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Denison, Texas
Inside Denison's city limits, shrink-swell clay limits houses without basements on 41% of mapped land. A shallow water table limits basements on 1%.
That clay share is below Grayson County's 60%. FEMA's flood data list 6 flood losses since 2016 in ZIP code 75020 overlapping the city. Of its 11,397 homes, 66% were built before 1980; the median dates from 1967.
Data as of October 13, 2026 · sources · in Grayson 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 Denison
Foundation repair in Denison: shrink-swell clay limits slab homes on 41% of Denison's mapped land.
About 8,500 of Denison's 11,397 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 Denison city limits
| Expansive clay (limits slab homes) | 40.6% |
| High water table (limits basements) | 0.9% |
| Septic fields very limited | 74.5% |
| Clay swell (LEP, by area) | 6.3% |
| High-swell land (LEP 6%+) | 40.4% |
| Urban land, not rated | 8.8% |
| Mapped soil | 18,907 acres |
What the numbers mean here
Clay swell averages a linear extensibility of 6.3% by land area here, and 40% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 41% of the mapped land.
Clay shrinks as it dries: 100% of Grayson County is in drought on the latest map, and 41% of Denison's mapped land has shrink-swell clay.
USDA rates 75% of the land very limited for septic absorption fields.
Drought in Grayson County
100% of Grayson 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 Denison. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 75020 | 90% | 6 | $552,384 |
Homes in Denison
| Housing units | 11,397 |
| Median year built | 1967 |
| Built before 1980 | 66% |
| Built 2000 or later | 19% |
| Owner-occupied | 59% |
| Median value, owner-occupied | $180,900 |
| Single-family detached | 75% |
Nearby cities
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