Last year I laid laminate flooring in a utility room, the old flooring was concrete with vinyl sheeting, which I left in place. Recently, l noticed patches of white fungus, like the type you see growing on dead trees, appearing around the edges of the floor. These are spreading and growing up the skirting boards.
I sprayed the fungus with weedkiller, which makes it turn black and die, but then more patches started to appear a few weeks later.
Could it be something to do with the vinyl flooring underneath?
Any advice would be appreciated.