Frost Line Depth in Benton County, Oregon
- Oregon state rule
- Checked Oct 2026
- Sources
State-set value
12in
30 cm · 1 ft
12 in (Oregon rule)
Set by the state: Oregon Residential Specialty Code Table R301.2(1), Benton County.
Source and how we checked
Benton County does not publish its own value; the state rule applies.
Document: codes.iccsafe.org
Climate: 83 nights a year at or below 32 °F (NOAA 1991–2020, Corvallis Water Bureau, 1.9 mi).
Checked Oct 2026. Report a correction
How deep is the frost line in Benton County?
Oregon sets the frost footing depth for Benton County at 12 in (30 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 Benton County?
Oregon writes this depth into its statewide residential code, so Benton County’s building department enforces the state’s number rather than setting its own. See how Oregon sets frost line depth.
How deep do footings, decks and water lines need to be in Benton County?
House or garage footing in Benton County: dig at least 12 in (30 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).
| Project | Depth | Rule |
|---|---|---|
| House or garage footing | 12 in | Below the frost line and at least 12 in deep (IRC R403.1.4) |
| Deck footing (attached) | 12 in | Below the frost line and at least 12 in deep (IRC R507.3) |
| Water service line | 18 in | 6 in below the frost line and at least 12 in deep (IRC P2603.5) |
| Fence post bottom | 12 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 Benton County?
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Average lows are at or below freezing from Nov to Mar. 83 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 27.8 °F.
NOAA 1991–2020 climate normals, Corvallis Water Bureau station, 1.9 mi away, elevation 592 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 27.8 | 28.3 | 30.5 | 33 | 38.6 | 42.6 | 45.7 | 45.7 | 42.3 | 36.3 | 30.7 | 28.3 |
| High | 47.1 | 51.1 | 56.2 | 61.4 | 68.9 | 73.9 | 82.4 | 83 | 77.4 | 65 | 52.7 | 46.1 |
Benton County has more freezing nights than 17 of the 22 other Oregon places we track. The Oregon median is 54. Coldest: Deschutes County; mildest: Lincoln County.
What frost line depth do towns near Benton County use?
2 official codes near Benton County are verified; each links to its document.
| Place | Verified frost line | Distance |
|---|---|---|
| Corvallis | 12 in | 9 mi away |
| Marion County | 12 in | 50 mi away |
How likely is the soil in Benton County to heave?
USDA rates the sampled soil around Benton County as 88% none, 12% low for frost action (main soils: Jory, Gelderman, Willakenzie).
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 Benton County?
Benton County at a glance
- Frost line depth
- 12 in (Oregon rule)
- Population (2023 est.)
- 97,713
- Mean annual temperature
- 49.8 °F
- ZIP codes (10)
- 97321 · 97324 · 97326 · 97330 · 97331 · 97333 · 97361 · 97370 · 97448 · 97456