Can stucco be applied over painted walls?
This is a common question that often arises when people are updating older construction. Stucco is a cost effective finish, relatively easily installed, that improves the appearance and creates a water resistant wall surface. A painted surface will not typically absorb water and, as such, is a substrate to which stucco will not bond—at least not uniformly.
There are two basic alternatives to covering a painted surface with a new coating of traditional cement stucco.
2) Attach paper backed rib lath or install appropriate building paper between wall and attached metal lath to provide a moisture barrier and to serve as a bond breaker. Apply traditional three coat stucco to the metal lath and accessories. In this approach, the idea is to treat the plaster like a sheathed system, using metal lath to support the stucco on the substrate, while completely isolating the stucco layer from the backup with 2-ply 60 minute building paper. This prevents a partial bonding situation, which could set up undesirable stresses in the stucco and lead to stucco cracking.