How To Repair Broken Stucco

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

When properly installed, stucco (a cement- or lime-based plaster) is about as carefree and long-lived a cladding as anyone could wish—100 years is not uncommon. Simply when big cracks or blisters appear, the fourth dimension to make repairs is right away, before the harm grows.

Antonio DiSilva of MJM Masonry performed the remedial piece of work on the East Boston house over x days, ripping off loose fabric and patching it with three separate coats. Hither's how to brand stucco repair that lasts.

Stucco Recipes

Stucco Recipes

First coat:

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

Second and finish coats:

1⁄2 bag (47 lbs.) portland cement
eight shovels amass sand for concrete
one shovel hydrated lime
1⁄ii cup acrylic bonding amanuensis

Directions:

Shovel the dry ingredients into a wheelbarrow and blend them with a mortar hoe.
Add the acrylic bonding agent, then stir in h2o, a little at a time, until the mix reaches the consistency of buttercream frosting.
Too much h2o volition make information technology loose and unworkable.
Once water is added, the mix will stay usable for thirty to 90 minutes before it starts to harden.

Watch The Weather

Freezing temperatures can ruin wet stucco. Wait for nighttime temperatures that stay above 40 degrees before tackling repairs. Hot, dry out, windy conditions can as well interfere by sucking out moisture the mix needs to cure properly. Piece of work in the shade so the stucco doesn't dry too fast. Between coats, keep the patch moist by covering it with a plastic sail.

Work Safely

The alkalis in wet cement can cause burns. Then when working with fresh stucco, wear gloves or affect the mix merely with your tools, non your fingers. Keep a bucket of water nearby to wash any splashes off your skin.

End It Right

No patch, no thing how expertly textured, will match the color of the onetime stucco around it. To do that, y'all 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 acceptable coatings include concrete paints and stains, mineral paints, lime washes, and "fog coats" of pigmented cement. Whichever blanket you use, brand sure it's alkali metal tolerant and permeable to water vapor. Otherwise, information technology will be peeling off in no time.

Steps for Repairing Stucco

Step 1: Suspension Off Loose Stucco

Whack it with a hammer, or a hammer and a cold chisel, taking intendance not to harm the underlying wood board supports. Middle protection is a must.

Step 2: Chip Away At The Edges

Continue until y'all achieve stucco that's firmly adhered to its lath. Cutting any metal mesh with snips.

Stride iii: Cover The Exposed Lath

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

Step 4: Add Mesh

Place galvanized metallic lath over the paper and trim information technology tight against the edge of the stucco. Snips with offset handles volition make this job easier. Drive more roofing nails through the mesh and into the wood lath.

Footstep 5: Mix The Stucco

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

Stride 6: Sling It

Wet the edge of the old stucco so it won't suck moisture out of the patch and weaken the bond between old and new. Scoop fist-size wads of wet stucco onto a brick trowel and toss them against the wire lath until it'southward completely covered. Smoothen the mix with a finishing trowel, and then pack it confronting the edge of the existing stucco with a brick trowel. Keep adding more fabric until this layer is about one/ii inch below the existing stucco surface.

Step 7: Scratch It

When the patch loses its wet sheen, score its surface to improve the bond to the adjacent glaze. Tape a plastic sail over the patch to proceed it from drying out.

Step 8: Apply Second Coat

Await seven days, then remove the plastic and mist the patch with water. Mix up a batch of stucco following the second-coat recipe, and trowel on a 3/eight-inch-thick coat, working from the bottom up. Pack downward the edges with a brick trowel. Await for the moisture sheen to disappear, and then trowel the patch smoothen, just beneath the level of the existing stucco. Cover again with a plastic sheet.

Footstep 9: Put On The Finish Coat

After three days, remove the plastic, mist the patch, and mix upward a fresh batch of stucco, following the cease-coat recipe. Different textures require dissimilar techniques. To match this wall's original "dash" cease, DiSilva scooped small globs of moisture mix onto his brick trowel, then flicked them against the wall until they were flush with the former surface.

Step 10: Wait To Paint

Permit the patch cure for a week before painting it and the rest of the wall. Under a glaze of heavy-bodied acrylic elastomer, the patch is invisible.

Tools:

Source: https://www.thisoldhouse.com/siding/21016528/how-to-repair-stucco

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