HomeTexasGuadalupe CountySeguin
Seguin, Texas
Inside Seguin's city limits, shrink-swell clay limits houses without basements on 74% of mapped land, the 5th-highest of 8 cities in Guadalupe County. A shallow water table limits basements on 2%, the 2nd-highest of 8 cities in Guadalupe County.
That clay share is above Guadalupe County's 52%. FEMA's flood data list 22 flood losses since 2016 in ZIP code 78155 overlapping the city. Of its 13,397 homes, 39% were built before 1980; the median dates from 1990.
Data as of October 13, 2026 · sources · in Guadalupe 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 Seguin
Foundation repair in Seguin: shrink-swell clay limits slab homes on 74% of Seguin's mapped land, more than in 78% of Texas cities.
About 9,200 of Seguin's 13,397 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 Seguin city limits
| Expansive clay (limits slab homes) | 73.6% |
| High water table (limits basements) | 2.0% |
| Septic fields very limited | 85.1% |
| Clay swell (LEP, by area) | 9.1% |
| High-swell land (LEP 6%+) | 73.6% |
| Mapped soil | 25,732 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Branyon | 29% | 92% |
| Barbarosa | 23% | n/a |
| Crockett | 10% | 94% |
| Queeny | 6% | n/a |
| Lewisville | 5% | n/a |
| Houston Black | 4% | 91% |
What the numbers mean here
Clay swell averages a linear extensibility of 9.1% by land area here, and 74% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 74% of the mapped land.
Clay shrinks as it dries: 100% of Guadalupe County is in drought on the latest map, and 74% of Seguin's mapped land has shrink-swell clay.
USDA rates 85% of the land very limited for septic absorption fields.
Drought in Guadalupe County
100% of Guadalupe 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 Seguin. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 78155 | 99% | 22 | $478,533 |
Homes in Seguin
| Housing units | 13,397 |
| Median year built | 1990 |
| Built before 1980 | 39% |
| Built 2000 or later | 39% |
| Owner-occupied | 65% |
| Median value, owner-occupied | $249,400 |
| Single-family detached | 69% |
Nearby cities
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Kingsbury | 10 mi | 35% | 12% |
| Marion | 11 mi | 84% | under 1% |
| New Berlin | 11 mi | 69% | 1% |
| Santa Clara | 12 mi | 82% | under 1% |
| New Braunfels | 12 mi | 59% | under 1% |
| Staples | 15 mi | 83% | under 1% |
| Cibolo | 15 mi | 78% | under 1% |
| Schertz | 17 mi | 63% | under 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