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Frost Line Depth by State: All 50 States and Who Sets It

Frost line depth by state runs from the 12 inch code minimum in mild climates to 60 inches in northern Minnesota, but in most states the number your footings must meet is set by your county, city or township, not the state. We found nine states that write it into their code: Michigan and Connecticut use 42 inches statewide, Massachusetts uses 48, Wisconsin uses at least 48, and the others vary by zone or county.

Quick answer

Under the IRC, every exterior footing goes at least 12 inches below undisturbed ground, and below the local frost line where the ground freezes. State codes set 42 in. in Michigan and Connecticut, 48 in. in Massachusetts and Wisconsin, 40 in. in most of Rhode Island and 42 to 60 in. in Minnesota. Everywhere else, your building department sets it.

12 in.IRC minimum footing depth

42 to 48 in.statewide in MI, CT, MA and WI

60 in.northern Minnesota, the deepest rule we found

How the building code sets the frost line

Most states build homes under some edition of the International Residential Code. In the 2021 IRC, Section R403.1.4 puts exterior footings at least 12 inches below undisturbed ground. Section R403.1.4.1 adds frost protection: footings go below the frost line, or use a frost-protected shallow foundation, an ASCE 32 design, or solid rock. Footings can’t bear on frozen soil unless it stays frozen.

The IRC itself doesn’t print a frost depth. Its Table R301.2 has a blank frost line column, and a footnote tells the local jurisdiction to fill in the minimum footing depth below finished grade.

So in code terms, the frost line is a policy number: how deep the bottom of a footing must sit. Some states fill it in for everyone; most leave it to each jurisdiction.

States that write a frost depth into their code

These nine states print footing depths in their residential code. Some use one number, others go zone by zone or county by county.

State	Footing depth in the state code
Connecticut	42 in. statewide
Indiana	24, 30 or 36 in., by county
Kentucky	24 in.; 27 to 33 in. in 19 eastern and northern counties
Massachusetts	48 in. statewide
Michigan	42 in. statewide
Minnesota	60 in. northern zone, 42 in. southern zone
New Jersey	30 in. south, 36 in. north
Rhode Island	40 in.; 30 in. in New Shoreham (Block Island)
Wisconsin	48 in. below adjacent grade (Uniform Dwelling Code, SPS 321.16)

Depths run from finished grade to the bottom of the footing. New Jersey’s south zone is Monmouth and Burlington counties and everything south of them. Minnesota allows a different depth where an engineer competent in soil mechanics determines one.

Examples of footing depths written into state codes, measured from finished grade to the bottom of the footing. Most states leave the number to local building departments.

Everywhere else, the local number governs

In the other states we found no statewide number, so the frost line comes from the city, county or township that enforces the code. We read the residential codes of the states linked below, and each leaves the frost line column for the local jurisdiction. North Carolina’s code prints a 12 inch minimum and says to check locally for frost depth. Florida’s lists the frost line as not applicable and keeps the 12 inch minimum footing depth.

To show how winters compare, this table groups those states by the IRC’s air-freezing index from Table R403.3(2), in degree days below 32°F. It combines how cold winter gets and how long it stays below freezing. It isn’t a frost depth, but it does set the footing depth for a frost-protected shallow foundation, covered below.

Coldest county’s air-freezing index	States where the local jurisdiction sets the frost line
1,500 or less in every county	Alabama, Arizona, Arkansas, Delaware, District of Columbia, Georgia, Hawaii, Kansas, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, West Virginia
Up to 2,000	California, Missouri, Nevada, Ohio, Pennsylvania, Washington
Up to 2,500	Illinois, Nebraska, New Mexico, New York
Up to 3,000	Iowa, Maine, Utah, Vermont
Up to 3,500	Idaho, South Dakota
Up to 4,000	Alaska, Colorado, Montana, New Hampshire, North Dakota, Wyoming

“Up to” means the coldest counties reach that band and milder counties sit lower. Linked states: we read the state code. Unlinked states: we found no statewide number, so ask your building department.

Frost line depth in all 50 states

Here’s the frost depth for every state: the statewide number where the state code sets one, and otherwise the depths that official city and county building departments publish, so you can see the range. Your own building department’s number is the one that counts.

Find your state:Jumps to your state’s full entry, with the official sources.

