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Duncanville, Texas
Inside Duncanville's city limits, shrink-swell clay limits houses without basements on 31% of mapped land. A shallow water table limits basements on under 1%.
That clay share is below Dallas County's 51%. FEMA's flood data list 16 flood losses since 2016 in the 2 ZIP codes overlapping the city. Of its 14,027 homes, 58% were built before 1980; the median dates from 1978.
Data as of October 13, 2026 · sources · in Dallas County
expansive clay: shrink-swell limits slab homes
high water table: limits basements
flood losses since 2016 in 2 overlapping ZIPs
of homes built before 1980
Foundation repair in Duncanville
Foundation repair in Duncanville: shrink-swell clay limits slab homes on 31% of Duncanville's mapped land.
The city requires a permit for the work.
About 10,300 of Duncanville's 14,027 homes are detached houses.
| City permit | Required. Duncanville lists foundation repairs among the projects for which a permit is required. (City of Duncanville, read October 2, 2026) |
| Who designs the repair | The ASCE Texas Section's repair guidelines say a Texas-licensed engineer should evaluate the foundation and design the repair (2022 guidelines) |
| Prices | Cost guide ranges compared |
Soil under Duncanville city limits
| Expansive clay (limits slab homes) | 31.1% |
| High water table (limits basements) | under 0.1% |
| Septic fields very limited | 85.5% |
| Clay swell (LEP, by area) | 4.4% |
| High-swell land (LEP 6%+) | 15.6% |
| Urban land, not rated | 7.2% |
| Mapped soil | 7,174 acres |
What the numbers mean here
Clay swell averages a linear extensibility of 4.4% by land area here, and 16% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 31% of the mapped land.
Clay shrinks as it dries: 100% of Dallas County is in drought on the latest map, and 31% of Duncanville's mapped land has shrink-swell clay.
USDA rates 86% of the land very limited for septic absorption fields.
Drought in Dallas County
100% of Dallas County is in drought (D1 or worse) on the October 13, 2026 map. County detail.
Flood losses by ZIP code
FEMA flood records since 2016 in the ZIP codes that overlap Duncanville. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 75137 | 53% | 13 | $220,295 |
| 75116 | 46% | 3 | $50,438 |
Homes in Duncanville
| Housing units | 14,027 |
| Median year built | 1978 |
| Built before 1980 | 58% |
| Built 2000 or later | 9% |
| Owner-occupied | 66% |
| Median value, owner-occupied | $255,500 |
| Single-family detached | 74% |
Nearby cities
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| DeSoto | 4 mi | 49% | under 1% |
| Cedar Hill | 5 mi | 37% | under 1% |
| Cockrell Hill | 7 mi | 5% | under 1% |
| Grand Prairie | 7 mi | 58% | 2% |
| Glenn Heights | 7 mi | 75% | under 1% |
| Ovilla | 7 mi | 56% | under 1% |
| Lancaster | 9 mi | 68% | under 1% |
| Oak Leaf | 10 mi | 77% | under 1% |
Sources: USDA SSURGO (August 5, 2026) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · Census ACS 2020-2024. Methods · Data status