Frost Line Depth in Deschutes County, OR: 18 in (Oregon rule)

State-set value

18in

46 cm · 1 ft 6 in

18 in (Oregon rule)

Set by the state: Oregon Residential Specialty Code Table R301.2(1), Deschutes County.

Source and how we checked

Deschutes County does not publish its own value; the state rule applies.

Document: codes.iccsafe.org

Climate: 231 nights a year at or below 32 °F (NOAA 1991–2020, Sunriver, 9.4 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

231nights a year at or below 32 °F
67%of nearby soil rated “high” for frost action (USDA)

How deep is the frost line in Deschutes County?

Oregon sets the frost footing depth for Deschutes County at 18 in (46 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 Deschutes County?

Oregon writes this depth into its statewide residential code, so Deschutes 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 Deschutes County?

House or garage footing Deck footing Water service line Fence post

House or garage footing in Deschutes County: dig at least 18 in (46 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Minimum depths in Deschutes County with a 18 in frost line
Project	Depth	Rule
House or garage footing	18 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	18 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	24 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	18 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 Deschutes County?

Average lows are at or below freezing from Oct to Apr. 231 nights a year reach 32 °F or colder; Dec is coldest, with an average low of 19 °F.

NOAA 1991–2020 climate normals, Sunriver station, 9.4 mi away, elevation 4,180 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	19.6	21.1	24.2	24.6	32.9	37.2	41	40.1	34	27.8	24	19
High	39.8	43.1	49.7	56.6	64.7	72	84.1	83.1	75.8	61.9	46.3	37.5

Deschutes County has more freezing nights than 22 of the 22 other Oregon places we track. The Oregon median is 54. Coldest: Deschutes County; mildest: Lincoln County.

How likely is the soil in Deschutes County to heave?

Moderate 33%High 67%

USDA rates the sampled soil around Deschutes County as 33% moderate, 67% high for frost action (main soils: Wanoga, Henkle, Fremkle).

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 Deschutes County?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Deschutes County building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 18 in unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

Deschutes County at a glance

Frost line depth: 18 in (Oregon rule)
Population (2023 est.): 208,513
Mean annual temperature: 44.2 °F
ZIP codes (10): 97701 · 97702 · 97703 · 97707 · 97709 · 97712 · 97739 · 97756 · 97759 · 97760