Foundation repair · Guadalupe County County, TX
The soil series named for Seguin is one of the quietest grounds in Guadalupe County, and the Blackland clay up in the northwest is one of the worst.
Guadalupe County is not one foundation problem, it is two. The northwestern third sits on Cretaceous chalk and marl that weathers into 40 to 60 percent clay Vertisols the USDA rates very high for shrink-swell, and the southeastern half sits on deep Tertiary sand the same survey rates very low. Which half your house stands on changes the diagnosis, the repair, and often whether you need a repair at all. The inspection is free either way, and about a third of them end with no repair needed.
The ground under Guadalupe County County
What moves most and what barely moves in Guadalupe County
The Texas Blackland Prairie hands off to the Post Oak Savannah inside this county, and the geologic map is what draws that line. The published county map, compiled from the USGS state geologic map, shows sixteen units running oldest in the northwest to youngest in the southeast, from the Glen Rose and Edwards limestones through Eagle Ford, Austin Chalk, Buda Limestone, Pecan Gap Chalk and the Navarro Group, then the Midway and Wilcox groups, then Carrizo Sand, the Reklaw Formation, Queen City Sand and the Weches Formation, capped by the Willis and Leona groups, Pleistocene to Holocene terrace deposits, and Quaternary alluvium along the Guadalupe River, the San Marcos River and Cibolo Creek. The practical split is simple. The northwestern third, the Schertz, Cibolo, Marion and Santa Clara side, sits on Cretaceous chalk, marl and calcareous clay, and that weathers into the Houston Black, Heiden and Branyon clays that swell. The southeastern half, out toward Kingsbury, Leesville and the Gonzales County line, sits on the Tertiary sand belt of the Wilcox, Carrizo, Reklaw and Queen City, and that weathers into the Patilo and Arenosa sands that barely move at all. Between those two halves, through the middle and northeast of the county around Geronimo and Kingsbury, the map shows a faulted belt trending northeast to southwest that brings the older Cretaceous limestones and chalks back up to the surface in narrow strips. It is the same regional Balcones and Luling structural trend behind the oil and gas the map labels south of Seguin in the Wilcox, Buda, Austin Chalk and Eagle Ford. The map also flags the Leona Group, Carrizo Sand, Wilcox Group, Edwards and Glen Rose as aquifers. Add the river and creek bottoms, which are alluvium and neither chalk clay nor upland sand, and you get a county where the first useful question about a cracked house is not what is wrong with it but where in the county it stands.
The northwest shoulder, where the clay moves most
The Schertz, Cibolo, Marion and Santa Clara side of the county, sitting over Cretaceous chalk, marl and calcareous clay. This is Houston Black, Heiden and Branyon ground, 40 to 60 percent clay that the 1977 USDA survey rates high to very high for shrink-swell. Failure here is seasonal. Doors that stick in August free up in February, cracks open and close with the weather, and slabs move in the middle as well as around the edge. Piers on this ground have to reach well past the active clay, so depth matters more than pier count.
The claypan uplands through the middle
Broad upland ridges with narrow valleys and drainageways, the Crockett, Demona and Windthorst ground that covers about a third of the county. The surface is sandy or loamy and drains fine, so the lot looks like nothing to worry about, but the survey rates shrink-swell moderate to high in the lower layers. The movement starts below the topsoil, which is why these houses tend to crack later and more suddenly than the ones on open Blackland clay, and why a surface look at the yard tells you almost nothing.
The faulted strip in the northeast
Through the middle and northeast of the county, around Geronimo and Kingsbury, the geologic map shows a faulted belt trending northeast to southwest that lifts older Cretaceous limestone and chalk back to the surface in narrow strips. The practical effect is that the ground can change inside a single property and a house can straddle two behaviors at once. We shoot elevations across the whole floor here rather than assume the soil map applies evenly to the lot.
The Seguin terraces along the river
Out toward Kingsbury, Leesville and the Gonzales County line, the Wilcox, Carrizo, Reklaw and Queen City sands reach the surface and weather into the Patilo and Arenosa soils the survey rates very low for shrink-swell. Clay heave is rarely the answer on this ground. What shows up instead is settlement into poorly compacted fill, erosion under a corner, and plumbing leaks washing sand out from under a slab. Piering it before finding the real cause is money spent on the wrong problem.
The southeastern sand belt, where almost nothing moves
Quaternary alluvium along the Guadalupe River, the San Marcos River and Cibolo Creek, which is neither chalk clay nor upland sand. This is where the older pier-and-beam stock sits and where the Seguin and Sunev soils are mapped. Problems here are wet crawl spaces, rotted or crumbling perimeter beam supports, erosion and drainage rather than heave. It is also the ground where floodplain rules are most likely to touch the job.
Straight from the soil survey
What the USDA maps under Guadalupe County County.
These figures come from the 1977 USDA Soil Survey of Guadalupe County, Texas, which is the level at which soil in this state is actually published and the reason a county page can tell you something a city page cannot. The scanned survey is free to read at archive.org/details/usda-soil-survey-of-guadalupe-county-texas. Branyon is listed first because it is the most extensive named soil in the county, though the Crockett association covers the most total ground. Linear extensibility values were not published for these Guadalupe County series in a form we could verify against a primary source, so instead of guessing at a number the shrink-swell column carries the survey's own rating for the association each soil sits in.
