Cracking or crumbling plaster walls are a nuisance to the structure and beauty of a wall. Though it may be tempting to replace damaged plaster walls with plasterboard, salvaging the plaster walls with a new coat of plaster and fibreglass mesh tape can save time and money. The key to repairing plaster walls is to completely expose and remove all of the damaged sections to lay a safe and effective adhesion surface for the new plaster.
Remove any loose plaster from the wall with a putty knife.
Sand the plaster around the hole smooth with an angle plane.
Brush on a bonding agent over any exposed lath and any plaster to be recoated.
Cover small cracks with fibreglass mesh tape.
Mix the plaster according to the manufacturer's directions.
Apply the plaster over the damaged section with a trowel. Press firmly to pack the plaster into every crevice. Press the plaster into the lath to leave a slight depression, to be filled in with a final coat.
Cut out a piece of fibreglass mesh tape large enough to cover the hole. Press it into the wet plaster with the trowel.
Apply a second, skim coat of plaster over the mesh tape to cover the tape and leave the surface smooth and even.
Smooth over any rough patches with a damp sponge. Let the plaster set for 30 minutes.