Stucco Failures and Remediation

Stucco over a single wythe of concrete block is widely used as wall construction in parts of the country with hot humid environments and heavy rains. Water intrusion has frequently been observed in this type of construction. This paper will identify the sources of water intrusion and describe alternatives for preventing or correcting such intrusion. Observations of water movement into and through wall construction will be described. Wall assemblies that are successful, as well as those with observed defects, will be described. Defects causing water intrusion into the building or damage to the exterior surface will be discussed, including water and insect passage through stucco accessories such as expansion joints, control joints and corner beads; water intrusion where walls sit on solid structures such as concrete bond beams or slabs; corrosion of stucco accessories; and efflorescence at stucco accessories.