Climate zones by state

South Carolina Climate Zones by County

South Carolina's 46 counties span climate zones 2A to 3A under the 2021 International Energy Conservation Code (IECC). Zone 3A is the most common, with 44 of the 46. For reference, Charleston, Columbia and Greenville are in zone 3A.

Insulation minimums for each zone in South Carolina

ZoneCountiesAtticWood-frame wallsFloors over unheated spaceBasement walls
2A2R-49R-13, or R-10ciR-13None required
3A44R-49R-20, or 13+5ci, or R-15ciR-19R-5ci or R-13

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 South Carolina uses

South Carolina enforces the 2009 IECC for homes (in effect since Jan 2013). 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

Two counties moved one zone warmer in the 2021 map: Beaufort County (3 → 2), Jasper County (3 → 2). If your town still enforces the 2018 or 2015 code, the older zone applies to permits.

Every county in South Carolina

NameZone (2021)Zone (2018)Details
Abbeville County3A3AInsulation →
Aiken County3A3AInsulation →
Allendale County3A3AInsulation →
Anderson County3A3AInsulation →
Bamberg County3A3AInsulation →
Barnwell County3A3AInsulation →
Beaufort County2A3A changedInsulation →
Berkeley County3A3AInsulation →
Calhoun County3A3AInsulation →
Charleston County3A3AInsulation →
Cherokee County3A3AInsulation →
Chester County3A3AInsulation →
Chesterfield County3A3AInsulation →
Clarendon County3A3AInsulation →
Colleton County3A3AInsulation →
Darlington County3A3AInsulation →
Dillon County3A3AInsulation →
Dorchester County3A3AInsulation →
Edgefield County3A3AInsulation →
Fairfield County3A3AInsulation →
Florence County3A3AInsulation →
Georgetown County3A3AInsulation →
Greenville County3A3AInsulation →
Greenwood County3A3AInsulation →
Hampton County3A3AInsulation →
Horry County3A3AInsulation →
Jasper County2A3A changedInsulation →
Kershaw County3A3AInsulation →
Lancaster County3A3AInsulation →
Laurens County3A3AInsulation →
Lee County3A3AInsulation →
Lexington County3A3AInsulation →
Marion County3A3AInsulation →
Marlboro County3A3AInsulation →
McCormick County3A3AInsulation →
Newberry County3A3AInsulation →
Oconee County3A3AInsulation →
Orangeburg County3A3AInsulation →
Pickens County3A3AInsulation →
Richland County3A3AInsulation →
Saluda County3A3AInsulation →
Spartanburg County3A3AInsulation →
Sumter County3A3AInsulation →
Union County3A3AInsulation →
Williamsburg County3A3AInsulation →
York County3A3AInsulation →

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 South Carolina?

South Carolina spans IECC climate zones 2A to 3A; 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 South Carolina?

The 2021 IECC calls for R-49 in the attic everywhere in South Carolina.

What energy code does South Carolina use?

South Carolina enforces the 2009 IECC for homes (in effect since Jan 2013). Source: US Department of Energy, September 2026. Local governments can adopt newer codes or amendments.

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