Flat roof install, DIYer. I haven't yet put the new OSB on, and when googling, I found some images where the OSB seems to extend out, and the fascia board is under the OSB, and others where the top of the fascia board (uPVC 18mm thick - from eurocell) is level with the upper surface of the OSB. Is there a recommended way ? Or is either "ok" ? (FYI - will ultimately be a rubber EDPM roof going on with appropriate drip battens, and endge trims etc