Hi ,what is the best membrane to use under tiles,i have to replace my membrane as it is starting to break up and crumble. The roof is piched and butts onto the existing house(its a dinning room extension) been up about 25 yrs
any breathable felt, normally in 1.5mtr wide by 50mtr rolls or 1mtr by 50mtrs. TYVEX is one of the best but there are so many out there and the price can vary quite a lot. Dont forget you need to replace battens these must be treated and normally 25mm x 38mm.