A 2003 Semi D - In the process of installing soundproofing in one bedroom which is one room subject to noise from the other semi D that I need to address. We have checked the construction; Separating us and next door - or rather joining us! is approx. 23cm [2 layers of plasterboard, looks slim~10mm each, 75mm stud and yellow insulation, 8mm woodboard, 1cm air space, 8mm woodboard, 75mm stud and then the same again 2 layers of plasterboard on the neighbour's side]. Anyone we have mentioned it to - from the acoustics people, to the window fitters to the plumber are really surprised there is no brick in between us and next door. I have checked with a friend who does fire investigations - in particular re the attic - as it is only plasterboard and stud - no insulation and no timber and some gaps at the sides - he said that this offers 60 minutes fire protection and doesn't see an issue. Any thoughts? Next port of call the relevant SIs for the local authority.