Montgomery County, Virginia
Shrink-swell clay limits houses without basements on 33% of Montgomery County's mapped land, a higher share than 83% of US counties and the 3rd highest of 133 Virginia counties. A shallow water table limits basements on 6%.
None of the county is in drought on the October 13, 2026 Drought Monitor map, after 22.2% a week earlier. FEMA's flood data list 38 flood losses here since 2016, 16% of them in buildings with basements. 39% of homes were built before 1980, against 50% nationally; the median home dates from 1986.
Data as of October 13, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, October 13, 2026
of homes built before 1980
Soil under Montgomery County
| Expansive clay (limits slab homes) | 33.0% |
| High water table (limits basements) | 6.0% |
| Septic fields very limited | 87.1% |
| Clay swell (LEP, by area) | 4.0% |
| High-swell land (LEP 6%+) | 15.1% |
| Urban land, not rated | 1.2% |
| Mapped soil | 256,000 acres |
How we count · survey areas VA121 (2025-09-08)
What the numbers mean here
Clay swell averages a linear extensibility of 4.0% by land area here, and 15% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 33% of the mapped land.
Rain over the 12 months to August 2026: 31.56 in, 11.00 in below the 1991-2020 average year of 42.56 in.
USDA rates 87% of the land very limited for septic absorption fields.
Drought
0% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 51 of the last 52 weeks; the most was 100% of its area, in 29 weeks, most recently on the July 21, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 67% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
38 flood losses since 2016, $2.2 million paid. The worst year was 2024, with 13. Foundations of the buildings, where recorded: 16% basements, 35% slabs, 29% crawl spaces, 19% elevated. Median water depth outside the building: 28 in.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 12 |
| 2019 | 0 |
| 2020 | 7 |
| 2021 | 2 |
| 2022 | 0 |
| 2023 | 1 |
| 2024 | 13 |
| 2025 | 3 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 42.56 in |
| 12 months to August 2026 | 31.56 in (-11.00) |
| 2025 | 36.44 in (-6.12) |
| Wettest year since 1895 | 2020: 61.18 in |
| Driest year since 1895 | 1930: 20.81 in |
| Days with 1 inch or more, normal at BLACKSBURG NWSO (2 mi away) | 9.3 |
Homes
| Housing units | 42,794 |
| Median year built | 1986 |
| Built before 1980 | 39% |
| Built 2000 or later | 29% |
| Owner-occupied | 55% |
| Median value, owner-occupied | $304,600 |
| Single-family detached | 54% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Radford city, VA | 10 mi | 19% | 5% |
| Roanoke County, VA | 15 mi | 4% | 2% |
| Floyd County, VA | 17 mi | 1% | 8% |
| Craig County, VA | 20 mi | 3% | 15% |
| Pulaski County, VA | 20 mi | 19% | 6% |
| Salem city, VA | 20 mi | under 1% | 3% |
| Giles County, VA | 20 mi | 10% | 4% |
| Roanoke city, VA | 25 mi | 1% | 1% |
Sources: USDA SSURGO (September 8, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status