How do I fix a hole in a plasterboard wall?

The repair depends entirely on size, because plasterboard has no strength in the middle of a hole. The common failure is filling a large hole with filler, which cracks and falls out within months because nothing supports it.

Safety

What you'll need

• Filler
• Filling knife
• Sandpaper
• Mesh patch (optional)
• Offcut of plasterboard (optional)
• Timber batten (optional)
• Jointing tape (optional)

Step by step

1. Check what is behind before cutting anything.A cable detector, and think about what is on the other side. Near a socket or switch, assume cables.
2. For small holes, just fill.Under about 2cm — screw holes, small dents. Rake out any loose material, fill slightly proud, let it dry, sand flush. Two thin coats beat one thick one.
3. For medium holes, use a mesh patch.Up to about 10cm. A self-adhesive aluminium mesh patch over the hole, then filler skimmed over it in two or three thin coats, feathered well out.
4. For large holes, cut a proper patch.Square the hole up with a knife so the edges are straight and sound. Cut a plasterboard offcut to fit.
5. Add battens behind for support.The step people skip. Slide a length of timber through the hole so it spans behind, and screw through the existing board into it at each end. Now there is something to fix the patch to.
6. Screw the patch to the battens.Slightly recessed, not proud. Drywall screws just below the surface so the filler can cover them.
7. Tape and fill the joints.Jointing tape or scrim over every join, then filler in thin coats, each wider than the last. Feathering the edges out is what makes it invisible.
8. Sand, prime and paint.Sand smooth with fine paper, then prime the repair — bare filler absorbs paint differently and shows through as a patch otherwise.

Tips

• Three thin coats of filler beat one thick one every time. Thick filler cracks as it dries and shrinks.
• Feather the filler much wider than feels necessary — 30cm or more for a large patch. A visible edge is what gives a repair away.
• Prime before painting. Skipping this is why repairs show through as a different sheen even when the shape is perfect.

Common mistakes

• Filling a large hole with filler alone — Nothing supports it. It cracks and falls out within months. Anything over about 10cm needs a backed patch.
• Not priming the repair — Filler absorbs paint differently from the surrounding wall, so the patch shows as a dull area even after painting.

Questions people ask