Basic plasterboard repairs: cracks and holes less than 450mm
Materials you need:
• Stud cement
• Jointing plaster
• Finishing coat
• Plaster screws
• Piece of plasterboard (often referred to by the brand name Gyprock – make sure that it is the same thickness as the existing material as this will save a lot of pain)
Tools you need
• Dust mask
• Trimming knife
• Keyhole saw
• Ruler
• Broad knife (cheap plastic one will be fine)
• Sanding float with 100-200 grit sand paper
• Screwdriver (electric is preferable)
Basic plasterboard repairs: cracks and holes less than 450mm
Check the thickness of your existing plasterboard and get hold of a fresh plaster sheet of the same thickness.
Measure and cut out a new piece of plasterboard slightly larger than the damaged area. Place it over the area and trace around its edges.
Using the traced line as a guide, trim the damaged plaster back to fit the repair piece. Be careful to avoid any wiring or plumbing fixtures in the wall cavity. Use a Stanley knife to cut the facing paper and follow through with a plaster saw, or by snapping the plasterboard away from the scored side.
Make a brace for the new board by adhering diagonal pieces of plasterboard to the inside corners of the hole (use multi-purpose plaster cement) and adhere to inside of opposite wall. Allow to set, then apply adhesive to the bracing material and carefully position the new plasterboard into the gap.
How to repair big holes in plasterboard
Repairs exceeding 450mm may require additional fixings such as studs and plasterboard screws, used in combination with stud adhesive.
Cut a length of stud timber to be slightly larger than the hole and manoeuvre it into a position so that the ends are behind the existing wall. Glue into place, being careful not to get the adhesive on the face of the timber where the patch needs to go, and don’t use too much glue (just daubs 60-100mm apart). Wait for it to set.
Place fresh adhesive on the stud material and then put your plasterboard patch into place. Larger patches will need to be screwed in place. Screws and electric screwdriver are preferable to nails/clouts as the hammering required could cause damage to the opposite wall. Make sure you buy plasterboard screws – they are different to ordinary screws as they have a different head shape and are designed to screw down below the surface of the plasterboard so you can fill and sand to a perfectly smooth invisible finish.
How to repair small holes in plasterboard
Try this handy way of repairing plasterboard holes no bigger than a 100mm.
Cut your Gyprock patch as above and glue a flat and narrow strip of wood (if it’s too long you won’t be able to get it through the hole in the wall) to the back of the patch.
Wait for it to set and then put a screw through the centre from the front (the screw needs to be long enough to make a little handle on the front of your patch).
Put jointing cement around the patch edge and on the ends of the wood that will be pulled into position. Using the screw handle, manoeuvre the patch through the hole and into position and lightly pull the screw forward so that the surface of the new piece is at the same level as the wall.
Wipe away excess cement with a damp rag, wait for it to set and remove the handle screw.
Perfect plaster finish tips
Whatever size the patch, here’s what to do next.
When the patch has dried, finely sand any existing paint from the original plaster edge, making sure that no bits of the paper are loose or sticking up as if these protrude they will make it very difficult to sand.
Next, apply plaster tape along all the joins. You will have a choice of tapes – a paper tape you attach with a thin smear of plaster or an adhesive tape which is a lot easier to use as it will not slip around.
Finish the repair by using a wide knife or spatula (approximately 200mm wide) to apply two thin coats of jointing cement plus a finish coat (a much finer and softer material) over the taped join. Let it dry thoroughly between coats. At this point it is important to ensure that the first two coats must not have any lumps or bumps, as these will need to be sanded and the less sanding you do the faster you will be finished.
The first coat should overlap the join by about 100mm. Wait for it to dry and lightly sand if necessary. To achieve a seamless finish, repeat with two more layers, each time blending further away from the original join. As you are building up above the surface of your existing wall, it needs to be feathered out gradually so that you don’t see a ridge.
Once you’ve successfully tackled a minor plastering repair, you may be more confident to take on a bigger job or even trying a full DIY plastering installation.
Play down plaster imperfections by clever use of lighting and finishes
“Glancing” light (lighting installed parallel to the plaster surface, such as harsh window light or spot lighting) highlights imperfections in plaster. Minimise this effect by using evenly distributed or diffused lighting, or by installing lights which drop below rather than sitting directly on the ceiling.
Matte finishes, lighter colours and textured paints conceal minor imperfections, whereas gloss finishes tend to show up flaws.
Use a long-pile roller brush rather than a short-pile roller for a more forgiving paint finish.