The essentials in 30 seconds
To paint a wall, start with the surface: fill holes and cracks, sand the repairs smooth and clean off dust and grease. Move furniture, lay dust sheets and run painter's tape along skirting boards, frames and the ceiling line. Cut in first: paint the edges and corners with a 2-inch or angled brush, loading only about half of the bristles. Then roll the main area in W-shaped strokes, section by section, overlapping while the paint is still wet so the joins disappear. Valspar says two coats are generally recommended; wait the recoat time on the tin between them. Pull the tape while the last coat is still wet or tacky. Behind a radiator, switch the heating off, let it go cold, use a long-reach radiator roller and wait at least 24 hours before turning it back on.
- New bare plaster needs sealing first; follow your paint's instructions.
- In a pre-1978 home (U.S.) or with paint from before the 1960s (UK), check for lead before sanding.
What you need to paint a wall
- Wall paint suited to the room: Valspar suggests a kitchen and bathroom paint where there is more moisture.
- Roller and tray, with an extension pole for high areas.
- Brush: a 2-inch brush or angled cutting-in brush.
- Painter's tape and dust sheets (drop cloths).
- Filler, sandpaper and a sponge or cloth.
- Primer or undercoat if needed: for new bare plaster, stains or a big colour change.
| Roller | Pile | Best for |
|---|---|---|
| Short pile | 6–8 mm | Smooth walls, including drywall |
| Medium pile | 10–12 mm | Lightly textured walls and ceilings; holds more paint |
| Long pile | 20–32 mm | Heavily textured walls, concrete, outdoor walls |
| Foam | — | Gloss or varnish |
| Radiator roller | — | Behind radiators and awkward gaps |
Getting the wall ready
-
01
Fill
Fill holes and cracks with a suitable wall filler and let it dry as the maker says. For larger damage, see our drywall repair guide.
-
02
Sand
Sand the filled areas smooth, plus any rough patches, and remove all the dust.
-
03
Clean
The wall must be clean, dry and free from dust, dirt and grease. Let it dry fully.
-
04
Prime if needed
Valspar says new bare plaster must be sealed with a primer and undercoat; it also helps with dark or vivid colours. Allow at least 2–4 hours before painting, or as your product says.
-
05
Protect the room
Move furniture to the middle and cover it, cover the floor, take down pictures and shelves, and remove switch and socket plates where appropriate. Tape skirting boards, frames and the ceiling line.
If the wall has mould, deal with the cause first: see black mould on walls.
What to paint first in a room
Dulux's order is ceiling first, then walls, then windows and doors, and finally skirting boards. On each wall, cut in from top to bottom, then roll the main area.
Cutting in with a brush
Cutting in means painting the strip a roller can't reach: where the wall meets the ceiling, the corners, the skirting boards and the door and window frames. Load about half the brush, remove the excess and work carefully along the edge to make a neat border. Valspar US advises cutting in one wall at a time, so you can roll the rest while the cut-in paint is still wet; that avoids a visible frame around the wall.
How to paint a wall with a roller
-
01
Prepare the roller
Stir the paint well. On a new pile roller, Valspar UK suggests dipping it in water and letting it dry first to remove loose fluff.
-
02
Load it evenly
Roll it through the paint, then over the ridged part of the tray so it is evenly coated but not dripping.
-
03
W strokes
Work on one manageable section at a time, in W-shaped movements, then fill in the gaps. Don't press hard: let the roller do the work.
-
04
Keep a wet edge
Roll towards the section you just finished, overlapping while it is still wet. Stopping and restarting on dry paint causes lines, which Valspar calls lapping.
-
05
Don't overwork
Going over the same spot again and again thins the paint, causes spatter and roller marks, and can pull fresh paint off.
-
06
Smooth out
Lightly roll back over the section to remove roller lines.
How many coats of paint on an interior wall?
Valspar UK says two coats are generally recommended for an even finish. Let the first dry for the recoat time on the tin, check for flaws, sand lightly and dust if needed, then apply the second the same way. To estimate paint, Valspar US says one gallon generally covers up to 400 sq ft with one coat; if you need more than one tin, mix them in a large bucket so the colour is even. Remove the painter's tape while the last coat is still slightly wet or tacky, so it doesn't lift dried paint, and let everything dry before moving furniture back.
How to paint behind a radiator without taking it off
-
01
Heating off
Turn the radiator off and wait until it is cold to the touch. Paint on a warm surface dries too fast, which can cause blistering, cracking and poor adhesion (Screwfix).
-
02
Clean behind it
Remove dust and cobwebs with a duster or a vacuum nozzle, then wipe the wall with a damp cloth wrapped round a long tool.
-
03
Protect
Tape the skirting board below and the radiator edges and valves, or cover the radiator.
-
04
Cut in
With an angled brush, paint along the top, sides and bottom near the skirting, without forcing the brush into tight gaps.
