Frost Heave and Foundations in Cold Climates

Last reviewed October 28, 2026 · 3 sources cited

Frost heave needs three things at the same time: soil that holds water in a way that favors ice growth, water to feed it, and freezing temperatures. Remove any one and it does not occur, which is why drainage and insulation are the main tools.

How frost heave works

Fine Homebuilding explains that water in frost-susceptible soil gathers into ice lenses at the frost line, drawing more water up by capillary action. As lenses grow, they lift the soil and any structure above. When they thaw, soil fills the voids, so the foundation settles and the cycle repeats. Heave requires frost-susceptible soil, moisture and freezing temperatures; removing any one prevents it.^[1]

Frost depth and building code options

The International Residential Code (section R403.1.4.1, as described by Fine Homebuilding) offers four options for protecting footings: excavate below the frost depth, use a frost-protected shallow foundation, design to the ASCE 32 standard, or bear on solid rock.^[1] Frost depth depends on local climate, so building departments publish a design frost depth for each area.

Frost-protected shallow foundations

A frost-protected shallow foundation (FPSF) uses insulation around the perimeter, and sometimes horizontal insulation extending outward, to keep the ground under a heated building from freezing. HUD's 1994 research report, prepared by the NAHB Research Center, found FPSFs can be as shallow as 16 inches in the most severe U.S. climates, noted that heating a building raises the frost line near the foundation, and reported no subgrade freezing in test homes in Vermont, Iowa, North Dakota and Alaska.^[2] Fine Homebuilding adds that footing depth can be as little as 12 inches in warm areas, that heated buildings must be maintained above 64°F year-round, and that FPSF requires gravel under the footing that drains to daylight except in free-draining soils.^[1]

Signs on an existing house

• Porches, steps, decks and unheated additions that rise, tilt or crack in winter and settle back in spring. InterNACHI notes frost heaving, often under porches, can cause piers to rise or tilt.^[3]
• Horizontal cracks in basement walls in cold regions. Frost-heaved soil is one possible cause.^[3] See bowed basement walls.
• Doors that stick in winter and free up in warm weather, in combination with other signs.

What reduces frost problems

• Drainage. Keep the ground around the foundation from staying wet; see water and drainage.
• Heat and insulation. Unheated spaces such as a vacant house, a garage or an enclosed porch are the most exposed. HUD's research notes heating a building raises the frost line near its foundation.^[2]
• Removing the water source. Downspout discharge near a footing can supply the water.
• Engineer's advice. Retrofits such as insulation or drainage near footings are site-specific.

Note that HUD's report is from 1994 and addresses new construction design. It informs how frost behaves but is not a repair manual.