State	Who sets it	Statewide value or range	Local examples
Alabama	Local building department	Set locally	—
Alaska	Local building department	32-42 in. (32 in. in Juneau and Ketchikan; 42 in. in Fairbanks and Palmer)	City of Fairbanks: 42 in. (bottom of footing below finished grade unless engineered); City of Palmer: 42 in. below finished grade; City and Borough of Juneau: 32 in. minimum frost protection
Arizona	Local building department	0 in the low desert (Phoenix, Tucson) to 30 in. in Flagstaff	City of Phoenix: 0 (frost line entry in 2024 IRC amendments); City of Tucson: 0 (frost line entry in 2024 IRC amendments); City of Flagstaff: 30 in.
Arkansas	Local building department	12-18 in.	City of Little Rock: 12 in. (footings 12 in. deep minimum); City of Rogers: 18 in.; City of Mountain Home: 18 in.
California	Local building department	Set locally	Town of Truckee: 18 in. below 7,000 ft elevation; 24 in. above 7,000 ft; Town of Mammoth Lakes: 24 in.
Colorado	Local building department	30-36 in. on the Front Range (Greeley, Aurora); 40-48 in. in mountain towns (Blue River, Eagle)	City of Aurora: 36 in.; City of Greeley: 30 in.; Town of Eagle: 48 in.
Connecticut	State code	42 in. statewide	—
Delaware	Local building department	Set locally	Sussex County: 24 in. (to bottom of footing from final grade)
District of Columbia	Local building department	Set locally	District of Columbia (Dept. of Buildings deck guide): 30 in. below grade (deck footings)
Florida	State code	12 in. minimum footing depth below finished grade (FBC-Residential R403.1.4); no frost depth	—
Georgia	Local building department	5-18 in. in the jurisdictions listed; Alpharetta and Rome/Floyd County state a 12 in. minimum footing depth	City of Alpharetta: 5 in. frost line (12 in. minimum footing depth); Macon-Bibb County: 18 in.; Rome / Floyd County: 12 in. minimum
Hawaii	Local building department	Set locally	—
Idaho	Local building department	24-30 in.	City of Idaho Falls: 30 in. (finished grade to bottom of footing); City of Meridian: 24 in. minimum; City of Coeur d'Alene: 24 in. minimum
Illinois	Local building department	36-42 in.	City of Joliet: 42 in.; City of Peoria: 36 in.; City of Rock Island: 42 in.
Indiana	County table in state code	24, 30, or 36 in. minimum footing depth below finish grade, by county (e.g., 36 in. Lake, Allen, St. Joseph; 30 in. Marion, Hamilton; 24 in. Vanderburgh, Monroe)	—
Iowa	Local building department	42 in. in all three cities listed	City of Des Moines: 42 in.; City of Ames: 42 in.; City of West Des Moines: 42 in.
Kansas	Local building department	36 in. in all three cities listed	City of Olathe: 36 in.; City of Topeka: 36 in.; City of Salina: 36 in.
Kentucky	State code	24 in.; 27 to 33 in. in 19 eastern and northern counties	—
Louisiana	Local building department	Set locally	Village of Maurice (Vermilion Parish): 6 in. (2006 ordinance adopting the 2003 IRC)
Maine	Local building department	60 in. in both towns listed	City of Bangor: 60 in. (5 ft, listed under IBC base climate data); Town of Winslow: 60 in. (5 ft)
Maryland	Local building department	18 in. on the lower Eastern Shore (Wicomico) to 36 in. in western Maryland (Garrett); 30 in. in Montgomery County	Montgomery County: 30 in.; Wicomico County: 18 in.; Garrett County: 36 in. minimum (finish grade to bottom of footing)
Massachusetts	State code	48 in. statewide	—
Michigan	State code	42 in. statewide	—
Minnesota	County table in state code	60 in. Zone I (north); 42 in. Zone II (south)	—
Mississippi	Local building department	Set locally	City of Oxford: 12 in. minimum footing depth below grade (no frost depth stated)
Missouri	Local building department	24-36 in.	City of Independence: 36 in.; City of Columbia: 30 in.; City of Springfield: 24 in.
Montana	Local building department	36-48 in.; 42 in. in Billings and Helena	City of Billings: 42 in.; City of Helena: 42 in. minimum to bottom of footing; City of Bozeman: 36 in. one-story; 48 in. two-story
Nebraska	Local building department	36 in. in both cities listed	City of Lincoln: 36 in. (frost-free deck footings); City of Beatrice: 36 in.
Nevada	Local building department	12 in. in the Las Vegas valley; 24-30 in. in northern Nevada (Washoe County, Elko)	Clark County (Southern Nevada amendments): 12 in. (1 ft) up to 3,900 ft elevation; 36 in. (3 ft) above 3,900 ft; Washoe County: 24 in.; City of Elko: 30 in.
New Hampshire	Local building department	Set locally	Town of Durham: 48 in.
New Jersey	State code	30 in. (2 ft 6 in.) in southern NJ; 36 in. (3 ft) in northern NJ	—
New Mexico	Local building department	16-30 in. in the jurisdictions listed	City of Albuquerque: 16 in.; City of Farmington: 24 in.; San Juan County: 30 in. below grade
New York	Local building department	42-48 in. in the towns listed	Town of Ithaca (Tompkins County): 48 in.; Town of Ticonderoga: 48 in.; Town of Clarence (Erie County): 42 in. minimum
North Carolina	Local building department	12-18 in. in the counties listed (18 in. in Buncombe County)	Transylvania County: 12 in. minimum; Catawba County: 12 in.; Buncombe County (Asheville area): 18 in. frost line
North Dakota	Local building department	48-54 in.	City of Fargo: 54 in. (4.5 ft); City of Bismarck: 48 in. below finished grade; McKenzie County: 48 in.
Ohio	Local building department	32-42 in.	City of Columbus: 32 in.; City of Cleveland: 42 in. minimum footing depth below finish grade; Lucas County (Toledo area): 36 in. minimum footing depth below finish grade
Oklahoma	Local building department	Set locally	Oklahoma City: 18 in.
Oregon	Local building department	12-18 in. in the counties listed	Josephine County: 12 in. below 2,500 ft elevation; 18 in. above; Deschutes County: 18 in. minimum
Pennsylvania	Local building department	30-36 in. in the jurisdictions listed	Lower Providence Township (Montgomery County): 36 in.; City of Philadelphia: 30 in. (footings below grade); Centre Region COG (State College area): 36 in.
Rhode Island	State code	40 in.; 30 in. in New Shoreham (Block Island)	—
South Carolina	Local building department	0 in. on the coast (Charleston) to 12 in. upstate (York, Greenville counties)	York County: 12 in.; Greenville County: 12 in.; City of Charleston: 0 in.
South Dakota	Local building department	42-48 in.	City of Sioux Falls: 42 in.; City of Deadwood: 48 in.
Tennessee	Local building department	Set locally	Knox County: 12 in. minimum below undisturbed ground or finished grade (no frost depth stated)
Texas	Local building department	0-6 in. frost-line entries (Austin, Houston)	City of Houston: 6 in.; City of Austin: 0 (2007 ordinance adopting the 2006 IRC; confirm the current value with the city); City of Dallas: 12 in. minimum footing depth below undisturbed ground (amended R403.1.4)
Utah	Local building department	12 in. in St. George to 30 in. in Salt Lake County and the Uinta Basin	City of St. George: 12 in.; Duchesne County: 30 in.; City of Bluffdale (Salt Lake County): 30 in. (to bottom of footing)
Vermont	Local building department	Set locally	—
Virginia	Local building department	12 in. in Hampton Roads (Newport News) to 24 in. in Northern Virginia (Prince William)	Prince William County: 24 in.; City of Charlottesville: 18 in.; City of Newport News: 12 in.
Washington	Local building department	12 in. in Seattle to 24 in. in Spokane	City of Seattle: 12 in.; City and County of Spokane: 24 in. below finished grade (minimum)
West Virginia	Local building department	Set locally	—
Wisconsin	State code	48 in. below adjacent grade (Uniform Dwelling Code, SPS 321.16)	—
Wyoming	Local building department	Set locally	Town of Jackson: 34 in.

