DIY Doctor UK DIY Forums

Hi,
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.

Thanks

Bubbling, blistering and flaking paint are signs that the adhesion of the paint to teh surface is poor. This could be a result of a dirty, wet or poor surface. If its damp, and in an underground cellar its a pretty good bet, then ideally one would get to the cause of the damp and eradicate it but thats not usually possible in cellars. The alternatives are to coat the walls of the cellar in a latex based cement coating called tanking, fit a new wall inside the old and let the water in the walls drop down to a formed gulley and have it pumped out or to put up with the damp and paint the walls with a masonry paint which breathes allowing any moisture to evaporate through the walls. The paint is calkled Microporous paint and you may be able to get it from our project ******* in the underground waterproofing project and its also a very good idea to coat the walls in water-thinnable, solvent free silicone/siloxane emulsion which gives great adhesion to micro porous paints and can be found in our underground waterproofing project.

Thank you for your advice doctor. I will give your ideas a try.

David