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How to fill holes in walls
Filling a hole properly means choosing the right filler for its size, letting it dry fully and sanding it flat. Skipping those steps is why repairs show through paint.
Choose the filler by the size of the hole
| Hole | Filler |
|---|---|
| Nail or screw hole, hairline crack | Ready-mixed all-purpose filler |
| Dent or hole up to a few centimetres | Powder filler mixed with water, or lightweight filler |
| Fist-sized hole in plasterboard | Self-adhesive mesh patch plus joint compound or filler |
| Crack along a corner or ceiling joint | Flexible decorators' caulk |
Small holes
- Brush away dust and loose plaster with a dry brush.
- Press filler into the hole with a flexible filling knife, pulling across the hole so it fills completely. Leave it very slightly proud of the wall because filler shrinks.
- Let it dry fully. Thin fillers take an hour or two; deeper holes can take longer. The package will say.
- Sand smooth with fine sandpaper (about 120 to 180 grit) on a block. Wipe the dust away with a damp cloth.
- Prime or paint. Bare filler soaks up paint, so use a coat of primer or two coats of paint to avoid dull patches.
Deeper holes
If a hole is more than about a centimetre deep, fill in layers. Apply a layer, let it dry, then add another. Thick single layers crack and shrink. For crumbly old plaster, brush on a diluted PVA (follow the label) so the filler grips.
Holes in plasterboard
- Trim ragged edges with a utility knife.
- Stick a self-adhesive mesh patch over the hole so it is covered with at least a few centimetres of overlap.
- Spread joint compound or filler thinly over the patch and feather out the edges. Let it dry.
- Add a second, wider coat, sand lightly and finish with primer and paint.
For a very large hole, cut a neat square, fix timber battens behind the edges and screw in a new piece of plasterboard. This is an easy job for a patient beginner, but take care that there are no cables or pipes behind it; see hanging shelves safely for how to check.
Dust and old paint warning
Sanding makes dust, so wear a dust mask and open a window. In homes built before 2000, old paint, plaster or ceiling coatings may contain asbestos or lead. If you suspect either, do not sand or drill; check the HSE's guidance on asbestos before disturbing it. Contact the right professional first.
Making repairs invisible
Paint the whole wall, or at least go corner to corner, rather than a patch. Use the same paint as the rest of the wall and roll in one direction. If walls have texture, dab the filler with a sponge while it is wet to copy the pattern.
Quick fixes for common problems
If filler shrinks and cracks, the hole was too deep for one coat; fill in layers. If it flakes out, the surface was dusty or the plaster crumbly. If a patch shows through paint (called flashing), prime the filler. If a hole is surrounded by a damp patch or mould, the cause is moisture and filling will not cure it; find the leak first. Small cracks near door frames can be caused by movement; use flexible filler or caulk rather than hard filler, which will crack again.
You will need a few tools for this; see the basic toolkit.
Frequently asked questions
Why does my filled hole show through paint?
Usually because the filler was not primed, was left proud, or was not sanded flat. Prime and use two coats of paint.
How long does filler take to dry?
It depends on depth and product. Check the pack. Thin layers can dry within hours; deep fills take longer.
Can I use the same filler for wood and walls?
No. Use wood filler for wood and wall filler for plaster. Some products are all-purpose, so read the label.