You are better off treating the cause of the problem. Other wise it will just come back through. If it's on the front and rear elevations' high up near the ceiling it could be a gutter problem. If it's near a chimney breast wall it could be a flashing or roof problem. If its near a window it could be its not sealed properly. Also if you dry washing on radiators etc it could be spot mould, you can buy a quality spot mould cleaner. Then look at ventilating your rooms. Also check if you have had cavity wall insulation fitted .
Thanks Michael
. Rino joinery & maintenance
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Hi there
If your walls are coated with a paint that is stopping the plaster breathing then it could be worth skimming over then painting with a non vinyl paint or a paint made for anti condensation found at your local paint specialist you may need to google for this info,other than this you are looking at thermal boards stuck on the walls then a skim.
Regards
Joseph