How to repair large cracks in a wall

If you have large cracks in a wall then you should first diagnose the problem. Large cracks can be the result of minor settlement and heave when the wall reacts to the ground it's been built upon as it moistens and dries out. Cracks in walls are also caused by new tree roots, leaking drains and guttering or other flaws around features in the wall like windows and chimneys. Once you've determined why the crack has appeared in the first place and fixed that issue, you'll be ready to repair the crack itself…

Level of difficulty

Level 1: Beginner

What you need

  • Dust sheet
  • Damp cloth
  • Patching compound
  • Caulking gun
  • Plaster
  • Trowel
  • Sandpaper

The steps to follow

  1. Cover the work area with a dust sheet.
  2. Remove any chipped parts from the crack and clear away any debris. Make sure it is free from dirt and debris so that the patching compound and plaster can adhere properly.
  3. Wipe the area with a damp cloth.
  4. You can use a putty knife and apply patching compound to the crack, or fill a caulking gun with patching compound and use it to fill the crack.
  5. Wipe off any excess patching compound.
  6. Let it set and dry.
  7. Smooth the surface with fine grade sandpaper.
  8. Use a trowel and apply a thin layer of plaster to the surface.
  9. Smooth the surface with fine grade sandpaper.
  10. Apply a coat of primer to the newly plastered area.
  11. Let it dry before you start painting.

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Don't want to DIY? Get recommended plasterers for your home improvement job.

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