Climate zones
Climate Zone 5
Climate zone 5 is the IECC's "cool" zone. Under the 2021 map it covers 789 counties in 33 states, including Chicago, Denver, Boston and Salt Lake City. By moisture: 5A (humid) 636, 5B (dry) 146 and 5C (marine) 7. Zone 5 is heating-dominated. Expect R-60 in the attic, R-30 floors over unheated spaces and insulated basement walls.
Insulation minimums in zone 5 (2021 IECC)
| Part of the house | 5A, 5B, 5C |
|---|---|
| Attic / ceiling | R-60 |
| Wood-frame walls | R-30, or 20+5ci, or 13+10ci, or R-20ci |
| Mass walls (block, brick) | R-13 exterior / R-17 interior |
| Floors over unheated space | R-30 |
| Basement walls | R-15ci, or R-19, or 13+5ci |
| Slab edge | R-10, 4 ft deep |
| Crawl space walls | R-15ci, or R-19, or 13+5ci |
| Windows: max U-factor | U-0.30 |
| Windows: max SHGC | 0.40 |
"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-60 in an uninsulated attic, or adding R-49 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 5
| State | Counties in zone 5 | Subzones |
|---|---|---|
| Nebraska | all 93 | 5A |
| Iowa | 84 of 99 | 5A |
| Ohio | 64 of 88 | 5A |
| Illinois | 58 of 102 | 5A |
| Pennsylvania | 53 of 67 | 5A |
| Indiana | 47 of 92 | 5A |
| Michigan | 37 of 83 | 5A |
| New York | 36 of 62 | 5A |
| Colorado | 34 of 64 | 5B |
| Wisconsin | 30 of 72 | 5A |
| Missouri | 26 of 115 | 5A |
| Idaho | 22 of 44 | 5B |
| Washington | 22 of 39 | 5B, 5C |
| Utah | 21 of 29 | 5B |
| West Virginia | 19 of 55 | 5A |
| Oregon | 18 of 36 | 5B |
| South Dakota | 18 of 66 | 5A |
| Kansas | 17 of 105 | 5A |
| Massachusetts | all 14 | 5A |
| New Mexico | 12 of 33 | 5B |
| Nevada | 9 of 17 | 5B |
| Connecticut | all 8 | 5A |
| New Jersey | 7 of 21 | 5A |
| California | 6 of 58 | 5B |
| New Hampshire | 5 of 10 | 5A |
| North Carolina | 5 of 100 | 5A |
| Rhode Island | all 5 | 5A |
| Virginia | 5 of 136 | 5A |
| Alaska | 3 of 27 | 5C |
| Arizona | 3 of 15 | 5B |
| Minnesota | 3 of 87 | 5A |
| Wyoming | 3 of 23 | 5B |
| Maryland | 2 of 24 | 5A |
Every county in zone 5
Open a state to see its counties. The state pages list every county's zone, including the ones in other zones.
Nebraska (93)
- Adams County (5A)
- Antelope County (5A)
- Arthur County (5A)
- Banner County (5A)
- Blaine County (5A)
- Boone County (5A)
- Box Butte County (5A)
- Boyd County (5A)
- Brown County (5A)
- Buffalo County (5A)
- Burt County (5A)
- Butler County (5A)
- Cass County (5A)
- Cedar County (5A)
- Chase County (5A)
- Cherry County (5A)
- Cheyenne County (5A)
- Clay County (5A)
- Colfax County (5A)
- Cuming County (5A)
- Custer County (5A)
- Dakota County (5A)
- Dawes County (5A)
- Dawson County (5A)
- Deuel County (5A)
- Dixon County (5A)
- Dodge County (5A)
- Douglas County (5A)
- Dundy County (5A)
- Fillmore County (5A)
- Franklin County (5A)
- Frontier County (5A)
- Furnas County (5A)
- Gage County (5A)
- Garden County (5A)
- Garfield County (5A)
- Gosper County (5A)
- Grant County (5A)
- Greeley County (5A)
- Hall County (5A)
- Hamilton County (5A)
- Harlan County (5A)
- Hayes County (5A)
- Hitchcock County (5A)
- Holt County (5A)
- Hooker County (5A)
- Howard County (5A)
- Jefferson County (5A)
- Johnson County (5A)
- Kearney County (5A)
- Keith County (5A)
- Keya Paha County (5A)
- Kimball County (5A)
- Knox County (5A)
- Lancaster County (5A)
- Lincoln County (5A)
- Logan County (5A)
- Loup County (5A)
- Madison County (5A)
- McPherson County (5A)
- Merrick County (5A)
- Morrill County (5A)
- Nance County (5A)
- Nemaha County (5A)
- Nuckolls County (5A)
