March 4, 2026 · 7 min read
Stucco cracks are the single most common reason a homeowner calls us. The good news: most cracks you see are cosmetic and harmless. The honest news: a few of them are early warnings of a real problem, and you should not paint over those.
Hairline cracks (the safe kind)
Tiny, spider-web cracks under the width of a credit card edge are normal in cement stucco. Cement shrinks slightly as it cures, and walls flex with temperature swings. These cracks are cosmetic. They do not let water in, they do not affect strength, and you do not need to do anything about them other than paint over them every 7–10 years if they bother you.
Cracks that matter
- Stair-step cracks following the diagonal pattern of CMU or brick joints behind the stucco — a sign of substrate movement.
- Diagonal cracks running from the corners of windows or doors — usually deflection at the opening or a missing control joint.
- Long horizontal cracks at floor lines on a multi-story wall — often a sign of framing shrinkage or a missing horizontal control joint.
- Cracks with rust or efflorescence stains bleeding out — water is getting behind the stucco and corroding the lath. This is the urgent one.
The two-minute test
Press a fingernail along the crack. If you can’t catch it, it’s cosmetic. If your nail catches and the crack is wider than a credit card, get an opinion.
Why patching without diagnosing is a waste of money
Most stucco “failures” are actually water failures — a missing kickout flashing, a failed window pan, a roof-to-wall transition done badly. If you patch the crack without fixing the leak, the crack comes back inside a year. Always diagnose first.
When to call us
If you’re seeing rust stains, soft stucco, bulging, or cracks wider than a credit card, give us a call — we’ll come look at it for free and tell you honestly whether it needs attention or not.
