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Sunnyvale, Texas
Inside Sunnyvale's city limits, shrink-swell clay limits houses without basements on 78% of mapped land, the 2nd-highest of 24 cities in Dallas County. A shallow water table limits basements on 6%, the 5th-highest of 24 cities in Dallas County.
That clay share is above Dallas County's 51%. FEMA's flood data list 2 flood losses since 2016 in ZIP code 75182 overlapping the city. Of its 2,792 homes, 7% were built before 1980; the median dates from 2006.
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 1 overlapping ZIP
of homes built before 1980
Foundation repair in Sunnyvale
Foundation repair in Sunnyvale: shrink-swell clay limits slab homes on 78% of Sunnyvale's mapped land, more than in 84% of Texas cities.
About 2,600 of Sunnyvale's 2,792 homes are detached houses.
| 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 Sunnyvale city limits
| Expansive clay (limits slab homes) | 78.5% |
| High water table (limits basements) | 5.7% |
| Septic fields very limited | 84.3% |
| Clay swell (LEP, by area) | 11.8% |
| High-swell land (LEP 6%+) | 81.8% |
| Mapped soil | 10,757 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Heiden | 18% | 80% |
| Burleson | 15% | 84% |
| Houston Black | 15% | 91% |
| Trinity | 14% | n/a |
| Ferris | 11% | n/a |
| Branyon | 7% | 92% |
What the numbers mean here
Clay swell averages a linear extensibility of 11.8% by land area here, and 82% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 78% of the mapped land.
Clay shrinks as it dries: 100% of Dallas County is in drought on the latest map, and 78% of Sunnyvale's mapped land has shrink-swell clay.
USDA rates 84% 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 Sunnyvale. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 75182 | over 99% | 2 | $71,059 |
Homes in Sunnyvale
| Housing units | 2,792 |
| Median year built | 2006 |
| Built before 1980 | 7% |
| Built 2000 or later | 69% |
| Owner-occupied | 92% |
| Median value, owner-occupied | $565,300 |
| Single-family detached | 94% |
Nearby cities
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Mesquite | 3 mi | 74% | 3% |
| Heath | 7 mi | 82% | 3% |
| Balch Springs | 7 mi | 45% | 34% |
| Forney | 7 mi | 83% | 3% |
| Rowlett | 8 mi | 78% | under 1% |
| Garland | 9 mi | 59% | under 1% |
| Seagoville | 10 mi | 74% | 12% |
| McLendon-Chisholm | 10 mi | 81% | 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