Key takeaways
- Vertical hairline cracks are usually cosmetic, and horizontal cracks are a red flag.
- Stair-step cracks follow mortar joints and signal movement.
- Measure and date a crack, then watch it.
Vertical cracks
Thin vertical cracks in a poured concrete wall are common and usually come from the concrete shrinking as it cures. They may leak, but they are rarely structural unless they widen.
Sealing them with injection keeps water out.
Horizontal and diagonal cracks
A horizontal crack in a basement or crawl space wall often means soil pressure is pushing the wall inward. It can bow over time. Diagonal cracks running from the corner of a window or door can show settlement.
These deserve a prompt inspection and a plan to brace the wall and relieve pressure.
Stair-step cracks
In block or brick, cracks follow the mortar joints in a staircase pattern. They show that one part of the foundation has moved relative to another.
Repair means stabilizing the footing or wall first, then repairing the masonry.
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Quick answers
Should I seal a crack myself?
Small hairline cracks can be sealed cosmetically, but cracks that move, leak badly or show a pattern should be inspected first.
How can I tell if a crack is growing?
Mark both ends with a pencil and date, measure the width or install a crack gauge, and recheck over weeks and seasons.
Ready to talk it through? Get a free estimate or call 615-209-7643.