- Otoe County (5A)
- Pawnee County (5A)
- Perkins County (5A)
- Phelps County (5A)
- Pierce County (5A)
- Platte County (5A)
- Polk County (5A)
- Red Willow County (5A)
- Richardson County (5A)
- Rock County (5A)
- Saline County (5A)
- Sarpy County (5A)
- Saunders County (5A)
- Scotts Bluff County (5A)
- Seward County (5A)
- Sheridan County (5A)
- Sherman County (5A)
- Sioux County (5A)
- Stanton County (5A)
- Thayer County (5A)
- Thomas County (5A)
- Thurston County (5A)
- Valley County (5A)
- Washington County (5A)
- Wayne County (5A)
- Webster County (5A)
- Wheeler County (5A)
- York County (5A)
Iowa (84)
- Adair County (5A)
- Adams County (5A)
- Allamakee County (5A)
- Appanoose County (5A)
- Audubon County (5A)
- Benton County (5A)
- Boone County (5A)
- Bremer County (5A)
- Buchanan County (5A)
- Buena Vista County (5A)
- Butler County (5A)
- Calhoun County (5A)
- Carroll County (5A)
- Cass County (5A)
- Cedar County (5A)
- Cherokee County (5A)
- Chickasaw County (5A)
- Clarke County (5A)
- Clayton County (5A)
- Clinton County (5A)
- Crawford County (5A)
- Dallas County (5A)
- Davis County (5A)
- Decatur County (5A)
- Delaware County (5A)
- Des Moines County (5A)
- Dubuque County (5A)
- Fayette County (5A)
- Floyd County (5A)
- Franklin County (5A)
- Fremont County (5A)
- Greene County (5A)
- Grundy County (5A)
- Guthrie County (5A)
- Hamilton County (5A)
- Hardin County (5A)
- Harrison County (5A)
- Henry County (5A)
- Howard County (5A)
- Humboldt County (5A)
- Ida County (5A)
- Iowa County (5A)
- Jackson County (5A)
- Jasper County (5A)
- Jefferson County (5A)
- Johnson County (5A)
- Jones County (5A)
- Keokuk County (5A)
- Lee County (5A)
- Linn County (5A)
- Louisa County (5A)
- Lucas County (5A)
- Madison County (5A)
- Mahaska County (5A)
- Marion County (5A)
- Marshall County (5A)
- Mills County (5A)
- Monona County (5A)
- Monroe County (5A)
- Montgomery County (5A)
- Muscatine County (5A)
- Page County (5A)
- Plymouth County (5A)
- Pocahontas County (5A)
- Polk County (5A)
- Pottawattamie County (5A)
- Poweshiek County (5A)
- Ringgold County (5A)
- Sac County (5A)
- Scott County (5A)
- Shelby County (5A)
- Story County (5A)
- Tama County (5A)
- Taylor County (5A)
- Union County (5A)
- Van Buren County (5A)
- Wapello County (5A)
- Warren County (5A)
- Washington County (5A)
- Wayne County (5A)
- Webster County (5A)
- Winneshiek County (5A)
- Woodbury County (5A)
- Wright County (5A)
Ohio (64)
- Allen County (5A)
- Ashland County (5A)
- Ashtabula County (5A)
- Auglaize County (5A)
- Belmont County (5A)
- Carroll County (5A)
- Champaign County (5A)
- Clark County (5A)
- Columbiana County (5A)
- Coshocton County (5A)
- Crawford County (5A)
- Cuyahoga County (5A)
- Darke County (5A)
- Defiance County (5A)
- Delaware County (5A)
- Erie County (5A)
- Fairfield County (5A)
- Fulton County (5A)
- Geauga County (5A)
- Guernsey County (5A)
- Hancock County (5A)
- Hardin County (5A)
- Harrison County (5A)
- Henry County (5A)
- Holmes County (5A)
- Huron County (5A)
- Jefferson County (5A)
- Knox County (5A)
- Lake County (5A)
- Licking County (5A)
- Logan County (5A)
- Lorain County (5A)
- Lucas County (5A)
- Mahoning County (5A)
- Marion County (5A)
- Medina County (5A)
- Mercer County (5A)
- Miami County (5A)
- Monroe County (5A)
- Montgomery County (5A)
- Morgan County (5A)
- Morrow County (5A)
- Muskingum County (5A)
- Noble County (5A)
- Ottawa County (5A)
- Paulding County (5A)
- Perry County (5A)
- Portage County (5A)
- Preble County (5A)
- Putnam County (5A)
