Arapahoe County, CO Frost Line Depth: 36 in

Verified

36in

91 cm · 3 ft

Set in the building code Arapahoe County has adopted.

Source and how we checked

Document: arapahoeco.gov

Climate: 176 nights a year at or below 32 °F (NOAA 1991–2020, Byers 5 Ene, 12.7 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

1 of 1nearby verified codes use the same depth
176nights a year at or below 32 °F
65%of nearby soil rated “moderate” for frost action (USDA)

How deep is the frost line in Arapahoe County?

Arapahoe County's building authority sets the frost line depth at 36 in (91 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 Arapahoe County?

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

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

House or garage footing Deck footing Water service line Fence post

House or garage footing in Arapahoe County: dig at least 36 in (91 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Minimum depths in Arapahoe County with a 36 in frost line
Project	Depth	Rule
House or garage footing	36 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	36 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	42 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	36 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 Arapahoe County?

Average lows are at or below freezing from Nov to Apr. 176 nights a year reach 32 °F or colder; Dec is coldest, with an average low of 13.8 °F.

NOAA 1991–2020 climate normals, Byers 5 Ene station, 12.7 mi away, elevation 5,101 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	14.2	15.8	24.7	31.5	41.5	50.9	57.4	55.6	46.5	33.2	22.2	13.8
High	42.3	44.6	54.3	61.2	70.5	82.9	89.5	87	79.3	65.2	52.5	42.5

Arapahoe County has fewer freezing nights than 7 of the 14 other Colorado places we track. The Colorado median is 176. Coldest: Eagle County; mildest: Littleton.

What frost line depth do towns near Arapahoe County use?

One official code near Arapahoe County is verified.

Official frost line depths near Arapahoe County
Place	Verified frost line	Distance
Douglas County	36 in	39 mi away

How likely is the soil in Arapahoe County to heave?

Low 35%Moderate 65%

USDA rates the sampled soil around Arapahoe County as 35% low, 65% moderate for frost action (main soils: Bresser, Bijou, Nunn).

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 Arapahoe County?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Arapahoe County building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 36 in unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

Arapahoe County at a glance

Frost line depth: 36 in
Population (2023 est.): 656,061
Mean annual temperature: 49.1 °F
ZIP codes (33): 80010 · 80011 · 80012 · 80013 · 80014 · 80015 · 80016 · 80017 · 80018 · 80102 · 80103 · 80105 · 80110 · 80111 · 80112 · 80113 · 80120 · 80121 · 80122 · 80123 · 80128 · 80129 · 80136 · 80137 · 80220 · 80222 · 80224 · 80230 · 80231 · 80236 · 80237 · 80246 · 80247