How to fix cracks in the walls

Find out how to spot symptoms of structural damage and how best to fix cracks in walls.

11 July 2019

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Floor and surface cleaning

Repairing cracks in the walls of your house is key to keeping it look smart and homely. This article will provide a guide to making sure it's not a symptom of a larger structural problem first plus how to fix cracks in walls so they look good as new! If you’re looking for tips to fix holes rather than cracks, we have a great article you can read if you click here.

Always lay down old sheets to protect the floor and vacuum the wall and floors to clean up any mess made when repairing cracks in the walls of your house.  

Cracks in walls: how to spot if a crack is a symptom of a larger structural problem

Fixing minor cracks can be done yourself. You can patch, fill and fix them with our guide. However, major fissures can be a sign of more significant structural damage. You can’t simply paint to cover cracks such as these. Look out for:

  • Horizontal cracks which stretch the length of a wall.
  • Walls bulging.

Be sure to call in a professional to repair these types of cracks.

How to fill cracks in walls of all types

Did you know you are only likely to encounter one of three main wall types in your home? Below, we’ll show you how to go about fixing cracks in walls of drywall, plaster and concrete.

Wall type 1: Drywall

This is likely to be the easiest type of wall to fix.

  • You need to create a V-notch along the length of the crack. This should be 1/8 inch to 1/4 inch.
  • Use a vacuum to clean up any loose drywall in and around the crack.
  • Use mesh joint tape to cover the crack.
  • Put a thin layer of joint compound over the mesh joint tape. This should reach 2 inches wider than both edges of the tape.
  • Leave to dry.
  • Apply a second coat of joint compound. This time it should reach 6 to 7 inches on either side.
  • Allow it to dry overnight.
  • Lightly sand until smooth.


Wall type 2: Plaster

Plaster crack repair is similar to fixing drywall.

  • Get a 3/16-inch masonry bit and drill.
  • Drill holes through the plaster. Take care not to drill through the wood lath. You need to make holes every three inches along the crack.
  • Vacuum any dust or debris from the holes.
  • In each hole, spray an adhesive conditioner, following the manufacturer's instructions. Leave it to set.
  • Start at the lowest part of the wall and inject adhesive into each hole.
  • Clean up excess adhesive with a damp sponge.
  • Use your drill to attach plaster rings; always following the manufacturer's instructions. Allow it to cure.
  • Remove the plaster rings.
  • Cover the holes and crack with a layer of joint compound, and allow to dry.
  • Sand the area lightly.
  • Apply a second coat of joint compound, and allow to dry.
  • Sand the area one final time before painting or wallpapering as required.


Wall type 3: Concrete

To repair a concrete wall, you will need an epoxy repair kit to ensure you have a watertight seal.

  • Use a hammer to gently tap 3-inch finish nails partially into the crack.
  • Each nail should be 12 inches apart.
  • Mix your epoxy according to the manufacturer’s instructions. We recommend doing it on a piece of scrap wood using a putty knife.
  • This mix then need to be added to an injection port tab.
  • The injection port tab is then attached to the finish nail. There should be one tab for each nail in your crack.
  • Spread epoxy over the crack. Cover the injection port flange and at least 1 inch either side of the crack.
  • Cure for 6 - 10 hours.
  • Starting at the bottom and using a caulk gun, inject liquid concrete repair into the ports.
  • Plug the port, then move on to the next.
  • Leave to cure for a minimum of five days.
  • To finish, cut the port level with the wall. You may need to use a hacksaw.

With this simple guide, you now know how to repair cracks in plaster walls, drywall and even concrete. You should also be able to spot the signs of a more serious issue and get a professional in to help.

Key steps

  • Lookout for signs of a more serious issue requiring a professional.
  • Drywall can be fixed with mesh joint tape and joint compound.
  • Plaster crack repair needs adhesive, plaster rings and joint compound.
  • Concrete cracks need to be repaired with an epoxy mix and liquid concrete.