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:
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.
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.
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.
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.