Foundation repair · Port San Antonio, TX
Foundation repair around Port San Antonio and the old Kelly Field, on ground that barely slopes.
Port San Antonio is the civilian half of what used to be Kelly Air Force Base, roughly 1,900 acres of hangars, shops and office buildings that went back to work after the base closed in 2001. The neighborhoods that grew up to house Kelly's workforce press right against the fence line. Houses and commercial slabs, one soil, one weather pattern, two very different sets of symptoms.
- Slab edges dropping on dead-flat lots
- Long cracks across bare commercial floors
- Mid-century houses deep into the cycle
- Water that stands instead of running off
The ground here is Branyon clay on slopes of 0 to 1 percent. It swells hard, it shrinks hard, and it has nowhere to drain. That combination is why we spend as much time on grading and downspouts in this ZIP as we do on piers, and why a wide flat floor slab has to be read differently from the house across the street.
AREAS WE SERVE AROUND PORT SAN ANTONIO: THE FORMER KELLY FIELD CAMPUS, THE THOMPSON NEIGHBORHOOD, THE RESIDENTIAL STREETS EAST OF THE AIRFIELD, AND THE US 90 FRONTAGE, A STRAIGHT RUN SOUTH ON LOOP 410 FROM OUR VANCE JACKSON SHOP.
What we see in Port San Antonio
The local patterns, specifically.
Slab edges dropping on dead-flat lots
With no fall across the lot, the perimeter is the only part of the clay that dries quickly. Drought pulls the exposed edges down while the middle of the slab stays supported, and the cracks open at door and window corners first.
Long cracks across bare commercial floors
A big slab holds moisture across more interior area and loses it along a much longer perimeter. The result shows up as a crack running across the floor rather than a stair step in brick, and how its width changes along its length is what tells us whether it is still working.
Mid-century houses deep into the cycle
The housing around the airfield went up in the 1940s, 1950s and 1960s. Those slabs have been through enough wet and dry swings that cracks are normal. The question worth answering is whether a given crack is finished or still ratcheting.
Water that stands instead of running off
Flat ground plus clay that seals when it wets means storm water sits against the foundation for hours. It is the finding we write up most often in this ZIP, and usually the cheapest item on the list to correct.
Straight from the soil survey
The USDA maps the dominant soil under Port San Antonio as Branyon, very high shrink–swell (linear extensibility ≈ 12%). Branyon is deep terrace clay with very high shrink and swell. Flat ground here carries both houses and large commercial slabs, and a wide slab on this soil has far more perimeter exposed to the wet-dry cycle than a house does.
See the Branyon soil series at USDA →The ground under the field
Port San Antonio sits on Branyon clay mapped at 0 to 1 percent slopes.
The USDA survey for 78226 is unusually tidy. A single map unit, Branyon clay, 0 to 1 percent slopes, covers the Port and the blocks around it, and Branyon is about 85 percent of what is in that unit. Houston Black and Lewisville make up the rest at roughly 5 percent each. Branyon is a deep terrace clay, and its linear extensibility is 12 percent, which is a measure of how far the ground changes in length as it takes on and gives up water. Twelve percent sits near the top of the range we work in, and it is why this ZIP carries a shrink-swell risk score of 90. The lab test behind that behavior is the plasticity index, and Central Texas clay covers how the same material behaves across the rest of the corridor.
The slope number is the part people skip, and out here it does half the damage. Zero to 1 percent means no fall. Water that lands on this ground does not leave, it soaks in, and Branyon seals as it wets so the rest of it puddles. Then the dry months arrive, the clay gives that water back from the edges inward, and the perimeter of every slab on the block loses support at the same time. On a sloped lot you can point water somewhere. Here, correcting drainage means building fall where none exists, which is a grading and extension job rather than a matter of cleaning out a swale. That is why drainage correction lands on so many of our write-ups in 78226 before piers enter the conversation at all.
Houses and commercial slabs on one soil
A wide flat slab does not move the way a house moves.
