When paint peels, it is a symptom of problems beneath the paint film. On areas such as windowsills, which may have open-grain wood, the cause may be air or moisture trapped under the paint film. Warmth from the sun expands the air or moisture, forcing off the paint in the process. To prevent this in future, strip off the paint to the bare wood, then use a modern microporous paint. This can 'breathe', so any moisture or air trapped beneath it will be able to escape but rain will not be able to penetrate.
If only a small area of paint has peeled and the rest is sound, rub the peeled area lightly with fine glasspaper to remove all loose material. Feather the edges of the patch as much as possible with the glasspaper. Touch up the bare surfaces with primer and when dry paint them with an undercoat that matches the surrounding colour. Then apply the top coat, blending it in with the surrounding paintwork.
A flaking ceiling in an older home usually points to the use of distemper at some time, to which emulsion won't stick. Using a paint roller, dampen the ceiling with clean water. Then scrape off the old coatings using a flexible scraper in one hand and an old dustpan in the other. Keeping the surface wet will reduce the amount of dust. When the ceiling is as clean as you can get it, seal the surface with a stabilising solution. Then repaint with emulsion.
Paint may also peel because the surface beneath it is too smooth. Clean the old glazed surface with a strong solution of sugar soap in water. Wash it off, allow it to dry and then repaint.
Another cause of peeling is dirt or grease on the surface before it was painted. Be sure to clean unpainted surfaces well, especially in kitchens, before any new paint is applied.
Peeling paint
Peeling paint