- Richland County (5A)
- Sandusky County (5A)
- Seneca County (5A)
- Shelby County (5A)
- Stark County (5A)
- Summit County (5A)
- Trumbull County (5A)
- Tuscarawas County (5A)
- Union County (5A)
- Van Wert County (5A)
- Wayne County (5A)
- Williams County (5A)
- Wood County (5A)
- Wyandot County (5A)
Illinois (58)
- Adams County (5A)
- Boone County (5A)
- Brown County (5A)
- Bureau County (5A)
- Carroll County (5A)
- Cass County (5A)
- Champaign County (5A)
- Cook County (5A)
- De Witt County (5A)
- DeKalb County (5A)
- Douglas County (5A)
- DuPage County (5A)
- Edgar County (5A)
- Ford County (5A)
- Fulton County (5A)
- Grundy County (5A)
- Hancock County (5A)
- Henderson County (5A)
- Henry County (5A)
- Iroquois County (5A)
- Jo Daviess County (5A)
- Kane County (5A)
- Kankakee County (5A)
- Kendall County (5A)
- Knox County (5A)
- La Salle County (5A)
- Lake County (5A)
- Lee County (5A)
- Livingston County (5A)
- Logan County (5A)
- Macon County (5A)
- Marshall County (5A)
- Mason County (5A)
- McDonough County (5A)
- McHenry County (5A)
- McLean County (5A)
- Menard County (5A)
- Mercer County (5A)
- Morgan County (5A)
- Moultrie County (5A)
- Ogle County (5A)
- Peoria County (5A)
- Piatt County (5A)
- Pike County (5A)
- Putnam County (5A)
- Rock Island County (5A)
- Sangamon County (5A)
- Schuyler County (5A)
- Scott County (5A)
- Stark County (5A)
- Stephenson County (5A)
- Tazewell County (5A)
- Vermilion County (5A)
- Warren County (5A)
- Whiteside County (5A)
- Will County (5A)
- Winnebago County (5A)
- Woodford County (5A)
Pennsylvania (53)
- Allegheny County (5A)
- Armstrong County (5A)
- Beaver County (5A)
- Bedford County (5A)
- Blair County (5A)
- Bradford County (5A)
- Butler County (5A)
- Cambria County (5A)
- Cameron County (5A)
- Carbon County (5A)
- Centre County (5A)
- Clarion County (5A)
- Clearfield County (5A)
- Clinton County (5A)
- Columbia County (5A)
- Crawford County (5A)
- Elk County (5A)
- Erie County (5A)
- Fayette County (5A)
- Forest County (5A)
- Fulton County (5A)
- Greene County (5A)
- Huntingdon County (5A)
- Indiana County (5A)
- Jefferson County (5A)
- Juniata County (5A)
- Lackawanna County (5A)
- Lawrence County (5A)
- Lehigh County (5A)
- Luzerne County (5A)
- Lycoming County (5A)
- McKean County (5A)
- Mercer County (5A)
- Mifflin County (5A)
- Monroe County (5A)
- Montour County (5A)
- Northampton County (5A)
- Northumberland County (5A)
- Pike County (5A)
- Potter County (5A)
- Schuylkill County (5A)
- Snyder County (5A)
- Somerset County (5A)
- Sullivan County (5A)
- Susquehanna County (5A)
- Tioga County (5A)
- Union County (5A)
- Venango County (5A)
- Warren County (5A)
- Washington County (5A)
- Wayne County (5A)
- Westmoreland County (5A)
- Wyoming County (5A)
Indiana (47)
- Adams County (5A)
- Allen County (5A)
- Benton County (5A)
- Blackford County (5A)
- Boone County (5A)
- Carroll County (5A)
- Cass County (5A)
- Clinton County (5A)
- De Kalb County (5A)
- Delaware County (5A)
- Elkhart County (5A)
- Fountain County (5A)
- Fulton County (5A)
- Grant County (5A)
- Hamilton County (5A)
- Hancock County (5A)
- Henry County (5A)
- Howard County (5A)
- Huntington County (5A)
- Jasper County (5A)
- Jay County (5A)
- Kosciusko County (5A)
- La Porte County (5A)
- Lagrange County (5A)
- Lake County (5A)
- Madison County (5A)
- Marshall County (5A)
- Miami County (5A)
- Montgomery County (5A)
- Newton County (5A)
- Noble County (5A)
- Parke County (5A)
- Porter County (5A)
- Pulaski County (5A)
- Randolph County (5A)
- St. Joseph County (5A)
