Q: I have a problem that I just can’t find the answer to. I had a new circuit breaker box put on the outside of my house. In order to do this, the electrician told me he had to knock out the old stucco in an irregular shape so that it could be repaired correctly.
He said that if he cut it out neatly, the repair wouldn’t be as strong. Now I have a new box with a big sloppy hole around it. Can you tell me how to mix and repair the stucco?
A: As we’ve said many times, home improvement isn’t brain surgery. It only takes the willingness to get your hands dirty. We encourage you to dirty your hands and repair your stucco. Your electrician is correct. If it’s necessary to punch a hole in stucco, it’s much better to leave a ragged edge because cracks form easily along straight edges.
Here’s how to make your new electrical panel look as if it’s always been there.
First, inspect the lathe, the building paper and chicken wire beneath the stucco. If the electrician has removed it, you must replace it. With a hammer, remove enough stucco around the edges to expose about 2 inches of lathe. Slide a new piece of 15-pound roofer’s felt under the existing paper and nail it in place with roofing nails.
Next, cut a piece of chicken wire to the size of the patch and attach the new wire to the old by twisting the edges together. Then nail the wire in place with stucco nails. These nails have cardboard spacers that hold the wire away from the paper and the wall. This lets the stucco embed itself into the wire, forming what is called a key.
Now it’s time for the mud. Stucco is a mixture of sand, lime and Portland cement. Dry, premixed stucco is available in boxes and sacks at hardware stores and home centers. We’ve found these to be a little light on the cement, so we suggest you add a little more cement to enrich the mixture.
Stucco is applied in three coats called a brown coat, a scratch coat, and a finish coat. Pour the dry stucco into a wheelbarrow or a 5-gallon bucket, add water slowly and mix to the consistency of toothpaste.
With a trowel (available for less than $10) apply the brown coat. Put it on thin and don’t worry if the wire shows. After the mixture has set up a little, make a crosshatch pattern on the surface with a nail. This allows the next coat to adhere to it.
Let the brown coat dry for a day or two, and then repeat the process, cross-hatching and all, for the scratch coat. Make sure to leave the surface below the level of the finished wall. Let the scratch coat dry for a day or two, then apply the finish coat. But this time, rather than scratch the surface with a nail, go over it with a wood float or the thin edge of a two-by-four to make sure the patch is level with the existing wall.
Two tips. First, we assume that your home is an older one. The new stucco will take paint differently than the existing wall, which has probably has been painted many times. Before you paint, apply a concrete block coating or similar thick product to simulate the layers of paint on the house. Second, let the finished stucco cure for two or three weeks before painting. Stucco that dries too quickly is prone to cracking.
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