Why is my paint peeling or bubbling, and how is it fixed?

Is it peeling, blistering or flaking?

They look similar but point to different problems, so it helps to know which one you've got.

• Blistering or bubbling: raised bubbles in the paint film. Pop one: water inside points to moisture; a dry bubble often points to heat or trapped solvent.
• Peeling: the paint lets go in strips or sheets, often from bare timber or an old glossy coat. It usually means the paint never bonded well, or moisture pushed it off.
• Flaking and cracking: small brittle pieces lifting, often on older paint that has aged and lost its flexibility.
• White powder on brick or render: that's usually efflorescence, salts carried out by moisture, not failed paint.

Is moisture the most common cause?

Very often, yes. Dulux's trade advice on peeling lists moisture getting in through uncaulked joints, worn caulking, and roof or wall leaks as common causes, along with poor preparation and lower-quality paint.

Its advice on blistering adds that bare timber above 15 per cent moisture content is unsuitable for painting. Timber that has been rained on, sits in shade, or is close to garden beds and sprinklers can hold far more water than it looks. Paint it too soon and the moisture tries to escape when the sun heats the wall, lifting the paint as it goes.

Inside the house the usual suspects are bathrooms and laundries without enough ventilation, a slow leak from a shower or roof, and rising damp at the bottom of masonry walls. Peeling bathroom ceilings are so common we've written a separate guide on mould and paint on bathroom ceilings.

Can poor preparation make paint peel?

Yes, and it's the cause you can't see until it's too late. New paint is only as good as what it's stuck to. Common prep failures include:

• Painting over dirt, grease or chalky old paint without washing it off first.
• Painting over a hard, glossy coat without sanding it dull or using an adhesion primer. Taubmans' technical advice recommends an adhesion primer on glossy surfaces.
• Leaving loose paint in place and painting over the top, so the new coat peels off with the old.
• Skipping primer on bare timber or patched areas.

How do you check whether old paint is sound?

Dulux's Weathershield datasheet describes a simple adhesion test. Cut an X through a clean area of the paint with a sharp knife, press sticky tape firmly over the cut, then rip it off. If old paint comes away on the tape, it needs to be removed before repainting.

The same datasheet warns that paint which looks sound can still lose adhesion when it's recoated, particularly if the new colour is darker. That's why testing matters before a colour change, not just when paint is visibly flaking. Old glossy trims are a special case: see our guide to painting over oil-based doors and trims.

Can the weather on painting day cause bubbles?

It can. Haymes lists bubbling as a risk when paint is applied above 32°C or when it's too cold, on humid days, or when fresh paint gets wet soon after it dries, and it advises against painting in direct sunlight. A wall in full summer sun can be far hotter than the air temperature, so the paint skins over before it has properly flowed and bonded.

Good painters follow the shade around the house, avoid starting outside work when rain or heavy dew is due, and stop early enough in the day for the paint to dry. Our guide to the best time of year to paint outside covers the temperature limits paint makers give.

What about white powder on brick and render?

That's efflorescence. Dulux's trade advice describes it as white salts, mainly calcium carbonate, brought to the surface by moisture moving through masonry. Mild cases can be dry-brushed and then treated with a 5 per cent white vinegar solution, but it will keep coming back until the moisture source is dealt with. New render and concrete also need time to cure before painting; Dulux gives 28 to 30 days.

How is peeling paint fixed properly?

The order matters more than the paint brand.

• Find and fix the cause first: seal gaps, replace failed caulking, repair leaks, improve ventilation.
• Let the surface dry out properly. Timber and masonry that have been wet for a long time can take a while.
• Scrape and sand all loose paint back to a firm edge, and feather the edges so they don't show through.
• Wash off dirt, chalk and mould, and let it dry.
• Prime bare timber and patched areas with a primer suited to the surface.
• Apply the topcoats in the right conditions, following the product's temperature and recoat instructions.

Is sanding old flaking paint safe?

Take care with older homes. Paint in houses built before 1970 can contain lead, and dry scraping or sanding it creates harmful dust. Test before you start. Our guide to repainting old weatherboards explains the safer methods.

If a patch of peeling paint is part of a bigger problem, or you'd rather someone else found the cause, we can look at it when we quote an exterior repaint. We fill and sand properly and prime where it's needed, and the written quote says what prep your house needs.

Quick questions

Sources

What this guide relies on. Product advice changes, so check the maker's current instructions for the exact paint you're using.

1. Peeling: professional painter problem solver — Dulux Trade
2. Blistering of exterior decorative paints — Dulux Trade
3. Efflorescence — Dulux Trade
4. How to stop paint cracking, flaking, blistering and bubbling — Haymes Paint
5. Weathershield Low Sheen technical datasheet (surface preparation) — Dulux