Statewide values from state codes; local examples from official building department pages and adopted code tables.

AlabamaCheck locally

Who sets it: Local building department
Good to know: Call your local building department for the frost depth that applies where you live.

AlaskaOfficial source

Who sets it: Local building department
Local examples: City of Fairbanks: 42 in. (bottom of footing below finished grade unless engineered) (source)
City of Palmer: 42 in. below finished grade (source)
City and Borough of Juneau: 32 in. minimum frost protection (source)
Typical range: 32-42 in. (32 in. in Juneau and Ketchikan; 42 in. in Fairbanks and Palmer)
Good to know: Ketchikan's adopted code (KMC 19.16, 2012 IRC) lists 32 in. below undisturbed soil where frost-susceptible materials are present. Anchorage isn't listed, so check with the city there.

Sources: fairbanks.gov · palmerak.org · juneau.org · codepublishing.com

ArizonaOfficial source

Who sets it: Local building department
Local examples: City of Phoenix: 0 (frost line entry in 2024 IRC amendments) (source)
City of Tucson: 0 (frost line entry in 2024 IRC amendments) (source)
City of Flagstaff: 30 in. (source)
Typical range: 0 in the low desert (Phoenix, Tucson) to 30 in. in Flagstaff
Good to know: In Phoenix and Tucson, a frost depth of 0 is not a footing depth, so confirm the minimum footing depth with the building department. Scottsdale requires footings at least 18 in. below undisturbed ground or engineered fill.

Sources: phoenix.gov · tucsonaz.gov · flagstaff.az.gov · ww2.scottsdaleaz.gov

ArkansasOfficial source

Who sets it: Local building department
Local examples: City of Little Rock: 12 in. (footings 12 in. deep minimum) (source)
City of Rogers: 18 in. (source)
City of Mountain Home: 18 in. (source)
Typical range: 12-18 in.
Good to know: Little Rock's design criteria sheet is dated Jan. 1, 2014, so confirm the current value with the city.

