Frost Line Depth in Fort Collins, Colorado
- Fort Collins’s adopted code
- Checked Oct 2026
- Sources
Verified
30in
76 cm · 2 ft 6 in
Set in the building code Fort Collins has adopted.
Source and how we checked
Document: fortcollins.gov
Climate: 150 nights a year at or below 32 °F (NOAA 1991–2020, Ft Collins, 2.2 mi).
Checked Oct 2026. Report a correction
How deep is the frost line in Fort Collins?
"{confirmed quote}". Footings, piers and other permanent supports must reach at least this depth (IRC R403.1.4.1).
Who sets the frost line depth in Fort Collins?
Colorado leaves the frost line depth to each city or county, and Fort Collins fills it in when it adopts the residential code. The value above comes from Fort Collins’s own document on fortcollins.gov. Larimer County uses the same 30 in, so the depth does not change at the city limits. See how Colorado sets frost line depth.
How deep do footings, decks and water lines need to be in Fort Collins?
House or garage footing in Fort Collins: dig at least 30 in (76 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).
| 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 Fort Collins?
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Average lows are at or below freezing from Nov to Mar. 150 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 18.3 °F.
NOAA 1991–2020 climate normals, Ft Collins station, 2.2 mi away, elevation 5,004 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 18.3 | 20.7 | 28.5 | 35.4 | 44.1 | 52.8 | 58.7 | 56.5 | 48 | 36.1 | 26.1 | 18.3 |
| High | 45 | 46.8 | 56.4 | 62.5 | 70.9 | 81.8 | 87.4 | 85 | 77.4 | 64.3 | 52.5 | 44 |
Fort Collins has fewer freezing nights than 11 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 Fort Collins use?
2 official codes near Fort Collins are verified; each links to its document.
| Place | Verified frost line | Distance |
|---|---|---|
| Larimer County | 30 in | 23 mi away |
| Broomfield | 36 in | 41 mi away |
How likely is the soil in Fort Collins to heave?
USDA rates the sampled soil around Fort Collins as 64% low, 36% moderate for frost action (main soils: Nunn, Fort Collins, Satanta).
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 Fort Collins?
Fort Collins at a glance
- Frost line depth
- 30 in
- County
- Larimer County
- Population (2023 est.)
- 170,376
- Mean annual temperature
- 50.7 °F
- ZIP codes (7)
- 80512 · 80521 · 80524 · 80525 · 80526 · 80528 · 80547