Climate zones by state

Kentucky Climate Zones by County

All 120 of Kentucky's counties are in climate zone 4A under the 2021 International Energy Conservation Code (IECC).

Insulation minimums in Kentucky (zone 4A)

ZoneAtticWood-frame wallsFloors over unheated spaceBasement walls
4AR-60R-30, or 20+5ci, or 13+10ci, or R-20ciR-19R-10ci 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 Kentucky uses

Kentucky enforces the 2009 IECC for homes (in effect since Oct 2014). 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

None of Kentucky's counties changed zone between the 2018 and 2021 maps.

Every county in Kentucky

NameZone (2021)Zone (2018)Details
Adair County4A4AInsulation →
Allen County4A4AInsulation →
Anderson County4A4AInsulation →
Ballard County4A4AInsulation →
Barren County4A4AInsulation →
Bath County4A4AInsulation →
Bell County4A4AInsulation →
Boone County4A4AInsulation →
Bourbon County4A4AInsulation →
Boyd County4A4AInsulation →
Boyle County4A4AInsulation →
Bracken County4A4AInsulation →
Breathitt County4A4AInsulation →
Breckinridge County4A4AInsulation →
Bullitt County4A4AInsulation →
Butler County4A4AInsulation →
Caldwell County4A4AInsulation →
Calloway County4A4AInsulation →
Campbell County4A4AInsulation →
Carlisle County4A4AInsulation →
Carroll County4A4AInsulation →
Carter County4A4AInsulation →
Casey County4A4AInsulation →
Christian County4A4AInsulation →
Clark County4A4AInsulation →
Clay County4A4AInsulation →
Clinton County4A4AInsulation →
Crittenden County4A4AInsulation →
Cumberland County4A4AInsulation →
Daviess County4A4AInsulation →
Edmonson County4A4AInsulation →
Elliott County4A4AInsulation →
Estill County4A4AInsulation →
Fayette County4A4AInsulation →
Fleming County4A4AInsulation →
Floyd County4A4AInsulation →
Franklin County4A4AInsulation →
Fulton County4A4AInsulation →
Gallatin County4A4AInsulation →
Garrard County4A4AInsulation →
Grant County4A4AInsulation →
Graves County4A4AInsulation →
Grayson County4A4AInsulation →
Green County4A4AInsulation →
Greenup County4A4AInsulation →
Hancock County4A4AInsulation →
Hardin County4A4AInsulation →
Harlan County4A4AInsulation →
Harrison County4A4AInsulation →
Hart County4A4AInsulation →
Henderson County4A4AInsulation →
Henry County4A4AInsulation →
Hickman County4A4AInsulation →
Hopkins County4A4AInsulation →
Jackson County4A4AInsulation →
Jefferson County4A4AInsulation →
Jessamine County4A4AInsulation →
Johnson County4A4AInsulation →
Kenton County4A4AInsulation →
Knott County4A4AInsulation →
Knox County4A4AInsulation →
Larue County4A4AInsulation →
Laurel County4A4AInsulation →
Lawrence County4A4AInsulation →
Lee County4A4AInsulation →
Leslie County4A4AInsulation →
Letcher County4A4AInsulation →
Lewis County4A4AInsulation →
Lincoln County4A4AInsulation →
Livingston County4A4AInsulation →
Logan County4A4AInsulation →
Lyon County4A4AInsulation →
Madison County4A4AInsulation →
Magoffin County4A4AInsulation →
Marion County4A4AInsulation →
Marshall County4A4AInsulation →
Martin County4A4AInsulation →
Mason County4A4AInsulation →
McCracken County4A4AInsulation →
McCreary County4A4AInsulation →
McLean County4A4AInsulation →
Meade County4A4AInsulation →
Menifee County4A4AInsulation →
Mercer County4A4AInsulation →
Metcalfe County4A4AInsulation →
Monroe County4A4AInsulation →
Montgomery County4A4AInsulation →
Morgan County4A4AInsulation →
Muhlenberg County4A4AInsulation →
Nelson County4A4AInsulation →
Nicholas County4A4AInsulation →
Ohio County4A4AInsulation →
Oldham County4A4AInsulation →
Owen County4A4AInsulation →
Owsley County4A4AInsulation →
Pendleton County4A4AInsulation →
Perry County4A4AInsulation →
Pike County4A4AInsulation →
Powell County4A4AInsulation →
Pulaski County4A4AInsulation →
Robertson County4A4AInsulation →
Rockcastle County4A4AInsulation →
Rowan County4A4AInsulation →
Russell County4A4AInsulation →
Scott County4A4AInsulation →
Shelby County4A4AInsulation →
Simpson County4A4AInsulation →
Spencer County4A4AInsulation →
Taylor County4A4AInsulation →
Todd County4A4AInsulation →
Trigg County4A4AInsulation →
Trimble County4A4AInsulation →
Union County4A4AInsulation →
Warren County4A4AInsulation →
Washington County4A4AInsulation →
Wayne County4A4AInsulation →
Webster County4A4AInsulation →
Whitley County4A4AInsulation →
Wolfe County4A4AInsulation →
Woodford 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 Kentucky?

Kentucky is IECC climate zone 4A under the 2021 code.

How much attic insulation do I need in Kentucky?

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

What energy code does Kentucky use?

Kentucky enforces the 2009 IECC for homes (in effect since Oct 2014). Source: US Department of Energy, September 2026. Local governments can adopt newer codes or amendments.

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