Sources: littlerock.gov · rogersar.gov · mountainhomear.gov

CaliforniaOfficial source

Who sets it: Local building department
Local examples: Town of Truckee: 18 in. below 7,000 ft elevation; 24 in. above 7,000 ft (source)
Town of Mammoth Lakes: 24 in. (source)
Good to know: The examples are Sierra mountain towns. For Los Angeles, San Francisco, Sacramento or San Diego, check with the local building department.

Sources: townoftruckee.gov · townofmammothlakes.ca.gov · docs.sandiego.gov

ColoradoOfficial source

Who sets it: Local building department
Local examples: City of Aurora: 36 in. (source)
City of Greeley: 30 in. (source)
Town of Eagle: 48 in. (source)
Typical range: 30-36 in. on the Front Range (Greeley, Aurora); 40-48 in. in mountain towns (Blue River, Eagle)
Good to know: Blue River's posted table lists 40 in. For Denver or the Pikes Peak Regional area, check with the building department directly.

Sources: auroraver2.hosted.civiclive.com · stg.greeleygov.com · townofeagle.org · townofblueriver.colorado.gov

ConnecticutSecondary source

Who sets it: State code
Statewide value: 42 in. statewide
Good to know: The 42 in. figure comes from State Building Inspector Interpretation I-12-05 (Oct. 2005), and New Haven's guidance also requires footings at least 42 in. below undisturbed ground. Confirm with your local building official under the current 2022 State Building Code.

Sources: portal.ct.gov · newhavenct.gov

DelawareOfficial source

Who sets it: Local building department
Local examples: Sussex County: 24 in. (to bottom of footing from final grade) (source)
Good to know: For New Castle or Kent County, check with the county building department.

Sources: sussexcountyde.gov

District of ColumbiaSecondary source

Who sets it: Local building department
Local examples: District of Columbia (Dept. of Buildings deck guide): 30 in. below grade (deck footings) (source)
Good to know: The 30 in. figure comes from the Department of Buildings deck guide (2017 DC Construction Codes), not a frost-line table. For house footings, confirm the depth with the Department of Buildings.

Sources: dob.dc.gov

FloridaSecondary source

Who sets it: State code
Statewide value: 12 in. minimum footing depth below finished grade (FBC-Residential R403.1.4); no frost depth
Good to know: The 12 in. figure is the Florida Building Code's general minimum footing depth (R403.1.4, 2017 6th Edition), not a frost depth. Confirm it with your building department under the current edition.

Sources: floridabuilding.org

GeorgiaOfficial source

Who sets it: Local building department
Local examples: City of Alpharetta: 5 in. frost line (12 in. minimum footing depth) (source)
Macon-Bibb County: 18 in. (source)
Rome / Floyd County: 12 in. minimum (source)
Typical range: 5-18 in. in the jurisdictions listed; Alpharetta and Rome/Floyd County state a 12 in. minimum footing depth
Good to know: Fayette County also lists a 5 in. frost line. Alpharetta's figures are for the 2024 IRC with Georgia amendments (revised 2026).

Sources: content.civicplus.com · maconbibb.us · floydcountyga.gov · fayettecountyga.gov

HawaiiCheck locally

Who sets it: Local building department
Good to know: Hawaii's 2018 State Residential Code amendments do not give a frost depth. Call your county building department for the required footing depth.

Sources: ags.hawaii.gov

IdahoOfficial source

Who sets it: Local building department
Local examples: City of Idaho Falls: 30 in. (finished grade to bottom of footing) (source)
City of Meridian: 24 in. minimum (source)
City of Coeur d'Alene: 24 in. minimum (source)
Typical range: 24-30 in.

Sources: idahofallsidaho.gov · dir.meridiancity.org · cdaid.org

IllinoisOfficial source

Who sets it: Local building department
Local examples: City of Joliet: 42 in. (source)
City of Peoria: 36 in. (source)
City of Rock Island: 42 in. (source)
Typical range: 36-42 in.
Good to know: Chicago Municipal Code 13-132-100 requires footings 42 in. (3 ft 6 in.) below grade, but that is older Title 13 text, so confirm it under the current Chicago Construction Codes.

Sources: joliet.gov · peoriagov.org · rigov.org · dev-codelibrary.amlegal.com

IndianaOfficial source

Who sets it: County table in state code
Statewide value: 24, 30, or 36 in. minimum footing depth below finish grade, by county (e.g., 36 in. Lake, Allen, St. Joseph; 30 in. Marion, Hamilton; 24 in. Vanderburgh, Monroe)
Good to know: Indiana's code (675 IAC 14-4.4-5) assigns all 92 counties a depth: 27 northern counties at 36 in., 29 central counties at 30 in. and 36 southern counties at 24 in. The depth is measured from finished grade to the bottom of the footing.

Sources: regulations.justia.com · regulations.justia.com

IowaOfficial source

Who sets it: Local building department
Local examples: City of Des Moines: 42 in. (source)
City of Ames: 42 in. (source)
City of West Des Moines: 42 in. (source)
Typical range: 42 in. in all three cities listed
Good to know: Des Moines sets its 42 in. frost line in Ordinance 16,224, Sec. 26-300(f) (Feb. 2023).

