Douglas County, WA Frost Line Depth: 24 in

Verified

24in

61 cm · 2 ft

Set in the building code Douglas County has adopted.

Source and how we checked

Document: douglascountywa.gov

Climate: 109 nights a year at or below 32 °F (NOAA 1991–2020, Chelan, 15.6 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

1 of 1nearby verified codes use the same depth
109nights a year at or below 32 °F
68%of nearby soil rated “high” for frost action (USDA)

How deep is the frost line in Douglas County?

Douglas County's building authority sets the frost line depth at 24 in (61 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 Douglas County?

Washington leaves the frost line depth to each city or county, and Douglas County fills it in when it adopts the residential code. The value above comes from Douglas County’s own document on douglascountywa.gov. See how Washington sets frost line depth.

How deep do footings, decks and water lines need to be in Douglas County?

House or garage footing Deck footing Water service line Fence post

House or garage footing in Douglas County: dig at least 24 in (61 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Minimum depths in Douglas County with a 24 in frost line
Project	Depth	Rule
House or garage footing	24 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	24 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	30 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	24 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 Douglas County?

Average lows are at or below freezing from Nov to Mar. 109 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 21.6 °F.

NOAA 1991–2020 climate normals, Chelan station, 15.6 mi away, elevation 1,194 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	21.6	24.3	30.3	37.5	46.2	53	59.1	58.1	49.2	38.8	29.5	22.6
High	34.3	41.7	51.9	62.1	71.9	77.9	86.6	87	77.2	62.2	45.7	34.9

Douglas County has more freezing nights than 35 of the 47 other Washington places we track. The Washington median is 54. Coldest: Chelan County; mildest: Lakewood.

What frost line depth do towns near Douglas County use?

One official code near Douglas County is verified.

Official frost line depths near Douglas County
Place	Verified frost line	Distance
Okanogan County	24 in	56 mi away

How likely is the soil in Douglas County to heave?

Moderate 30%High 68%

USDA rates the sampled soil around Douglas County as 2% none, 30% moderate, 68% high for frost action (main soils: Touhey, Stubblefield, Strat).

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 Douglas County?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Douglas County building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 24 in unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

Douglas County at a glance

Frost line depth: 24 in
Population (2023 est.): 44,798
Mean annual temperature: 50.1 °F
ZIP codes (13): 98802 · 98812 · 98813 · 98823 · 98830 · 98843 · 98845 · 98848 · 98850 · 98858 · 99115 · 99116 · 99133