I bought 12 sheets of WPB instead of using the OSB supplied with my shed, as I needed the extra strength and water resistance, then put a Rubber roof on the top. At Christmas I noticed one board in the roof had developed black spots - three months after the roof went up -and I complained to the supplier (can I mention them? G&D) who said I should have treated it before I put it up! I cleaned the mould off but it has rapidly reappeared, and it is in only one board, so I believe it was in the board before I put the roof up. My only worry is that there is an air bubble in the rubber (it was my first attempt at doing this and I was later told I should have used a hair dryer on it.....) though I doubt this is the cause of the mould. I'm stuck between a rock and a hard place because I can't replace the board because it would mean trashing the rubber roof. Note, this is a big shed: 6m x 3m.
Any views on what I can do to stop the mould?
Any views on what I can do to stop the mould?