San Antonio, Texas
Foundation repair in San Antonio
San Antonio has the sharpest drought cycles of the four Texas metros we cover, and a good deal of the city sits on clay that responds to them dramatically. It also has a northern half sitting on dissolved limestone, where the problem is nothing like the same.
Two halves of one city
The Balcones Escarpment runs through San Antonio, and it divides the foundation picture almost as cleanly as it divides the landscape.
South and east of the escarpment is Blackland Prairie. Houston Black and Branyon clays, deep and highly expansive, doing what expansive clay does: taking on water and swelling through a wet spring, then contracting through a South Texas summer. The south side, east side, Converse, Kirby and the corridor toward Seguin are in this material. If you have a slab down here, seasonal shrink-swell is almost certainly the mechanism to understand.
North of the escarpment — the far north side, Stone Oak, Hill Country Village, Shavano Park, the edge toward Boerne — you are on Edwards limestone with thin soil over rock. Much less shrink-swell, but two different problems in its place. Where a slab bears partly on rock and partly on soil or fill, it moves differentially. And the Edwards here is karst: limestone that groundwater has dissolved into voids, fissures and solution channels over geological time.
The Edwards Aquifer recharge zone is karst terrain — that is how it recharges an aquifer. This is not a reason to be alarmed about a house in Stone Oak; the overwhelming majority sit on entirely competent rock. It is a reason why pier design on the north side should be based on what the drilling actually encountered rather than an assumed bearing depth, and why geotechnical input carries more weight up there than on a flat clay lot to the south.
Drought, and the watering problem San Antonio has more than anyone
Standard Texas advice for expansive clay is to keep perimeter soil moisture as steady as you can, which in practice means watering the foundation during dry spells. San Antonio is where that advice collides hardest with reality, because the city's water supply is the Edwards Aquifer and drought restrictions here are triggered by aquifer levels — meaning the restrictions arrive at precisely the moment the advice becomes most relevant.
The good news is that SAWS rules have historically separated the two activities. Landscape irrigation by sprinkler is restricted by drought stage and assigned watering day; foundation watering with a hand-held hose, soaker hose or drip line is typically allowed more broadly, often subject to time-of-day limits. Because stages shift with aquifer levels within a single season, check what is currently in force rather than what applied last year.
The technique matters as much as the permission. Slow and consistent beats heavy and occasional: the objective is to prevent the soil from going through a violent shrink-then-swell cycle, and dumping water on ground that has been dry for six weeks can cause heave of its own. A soaker hose set back a foot or two from the slab, run briefly and regularly, is the usual recommendation.
The historic core
King William, Lavaca, Monte Vista, Dignowity Hill and Alta Vista are largely pier and beam, much of it a century old. These houses sit on a wooden floor structure over a crawl space, and they were built to be adjustable — a house that has been shimmed and re-leveled a few times across a hundred years is behaving normally rather than failing.
What deserves attention in these neighborhoods is the crawl space: moisture, ventilation, rot in sill beams and joists, and piers that a previous owner's contractor replaced with something that was never meant to carry a house. A rotted sill beam is frequently the real expense in an old San Antonio home, not the leveling itself.
Several of these areas sit within designated local historic districts, which can add a review step for exterior work. Worth establishing before a crew is booked.
Newer construction on the north and west
San Antonio has grown quickly and much of that growth has gone north and west onto terrain that required grading before it could be built on. The familiar pattern follows: cut on one side, fill on the other, engineered pad, post-tension slab. Fill settles on its own timetable, and movement on a newer house out here is more often a fill-and-drainage story than a native-soil one.
On a newer home, two things are worth doing before anything else. Check whether the builder's structural warranty is still in force — many run ten years on the foundation. And get a hydrostatic plumbing test, because a leak under a slab causes foundation movement on its own and finding one changes both the repair plan and the question of who pays for it.
Permits and local review
The City of San Antonio requires a permit for foundation repair and underpinning through Development Services, typically supported by engineered documentation. If the property is in a local historic district, expect an additional review for work affecting the exterior. Outside the city limits, requirements depend on whether you are in Bexar, Comal or Guadalupe County.