Frost Line Depth in Larimer County, Colorado
- Larimer County’s adopted code
- Checked Oct 2026
- Sources
Verified
30in
76 cm · 2 ft 6 in
Set in the building code Larimer County has adopted.
Source and how we checked
Document: larimer.gov
Climate: 241 nights a year at or below 32 °F (NOAA 1991–2020, Hourglass Rsvr, 9.2 mi).
Checked Oct 2026. Report a correction
How deep is the frost line in Larimer County?
Larimer 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 Larimer County?
Colorado leaves the frost line depth to each city or county, and Larimer County fills it in when it adopts the residential code. The value above comes from Larimer County’s own document on larimer.gov. See how Colorado sets frost line depth.
How deep do footings, decks and water lines need to be in Larimer County?
House or garage footing in Larimer County: 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 Larimer County?
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Average lows are at or below freezing from Oct to May. 241 nights a year reach 32 °F or colder; Feb is coldest, with an average low of 10 °F.
NOAA 1991–2020 climate normals, Hourglass Rsvr station, 9.2 mi away, elevation 9,520 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 10.8 | 10 | 15.3 | 20 | 28 | 36.4 | 42.8 | 41.1 | 34.3 | 25.5 | 17.7 | 10.8 |
| High | 31 | 32.7 | 40.1 | 45.1 | 55.3 | 68.1 | 74.3 | 71.6 | 64.8 | 51.3 | 39 | 31 |
Larimer County has more freezing nights than 13 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 Larimer County use?
2 official codes near Larimer County are verified; each links to its document.
| Place | Verified frost line | Distance |
|---|---|---|
| Fort Collins | 30 in | 23 mi away |
| Broomfield | 36 in | 54 mi away |
How likely is the soil in Larimer County to heave?
USDA rates the sampled soil around Larimer County as 19% none, 81% moderate for frost action (main soils: Bullwark family, Rock outcrop, Catamount family).
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 Larimer County?
Larimer County at a glance
- Frost line depth
- 30 in
- Population (2023 est.)
- 370,771
- Mean annual temperature
- 37.4 °F
- ZIP codes (24)
- 80503 · 80504 · 80512 · 80513 · 80515 · 80517 · 80521 · 80524 · 80525 · 80526 · 80528 · 80532 · 80534 · 80535 · 80536 · 80537 · 80538 · 80540 · 80545 · 80547 · 80549 · 80550 · 80612 · 82063