I had an extension built 3 years ago. We had a metal patio door fitted and a wooden floor that was made of reclaimed boards. After about a year I've noticed that the floor has started to appear marked. Lots of tiny cracks have appeared that have taken away the shine and given it a worn look and also some marks that look like water stains. This has got worse in the last 6 months or so. Its only happening by the door but it seems to be spreading back from it. I took up a board today thinking that maybe some moisture was getting under the door (which has some orange foam under it) but it is all dry. Any idea what this is? I varnished the boards originally just after they were put down. Thanks for any thoughts.
It was varnished with ronseal diamond hard varnish
It was varnished with ronseal diamond hard varnish