Sources: councildocs.dsm.city · cityofames.org · wdm.iowa.gov

KansasOfficial source

Who sets it: Local building department
Local examples: City of Olathe: 36 in. (source)
City of Topeka: 36 in. (source)
City of Salina: 36 in. (source)
Typical range: 36 in. in all three cities listed

Sources: codepublishing.com · topeka.municipal.codes · salina-ks.gov

KentuckyOfficial source

Who sets it: State code
Statewide value: 24 in.; 27 to 33 in. in 19 eastern and northern counties
Good to know: Under the 2018 Kentucky Residential Code (Table R403.1.4), the depth is 27 in. in Bell, Clay, Knox, Lawrence and Owsley; 30 in. in Boone, Breathitt, Campbell, Harlan, Johnson, Kenton, Leslie, Magoffin and Perry; 33 in. in Floyd, Knott, Letcher, Martin and Pike; and 24 in. in all other counties.

Sources: dhbc.ky.gov · apps.legislature.ky.gov

LouisianaSecondary source

Who sets it: Local building department
Local examples: Village of Maurice (Vermilion Parish): 6 in. (2006 ordinance adopting the 2003 IRC) (source)
Good to know: The Maurice figure comes from a 2006 ordinance that adopted the 2003 IRC. Check with your parish or city building department for the current depth.

Sources: townofmaurice.gov · brla.gov · nola.gov

MaineOfficial source

Who sets it: Local building department
Local examples: City of Bangor: 60 in. (5 ft, listed under IBC base climate data) (source)
Town of Winslow: 60 in. (5 ft) (source)
Typical range: 60 in. in both towns listed

Sources: bangormaine.gov · winslow-me.gov

MarylandOfficial source

Who sets it: Local building department
Local examples: Montgomery County: 30 in. (source)
Wicomico County: 18 in. (source)
Garrett County: 36 in. minimum (finish grade to bottom of footing) (source)
Typical range: 18 in. on the lower Eastern Shore (Wicomico) to 36 in. in western Maryland (Garrett); 30 in. in Montgomery County
Good to know: Queen Anne's County lists 24 in., and Baltimore City's amendment to IBC 1809.5 uses 30 in. below grade. County tables are posted on the Maryland Department of Labor website.

Sources: montgomerycountymd.gov · dllr.state.md.us · garrettcountymd.gov · dllr.state.md.us · codes.baltimorecity.gov

MassachusettsOfficial source

Who sets it: State code
Statewide value: 48 in. statewide
Good to know: The 48 in. frost line is in the Massachusetts Residential Code (780 CMR 51, Table R301.2(1)). Frost-protected shallow foundations are covered separately under R403.3.

Sources: regulations.justia.com

MichiganOfficial source

Who sets it: State code
Statewide value: 42 in. statewide
Good to know: The 42 in. frost line is set in Mich. Admin. Code R 408.30516 (Table R301.2(1)), effective Aug. 29, 2025.

Sources: law.cornell.edu

MinnesotaOfficial source

Who sets it: County table in state code
Statewide value: 60 in. Zone I (north); 42 in. Zone II (south)
Good to know: Minn. R. 1303.1600 puts each county in a zone, for example St. Louis, Clay and Beltrami in Zone I and Hennepin, Ramsey and Olmsted in Zone II. An engineer competent in soil mechanics can justify a shallower depth.

Sources: revisor.mn.gov

MississippiOfficial source

Who sets it: Local building department
Local examples: City of Oxford: 12 in. minimum footing depth below grade (no frost depth stated) (source)
Good to know: Mississippi's factory-built home rule (19 Miss. Code R. 7-5.06.7.5) requires pier footings below the frost line but gives no number. Check with your local building department for the required depth.

Sources: oxfordms.net · law.cornell.edu

MissouriOfficial source

Who sets it: Local building department
Local examples: City of Independence: 36 in. (source)
City of Columbia: 30 in. (source)
City of Springfield: 24 in. (source)
Typical range: 24-36 in.
Good to know: Springfield's 24 in. figure comes from its residential accessory structure permit application.

Sources: independencemo.gov · como.gov · springfieldmo.gov

MontanaOfficial source

Who sets it: Local building department
Local examples: City of Billings: 42 in. (source)
City of Helena: 42 in. minimum to bottom of footing (source)
City of Bozeman: 36 in. one-story; 48 in. two-story (source)
Typical range: 36-48 in.; 42 in. in Billings and Helena
Good to know: Bozeman sets footing depth by building height rather than a single frost line.

