A. Steve Thomas responds: Several things make this type of job very challenging: It can be difficult to finish the wall on the same plane as the existing stucco. You’ll undoubtedly wind up with shrinkage cracking around the perimeter of the old opening. And most challenging of all, it’s extremely difficult to match the color and texture of existing weathered stucco with a new mix.
It’s likely the existing coating on the foundation is a multi-layer cement parge coat, and not true stucco. True stucco contains white waterproof cement, lime, and silica sand, and is applied over metal lathe. Each coat is mixed to different strengths, starting with the scratch coat, which has the highest cement content for the highest strength....
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