Hi, I am after some advice, I live in a 1939 built detatched bungalow with a 3 layer felt roof, this was replaced in 1989 after storm damage, From memory when they renewed it, the sub structure was planks/boards of solid canadian timber about 19mm thick. I had a quote from someone doing a roof opposite who said they would use a machine like a lawn scarifier to remove the grit off the existing felt and then coat it with a resin for £9500.
Looking at the roof in my opinion its at the end of its life, I was thinking of doing it myself in GRP, I have done 2 garage roofs with it in the past and had no problems, I did have experience with grp repairs to cars etc. The roofs on the garages were replaced with 19mm marine ply and then the roof bonded to that.
Question, if i removed the existing felts would it be ok to board over the sound sub roof/planks with 6mm osb3 or ply screwed to the existing wooden structure and then bond grp to that or would i have to use 19mm osb?My thinking is I only need to provide a good stable surface to bond the grp to as the sub roof is sound and stable, I would obviously replace any damaged / rotten sub sections before boarding over and grp. I shall also have to think of someway of making it water proof after laying a section, I figure I can remove felt and board and grp and top coat a area the size of a single garage in one day I shall have about 10 times that area to do.Any help guidance would be greatly appreciated, thanks in advance.