Sources: billingsmt.gov · helenamt.gov · bozemanmt.gov

NebraskaOfficial source

Who sets it: Local building department
Local examples: City of Lincoln: 36 in. (frost-free deck footings) (source)
City of Beatrice: 36 in. (source)
Typical range: 36 in. in both cities listed

Sources: lincoln.ne.gov · beatrice.ne.gov

NevadaOfficial source

Who sets it: Local building department
Local examples: Clark County (Southern Nevada amendments): 12 in. (1 ft) up to 3,900 ft elevation; 36 in. (3 ft) above 3,900 ft (source)
Washoe County: 24 in. (source)
City of Elko: 30 in. (source)
Typical range: 12 in. in the Las Vegas valley; 24-30 in. in northern Nevada (Washoe County, Elko)
Good to know: Clark County labels its 36 in. figure for areas above 3,900 ft for use under the International Building Code (IBC).

Sources: clarkcountynv.gov · washoecounty.gov · elkocity.com

New HampshireOfficial source

Who sets it: Local building department
Local examples: Town of Durham: 48 in. (source)
Good to know: Durham's 48 in. comes from its 2021 IRC table. Other towns set their own, so check with your town building department.

Sources: ci.durham.nh.us

New JerseyOfficial source

Who sets it: State code
Statewide value: 30 in. (2 ft 6 in.) in southern NJ; 36 in. (3 ft) in northern NJ
Good to know: Under N.J.A.C. 5:23-3.21, southern NJ is Monmouth and Burlington counties and all counties to the south; northern NJ is Mercer and Middlesex counties and all counties to the north.

Sources: regulations.justia.com

New MexicoOfficial source

Who sets it: Local building department
Local examples: City of Albuquerque: 16 in. (source)
City of Farmington: 24 in. (source)
San Juan County: 30 in. below grade (source)
Typical range: 16-30 in. in the jurisdictions listed
Good to know: State code (14.7.3.12.B NMAC) requires exterior footings at least 12 in. below grade; the frost depth itself comes from local tables. Albuquerque's figure is from a 2017 handout.

Sources: documents.cabq.gov · farmingtonnm.gov · sjcounty.net · rld.nm.gov

New YorkOfficial source

Who sets it: Local building department
Local examples: Town of Ithaca (Tompkins County): 48 in. (source)
Town of Ticonderoga: 48 in. (source)
Town of Clarence (Erie County): 42 in. minimum (source)
Typical range: 42-48 in. in the towns listed
Good to know: The Town of Ithaca figure is for the 2025 Residential Code of New York State. For New York City, Buffalo or Albany, check with the local building department.

Sources: townithacany.gov · townofticonderoga.gov · www4.erie.gov

North CarolinaSecondary source

Who sets it: Local building department
Local examples: Transylvania County: 12 in. minimum (source)
Catawba County: 12 in. (source)
Buncombe County (Asheville area): 18 in. frost line (source)
Typical range: 12-18 in. in the counties listed (18 in. in Buncombe County)
Good to know: The North Carolina Residential Code (R403.1.4, 2009 NC amendments) requires exterior footings to extend below the frost line and never less than 12 in. below undisturbed ground. Depths vary by county, such as 18 in. in Buncombe County, so check with yours.

Sources: transylvaniacounty.org · catawbacountync.gov · ncosfm.gov

North DakotaOfficial source

Who sets it: Local building department
Local examples: City of Fargo: 54 in. (4.5 ft) (source)
City of Bismarck: 48 in. below finished grade (source)
McKenzie County: 48 in. (source)
Typical range: 48-54 in.
Good to know: Fargo does not require footings for attached uncovered decks to reach its 54 in. (4.5 ft) frost depth.

Sources: download.fargond.gov · download.fargond.gov · bismarcknd.gov · mckenziecountynd.gov

OhioOfficial source

Who sets it: Local building department
Local examples: City of Columbus: 32 in. (source)
City of Cleveland: 42 in. minimum footing depth below finish grade (source)
Lucas County (Toledo area): 36 in. minimum footing depth below finish grade (source)
Typical range: 32-42 in.
Good to know: Mansfield's posted table also shows 36 in. Columbus's figure is from a sheet revised in April 2026.

Sources: columbus.gov · clevelandohio.gov · co.lucas.oh.us · mansfieldohio.gov

OklahomaOfficial source

Who sets it: Local building department
Local examples: Oklahoma City: 18 in. (source)
Good to know: Oklahoma's statewide residential code rule (OAC 748:20-6-8) leaves frost depth to the local authority. Tulsa's residential guide gives no depth, so Tulsa residents should ask the city.

Sources: okc.gov · regulations.justia.com

OregonSecondary source

Who sets it: Local building department
Local examples: Josephine County: 12 in. below 2,500 ft elevation; 18 in. above (source)
Deschutes County: 18 in. minimum (source)
Typical range: 12-18 in. in the counties listed
Good to know: Oregon's Building Codes Division gives a site-specific frost line depth for residential projects through its online Design Criteria Hub.

