Stucco is an exterior finish material made from sand, cement, and natural lime. This material offers a highly textured, versatile finish option for any type of surface, including brick and other forms of masonry. Builders and homeowners often apply stucco over brick or masonry walls to cover ugly or damaged surfaces. Because brick is so porous, the surface must be carefully prepared to ensure the stucco application will be successful.
The first step to applying stucco over brick is to add or repair flashing around doors and windows. Any incomplete or damaged flashings around these openings can lead to moisture damage after the stucco has been applied. Next, the walls should be cleaned to ensure all dust and contaminants have been removed. This is often accomplished by power washing or pressure washing. Finally, any major repairs should be complete, including replacing missing brick or mortar, or removing loose or crumbling sections.
When applying stucco on brick, it's helpful to wait for the right weather to avoid problems with freezing as the stucco dries. Apply a concrete bonding agent using a paint brush or roller, then allow this bonding agent to cure according to the manufacturer's instructions. This type of agent helps to seal the brick, allowing the stucco to bond securely.
Wet the entire wall with a garden hose before attempting to apply stucco over brick. Mix the stucco according to the instructions on the package, then use a trowel to apply the first coat to the wall. Start with a 1/4-inch (6.35 mm) scratch coat. After this coat has dried for a few hours, run a plasterer's rake over the stucco to create a lined texture.
Give the scratch coat one or two days to cure, then apply a second coat of approximately the same thickness. Use a trowel to vary the texture and create the desired appearance. Keep the stucco moist for the first week so it will dry slowly and resist cracking. Wait at least four to six weeks before attempting to paint fresh stucco.
While it's fairly easy to apply stucco over brick, it's often more of a challenge if the brick has been painted. Before attempting this type of application, sandblast the paint to reveal the raw surface of the brick. This increases the strength of the bond between the stucco and the wall surface. If sandblasting is not an option, add a metal lath to help the stucco better adhere to the brick.