- Starke County (5A)
- Steuben County (5A)
- Tippecanoe County (5A)
- Tipton County (5A)
- Vermillion County (5A)
- Wabash County (5A)
- Warren County (5A)
- Wayne County (5A)
- Wells County (5A)
- White County (5A)
- Whitley County (5A)
Michigan (37)
- Allegan County (5A)
- Barry County (5A)
- Bay County (5A)
- Berrien County (5A)
- Branch County (5A)
- Calhoun County (5A)
- Cass County (5A)
- Clinton County (5A)
- Eaton County (5A)
- Genesee County (5A)
- Gratiot County (5A)
- Hillsdale County (5A)
- Huron County (5A)
- Ingham County (5A)
- Ionia County (5A)
- Jackson County (5A)
- Kalamazoo County (5A)
- Kent County (5A)
- Lapeer County (5A)
- Lenawee County (5A)
- Livingston County (5A)
- Macomb County (5A)
- Midland County (5A)
- Monroe County (5A)
- Montcalm County (5A)
- Muskegon County (5A)
- Oakland County (5A)
- Ottawa County (5A)
- Saginaw County (5A)
- Sanilac County (5A)
- Shiawassee County (5A)
- St. Clair County (5A)
- St. Joseph County (5A)
- Tuscola County (5A)
- Van Buren County (5A)
- Washtenaw County (5A)
- Wayne County (5A)
New York (36)
- Albany County (5A)
- Allegany County (5A)
- Broome County (5A)
- Cattaraugus County (5A)
- Cayuga County (5A)
- Chautauqua County (5A)
- Chemung County (5A)
- Columbia County (5A)
- Cortland County (5A)
- Dutchess County (5A)
- Erie County (5A)
- Genesee County (5A)
- Greene County (5A)
- Livingston County (5A)
- Monroe County (5A)
- Niagara County (5A)
- Onondaga County (5A)
- Ontario County (5A)
- Orange County (5A)
- Orleans County (5A)
- Oswego County (5A)
- Putnam County (5A)
- Rensselaer County (5A)
- Rockland County (5A)
- Saratoga County (5A)
- Schenectady County (5A)
- Schoharie County (5A)
- Schuyler County (5A)
- Seneca County (5A)
- Steuben County (5A)
- Tioga County (5A)
- Tompkins County (5A)
- Washington County (5A)
- Wayne County (5A)
- Wyoming County (5A)
- Yates County (5A)
Colorado (34)
- Adams County (5B)
- Arapahoe County (5B)
- Boulder County (5B)
- Broomfield County (5B)
- Cheyenne County (5B)
- Crowley County (5B)
- Custer County (5B)
- Delta County (5B)
- Denver County (5B)
- Douglas County (5B)
- El Paso County (5B)
- Elbert County (5B)
- Fremont County (5B)
- Garfield County (5B)
- Gilpin County (5B)
- Huerfano County (5B)
- Jefferson County (5B)
- Kiowa County (5B)
- Kit Carson County (5B)
- La Plata County (5B)
- Larimer County (5B)
- Lincoln County (5B)
- Logan County (5B)
- Mesa County (5B)
- Montezuma County (5B)
- Montrose County (5B)
- Morgan County (5B)
- Phillips County (5B)
- Pueblo County (5B)
- Sedgwick County (5B)
- Teller County (5B)
- Washington County (5B)
- Weld County (5B)
- Yuma County (5B)
Wisconsin (30)
- Adams County (5A)
- Calumet County (5A)
- Columbia County (5A)
- Crawford County (5A)
- Dane County (5A)
- Dodge County (5A)
- Fond du Lac County (5A)
- Grant County (5A)
- Green County (5A)
- Green Lake County (5A)
- Iowa County (5A)
- Jefferson County (5A)
- Juneau County (5A)
- Kenosha County (5A)
- La Crosse County (5A)
- Lafayette County (5A)
- Milwaukee County (5A)
- Monroe County (5A)
- Outagamie County (5A)
- Ozaukee County (5A)
- Racine County (5A)
- Richland County (5A)
- Rock County (5A)
- Sauk County (5A)
- Vernon County (5A)
- Walworth County (5A)
- Washington County (5A)
- Waukesha County (5A)
- Waushara County (5A)
- Winnebago County (5A)
Missouri (26)
- Adair County (5A)
- Andrew County (5A)
- Atchison County (5A)
- Clark County (5A)
- Daviess County (5A)
- DeKalb County (5A)
- Gentry County (5A)
- Grundy County (5A)
- Harrison County (5A)
