I have spent several months doing up a cellar the floor of which is approx 3 feet below ground level the floor also having been layered with a bitument type material some 12 years + ago. It is fairly dry with heating and carpets down there but I now have some patches where the paint on the walls is bubbling. In doing up the cellar I wire brushed the brick walls to remove some white stuff (fungus / mould?) and then plastered /painted the walls. They seemed reasonably dry but now in retrospect maybe they weren't. This bubbling is only happening in small areas at the bottom of the walls. Any ideas on whay could be causing the bubbling and how to treat it? Would some sort of sealant or antifungal substance be ok or is it more likely damp is coming through from outside. The bubbling also occurs on internal cellar walls, not just those with outside contact.