Q: When a downspout was replaced on my home, a small amount of stucco was torn away from the building. The plumber duct-taped plastic sheeting to the area as temporary protection. I’d like to repair the stucco myself and wonder if the prepared stucco available in the hardware store will provide a good quality and durable repair, and whether any special preparation of the damaged area is required.
My home was built in 1939 and, as far as I know, its stucco is original.
A: This is a job you can easily do yourself, and we applaud your willingness to give it a try.
Depending on the size of the hole and the amount of loose stucco and wire lath that is visible, you’ll probably need to chip out a little more stucco. It’s important to remove all loose stucco from the hole. It’s also important to have enough wire lath exposed so that you can pull it away from the wall. Also, a ragged outline is best to hold the patch. No straight lines allowed. Cracks tend to form on straight lines.
If the hole is clear of debris and the lath, and underlying building paper is intact, you’re good to go. If the paper is damaged, simply insert a piece of building felt to cover the hole. Cut a horizontal slit in the paper and insert the new piece under it so that any water getting between the stucco and the paper will continue down the paper and not penetrate behind the paper. Caulk the paper in place with latex caulk for a better seal.
Pull the wire lath away from the wall enough so that you can nail the wire to the sheeting with a lathing nail. A lathing nail has a cardboard spacer allowing the wire lath to be held away from the wall.
Premixed stucco patch is fine to use for this small a job, but we like to enrich the mixture with a little Portland Cement. We’ve found it forms a better bond and allows the stucco to stick better. It also makes for a stronger mix.
Depending on the size of the patch you’ll need two or three coats. Don’t try to get by with one coat. It will be too thick and could crack. Once the lath is prepared (debris removed and wire nailed and held away from the wall), mix the stucco.
For a two-coat job, mix enough stucco to make a 3/8-inch layer in the patch area. Wet the surface with water. A spray bottle does the job. Then apply the stucco, making sure to leave it 3/8 inch below the finished surface. Pay attention to the edges of the patch. There’s a tendency to get a little thick there.
Special tools are not required. The idea is just to get the mixture into the hole. A 4-inch drywall knife or something similar works well for applying the stucco.
Score the surface in a crosshatch pattern. Usually a nail works for this.
Allow the first coat to dry for a day or so. Then repeat the process for the finish coat, making sure to level the patch with the existing wall.
If the patch is more than 6 inches square, it should be a three-coat job. Reduce the thickness of each coat proportionately. Since stucco is usually about 3/4-inch thick, each coat should be about 1/4-inch thick. Just repeat the process three times instead of two.
Your 1939 vintage house probably has many coats of paint on it. Because of this, the raw stucco will require more than a coat or two of paint. Stucco and block sealers are available at paint suppliers.
They are about the consistency of marshmallow cream and will allow you to approximate the look of your house’s 67-year-old finish. Apply a coat or two of the coating, let it dry and finally apply a finish coat of paint.