Climate Zone 2
Climate zone 2 is the IECC's "hot" zone. Under the 2021 map it covers 259 counties in 9 states, including Houston, Dallas and Phoenix. By moisture: 2A (humid) 239 and 2B (dry) 20. Zone 2 is hot for most of the year. Attic insulation and low solar-gain windows do most of the work; walls need only R-13.
Insulation minimums in zone 2 (2021 IECC)
| Part of the house | 2A, 2B |
|---|---|
| Attic / ceiling | R-49 |
| Wood-frame walls | R-13, or R-10ci |
| Mass walls (block, brick) | R-4 exterior / R-6 interior |
| Floors over unheated space | R-13 |
| Basement walls | None required |
| Slab edge | None required |
| Crawl space walls | None required |
| Windows: max U-factor | U-0.40 |
| Windows: max SHGC | 0.25 |
"13+5ci" means R-13 between the studs plus R-5 foam board over the outside. Minimums from 2021 IECC Table R402.1.3; many areas still enforce an older edition, so check with your building department.
Existing home? ENERGY STAR recommends R-49 in an uninsulated attic, or adding R-38 if you already have 3–4 inches. The climate zone lookup works out how many inches to add for your county.
States in climate zone 2
| State | Counties in zone 2 | Subzones |
|---|---|---|
| Texas | 95 of 254 | 2A, 2B |
| Florida | 63 of 67 | 2A |
| Georgia | 41 of 159 | 2A |
| Louisiana | 37 of 64 | 2A |
| Alabama | 9 of 67 | 2A |
| Mississippi | 6 of 82 | 2A |
| Arizona | 5 of 15 | 2B |
| South Carolina | 2 of 46 | 2A |
| California | 1 of 58 | 2B |
Every county in zone 2
Open a state to see its counties. The state pages list every county's zone, including the ones in other zones.
Texas (95)
- Anderson County (2A)
- Angelina County (2A)
- Aransas County (2A)
- Atascosa County (2A)
- Austin County (2A)
- Bandera County (2B)
- Bastrop County (2A)
- Bee County (2A)
- Bell County (2A)
- Bexar County (2A)
- Bosque County (2A)
- Brazoria County (2A)
- Brazos County (2A)
- Brooks County (2A)
- Burleson County (2A)
- Caldwell County (2A)
- Calhoun County (2A)
- Chambers County (2A)
- Cherokee County (2A)
- Colorado County (2A)
- Comal County (2A)
- Coryell County (2A)
- Dallas County (2A)
- DeWitt County (2A)
- Dimmit County (2B)
- Duval County (2A)
- Edwards County (2B)
- Ellis County (2A)
- Falls County (2A)
- Fayette County (2A)
- Fort Bend County (2A)
- Freestone County (2A)
- Frio County (2B)
- Galveston County (2A)
- Goliad County (2A)
- Gonzales County (2A)
- Grimes County (2A)
- Guadalupe County (2A)
- Hardin County (2A)
- Harris County (2A)
- Hays County (2A)
- Hill County (2A)
- Houston County (2A)
- Jackson County (2A)
- Jasper County (2A)
- Jefferson County (2A)
- Jim Hogg County (2A)
- Jim Wells County (2A)
- Johnson County (2A)
- Karnes County (2A)
- Kenedy County (2A)
- Kinney County (2B)
- Kleberg County (2A)
- La Salle County (2B)
- Lavaca County (2A)
- Lee County (2A)
- Leon County (2A)
- Liberty County (2A)
- Limestone County (2A)
- Live Oak County (2A)
- Madison County (2A)
- Matagorda County (2A)
- Maverick County (2B)
- McLennan County (2A)
- McMullen County (2A)
- Medina County (2B)
- Milam County (2A)
- Montgomery County (2A)
- Navarro County (2A)
- Newton County (2A)
- Nueces County (2A)
- Orange County (2A)
- Polk County (2A)
- Real County (2B)
- Refugio County (2A)
- Robertson County (2A)
- San Jacinto County (2A)
- San Patricio County (2A)
- Starr County (2A)
- Tarrant County (2A)
- Travis County (2A)
- Trinity County (2A)
- Tyler County (2A)
- Uvalde County (2B)
- Val Verde County (2B)
- Victoria County (2A)
- Walker County (2A)
- Waller County (2A)
- Washington County (2A)
- Webb County (2B)
- Wharton County (2A)
- Williamson County (2A)
- Wilson County (2A)
- Zapata County (2B)
- Zavala County (2B)
Florida (63)
- Alachua County (2A)
- Baker County (2A)
- Bay County (2A)
- Bradford County (2A)
- Brevard County (2A)
- Calhoun County (2A)
- Charlotte County (2A)
- Citrus County (2A)
- Clay County (2A)
- Collier County (2A)
- Columbia County (2A)
- DeSoto County (2A)
- Dixie County (2A)
- Duval County (2A)
- Escambia County (2A)
- Flagler County (2A)
- Franklin County (2A)
- Gadsden County (2A)
- Gilchrist County (2A)
- Glades County (2A)
- Gulf County (2A)
- Hamilton County (2A)
- Hardee County (2A)
- Hendry County (2A)
- Hernando County (2A)
- Highlands County (2A)
- Hillsborough County (2A)
- Holmes County (2A)
- Indian River County (2A)
- Jackson County (2A)
- Jefferson County (2A)
- Lafayette County (2A)
