Hi DIY Guy & Verne. Thanks for your replies. The house I live in is very old. I live in Ireland where the climate is wet and cold, not just in Winter. The walls are made of rendered stone and there is no damp course. I ventilate the house as often as possible and I have dehumidifiers going throughout the house 24/7; thats the hand I am playing with at the moment. Your comments regarding dry-lining are well noted and, when I start to gut each room and dry-line, I will need a system that will account for the points you have raised; some practical way of ventilating the wall behind the dry-lining, for instance. I, unfortunately, do not have the time to do this at present. I had intended to raise another thread on this at a later stage, but if you have any suggestions I would appreciate them. In the meantime I still have to paint these walls and any other practical suggestions would be greatly appreciated.