Foundation Cracks: When to Worry and When Not To
Nearly every poured foundation cracks somewhere. Direction and movement tell you far more than length does.
Most foundations crack, and most of it is normal
Concrete shrinks as it cures. In a long poured wall that shrinkage has to go somewhere, and it typically shows up as narrow vertical cracks, often near corners or openings. These are extremely common and usually a water-management question rather than anything else.
Direction tells you more than size
Vertical and near-vertical cracks are the common shrinkage pattern. Diagonal cracks stepping away from a corner or an opening are worth a closer look. Horizontal cracks running along a wall are the ones that deserve attention soonest — a horizontal crack in a basement wall can indicate pressure against the wall from outside, which is a different category of problem than shrinkage.
Is it changing?
A stable crack and a growing crack are different situations even if they look identical today. Mark each end with a pencil and write the date, or put a piece of tape across it. If it hasn't moved in six months, that's useful information. If it's visibly widening, that's useful information too — and worth acting on sooner.
Water is usually the practical problem
For most homeowners the issue isn't structural — it's that water comes through the crack after heavy rain. Injection fills the crack through the full depth of the wall from the inside, sealing that path without excavating around the foundation. That's what it's for, and it's a much smaller job than digging.
When to get someone else involved
If a crack is horizontal, if a wall is visibly bowing, if cracks are widening quickly, or if you're seeing doors and windows going out of square upstairs, that's beyond what a sealing conversation should cover. A structural engineer assesses those questions — a concrete contractor shouldn't be the one telling you a foundation is sound.
Need this done?
Snell Concrete & Construction handles crack injection across Missouri, based in Fulton. Free on-site estimates, and a straight answer on what the job actually needs.
Related guides
Answers before you call.
Are hairline cracks in a foundation normal?
Narrow vertical cracks in poured walls are very common and usually the result of normal curing shrinkage. They still matter if water is coming through, but the crack existing isn't by itself a sign of trouble.
What does a horizontal foundation crack mean?
Horizontal cracks can indicate lateral pressure on the wall rather than curing shrinkage, and they warrant attention sooner than vertical ones. That's an assessment for a structural engineer, not something to judge from a photo.
Will sealing a crack stop water getting in?
For water coming through a crack in a poured wall, yes — that's what injection is for. If water is coming up through the floor or over the top of the footing, the water is taking a different path and injection won't address it.
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