Boone County, MO Frost Line Depth: 30 in

Verified

30in

76 cm · 2 ft 6 in

Set in the building code Boone County has adopted.

Source and how we checked

Document: boonemo.gov

Climate: 93 nights a year at or below 32 °F (NOAA 1991–2020, Columbia U Of M, 3.3 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

93nights a year at or below 32 °F
52%of nearby soil rated “moderate” for frost action (USDA)

How deep is the frost line in Boone County?

Boone County's building authority sets the frost line depth at 30 in (76 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 Boone County?

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

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

House or garage footing Deck footing Water service line Fence post

House or garage footing in Boone County: dig at least 30 in (76 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Minimum depths in Boone County with a 30 in frost line
Project	Depth	Rule
House or garage footing	30 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	30 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	36 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	30 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 Boone County?

Average lows are at or below freezing from Dec to Feb. 93 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 22.5 °F.

NOAA 1991–2020 climate normals, Columbia U Of M station, 3.3 mi away, elevation 770 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	22.5	26.5	35.8	45.8	56	65.2	69.1	67.4	58.8	47.3	36.5	26.9
High	39.3	44.9	56.2	67	75.7	84.5	88.6	87.6	79.9	68.3	54.8	43.6

Boone County has fewer freezing nights than 8 of the 11 other Missouri places we track. The Missouri median is 105. Coldest: Buchanan County; mildest: Camden County.

How likely is the soil in Boone County to heave?

None 13%Moderate 52%High 35%

USDA rates the sampled soil around Boone County as 13% none, 52% moderate, 35% high for frost action (main soils: Keswick, Urban land, Leonard).

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 Boone County?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Boone County building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 30 in unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

Boone County at a glance

Frost line depth: 30 in
Population (2023 est.): 189,463
Mean annual temperature: 56.2 °F
ZIP codes (14): 65010 · 65039 · 65063 · 65201 · 65202 · 65203 · 65215 · 65216 · 65240 · 65243 · 65255 · 65256 · 65279 · 65284