Foundation repair · Medina County, TX
The ground under Rio Medina swells about fourteen times as much as the ground under Hondo, and both of them are Medina County.
Foundation risk in Medina County turns on the address more than it does anywhere else we work. USDA soil data puts the linear extensibility under Rio Medina at 15.8 percent, which is top tier expansive clay, the same company as Houston Black and Anhalt. The same measure reads 7.5 percent at Castroville, 7.2 percent at LaCoste and 1.1 percent at Hondo, Natalia and D'Hanis. One county, a fourteen fold difference between the two ends of it, and nothing you can see from the street that tells you which end a house is on. That is why the floor gets measured here before anything gets said about repair. Inspections are free, 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 Medina County
Why the soil answer changes from one Medina County town to the next
Medina County has no single kind of ground. USGS mapping for the county lists eighteen geologic units at the surface and not one of them covers more than a fifth of it. The Leona Formation covers about 20 percent, Uvalde Gravel about 12 percent, the Wilcox Group about 11 percent, Devils River Limestone about 10 percent, Edwards Limestone about 8 percent, the Escondido Formation about 8 percent, Carrizo Sand about 8 percent and Glen Rose Limestone about 6 percent, with Austin Chalk, the Midway Group, terrace deposits, Anacacho Limestone, Buda Limestone and Del Rio Clay, Pecan Gap Chalk, alluvium and a thin strip of Eagle Ford filling in the remainder. Hard Cretaceous limestone sits in the north, coastal plain sand and clay in the south, and Pleistocene gravel and river terrace through the middle. The USGS mapping for Medina County is published at https://mrdata.usgs.gov/geology/state/fips-unit.php?code=f48325 That patchwork is why the soil numbers here refuse to settle on one answer. Pull the USDA data under each town and the linear extensibility, which is the measure of how much ground changes volume between wet and dry, reads 15.8 percent at Rio Medina, 7.5 percent at Castroville, 7.2 percent at LaCoste, 2.8 percent at Mico, 1.4 percent at Devine and 1.1 percent at Hondo, Natalia and D'Hanis. The high end of that range is expansive clay of the worst kind, the same tier as the Houston Black and Anhalt that cause most of the slab trouble in San Antonio and along the escarpment. The low end barely moves at all. Both of them are Medina County. In a county where every lot behaves the same you can make a fair guess from the street. In this one the address decides the diagnosis, which is why a free inspection that measures the floor instead of assuming the soil buys you more here than it does anywhere else on our map.
Rio Medina and the heavy clay on the east side
The map unit under 78066 is 90 percent Monteola gravelly clay and it measures a linear extensibility of 15.8 percent, the highest number anywhere in this county and as high as clay gets in this region. Monteola is very deep, very slowly permeable, and it opens cracks 0.4 to 2 inches wide that reach 20 inches down or more when it dries. There is no shallow rock in the profile to stop any of that, so a slab rides the full seasonal column, perimeter beams drop through a dry summer, interiors dome, and piers keep going until they find load bearing strata rather than stopping on a shelf.
The Medina River bottom at Castroville
The map unit under 78009 is 80 percent Divot clay loam at a linear extensibility of 7.5 percent, moderate for this part of Texas, and the USDA classifies that unit as occasionally flooded. Two things are moving a house here instead of one. The clay swells and shrinks through the seasons, and the water that the river bottom holds softens bearing and finds the low corner of a slab. Grade, downspouts and where water stands after a storm matter as much on this ground as the clay number does.
The limestone terraces at LaCoste
The map unit under 78039 is 92 percent Knippa clay with small amounts of Montell and Castroville, and it measures 7.2 percent. Knippa is a dark calcareous clay over limestone on stream terraces below the hills, with vertic features through the upper 4 to 40 inches and a calcic horizon of cemented carbonate starting 18 to 40 inches down. Movement here is real but it is shallower than Rio Medina's, and the cemented layer changes what a pier meets on the way down, which is a thing to find by probing rather than by assuming.
Hondo, D'Hanis, Natalia, Devine and Mico, where the clay number collapses
Linear extensibility reads 1.1 percent at Hondo, D'Hanis and Natalia, 1.4 percent at Devine and 2.8 percent at Mico. That is ground that barely changes volume between wet and dry. Houses on this side of the county still go out of level, but the cause is usually something other than swelling soil, most often poorly compacted fill under part of the footprint, erosion that undercuts an edge, or a plumbing leak washing fines out from under a slab. Reading one of those as clay movement gets you a pier plan that does not fix the problem.
Straight from the soil survey
What the USDA maps under Medina County.
