R15 | R13–R13 |
| Zone 2 | R38–R49 | R13–R15 | R13–R13 |
| Zone 3 | R38–R49 | R13–R15 | R19–R19 |
| Zone 4 | R49–R60 | R13–R21 | R19–R30 |
| Zone 5 | R49–R60 | R13–R21 | R25–R30 |
| Zone 6 | R49–R60 | R19–R21 | R25–R30 |
| Zone 7 | R49–R60 | R19–R21 | R25–R30 |
| Zone 8 | R49–R60 | R19–R21 | R25–R30 |
Labeled IECC/ENERGY STAR planning typicals — confirm the current recommendation and your local energy code. Colder zones (higher numbers) call for more R; a wall band can also be met as R-13 cavity + continuous exterior foam.