Frost Line Depth in Antioch, California
- 5 verified codes nearby
- Checked Oct 2026
No official local value
No official frost line depth is published for Antioch.
Nearby official codes require 5–30 in (5 verified codes).
Source and how we checked
We searched this place’s own code and website and found no published frost line depth.
Climate: 7 nights a year at or below 32 °F (NOAA 1991–2020, Antioch Pumping Plt #3, 2.4 mi).
Checked Oct 2026. Report a correction
Does Antioch have an official frost line depth?
No adopted frost line depth found for Antioch in its official documents (checked Oct 2026). The nearest official values, from codes we verified, are 5 to 30 in. Use the deepest of them until the building department confirms Antioch’s own number.
What frost line depth does Antioch use for footings under Table R301.2(1)? Is it 30 in, like Brentwood?
How deep do footings, decks and water lines need to be in Antioch?
Drawn with the deepest nearby official value (30 in). Confirm Antioch’s own depth before you dig.
House or garage footing in Antioch: 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 Antioch?
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Antioch never averages a low below freezing. 7 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 40.3 °F.
NOAA 1991–2020 climate normals, Antioch Pumping Plt #3 station, 2.4 mi away, elevation 60 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 40.3 | 43.9 | 46.6 | 49.5 | 54.3 | 59 | 60.6 | 60.3 | 58.7 | 54.2 | 46.2 | 40.4 |
| High | 55.7 | 60.8 | 66.5 | 72.1 | 79 | 86.3 | 91.4 | 90.2 | 86.7 | 77.5 | 64.6 | 55.8 |
Antioch has more freezing nights than 122 of the 208 other California places we track. The California median is 3. Coldest: El Dorado County; mildest: San Diego.
What frost line depth do towns near Antioch use?
5 official codes near Antioch are verified; each links to its document.
How likely is the soil in Antioch to heave?
USDA rates the sampled soil around Antioch as 100% none for frost action (main soils: Rincon, Capay, Cropley).
USDA NRCS soil survey, 9 sample points within 2 mi. Higher frost action means more risk of heave; see frost heave.
Antioch at a glance
- Frost line depth
- No official local value
- County
- Contra Costa County
- Population (2023 est.)
- 117,096
- Mean annual temperature
- 62.5 °F
- ZIP codes (5)
- 94509 · 94513 · 94531 · 94561 · 94565