Why does paint peel and flake?
Paint doesn't fail because it's cheap. It fails because it was asked to stick to something it couldn't stick to. Find which of these seven causes you've got, and the fix becomes obvious.
Here's the principle worth internalising before anything else: paint is only as strong as what's under it. A £60 tin of the best trade emulsion on a dusty wall will peel. A budget tin on a properly prepared wall will last years. Almost every peeling problem is a preparation problem wearing a disguise.
The seven real causes
1. It was painted over a contaminated surface
Dust, grease, nicotine, hairspray, cooking residue, polish. Paint bonds to whatever's on top, and if that's a film of grease, the paint bonds to grease rather than the wall. Kitchens and rooms that were smoked in are the classic cases.
Fix: wash with sugar soap, rinse, and let it dry. Sounds tedious. Takes twenty minutes a room. Prevents the whole problem.
2. New plaster with no mist coat
Fresh plaster is porous. Full-strength emulsion has its water sucked out instantly, leaving the binder as a skin on the surface, bonded to nothing. It looks fine until something tests it.
Fix: there's no shortcut. Remove the failed paint, apply a proper mist coat, then finish. Full detail in our guide to painting new plaster.
3. It was painted over PVA
PVA seals a surface rather than letting paint key into it, and it softens when damp. Emulsion over PVA can look perfect for a year and then release in sheets. This is one of the most common legacy problems we find in Leicester houses.
Fix: the PVA has to come off. This is genuinely unpleasant work and it's the main reason a "simple" repaint sometimes isn't.
4. Moisture is getting behind it
Water arriving from behind (condensation, penetrating damp, a leak, rising damp) pushes the paint off the wall from underneath. No paint resists this, because the force is on the wrong side of the film.
Fix: find the water. Decorating over active moisture is money on fire. See our guide on mould and condensation for how to tell which you've got.
5. Painted over gloss without sanding
Nothing grips a shiny surface. Old gloss needs to be abraded to give the new coat a mechanical key, and ideally primed. Skip the sanding and the new paint sits on the old like cling film.
Fix: sand to dull the sheen, dust off, prime, then finish. Water-based paints over old oil-based gloss are especially unforgiving here.
6. The surface underneath is chalky or failing
Old distemper, weathered limewash, or very old emulsion breaks down into a powder. Paint applied on top bonds to loose dust, and takes the dust with it when it goes. Rub the wall: if your hand comes away chalky, this is you.
Fix: this is what peel stop exists for. See below.
7. Applied in the wrong conditions
Emulsion needs roughly 8–10°C and above to form its film properly. Below that, the particles never coalesce and you get a weak, powdery layer. Too hot and it skins over before it can bond. An unheated Leicester house in January is a genuine risk.
Fix: heat the room gently and let the walls come up to temperature, not just the air. Cold walls are the issue.
How to repair it properly
The most common mistake is scraping the loose bit, painting over, and finding the patch shows as a visible island. Here's the sequence that actually works:
- Scrape back to sound paint. Keep going until the scraper stops lifting material. If it keeps coming, keep going. The failed area is always bigger than the visible one.
- Feather the edges. This is the step everyone skips. Sand the boundary between bare wall and remaining paint until you can't feel the step with your fingertips. Unfeathered edges telegraph straight through the new finish as a ridge, forever.
- Treat the cause. Wash off grease, fix the leak, sand the gloss. Otherwise you're scheduling a repeat.
- Fill and sand any damage. Scraping usually takes some substrate with it.
- Stabilise or prime the exposed area. Mist coat on bare plaster, peel stop on chalky surfaces, primer on wood.
- Two full coats across the whole wall. Not just the patch. Spot-painting a wall leaves a permanent difference in sheen that's obvious in daylight.
What peel stop actually does
Peel stop is a penetrating binding primer. Where a normal primer sits on a surface, peel stop soaks into a chalky, powdery or marginally sound one and glues the loose particles together from within, leaving a stable film that new paint can safely bond to.
It's the right answer when a surface is weak but not failed: old chalky emulsion, feathered edges around a repair, historic surfaces where taking everything back to bare plaster would be destructive or absurdly expensive.
It's the wrong answer when paint is actively lifting in sheets, or when moisture is the cause. It binds powder; it doesn't glue down a flake that's already let go, and it can't stop water. Anyone applying peel stop over active damp is wasting your money.
In our instant quote it appears as a clearly priced line with an explanation, so you can see what it is and what it costs rather than finding it buried in a lump sum.
Why bathrooms are the worst offenders
Bathrooms stack three of the seven causes at once: steam condensing on cold surfaces (cause 4), temperature swinging 15 degrees twice a day, and frequently a non-breathable finish trapping moisture in the wall. Add a shower room with no working extractor and paint has no chance.
The fix is nearly always ventilation before paint. An extractor that runs on for 20 minutes after the shower does more for your bathroom paintwork than any product you can buy.
When patching isn't worth it
Be honest with yourself if you find: peeling across more than roughly a third of a wall; multiple layers letting go at different depths; PVA underneath; or anything still damp. At that point patch repairs are a false economy. You'll chase failures around the room for months.
Stripping back and starting properly costs more on day one and less over five years. That's the whole calculation, and it's the same one behind our guide to how long paintwork should last.
Peeling paint you want sorted properly?
Full prep priced and itemised, so you can see exactly what you're paying for.
See My Price Instantly →Frequently asked questions
Why is my paint peeling off the wall?
Peeling almost always means the paint never bonded properly to what was underneath. The most common causes are painting over a dirty or greasy surface, painting new plaster without a mist coat, painting over PVA, moisture behind the paint, painting over a glossy surface without sanding, or applying paint in unsuitable temperatures. The paint is rarely the problem; the surface it was put on usually is.
Can you just paint over peeling paint?
No. New paint is only as sound as the layer beneath it. If you paint over flaking paint, the new coat bonds to a layer that's already letting go and it will come away with it, usually taking a bigger patch than before. The loose material must be removed back to a sound edge first.
How do you fix peeling paint properly?
Scrape back to firmly adhered paint, feather the edges by sanding so the transition is invisible, treat the underlying cause, fill any damage, prime or stabilise the exposed surface, then repaint. Skipping the feathering step is why repairs often show as a visible ridge under the new paint.
What is peel stop and what does it do?
Peel stop is a penetrating binding primer. It soaks into chalky, powdery or marginally sound surfaces and binds them together, then provides a stable base for new paint. It's used where the substrate is weak but not failed, and where scraping everything back to bare plaster would be impractical or damaging.
Why does paint peel in the bathroom?
Bathrooms combine three problems: steam, temperature swings and often a non-breathable finish. Moisture condenses on the surface and gets behind the paint film, breaking the bond from underneath. Poor extraction makes it worse. Fixing extraction matters more than changing paint.