Sinking Foundation Repair Olmos Park, TX.

Why Olmos Park foundations sink unevenly

What makes this pocket of Bexar County tricky isn't one bad soil, it's two very different ones side by side. Olmos Park straddles the escarpment where Blackland Prairie clay drops off into the dissected limestone of the Edwards Plateau, so a single lot can carry dense, moisture-hungry clay along one edge and near-surface bedrock along another.

That mismatch is a bearing problem. The clay here often runs a plasticity index of 40 to 60, fat clay, CH in the soil-classification tables, swelling through a wet spring, then shrinking hard through an August drought. The limestone next to it doesn't move at all, so one part of the slab rides up and down with the seasons while the neighboring part holds still.

The result is differential settlement: diagonal cracks off a window corner, a door that won't latch, a floor out of level room to room. It isn't the whole house dropping, it's two zones moving at different speeds and the frame tearing along the seam between them.

The active zone, and why depth matters here

Most shrink-swell trouble lives in the active zone, the upper eight to fifteen feet of soil that actually reacts to rainfall and drought. In the flat parts of San Antonio that zone is fairly uniform. Near the escarpment it's anything but.

Where limestone is shallow, the clay wedge over it might be only two to four feet thick. People assume a little clay over solid rock is harmless, it isn't. That thin layer still shrinks and swells with almost no capacity to spread a load evenly, so the house stays firmly supported where rock is near the surface while quietly losing support a few feet away, where the clay has dried and pulled down.

That's why a fixed "drive every pier to X feet" spec doesn't work here. Piers in the clay-heavy part of a yard travel much farther than piers already near rock, and the job has to handle both at once. Good foundation repair in Olmos Park is really about matching each pier to the ground beneath it.

How GroundLock lifts and stabilizes a sinking home

Signs it's time to get your Olmos Park home surveyed

Any one of these is worth a free look; two or more usually means movement is already underway:

• Diagonal cracks running at about 45 degrees from window or door corners, the classic clay-to-limestone differential signature near the escarpment.
• Interior doors or windows that stick or won't latch as the seasons swing from wet to dry.
• Floors that feel sloped or bouncy, or a gap opening between the floor and the baseboard.
• Exterior brick or mortar cracks that widen in summer and partly close after heavy rain.
• Separation where cabinets, counters, or trim meet the wall on one side of the house only.
• Water ponding against the foundation, or downspouts dumping right at the beam.

Olmos Park foundation repair questions