Map of the IECC climate zones across the United States, with climate zone 4 highlighted

IECC climate zones run from warm zone 1 in the south to cold zone 8 in the north. Find your zone — the colder it is, the higher the insulation R-value the code requires.

A simplified map of the United States colored by IECC climate zone, from warm zone 1 in the south (red) to cold zone 8 in the far north (navy). Florida and the Gulf coast fall in the hot zones 1 and 2; the deep South in warm zone 3; the middle of the country in mixed zone 4 and cool zone 5; and the northern tier, including Minnesota and Maine, in the cold zones 6 and 7. A legend names each zone’s climate. Climate zone 4 (mixed) is highlighted, because a colder zone requires a higher insulation R-value. The figure also lists example cities in the highlighted zone and the IECC minimum insulation R-values for the attic, walls, and floor. — Source: 2021 IECC Figure R301.1 / Table R301.1

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A simplified map of the United States colored by IECC climate zone, from warm zone 1 in the south (red) to cold zone 8 in the far north (navy). Florida and the Gulf coast fall in the hot zones 1 and 2; the deep South in warm zone 3; the middle of the country in mixed zone 4 and cool zone 5; and the northern tier, including Minnesota and Maine, in the cold zones 6 and 7. A legend names each zone’s climate. Climate zone 4 (mixed) is highlighted, because a colder zone requires a higher insulation R-value. The figure also lists example cities in the highlighted zone and the IECC minimum insulation R-values for the attic, walls, and floor.

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    <img src="https://remodelcalculators.com/api/figure-embed/iecc-zone-map" alt="A simplified map of the United States colored by IECC climate zone, from warm zone 1 in the south (red) to cold zone 8 in the far north (navy). Florida and the Gulf coast fall in the hot zones 1 and 2; the deep South in warm zone 3; the middle of the country in mixed zone 4 and cool zone 5; and the northern tier, including Minnesota and Maine, in the cold zones 6 and 7. A legend names each zone’s climate. Climate zone 4 (mixed) is highlighted, because a colder zone requires a higher insulation R-value. The figure also lists example cities in the highlighted zone and the IECC minimum insulation R-values for the attic, walls, and floor." width="800" height="600" style="width:100%;height:auto;border:0" loading="lazy">
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    Diagram: <a href="https://remodelcalculators.com/construction-diagrams/iecc-zone-map" target="_blank" rel="noopener">Map of the IECC climate zones across the United States, with climate zone 4 highlighted</a> — courtesy of <a href="https://remodelcalculators.com" target="_blank" rel="noopener">RemodelCalculators.com</a>
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Read the guide: Iecc Climate Zone 4