BeginnerAbout 45 min
Inspect, clean, fill, sand, remove dust and mask — and know when to stop and call a specialist.
What you'll achieve
Sound, clean, smooth surfaces ready for primer or paint — the most important stage for a lasting finish.
Suitable surfaces and conditions
Previously painted walls, ceilings and woodwork in sound condition. New plaster needs to be fully dry first (follow the plasterer's and paint maker's guidance).
Tools and materials
- Sugar soap or a suitable cleaner, sponges, buckets
- Scraper, filling knife, filler (fine surface filler and/or flexible caulk)
- Sanding block and paper, or dust-extracted sander
- Vacuum and tack cloth or damp microfibre
- Dust sheets, masking tape
- PPE: glasses, FFP2/FFP3 mask, gloves
Preparation checklist
- Clear the room or move furniture to the centre and cover it.
- Lay dust sheets and protect flooring along skirting.
- Turn off electricity at the consumer unit before loosening socket and switch faceplates, or mask them instead.
Safety precautions
- STOP if you find suspected asbestos (old textured coatings, some ceiling tiles) — do not disturb; arrange testing by a competent person.
- STOP before sanding or scraping old paint that may contain lead — test first and follow GOV.UK guidance; never burn it off.
- Significant mould or persistent damp needs the cause fixed by a specialist; don't just paint over it.
- Wear an FFP2/FFP3 mask when sanding and use dust extraction where you can.
Step by step
- Inspect every surface in raking light (torch held flat to the wall) and mark defects with low-tack tape or pencil.
- Wash surfaces with sugar soap solution, working from bottom to top to avoid streaks, then rinse with clean water. Allow to dry.
- Scrape away loose and flaking paint back to a firm edge.
- Fill holes and cracks with filler, slightly overfilling. Deep holes may need filling in layers.
- Run flexible caulk along gaps between woodwork and walls, and smooth with a damp finger.
- When filler is fully dry, sand it flush. Lightly sand glossy paint to give a key.
- Feather the edges of chipped paint so they won't show through.
- Remove all dust: vacuum, then wipe with a damp cloth or tack cloth.
- Spot-prime bare filler, wood or metal as the products require (Lesson 4).
- Mask only what needs protecting, pressing tape edges firmly.
Common mistakes and how to avoid them
- Painting over dirt or grease — the paint won't stick.
- Sanding filler before it's dry — it tears and leaves dips.
- Leaving dust on surfaces — causes gritty finish.
- Using caulk to fill holes in flat surfaces — it shrinks and stays flexible; use filler.
Troubleshooting
- Filler shrank: apply a second thin skim and re-sand.
- Cracks keep reappearing: they may be structural movement — note for the customer.
- Stains bleed after washing: use a stain blocker (Lesson 4).
Final quality check
- Surfaces clean, dry and dust-free
- Filler flush and smooth under raking light
- Gaps caulked
- Hazards reported, not disturbed
Cleaning and storage
Clean filling knives immediately before filler hardens. Bag sanding dust carefully; don't sweep dry dust into the air.
Always follow the manufacturer's instructions and technical data sheet — they take precedence over general guidance here. This is educational guidance only, not a qualification or certificate.