Troubleshooting

9 Common Stucco Problems (and How to Fix Them)

March 4, 2026 SD Plastering Team

Stucco is durable, but it's not indestructible — and almost every problem it develops falls into one of nine categories we see over and over across San Diego County. The key to keeping a small problem small is knowing what's causing it, because the wrong fix (painting over an active leak, patching a crack that's still moving) makes the underlying issue worse. Here are the nine, what causes each, and the right fix.

1. Hairline cracking

Cause: Normal curing, wood-frame settlement, and San Diego's seismic ground movement.

Fix: Cracks under 1/16 inch are cosmetic. Clean out the crack, fill with a color-matched elastomeric sealant, and blend the texture. Wider or growing cracks need a licensed contractor — the lath or framing is the problem, not the surface.

2. Staining (brown or rust streaks)

Cause: Water entering behind the stucco and leaching rust from the galvanized lath or tar from the Grade D paper.

Fix: The streaks are a symptom. Find and fix the water entry point (failed caulking, crack, or flashing gap) first, then clean and seal the stained surface. Covering the stain without stopping the leak guarantees it returns.

3. Efflorescence (white mineral deposits)

Cause: Water traveling through the wall dissolving salts, then depositing them on the surface as it evaporates.

Fix: A little after heavy rain is normal. Recurring or heavy efflorescence means there's a steady moisture source behind the wall — find and stop it. Light deposits brush off; persistent ones need the water source addressed or they'll keep returning.

4. Blistering or bubbling

Cause: Moisture trapped behind the finish coat pushes it outward as vapor. Usually a failed weather barrier or water entry at a penetration.

Fix: This is an active moisture problem, not a surface one. The blistered section must be opened, the substrate inspected and dried, the barrier repaired, and the section re-lathed and re-coated. Painting over blisters traps more moisture.

5. Impact damage (holes and chips)

Cause: Physical impact — landscaping equipment, vehicles, hail, or a stray baseball.

Fix: Small chips can be patched with a color- and texture-matched stucco mix. Larger holes that expose the lath need a proper three-coat patch (scratch, brown, finish) tied into the surrounding lath. Match the texture in raking light to hide the seam.

6. Soft or spongy spots

Cause: Advanced moisture damage — the substrate, paper barrier, or sheathing behind the stucco has rotted.

Fix: By the time stucco feels soft, the damage behind it is significant. Open the area, inspect and replace rotted substrate and paper, re-lath, and apply a three-coat patch. This is a repair you schedule this week, not next season.

7. Cracks at windows and doors

Cause: Concentrated structural stress at openings, plus failed caulking letting water in at the corners.

Fix: Re-caulk the perimeter with a high-quality elastomeric sealant, repair the crack with a color-matched patch, and verify the flashing above the opening is sound. If cracks return, the framing has moved and a contractor should inspect.

8. Fading or chalky surface

Cause: Years of UV exposure breaking down the cement paste or acrylic topcoat at the surface.

Fix: A chalky surface is early-stage erosion. A re-skim or a new elastomeric/acrylic recoat restores the finish and protects the wall. On painted stucco, a fresh coat of elastomeric paint bridges hairline cracks and extends surface life.

9. Bulging or separation from the wall

Cause: The stucco has detached from the lath — the most serious common problem. Usually moisture or lath failure.

Fix: Tap the wall: a hollow sound means the section has separated and is hanging by the lath. Stop walking under it, call a licensed contractor immediately, and plan to remove and rebuild that section. Left alone, it breaks off in chunks.

When to call a professional

Surface-level problems — a small chip, a hairline crack, fading — are fair game for a handy homeowner with the right materials. But anything involving water behind the wall, a soft or hollow section, a crack that's growing, or staining that keeps returning needs a licensed C-35 stucco contractor. The problem is almost always bigger than it looks, and the repair has to address what's behind the stucco — not just what's on top of it. SD Plastering Company has been diagnosing and fixing every problem on this list across San Diego County since 1984. We hold CSLB #915601, carry full insurance, and offer free on-site inspections. If you're unsure whether a problem is cosmetic or structural, request a free estimate or call (619) 599-3943.

Frequently Asked Questions

Are hairline cracks in stucco normal?

Yes. Cracks under 1/16 inch wide are normal as stucco cures and as a wood-framed home settles, especially in seismically active San Diego. They can be sealed with a color-matched elastomeric sealant. Cracks wider than 1/16 inch, cracks that run diagonally in a straight line, or cracks that widen over time indicate a structural or moisture problem and need a licensed contractor.

What does white powder on stucco mean?

White powder is efflorescence — mineral salts that water carries out of the stucco or masonry as it evaporates. A little after heavy rain is normal. Heavy or recurring efflorescence means water is traveling through the wall regularly, and the moisture source behind the wall should be found and stopped.

When is stucco damage an emergency?

Bulging, sagging, or a section that sounds hollow when tapped means the stucco has separated from the lath and can break off in chunks — keep people away from the area and call a licensed contractor immediately. Soft or spongy spots indicate advanced moisture damage and should be repaired within days, not months.