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Bonham, Texas
Inside Bonham's city limits, shrink-swell clay limits houses without basements on 80% of mapped land, the 5th-highest of 11 cities in Fannin County. A shallow water table limits basements on 23%, the 2nd-highest of 11 cities in Fannin County.
That clay share is above Fannin County's 66%. FEMA's flood data list 17 flood losses since 2016 in ZIP code 75418 overlapping the city. Of its 3,457 homes, 60% were built before 1980; the median dates from 1975.
Data as of October 13, 2026 · sources · in Fannin 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 Bonham
Foundation repair in Bonham: shrink-swell clay limits slab homes on 80% of Bonham's mapped land, more than in 86% of Texas cities.
About 2,600 of Bonham's 3,457 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 Bonham city limits
| Expansive clay (limits slab homes) | 80.4% |
| High water table (limits basements) | 23.2% |
| Septic fields very limited | 91.6% |
| Clay swell (LEP, by area) | 7.4% |
| High-swell land (LEP 6%+) | 80.4% |
| Mapped soil | 6,193 acres |
What the numbers mean here
Clay swell averages a linear extensibility of 7.4% by land area here, and 80% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 80% of the mapped land.
Clay shrinks as it dries: 100% of Fannin County is in drought on the latest map, and 80% of Bonham's mapped land has shrink-swell clay.
On 23% of Bonham's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
USDA rates 92% of the land very limited for septic absorption fields.
Drought in Fannin County
100% of Fannin 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 Bonham. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 75418 | over 99% | 17 | $1.2 million |
Homes in Bonham
| Housing units | 3,457 |
| Median year built | 1975 |
| Built before 1980 | 60% |
| Built 2000 or later | 17% |
| Owner-occupied | 64% |
| Median value, owner-occupied | $201,800 |
| Single-family detached | 76% |
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