Hi I live in an old house in the country subject to very damp weather. The walls are solid and, in some areas, suffer from dampness. At some stage in the future I will dry-line the walls to solve this problem but, at the moment I have to paint them. The walls are plastered and, a short while after painting, damp patches start to show through the paint with mould showing through. Is there any way I can pre-treat the walls to prevent this growth of mould and improve the life of the paint as, in some cases, the walls have to be painted twice a year improve appearances. I had thought of treati