Mark Crane
Hi First make sure your tradesmen has been on an Asbestos awareness course, (should have a certificate to show you) This is a very costly waste to dispose off, if you have a good local waste department they should allow you to double bag the broken up sheets free of charge, if you use a skip it could cost upward of 500.00 pounds. Make sure the roofing company is aware of and is responsible to deal with this waste. Is the room to be used as living accommodation? if so you need a warm roof construction, this will need extra timbers enabling the 8 x 4 roofing boards to be fixed at .400 centres, over this a Vapour control layer (visqueen) is laid, then ridged PIR insulation (thickness to be calculated) then over laid with either rubber EPDM or a single ply membrane. If you are not using the room to live in then omit the insulation and Vapour control layer. Trust this helps Regards Mark, Protech Installations (UK) Ltd
