Marshall County is in IECC Climate Zone 3A (Warm - Humid). Get accurate Manual J load calculations with official ASHRAE design temperatures for Marshall County.
Marshall County, Alabama is classified under IECC Climate Zone 3A (Warm - Humid), a mixed-climate region with humid moisture conditions. With 10 ZIP codes and 1 communities, every HVAC installation in Marshall County must use the ASHRAE design temperatures of 20°F (99% winter heating) and 93°F (1% summer cooling) for accurate Manual J load calculations.
With balanced heating and cooling loads, Marshall County homes require well-rounded insulation — R-20 walls, R-30 ceilings, R-19 floors — and windows with both U-factor 0.32 and SHGC 0.25 to handle both winter lows and summer highs.
Minimum insulation R-values and window performance for Climate Zone 3A in Marshall County, AL.
| Building Component | Minimum Requirement | Unit |
|---|---|---|
| Ceiling / Attic Insulation | R-30 | R-value |
| Wall Insulation | R-20 | R-value |
| Floor Insulation | R-19 | R-value |
| Window U-Factor | 0.32 | BTU/hr-ft²-°F |
| Window SHGC | 0.25 | Coefficient |
| Air Infiltration | 0.15 | ACH50 |
Climate Zone 3A requires precise load calculations. Upload your Marshall County blueprint and get a professional Manual J report in 60 seconds— first report is FREE. Pre-loaded with Marshall County's exact design temperatures (20°F winter / 93°F summer).
Enter your ZIP code to confirm it's in Marshall County and get climate zone details.
Official ASHRAE design temperatures for Marshall County, AL, used for accurate Manual J load calculations.
Minimum insulation and window requirements for Marshall County per IECC 2021 energy code.
Climate Zone 3A: Warm - Humid - Mixed climate with warm, humid summers and cool winters. Balanced heating and cooling needs.
1 cities and communities in Marshall County share Climate Zone 3A requirements.
Compare climate zones with other counties in Alabama. Different zones require different HVAC equipment sizing.
Upload your Marshall County blueprint and get a professional Manual J load calculation using official Zone 3A design temperatures. First report is FREE.
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