In this video, This Old House general contractor Tom Silva explains how to patch plaster.
Steps for patching plaster walls
- Measure area of plaster wall that's loose or damaged and needs to be replaced.
- Cut a drywall patch slightly larger than the damaged wall section.
- Hold drywall patch against plaster wall, and mark its outline with utility knife.
- Using a utility knife, score the plaster along the patch outline.
- Pry off the loose plaster with a painter's tool; clean up the debris.
- Set the drywall patch against the wall and secure it with 1 ¼-inch drywall screws.
- Cover the seams around the patch with adhesive-backed nylon joint tape.
- Apply a thin coat of joint compound to the taped seams and to screw heads.
- Allow compound to dry, then sand lightly with 150-grit sandpaper.
- Apply a second, slightly wider coat of joint compound to the seams.
- Allow second coat of compound to dry; sand with 150-grit sandpaper.
- Apply a third, even wider coat of joint compound to the seams.
- Smooth dried compound with 320-grit sandpaper.
- Finish the wall with a coat of primer and two paint topcoats.