Here’s how to fix your plaster walls

Here’s how to fix your plaster walls

There are many reasons why your house’s plaster walls may start to disintegrate. Some of the causes are plumbing leaks, settling of the house, wall hangings, or natural disaster.

Minor cracks on plaster walls may be the result of the house settling, but if you don’t repair them immediately, you could endanger the safety of your home.

If you want to repair small cracks in plaster walls, here are the steps:

Small cracks

  1. Use the point of a lever-type can opener, a screwdriver, or a utility knife to widen the crack to about three millimeters.
  2. Brush the cracked area with a solution of water and trisodium phosphate (TSP) or a non-phosphate detergent with a medium-bristle brush.
  3. Cover groove with short pieces of self-adhesive fiberglass mesh.
  4. Dampen the cracked area with a clean wet sponge.
  5. Cover the groove using a 3-inch-wide putty knife with some setting-type joint compound. Smooth it evenly and let it dry.
  6. Apply another layer of joint compound smoothly on the groove with a drywall knife or a wide-blade putty knife. Allow it to dry
  7. Sand the edges lightly to blend the patch into the wall.
  8. Prime with high-quality latex primer and paint.

plaster wall lafarge prosolutions

Large cracks

  1. Widen the crack with a can opener and wet the edges of the crack with a sponge.
  2. Fill the crack half full with patching plaster. Score the plaster with a nail after it has dried.
  3. Wet the patch again and apply another layer of patching plaster to about a quarter of an inch of the surface.
  4. Apply a layer of finishing plaster after the previous patch dried.

Sagging walls

Sagging is the first sign of the collapse of a plaster wall. Sagging walls are a more complicated problem compared to flaking and cracking plaster walls.

This problem occurs when plasters dry out or weaken after many years, and they start to fall apart. Lath, or the base made of wood or metal wire mesh, can also pull away from the framing.

If your wall or ceiling is sagging, it’s best to contact a professional for repairs as it is a difficult job. However, here are the steps if you want to fix them yourself:

  1. Protect your flooring and place damp or plastic sheets over doorways. Build T-shaped supports to hold a piece of plywood flat against the ceiling if you are worried that the ceiling will fall apart.
  2. Chip out a small area of the edge of the bulge with a hammer and a cold chisel. You can tell if the plaster is separated from the lath, or if the lath is pulled away from the frame after breaking through the surface. You can try to refasten the mesh to the frame without removing the plaster if it is still well-adhered.
  3. Penetrate the wood frame with long drywall screws. Start near the edge of the bulge and press the ceiling upwards as you drive the screws. This step may be impossible if the lath is warped or if the old nails are keeping the frame away from its original position.
  4. Remove the old plaster if the lath is anchored to the ceiling joists and the plaster has pulled away.


Fixing cracks on plaster walls isn’t a difficult task. All you need the right tools and don’t be afraid to get dirty!

Repairing your walls on your own is admirable but for more serious cases, seek professional help to avoid damaging your walls. Visit if you need help with fixing your plaster walls!