Sources: oregon.gov · cms9files.revize.com · deschutescounty.gov

PennsylvaniaOfficial source

Who sets it: Local building department
Local examples: Lower Providence Township (Montgomery County): 36 in. (source)
City of Philadelphia: 30 in. (footings below grade) (source)
Centre Region COG (State College area): 36 in. (source)
Typical range: 30-36 in. in the jurisdictions listed
Good to know: Pennsylvania's Uniform Construction Code leaves the frost depth to each municipality or its code agency, so the local building department's number is the one that counts.

Sources: lowerprovidence.org · phila.gov · crcog.net

Rhode IslandOfficial source

Who sets it: State code
Statewide value: 40 in.; 30 in. in New Shoreham (Block Island)
Good to know: Both figures are set in the state code at 510-RICR-00-00-2.5 (Table R301.2(1) and Note 2).

Sources: regulations.justia.com

South CarolinaOfficial source

Who sets it: Local building department
Local examples: York County: 12 in. (source)
Greenville County: 12 in. (source)
City of Charleston: 0 in. (source)
Typical range: 0 in. on the coast (Charleston) to 12 in. upstate (York, Greenville counties)
Good to know: Greenville County's figure comes from its 2019 code adoption ordinance. Charleston's table is for the 2021 South Carolina Building Codes.

Sources: yorkcountygov.com · greenvillecounty.org · charleston-sc.gov

South DakotaOfficial source

Who sets it: Local building department
Local examples: City of Sioux Falls: 42 in. (source)
City of Deadwood: 48 in. (source)
Typical range: 42-48 in.

Sources: siouxfalls.gov · cityofdeadwood.com

TennesseeOfficial source

Who sets it: Local building department
Local examples: Knox County: 12 in. minimum below undisturbed ground or finished grade (no frost depth stated) (source)
Good to know: Knox County gives a minimum footing depth, not a frost depth. For Memphis, Shelby County or Nashville, check with the local codes department.

Sources: KnoxCounty.org

TexasOfficial source

Who sets it: Local building department
Local examples: City of Houston: 6 in. (source)
City of Austin: 0 (2007 ordinance adopting the 2006 IRC; confirm the current value with the city) (source)
City of Dallas: 12 in. minimum footing depth below undisturbed ground (amended R403.1.4) (source)
Typical range: 0-6 in. frost-line entries (Austin, Houston)
Good to know: Austin's 0 comes from a 2007 ordinance (20071018-089) under the 2006 IRC, and the city now uses a newer code, so confirm with the city. Panhandle cities such as Amarillo and Lubbock aren't listed, so check with them directly.

Sources: houstontx.gov · services.austintexas.gov · dallascityhall.com

UtahOfficial source

Who sets it: Local building department
Local examples: City of St. George: 12 in. (source)
Duchesne County: 30 in. (source)
City of Bluffdale (Salt Lake County): 30 in. (to bottom of footing) (source)
Typical range: 12 in. in St. George to 30 in. in Salt Lake County and the Uinta Basin
Good to know: Utah's statewide residential code amendments (Utah Code 15A-3-202) don't change frost depth, so it is set locally. Herriman's posted table also shows 30 in.

Sources: stgeorge.municipal.codes · duchesne.utah.gov · bluffdale.gov · herriman.gov · le.utah.gov

VermontCheck locally

Who sets it: Local building department
Good to know: Call your local building official for the frost depth that applies where you live.

VirginiaOfficial source

Who sets it: Local building department
Local examples: Prince William County: 24 in. (source)
City of Charlottesville: 18 in. (source)
City of Newport News: 12 in. (source)
Typical range: 12 in. in Hampton Roads (Newport News) to 24 in. in Northern Virginia (Prince William)
Good to know: Virginia's western mountain counties aren't listed, so check with your county building department.

Sources: pwcva.gov · charlottesville.gov · nnva.gov

WashingtonOfficial source

Who sets it: Local building department
Local examples: City of Seattle: 12 in. (source)
City and County of Spokane: 24 in. below finished grade (minimum) (source)
Typical range: 12 in. in Seattle to 24 in. in Spokane
Good to know: Mason County also lists 12 in.

Sources: seattle.gov · static.spokanecity.org · masoncountywa.gov

West VirginiaCheck locally

Who sets it: Local building department
Good to know: Call your local building department for the frost depth that applies where you live.

WisconsinSecondary source

Who sets it: State code
Statewide value: 48 in. below adjacent grade (Uniform Dwelling Code, SPS 321.16)
Good to know: Wisconsin's Uniform Dwelling Code applies statewide to one- and two-family homes and requires footings and foundations at least 48 in. below adjacent grade. Ask your building inspector about exceptions such as frost-protected shallow foundations.

Sources: foxcrossingwi.gov · twinlakeswi.gov

WyomingOfficial source

Who sets it: Local building department
Local examples: Town of Jackson: 34 in. (source)
Good to know: For Cheyenne, Casper or other towns, check with the local building department.

