Foundation Cracks in Clay Soil: Causes and Fixes

Much of Texas, and parts of Oklahoma, Colorado and the Southeast, sit on expansive clay. It swells with water and shrinks in drought. That constant movement pushes and pulls on foundations, which is why foundation repair is so common in these areas.

Normal cracks vs warning signs

Usually normal

• Thin hairline cracks in a slab or garage floor from concrete curing.
• Small cracks in drywall corners that do not grow.

Worth a closer look

• Stair step cracks in brick walls.
• Cracks wider than about a quarter inch, or one side higher than the other.
• Doors and windows that suddenly stick or will not latch.
• Gaps between walls and ceilings, or floors that slope.
• Cracks that grow over weeks or months. Mark the ends with a pencil and date them to track it.

Prevention: keep the soil moisture steady

• In drought, water the soil around the foundation evenly. A soaker hose a foot or two from the slab, run on a schedule, helps stop the clay from shrinking away.
• In wet weather, move water away: gutters, downspout extensions and soil sloped away from the house.
• Watch trees. Large trees close to the house pull a lot of water from the soil. Ask an arborist about root barriers.
• Fix plumbing leaks under or near the slab quickly; they can swell the soil in one spot.

Common repair methods

• Piers: concrete or steel piers driven or drilled down to stable soil, then used to lift and support the foundation. The most common fix for slabs in clay.
• Mudjacking or foam leveling: fills voids and lifts sunken slabs like driveways and patios.
• Drainage fixes: often part of any lasting repair.

Get the right inspection

For real movement, ask for an evaluation by an independent structural engineer as well as repair company quotes. The engineer has nothing to sell and can tell you what is actually needed.

Frequently asked questions

Does foundation repair come with a warranty?

Many companies offer long term or transferable warranties on piers. Read what is covered, especially if you may sell the house.

Is foundation movement covered by insurance?

Usually not when it is caused by soil movement. Damage from a sudden plumbing leak may be treated differently. Ask your agent.

Post your foundation job with photos of the cracks and get bids from local pros.