Frost Line Depth in Sangamon County, Illinois
- 3 verified codes nearby
- Checked Oct 2026
No official local value
No official frost line depth is published for Sangamon County.
Nearby official codes require 36–42 in (3 verified codes).
Source and how we checked
We searched this place’s own code and website and found no published frost line depth.
Climate: 114 nights a year at or below 32 °F (NOAA 1991–2020, Springfield #2, 2.9 mi).
Checked Oct 2026. Report a correction
Does Sangamon County have an official frost line depth?
No adopted frost line depth found for Sangamon County in its official documents (checked Oct 2026). The nearest official values, from codes we verified, are 36 to 42 in. Use the deepest of them until the building department confirms Sangamon County’s own number.
What frost line depth does Sangamon County use for footings under Table R301.2(1)? Is it 36 in, like Decatur?
How deep do footings, decks and water lines need to be in Sangamon County?
Drawn with the deepest nearby official value (42 in). Confirm Sangamon County’s own depth before you dig.
House or garage footing in Sangamon County: dig at least 42 in (107 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).
| Project | Depth | Rule |
|---|---|---|
| House or garage footing | 42 in | Below the frost line and at least 12 in deep (IRC R403.1.4) |
| Deck footing (attached) | 42 in | Below the frost line and at least 12 in deep (IRC R507.3) |
| Water service line | 48 in | 6 in below the frost line and at least 12 in deep (IRC P2603.5) |
| Fence post bottom | 42 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 Sangamon County?
- J
- F
- M
- A
- M
- J
- J
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- S
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- D
Average lows are at or below freezing from Dec to Mar. 114 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 18.6 °F.
NOAA 1991–2020 climate normals, Springfield #2 station, 2.9 mi away, elevation 599 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 18.6 | 21.6 | 30.7 | 41.1 | 53 | 62.6 | 65.9 | 63.7 | 55.5 | 43.7 | 32.8 | 23.8 |
| High | 35.8 | 41.1 | 52.3 | 64.5 | 73.5 | 82.7 | 85.5 | 83.9 | 77.9 | 66.3 | 52.7 | 41.3 |
Sangamon County has fewer freezing nights than 53 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 Sangamon County use?
3 official codes near Sangamon County are verified; each links to its document.
| Place | Verified frost line | Distance |
|---|---|---|
| Decatur | 36 in | 39 mi away |
| Bloomington | 40 in | 62 mi away |
| Peoria County | 42 in | 71 mi away |
How likely is the soil in Sangamon County to heave?
USDA rates the sampled soil around Sangamon County as 32% moderate, 68% high for frost action (main soils: Sable, Ipava, Hartsburg).
USDA NRCS soil survey, 9 sample points within 2 mi. Higher frost action means more risk of heave; see frost heave.
Sangamon County at a glance
- Frost line depth
- No official local value
- Population (2023 est.)
- 193,491
- Mean annual temperature
- 52.9 °F
- ZIP codes (30)
- 62515 · 62520 · 62530 · 62536 · 62539 · 62545 · 62548 · 62558 · 62561 · 62563 · 62613 · 62615 · 62625 · 62629 · 62661 · 62670 · 62677 · 62684 · 62689 · 62690 · 62692 · 62693 · 62701 · 62702 · 62703 · 62704 · 62706 · 62707 · 62711 · 62712