Frost Line Depth in Eau Claire, WI: 48 in (Wisconsin rule)

State-set value

48in

122 cm · 4 ft

48 in (Wisconsin rule)

Set by the state: Wisconsin Uniform Dwelling Code SPS 321.16 (minimum; deeper where frost goes deeper).

Source and how we checked

Eau Claire does not publish its own value; the state rule applies.

Document: docs.legis.wisconsin.gov

Climate: 148 nights a year at or below 32 °F (NOAA 1991–2020, Eau Claire 3Sw, 2.4 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

1 of 1nearby verified codes use the same depth
148nights a year at or below 32 °F
71%of nearby soil rated “low” for frost action (USDA)

How deep is the frost line in Eau Claire?

Wisconsin sets the frost footing depth for Eau Claire at 48 in (122 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 Eau Claire?

Wisconsin writes this depth into its statewide residential code, so Eau Claire’s building department enforces the state’s number rather than setting its own. Eau Claire County uses the same 48 in, so the depth does not change at the city limits. See how Wisconsin sets frost line depth.

How deep do footings, decks and water lines need to be in Eau Claire?

House or garage footing Deck footing Water service line Fence post

House or garage footing in Eau Claire: dig at least 48 in (122 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Minimum depths in Eau Claire with a 48 in frost line
Project	Depth	Rule
House or garage footing	48 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	48 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	54 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	48 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 Eau Claire?

Average lows are at or below freezing from Nov to Mar. 148 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 7.9 °F.

NOAA 1991–2020 climate normals, Eau Claire 3sw station, 2.4 mi away, elevation 880 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	7.9	11.7	23.9	35.9	48.6	58.2	62.1	61	51.7	39.7	26.9	14.8
High	24.5	28.7	41.6	56.4	69.3	77.8	82.3	79.9	71.8	58.2	41.8	29.7

Eau Claire has fewer freezing nights than 28 of the 52 other Wisconsin places we track. The Wisconsin median is 150. Coldest: Marinette County; mildest: Racine.

What frost line depth do towns near Eau Claire use?

One official code near Eau Claire is verified.

Official frost line depths near Eau Claire
Place	Verified frost line	Distance
Chippewa County	48 in	20 mi away

How likely is the soil in Eau Claire to heave?

Low 71%Moderate 29%

USDA rates the sampled soil around Eau Claire as 71% low, 29% moderate for frost action (main soils: Plainfield, Elkmound, Meridian).

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 Eau Claire?

Call 811 (Diggers Hotline) at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Eau Claire building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 48 in unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

Eau Claire at a glance

Frost line depth: 48 in (Wisconsin rule)
County: Eau Claire County
Population (2023 est.): 70,542
Mean annual temperature: 46 °F
ZIP codes (4): 54701 · 54703 · 54720 · 54729