A school gymnasium was built with concrete masonry and direct applied stucco. It experienced leakage and so they put a stucco on lath over the direct applied stucco. They are now experiencing more leakage and are wondering what they can do.
There are two completely separate issues created by the stucco over lath added to the structure. The first and most important issue is the nature of the fasteners used to attach the stucco on lath to the structure. The fasteners should have been stainless attached through the existing stucco into the masonry substrate. Since the structure is leaking again it can be assumed that the drainage plane between the two coatings is holding water. If the fasteners were not SS then there could be problems with corrosion.
The second issue is the leakage which, if the new stucco on lath has been properly fastened to the masonry substrate, is a matter of completely sealing all cracks and control joints and giving the stucco a few new coats of acrylic paint.
Jerry Painter, FASTM
Don Beers, PE, GC
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