Foundation Cracks Getting Bigger: When to Worry

Cracks that are often cosmetic

• Thin, vertical hairline cracks in poured concrete walls.
• Cracks that have not changed in years.
• Small shrinkage cracks in a basement floor slab.

Cracks that need a professional look

• Cracks that are getting wider or longer.
• Horizontal cracks in a basement wall, or a wall that bows inward.
• Stair-step cracks in block or brick walls.
• Cracks where one side is offset from the other.
• Cracks that leak water.
• Cracks along with sticking doors, sloping floors or gaps around windows (sticking doors, sloping floors).

How to track a crack

1. Mark each end of the crack with a pencil line and the date.
2. Measure the width at its widest point (a crack-width card or ruler works).
3. Photograph it with a ruler or coin for scale.
4. Check again every month or two, and after heavy rain or freezes.

When to call a pro

Call if a crack is changing, horizontal, stair-stepped, offset or leaking. For an unbiased opinion, consider hiring a structural engineer ($230–$3,800) before getting repair quotes. Repairs range from crack sealing ($250–$800) to piers ($1,000–$3,000 each) or bowing wall repair ($4,000–$12,000), according to our foundation repair cost guide.