Sinking Foundation in Lubbock, TX

Why foundations sink in Lubbock

Clay that shrinks. USDA soil surveys show that common soils around Lubbock have a sandy or loamy top layer over a subsoil with more clay. Clay shrinks as it dries. When the soil under one corner dries out more than the rest, that corner loses support and drops.

Water in the wrong place. A corner can also sink when soil there stays soaked and soft. A gutter that dumps at one spot, a yard that slopes toward the house, a leaking sprinkler valve or a plumbing leak can all keep one area wet. Uneven water is the most common thread.

Rain in bursts. Lubbock averages about 18.6 inches of rain a year, according to the National Weather Service, and much of it falls in heavy storms after long dry stretches. The soil swings from dry to soaked and back, and a weak corner gets worse each cycle.

Low ground and filled playas. Lubbock drains to playa lakes. USDA says playa floor soil is 50 to 60 percent clay and cracks up to 40 inches deep when it dries. A 1999 Texas House bill analysis notes that filling playas during building caused flooding problems in parts of Lubbock. A house on or next to that kind of ground can sink more than its neighbors.

Caliche below. Many local soils turn into caliche, a hard layer packed with lime, roughly 2.5 to 5 feet down, according to USDA. The house usually sits on the moving clay above it. That matters for repair, because the crew has to reach firmer ground below the part that moves.

How a sinking foundation is fixed

The inspector takes floor level readings across the whole house to find the low area and how far it dropped. The plan should show where each support goes and why.

Pressed concrete piers. Short concrete cylinders are pushed into the ground under the low section, one on top of another, until they stop. Then the house is lifted and shimmed. Often the lower-cost option.

Steel piers. Steel pipe is driven down in sections, often deeper than concrete piers. Crews use these when firm ground sits deeper or the load is heavy.

Slab jacking. For a sunken porch, patio or garage slab section, material is pumped under it to lift it. This is for flatwork, not for the house itself.

Fix the cause. Piers hold the low corner up. Gutters, grading and leaks still need to be fixed, or another part of the house can start to sink.

After the lift, cracks often close part of the way. Brick and drywall usually still need patching. A city permit may be needed. The City of Lubbock says work that changes a home's structure needs one.

Before the inspection

1. Find the low corner. Use a marble or a phone level app in rooms near it.
2. Photo the cracks inside and out, with a coin for scale and a date.
3. Check your water bill for any jump in the last few months.
4. Watch the gutters in the next rain and see where the water goes.
5. Write down any past repairs or pier work on the house.