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.
Suggested materials:
  • See Related Article. Linked
Building Moxie
Want more details about this and other DIY projects? Check out my blog post!
Frequently asked questions
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

  • Kelly Kelly on Aug 29, 2018

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

    comment photo
  • Sulyman Sulyman on Jul 22, 2019

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

Join the conversation
2 of 16 comments
  • 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.

  • Stella Love Stella Love on Jan 05, 2021

    If it's failing that's different. Knockout all the loose plaster and fill hole with a piece of drywall, tape and mud. Whatever the person is doing in the article is nuts.