I moved into my current house two and a half years ago. It was used as a Casa Rural prior to this and was beautifully decorated throughout. Over the past 6 months the paint on the interior walls has started to peel off in great sheets leaving piles of chalk-like dust on the floors. I tried painting over the chalky substance but the paint just soaked in and dried a completely different shade. Honestly, it is as if plaster of Paris was used to skim the walls prior to painting. This morning I found that a great sheet of paint had fallen off in my dining room - about 60cm x 40cm and enough 'chalk' to reline the centre court at Wimbledon! Why does this happen? Is there some sort of sealant I can use before I repaint - if so what is it called? All of the interior and exterior paint on sale here seems to be a plastic variety and does not last very long. Come back Dulux I say. Any information and advice would be most welcome. Thank you.

There is a sealant you can use, yes ... but I'm not sure that will fix your problem ... I use Sikoseal.
Are the walls damp? Is it a very old house?

Thanks, the walls are not damp and the house was re-built 26 years ago. We have had only 2 days of rain over the past 10 weeks and not sufficient to penetrate the marble cladding on the outside of the house at the spot where last nights damage to the dining room happened.

It's all very confusing.

We get a lot of blistering problems where people have used more modern paint over lime wash.

The only real solution we found is to scrape the wall as clean as poss, but it's backbreaking work.

I live in a very old village house and I have to touch up the walls every year. First I have to brush them down,getting a ton of chalk in the process,then re-paint where needed. It is worse than the Forth Bridge but it looks nice for about eight months. Good luck.

You could try using PVA adhesive, mixed with water it prevents dusting on cement floors, it is sold as "cola blanca" out here, get it from any ferreteria or Leroy Merlin, it is cheap so worth a try.

Thanks very much everyone. I will give your ideas a try - one in each room and see what is best for me. I might leave it until the Winter sets in as it is far too hot at the moment to even think about physical work.

Unibond do a sealing product which worked for me when I had grease marks on a wall which continually seeped through a painted wall

I know the feeling, paint falls off and black mold inside when it rains.

good tip for the black mould,,,,,an old paint-brush and some bleach...just wipe the brush over the area and the mould goes. doesn't come back for a while either. just don't get it in your eyes. it stings. and other regions are painful too.

Yeah, I usually hoover most of it off first.

re bleach to fix mould, i have found that swimming pool chlorine, the "four effect" type is very good for this as it contains anti algea and anti fungicide

My tip would be to check out the wall first - if it's not using lime then I would take off all the old render and put on new.

Use a strong render (sand, cement mix but known here as 'material) impregnated with SIKA Top Coat.

It may be that the outside marble has stopped the wall breathing and sealing the inside may make matters worse. Try speaking to a Spanish builder for advice as Uk techniques may do more harm than good.

Hi John

I have played around with old buildings for years. Although I'm by no means an expert it seems your house may have been "beautifully decorated" Just before youy bought it, with a plastic (non breathable) paint over a yeso or lime render.
If a building has no damp proof course, i.e is old like yours, it may not normally be damp because of a natural wicking-up and drying out that happens in warmer countries like Spain. But I think everyone will agree we had an English winter this year! which caused loads of problems to houses where the greater than average amounts of water and the salts in it crept up the walls internally but stayed inside the plastic paints, effectively blowing the paint and plaster off the wall. Painting again, either externally or internally with non-porous paint or waterproof treatment is not the answer.
Your house is old. I guess you love old buildings and that's why you bought it . Now you'll need to treat it with respect.

The 'rule' is to treat like with like. It may cost more but use lime based paints on lime or yeso render. They may be more difficult to find in Spain these days. Also don't even consider removing the lime based render and replacing it with cement! It won't work and will eventually break off the 'soft' construction.