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Frost data
Frost line depth in Virginia
The short answer
Virginia publishes no single statewide frost depth. Virginia runs a statewide building code but leaves the frost figure to localities, and the northern and Shenandoah jurisdictions that publish one use 24 inches. Footings have to bear below that depth, and a water service line has to sit at least six inches below it and at least twelve inches down, which in Virginia works out to a minimum of 12 inches. Source: Virginia DHCD â Virginia Uniform Statewide Building Code (USBC) overview.
Virginia is unusual in having a genuinely statewide building code, the Uniform Statewide Building Code, and still not publishing a statewide frost depth. The figure is completed locally. Fairfax County uses 24 inches in its typical deck details, and Shenandoah County publishes the same figure in its design information.
Twenty-four inches suits most of the state, and the exception is the same one every Appalachian state has: the mountain counties along the West Virginia line freeze deeper and earlier than the coastal plain. Mill Gap, in Highland County, reaches its median first freeze on 3 October, almost eight weeks before Norfolk.
Virginia has not amended the water service burial rule, so the model-code language applies and the local frost figure sets the floor. In the 24-inch jurisdictions, that is two feet.
By jurisdiction
What Virginia jurisdictions publish
With no statewide figure, these are the depths real building departments have published.
| Jurisdiction | Frost depth | Source |
|---|---|---|
| Shenandoah County, VA | 24 in | Shenandoah County Design Information â |
| Fairfax County, VA | 24 in | Fairfax County Typical Deck Details â |
These are the jurisdictions whose published figure we could read and verify, so it isn’t a complete list of Virginia building departments. Yours may differ, and yours is the one that governs your permit.
The weather behind the number
When it freezes in Virginia
NOAA 1991 to 2020 normals at representative stations across the state.
| Station | First 32°F | First 28°F | First 20°F | Last 32°F | Nights below 20°F |
|---|---|---|---|---|---|
| CHARLOTTESVILLE AP | November 1 | November 13 | December 17 | April 3 | 17 |
| NEWPORT NEWS INTL AP | November 9 | November 20 | December 26 | April 1 | 8.1 |
| NORFOLK INTL AP | November 23 | December 8 | January 11 | March 17 | 3.6 |
| RICHMOND INTL AP | November 4 | November 15 | December 19 | April 3 | 12 |
| ROANOKE RGNL AP | November 1 | November 12 | December 13 | April 3 | 14 |
| WALLOPS ISLAND FLIGHT FAC | November 11 | November 24 | December 28 | March 31 | 10 |
Dates are the median: half of years cross that threshold earlier, half later. “no normal” means NOAA publishes none for that station, which at a warm station means it does not reliably get that cold. Source: NOAA NCEI U.S. Climate Normals, 1991-2020, retrieved 2026-09-09.
Across all 125 Virginia stations with published normals, the median first 32°F night falls around October 28 and the median station records 24 nights a year below 20°F, which is the coldest threshold NOAA counts and a decent proxy for a hard freeze rather than a light frost. The state’s spread runs from MILL GAP, where the median first freeze is October 3, to NORFOLK NAS at November 26.
The median Virginia station crosses freezing around 28 October and logs about 24 nights a year below 20°F, a mild profile that hides an eight-week internal spread. The Blue Ridge and the Alleghenies behave like a northern state; Hampton Roads behaves like the Carolinas. Norfolk Naval Air Station, the state’s latest, does not reach its median first freeze until 26 November.
Water lines
Burial depth for a water service line in Virginia
No verified Virginia-specific amendment to the water-service burial depth was found; the baseline IRC P2603.5.1 rule applies (below the frost line and not less than 12 inches below grade).
Under the model rule that Virginia works from, a water service line goes Water service pipe shall be installed not less than 12 inches (305 mm) deep and not less than 6 inches (152 mm) below the frost line.
which puts the floor here at 12 inches. 2021 International Residential Code, Section P2603.5 (Freezing), ICC free code viewer. Your water utility may specify more for the portion of the service it owns, and the building department that issues the permit has the final say. The national picture is on how deep water lines are buried.
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Common questions
Virginia frost line questions
How deep is the frost line in Virginia?
Virginia’s statewide code leaves the number to localities. Fairfax County and Shenandoah County both publish 24 inches, which is a reasonable guide for northern Virginia and the Valley. Mountain counties along the West Virginia border run colder. Your local building department has the figure that governs your permit.
Virginia has a statewide building code, so why is there no statewide frost depth?
Because the Uniform Statewide Building Code adopts the model residential code, and that code’s climate table is designed to be completed by each jurisdiction from local data. A single statewide frost figure would have to serve both Highland County and Virginia Beach, which have very little in common in winter. Leaving the cell local is the code working as intended rather than a gap in it.
Next
Where to go from here
The frost depth is the digging number. It won’t tell you whether your pipes are at risk this winter, and the two pages that will are at what temperature pipes freeze and when pipes freeze where you live, both with a ZIP lookup. If a pipe has already split, burst pipe repair cost covers the repair and the water damage behind it, and what to do about a frozen pipe is the page to open first.
Other state pages: Minnesota, Iowa, Michigan, Ohio, Indiana, Illinois, Wisconsin, Missouri, and all fifty in the national table.
Where these numbers come from
The Virginia frost figure was researched against the body that publishes it, and it’s recorded with a confidence note of “” in our source ledger. Freeze dates are NOAA normals for stations in the state, picked by a fixed rule rather than by hand: first-order stations, spread west to east. The full method is on our methodology page.
- Freeze dates and cold-night counts: NOAA NCEI U.S. Climate Normals, 1991 to 2020, annual and seasonal by station. Retrieved 2026-09-09. Field definitions are in the by-variable readme.
- ZIP code locations: U.S. Census Bureau 2023 ZIP Code Tabulation Area gazetteer, matched to the nearest station by great-circle distance.
- Virginia DHCD â Virginia Uniform Statewide Building Code (USBC) overview The Virginia frost depth figure and basis.
- Shenandoah County, VA â Design Information (frost depth 24 in.) The Virginia frost depth figure and basis.
- Fairfax County, VA â Typical Deck Details (frost depth 24 in. minimum) The Virginia frost depth figure and basis.
- 2021 International Residential Code, Section P2603.5 (Freezing), ICC free code viewer The water service line burial rule.
The full method, including how we pick a station and what we do when there is not one close enough, is on our methodology page.
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