Eagle County, CO Frost Line Depth: 48 in

Verified

48in

122 cm · 4 ft

Set in the building code Eagle County has adopted.

Source and how we checked

Document: eaglecounty.us

Climate: 248 nights a year at or below 32 °F (NOAA 1991–2020, Vail, 18.2 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

248nights a year at or below 32 °F
45%of nearby soil rated “moderate” for frost action (USDA)

How deep is the frost line in Eagle County?

Eagle County's building authority sets the frost line depth 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 Eagle County?

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

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

House or garage footing Deck footing Water service line Fence post

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

Minimum depths in Eagle County 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 Eagle County?

Average lows are at or below freezing from Oct to May. 248 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 6.6 °F.

NOAA 1991–2020 climate normals, Vail station, 18.2 mi away, elevation 8,305 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	6.6	9.2	16.7	23.8	31	35.6	41.6	40.8	34	25.2	15.1	7.1
High	28.5	33	41.7	49.4	60.4	71.4	76.7	74	66.6	54.1	37.7	28

Eagle County has more freezing nights than 14 of the 14 other Colorado places we track. The Colorado median is 176. Coldest: Eagle County; mildest: Littleton.

How likely is the soil in Eagle County to heave?

None 22%Low 32%Moderate 45%

USDA rates the sampled soil around Eagle County as 22% none, 32% low, 45% moderate for frost action (main soils: Mord family, Moyerson, Rock outcrop).

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 Eagle County?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Eagle County 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.

Eagle County at a glance

Frost line depth: 48 in
Population (2023 est.): 54,381
Mean annual temperature: 37.9 °F
ZIP codes (13): 80423 · 80426 · 80463 · 81620 · 81621 · 81623 · 81631 · 81632 · 81637 · 81645 · 81649 · 81655 · 81657