Frost Line Depth in Sammamish, Washington
- 5 verified codes nearby
- Checked Oct 2026
No official local value
No official frost line depth is published for Sammamish.
Nearby official codes require 12–18 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: 54 nights a year at or below 32 °F (NOAA 1991–2020, Snoqualmie Falls, 10.1 mi).
Checked Oct 2026. Report a correction
Does Sammamish have an official frost line depth?
No adopted frost line depth found for Sammamish in its official documents (checked Oct 2026). The nearest official values, from codes we verified, are 12 to 18 in. Use the deepest of them until the building department confirms Sammamish’s own number.
What frost line depth does Sammamish use for footings under Table R301.2(1)? Is it 12 in, like Redmond?
How deep do footings, decks and water lines need to be in Sammamish?
Drawn with the deepest nearby official value (18 in). Confirm Sammamish’s own depth before you dig.
House or garage footing in Sammamish: dig at least 18 in (46 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).
| Project | Depth | Rule |
|---|---|---|
| House or garage footing | 18 in | Below the frost line and at least 12 in deep (IRC R403.1.4) |
| Deck footing (attached) | 18 in | Below the frost line and at least 12 in deep (IRC R507.3) |
| Water service line | 24 in | 6 in below the frost line and at least 12 in deep (IRC P2603.5) |
| Fence post bottom | 18 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 Sammamish?
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Sammamish never averages a low below freezing. 54 nights a year reach 32 °F or colder; Feb is coldest, with an average low of 35.3 °F.
NOAA 1991–2020 climate normals, Snoqualmie Falls station, 10.1 mi away, elevation 440 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 35.8 | 35.3 | 37.2 | 40.1 | 46.1 | 50.6 | 54 | 53.7 | 49.1 | 43.5 | 38.3 | 35.7 |
| High | 46.4 | 49.6 | 53.7 | 58.9 | 64.1 | 69 | 75.8 | 76.7 | 70.4 | 59.5 | 51.1 | 45.8 |
Sammamish has fewer freezing nights than 23 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 Sammamish use?
5 official codes near Sammamish are verified; each links to its document.
| Place | Verified frost line | Distance |
|---|---|---|
| Redmond | 12 in | 7 mi away |
| King County | 12 in | 12 mi away |
| Lynnwood | 18 in | 20 mi away |
| Everett | 18 in | 27 mi away |
| Lake Stevens | 12 in | 28 mi away |
How likely is the soil in Sammamish to heave?
USDA rates the sampled soil around Sammamish as 100% none for frost action (main soils: Alderwood, Neilton, Beausite).
USDA NRCS soil survey, 9 sample points within 2 mi. Higher frost action means more risk of heave; see frost heave.
Sammamish at a glance
- Frost line depth
- No official local value
- County
- King County
- Population (2023 est.)
- 65,116
- Mean annual temperature
- 51.7 °F
- ZIP codes (3)
- 98029 · 98074 · 98075