Why Do Seaside Homes Experience Greater Exposure To Stucco Damage Than Other Properties?
Though liquid water cannot pass through the cement matrix of stucco that has been properly installed, moisture (as opposed to liquid water) can permeate to some degree into this matrix – especially when driven by horizontal winds from the sea. Winds that come from the sea can be salt saturated causing chlorides to enter the matrix allowing the chemical reactions from the chlorides that cause the metal lath and accessories to experience accelerated corrosion, and the cement stucco matrix to deteriorate and loose strength.
Is Stucco A Good Building Envelope Material For Seaside Environments?
Portland cement plaster is suited to virtually every type of climate, whether wet or dry and hot or cold. It is popular in coastal environments because it is unaffected by moisture, but when metal lath is part of the system, there are potential concerns due to the elevated chloride levels in the environment.
In coastal areas, air is literally salty: it carries chlorides. This is an aggressive ion that corrodes metal. Hardened plaster is not affected by chlorides. Typical 3 coat stucco includes metal lath and accessories like corner bead, etc. The combination of galvanized coating and plaster cover protects the metal. However, the metal lath and accessories, despite being galvanized eventually may be subjected to the effects of the chlorides – especially if substantial cracking of the stucco is present.
Despite these concerns, you will be hard pressed to find a building envelope material in a seaside environment that is superior to stucco.
What Can Be Done To Reduce Early Deterioration Of Seaside Properties?
Finish coat systems that are acrylic based can be substituted for conventional stucco finish coat. These acrylic based finish coat systems can completely prevent moisture from ever entering the stucco matrix and the result can be a profoundly longer life for the stucco system in these vulnerable areas. Additionally, new components incorporating new technologies can be substituted for the old more vulnerable components are now available. These products include lath that is made of fiberglass, new corner bead and “weep screeds” that are made of vinyl, which is not subject to corrosion or degradation in these environments.