The five-minute check
Before you price anything, answer these five questions about your crack. They are the same things a structural engineer looks at first, and they cost nothing.
1. Which direction does it run?
Vertical or near-vertical is the reassuring answer — that is how concrete relieves shrinkage tension. Diagonal from a window or door corner is a stress point, usually settling, worth watching. Horizontal is the one that matters: it means soil is pushing the wall inward, and it is structural regardless of width.
2. How wide is it?
Under 1/16 inch (a credit card edge) is hairline and almost always shrinkage. Up to 1/4 inch is worth sealing but rarely alarming on a vertical crack. Over 1/4 inch deserves an assessment whatever the direction.
3. Is it stair-stepped?
In block or brick walls, cracks follow mortar joints and zigzag. A stair-step pattern means the wall is moving — either settling differentially or being pushed. It is not simply old mortar.
4. Are the two faces still flush?
Run a finger across the crack. If one side sits proud of the other, the wall has displaced, not just cracked. That is active movement and the single clearest reason to stop reading and call an engineer.
5. Is it growing?
You cannot answer this today, which is exactly why you should start now: pencil-mark both ends, write today's date, measure the widest point. Re-check in three months. A crack that has not moved through a full season of weather is dormant.
What a foundation crack costs to fix
| Your crack | Typical cost | Approach | What’s going on |
|---|---|---|---|
| Vertical, hairline, dry, not growing | $0 | monitor | Concrete shrinkage. Mark it and move on |
| Vertical, under 1/4 in., some moisture | $350 – 900 | inject | Seal for water and radon control |
| Diagonal from a window or door corner | $350 – 1,200 | inject + watch | Stress point. Monitor for growth |
| Stair-step through block or brick | $800 – 6,000 | assess first | Movement or soil pressure |
| Horizontal across the wall | $2,500 – 15,000 | structural | Soil pressure. Engineer before quotes |
| Offset — one face sits proud | $5,000 – 30,000 | structural | Active movement. Engineer now |
Source: Ranges reflect the repair each pattern typically requires. Structural patterns carry wide ranges because scope is set by an engineer's findings, not by the crack's appearance. · Last reviewed July 30, 2026 · Reference data · How we compile these figures
Note the first row. A dry hairline vertical crack that is not growing costs nothing to address, and that is the correct answer for a large share of the cracks people find. Detailed pricing is in foundation crack repair cost.
How to monitor a crack properly
Monitoring is free and produces better evidence than any single inspection, because it captures change over time rather than a snapshot.
- Mark both ends with a pencil line perpendicular to the crack, and write today's date beside it.
- Measure the widest point. A feeler gauge is precise; a coin edge works. Write the number down.
- Photograph it with something for scale — a ruler or a coin — in the frame.
- Re-check monthly for a season. Foundations move most between the wettest and driest months, so a full cycle is the meaningful test.
For precision, a crack monitoring gauge costs $10 – $25 and shows displacement in both axes. If you may eventually make an insurance claim or negotiate on a home sale, dated photographs and measurements are worth considerably more than a recollection.
Why foundations crack in the first place
- Curing shrinkage. Concrete loses volume as it cures — roughly 1/16 inch per 10 feet. That tension has to go somewhere. Most homes show several of these, usually within the first few years.
- Settlement. The house compresses the soil beneath it. Normal in the first 2–3 years and self-limiting; a problem when it continues or happens unevenly.
- Expansive clay. Soils that swell wet and shrink dry cycle the foundation seasonally. Common through Texas, Oklahoma and the Gulf states.
- Hydrostatic pressure. Saturated soil pushes laterally against basement walls. This is the classic cause of horizontal cracking.
- Frost heave. Water freezing in soil expands and lifts. Northern climates, shallow footings.
- Tree roots and erosion. Large roots displace soil; a leaking gutter or downspout washes it away. Both create the uneven support that produces diagonal cracking.
When to call someone, and who
Call a structural engineer ($450 – $600) if any of these are true:
- The crack is horizontal, or stair-stepped through block.
- It is wider than 1/4 inch, or the faces are offset.
- It has grown measurably in under three months.
- Doors or windows have started sticking in multiple rooms, or floors slope.
Why an engineer rather than a free contractor inspection: the engineer sells only the assessment. Their report defines the scope, and three contractors then bid against the same document — which is the only way quotes become comparable. It also fairly often comes back smaller than the free inspection proposed.
Related: types of foundation cracks, hairline cracks, signs of foundation problems, cost calculator.