This isn't strictly Home Cinema, but as a lot on here have converted garages you might be able to help me out. I'm not quite up to starting my garage conversion yet, but have a little bit in my hallway that is sijngle brick that will need insulating. Basically it used to be a porchway for keeping bins, etc, but previous owners converted it to a downstairs toilet/hallway. Anyway, it wasn't done very well and the usual things need putting right, the floor needs to be raised to meet the house level (and insulated) and the outside walls are just single brick and so need insulating. As the wall has been built almost paralle with the existing internal wall I can't really come into the house much, so can't really build a cavity. I'm after the best but thinnest method of insulating single walls. The best I can think of at the mo is lining the wall with polythene, battening with 2x1 and then using something like the Wickes 30mm fibreboards/slabs, then plasterboard over the top. Is there any insulated plasterboards that I should consider that would insulate well but not be too thick, or am I better off with a method as I suggest?