Frost Line Depth in Ottawa County, Michigan
- Michigan state rule
- Checked Oct 2026
- Sources
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
Ottawa County does not publish its own value; the state rule applies.
Document: codes.iccsafe.org
Climate: 134 nights a year at or below 32 °F (NOAA 1991–2020, Grand Haven Wwtp, 0.8 mi).
Checked Oct 2026. Report a correction
How deep is the frost line in Ottawa County?
Michigan sets the frost footing depth for Ottawa County 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 Ottawa County?
Michigan writes this depth into its statewide residential code, so Ottawa County’s building department enforces the state’s number rather than setting its own. See how Michigan sets frost line depth.
How deep do footings, decks and water lines need to be in Ottawa County?
House or garage footing in Ottawa County: dig at least 42 in (107 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).
| 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 Ottawa County?
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Average lows are at or below freezing from Dec to Mar. 134 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 19.3 °F.
NOAA 1991–2020 climate normals, Grand Haven Wwtp station, 0.8 mi away, elevation 605 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 19.3 | 19.5 | 25.5 | 35.8 | 46.9 | 56.9 | 61.9 | 59.8 | 52.5 | 42.5 | 32.8 | 25.2 |
| High | 31.7 | 33.2 | 42.4 | 54.7 | 67.1 | 76.4 | 80 | 78.9 | 72.9 | 60 | 46.7 | 36.5 |
Ottawa County has fewer freezing nights than 44 of the 62 other Michigan places we track. The Michigan median is 143. Coldest: Marquette County; mildest: Allegan County.
What frost line depth do towns near Ottawa County use?
One official code near Ottawa County is verified.
| Place | Verified frost line | Distance |
|---|---|---|
| Montcalm County | 42 in | 57 mi away |
How likely is the soil in Ottawa County to heave?
USDA rates the sampled soil around Ottawa County as 74% low, 25% moderate, 1% high for frost action (main soils: Plainfield, Granby, Croswell).
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 Ottawa County?
Ottawa County at a glance
- Frost line depth
- 42 in (Michigan rule)
- Population (2023 est.)
- 303,372
- Mean annual temperature
- 48.3 °F
- ZIP codes (25)
- 49315 · 49318 · 49323 · 49330 · 49401 · 49403 · 49404 · 49409 · 49415 · 49417 · 49418 · 49423 · 49424 · 49426 · 49428 · 49430 · 49434 · 49435 · 49448 · 49451 · 49456 · 49460 · 49464 · 49534 · 49544