- Lake County (2A)
- Lee County (2A)
- Leon County (2A)
- Levy County (2A)
- Liberty County (2A)
- Madison County (2A)
- Manatee County (2A)
- Marion County (2A)
- Martin County (2A)
- Nassau County (2A)
- Okaloosa County (2A)
- Okeechobee County (2A)
- Orange County (2A)
- Osceola County (2A)
- Pasco County (2A)
- Pinellas County (2A)
- Polk County (2A)
- Putnam County (2A)
- Santa Rosa County (2A)
- Sarasota County (2A)
- Seminole County (2A)
- St. Johns County (2A)
- St. Lucie County (2A)
- Sumter County (2A)
- Suwannee County (2A)
- Taylor County (2A)
- Union County (2A)
- Volusia County (2A)
- Wakulla County (2A)
- Walton County (2A)
- Washington County (2A)
Georgia (41)
- Appling County (2A)
- Atkinson County (2A)
- Bacon County (2A)
- Baker County (2A)
- Berrien County (2A)
- Brantley County (2A)
- Brooks County (2A)
- Bryan County (2A)
- Calhoun County (2A)
- Camden County (2A)
- Charlton County (2A)
- Chatham County (2A)
- Clinch County (2A)
- Coffee County (2A)
- Colquitt County (2A)
- Cook County (2A)
- Decatur County (2A)
- Dougherty County (2A)
- Early County (2A)
- Echols County (2A)
- Effingham County (2A)
- Evans County (2A)
- Glynn County (2A)
- Grady County (2A)
- Jeff Davis County (2A)
- Lanier County (2A)
- Liberty County (2A)
- Long County (2A)
- Lowndes County (2A)
- McIntosh County (2A)
- Miller County (2A)
- Mitchell County (2A)
- Pierce County (2A)
- Seminole County (2A)
- Tattnall County (2A)
- Thomas County (2A)
- Tift County (2A)
- Toombs County (2A)
- Ware County (2A)
- Wayne County (2A)
- Worth County (2A)
Louisiana (37)
- Acadia Parish (2A)
- Allen Parish (2A)
- Ascension Parish (2A)
- Assumption Parish (2A)
- Avoyelles Parish (2A)
- Beauregard Parish (2A)
- Calcasieu Parish (2A)
- Cameron Parish (2A)
- East Baton Rouge Parish (2A)
- East Feliciana Parish (2A)
- Evangeline Parish (2A)
- Iberia Parish (2A)
- Iberville Parish (2A)
- Jefferson Parish (2A)
- Jefferson Davis Parish (2A)
- Lafayette Parish (2A)
- Lafourche Parish (2A)
- Livingston Parish (2A)
- Orleans Parish (2A)
- Plaquemines Parish (2A)
- Pointe Coupee Parish (2A)
- Rapides Parish (2A)
- St. Bernard Parish (2A)
- St. Charles Parish (2A)
- St. Helena Parish (2A)
- St. James Parish (2A)
- St. John the Baptist Parish (2A)
- St. Landry Parish (2A)
- St. Martin Parish (2A)
- St. Mary Parish (2A)
- St. Tammany Parish (2A)
- Tangipahoa Parish (2A)
- Terrebonne Parish (2A)
- Vermilion Parish (2A)
- Washington Parish (2A)
- West Baton Rouge Parish (2A)
- West Feliciana Parish (2A)
Alabama (9)
- Baldwin County (2A)
- Coffee County (2A)
- Covington County (2A)
- Dale County (2A)
- Escambia County (2A)
- Geneva County (2A)
- Henry County (2A)
- Houston County (2A)
- Mobile County (2A)
Mississippi (6)
- George County (2A)
- Hancock County (2A)
- Harrison County (2A)
- Jackson County (2A)
- Pearl River County (2A)
- Stone County (2A)
Arizona (5)
- La Paz County (2B)
- Maricopa County (2B)
- Pima County (2B)
- Pinal County (2B)
- Yuma County (2B)
South Carolina (2)
- Beaufort County (2A)
- Jasper County (2A)
California (1)
- Imperial County (2B)
What changed in the 2021 map
21 of these counties moved here from zone 3 in the 2021 map. The 2021 code redrew the map with newer weather data; across the US, most counties that changed moved one zone warmer. If your town still enforces the 2018 or an older code, the old zone applies to permits.
Frequently asked questions
What is climate zone 2?
One of the eight US climate zones in the International Energy Conservation Code (IECC). Zone 2 is hot for most of the year. Attic insulation and low solar-gain windows do most of the work; walls need only R-13. It covers 259 counties in 9 states.
How much attic insulation do I need in climate zone 2?
In zone 2, the 2021 IECC calls for R-49 in the attic of a new home. For an existing home, ENERGY STAR recommends R-49 in an uninsulated attic, or adding R-38 if you already have 3–4 inches.
Which states are in climate zone 2?
Texas, Florida, Georgia, Louisiana, Alabama, Mississippi, Arizona, South Carolina and California.
What do the letters A and B mean?
They describe moisture: 2A is humid and 2B is dry. In zone 2 the insulation minimums in the table above are the same for every letter.
Sources: Pacific Northwest National Laboratory, Guide to Determining Climate Zone by County (2022); 2021 IECC Table R402.1.3; ENERGY STAR. See how we calculate.