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Dallas, Texas
Inside Dallas' city limits, shrink-swell clay limits houses without basements on 37% of mapped land. A shallow water table limits basements on 5%.
That clay share is below Dallas County's 51%. FEMA's flood data list 342 flood losses since 2016 in the 48 ZIP codes overlapping the city. Of its 590,237 homes, 48% were built before 1980; the median dates from 1981.
Data as of September 22, 2026 · sources · in Dallas County
expansive clay: shrink-swell limits slab homes
high water table: limits basements
flood losses since 2016 in 48 overlapping ZIPs
of homes built before 1980
Soil under Dallas city limits
| Expansive clay (limits slab homes) | 37.5% |
| High water table (limits basements) | 5.4% |
| Septic fields very limited | 70.7% |
| Clay swell (LEP, by area) | 8.5% |
| High-swell land (LEP 6%+) | 35.8% |
| Urban land, not rated | 21.4% |
| Mapped soil | 245,396 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Houston Black | 8% | 91% |
| Austin | 8% | 93% |
| Trinity | 7% | n/a |
| Eddy | 6% | 0% |
| Stephen | 5% | n/a |
| Frio | 3% | n/a |
What the numbers mean here
Clay swell averages a linear extensibility of 8.5% by land area here, and 36% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 37% of the mapped land.
Clay shrinks as it dries: 100% of Dallas County is in drought on the latest map, and 37% of Dallas' mapped land has shrink-swell clay.
USDA rates 71% 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 September 22, 2026 map. County detail.
Flood losses by ZIP code
FEMA flood records since 2016 in the ZIP codes that overlap Dallas. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 75217 | 8% | 6 | $15,865 |
| 75241 | 7% | 3 | $37,919 |
| 75211 | 5% | 3 | $13,694 |
| 75216 | 4% | 1 | $1,202 |
| 75236 | 4% | 1 | $0 |
| 75253 | 4% | 15 | $749,207 |
| 75229 | 4% | 41 | $2.4 million |
| 75227 | 3% | 10 | $129,811 |
| 75220 | 3% | 9 | $305,121 |
| 75228 | 3% | 3 | $30,211 |
| 75212 | 3% | 2 | $31,583 |
| 75243 | 3% | 16 | $941,055 |
| 75215 | 2% | 0 | $0 |
| 75232 | 2% | 8 | $194,170 |
| 75214 | 2% | 12 | $317,572 |
| 75248 | 2% | 10 | $40,064 |
| 75230 | 2% | 26 | $1.6 million |
| 75218 | 2% | 6 | $225,661 |
| 75235 | 2% | 0 | $0 |
| 75237 | 2% | 0 | $0 |
| 75238 | 2% | 8 | $528,225 |
| 75247 | 2% | 0 | $0 |
| 75208 | 2% | 1 | $5,830 |
| 75224 | 2% | 5 | $57,595 |
| 75231 | 2% | 6 | $76,251 |
| 75249 | 2% | 0 | $0 |
| 75287 | 2% | 2 | $0 |
| 75252 | 2% | 14 | $189,443 |
| 75203 | 1% | 0 | $0 |
| 75206 | 1% | 14 | $704,811 |
| 75207 | 1% | 22 | $2.9 million |
| 75233 | 1% | 3 | $3,471 |
| 75240 | 1% | 22 | $292,038 |
| 75209 | 1% | 18 | $651,687 |
| 75223 | 1% | 0 | $0 |
| 75225 | 1% | 6 | $200,673 |
| 75204 | 1% | 5 | $272,199 |
| 75254 | 1% | 11 | $402,106 |
| 75210 | 1% | 0 | $0 |
| 75219 | 1% | 14 | $287,938 |
| 75244 | 1% | 9 | $499,659 |
| 75201 | under 1% | 0 | $0 |
| 75226 | under 1% | 4 | $70,533 |
| 75202 | under 1% | 0 | $0 |
| 75251 | under 1% | 0 | $0 |
| 75246 | under 1% | 6 | $212,633 |
| 75270 | 0% | 0 | $0 |
| 75390 | 0% | 0 | $0 |
Homes in Dallas
| Housing units | 590,237 |
| Median year built | 1981 |
| Built before 1980 | 48% |
| Built 2000 or later | 26% |
| Owner-occupied | 42% |
| Median value, owner-occupied | $320,700 |
| Single-family detached | 41% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Nearby cities
Sources: USDA SSURGO (August 5, 2026) · US Drought Monitor (September 22, 2026) · FEMA NFIP v3 (September 9, 2026) · Census ACS 2020-2024. Methods · Data status