Short answer: Not every foundation crack is a problem. Thin vertical cracks are often from concrete shrinkage or normal settling. This Old House calls horizontal cracks the most concerning, because they usually mean soil pressure is pushing on the wall. Cracks wider than about 1/4 inch, cracks that grow, and cracks with sticking doors or sloping floors are signs to call a structural engineer.
Quick diagnosis
| What you notice | Most likely cause | What to check | Call a pro? |
|---|---|---|---|
| Thin vertical crack | Concrete shrinkage or settling | Mark and watch; seal if it leaks | Usually not |
| Diagonal crack, wider at one end | Uneven settling | Check doors and windows | If it grows |
| Horizontal crack in a block or poured wall | Soil or water pressure | Look for bowing | Yes |
| Stairstep crack in block | Settling or pressure | Measure width | Yes |
| Crack wider than 1/4 inch | Structural movement | Photograph with a ruler | Yes |
| Crack that leaks water | Water entry through a crack | Check grading and gutters | Often |
Why horizontal cracks matter
InspectAPedia and This Old House both describe horizontal cracks as a sign of lateral pressure from soil, water or frost against the wall. If the wall is also bowing inward, have an engineer look at it soon.
Monitor a crack
- Draw a pencil line across each end of the crack and write the date.
- Photograph it with a ruler or coin for scale.
- Check monthly. New cracks and growing cracks are not normal, according to This Old House.
Reduce water pressure on the foundation
- Keep gutters clean and downspouts extended away from the house.
- Grade soil so it slopes away from the foundation.
- Seal small, stable cracks to stop water entry.
When to call a professional
- Any horizontal crack, or a wall that bows or leans.
- A crack wider than about 1/4 inch, or one that grows.
- Cracks plus sticking doors, sloping floors or gaps at windows.
- Water keeps coming through the crack.
What it usually costs
This Old House reports foundation repair averaging about $5,179, with a typical range of $2,224 to $8,134. A structural engineer evaluation is separate and usually far less than repair.
Frequently asked questions
Are vertical foundation cracks normal?
Thin vertical cracks are common and often from shrinkage or settling. Watch them for growth and seal them if they leak.
Should I get an engineer or a foundation repair company?
An independent structural engineer can tell you whether repair is needed before a company quotes the work.
Related problems
Sources
- This Old House: Foundation cracks, what is normal and when to worry
- This Old House: Foundation settling vs. foundation problems
- InspectAPedia: Horizontal foundation cracks
This guide is general information, not a substitute for an inspection by a licensed professional. See our disclaimer.