Rebecca Trewin
Why Plasterboard Repairs Are Worth Doing Properly
Plasterboard is wonderful stuff. It goes up fast, takes a coat of paint beautifully and gives you a lovely flat wall — until something puts a hole in it. Picture hooks pull out, door handles swing back, a shelf bracket gives way, and suddenly there's a crater staring at you from across the room. The good news is that almost every small hole in plasterboard can be repaired invisibly, and you don't need to be a plasterer to do it. You need a bit of patience, a couple of cheap materials and the willingness to sand a little more than you think is necessary.
This guide covers damage from a drawing-pin hole right up to something roughly the size of a fist. Anything bigger, or any hole where the plasterboard feels soft and crumbly, is usually a job for a full patch or a plasterer. But for the everyday knocks and scrapes of a busy British home, you can absolutely sort this yourself in an afternoon.
Gathering the Right Kit
The temptation is to reach for a tube of decorator's caulk and hope for the best. Don't — caulk shrinks, doesn't sand well and will show through paint as a dull depression. Proper filler is cheap and it behaves.
- Lightweight powdered filler — mixes with water, dries fast, sands like a dream. Ideal for the bulk of the work.
- Ready-mixed fine surface filler — for shallow dents, filling the last millimetre and fine feathering.
- Self-adhesive mesh repair patches — brilliant for holes from about 10mm to 50mm across.
- Filling knives — a 100mm one for applying and a wider 200mm one for feathering out. Using a wide knife is the single biggest secret to an invisible repair.
- Sanding block and abrasive — P120 for shaping, P180 to P220 for finishing.
- Primer — a diluted PVA solution or a dedicated plasterboard primer.
- Dust sheets, a dust mask and a vacuum — sanding filler creates very fine dust that gets everywhere.
Preparing the Damage
Preparation is where most repairs are won or lost. Start by removing anything loose. Pick away flakes of paint, torn paper facing and crumbly gypsum with a filling knife until you reach sound material. If the paper around the hole is lifting, cut it back with a craft knife rather than trying to fill over it — trapped air pockets will show as bubbles under your paint later.
For holes bigger than a nail head, undercut the edges slightly so the filler has something to grip. A gentle scrape around the rim at 45 degrees is plenty. Next, dust out the hole with a brush or a vacuum on low suction, and wipe the surrounding wall with a damp cloth.
Bare gypsum is thirsty. If you fill straight onto exposed plasterboard, the moisture gets sucked out of the filler and it sets weak and crumbly. Brush a little diluted PVA or primer into the hole and let it dry for an hour before filling. This one step makes an enormous difference to how well the repair adheres.
Filling Small Holes and Dents
For pin holes, screw holes and shallow dents, mix a small batch of lightweight filler to a smooth, thick cream. Push it firmly into the hole with the tip of your knife, working from the edges inwards to avoid trapping air. Overfill very slightly — the filler will shrink as it dries, and you want a small proud bump rather than a dimple.
Now the crucial bit: scrape the excess off flush using the wide knife held almost flat against the wall. One confident stroke, then leave it alone. Fiddling with setting filler makes it worse. Once it's touch-dry, and usually within 30 to 60 minutes, you can sand it back.
If you're filling a screw hole where the screw head is still visible, drive the screw a couple of millimetres below the surface first, then fill over it. That way it can't telegraph through the finished wall.
Using a Patch Kit for Bigger Holes
For holes up to about 50mm, a mesh patch does the job beautifully. Peel off the backing, centre it over the hole and press it firmly to the wall. The mesh is only a carrier for the filler, so it doesn't need to be perfectly flat, but it must be stuck down all round.
Apply the first coat of filler over the patch, pressing it through the mesh with a knife and spreading about 50mm beyond the edges. Don't try to get it level in one go. Let that coat dry, then build up a second and a third, each one spread a little wider than the last. Three thin coats always beat one thick one, which will crack and shrink as it cures.
If the hole is deeper than 20mm, fill it in layers and let each one dry fully — usually overnight for a thick fill. For anything larger than a fist, cut a neat square of plasterboard slightly smaller than the hole, fix it to a batten or use repair clips, and then treat the seam as a joint rather than a hole.
Sanding, Feathering and Painting
Sanding is what makes a repair disappear. Wrap P120 around a block — never use your fingers, as they create hollows — and work in gentle circles, keeping the block flat. Your aim is to blend the filler into the surrounding wall, so the transition happens over 100mm or more. Follow with P180 or P220 for a silky finish.
To check your work, hold a torch flat against the wall and shine it across the repair. Any shadow means more sanding. Run a dry hand over the area; you should feel nothing at all. Afterwards, wipe the wall with a damp cloth to remove dust.
Finally, prime the filler before painting. Filler absorbs emulsion differently from the surrounding plasterboard and paint, and an unprimed patch will show as a dull, flat ghost even after two coats. Once primed and dry, apply your topcoat with a small roller, feathering the edges into the existing paint. On matt walls this blends invisibly; on silk or eggshell, you may need to roller the whole wall to avoid a patchy sheen. It's a small extra effort — and the only person who will ever know the hole was there is you.
