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How to repair cracks in plaster

Person scraping crack with putty knife.

Overview

Plaster walls can crack from time to time. We'll show you how to plaster over a crack properly. You will learn how to prepare a crack before you plaster, and the best way to reinforce new plaster with jointing tape.

Steps

1Prepare the surface of the plaster crack

Scrape in the crack with your putty knife to open it up a little and give the plaster a bit more surface to stick to. Then sand around the crack to roughen up the paintwork. Now dust the surface down with a rag and cover the crack with a piece of jointing tape.
Person scraping crack with putty knife.

2Cover the crack with plaster compound

Scrape the plaster compound into the crack and flatten it on to the wall with your paint scraper. Once the compound is dry, lightly sand it until it is smooth. Dust the wall off and apply a second, slightly wider coat of plaster compound to the wall. Again, let the compound dry, sand it smooth and dust it down. Now the crack is repaired and your wall is ready for painting.
Person using paint scraper to apply plaster to wall.
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.