If this was my garage or flat roof extension I wouldn't think twice about it, but it is the main house roof with some fiddly bits around a number of chimneys and a front facade and a total area of 80 sq metres.
Our house has a flat roof, bitumen on board, 80 sq.mt. Our intention is to insulate using Celotex EL3000 and cover with a modern rubber system (Rubberbond).
Celotex comes in a range of thicknesses, what thickness would be recommended to insulate effectively?
How would you best attach a...