Climate zones by state

West Virginia Climate Zones by County

West Virginia's 55 counties span climate zones 4A to 5A under the 2021 International Energy Conservation Code (IECC). Zone 4A is the most common, with 36 of the 55. For reference, Charleston and Huntington are in zone 4A and Morgantown is in 5A.

Insulation minimums for each zone in West Virginia

ZoneCountiesAtticWood-frame wallsFloors over unheated spaceBasement walls
4A36R-60R-30, or 20+5ci, or 13+10ci, or R-20ciR-19R-10ci or R-13
5A19R-60R-30, or 20+5ci, or 13+10ci, or R-20ciR-30R-15ci, or R-19, or 13+5ci

Minimums from the 2021 IECC (Table R402.1.3). Many areas still enforce an older edition, so check with your local building department. See sources.

Which energy code West Virginia uses

West Virginia enforces the 2015 IECC with amendments for homes (in effect since Aug 2022). Source: US Department of Energy, September 2026. Local governments can adopt newer codes or amendments. See every state's energy code.

What changed from the 2018 map

Nine counties moved one zone warmer in the 2021 map: Doddridge County (5 → 4), Fayette County (5 → 4), Greenbrier County (5 → 4), Lewis County (5 → 4), Nicholas County (5 → 4), Raleigh County (5 → 4), Summers County (5 → 4), Upshur County (5 → 4), Webster County (5 → 4). If your town still enforces the 2018 or 2015 code, the older zone applies to permits.

Every county in West Virginia

NameZone (2021)Zone (2018)Details
Barbour County5A5AInsulation →
Berkeley County4A4AInsulation →
Boone County4A4AInsulation →
Braxton County4A4AInsulation →
Brooke County5A5AInsulation →
Cabell County4A4AInsulation →
Calhoun County4A4AInsulation →
Clay County4A4AInsulation →
Doddridge County4A5A changedInsulation →
Fayette County4A5A changedInsulation →
Gilmer County4A4AInsulation →
Grant County5A5AInsulation →
Greenbrier County4A5A changedInsulation →
Hampshire County5A5AInsulation →
Hancock County5A5AInsulation →
Hardy County5A5AInsulation →
Harrison County5A5AInsulation →
Jackson County4A4AInsulation →
Jefferson County4A4AInsulation →
Kanawha County4A4AInsulation →
Lewis County4A5A changedInsulation →
Lincoln County4A4AInsulation →
Logan County4A4AInsulation →
Marion County5A5AInsulation →
Marshall County5A5AInsulation →
Mason County4A4AInsulation →
McDowell County4A4AInsulation →
Mercer County4A4AInsulation →
Mineral County5A5AInsulation →
Mingo County4A4AInsulation →
Monongalia County5A5AInsulation →
Monroe County4A4AInsulation →
Morgan County4A4AInsulation →
Nicholas County4A5A changedInsulation →
Ohio County5A5AInsulation →
Pendleton County5A5AInsulation →
Pleasants County4A4AInsulation →
Pocahontas County5A5AInsulation →
Preston County5A5AInsulation →
Putnam County4A4AInsulation →
Raleigh County4A5A changedInsulation →
Randolph County5A5AInsulation →
Ritchie County4A4AInsulation →
Roane County4A4AInsulation →
Summers County4A5A changedInsulation →
Taylor County5A5AInsulation →
Tucker County5A5AInsulation →
Tyler County4A4AInsulation →
Upshur County4A5A changedInsulation →
Wayne County4A4AInsulation →
Webster County4A5A changedInsulation →
Wetzel County5A5AInsulation →
Wirt County4A4AInsulation →
Wood County4A4AInsulation →
Wyoming County4A4AInsulation →

Source: Pacific Northwest National Laboratory, Guide to Determining Climate Zone by County: Building America and IECC 2021 Updates (2022).

Frequently asked questions

What climate zone is West Virginia?

West Virginia spans IECC climate zones 4A to 5A; zone 4A is the most common. Find your county in the table above, or search by ZIP code.

How much attic insulation do I need in West Virginia?

The 2021 IECC calls for R-60 in the attic everywhere in West Virginia.

What energy code does West Virginia use?

West Virginia enforces the 2015 IECC with amendments for homes (in effect since Aug 2022). Source: US Department of Energy, September 2026. Local governments can adopt newer codes or amendments.

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