Fill and sand a wall
Save £50–100 today
45 mins · Beginner · Saves £50–100 vs a decorator
Last updated: March 2025
Before you start
Filling and sanding is the most important prep work before painting. Skipping it shows through even two coats of paint.
Most holes and cracks in a wall are caused by nails, screws, minor impacts, or normal shrinkage. All of them can be fixed with the same basic technique.
Tools needed
- ✓Filling knife — a 4-inch flexible blade is ideal — you may already have one
- ✓Small bowl of water — to wet the filler before applying
- !Ready-mixed filler — buy: buy: £3–5 — Polyfilla or own-brand equivalent from any hardware shop
- !Sandpaper 120-grit and 240-grit — buy: buy: £2–4 — coarse to shape, fine to finish
- !Primer or mist coat — buy: buy: £3–8 — needed over bare filler before painting
Clean out the hole
Remove any loose plaster, dust, or old paint from inside the hole with a screwdriver tip or brush. The filler needs to bond with solid material.
Where beginners go wrong
Painting straight over filler without priming — filler is porous and shows as a dull patch through paint.
Not cleaning out the hole first — filler applied over loose material falls out within days.
Underfilling and trying to sand it flat — it is better to slightly overfill and sand back.
Stop and call a decorator if...
Cracks that keep coming back — this indicates structural movement
Cracks wider than 5mm or at window and door corners — may need specialist attention
Damp or discolouration around the crack — fix the source of moisture first
Cost breakdown
What you just learned
You now know how to prepare walls to a paint-ready standard. Filling and sanding is the skill that separates a professional-looking paint job from an amateur one.
What this unlocks
Once you can fill and sand, you are ready to paint a room properly — or tackle larger repairs like patching a hole bigger than 20mm.
✅ Completed by 3,891 people
⚠️ Watch out if you rent
Filling small nail holes when you leave is expected and helps protect your deposit. For larger holes, check your tenancy agreement — significant damage beyond fair wear and tear may be chargeable.