Before you get started
If you need to enlarge a hole, be careful not to cut through any hidden supply cables or pipes that may be buried. Use a cable, pipe and stud detector to help you here.
Small and large holes, whether on ceilings or walls, can be patched with plasterboard offcuts.
The thickness of plasterboard varies. Normally it is either 9.5mm or 12.5mm thick. When patching a hole, try to get the right thickness, but if in doubt use the thinner option as you can always build up the plaster level to the surrounding area.
Flaky or missing plaster on a wall or ceiling is easily fixed. For shallow holes, one-coat plaster can be used; for deeper holes, build up layers. Use undercoat plaster on a semi-porous surface and bonding coat on a non-porous surface to provide a base in deep holes. This may be finished with a skimming or finishing plaster.
If old plaster is unstable in a number of areas on a masonry wall it may be necessary to remove all the old plaster. You will need to render and then plaster the wall from scratch.
Most loose plaster can be easily removed, but you may need to use a club hammer and bolster chisel on more difficult areas.
Ready-mixed and mix-your-own plaster can be bought. Readymixed is more expensive, but is a perfect mix. For mix-yourown, follow the manufacturer's guidelines to get the right consistency.
Never use out-of-date plaster. It generally hardens quickly, making it impossible to smooth in place.
Use a paint brush to brush off any loose debris from the damaged area. Pay particular attention to the edges. Ensure area is as dust free as possible.
Bond new plaster to old by brushing the area, and some surrounding wall, with a 5:1 PVA solution – five parts water to one part PVA.
Apply some ready-mixed, one-coat plaster to the hole. Do not put too much plaster on the plastering trowel, but press it firmly in place.
Smooth the plaster roughly level with the surrounding wall surface and leave for half an hour, or until it starts to go off/set.
Smooth the area once more, trying to get as smooth a finish as possible, which is level with the surrounding wall surface. Sand when dry.
Repair a large hole in a stud wall or ceiling
Use a cable, pipe and stud detector around the work area to find cables and pipes to help check that it is safe to cut though the plasterboard.
Locate the studs on either side of the damaged area by feeling into the hole or using a stud detector. Measure distance to studs.
Draw vertical lines with a spirit level to mark the centre of each stud, extending the lines above and below the damaged area.
Use the spirit level once again to mark horizontal lines to join the verticals, making a rectangle around the damaged area.
Cut away the rectangular area of wall with a drywall saw and a retractable knife and remove the damaged section of plasterboard.
Attach noggings (horizontal wood supports) to the studs, one above and one below the hole, to make fixing points for the screws.
Measure and cut a section of plasterboard to fit the hole snugly and fix it to the studs and noggings with drywall screws.
Fix the edges of the original plasterboard to the studs and noggings in just the same way, using drywall screws.
When all is secured, carefully tape along each of the edges of the rectangle with plasterboard jointing tape, going right up to and over the corners.
Plaster the surface of the repaired wall with finishing plaster, ensuring you cover all of the scrim. Allow to dry and sand until it is smooth.
Repair a small hole in a stud wall or ceiling
Repairing a small hole requires a slightly different technique. Draw a rectangle around the damaged area with the help of a spirit level.
Check for cables and pipes before cutting away the rectangular damaged wall section with a drywall saw and a retractable knife.
To make fixing points, thread batten in through the hole, behind the top and bottom edges. Hold in place with fingers and fix in place.
Measure and cut a small rectangular section of plasterboard to fit the hole snugly and fix it to the battens with drywall screws.
Apply some filler, ensuring you cover all screwheads. When dry, sand the area until it is smooth. You may need a second coat.