Frost Line Depth in Farmington Hills, MI: 42 in (Michigan rule)

State-set value

42in

107 cm · 3 ft 6 in

42 in (Michigan rule)

Set by the state: Michigan Residential Code R403.1.4 (R 408.30522); the building official may modify.

Source and how we checked

Farmington Hills does not publish its own value; the state rule applies.

Document: codes.iccsafe.org

Climate: 146 nights a year at or below 32 °F (NOAA 1991–2020, Farmington, 1.5 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

146nights a year at or below 32 °F
49%of nearby soil rated “high” for frost action (USDA)

How deep is the frost line in Farmington Hills?

Michigan sets the frost footing depth for Farmington Hills at 42 in (107 cm). Footings, piers and other permanent supports must reach at least this depth (IRC R403.1.4.1).

Who sets the frost line depth in Farmington Hills?

Michigan writes this depth into its statewide residential code, so Farmington Hills’s building department enforces the state’s number rather than setting its own. Oakland County uses the same 42 in, so the depth does not change at the city limits. See how Michigan sets frost line depth.

How deep do footings, decks and water lines need to be in Farmington Hills?

House or garage footing Deck footing Water service line Fence post

House or garage footing in Farmington Hills: dig at least 42 in (107 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Minimum depths in Farmington Hills with a 42 in frost line
Project	Depth	Rule
House or garage footing	42 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	42 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	48 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	42 in	No code rule; common practice is below the frost line

Work out posts, concrete and footing sizes with the fence post depth calculator or the deck footing calculator.

How cold does it get in Farmington Hills?

Average lows are at or below freezing from Nov to Mar. 146 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 15.6 °F.

NOAA 1991–2020 climate normals, Farmington station, 1.5 mi away, elevation 720 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	15.6	15.7	24	34.1	45.8	56	59.8	58.9	51	39.9	29.7	21.8
High	30.4	33.7	43.6	56.7	68.5	78.4	82.9	80.7	73.5	60.3	46.7	35.4

Farmington Hills has more freezing nights than 40 of the 62 other Michigan places we track. The Michigan median is 143. Coldest: Marquette County; mildest: Allegan County.

How likely is the soil in Farmington Hills to heave?

Low 13%Moderate 38%High 49%

USDA rates the sampled soil around Farmington Hills as 13% low, 38% moderate, 49% high for frost action (main soils: Aquents, Marlette, Tedrow).

USDA NRCS soil survey, 9 sample points within 2 mi. Higher frost action means more risk of heave; see frost heave.

How do you confirm the frost line before you dig in Farmington Hills?

Call 811 (MISS DIG 811) at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Farmington Hills building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 42 in unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

Farmington Hills at a glance

Frost line depth: 42 in (Michigan rule)
County: Oakland County
Population (2023 est.): 82,528
Mean annual temperature: 47.6 °F
ZIP codes (7): 48025 · 48167 · 48322 · 48331 · 48334 · 48335 · 48336