I've just bought a new home that has an extension constructed of concrete block work. It was built about 15 years ago as a 'sun room' and had no planning or building regs. Currently this has dot and dabbed plaster board attached to the interior walls, but not other insulation. It is single brick, no cavity etc. I want to get it insulated to make it more habitable in the winter, but building regs flagged that certain insulation may cause sweating (annoyingly did not give any more advice). I wonder if anyone on the forum has any advice? Thanks! Sandy