Hi. I'm after some advice on methods of installing insulation board behind plasterboard. I've just removed a fitted wardrobe from an external wall of my 1940s semi and the plaster behind was blown so I've removed it back to brick. It's a cavity wall on the first floor and appears to be dry. As it's an external wall I want to insulate it internally before plastering. From what I've read the usual way to do this would be either to install battens and then insulate between them and plasterboard over the top, or dot and dab insulation backed plasterboard. However, I got a plasterer in to quote for the job today and he said he would use separate insulation board (Kingspan or similar) which he would sandwich between the wall and plasterboard, using mechanical fixings through both plasterboard and insulation into the wall to hold them in place. He would then skim over the top. He says he's used this method in his own home. As everything I've read on the Internet talks about either dot and dab or battening (both of which presumably leave a gap between the wall and insulation) I'm wondering if his method is just cutting corners or is a sensible approach. Is there any problem with not having a gap? Are there any other problems with this method? Any advice much appreciated!