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Calvert, Texas
Inside Calvert's city limits, shrink-swell clay limits houses without basements on 57% of mapped land, the 2nd-highest of 4 cities in Robertson County. A shallow water table limits basements on 22%, the 3rd-highest of 4 cities in Robertson County.
That clay share is above Robertson County's 31%. FEMA's flood data list no flood losses since 2016 in ZIP code 77837 overlapping the city. Of its 554 homes, 57% were built before 1980; the median dates from 1975.
Data as of October 13, 2026 · sources · in Robertson 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 Calvert
Foundation repair in Calvert: shrink-swell clay limits slab homes on 57% of Calvert's mapped land, more than in 63% of Texas cities.
About 400 of Calvert's 554 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 Calvert city limits
| Expansive clay (limits slab homes) | 57.0% |
| High water table (limits basements) | 21.8% |
| Septic fields very limited | 73.8% |
| Clay swell (LEP, by area) | 6.5% |
| High-swell land (LEP 6%+) | 60.5% |
| Mapped soil | 2,487 acres |
What the numbers mean here
Clay swell averages a linear extensibility of 6.5% by land area here, and 61% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 57% of the mapped land.
Clay shrinks as it dries: 100% of Robertson County is in drought on the latest map, and 57% of Calvert's mapped land has shrink-swell clay.
On 22% of Calvert's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
USDA rates 74% of the land very limited for septic absorption fields.
Drought in Robertson County
100% of Robertson 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 Calvert. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 77837 | 100% | 0 | $0 |
Homes in Calvert
| Housing units | 554 |
| Median year built | 1975 |
| Built before 1980 | 57% |
| Built 2000 or later | 18% |
| Owner-occupied | 63% |
| Median value, owner-occupied | $116,700 |
| Single-family detached | 71% |
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