Frost Line Depth
Frost Depth & Snow Load
How deep footings must go below finished grade to sit under the frost line, as adopted locally in IRC Table R301.2 or an amendment to R403.1.4.
How Frost Line Depth Rules Differ by Place
Aurora, CO: Aurora Frost Depth: 36 Inches for Foundations
Some RestrictionsAurora requires a minimum frost depth of 36 inches for foundations, published by the city's Building Division in its Engineering Design Criteria for the 2021 I-Codes.
Denver, CO: Denver Frost Line Depth: 36 Inches Below Grade
Some RestrictionsDenver sets its frost line at 36 inches below finished grade, stated both in the residential design criteria table and as a flat declaration in the commercial code.
Greeley, CO: Greeley Frost Line Depth: 30 Inches
Some RestrictionsGreeley sets its frost line depth at 30 inches in the design criteria table added to its municipal code: six inches shallower than Denver and Aurora.
Lakewood, CO: Lakewood CO Frost Depth: 36 Inches
Some RestrictionsLakewood sets a frost depth of 36 inches in the Codes and Loads handout its Public Works permit office publishes, matching neighbouring Denver.
Cincinnati, OH: Cincinnati OH Footing Depth: 30 Inches Below Grade
Some RestrictionsCincinnati requires footings a minimum of 30 inches below grade: the shallowest figure of any Ohio city we cover, and the city never labels it a frost line depth.
Cleveland, OH: Cleveland Footing Depth: 3 Feet for Houses, 3 Feet 6 Inches Otherwise
Some RestrictionsCleveland sets footing depth in its own codified building code, and gives houses a shallower figure than everything else: 3 feet for one and two family dwellings, 3 feet 6 inches for…
Frost Line Depth Rules by State
Statewide law governs this topic in many states. Each entry links to that state's full page.
Connecticut
Significant RestrictionsConnecticut sets a single frost line depth of 42 inches for the whole state, written into the state building code rather than left to each town to decide.
Indiana
Some RestrictionsIndiana sets footing depth county by county in a single state table: 24 inches across much of the south, 30 inches through the middle of the state, and 36 inches along the northern…
Massachusetts
Significant RestrictionsMassachusetts sets one frost line depth for the whole state: 48 inches. Footings must bear below that depth anywhere in the Commonwealth, and cities and towns do not set their own…
New Jersey
Significant RestrictionsNew Jersey splits the state into two frost zones: 2 feet 6 inches in Monmouth and Burlington counties and everything south, and 3 feet in Mercer and Middlesex counties and everything…
Ohio
Some RestrictionsOhio does not set a statewide frost line depth. The Residential Code of Ohio leaves that column blank and directs each jurisdiction to fill in its own minimum footing depth.
Rhode Island
Significant RestrictionsRhode Island sets frost depth at 3 feet 4 inches, 40 inches, in 38 of its 39 municipalities, with New Shoreham on Block Island the single exception at 2 feet 6 inches.
Vermont
Significant RestrictionsVermont's statewide code requires foundations to extend below the frost line and not less than 5 feet below finished grade, but by statute it does not reach owner-occupied…
Wisconsin
Significant RestrictionsWisconsin requires footings and foundations to sit below the frost penetration level or at least 48 inches below adjacent grade, whichever is deeper, so 48 inches is a floor, not a…
Cities & Counties with Frost Line Depth Rules
12 locations
Colorado
Other Frost Depth & Snow Load Topics
Ground Snow Load
The ground snow load in pounds per square foot (Pg) the jurisdiction adopted, which sets what roofs and structures must be designed to carry.
Roof Snow Load
The minimum roof or flat-roof design snow load (Pf), a different quantity from ground snow load, where the jurisdiction adopts its own figure.
Deck Footing Depth
How deep deck and porch footings must be set, plus the size, attachment and permit thresholds that apply to decks specifically.
Fence Post Depth
How deep fence posts must be set relative to the local frost line, and when a fence needs a permit or an inspected footing.
Frost-Protected Shallow Foundations
Whether the jurisdiction permits a frost-protected shallow foundation under IRC R403.3 instead of digging to the full frost depth, and on what terms.
Building Design Criteria
The full set of local design criteria, wind speed, seismic design category, weathering, termite risk and ice-barrier requirements, as adopted.