My shed is over 10 years old but is in reasonably good shape - some rotting along one edge at the base where its next to a border. The roof was re-felted last year but the roof boards inside look very wet and there is a lot of white furry mould inside the shed. There is no sign of leaks on the roof. The felt isn't torn. We did leave the old felt underneath, which I know we shouldn't have but that shouldn't cause the dampness inside to continue. It's been over a year since it was re-felted. Could something else be causing the dampness inside? It's on the side boards as well. Is it a sign that the sheds on its way out?