Which foundation cracks are normal?

Hairline vertical cracks under about 1/8 inch, fine diagonal cracks that stay narrow along their whole length, shallow surface crazing, and any crack that has not moved in years with clean edges that still line up. These are shrinkage and settlement. Seal them to keep water and radon out, but they are not structural emergencies.

Which foundation cracks are serious?

Horizontal cracks in a basement wall are the most serious pattern — they mean soil and water pressure are pushing the wall inward. So are widening stair-step cracks in block or brick, any crack wider than about 1/4 inch or wider at one end than the other, displacement where one side sits proud of the other, and whole-house symptoms like sticking doors, sloping floors, or a chimney pulling away.

How do I monitor a foundation crack?

Mark both ends with a pencil, write the date on the wall, and record the width at the widest point — or fit a $10 two-plate crack monitor across it. Photograph it with a ruler in frame. Check monthly for at least six months so you cover one wet season and one freeze cycle. No movement means you can seal it; any widening means a structural evaluation.

Who should inspect a foundation crack?

For anything in the urgent list, hire a structural engineer before a foundation-repair contractor. An engineer charges a flat fee of $400–$1,000 for an inspection and written report, sells you no remedy, and tells you whether the movement is active. Use that report to price the same scope with two or three contractors.

What does foundation repair cost in 2026?

Structural engineer inspection and report: $400–$1,000. Epoxy or polyurethane crack injection: $400–$1,200 per crack. Regrading and drainage work: $600–$3,000. Interior drain tile with a sump system: $5,000–$15,000. Carbon-fiber straps or steel beams for a bowing wall: $500–$1,200 per brace. Piering: $1,200–$3,000 per pier, or $10,000–$40,000+ for a full job.

Foundation cracks: fix now or wait?

Almost every house has foundation cracks. Concrete shrinks as it cures, soil settles under the footings, and the result is a set of hairlines that will never do anything. A small share of cracks mean something else — that the wall is being pushed, that one part of the house is moving relative to another, or that water has found a path in. The difference is readable from the crack's shape, direction, and width, and it decides whether you are looking at a $15 tube of sealant or a five-figure structural job.

The cracks you can monitor

These are the ordinary ones. They are worth sealing to keep water and radon out, but they are not a structural emergency:

Hairline vertical cracks under about 1/8 inch, often running from a corner of a window or door — shrinkage as the concrete cured, usually in the first year or two.
Fine diagonal cracks that stay narrow along their whole length, common as a new house settles onto its footings.
Surface crazing — a shallow map of fine lines on a slab or wall face, cosmetic only.
Cracks that have not moved in years, with clean, unspalled edges that still line up on both sides.

The cracks that mean call someone now

Horizontal cracks in a basement wall. The most serious pattern there is. A horizontal crack means soil and water pressure are pushing the wall inward. Do not wait on this one.
Stair-step cracks in block or brick that are widening, especially with the courses displaced sideways.
Anything wider than about 1/4 inch, or a crack that is noticeably wider at one end than the other.
Displacement. Run a finger across the crack: if one side sits proud of the other, the two halves are moving independently.
The whole-house symptoms. Doors and windows that suddenly stick, sloping floors, gaps opening above door frames, a chimney pulling away from the wall. These say the movement has reached the structure above.
Water coming through a crack under any real pressure, or a crack that weeps every time it rains.

How to monitor a crack properly

"Wait and see" is a real answer, but only if you actually measure. Mark both ends of the crack with a pencil and write the date on the wall. Measure the width at the widest point and write that down too — or buy a $10 crack monitor, a two-plate gauge you screw across the crack that reads displacement directly. Photograph it with a ruler in frame. Then check monthly for at least six months, through one full wet season and one freeze cycle, because soil movement is seasonal.

A crack that has not moved through a wet spring and a hard freeze is a crack you can seal and stop thinking about. Any measurable widening, or any new crack appearing nearby, converts this from monitoring into a structural evaluation.

Fix the water before you fix the crack

Most foundation movement is a water problem wearing a concrete costume. Soil that swells when wet and shrinks when dry pushes and drops the footings; water pooling against the wall drives the lateral pressure that causes horizontal cracks. Before spending anything structural, deal with the cheap causes: extend downspouts six feet out, regrade so the soil falls away from the house, clear the gutters, and look hard at any paving that pitches water back toward the wall. Our guide to repairing or replacing a driveway covers how a slab that slopes the wrong way sends water at your foundation. If your basement is finished or you are planning to finish it, finished basement resale value covers why waterproofing has to come before drywall.

Who to call, and in what order

For anything in the urgent list, hire a structural engineer first, not a foundation-repair contractor. An engineer charges a flat fee for an inspection and a written report, sells you nothing, and tells you whether the movement is active. A repair company inspects for free and quotes its own remedy. Pay for the independent opinion before you accept a $30,000 recommendation — and use the engineer's report to price the same scope with two or three contractors.

What it costs in 2026

Structural engineer inspection and report: $400–$1,000.
Epoxy or polyurethane crack injection: $400–$1,200 per crack.
Regrading and downspout/drainage work: $600–$3,000.
Interior drain tile and sump system: $5,000–$15,000.
Carbon-fiber straps or steel I-beams for a bowing wall: $500–$1,200 per brace.
Piering or underpinning a settling foundation: $1,200–$3,000 per pier, $10,000–$40,000+ for a full job.

See our methodology for how we build these bands. The spread between the drainage fix and the piering job is exactly why the diagnosis comes first.

The bottom line

Narrow vertical and diagonal cracks that hold still are normal — seal them and move on. Horizontal cracks, stair-step cracks that widen, displacement, and sticking doors are active movement, and waiting makes them more expensive. If you are unsure which you have, mark and measure for six months, fix your drainage in the meantime, and get an engineer rather than a contractor to make the call.