I have a shed base on piers topped with plywood that was finished last Winter and covered up to help protect from the elements.
However some water made it through (or general dampness of being covered) through the tarp material and has made the plywood grow a little black mould. The timber joists are fine though, I guess ply is a bit more porous.
I'm going to coat the joists and ply with crecote preservative to help prevent this happening again. Do I need to remove the mould before and if so how. Anything else I can do to prevent further mould - it won't be covered again so I think it was just due to lack of airflow.