Climate zones by state

North Carolina Climate Zones by County

North Carolina's 100 counties span climate zones 3A to 5A under the 2021 International Energy Conservation Code (IECC). Zone 3A is the most common, with 79 of the 100. For reference, Wilmington, Charlotte and Raleigh are in zone 3A and Asheville is in 4A.

Insulation minimums for each zone in North Carolina

ZoneCountiesAtticWood-frame wallsFloors over unheated spaceBasement walls
3A79R-49R-20, or 13+5ci, or R-15ciR-19R-5ci or R-13
4A16R-60R-30, or 20+5ci, or 13+10ci, or R-20ciR-19R-10ci or R-13
5A5R-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 North Carolina uses

North Carolina enforces the 2015 IECC with amendments for homes (in effect since Jan 2019). 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

34 counties moved one zone warmer in the 2021 map: Alamance County (4 → 3), Alexander County (4 → 3), Bertie County (4 → 3), Caswell County (4 → 3), Catawba County (4 → 3), Chatham County (4 → 3), Cherokee County (4 → 3), Clay County (4 → 3), Cleveland County (4 → 3), Davie County (4 → 3), Durham County (4 → 3), Forsyth County (4 → 3), and 22 more marked in the table below. If your town still enforces the 2018 or 2015 code, the older zone applies to permits.

Every county in North Carolina

NameZone (2021)Zone (2018)Details
Alamance County3A4A changedInsulation →
Alexander County3A4A changedInsulation →
Alleghany County5A5AInsulation →
Anson County3A3AInsulation →
Ashe County5A5AInsulation →
Avery County5A5AInsulation →
Beaufort County3A3AInsulation →
Bertie County3A4A changedInsulation →
Bladen County3A3AInsulation →
Brunswick County3A3AInsulation →
Buncombe County4A4AInsulation →
Burke County4A4AInsulation →
Cabarrus County3A3AInsulation →
Caldwell County4A4AInsulation →
Camden County3A3AInsulation →
Carteret County3A3AInsulation →
Caswell County3A4A changedInsulation →
Catawba County3A4A changedInsulation →
Chatham County3A4A changedInsulation →
Cherokee County3A4A changedInsulation →
Chowan County3A3AInsulation →
Clay County3A4A changedInsulation →
Cleveland County3A4A changedInsulation →
Columbus County3A3AInsulation →
Craven County3A3AInsulation →
Cumberland County3A3AInsulation →
Currituck County3A3AInsulation →
Dare County3A3AInsulation →
Davidson County3A3AInsulation →
Davie County3A4A changedInsulation →
Duplin County3A3AInsulation →
Durham County3A4A changedInsulation →
Edgecombe County3A3AInsulation →
Forsyth County3A4A changedInsulation →
Franklin County3A4A changedInsulation →
Gaston County3A3AInsulation →
Gates County3A4A changedInsulation →
Graham County4A4AInsulation →
Granville County3A4A changedInsulation →
Greene County3A3AInsulation →
Guilford County3A4A changedInsulation →
Halifax County3A4A changedInsulation →
Harnett County3A4A changedInsulation →
Haywood County4A4AInsulation →
Henderson County4A4AInsulation →
Hertford County3A4A changedInsulation →
Hoke County3A3AInsulation →
Hyde County3A3AInsulation →
Iredell County3A4A changedInsulation →
Jackson County4A4AInsulation →
Johnston County3A3AInsulation →
Jones County3A3AInsulation →
Lee County3A4A changedInsulation →
Lenoir County3A3AInsulation →
Lincoln County3A4A changedInsulation →
Macon County4A4AInsulation →
Madison County4A4AInsulation →
Martin County3A3AInsulation →
McDowell County4A4AInsulation →
Mecklenburg County3A3AInsulation →
Mitchell County4A5A changedInsulation →
Montgomery County3A3AInsulation →
Moore County3A3AInsulation →
Nash County3A4A changedInsulation →
New Hanover County3A3AInsulation →
Northampton County3A4A changedInsulation →
Onslow County3A3AInsulation →
Orange County3A4A changedInsulation →
Pamlico County3A3AInsulation →
Pasquotank County3A3AInsulation →
Pender County3A3AInsulation →
Perquimans County3A3AInsulation →
Person County3A4A changedInsulation →
Pitt County3A3AInsulation →
Polk County3A4A changedInsulation →
Randolph County3A3AInsulation →
Richmond County3A3AInsulation →
Robeson County3A3AInsulation →
Rockingham County3A4A changedInsulation →
Rowan County3A3AInsulation →
Rutherford County3A4A changedInsulation →
Sampson County3A3AInsulation →
Scotland County3A3AInsulation →
Stanly County3A3AInsulation →
Stokes County4A4AInsulation →
Surry County4A4AInsulation →
Swain County4A4AInsulation →
Transylvania County4A4AInsulation →
Tyrrell County3A3AInsulation →
Union County3A3AInsulation →
Vance County3A4A changedInsulation →
Wake County3A4A changedInsulation →
Warren County3A4A changedInsulation →
Washington County3A3AInsulation →
Watauga County5A5AInsulation →
Wayne County3A3AInsulation →
Wilkes County3A4A changedInsulation →
Wilson County3A3AInsulation →
Yadkin County4A4AInsulation →
Yancey County5A5AInsulation →

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 North Carolina?

North Carolina spans IECC climate zones 3A to 5A; zone 3A is the most common. Find your county in the table above, or search by ZIP code.

How much attic insulation do I need in North Carolina?

In North Carolina, the 2021 IECC calls for R-49 and R-60 in the attic, depending on the zone. The table near the top of this page lists each zone's minimums.

What energy code does North Carolina use?

North Carolina enforces the 2015 IECC with amendments for homes (in effect since Jan 2019). Source: US Department of Energy, September 2026. Local governments can adopt newer codes or amendments.

More for North Carolina: Last frost dates in North Carolina · North Carolina planting zones · Frost line depth by state