One Corner of the House Is Sinking, Now What

When one corner of the house drops and the rest stays put, you are looking at the most common settlement pattern in Central Texas, and the repair is smaller than most homeowners fear. Piers go under the affected run only, usually five or six of them wrapped around the low corner at $600 to $1,000 each, and the stable part of the house is left alone. Before any of that, make sure the corner is actually sinking, because the scariest-looking corner problem we get called about is usually a cosmetic one, and telling the two apart takes about a minute.

Rule out corner pop first

Corner pop is a chunk of concrete breaking off the outside corner of the slab, right where the brick sits on the foundation ledge. Brick expands and contracts with temperature, it drags the bonded edge of the concrete along with it, and eventually that corner spalls away. It looks dramatic and it is almost always cosmetic. Nothing under the house has moved. We cover what corner pop is and why it is usually cosmetic separately, including the patch that fixes it.

A sinking corner is a different problem in every way that matters. The concrete corner can look perfect while the evidence stacks up around it. Stair-step cracks climbing the brick toward that end of the house. Doors in the nearby rooms rubbing their frames. A floor you can feel leaning toward the outside wall. Corner pop is surface concrete flaking off a corner that has not moved. A sinking corner is a corner that has moved while its concrete stays whole. Keep those two straight and half the panic goes away.

Why corners move before anything else

Settlement rarely starts under the middle of a house. The clay beneath the protected center sits at a nearly constant dampness year round because the slab shields it from sun and rain. The perimeter takes the weather, and a corner takes it from two directions at once. Two exposed faces mean the soil at a corner dries fastest in a drought summer and wets fastest in a storm, so the clay there swings through bigger volume changes than any other soil under the house. That same restless ground also carries the ends of two intersecting walls. Our inspectors have measured the result for many years across San Antonio and Austin. When a slab foundation moves, a corner usually goes first, and it usually goes down late in a long dry stretch.

The three usual suspects at a low corner

When one corner is low and the other three behave, something local to that corner is driving the soil moisture. Three culprits cover most of the cases we diagnose.

The downspout. A gutter that discharges at the corner concentrates runoff from a big slice of the roof in one spot. Every storm saturates the clay there and every dry spell shrinks it back, and that hard wet-dry cycling works the corner loose over the years while the rest of the perimeter swings gently.

The tree. A mature live oak, elm, or hackberry within roughly twenty feet of the corner pulls a remarkable amount of water out of the ground in summer. The clay shrinks as the roots drink it dry and the corner follows the soil down. Tree-driven corners read worst in August and September, at the bottom of the seasonal cycle.

The clay pocket. Soil changes across a single lot. One corner of the footprint can sit over deeper or more expansive clay, or over fill placed when the pad was graded. Same weather, different soil, so that corner moves while the rest of the house holds still.

Naming the culprit matters, because piers do not fix a downspout. When runoff is doing the damage, the lasting answer often pairs underpinning with gutter and grading work, and we walk through that call in foundation repair vs drainage correction.

Confirm the corner is low before anyone quotes piers

Cracks suggest. Elevations decide. A floor elevation survey maps the slab in tenths of an inch, and a settled corner draws an unmistakable picture, readings that fall steadily from the body of the house toward that one corner. Our ICC-certified inspectors shoot the survey, photograph the crack pattern, check where every gutter discharges, and note what is planted near the low readings, so the movement and its likely cause land in the same report. The inspection is free, and about a third of the inspections we run end with no repair needed, because plenty of alarming corners measure inside normal seasonal range.

If what you are seeing is broader than one corner, a sticking door here and a drywall crack there, start with the full checklist of foundation warning signs and see how your house reads. If the thing you notice most is the floor itself, the slope side of diagnosis and repair is covered in foundation repair for uneven floors.

The repair covers the affected run, not the whole house

Foundation repair is scoped by affected footage, not by house size. Piers are placed at roughly six-foot spacing under the walls that actually moved, and a corner takes support down both intersecting walls, with the corner pier shared between them. A typical settled corner needs help along something like twelve feet of the back wall and twelve feet of the side wall, which pencils out to five or six piers. The full spacing and count logic, with worked examples, is in how many piers does a house need.

We install steel and hybrid piers only, driven to load-bearing strata below the active clay, so the corner ends up supported by ground the weather cannot reach. At $600 to $1,000 per pier, most single-corner repairs land in the $3,000 to $6,000 range, and the piers carry a lifetime transferable warranty. The rest of the foundation is left alone on purpose. Walls that have not moved gain nothing from piers beneath them, and every added pier is money spent fighting a problem the house does not have.

After the lift, we come back for a yearly performance follow-up inspection to confirm the corner is holding, and the downspout or tree that started the story gets its own fix so it does not start a second one.

What to do this week

Extend the downspout away from the corner today if there is one. A ten-dollar extension removes the biggest variable while you sort out the rest. Photograph the cracks with a coin for scale and date the photos, because a record of whether things are moving is worth more than any single measurement. Then get the corner measured. The elevation survey turns the question from how bad it looks into a number, and the number decides everything that follows. If the corner reads inside seasonal range, you monitor and keep the water managed. If it reads low, you will know the pier count and the price before anyone digs.