Dear Donny

DIY EXPERT

QI have a single brick wall between a garage and bedroom which gets damp. If I lined it with plasterboard, which side would work best? There’s a 9cm gap between the wall and wardrobes in the bedroom. Is that enough? And do I need a frame, or would a dab of plaster leave enough of an air gap? Irene Owen, by email

You could dot dab 70mm insulated plasterboard on the bedroom side. But the garage side will probably work better. For that, build a timber frame 200mm from the wall, fit 200mm blanket insulation into the frame, and fix a polythene vapour barrier by stapling it to the timber frame. Finally, fix 12mm OSB boards to the frame.

I had my sandstone sills and pillars on the front of our house ( 1898) repainted by a painter. He filled with Toupret and used Dulux Weather Shield. It was done on a hot week, but two weeks later it rained, and the paint bubbled and split. What could have gone wrong?

Dave Gunn, by email

You have done everything right, so maybe the stone was damp before the paint was applied. If a surface is dusty or chalky I apply a stabilising solution before painting. Try that.

AQA