Two of the series in this table were described here. The USDA set the type location for the Divot series in Medina County, 6.3 miles south of US 90 at Hondo on Farm Road 462, and the type location for the Castroville series in Medina County as well, 3.3 miles north of US 90 on Texas 173 east of Hondo. The rest of the numbers come from the soil survey read map unit by map unit under the towns we serve, which is the only way to get a useful answer in a county this mixed. Watch the swell column. It runs from 15.8 percent down to 1.1 percent without leaving the county line.
| Soil series | Share of county | How much it swells | What that means for a foundation |
|---|---|---|---|
| Monteola | — | LEP ≈ 15.8% | Very deep, well drained, very slowly permeable clay with 40 to 60 percent clay in the control section, cracking 0.4 to 2 inches wide at the surface and reaching 20 inches down or more when dry. It makes up 90 percent of the map unit under Rio Medina. Very little of what we work on moves harder, and because the profile runs past 80 inches with no rock in it, the pier is looking for bearing well below the soil that is doing the moving. |
| Divot | — | LEP ≈ 7.5% | Deep calcareous alluvium on flood plains and flood plain steps, 35 to 55 percent clay, cracking 0.4 to 1 inch wide to a depth of 10 to 20 inches or more. It makes up 80 percent of the map unit under Castroville, and that unit carries an occasionally flooded classification, so swell and water have to be sorted out from each other before anyone decides what the repair is. Medina County is the type location for the series. |
| Knippa | — | LEP ≈ 7.2% | Dark calcareous clay on stream terraces below the limestone hills, 40 to 55 percent total clay, vertic features from 4 to 40 inches and a calcic horizon of cemented carbonate at 18 to 40 inches. It makes up 92 percent of the map unit under LaCoste. The seasonal movement is shallower than the heavy clay on the east side of the county, and the cemented layer is the reason depth to bearing on this ground gets probed rather than guessed. |
| Montell | — | Expansive and sodic. Fine, smectitic, hyperthermic Sodic Haplusterts, 40 to 60 percent total clay, cracks 0.4 to more than 2 inches wide that stay open 150 to 210 days in most years. | Only about 3 percent of the map unit under LaCoste, but worth naming because of how it behaves. Exchangeable sodium runs from 15 to more than 40 percent within the top 40 inches, which disperses the clay, and undisturbed Montell carries gilgai microrelief, so the lot can look lumpy before anything is ever built on it. Where it shows up, drainage work earns its keep. |
| Castroville | — | Low for clay country. Fine-silty, carbonatic, hyperthermic Typic Calciustolls, 25 to 35 percent silicate clay in the control section with total carbonates above 40 percent and rising with depth. | Named for the town and mapped as about 2 percent of the map unit under LaCoste, which is a useful reminder that a series name is not an address. It is well drained silty clay loam more than 80 inches thick, so the risks on this soil are bearing, erosion and drainage rather than swelling, and the repair plan looks nothing like the one written for Rio Medina. |
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 Medina County
The Medina 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
Pier and beam or slab, the ground still sets the repair here
Both construction types are in this county. Older houses tend to be pier and beam over a crawl space, and the stock built from the middle of the last century onward is mostly slab on grade, with post tension slabs in the newest subdivisions. That history matters less here than usual, because the same plan on the same day behaves differently depending on which end of the county it was poured on. A slab on the Rio Medina end sits over a deep column of clay that swells 15.8 percent, so it moves through the whole column with the seasons and the repair goes deep. A crawl space in the Medina River bottom at Castroville turns into a moisture, grade and drainage job at least as often as it turns into a pier job, because the ground there holds water and the map unit is classed occasionally flooded. At LaCoste the clay is over limestone with cemented carbonate inside 40 inches, so the movement tends to be shallower and the pier meets something firmer sooner. Out at Hondo and D'Hanis, where the soil barely swells, a house that is out of level is usually telling you about fill, erosion or a leak instead. Same county, four different first questions.
Permits in Medina County
Who signs off on a foundation repair here.
Whether a permit is involved depends on whether the address is inside a city or out in the unincorporated county, and we confirm that for the specific address before a crew is scheduled rather than assuming it. Inside city limits the city sets the rules, and a city can require a permit, an inspection or a contractor registration that the county does not ask for. Out in the unincorporated parts of Medina County the questions that come up on a foundation job are usually floodplain and work inside the right of way rather than a residential building code. Floodplain deserves its own look in this county. The Medina River bottom runs through the middle of the area we serve here, and the USDA classifies the map unit under Castroville as occasionally flooded, so a repair close to the river can pick up a review that the same repair on higher ground would never see. We make those calls ourselves and we get the answer in writing wherever the authority will put it in writing. The inspection that tells you which situation your address is in is free either way.
Costs, warranty and inspections
The straight numbers in Medina County.
Straight answers
Foundation questions people ask in Medina County.
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We'll call to schedule, usually within one business day. Prefer to talk now? (210) 816-0034.
- 60–90 minutes on site, including the elevation survey
- Written summary whether or not repair is needed
- No-pressure pricing with firm numbers, no same-day-only discounts