The Port campus and the light industrial buildings around it carry slabs several times the footprint of a house, and that changes the arithmetic. More interior area stays damp year round. More perimeter dries out each summer. The gap between the two gets wider than it ever gets under a three bedroom house, so movement reads as cracked and out of level floors inside the building instead of cracked brick outside it. Loading is rarely even either. Racking legs, equipment pads and truck aprons concentrate weight on spots the original slab design treated as uniform, and expansive clay responds to that difference.
We work both kinds of building out here. Motmot does light commercial foundation repair for offices, retail and mixed use, and we schedule it after hours and on weekends so a tenant does not have to close. The method does not change. We run the floor, put the numbers on paper, and scope the repair from the numbers. What changes is access, sequencing and how the work gets phased around people who are still using the space. How commercial foundation repair differs from homes walks through that in detail.
The neighborhoods the base built
Thompson and the streets east of the airfield went up with Kelly, and the slabs are that old.
Kelly Field has been flying since 1917, and the housing around it followed the payroll. Thompson, the neighborhood between US 90 and the Port, took its heaviest building in the 1940s, 1950s and 1960s, and it is named for Thompson Place, the street that runs through it. A good share of the families there worked at the base. The homes are modest minimal traditional and ranch houses, mostly brick and stone with some siding, on small flat lots, and they have ridden more wet and dry cycles than anyone has counted.
Age by itself is not the problem. A slab that has stayed level through six decades or more of this clay has earned some trust. What we look for is whether an old crack has stopped or is still opening a little wider each dry summer, and the floor elevation numbers answer that in one visit. When the numbers do call for support, the repair is steel piers or hybrid piers, both pressed to refusal on load bearing strata below the clay that moves with the weather. Piers run $600 to $1,000 each installed, so the count off the survey sets the price, and the pier work carries a lifetime transferable warranty that moves to the next owner. About a third of the inspections we run end with no repair needed, and those owners still leave with the measurements in writing.
Neighborhood by neighborhood
Port San Antonio foundation repair, street level.
Thompson
Small postwar houses on small flat lots, which is a combination that concentrates everything at the perimeter. Edge drop after a dry summer and water standing against the slab after a storm are the two findings that come up here again and again, and the second one causes a fair amount of the first. Short downspout extensions and a few inches of rebuilt grade do more good on these lots than most owners expect.
The Port San Antonio campus
Former Kelly hangars, shops and offices now leased to aerospace, defense, cybersecurity and advanced manufacturing tenants. Wide slabs on Branyon clay carrying loads the original pour never saw. Cracked and out of level floors inside a working building are a warehouse and shop floor problem, phased so the tenant keeps operating.
The streets east of the airfield
Residential blocks running back toward the Union Pacific tracks, built in the same postwar stretch as Thompson. Houses of that era in this part of town come both ways, slab on grade and raised floors, and the two read differently on a level, so we measure before anyone names a repair.
The US 90 frontage
Shops, service buildings and light industrial space along the highway, on the same flat clay as the houses behind them. Cracks running out of storefront window corners are the usual first complaint, and on a leased building the scheduling question matters as much as the scope.
Our work near Port San Antonio
Real foundation repair across Port San Antonio and the corridor.
Costs, warranty and inspections
The straight numbers on foundation repair in Port San Antonio.
Your nearest Motmot office
San Antonio (Main Office)
4402 Vance Jackson Rd Ste 206, San Antonio, TX 78230. Call or text (210) 816-0034.
Our main shop at Vance Jackson and Loop 410 runs the San Antonio metro daily and covers the I-35 corridor north to the Austin line.
Available in Port San Antonio
Our full service list, available across the corridor.
Port San Antonio specifics
Asked by Port San Antonio homeowners.
From the Learning Center
Reading for Port San Antonio homeowners.
Port San Antonio sits in Bexar County. The county page carries the USDA soil survey for the whole county, the series names and swell numbers, and how the ground changes from one side of it to the other.
Foundation repair across Bexar County →Nearby
Also serving the communities around Port San Antonio.
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