Best Practices and Quality Issues in Residential Stucco Application

In the Western U.S., three-coat and one-coat stucco are the dominant exterior finishes for residential construction. Still, stucco is present in almost every market. While the use of stucco is widespread, it has performed poorly in recent years due to the improper execution of key details.

This paper closely examines what has been learned from extensive on-site inspections and lab tests of both durable and failed stucco systems. In particular, it looks in detail at: Installing the drainage plane, bond break, and lath Selecting and storing the raw materials Mixing and applying cementitious stucco Applying the scratch coat or base coat, including the similarities and differences when applying one-coat and three-coat stucco Executing and testing hydration Applying the finish coat

Best Practices for applying stucco have been developed by extensively studying each of these components. In addition, important details have been created for key areas like horizontal surfaces, architectural accents, and transitions to other exterior finishes. By having a shared knowledge base, designers, specifiers, trades, and site supervisors can work together to produce a durable stucco finish.