Frost Line Depth in Portsmouth, Virginia
- 2 verified codes nearby
- Checked Oct 2026
No official local value
No official frost line depth is published for Portsmouth.
Nearby official codes require 12–18 in (2 verified codes).
Source and how we checked
We searched this place’s own code and website and found no published frost line depth.
Climate: 50 nights a year at or below 32 °F (NOAA 1991–2020, Norfolk S, 7.1 mi).
Checked Oct 2026. Report a correction
Does Portsmouth have an official frost line depth?
No adopted frost line depth found for Portsmouth 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 Portsmouth’s own number.
What frost line depth does Portsmouth use for footings under Table R301.2(1)? Is it 12 in, like Hampton?
How deep do footings, decks and water lines need to be in Portsmouth?
Drawn with the deepest nearby official value (18 in). Confirm Portsmouth’s own depth before you dig.
House or garage footing in Portsmouth: 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 Portsmouth?
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Portsmouth never averages a low below freezing. 50 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 32.2 °F.
NOAA 1991–2020 climate normals, Norfolk S station, 7.1 mi away, elevation 10 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 32.2 | 34 | 39.8 | 48.8 | 57.5 | 66.3 | 71.1 | 69.5 | 64.5 | 53.4 | 42.6 | 36 |
| High | 48.8 | 51.9 | 58.3 | 69.5 | 76.5 | 83.9 | 88 | 85.8 | 79.7 | 70.5 | 60.1 | 52.7 |
Portsmouth has fewer freezing nights than 21 of the 22 other Virginia places we track. The Virginia median is 94. Coldest: Shenandoah County; mildest: Norfolk.
What frost line depth do towns near Portsmouth use?
2 official codes near Portsmouth are verified; each links to its document.
| Place | Verified frost line | Distance |
|---|---|---|
| Hampton | 12 in | 13 mi away |
| Henrico County | 18 in | 66 mi away |
How likely is the soil in Portsmouth to heave?
USDA rates the sampled soil around Portsmouth as 68% none, 32% low for frost action (main soils: State, Urban land, Tomotley).
USDA NRCS soil survey, 9 sample points within 2 mi. Higher frost action means more risk of heave; see frost heave.
Portsmouth at a glance
- Frost line depth
- No official local value
- County
- Portsmouth city
- Population (2023 est.)
- 96,793
- Mean annual temperature
- 60.1 °F
- ZIP codes (8)
- 23321 · 23701 · 23702 · 23703 · 23704 · 23707 · 23708 · 23709