Roofing

Looking for guidance regarding 'stains' on the underside (inside) of a new flat metal roof

Anonymous user 28 February 2024 - 2.55 PM

Hi, I've recently put a new metal roof on my garage. It has been put on top of 18mm ply that was then covered with a waterproof membrane, and then with 50mm of kingspan which is directly under the metal roof. The screws for attaching the roof are are in the 'gully' of the profile and going into the ply and they have 'waterproof' washers. I seem to be getting staining at certain parts of the underside of the ply boards and am wondering what might be causing this ? We have had a huge amount or rain up my way and although it isn't dripping through I am concerned that the wood might start to rot. The roof is about 25 sq metres and is on a 3 degree slope. I can provide pictures if required. Any help appreciated. Stevie Hi Kevin and JB Building Services, many thanks for coming back to me on this, it's much appreciated. The sheets are definitely meant to be fixed via the gully and not the ridge; and while I can never be certain I'm pretty much sure that the fixings have been put in straight - however I am of a mind that the seal might be the problem area.Thanks again.