How To Repair Cracked Plaster Walls


In order to repair cracks on walls, you must know whether you have plaster or drywall, which are also known as sheetrock, plasterboard, or wallboard. For Plaster walls or drywall cracks normally occur when you hammer a nail into then, accidently bump your wall when moving furniture or even from a minor earthquake. This type of crack in plaster walls can be repaired and does not require special skills and you only need minimal tools. This article will show you some of the tips to help you to repair cracked plaster walls.

What you need:

  • Dust mask
  • Carbide Tipped Scoring Tool
  • Vacuum Cleaner
  • Fiberglass Mesh Tape (also known as patching tape or joint tape)
  • Setting Type Joint Compound like Easy Sand 90
  • Premixed Joint Compound like the Plus 3
  • 6-inch Taping Knife
  • 12-inch Taping Knife
  • A couple of 5-gallon Buckets
  • Medium Grit Sanding Sponge


  1. Firstly, you need to open the cracks by using a carbide tipped scoring tool or a utility knife, but make sure that you do not cut through your wood lath.
  2. Remove dust from around the cracks (especially for a large crack) using a vacuum cleaner until it is free of dust or debris. The loose dusts or debris normally prevent your new plaster from bonding along with the existing plaster.
  3. Mix some setting type joint compound with a medium consistency. Once you are done mixing it, you need to force the mixture into your cracked walls and wood lath by using 6-inch taping knife. Make sure that it is not too thick and not too thin.
  4. Leave the joint compound to set thoroughly before applying the fiberglass mesh tape (also known as patching tape or joint tape) onto the affected area on your walls. You should use yellow or blue colored tape so that it is easy to see and ensure that when you apply the tape, it is in straight lines. Do not try to curve the tape because if it is not straight, the tape will buckle.
  5. Now apply two or three coats of pre-mixed joint compound. Spread them thinly over your fiberglass tape. Use water in order to thin the joint compound because the thinner you manage to spread the compound, the easier the application and the smoother the finish. Then, leave overnight to allow the compound to dry completely especially between coats.
  6. Once the final coat has fully dried, proceed with the sanding process in order to make it smooth with the help of a medium grit sanding sponge. This must be primed using a good quality latex primer such as drywall primer or PVA primer before you start to paint the wall.
  7. Whenever you mix powdered plasters or when creating plaster dust, make sure you always wear a dust mask because plasters contain lime that can do damage to your lungs once you breathe them.


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  1. Pingback : How to Prepare Plaster Walls for Painting | DIYit

  2. April 17, 2013  4:09 pm by Ian Lewis Reply

    I live in a double brick house that was built in 1887. The inside walls in just 2 rooms have had a number of cracks repaired and it cost a packet. The guy said it would crack again because of the soil under the house.
    Ok, 12 months later, two large cracks have appeared in 2 walls again. What do I do? Cover with wall paper? fill the cracks again? repl;ace the walls?

    • April 17, 2013  5:12 pm by DIYit Team Reply

      Hey Ian,
      This sounds like you have a relatively serious drainage issue where water is building up and displacing the soil causing instability in the wall. You might need to get a specialist in to see what cost effective drainage options you have to protect not only the infrastructure of your wall but your entire house.
      We appreciate this is not a cheap option but there is a point at which you simply need to bring in an expert to correct an issue for the safety of you and your family.

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