Texas
Foundation repair in Texas
Texas has more foundation repair activity than any other state, and it is not because Texans build badly. It is because a great deal of the state is built on clay that changes size with the weather. This guide to foundation repair Texas homeowners can actually use covers what that means for your house, what repairs cost here, and what to check before you sign anything.
The soil, and why it matters more here
The dominant story in Texas foundations is expansive clay. Certain clay minerals — smectites, of which montmorillonite is the famous one — absorb water molecules between their crystal layers and physically expand. Dry them out and they contract again, often leaving visible fissures in bare ground. The technical measure is the plasticity index, and across the Texas Blackland Prairie it routinely runs in a range that engineers classify as highly expansive.
Houston Black clay is the state soil of Texas and the single biggest character in this story. It forms a belt running roughly from the Red River south through Dallas, Waco, east Austin and San Antonio — a strip of former tallgrass prairie that happens to contain most of the state's population. Houston has its own high-plasticity clays from the Beaumont Formation, with a shallow water table and measurable ground subsidence complicating things further.
The consequence is a seasonal cycle you can almost set a calendar by. Spring rain swells the clay and lifts the perimeter of a slab. A hot, dry Texas summer pulls moisture back out — helped along by tree roots and by the simple fact that the edges of a slab dry faster than the middle — and the perimeter drops. Repeat that for fifteen years, add a large live oak on one side and a downspout dumping water on another, and different parts of the house end up at different elevations. The cracks you see in the drywall are the structure reporting that difference.
Most Texas homeowners first notice foundation symptoms in late summer or early autumn. That is the low point of the moisture cycle: the clay has been shrinking for months, the perimeter has dropped as far as it is going to, and the doors that were fine in May suddenly will not latch. It does not mean the damage happened in August — it means August is when the seasonal movement is at its maximum.
What Texas houses are built on
Foundation type is largely a question of when the house was built, and it determines what the repair looks like.
Slab-on-grade dominates. Texas skipped the basement — the clay makes excavation expensive and the water table in much of the state makes it a bad idea — so the overwhelming majority of Texas homes sit on a concrete slab poured directly on prepared soil. From roughly the late 1970s onward, most of those slabs are post-tension: steel cables run through the concrete and were tightened after it cured, putting the slab in compression so it can span soft spots without cracking. Post-tension slabs are more resilient, and they are also the reason a contractor should never be coring through your slab without locating cables first.
Pier and beam foundation repair is a different discipline again, and it is what you need in the pre-war neighborhoods — East Dallas, the Houston Heights, central Austin, King William and Monte Vista in San Antonio. The house sits on a wooden structure supported by piers over a crawl space. It moves differently than a slab and, importantly, it is far easier and cheaper to adjust: re-shimming a pier and beam house is a fundamentally less invasive job than underpinning a slab.
Basements exist in Texas but are rare enough to be a novelty outside a few pockets. If you have one, the failure mode to know about is lateral pressure from wet clay pushing a wall inward, which is a different problem than settlement and gets a different fix.
Where we cover
We cover the four Texas metros with the heaviest foundation repair demand. They share the clay problem but not much else — the soil under west Austin has almost nothing in common with the soil under east Austin, and Houston's subsidence issue does not exist anywhere else in the state.