- Holt County (5A)
- Knox County (5A)
- Lewis County (5A)
- Linn County (5A)
- Livingston County (5A)
- Macon County (5A)
- Marion County (5A)
- Mercer County (5A)
- Nodaway County (5A)
- Pike County (5A)
- Putnam County (5A)
- Ralls County (5A)
- Schuyler County (5A)
- Scotland County (5A)
- Shelby County (5A)
- Sullivan County (5A)
- Worth County (5A)
Idaho (22)
- Ada County (5B)
- Benewah County (5B)
- Canyon County (5B)
- Cassia County (5B)
- Clearwater County (5B)
- Elmore County (5B)
- Gem County (5B)
- Gooding County (5B)
- Idaho County (5B)
- Jerome County (5B)
- Kootenai County (5B)
- Latah County (5B)
- Lewis County (5B)
- Lincoln County (5B)
- Minidoka County (5B)
- Nez Perce County (5B)
- Owyhee County (5B)
- Payette County (5B)
- Power County (5B)
- Shoshone County (5B)
- Twin Falls County (5B)
- Washington County (5B)
Washington (22)
- Adams County (5B)
- Asotin County (5B)
- Benton County (5B)
- Chelan County (5B)
- Clallam County (5C)
- Columbia County (5B)
- Douglas County (5B)
- Franklin County (5B)
- Garfield County (5B)
- Grant County (5B)
- Island County (5C)
- Kitsap County (5C)
- Kittitas County (5B)
- Klickitat County (5B)
- Lincoln County (5B)
- Okanogan County (5B)
- San Juan County (5C)
- Skamania County (5B)
- Spokane County (5B)
- Walla Walla County (5B)
- Whitman County (5B)
- Yakima County (5B)
Utah (21)
- Beaver County (5B)
- Box Elder County (5B)
- Cache County (5B)
- Carbon County (5B)
- Davis County (5B)
- Emery County (5B)
- Garfield County (5B)
- Grand County (5B)
- Iron County (5B)
- Juab County (5B)
- Kane County (5B)
- Millard County (5B)
- Piute County (5B)
- Salt Lake County (5B)
- San Juan County (5B)
- Sanpete County (5B)
- Sevier County (5B)
- Tooele County (5B)
- Utah County (5B)
- Wayne County (5B)
- Weber County (5B)
West Virginia (19)
- Barbour County (5A)
- Brooke County (5A)
- Grant County (5A)
- Hampshire County (5A)
- Hancock County (5A)
- Hardy County (5A)
- Harrison County (5A)
- Marion County (5A)
- Marshall County (5A)
- Mineral County (5A)
- Monongalia County (5A)
- Ohio County (5A)
- Pendleton County (5A)
- Pocahontas County (5A)
- Preston County (5A)
- Randolph County (5A)
- Taylor County (5A)
- Tucker County (5A)
- Wetzel County (5A)
Oregon (18)
- Baker County (5B)
- Crook County (5B)
- Deschutes County (5B)
- Gilliam County (5B)
- Grant County (5B)
- Harney County (5B)
- Hood River County (5B)
- Jefferson County (5B)
- Klamath County (5B)
- Lake County (5B)
- Malheur County (5B)
- Morrow County (5B)
- Sherman County (5B)
- Umatilla County (5B)
- Union County (5B)
- Wallowa County (5B)
- Wasco County (5B)
- Wheeler County (5B)
South Dakota (18)
- Bennett County (5A)
- Bon Homme County (5A)
- Brule County (5A)
- Charles Mix County (5A)
- Clay County (5A)
- Douglas County (5A)
- Gregory County (5A)
- Haakon County (5A)
- Hutchinson County (5A)
- Jackson County (5A)
- Jones County (5A)
- Lyman County (5A)
- Mellette County (5A)
- Stanley County (5A)
- Todd County (5A)
- Tripp County (5A)
- Union County (5A)
- Yankton County (5A)
Kansas (17)
- Cheyenne County (5A)
- Decatur County (5A)
- Gove County (5A)
- Greeley County (5A)
- Jewell County (5A)
- Logan County (5A)
- Norton County (5A)
- Phillips County (5A)
- Rawlins County (5A)
- Republic County (5A)
- Scott County (5A)
- Sheridan County (5A)
- Sherman County (5A)
- Smith County (5A)
- Thomas County (5A)
- Wallace County (5A)
- Wichita County (5A)
Massachusetts (14)
- Barnstable County (5A)
- Berkshire County (5A)
- Bristol County (5A)
- Dukes County (5A)
