Stucco Repair: How To Fix Cracks and Blisters

Stucco is known for its durability, but does that make it maintenance-free? Not quite. With wear-and-tear over time, the surface can develop cracks, and there may be holes that need filling. Don’t ignore them.

To make your stucco exterior last as long as it should, it’s imperative to seal any areas where moisture might come in. Follow these instructions for making repairs and preserving the outside of your home.

Tools

Caulk gun;

Hammer or chisel;

Putty knife;

Staple gun (optional);

Stiff paint brush;

Tin snips;

Trowel;

Wire-bristled brush.

Materials

Acrylic exterior caulk;

Exterior paint (optional);

Lath nails or roofing nails;

Stucco repair mix (pre-mixed or conventional).

How To Repair Small Stucco Cracks

It’s not uncommon for small “hairline” cracks to appear over time in stucco siding. Fortunately, they’re easy for homeowners to repair, says Gregg Cantor, president and CEO of Murray Lampert Design, Build, Remodel in San Diego.

Sometimes they can be filled in with paint. But if that doesn’t work, follow these steps.

Step 1: Clean the Area

Lightly brush away any dirt around the crack with a stiff paint brush.

Step 2: Fill the Crack

Use an acrylic exterior caulk to fill a crack no wider than a dime. Use a sanded acrylic exterior caulk for cracks up to 1/4-in. wide. Smooth the caulk with your finger.

Step 3: Finish

Let the caulk dry according to manufacturer’s instructions, then paint the stucco as needed.

How To Repair Larger Stucco Cracks or Small Holes

To repair a larger crack (1/4-in. or slightly wider) and small holes (like those left from bolts), you’ll need to do more prep work and use a different repair product. Cantor notes that the occasional larger crack isn’t uncommon. But if you have a lot of them, he says, there could be something more serious going on. In that case, call a professional stucco contractor to troubleshoot.

Step 1: Clean the Area

Use a putty knife or scratch awl to scrape out loose debris from the crack.

Step 2: Fill the Crack or Hole

Apply a premixed stucco patching material with a putty knife.

Step 3: Add Texture

Use a wire-bristled brush to add texture to the patch and match that of the existing stucco.

Step 4: Finish

Once the patching material has dried (follow manufacturer’s instructions), paint over the patch if desired.

How To Repair Larger Areas of Damaged Stucco

If there’s a damaged area of stucco larger than a small hole — say a square foot or so — you may be able to do the repair work yourself. “The biggest challenge,” says Cantor, “will be getting the texture of the stucco repair to match the existing texture.”

One caution before you start: Cantor says be sure the damage isn’t due to faulty installation or moisture that’s somehow gotten behind the stucco. For those situations, call a stucco pro.

Step 1: Remove Loose Stucco

Using a hammer or chisel, remove all the damaged stucco and debris, as well as some undamaged stucco around the repair area.

Step 2: Remove Lath and House Wrap

Remove the lath with tin snips and cut away the house wrap or felt paper near the damaged stucco. But leave the lath and wrap behind the good stucco that you removed.

Step 3: Install New House Wrap and Lath

Cut a piece of house wrap or felt paper to match the size of the area being repaired. Secure it firmly to the studs or sheathing with a staple gun. Make sure it overlaps the wrap on the margins that you left intact. Seal around the wrap seam with acrylic exterior caulk.

Using tin snips, cut a piece of metal lath the size of the repair area. Staple it to the wall or attach with lath or roofing nails.

Step 4: Apply the First Stucco Repair Coat

You can use pre-mixed stucco repair mix, which is ready to trowel on, or conventional stucco repair mix, which needs to be mixed in a wheelbarrow or plastic tray following manufacturer’s instructions. Either way, look for a mix that cures rapidly.

Apply the first coat, called a “scratch” coat, with a trowel. Etch the surface of the stucco material with a putty knife or trowel; this will help the next coat adhere to the first. Let dry according to the manufacturer’s instructions.

Step 5: Apply the Second Coat

Prepare the stucco mix and apply the second coat, called a “brown” coat, to the area. Etch the surface of the stucco with a putty knife or trowel. Let dry.

Step 6: Apply the Third Coat

Apply the last coat, called the “color” coat, to the patched area. Use a stiff-bristled brush, broom or other implement to create a texture that matches the existing stucco. Be sure to practice your texturing technique before you apply this last coat.

If you’re repairing stucco that has never been painted, use colored stucco mix to match your existing color. If the stucco has been painted, use the same stucco mix you used for the first two coats.

Blisters in Stucco?

If your stucco has bubbles on the surface, because the paint has blistered or the stucco itself is bubbling, call a stucco pro. “This could be a sign that there’s a moisture problem and repairing the blister won’t be a permanent fix,” says Cantor.

Stucco Repair and Maintenance Tips

• Inspect your siding at least annually to spot cracks, holes or areas where stucco may be deteriorating. Repair it as soon as you can to avoid more extensive damage.
• Prevent moisture damage to stucco by making sure the soil around your home doesn’t reach the stucco, says Cantor. “Because stucco is porous, it will take up moisture from soil that’s touching it and that can lead to deterioration of the stucco,” he says.
• If your stucco needs a refresh, follow these steps for painting stucco.

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