I am about to replace my slate roof and have a couple of questions:the roof has never had a membrane and I intend to strip off the slates and put down a good breather membrane. There is fibre glass insulation between the rafters ( done from below when the attic was converted). If I'm putting down a breather membrane can I leave the fibre glass insulation or am I better off replacing with maybe 50mm celotex insulation board to leave a 25mm air gap ?
Also there is big price difference between lead for the valleys or GRP valleys. I really want to do the job as best I can so should I use lead ? TIA
Also there is big price difference between lead for the valleys or GRP valleys. I really want to do the job as best I can so should I use lead ? TIA