How To Repair Crumbling Stucco

At start glance, the seamless coat of stucco on the Eastward Boston house looked as bulletproof as a sidewalk, the perfect foil against the harsh wet weather of this coastal metropolis. Yet beneath its lush cloak of ivy, the cement shell was a mess of cracks and buckling, signs that h2o had gotten in and damaged the underlying wood lath.

When properly installed, stucco (a cement- or lime-based plaster) is almost every bit carefree and long-lived a cladding as anyone could wish—100 years is not uncommon. But when large cracks or blisters announced, the time to make repairs is right abroad, before the impairment grows.

Antonio DiSilva of MJM Masonry performed the remedial work on the Due east Boston house over ten days, ripping off loose material and patching information technology with iii separate coats. Here's how to make stucco repair that lasts.

Stucco Recipes

Stucco Recipes

First coat:

1⁄2 bag (47 lbs.) Portland cement
6 shovels brick or masonʼs sand, slightly clammy
1 shovel hydrated lime
1⁄2 cup acrylic bonding agent

Second and finish coats:

i⁄2 handbag (47 lbs.) portland cement
8 shovels aggregate sand for concrete
1 shovel hydrated lime
1⁄2 cup acrylic bonding agent

Directions:

Shovel the dry ingredients into a wheelbarrow and alloy them with a mortar hoe.
Add the acrylic bonding agent, and then stir in water, a fiddling at a time, until the mix reaches the consistency of buttercream frosting.
Likewise much water volition make it loose and unworkable.
Once water is added, the mix will stay usable for 30 to 90 minutes before it starts to harden.

Watch The Conditions

Freezing temperatures can ruin wet stucco. Look for nighttime temperatures that stay in a higher place xl degrees before tackling repairs. Hot, dry out, windy atmospheric condition can likewise interfere by sucking out moisture the mix needs to cure properly. Work in the shade so the stucco doesn't dry also fast. Betwixt coats, continue the patch moist by covering it with a plastic canvass.

Work Safely

The alkalis in wet cement tin cause burns. So when working with fresh stucco, article of clothing gloves or touch the mix but with your tools, not your fingers. Continue a bucket of water nearby to launder whatsoever splashes off your peel.

End It Correct

No patch, no matter how expertly textured, will match the color of the former stucco around it. To do that, you lot need to apply a pigmented coating over the entire surface. The patch at this house was covered with a thick, sprayed-on acrylic elastomer that bridges and seals hairline cracks. Other adequate coatings include concrete paints and stains, mineral paints, lime washes, and "fog coats" of pigmented cement. Whichever coating you use, brand sure it'due south element of group i tolerant and permeable to water vapor. Otherwise, it will be peeling off in no time.

Steps for Repairing Stucco

Pace 1: Interruption Off Loose Stucco

Whack it with a hammer, or a hammer and a cold chisel, taking intendance not to damage the underlying wood lath supports. Centre protection is a must.

Footstep 2: Chip Abroad At The Edges

Proceed until yous reach stucco that's firmly adhered to its lath. Cut any metal mesh with snips.

Step 3: Embrace The Exposed Lath

Using a utility knife, trim a piece of grade-D builder's paper to fit tightly along the purlieus where the old stucco meets the exposed wood board. Fasten the newspaper to the lath with roofing nails, then put a 2nd layer of paper on top of the first.

Footstep 4: Add Mesh

Place galvanized metal lath over the paper and trim information technology tight confronting the border of the stucco. Snips with showtime handles volition make this job easier. Drive more roofing nails through the mesh and into the wood lath.

Pace v: Mix The Stucco

Following the first-coat recipe, stir upwardly a batch of stucco, using a wheelbarrow as a mixing bowl. The acrylic bonding agent added to this mix improves the adhesion of the new stucco to the old.

Pace half-dozen: Sling Information technology

Wet the edge of the old stucco then it won't suck moisture out of the patch and weaken the bond between quondam and new. Scoop fist-size wads of wet stucco onto a brick trowel and toss them confronting the wire lath until information technology's completely covered. Smooth the mix with a finishing trowel, so pack it against the edge of the existing stucco with a brick trowel. Continue adding more material until this layer is about 1/2 inch beneath the existing stucco surface.

Step 7: Scratch It

When the patch loses its wet sheen, score its surface to improve the bond to the side by side glaze. Tape a plastic sheet over the patch to go on it from drying out.

Step 8: Apply Second Coat

Wait seven days, so remove the plastic and mist the patch with h2o. Mix up a batch of stucco post-obit the second-coat recipe, and trowel on a 3/8-inch-thick coat, working from the bottom up. Pack down the edges with a brick trowel. Look for the moisture sheen to disappear, then trowel the patch smooth, just beneath the level of the existing stucco. Encompass again with a plastic sheet.

Step 9: Put On The Finish Coat

After 3 days, remove the plastic, mist the patch, and mix upwards a fresh batch of stucco, post-obit the cease-glaze recipe. Different textures require different techniques. To match this wall's original "dash" finish, DiSilva scooped small globs of wet mix onto his brick trowel, then flicked them confronting the wall until they were flush with the old surface.