How to Sand Plaster Walls

Nichole Mayers

Well-preserved older homes are often characterized by their smooth plaster walls and beautiful, detailed crown mouldings.

Damaged plaster

Unfortunately, older plaster is more susceptible to cracks and crumbling and consequently, many homeowners opt for replacing plaster with drywall rather than undertaking the job of patching and repairing damaged plaster. Replacing plaster with drywall will often require the removal of the original mouldings, which can eliminate some of the home’s old-fashioned charm and is not always necessary. Plaster repairs can be easily completed by a novice.

  1. Evaluate the repair project to determine what is required. For loose or sagging plaster, secure plaster by screwing the plaster washers to loose spots with your drill. For small holes, clear loose plaster and clean the area.

  2. After loose plaster is secured to the lats, place self-stick drywall tape over the washers and using a spackle knife, apply joint compound over the tape, keeping the compound as smooth as possible. If the drywall tape does not have adhesive, apply a thin coat of joint compound to the area, place tape over the screws and washers, and apply another layer on top.

  3. Larger holes may need to be enlarged into a square and filled with drywall. Tape over drywall screws and around the edges of the drywall and spackle.

  4. For small holes, place mesh or drywall tape over the hole. If the hole is too large for tape, cut a mesh patch to size, apply a thin coat of joint compound to the wall surrounding the hole, and place the mesh over the area. Apply another layer of joint compound over the top.

  5. For cracks, place mesh or drywall tape over the crack and spackle with joint compound.

  6. Wait for joint compound to dry completely. (Color will change from pale grey to white.) Sand lightly by rubbing sanding block evenly over the patched surface. Apply another coat of joint compound.

  7. Sand lightly and apply a third layer, once the second layer of joint compound is dry.

  8. Sand with fine sanding block once the third and final layer has dried.

  9. Tip

    Wear safety goggles and face mask while sanding or clearing loose plaster. Apply layers of joint compound as smoothly as you can. This allows for easier sanding and less layers of joint compound to cover imperfections. Before painting repaired plaster, apply a layer of primer. Plaster washers may be difficult to find. Purchasing online may be the best option.