IECC minimum attic and wall R-values across all eight climate zones

The colder your zone, the more insulation the code requires — attic minimums climb from R-30 to R-60 and walls from R-13 to R-30, then plateau in the coldest zones.

A bar chart of the 2021 IECC prescriptive minimum insulation R-values for the attic and the exterior wall across all eight climate zones. The attic minimum rises from R-30 in zone 1 to R-49 in zones 2 and 3 and R-60 in zones 4 through 8. The wall minimum rises from R-13 in zones 1 and 2 to R-20 in zone 3 and R-30 in zones 4 through 8. Requirements climb steeply through the warm and mixed zones, then plateau in the cold northern zones. This is why looking up your climate zone is the first step in any insulation or envelope job. — Source: 2021 IECC Table R402.1.3

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A bar chart of the 2021 IECC prescriptive minimum insulation R-values for the attic and the exterior wall across all eight climate zones. The attic minimum rises from R-30 in zone 1 to R-49 in zones 2 and 3 and R-60 in zones 4 through 8. The wall minimum rises from R-13 in zones 1 and 2 to R-20 in zone 3 and R-30 in zones 4 through 8. Requirements climb steeply through the warm and mixed zones, then plateau in the cold northern zones. This is why looking up your climate zone is the first step in any insulation or envelope job.

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    <img src="https://remodelcalculators.com/api/figure-embed/climate-zone-rvalue-ladder" alt="A bar chart of the 2021 IECC prescriptive minimum insulation R-values for the attic and the exterior wall across all eight climate zones. The attic minimum rises from R-30 in zone 1 to R-49 in zones 2 and 3 and R-60 in zones 4 through 8. The wall minimum rises from R-13 in zones 1 and 2 to R-20 in zone 3 and R-30 in zones 4 through 8. Requirements climb steeply through the warm and mixed zones, then plateau in the cold northern zones. This is why looking up your climate zone is the first step in any insulation or envelope job." width="800" height="500" style="width:100%;height:auto;border:0" loading="lazy">
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    Diagram: <a href="https://remodelcalculators.com/construction-diagrams/climate-zone-rvalue-ladder" target="_blank" rel="noopener">IECC minimum attic and wall R-values across all eight climate zones</a> — courtesy of <a href="https://remodelcalculators.com" target="_blank" rel="noopener">RemodelCalculators.com</a>
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