-
05
Long-reach roller
Load a slim radiator roller lightly. Slide it down behind the radiator and roll from the top down, then from the bottom up, to catch areas behind the brackets.
-
06
Check
Use a torch to find missed patches and touch them up while the paint is still wet.
-
07
Second coat and drying
When the first coat is dry, repeat. Toolstation and Harris advise waiting at least 24 hours before turning the heating back on, or as long as the paint maker says.
Screwfix, Toolstation and Harris don't give separate steps for towel or column radiators: the same approach applies wherever a long-handled radiator brush or slim roller fits behind. If paint gets on the radiator, wipe it off straight away; painting the radiator itself needs a heat-resistant radiator paint.
Why the finish looks patchy
- Cutting in the whole room first and rolling later: the edges dry and show as a frame.
- Overloading the roller or brush: drips and splatter.
- Rolling over drying paint: lap marks.
- Pulling dry tape: torn edges.
- Painting over dust or grease: poor adhesion.
- Turning the heating on too soon after painting behind a radiator: bubbling and streaks.
Lead paint: what to do before sanding
- U.S.: homes built before 1978 may contain lead-based paint; EPA recommends a certified lead inspector or risk assessor to test the surfaces. If you can't tell the age of the home, assume lead and use EPA's lead-safe DIY practices: contain the area, cover floors with plastic, protect yourself, minimize dust and clean up carefully. Anyone paid to disturb paint in a pre-1978 home must be lead-safe certified.
- UK: the BCF advises testing if the house is over 40 years old, with a professional decorator, a test kit or a laboratory. Don't remove sound paint: overcoating is the safest option. If preparation is needed, rub down wet with waterproof abrasive paper; never dry sand, burn off or use a blowlamp, and keep bystanders out.
How to paint a wall: FAQs
How do you paint a wall properly?
Fill, sand and clean, tape the edges, cut in with a brush, roll in W strokes while keeping a wet edge, apply two coats and remove the tape while the paint is still wet.
Do you cut in or roll first?
Cut in first, one wall at a time, so you roll the rest while the edges are still wet.
How many coats of paint does an interior wall need?
Valspar says two coats are generally recommended, waiting the recoat time on the tin between them.
How do you paint behind a radiator without removing it?
Turn the heating off and let it cool, clean and tape, cut in with an angled brush, then use a long-reach radiator roller from the top down and the bottom up; wait at least 24 hours before switching it on.
Can I paint a wall with just a brush?
Yes, but Valspar uses the brush for edges and corners; a roller holds more paint and covers large areas at a time.
Sources
Paint and tool makers' instructions and government and industry guidance, checked on 3 November 2026 (03/11/2026).
- Valspar UK · How to paint a wall ↗Tools; fill, sand, clean; primer and undercoat for bare plaster, 2–4 hours; protect the room; cutting in with a 2-inch brush, half loaded; loading the roller; W strokes; overlap while wet; avoid roller marks; two coats; tape off while wet or tacky. Read.
- Valspar UK · How to use a paint roller ↗Pile sizes 6–8, 10–12, 20–32 mm; foam and radiator rollers; remove fluff; W pattern; don't overwork; paint towards the finished patch. Read.
- Valspar US · Interior painting basics ↗One gallon up to 400 sq ft per coat; mix tins; angled brush; one wall at a time while cut-in is wet; W pattern; wet edge and lapping; remove tape while wet. Read.
- Dulux UK · What order to paint a room in ↗Ceilings, walls, windows and doors, skirting; cut in top to bottom; long-handled mini roller behind radiators. Read.
- Screwfix · How to paint behind a radiator ↗Heating off and cold; cleaning; masking valves; cut in; load radiator roller lightly; top down, bottom up; torch check; removal means draining and disconnecting; shadows with colour change; dry before heating on. Read.
- Toolstation · How to paint behind a radiator ↗Tools; steps; second coat; wait at least 24 hours before turning the radiator back on. Read.
- Harris · How to paint behind a radiator without taking it off ↗Turn off and cool; clean; long-handled radiator brushes and mini rollers; don't overload; check with a torch; wait 24 hours; heat-resistant paint for the radiator itself. Read.
- U.S. EPA · Lead-safe renovations for DIYers ↗Pre-1978 homes; certified inspector or risk assessor; assume lead if unknown; set up, protect, minimize dust, clean up; RRP rule for paid work. Read.
- U.S. EPA · Reduce the risk of lead exposure at home ↗Homes before 1978 more likely to have lead-based paint; renovation creates lead dust. Read.
- British Coatings Federation · Lead in painted surfaces, guide for the general public (PDF, HS 032, December 2015) ↗Lead out of most paints in the 1960s; test houses over 40 years old; overcoat sound paint; wet abrasion; no dry sanding or burning; professional decorators and test kits. PDF read.
Ready to paint?
Prepare the wall, cut in one wall at a time, roll in W strokes while the edges are wet, and give it two coats.