The seamless stucco coating on an East Boston home looked like a sidewalk. It was the perfect foil for the coastal weather. But beneath the lush cloak, the cement shell showed cracks and buckling. This was evidence that water had penetrated and damaged the wood lath underneath.

Stucco (a lime- or cement-based plaster) can be installed correctly and lasts for as long as 100 years. However, if you notice cracks or blisters, it is important to repair them immediately before further damage occurs.

Directions:

• Mix the dry ingredients in a wheelbarrow.
• Mix the acrylic bonding agent with water. Add additional water as needed until the mixture resembles buttercream frosting.
• Too much water can make it unworkable.
• The mixture will remain usable for between 30 and 90 minutes after the water has been added. It will then begin to harden once it is cooled.

Weather Watch

Wet stucco can be damaged by freezing temperatures. Before you tackle repairs, wait for nighttime temperatures to reach 40 degrees. The mix can be affected by hot, dry, and windy conditions. To ensure that the stucco does not dry too quickly, work in the shade. Cover the stucco with a plastic sheet between coats to keep it moist.

Work Safely

Burns can be caused by the alkalis found in wet cement. When working with fresh stucco, use gloves and only touch it with your tools, not with your hands. To wash off any splashes, keep a bucket of water close by.

Do it right

No patch, regardless of how well-textured, can match the color of the stucco surrounding it. You need to paint the entire surface with a pigmented coat. This house had a patch of the roof covered with an acrylic elastomer, which seals and bridges any hairline cracks. Concrete paints and stains are acceptable, as well as lime washes and fog coats of pigmented cement. No matter what coating you choose, ensure it is alkaline-tolerant and water vapor permeable. It will soon start to peel off.

Steps to Repair Stucco

Step 1: Remove loose mortar

Step 2: Chip away at the Edges

Step 3: Cover the Exposed Lath

Step 4: Add Mesh

Step 5: Mix the Stucco

Step 6: Sling it

Step 7: Scratch it

Step 8: Apply a second coat

Step 9: Add the Finish Coat

Step 10: Wait To Paint

Allow it to dry for at least seven days before you paint it or the rest of your wall. The patch will disappear under a thick coat of acrylic elastomer.