I would have said damp aswell because when my brother was doing up his house just after he bought it he had a similar problem on the bedroom ceiling, and that was because it was damp

Any pictures Sam?

Don't think it's damp, as one of the walls that has this problem adjoins another house (it's a terraced cottage sort of thing).

I'll see how I progress but if it starts to get ridiculous then I think I might look into using a stabiliser as Andy suggests.

Thanks guys :)

poor prep on previous coating - plaster not sealed/pva'd etc

possibliltys from my very limited exprience

Damp

Wall prepd with PVA, water based emulsion reacting with PVA as it gets wet

previous paint was applied to bare plaster with no mist coat

previous paint applied too thickly

Thing is, it's not coming off in massive sections - only small bits and at random points on each wall.

I was just worried in case I was doing something wrong with my roller :o

Should get the base completely sound before you paint over the top.

If its a massive problem you can seal the surface with a stabiliser and emulsion over the top

[Edited on 07-01-2013 by AndyKent]

Using a roller, why is it on some parts of walls in this house I am working in does part of the old paint already on the wall come off with the roller? :o

Someone had (I assumed) put some kind of a light emulsion base coat on the walls, and I have been using some Farrow & Ball paint over it.

It's pissing me off because it means I have to wait for the paint to dry, scrape off any loose but attached bits of 'old' paint on the wall, fill the area, wait for the filler to dry, and then sand down any proud bits of filler before painting over the filled area. I had thought of just stripping down all the old paint back to plaster, putting a water/B&Q cheapo white emulsion mix base coat on and then painting over that but that's gonna take a bloody long time to do as it's only me doing the work in an entire house :lol: