Exterior grade plaster, also known as stucco, is a cement-based finishing material. Plaster comes in a dry form that when mixed with water creates a heavy paste. Contractors and homeowners apply wet plaster by hand or with a machine to the exterior of a home. As the plaster dries, it forms a strong and durable outer shell on the house. Exterior grade plaster is available in a variety of colour and texture choices. It is a popular choice in home finishing because it can withstand hot summers and cold winters without issue. Damage may occur to the plaster because of accidents, house settling or when gaining access to areas lying behind the solid masonry.
Remove loose or broken plaster by hand until you are unable to break more away.
Create a squared-off region around the broken plaster with a masonry cold chisel and hammer. Chip away an area 2 inches larger than the damage in all directions.Brush the dust and debris away from the hole with a small hand-held broom.
Measure and cut a piece of metal mesh screening to the exact size of the hole. Use metal shears to make cuts to the screening. Secure the metal mesh inside the hole with heavy-duty galvanised staples or galvanised nails.
Mix the plaster with water in a bucket to create a thick paste-like consistency.
Brush a light coat of an epoxy-based bonding agent to the edges of the hole.
Dip a trowel into the plaster, pressing it into the metal mesh. Use enough plaster to fill in half the depth of the hole. Drag the notched edge of a trowel through the wet plaster to create ridges. Dip the trowel into the plaster and apply a second coat of plaster over the first coat. Build the second coat up so that it is flush with the existing plaster.
Remove loose pieces from the crack with your fingers. Insert a pointed trowel into the crack and scrape downward to remove more loose pieces without widening the crack.
Brush away dust and debris with a hand-held brush or small broom.
Mix the exterior-grade plaster with water in a bucket to develop a paste-like consistency.
Apply a light coat of an epoxy-based bonding agent to the edges of the crack.
Dip a flexible putty knife into the plaster. Press the plaster into the crack deeply and build it up to finish flush with the existing surface.
Wear a dust mask, safety goggles and gloves when repairing exterior-grade plaster.