How to Improve Cracked Plaster Walls

Hairline Cracks

• 1

  Put on gloves, and mix the patching plaster with water in a container according to the manufacturer's directions. Alternatively, use premixed patching plaster.

• 2

  Cut a piece of fiberglass mesh tape to the length of the crack, plus 2 inches. Center the tape on the crack. The tape should slightly overlap the ends of the crack.

• 3

  Scoop out a generous portion of the patching plaster with a putty knife.

• 4

  Smooth the patching plaster along the tape, holding the putty knife at a slight angle to avoid gouging the wall. Skim off the excess with the edge of the putty knife. Allow the patching plaster to dry for the time recommended by the manufacturer.

• 5

  Put on a respirator mask. Sand the area smooth with 100-grit sandpaper. Wipe away the dust with a damp rag. Prime and paint the wall.

Larger Cracks

• 6

  Place drop cloths on the floor near the wall. Clear out loose bits of plaster from inside and around the crack. Go as far down into the plaster as necessary until you reach solid, undamaged plaster. Clear away bits of plaster and plaster dust with a dry paintbrush or vacuum cleaner.

• 7

  Use a small piece of drywall or plaster washers to make repairs. Cut a piece of drywall to fit and place it inside the hole. Attach the drywall to the lath with drywall screws. Alternatively, insert a drywall screw through a plaster washer.

• 8

  Slowly tighten the screw. The washer should begin to flatten out and secure the plaster as the screw tightens. If this does not occur, the screw may be located between two pieces of lath. Unscrew the washer, move it slightly to the left or right and try again.

• 9

  Place a piece of fiberglass mesh tape over the repair.

• 10

  Smooth a thin layer of plaster patching compound over the repair. Allow it to dry, and then apply one or more additional layers of plaster patch, allowing each to dry before applying the next until the repair is flush with the surrounding wall.

• 11

  Put on a respirator mask and gloves. Sand the area smooth with 100-grit sandpaper. Wipe the dust away with the damp rag. Prime and paint.