Foundation Crack Types Explained

Foundation crack types

Why horizontal cracks get taken more seriously

A vertical crack is usually the result of the concrete or masonry simply cracking under tension as it shrinks or settles slightly — generally a lower-severity event. A horizontal crack, on the other hand, typically indicates something actively pushing against the wall from outside — commonly expansive clay soil saturated with water, or hydrostatic pressure from a high water table — bending the wall inward. That bending mechanism is structurally more concerning than straightforward vertical settling cracking, which is why horizontal cracks are generally flagged for prompt professional evaluation rather than a wait-and-monitor approach.

Pro tip from our network contractors

Take dated photos of any foundation crack you're monitoring, including a ruler or coin in the shot for scale, and check back every few months. A crack that's stable over time is a very different situation from one that's visibly widening — and having that documented comparison makes any later conversation with a structural engineer much more useful.

When to call a structural engineer instead of a foundation repair contractor

For anything beyond a small, stable hairline crack, an independent structural engineer's assessment is worth the modest fee before committing to a repair — a company that sells foundation repairs has an inherent incentive to recommend one. See signs of foundation problems for the fuller picture of what else to check beyond cracks alone, and clogged gutters and foundation damage for one of the most common, fixable contributing causes.