We recently moved into a house with a large dormer window/flat roof which we knew would need replacing. We engaged a local roofer to do the work, but he turned out to be a cowboy who replaced the boards, but we have not heard from him since (4 weeks now). My sister’s boyfriend (a builder) offered to finish the job, and we accepted. The first time it rained after he finished, we had water come in through the gaps in the newly replaced plasterboard ceiling. It continued to drip for at least 36 hours after raining, indicating water retention somewhere. The question I really have is what needs to go down underneath green mineral felt on a flat roof, as I think there may be nothing between it and the boards (waiting to speak to sister’s boyfriend). And should I just bite the bullet and get a proper roofing firm out to do the roof with the rubber stuff? Sorry for the long post!