Clallam County, WA Frost Line Depth: 12 in

Verified

12in

30 cm · 1 ft

Set in the building code Clallam County has adopted.

Source and how we checked

Document: clallamcountywa.gov

Climate: 66 nights a year at or below 32 °F (NOAA 1991–2020, Elwha Rs, 15.3 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

2 of 2nearby verified codes use the same depth
66nights a year at or below 32 °F
52%of nearby soil rated “low” for frost action (USDA)

How deep is the frost line in Clallam County?

"{confirmed quote}". Footings, piers and other permanent supports must reach at least this depth (IRC R403.1.4.1).

Who sets the frost line depth in Clallam County?

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

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

House or garage footing Deck footing Water service line Fence post

House or garage footing in Clallam County: dig at least 12 in (30 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Minimum depths in Clallam County with a 12 in frost line
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 Clallam County?

Clallam County never averages a low below freezing. 66 nights a year reach 32 °F or colder; Dec is coldest, with an average low of 32.7 °F.

NOAA 1991–2020 climate normals, Elwha Rs station, 15.3 mi away, elevation 360 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	32.8	32.8	34.9	37.8	43.2	47.2	50.7	51.6	48	41.5	36.1	32.7
High	41.1	43.8	49.7	56.3	63.4	67.2	73.6	74.5	68.1	55.5	45.6	40.7

Clallam County has more freezing nights than 26 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 Clallam County use?

2 official codes near Clallam County are verified; each links to its document.

Official frost line depths near Clallam County
Place	Verified frost line	Distance
Mason County	12 in	62 mi away
Bremerton	12 in	67 mi away

How likely is the soil in Clallam County to heave?

Low 52%Moderate 41%

USDA rates the sampled soil around Clallam County as 2% none, 52% low, 41% moderate, 5% high for frost action (main soils: Sadie, Terbies, Skookumcreek).

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 Clallam County?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Clallam County building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 12 in unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

Clallam County at a glance

Frost line depth: 12 in
Population (2023 est.): 77,616
Mean annual temperature: 48.7 °F
ZIP codes (9): 98305 · 98326 · 98331 · 98350 · 98357 · 98362 · 98363 · 98381 · 98382