Frost Line Depth in Manassas, Virginia
- 3 verified codes nearby
- Checked Oct 2026
No official local value
No official frost line depth is published for Manassas.
Nearby official codes require 18–24 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: 94 nights a year at or below 32 °F (NOAA 1991–2020, Manassas, 1.1 mi).
Checked Oct 2026. Report a correction
Does Manassas have an official frost line depth?
No adopted frost line depth found for Manassas in its official documents (checked Oct 2026). The nearest official values, from codes we verified, are 18 to 24 in. Use the deepest of them until the building department confirms Manassas’s own number.
What frost line depth does Manassas use for footings under Table R301.2(1)? Is it 24 in, like Fairfax County?
How deep do footings, decks and water lines need to be in Manassas?
Drawn with the deepest nearby official value (24 in). Confirm Manassas’s own depth before you dig.
House or garage footing in Manassas: 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 Manassas?
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Average lows are at or below freezing from Dec to Feb. 94 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 24.2 °F.
NOAA 1991–2020 climate normals, Manassas station, 1.1 mi away, elevation 245 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 24.2 | 25.8 | 32.4 | 43.1 | 53.6 | 63.5 | 68.6 | 66.5 | 58.3 | 45.6 | 35.3 | 28.7 |
| High | 42.4 | 45.5 | 53.8 | 65.9 | 74.2 | 83 | 87.5 | 85.4 | 78.2 | 67 | 56.4 | 46.5 |
Manassas has fewer freezing nights than 11 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 Manassas use?
3 official codes near Manassas are verified; each links to its document.
| Place | Verified frost line | Distance |
|---|---|---|
| Fairfax County | 24 in | 13 mi away |
| Alexandria | 24 in | 22 mi away |
| Spotsylvania County | 18 in | 40 mi away |
How likely is the soil in Manassas to heave?
USDA rates the sampled soil around Manassas as 56% moderate, 44% high for frost action (main soils: Manassas, Calverton, Reaville).
USDA NRCS soil survey, 9 sample points within 2 mi. Higher frost action means more risk of heave; see frost heave.
Manassas at a glance
- Frost line depth
- No official local value
- County
- Manassas city
- Population (2023 est.)
- 42,696
- Mean annual temperature
- 55.5 °F
- ZIP codes (1)
- 20110