- Essex County (5A)
- Franklin County (5A)
- Hampden County (5A)
- Hampshire County (5A)
- Middlesex County (5A)
- Nantucket County (5A)
- Norfolk County (5A)
- Plymouth County (5A)
- Suffolk County (5A)
- Worcester County (5A)
New Mexico (12)
- Colfax County (5B)
- Harding County (5B)
- Los Alamos County (5B)
- McKinley County (5B)
- Mora County (5B)
- Rio Arriba County (5B)
- San Juan County (5B)
- San Miguel County (5B)
- Sandoval County (5B)
- Santa Fe County (5B)
- Taos County (5B)
- Torrance County (5B)
Nevada (9)
- Churchill County (5B)
- Elko County (5B)
- Eureka County (5B)
- Humboldt County (5B)
- Lander County (5B)
- Pershing County (5B)
- Storey County (5B)
- Washoe County (5B)
- White Pine County (5B)
Connecticut (8)
- Fairfield County (5A)
- Hartford County (5A)
- Litchfield County (5A)
- Middlesex County (5A)
- New Haven County (5A)
- New London County (5A)
- Tolland County (5A)
- Windham County (5A)
New Jersey (7)
- Bergen County (5A)
- Hunterdon County (5A)
- Morris County (5A)
- Passaic County (5A)
- Somerset County (5A)
- Sussex County (5A)
- Warren County (5A)
California (6)
- Lassen County (5B)
- Modoc County (5B)
- Nevada County (5B)
- Plumas County (5B)
- Sierra County (5B)
- Siskiyou County (5B)
New Hampshire (5)
- Cheshire County (5A)
- Hillsborough County (5A)
- Merrimack County (5A)
- Rockingham County (5A)
- Strafford County (5A)
North Carolina (5)
- Alleghany County (5A)
- Ashe County (5A)
- Avery County (5A)
- Watauga County (5A)
- Yancey County (5A)
Rhode Island (5)
- Bristol County (5A)
- Kent County (5A)
- Newport County (5A)
- Providence County (5A)
- Washington County (5A)
Virginia (5)
- Alleghany County (5A)
- Bath County (5A)
- Clifton Forge (independent city) (5A)
- Covington (independent city) (5A)
- Highland County (5A)
Alaska (3)
- Ketchikan Gateway (5C)
- Prince of Wales-Outer Ketchikan Census Area (5C)
- Sitka (5C)
Arizona (3)
- Apache County (5B)
- Coconino County (5B)
- Navajo County (5B)
Minnesota (3)
- Fillmore County (5A)
- Houston County (5A)
- Winona County (5A)
Wyoming (3)
- Goshen County (5B)
- Laramie County (5B)
- Platte County (5B)
Maryland (2)
- Allegany County (5A)
- Garrett County (5A)
What changed in the 2021 map
101 of these counties were in a different zone under the 2018 map: 91 moved here from a colder zone and 10 from a warmer one. 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 5?
One of the eight US climate zones in the International Energy Conservation Code (IECC). Zone 5 is heating-dominated. Expect R-60 in the attic, R-30 floors over unheated spaces and insulated basement walls. It covers 789 counties in 33 states.
How much attic insulation do I need in climate zone 5?
In zone 5, the 2021 IECC calls for R-60 in the attic of a new home. For an existing home, ENERGY STAR recommends R-60 in an uninsulated attic, or adding R-49 if you already have 3–4 inches.
Which states are in climate zone 5?
Nebraska, Iowa, Ohio, Illinois, Pennsylvania, Indiana, Michigan, New York, Colorado, Wisconsin, Missouri, Idaho, Washington, Utah, West Virginia, Oregon, South Dakota, Kansas, Massachusetts, New Mexico, Nevada, Connecticut, New Jersey, California, New Hampshire, North Carolina, Rhode Island, Virginia, Alaska, Arizona, Minnesota, Wyoming and Maryland. Nebraska, Massachusetts, Connecticut and Rhode Island are entirely in zone 5.
What do the letters A, B and C mean?
They describe moisture: 5A is humid, 5B is dry and 5C is marine (the mild, damp Pacific coast). In zone 5 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.