Frost Line Depth in Spokane Valley, Washington
- Spokane Valley’s adopted code
- Checked Oct 2026
- Sources
Verified
24in
61 cm · 2 ft
Set in the building code Spokane Valley has adopted.
Source and how we checked
Document: ecode360.com
Climate: 123 nights a year at or below 32 °F (NOAA 1991–2020, Spokane Felts Fld, 4.3 mi).
Checked Oct 2026. Report a correction
How deep is the frost line in Spokane Valley?
Spokane Valley's building authority sets the frost line depth at 24 in (61 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 Spokane Valley?
Washington leaves the frost line depth to each city or county, and Spokane Valley fills it in when it adopts the residential code. The value above comes from Spokane Valley’s own document on ecode360.com. Spokane County uses the same 24 in, so the depth does not change at the city limits. See how Washington sets frost line depth.
How deep do footings, decks and water lines need to be in Spokane Valley?
House or garage footing in Spokane Valley: dig at least 24 in (61 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).
| Project | Depth | Rule |
|---|---|---|
| House or garage footing | 24 in | Below the frost line and at least 12 in deep (IRC R403.1.4) |
| Deck footing (attached) | 24 in | Below the frost line and at least 12 in deep (IRC R507.3) |
| Water service line | 30 in | 6 in below the frost line and at least 12 in deep (IRC P2603.5) |
| Fence post bottom | 24 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 Spokane Valley?
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Average lows are at or below freezing from Nov to Mar. 123 nights a year reach 32 °F or colder; Dec is coldest, with an average low of 25.7 °F.
NOAA 1991–2020 climate normals, Spokane Felts Fld station, 4.3 mi away, elevation 1,953 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 25.8 | 26.7 | 31.7 | 36.6 | 44.1 | 50.4 | 56 | 54.5 | 46.8 | 38 | 30.7 | 25.7 |
| High | 37.8 | 42.5 | 51.3 | 59.6 | 69.7 | 75.8 | 87.1 | 86.2 | 76 | 60.3 | 45.1 | 36.9 |
Spokane Valley has more freezing nights than 41 of the 47 other Washington places we track. The Washington median is 54. Coldest: Chelan County; mildest: Lakewood.
What frost line depth do towns near Spokane Valley use?
One official code near Spokane Valley is verified.
| Place | Verified frost line | Distance |
|---|---|---|
| Spokane County | 24 in | 8 mi away |
How likely is the soil in Spokane Valley to heave?
USDA rates the sampled soil around Spokane Valley as 17% low, 77% moderate, 6% high for frost action (main soils: Opportunity, Narcisse, Marble).
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 Spokane Valley?
Spokane Valley at a glance
- Frost line depth
- 24 in
- County
- Spokane County
- Population (2023 est.)
- 108,235
- Mean annual temperature
- 49.8 °F
- ZIP codes (7)
- 99016 · 99027 · 99037 · 99202 · 99206 · 99212 · 99216