Slab foundation repair

Settlement vs. heave

Settlement is when part of the foundation drops, often at the edges where soil dries out. Heave is when swelling clay pushes part of the slab up, often in the middle. They can look alike from inside the house, but they need different fixes. Piers address settlement. Heave is mostly a moisture problem. A good inspection tells the two apart.

Common repair methods

• Pressed concrete pilings. Stacked concrete cylinders are pressed into the ground with a hydraulic jack until they won't go any further, then the slab is lifted and shimmed. It's common in Texas and usually the most affordable option.
• Steel piers. Steel pipe is driven deeper, often to more stable soil or bedrock. It costs more but can reach depths concrete pilings can't.
• Drilled concrete piers. Holes are drilled, reinforced and filled with concrete, sometimes with a belled bottom. Engineers often specify them, and they're usually the most expensive.

The right method depends on your soil, the house and the budget. If two contractors recommend different methods, an independent engineer's opinion can settle it.

What to expect

• Exterior and interior work. Piers along the perimeter go in through small excavations. Interior piers may require breaking through the slab or tunneling.
• A plumbing test. Lifting a slab can stress pipes underneath. Many contractors recommend testing the plumbing before and after the lift. Ask.
• Cosmetic follow-up. Some cracks close after a lift and others need patching. Doors may need adjusting.
• A permit and final elevations. Ask for the permit and a copy of the before-and-after elevation readings for your records.