Stucco & exteriors
How can you tell if your stucco has water damage?
By Michael Ward, owner of MKW Homes Inc
By Michael Ward, owner of MKW Homes Inc · Updated August 2026
The short answer
Look for the same hairline cracks coming back after patching, dark streaks or staining below windows, paint that bubbles, and soft or hollow spots when you tap the wall. Those signs mean water is likely getting behind the stucco and working on the framing. The stucco is the symptom. The wet wood is the real problem.
What the warning signs actually mean
Four signs matter most. Hairline cracks that keep coming back after you fill them. Dark streaks or staining on the wall below windows. Paint that bubbles or flakes in patches. And soft or hollow spots you can hear when you tap the wall with your knuckles. One sign alone can be nothing. Two or three together, in the same spot, usually means water is getting in and sitting there.
The damage you cannot see is what matters
The stucco itself is cement, and water rarely destroys it. The trouble is what sits behind it: the wood framing, the sheathing, and the paper or wrap that is meant to shed water. When that barrier fails, water soaks the wood and it rots slowly, out of sight. By the time you see a stain or a soft spot, the wall behind it has often been wet a long time. That is why a hollow tap near a window worries us more than a crack.
Why patching over it hides the problem
The common mistake is treating stucco damage like a paint job. Someone fills the crack, repaints, and the wall looks fine for a season. Then the same crack returns in the same spot, because the water source was never found. Patching seals the symptom and buys the rot more time in the dark. If a crack keeps opening in one place, fix the cause before you close the wall.
What to ask before anyone patches it
Ask how they will find where the water gets in, not just how they will fill the crack. A good answer talks about windows, flashing, roof edges, and where stucco meets other materials. Ask whether they will check moisture behind the wall, with a meter or a small opening, before repairing. And ask what they will do if the framing turns out wet. If the only plan is patch and paint, keep looking.
The one thing to remember
If cracks keep coming back, or you see staining and soft spots below windows, the real problem is water reaching the wood behind the stucco. Do not just patch and paint. Find where the water gets in first, or you are paying to hide rot instead of stopping it.
Follow-up questionsAnswered.
Can I check stucco for water damage myself?
To a point. Tap the wall and listen for hollow spots, look under windows for staining, and watch whether cracks return after you fill them. You cannot see behind the wall, so treat those signs as a reason to get it opened and checked, not a final diagnosis.
Are all stucco cracks a sign of water damage?
No. Thin hairline cracks are common as a house settles and are often harmless. What worries us is a crack that keeps reopening in the same place, one with staining running from it, or one near a window or roofline where water has a way in.
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About the author
Michael Ward, owner of MKW Homes Inc
Michael is a Liverpool-trained builder with over 20 years in the trade, running one four-person crew across Pasadena and the San Gabriel Valley. California license CSLB #1074934, verifiable on the CSLB website. He writes these guides from what the work actually involves.
