IECC Climate Zone Map
Find your climate zone to understand insulation requirements. Click the map or enter your ZIP code for accurate R-value recommendations.
IECC Climate Zone Map
Click on a zone to see its R-value requirements, or enter your ZIP code below.
Find Your Zone
Enter your ZIP code for the most accurate climate zone.
Or select zone:
Understanding IECC Climate Zones
What Are Climate Zones?
The International Energy Conservation Code (IECC) divides the United States into 8 climate zones based on temperature patterns, heating degree days (HDD), and cooling degree days (CDD). These zones determine minimum insulation requirements for buildings.
The 8 Climate Zones
| Zone | Climate Type | Example Locations |
|---|---|---|
| 1 | Very Hot-Humid | Hawaii, Puerto Rico, Key West FL |
| 2 | Hot-Humid | South Florida, South Texas, Phoenix AZ |
| 3 | Warm / Mixed-Humid | Atlanta GA, Los Angeles CA, Dallas TX |
| 4 | Mixed-Humid | Washington DC, Nashville TN, Seattle WA |
| 5 | Cold | Chicago IL, Denver CO, Boston MA |
| 6 | Cold (Severe) | Minneapolis MN, Burlington VT, Boise ID |
| 7 | Very Cold | Anchorage AK, Duluth MN |
| 8 | Subarctic | Fairbanks AK, Northern Alaska |
Why Climate Zones Matter
Your climate zone directly determines how much insulation your home needs. Colder zones (5-8) require significantly higher R-values to prevent heat loss in winter, while warmer zones (1-3) focus on reducing cooling loads and may benefit more from radiant barriers.
Zone Boundary Variations
Climate zones can vary within a single state, especially in mountainous regions. For example, Colorado has areas in Zones 4, 5, 6, and 7 depending on elevation. Always verify your specific zone with local building officials.
Heating vs. Cooling Dominant Climates
Heating-dominant (Zones 4-8): Focus on preventing heat loss. Higher R-values in attics and walls are critical. Air sealing provides the best ROI.
Cooling-dominant (Zones 1-3): Focus on reducing heat gain. Radiant barriers in attics can be very effective. Proper ventilation and reflective materials matter more.
Related Resources
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Insulation Quiz
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Frequently Asked Questions
My area seems to be on a zone boundary. Which zone should I use?
If you're on a zone boundary, using the higher (colder) zone number is generally the safer choice — you'll end up with more insulation, which won't hurt performance. However, for building permits, always check with your local building department for the official zone designation.
Do climate zones change over time?
The IECC updates its climate zone map periodically (typically every 3 years with code updates). Climate change may shift some zone boundaries over decades. However, for current building projects, use the most recent IECC edition adopted by your jurisdiction.
What about humid vs. dry designations (A, B, C)?
The full IECC zone system includes moisture designations: A (moist), B (dry), and C (marine). For example, Zone 3A (humid Southeast) vs 3B (dry Southwest). These affect vapor barrier requirements more than R-values, but both use the same insulation R-value minimums.
My state has its own energy code. Should I use that instead?
Yes! Many states adopt modified versions of the IECC or have their own energy codes (like California's Title 24). State and local codes supersede the model IECC requirements. This map shows IECC zones as a baseline — always verify with local requirements before starting a project.