Sioux Falls, SD Frost Line Depth: 42 in

Verified

42in

107 cm · 3 ft 6 in

Set in the building code Sioux Falls has adopted.

Source and how we checked

Document: codelibrary.amlegal.com

Climate: 154 nights a year at or below 32 °F (NOAA 1991–2020, Sioux Falls Wfo Airport, 3.3 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

154nights a year at or below 32 °F
61%of nearby soil rated “high” for frost action (USDA)

How deep is the frost line in Sioux Falls?

Sioux Falls' building authority sets the frost line depth at 42 in (107 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 Sioux Falls?

South Dakota has no statewide residential code, so Sioux Falls adopts its own and fills in the frost line depth. The value above comes from Sioux Falls’s own document on codelibrary.amlegal.com. See how South Dakota sets frost line depth.

How deep do footings, decks and water lines need to be in Sioux Falls?

House or garage footing Deck footing Water service line Fence post

House or garage footing in Sioux Falls: dig at least 42 in (107 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Minimum depths in Sioux Falls with a 42 in frost line
Project	Depth	Rule
House or garage footing	42 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	42 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	48 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	42 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 Sioux Falls?

Average lows are at or below freezing from Nov to Mar. 154 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 7.4 °F.

NOAA 1991–2020 climate normals, Sioux Falls Wfo Airport station, 3.3 mi away, elevation 1,430 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	7.4	11.4	23.4	35.5	48.5	59.3	63.7	61.2	51.7	37.8	24.2	12.5
High	25.3	30	43.3	57	69.9	80.4	84.8	81.7	74.8	60.6	43.6	30.4

How likely is the soil in Sioux Falls to heave?

Moderate 30%High 61%

USDA rates the sampled soil around Sioux Falls as 9% low, 30% moderate, 61% high for frost action (main soils: Clamo, Lamo, Davis).

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 Sioux Falls?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Sioux Falls building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 42 in unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

Sioux Falls at a glance

Frost line depth: 42 in
County: Minnehaha County
Population (2023 est.): 206,410
Mean annual temperature: 46.6 °F
ZIP codes (10): 57005 · 57103 · 57104 · 57105 · 57106 · 57107 · 57108 · 57110 · 57117 · 57197