Frost Line Depth in Bloomington, Illinois
- Bloomington’s adopted code
- Checked Oct 2026
- Sources
Verified
40in
102 cm · 3 ft 4 in
Set in the building code Bloomington has adopted.
Source and how we checked
Document: ecode360.com
Climate: 133 nights a year at or below 32 °F (NOAA 1991–2020, Normal 4Ne, 5.2 mi).
Checked Oct 2026. Report a correction
How deep is the frost line in Bloomington?
Bloomington's building authority sets the frost line depth at 40 in (102 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 Bloomington?
Illinois leaves the frost line depth to each city or county, and Bloomington fills it in when it adopts the residential code. The value above comes from Bloomington’s own document on ecode360.com. See how Illinois sets frost line depth.
How deep do footings, decks and water lines need to be in Bloomington?
House or garage footing in Bloomington: dig at least 40 in (102 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).
| Project | Depth | Rule |
|---|---|---|
| House or garage footing | 40 in | Below the frost line and at least 12 in deep (IRC R403.1.4) |
| Deck footing (attached) | 40 in | Below the frost line and at least 12 in deep (IRC R507.3) |
| Water service line | 46 in | 6 in below the frost line and at least 12 in deep (IRC P2603.5) |
| Fence post bottom | 40 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 Bloomington?
- J
- F
- M
- A
- M
- J
- J
- A
- S
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- N
- D
Average lows are at or below freezing from Nov to Mar. 133 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 15.6 °F.
NOAA 1991–2020 climate normals, Normal 4ne station, 5.2 mi away, elevation 790 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 15.6 | 18.9 | 27.8 | 37.9 | 49.8 | 59.9 | 63 | 60.8 | 53 | 41.8 | 30.7 | 21.4 |
| High | 33.4 | 38.2 | 49.8 | 62.8 | 74 | 83.3 | 86 | 84.4 | 78.8 | 65.6 | 50.2 | 38.3 |
Bloomington has more freezing nights than 46 of the 71 other Illinois places we track. The Illinois median is 127. Coldest: Hoffman Estates; mildest: Madison County.
What frost line depth do towns near Bloomington use?
3 official codes near Bloomington are verified; each links to its document.
| Place | Verified frost line | Distance |
|---|---|---|
| Decatur | 36 in | 43 mi away |
| Peoria County | 42 in | 47 mi away |
| LaSalle County | 42 in | 60 mi away |
How likely is the soil in Bloomington to heave?
USDA rates the sampled soil around Bloomington as 8% moderate, 92% high for frost action (main soils: Catlin, Saybrook, Osco).
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 Bloomington?
Bloomington at a glance
- Frost line depth
- 40 in
- County
- McLean County
- Population (2023 est.)
- 78,587
- Mean annual temperature
- 51.1 °F
- ZIP codes (4)
- 61701 · 61704 · 61705 · 61761