How to inspect stucco cracks on your home
Not every stucco crack is the same problem. A quick inspection with the right approach tells you whether a crack is cosmetic shrinkage or a sign that water is getting behind the wall.
What you'll learn
- How to tell a hairline crack from a structural crack
- What crack width and pattern reveal about the cause
- How to check for water intrusion signs at a crack
- Which cracks to monitor and which require immediate attention
Step by step
- Walk the perimeter in good light Do your inspection in morning or late afternoon light that rakes across the wall at a low angle. This sidelight makes cracks visible that flat midday light hides. Walk within 3 feet of the wall and scan each section systematically.
- Measure crack width A hairline crack is thinner than a credit card edge. A crack wider than 1/8 inch that you can slide a coin into is a more serious problem. Note the width at the widest point and whether the crack is wider at one end than the other.
- Check crack pattern and location Diagonal cracks at 45 degrees from window and door corners suggest foundation or framing movement. Cracks that follow a grid pattern suggest lath issues below. Cracks that run horizontally at consistent heights may correspond to lath seams.
- Look for staining and efflorescence Trace the crack and look for brown or rust staining at or below it. White chalky deposits called efflorescence at or below a crack mean water has been passing through the stucco at that point. Either sign means the crack is active, not sealed.
- Tap-test the surrounding stucco Use your knuckle or a rubber mallet to tap the stucco in a grid around each crack. Sound stucco makes a dense thud. Stucco that sounds hollow has delaminated from the lath beneath and needs attention beyond just filling the crack.
If a crack shows staining, efflorescence, or the surrounding stucco sounds hollow, stop monitoring and call a stucco contractor. These signs mean water is already inside the wall system.
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Keep learning.
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