| Soil series | Share of county | How much it swells | What that means for a foundation |
|---|---|---|---|
| Branyon | 45,614 acres of Branyon clay, 0 to 1 percent slopes, 9.9 percent of the county and the largest single map unit; about 52 percent of the Branyon-Barbarosa-Lewisville association, which covers about 23 percent of the county | High to very high (association rating, 1977 USDA survey) | A true Vertisol, classified Fine, smectitic, thermic Udic Haplusterts, 40 to 60 percent clay in the particle-size control section and very deep with solum greater than 203 cm or 80 inches, lying on broad smooth ancient terraces, so a slab on it rides up and down with soil moisture and interior movement is as common as movement at the perimeter. |
| Crockett | 31,280 acres of Crockett loam, 2 to 5 percent slopes, eroded, 6.8 percent of the county; about 40 percent of the Crockett-Demona-Windthorst association, which covers about 33 percent of the county and is the largest association by area | Moderate to high in the lower layers (association rating, 1977 USDA survey) | The classic claypan profile, a sandy or loamy surface sitting on a dense clay subsoil, so the ground reads harmless at the surface while the movement happens well below it and the owner gets no warning until a wall or a brick line cracks. |
| Houston Black | About 52 percent of the Houston Black-Heiden association, which covers about 22 percent of the county on rolling broad ridges, in valleys and on hills in the steeper areas; Heiden is about 29 percent of the same association | Very high, the strongest rating given to any association in the county (1977 USDA survey) | The Texas state soil and the hardest swelling ground in the county, classified Fine, smectitic, thermic Udic Haplusterts, 40 to 60 percent clay in the control section, very deep at greater than 203 cm or 80 inches, very slow permeability and moderately well drained, so cracks open through a dry summer and close again after a wet week. |
| Patilo and Arenosa | The Patilo-Arenosa association covers about 13 percent of the county on low hummocky hills and in narrow valleys, about 42 percent Patilo, 28 percent Arenosa and 30 percent Nebgen and Jedd | Very low (association rating, 1977 USDA survey) | Deep sand over the Carrizo and Queen City outcrop belt in the eastern and southeastern county that hardly swells at all, so a cracked slab standing on it is usually settlement, poor fill, erosion or a plumbing leak rather than clay heave, and it needs a different repair. |
| Seguin | About 20 percent of the Sunev-Seguin association, which covers about 7 percent of the county on smooth flood plains and terraces; Sunev is about 32 percent of it | Low to moderate (association rating, 1977 USDA survey) | Classified Fine-silty, carbonatic, thermic Fluventic Haplustolls with 18 to 30 percent silicate clay in the control section, well below the 40 to 60 percent of the county's Vertisols, deep, well drained and moderately permeable, so trouble on it is normally settlement, drainage or crawl space moisture rather than heave. |
| Austin, Eddy and Doss | The Austin-Eddy association covers about 2 percent of the county on broad smooth ridges with narrow valleys and drainageways, about 40 percent Austin, 19 percent Eddy and 41 percent Doss, Altoga and Houston Black | Low to high (association rating, 1977 USDA survey) | The only shallow-to-rock ground in a county where the soils are otherwise very deep, with a chalk C horizon at 24 to 40 inches under Austin, chalk or soft limestone at 12 to 20 inches under Doss and white platy chalk at 10 inches under Eddy, so piers reach refusal fast and the recurring problem is a house sitting partly on rock and partly on soil. The survey also flags severe limitations for septic absorption fields here because depth to chalk is shallow. |
Linear extensibility (LEP) is the USDA's measure of how much a soil changes volume between wet and dry. Higher numbers move houses.
Where we work in Guadalupe County County
The Guadalupe County County towns we cover.
Each one has its own page, because the ground changes inside this county and the local pattern is what matters when you are standing in the house.
What gets built here, and when
Three building eras in one county and how each one fails
Three eras, and each one fails a different way. The older core of Seguin still carries genuine nineteenth and early twentieth century pier-and-beam sitting on the Guadalupe River terraces where the Seguin and Sunev soils are mapped. That stock shows up as sloping floors, rotted or crumbling perimeter beam supports and wet crawl spaces, not slab heave, and the fix is usually leveling, beam and support work, and getting water away from the structure. Schertz grew off Interstate 35, Randolph Air Force Base and the outward push of San Antonio, so the overwhelming majority of its houses are post-1960 slab-on-grade, with a 1960s through 1980s band of conventionally reinforced slabs and a much larger post-1990 subdivision band stacked on top of it, all of it sitting on the swelling northwest clays. Cibolo is newer again and is close to all modern subdivision slab. Out in the unincorporated county the mix runs older farmsteads on pier-and-beam alongside newer slab houses on acreage, and those are frequently on sand or claypan rather than the Blackland clay people assume. The year-built detail town by town sits on the city pages, because the mix shifts hard from one city limit to the next. Steel and hybrid piers run $600 to $1,000 each here, and the piers carry a lifetime transferable warranty.
Permits in Guadalupe County County
Who signs off on a foundation repair here.
Foundation repair permitting here is a city matter, not a county matter, and the split is clean enough to say plainly. Seguin, Schertz and Cibolo are each incorporated and run their own development and building departments, so structural work inside those city limits goes through the city and what the city asks for is what governs the job. Guadalupe County's own permits page lists driveway permits, excavation permits, on-site sewage facility permits and 911 location addressing. It does not list residential building permits, which matches the general Texas pattern where cities carry the building-code authority and counties do not. The practical result is that the same pier job needing a city permit on a Cibolo cul-de-sac may need no building permit at all on unincorporated land a few miles out, though septic, driveway and floodplain permitting still run through the county, and parcels down in the river and creek bottoms are the ones where floodplain review is most likely to come into it. Requirements differ by city and they change, so we confirm what the city or the county wants before anything gets dug, as part of the free inspection. We are ICC-certified inspectors and not engineers, so if a city wants a sealed design for your job we tell you that up front.
Costs, warranty and inspections
The straight numbers in Guadalupe County County.
Straight answers
Foundation questions people ask in Guadalupe County County.
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