How to Repair a Large Crack in Plaster

1 Material
4 Days

In preparation for redoing out upstairs playroom, I repaired a large crack in our plaster (we’re in an old home).
When Repairing a Crack in Plaster you can essentially thinkof this task as being broken down into two parts.
1. Securing Loose Plaster
2. Finishing the Repair.
For this project, I used a product called *Big Wally’sPlaster Magic* and I finished almost as if I would if I were repairing drywall. (maybe some helpful info for that too.)
I made a video and had great fun working with my 8year old daughter Eva (again). ( You can find out more about the back story by viewing our site.

One Additional Note: when working with older plaster walls lead & even asbestos is of course a possibility. be safe and work cautiously.

Thanks and hope it helps. ~jb
How to Repair a Large Crack in Plaster
Using Big Wally's Plaster Magic.
Start by Drilling 5/16" holes 1 or 2 inches from the crack and about 3 inches apart. Use a Masonry Bit.
Apply adhesive using a caulk gun squirting into holes and cleaning up with a sponge. Tip: cut only the tip of the tub off.
Installing plaster washers using a 2" inch drywall screws into some of the holes.
Let dry overnight and remove washers.
Using a 4" drywall knife, fill the crack and holes.
Use a mixable powdered drywall compound. Many actually contain plaster and will shrink less.
Install a Crackstop Mesh over the entire affected area.
Skim Coat and Sand Lightly. 2 coats are recommended.
clean and prime.
Video :: Complete Instruction for Repairing a Large Crack in a Plaster Wall.

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Want more details about this and other DIY projects? Check out my blog post!


Have a question about this project?

3 of 4 questions
  • Hales Newson
    Hales Newson
    on Sep 12, 2017

    what is the point of drilling holes either side
    • Nancy
      on Sep 14, 2017

      Gives the plaster somewhere to sink into and hold better, think fingers. That way it will not peel off.
  • Kelly
    on Aug 29, 2018

    Hi. Can anyone advise if this is a plaster crack please?

    • Biff
      on Feb 23, 2020

      True story, I knew a chick once who had a crack like that, that ran from her belly button all the way to her tail bone, strange.

  • Sulyman
    on Jul 22, 2019

    Well done sir, pls can I use reinforcements bar to repair crack in wall

Join the conversation

2 of 14 comments
  • Stella Love
    Stella Love
    on Nov 6, 2018

    Easier way? Scrape out the crack. Fill with drywall mud. Put fiberglass tape over it and finish as if it was drywall. Crack will not come back.

  • JoAnn Green
    JoAnn Green
    on Apr 17, 2019

    Yes I willl Try, I have a large wall that termites got into, the plaster is off it. Would I use this method to fix my wall? Where can I get the big Wally? Thanks for any help.

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