If only it were that simple :(

This is a 'warm roof' so the GRP is bonded to the insulation, 120mm Kingspan polyurethane, which is itself pinned to 6mm marine ply over the joists. On the bottom of the insulation is a vapour barrier. any fixing to the joist would need to penetrate the ply and the vapour barrier and the insulation, and should have a thermal break in it to avoid cold spots/condensation forming...


Quote Originally Posted by Neale View Post
Will the GRP take the load anyway, assuming you could fix to it, or will you have to get a fixing to the underlying structure?
Maybe piece of angle screwed to side of joist and against bottom of GRP panel, hole drilled through both and then bolted together with external penny washer and appropriate sealant. Leaves protruding stud to take panel fixing bracket? My boat has plenty of examples of this kind of seal, underwater, and good for life of boat. I hope...