Foundation Cracks: When to Worry and Who to Call

Almost every house develops some foundation cracks as concrete cures and soil settles. The skill is telling cosmetic cracking apart from structural movement. Thin, vertical, or diagonal hairline cracks in poured concrete are common and usually cosmetic. The warning signs are horizontal cracks, stair-step cracks in block or brick, cracks wider than about a quarter-inch, cracks that are actively widening, and secondary symptoms like doors and windows that suddenly stick, sloping floors, or gaps opening between walls and ceilings.

These problems are driven by soil. Expansive clay soils swell when wet and shrink when dry, heaving and dropping the foundation through the seasons; poor drainage saturates the soil next to the footing; and drought or large nearby trees can pull moisture out and cause settlement. Because soil moves seasonally, many cracks appear after the spring thaw or after major storms shift the ground.

The right professional sequence usually starts with a licensed structural engineer for diagnosis. An engineer is vendor-neutral: they assess the structure, identify the cause, and write a repair specification without selling you the repair. You then hire a licensed foundation contractor to execute that spec — and you can compare bids against an objective document rather than each contractor’s self-diagnosis.

Repair cost scales with the cause. Sealing a minor non-structural crack might be around $2,000. Stabilizing a settling foundation with helical or push piers, or full underpinning of a failing footing, can reach $25,000 or more. The driver is whether you are sealing a symptom or correcting structural movement, so an accurate diagnosis directly controls cost.

Document everything. Photograph cracks with a coin or ruler for scale and re-photograph monthly; a crack that is stable over a year is far less urgent than one visibly growing. Pair any repair with drainage correction — gutters, downspout extensions, and grading water away from the foundation — because uncontrolled water at the footing is the root cause of most foundation failure.