Sources: jacksonwy.gov

Last checked October 31, 2026 against official state and local sources for all 51 entries. Rules change; your state agency or local building department has the final word. Spot something out of date? Email info@muthlerlandscaping.com and we’ll fix it.

Frost line depth in Pennsylvania

Pennsylvania’s Uniform Construction Code has used the 2021 IRC for houses since January 1, 2026, according to the City of York’s summary. That leaves the frost depth to the municipality or its code agency. Lower Providence Township in Montgomery County, for example, publishes design criteria with a 36 inch frost line depth. Other townships set their own.

In the IRC’s freezing-index table, most Pennsylvania counties sit in the mildest band, 1,500 or less, while 26 counties, including Centre, Clinton, Lycoming, Potter and Tioga, are rated 2,000. We build in Pennsylvania, and we confirm the frost depth with the township or its code agency before we dig a footing.

How to find the frost depth for your address

There’s no official frost depth by zip code. Online lookups estimate from maps, while the number an inspector checks is the one your jurisdiction adopted. To get it:

Call the city, county or township building department and ask what depth it requires for footings.
Look for a posted design criteria table. Many departments publish one, the way Camp Verde, Arizona lists 12 inches.

Measure from finished grade. If fill or a patio will go against the house later, the footing depth counts from where the final ground will be.

What has to go below the frost line

Footings for houses, additions, attached garages and any other structure the code doesn’t exempt need frost protection. Under the 2021 IRC, small freestanding accessory buildings are exempt: 600 square feet or less in light-frame construction, or 400 square feet or less in other construction, with eaves no higher than 10 feet.

Decks follow the IRC’s deck section. In the 2021 IRC, every deck footing goes at least 12 inches below undisturbed ground (R507.3.2), and it needs frost protection when the deck is attached to a frost-protected structure such as the house (R507.3.3). Our guide to freestanding deck plans covers how those are framed. Local codes can differ, so ask.

Patios and walks aren’t foundations. A paver patio sits on compacted base, which is why fixing pavers heaving in winter starts with base and drainage, not depth. A pergola on a patio is different: its posts need real footings, covered in our guide to anchoring a pergola to pavers.

Frost-protected shallow foundations

A frost-protected shallow foundation wraps the footing in rigid foam so the ground under it stays above freezing. The IRC allows it under R403.3 for buildings kept at a monthly mean of 64°F or warmer, with insulation labeled to ASTM C578. It can’t be used for unheated spaces like garages, porches and carports.

Minimum footing depth is 12 inches where the air-freezing index is 1,500 or less, 14 inches at 2,000 and 16 inches from 2,500 to 4,000, with more insulation as the index rises. It’s a designed detail, so plan it with your designer and inspector.

Builder’s note: Check footing depth from finished grade with a laser or string line, not from the spoil pile beside the hole. A footing a few inches shy of the required depth can fail inspection, and digging a little deeper is a lot easier than pouring twice.

Mini excavator doing site prep on a residential job — A Wacker Neuson EZ36 mini excavator doing site prep on one of our jobs.

When to call a pro

Footings for an addition, garage or attached deck, which need a permit and inspection
Clay, wet ground or a high water table, where frost heave risk is higher and drainage matters as much as depth
Rock or ledge above the frost line
Frost-protected shallow foundations, which are designed, not guessed

Call 811 before any digging so utilities get marked. Our foundation digging guide covers excavation and site prep for slabs, garage pads and pole barns. If you’d like a deck or pergola laid out on paper before anyone digs, our online deck design service draws it.

Frequently Asked Questions

How deep is the frost line?

In code terms, it’s the footing depth your jurisdiction requires: from the 12 inch IRC minimum in mild climates to 60 inches in northern Minnesota.

What is the frost line depth in Pennsylvania?

Each municipality sets it under the state’s Uniform Construction Code. Lower Providence Township lists 36 inches; call your township or its code agency for yours.

Is there a frost line depth map?

The IRC doesn’t publish a frost depth map. It has an air-freezing index map and county table for frost-protected shallow foundations; the footing depth that governs is your local one.

Can I find frost depth by zip code?

Not officially. Zip code tools estimate, but the number an inspector checks is the one your building department adopted.

Do deck footings have to go below the frost line?

Under the 2021 IRC, yes when the deck is attached to the house or another frost-protected structure, and every deck footing goes at least 12 inches deep. A freestanding deck may be exempt, but local codes vary, so ask your building department before you dig.

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In central PA? We pour and build flatwork. See our concrete work.

More state guides: 811 dig laws · Retaining wall permits · Contractor licensing · Contractor deposit limits · Building codes · Planting zones · Mechanics lien deadlines · Workers’ comp · Frost dates · Drainage laws · All state guides · Free calculators

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Cite as: Muthler Landscaping & Construction, “Frost Line Depth by State: All 50 States and Who Sets It,” https://muthlerlandscaping.com/state-guides/frost-line-depth/ (last checked November 1, 2026).

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