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Safe and sound

You know how to fix cracks in walls, of course, especially walls made of plaster. Still, read on for some great tips and the best solutions so you can keep buildings attractive, safe, and structurally sound.

Plaster wall with light damage

Everyday life in homes, commercial spaces, and industrial areas is often responsible for minor damage to plaster walls.


Having mastered how to fix cracks in plaster walls and other types helps you carry out structural and cosmetic repairs that improve the quality of buildings and prevent existing damage from worsening. Plaster walls in particular often suffer dents and minor cracks, and repairing this damage improves the appearance of these walls considerably.

Plaster walls also respond to foundation shifts and climatic changes, causing them to crack. With the right materials, you can repair even deep cracks in plaster walls to preserve their structural integrity.

Large crack in an outdoor wall

Knowing how to repair exterior wall cracks like this one is key to preventing further damage.


Whether you want to repair minor or deep cracks in plaster walls, you need a strong plaster and repair product. When selecting your product, make sure it’s formulated for the material of the wall and the depth of the crack. Also check whether it is suitable for indoor or outdoor use and the ambient conditions the wall is exposed to.

Polybit Polycrete FC is a single-component, perfect for blowholes, pores, honeycombs and more. It only requires the addition of water on site, making it easy to apply. You can apply it as a skim coat for aesthetic mortar, smoothen damaged patches, or as a fairing coat before applying protective coatings.


Looking for high industrial strength? Polybit Polycrete ST is perfect for extra reinforcement and suitable for use in both marine and industrial areas.


  • Gather materials. You need the proper filler, clean water and a mixing bucket, a mixing drill, and the appropriate float (i.e. long metal, felt, and/or Styrofoam float). Also required are different tools and materials depending on the type of substrate preparation—see step 3 and the TDS.
  • Stay safe. Wear safety glasses and protective gloves.
  • Prepare substrates. Remove all substances that impede adhesion, including dirt and low-strength layers (all anti-adhesion substances and paint layers). Check the TDS to see if your product can be applied to load-bearing substrates and whether you need to moisten your substrate prior to application. Also consult the TDS to find out when you’ll have to use a primer.
  • Mix the filler. Pour into the amount of water stated in the TDS into a mixing bucket, add the entire content of the package, and thoroughly mix them using a mixing drill until the mass is homogenous (no lumps).


To fill deeper cracks, refer to detailed method statement for the application procedure. Once this filler has dried, apply the filler with the normal consistency on top of it to smooth the surface.

  • Apply the filler. Apply and smooth the filler with a metal long float. Once the material becomes thicker, you can structure it with a felt or Styrofoam long float.
  • Let it dry. If you are going to apply additional materials on top of the filler, you need to wait for the amount of time stated in the product information.

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