Cedar Rapids, IA Frost Line Depth: 42 in

Verified

42in

107 cm · 3 ft 6 in

Set in the building code Cedar Rapids has adopted.

Source and how we checked

Document: library.municode.com

Climate: 144 nights a year at or below 32 °F (NOAA 1991–2020, Cedar Rapids Municipal Airport, 6 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

1 of 1nearby verified codes use the same depth
144nights a year at or below 32 °F
50%of nearby soil rated “moderate” for frost action (USDA)

How deep is the frost line in Cedar Rapids?

Cedar Rapids' 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 Cedar Rapids?

Iowa leaves the frost line depth to each city or county, and Cedar Rapids fills it in when it adopts the residential code. The value above comes from Cedar Rapids’s own document on library.municode.com. Linn County uses the same 42 in, so the depth does not change at the city limits. See how Iowa sets frost line depth.

How deep do footings, decks and water lines need to be in Cedar Rapids?

House or garage footing Deck footing Water service line Fence post

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

Minimum depths in Cedar Rapids 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 Cedar Rapids?

Average lows are at or below freezing from Nov to Mar. 144 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 11.3 °F.

NOAA 1991–2020 climate normals, Cedar Rapids Municipal Airport station, 6 mi away, elevation 868 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	11.3	15.5	26.8	37.6	49.5	59.7	62.7	60.4	51.9	39.9	27.7	17.1
High	27.9	32.6	46.3	60.1	71.1	80.1	82.8	81.2	74.7	61.5	46.2	33.3

Cedar Rapids has fewer freezing nights than 14 of the 28 other Iowa places we track. The Iowa median is 144. Coldest: Cerro Gordo County; mildest: Davenport.

What frost line depth do towns near Cedar Rapids use?

One official code near Cedar Rapids is verified.

Official frost line depths near Cedar Rapids
Place	Verified frost line	Distance
Linn County	42 in	9 mi away

How likely is the soil in Cedar Rapids to heave?

Low 16%Moderate 50%High 33%

USDA rates the sampled soil around Cedar Rapids as 16% low, 50% moderate, 33% high for frost action (main soils: Anthroportic Udorthents, Waukegan, Fayette).

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 Cedar Rapids?

Call 811 (Iowa One Call) at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Cedar Rapids 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.

Cedar Rapids at a glance

Frost line depth: 42 in
County: Linn County
Population (2023 est.): 135,958
Mean annual temperature: 48.3 °F
ZIP codes (12): 52227 · 52228 · 52233 · 52302 · 52324 · 52328 · 52401 · 52402 · 52403 · 52404 · 52405 · 52411