Stucco Water Damage: Signs, Causes and Repairs

Does Stucco Absorb Water?

Yes, a little. Cement stucco is porous: rain soaks into the surface and dries back out. That's normal and harmless on its own.

What protects the house is what's behind the stucco. On concrete block, the stucco bonds straight to the block, which handles moisture well. On a wood frame wall, the 2023 Florida Building Code calls for a water-resistive barrier behind the stucco (Section R703.7) and a weep screed at the bottom of the wall. The Stucco Manufacturers Association explains that the weep screed is where water that gets behind the stucco drains out. Water becomes a problem when it gets in faster than that system can carry it away, or gets past the barrier.

Signs of Water Behind Stucco

From the outside:

• Stains that run down from window corners, the ends of roof edges or light fixtures.
• Blistered or bubbling paint. Parex, a large stucco maker, says blistering of a stucco finish "is often caused by water that has gotten behind the finish."
• White, chalky deposits (efflorescence), left when water moves through the stucco and evaporates.
• Cracks that keep coming back, especially at the corners of windows and doors.
• Soft, crumbly or hollow-sounding spots when the wall is pressed or tapped.
• Stucco pulling away or bulging from the wall (delamination).

From the inside: stains, peeling paint or swollen trim near windows, and a damp smell in rooms along an outside wall.

Where Water Usually Gets In

Water rarely soaks straight through a sound stucco wall. It gets in at the edges and openings:

• Windows and doors. The code's flashing section (R703.4) requires windows and doors to be flashed into the water-resistive barrier. Where that flashing is missing, or the sealant joint between stucco and frame has failed, rain finds its way in.
• Roof-to-wall joints. Where a roof edge runs into a stucco wall, rain running off the roof needs flashing that turns it away from the wall.
• The bottom of the wall. A weep screed that's buried in soil or mulch, or caulked or painted shut, can't drain.
• Cracks. Parex notes that cracks wider than 1/32 inch "could present issues with moisture intrusion." Hairline cracks are mostly cosmetic.
• Penetrations. Hose bibs, lights, vents and cables through the wall each need a sealed joint.
• Sprinklers. A sprinkler head that soaks the same stretch of wall every day keeps it wet.

How Water Damage Is Found

The source comes first. Parex says that before damaged finish is repaired, "a root cause analysis is needed," and that if the cause isn't corrected, the blistering "may reoccur." Finding it usually means:

• looking at the wall in person, especially around windows, doors, roof edges and the base of the wall,
• checking the sealant joints, the weep screed and any flashing that shows,
• on frame walls, moisture testing at suspect spots, sometimes through small probe holes that are patched afterward.

How Stucco Water Damage Is Repaired

The repair depends on what's behind the stucco:

1. Stop the water. Reseal failed joints, clear or fix the weep screed, redirect sprinklers, or correct flashing at a window or roof edge.
2. Repair the surface. Where only the finish has blistered, Parex's procedure scrapes off the loose finish, repairs any damaged stucco beneath, and applies new finish matched in texture and color.
3. Open the wall where needed. On a frame wall with wet barrier, lath or sheathing, the stucco around the damage comes off, the damaged layers are replaced, the flashing is corrected, and new stucco goes on.
4. Re-stucco larger areas. When damage covers a large part of a wall, replacing the stucco on that wall can cost less than patching it piece by piece. See stucco replacement.

Your local Stucco HQ contractor finds the source in person and puts the repair and the price in writing, free, before any work starts. See how a stucco repair works.

Keeping Water Out

• Check the sealant joints around windows and doors every year or two, and reseal any that have cracked or pulled away. Our caulk guide covers which sealant fits each joint.
• Keep soil and mulch below the weep screed, and never caulk or paint it shut.
• Aim sprinklers away from the walls.
• Seal cracks wider than a hairline: see stucco crack repair products.
• Keep gutters and downspouts clear and pointed away from the walls.

Frequently asked questions