Roanoke County, VA Frost Line Depth: 24 in

Verified

24in

61 cm · 2 ft

Set in the building code Roanoke County has adopted.

Source and how we checked

Document: roanokecountyva.gov

Climate: 77 nights a year at or below 32 °F (NOAA 1991–2020, Roanoke Regional Airport, 12 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

77nights a year at or below 32 °F
87%of nearby soil rated “moderate” for frost action (USDA)

How deep is the frost line in Roanoke County?

Roanoke County's building authority sets the frost line depth at 24 in (61 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 Roanoke County?

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

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

House or garage footing Deck footing Water service line Fence post

House or garage footing in Roanoke County: dig at least 24 in (61 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Minimum depths in Roanoke County with a 24 in frost line
Project	Depth	Rule
House or garage footing	24 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	24 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	30 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	24 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 Roanoke County?

Average lows are at or below freezing from Dec to Feb. 77 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 28.7 °F.

NOAA 1991–2020 climate normals, Roanoke Regional Airport station, 12 mi away, elevation 1,175 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	28.7	30.8	37.6	46.3	55	63.2	67.4	66	59.1	47.8	37.7	31.8
High	47.1	50.8	59	69.7	77.2	84.4	88.1	86.5	80	70.1	59	50

Roanoke County has fewer freezing nights than 13 of the 22 other Virginia places we track. The Virginia median is 94. Coldest: Shenandoah County; mildest: Norfolk.

How likely is the soil in Roanoke County to heave?

Low 12%Moderate 87%

USDA rates the sampled soil around Roanoke County as 12% low, 87% moderate, 1% high for frost action (main soils: Frederick, Dekalb, Chilhowie).

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 Roanoke County?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Roanoke County building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 24 in unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

Roanoke County at a glance

Frost line depth: 24 in
Population (2023 est.): 97,026
Mean annual temperature: 58.1 °F
ZIP codes (14): 24012 · 24014 · 24015 · 24018 · 24019 · 24020 · 24059 · 24065 · 24070 · 24087 · 24101 · 24153 · 24175 · 24179