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How to fix cracks in plaster walls

Freshly painted beige wall with a smooth, clean finish and no visible cracks or imperfections.

Overview

Over time, plaster walls can develop cracks due to movement, temperature changes, or general wear and tear. Fixing these cracks is a straightforward D.I.Y. project that will give your walls a smooth, fresh finish.

Safety tip: Always wear the appropriate safety equipment (safety glasses, gloves, ear muffs and a mask, for example) and always follow the instructions for the product or equipment.

Steps

1Prepare the crack

Start by using a utility knife to slightly widen the crack and remove any loose or flaky plaster. This step ensures the plaster filler adheres properly and creates a strong repair. Once the crack is widened and any debris is cleared, take a damp sponge or cloth and wipe down the area to remove dust.

This will help the filler bond smoothly with the plaster.

A person wearing gloves is using a utility knife to widen a crack in a wall, preparing it for repair

2Apply the filler

Using a putty knife, apply the plaster filler into the crack, pressing it in firmly to ensure the entire crack is filled. Smooth it over the surface, removing any excess so that it sits flush with the wall. If the crack is deep, apply the plaster filler in layers, allowing each layer to dry completely before adding the next. This prevents shrinking or cracking as the filler dries. Leave the filler to dry according to the manufacturer's instructions before moving on to the next step.
A person is using a putty knife to apply filler to a wall crack for repair.

3Apply a second coat of filler

For a seamless finish, apply a thin second coat of plaster filler over the repaired area. Use a putty knife to spread it evenly, feathering out the edges so it blends into the surrounding wall. Allow the second coat to dry completely before proceeding.
A person wearing black gloves is applying a second coat of filler with a putty knife to cover a repaired crack on a wall.

4Sand and clean the surface

Once the filler is completely dry, lightly sand the area with fine-grit sandpaper to remove any bumps or ridges. This will create a smooth, even surface that blends seamlessly with the rest of the wall. After sanding, wipe the area down with a damp cloth to remove any dust and ensure a clean surface for painting.
A person wearing a mask and gloves is sanding a patched crack on a wall to remove any bumps or ridges near a window.

5Prime and paint

Apply a coat of primer over the repaired area to help the paint adhere evenly and blend with the surrounding wall. Once the primer is dry, use a paintbrush or paint roller to apply paint in the same colour as your wall. For the best results, apply two coats of paint, allowing the first coat to dry completely before adding the second.

If the crack keeps reappearing, consider using a flexible filler to allow for movement. Always check the drying times on the product packaging to ensure a strong, long-lasting repair. If you're not painting an entire wall, feather the new paint out slightly to blend with the existing colour.

A person wearing gloves is using a small paint roller to apply primer and paint over the repaired area

6Looking for more D.I.Y. projects?

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Health & Safety

Asbestos, lead-based paints and copper chromium arsenic (CCA) treated timber are health hazards you need to look out for when renovating older homes. These substances can easily be disturbed when renovating and exposure to them can cause a range of life-threatening diseases and conditions including cancer. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer or visit our Health & Safety page.

When following our advice in our D.I.Y. videos, make sure you use all equipment, including PPE, safely by following the manufacturer’s instructions. Check that the equipment is suitable for the task and that PPE fits properly. If you are unsure, hire an expert to do the job or talk to a Bunnings Team Member.