What’s the Deal With Stucco
Stucco is an attractive and cost-effective exterior veneer system, but it has developed a bad reputation over the past couple decades because of many failures and problems with water intrusion. Many lawsuits have been filed against builders and contractors for alleged defective installation of stucco and its synthetic, prefabricated cousin EIFS. The claims and lawsuits have continued for nearly the past twenty years. CNX has acted as an expert on several stucco claims over the past several years for insurance companies and law firms. The problems with many of the claims we see are varied and often include inadequate flashing around windows, doors, and chimney extensions above rooflines, inadequate or absent control and expansion joints, and cracks in stucco that allow water to intrude. However, one problem is nearly consistent across the board – inadequate or absent drainage at the bottom of an exterior stucco or EIFS façade. Stucco is a cementitious material and is not waterproof. Water can pass through cement material especially after a coating like paint wears away. This is generally not a major problem provided the water can drain behind the stucco veneer and exit at the bottom of the wall. When water stagnates at the bottom of a stucco system, it begins to deteriorate any waterproofing layer and the exterior sheathing, and eventually makes its way into the wall cavity and into the building. However, we continue to see stucco installed, even recently, without adequate drainage. A drainage mechanism called a weep screed (rendering) will allow water to exit at the bottom of stucco walls and greatly reduce the risk of stagnant water behind the system and the eventual intrusion through the wall cavity. So, perhaps surprisingly, we don’t recommend abandoning a proposed stucco system in a new construction or renovation, but rather, make sure there is adequate drainage in the system. Stucco is a suitable system that has been used for literally thousands of years, and it looks great, but you gotta have that drainage.
