Foundation repair · Kendall County County, TX
Comfort and Boerne both gave their names to USDA soil series in 1979, and the two of them sit at opposite ends of what Kendall County ground does to a house.
Foundation repair in Kendall County comes down to which side of the county a house sits on. Up on the plateau the soil is high in clay but only four to twenty inches deep over hard limestone, so the movement is shallow and a pier reaches refusal fast. Down in the Cibolo Creek, Balcones Creek and Guadalupe River corridors where most of the houses actually are, the soil runs forty to eighty inches or more with no rock in it at all, and a slab rides the whole seasonal shrink and swell column. Inspections are free either way, steel and hybrid piers run $600 to $1,000 each, and about a third of the inspections we run end with no repair needed.
The ground under Kendall County County
How much soil sits between your slab and the limestone
Kendall County sits on the southeastern edge of the Edwards Plateau, above and across the Balcones Fault Zone, and the rock at the surface is Lower Cretaceous. USGS mapping for the county shows the Trinity Group, specifically the Hammett Shale, Cow Creek Limestone, Hensell Sand and Glen Rose Limestone, plus the lower part of the Fort Terrett Formation of the Edwards Group. The Glen Rose Limestone is split into Upper and Lower Members and carries the upper and middle Trinity aquifers. In Bandera and Kendall counties the Edwards Limestone is mapped undivided with the overlying Georgetown Limestone. Faulting along the Balcones Fault Zone produced the uplift and the Balcones Escarpment, with displacement of as much as 1,200 to 1,600 feet between Austin and San Antonio. That is the reason this county is not one kind of ground. For a foundation the practical split is simple. The hills give you rock within two feet of the surface. The valleys give you forty to eighty inches or more of soil with no rock in the profile at all. Most of the county's housing sits in the second condition, along the Cibolo and Balcones Creek corridors where Boerne and Fair Oaks Ranch developed, not up on bare ridge caprock, which is why the deep clay story matters more here than the county's rocky reputation would suggest. The USGS geologic mapping for Kendall County is published at https://mrdata.usgs.gov/geology/state/fips-unit.php?code=f48259
Inches of soil sitting on hard limestone
Edwards and Upper Glen Rose rock with Comfort and Eckrant soils on top, high in clay but only four to twenty inches of it before hard limestone. What fails here is shallow. The slab moves seasonally in the top foot or two, cracking shows up at doors and corners with no deep settlement behind it, and a pier reaches refusal quickly, so the work is about bearing on rock and controlling the water that sheds off it rather than about reaching depth.
The Glen Rose stair steps on the hillsides
The stepped Glen Rose slopes carry shallow marly rocky soil over rock. What fails here is water and slope. Runoff off the steps gets under the house, benched cut and fill puts part of the footprint on rock and part on loose fill, and the differential shows up as the downhill corner walking away from the rest of the house. Drainage correction and french drains often do more good on this band than piers do.
Deep valley fill with no rock under it
The Guadalupe River, Cibolo Creek and Balcones Creek corridors carry deep, nearly level to gently sloping loamy and clayey soils on flood plains and stream terraces, with deep expansive Krum on the higher terrace treads. This is where most of the county's houses are. What fails here is the full soil column. Krum opens cracks 0.4 to 1.2 inches wide reaching 24 to 48 inches down when it dries out, so slabs dish and heave through the seasons, crawl spaces stay damp, and piers have to keep going because there is no shallow rock to stop on.
Straight from the soil survey
What the USDA maps under Kendall County County.
These are the series the USDA soil survey publishes at county granularity for Kendall County, and two of them were established right here. The Comfort series and the Boerne series were both set up in Kendall County, Texas in 1979, which makes this county their type locality, and they sit at opposite ends of the foundation risk range. Comfort carries 40 to 60 percent clay over indurated limestone at 10 to 20 inches. Boerne carries 12 to 23 percent total clay and runs more than 60 inches deep with no rock in the profile. Same county, same survey year, roughly three times the clay in one as the other.
| Soil series | Share of county | How much it swells | What that means for a foundation |
|---|---|---|---|
| Comfort | — | High clay in a thin layer. 40 to 60 percent clay in the particle-size control section and 55 to 75 percent in the Bt horizon, over rock at 10 to 20 inches. | A shallow but very high-clay mat resting straight on a dolomitic limestone shelf, so a slab gets seasonal movement in the top foot or two with no deep soil column underneath to cushion it and pier installations reach refusal quickly. |
| Eckrant | — | Expansive, confirmed in the taxonomic class. Clayey-skeletal, smectitic, thermic Lithic Haplustolls, 35 to 60 percent clay in the control section and A horizon. | Genuinely expansive clay sitting on indurated limestone at as little as four inches, the classic Hill Country condition where every bit of the movement happens in a shallow surface layer directly under the footing. |
| Krum | — | High and deep. Fine, smectitic, thermic Udertic Haplustolls, 40 to 60 percent clay, cracks 0.4 to 1.2 inches wide opening from the surface down to 24 to 48 inches when dry. | Deep expansive valley soil with a solum 40 to more than 80 inches thick and no rock near the surface, so a slab on a terrace tread rides a full seasonal shrink and swell column instead of a thin one. |
| Boerne | — | Low. Total clay only 12 to 23 percent, silicate clay 9 to 18 percent, well drained with moderately rapid to moderate permeability. | Fine sandy loam or loam more than 60 inches deep on flood plains and low stream terraces, so shrink and swell is minor here and the real risks shift to flooding, scour, drainage and deep soft soil with no shallow rock to bear on. |
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 Kendall County County
The Kendall 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
The year on the plans matters less here than the band you are in
Boerne is a 19th century German settlement and the county seat, so the historic core carries the oldest stock in the county, and pier-and-beam over limestone block and rubble piers is the era-typical construction there. Mid-century additions brought in ranch-style houses from the transition period, when slab-on-grade started displacing pier-and-beam across Texas. The dominant wave in Kendall County is the modern one, recent and large, and that stock is post-tension slab on grade in subdivisions. Fair Oaks Ranch is a planned golf and country club development of that modern era and is slab dominant rather than pier-and-beam. The part that decides how a house behaves here is which soil band it sits on, not the year on the plans. Older Boerne pier-and-beam sits in the valley on deep alluvium, which makes it a crawl space, moisture and drainage job more often than a pier job. Newer slab subdivisions on terrace ground sit on deep expansive clay and move through the whole column with the seasons. A slab up on the caprock is a different animal again, shallow movement over rock, and it gets a different repair plan.
Permits in Kendall County County
Who signs off on a foundation repair here.
Kendall County is the clearest permit picture anywhere in our service area, because the county puts it in writing. A verification letter from the Kendall County Engineer dated March 4, 2026 states that Kendall County has not adopted building codes for single family residential developments, and that the county does not regulate land use and has not adopted zoning regulations in the unincorporated areas. What the County Engineer's office does handle is 911 addressing, regulating the subdivision of property, floodplain management, and permitting of development activities, and permits are required for driveways and modifications to them and for any work within county maintained right of way. For a homeowner out in the unincorporated county, that means the underpinning itself is not moving through a county residential building permit. Floodplain is still a live question down in the creek bottoms, and anything touching a driveway or the county right of way is its own permit. Inside city limits the rules belong to the city, and a city can ask for things the county does not. We confirm what the city wants before we schedule the work rather than assuming it, and the inspection that tells you which of those situations you are in is free.
Costs, warranty and inspections
The straight numbers in Kendall County County.
Straight answers
Foundation questions people ask in Kendall County County.
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