Clean it off, find the leak, spray it, ventilate and forget about it. Do it yourself for £20. Legal recourse? FFS?
In fairness, the post says 'clean it off, find the leak, spray it [presumably with anti dry-rod goo], ventilate it, and forget about it'.One of your responders advises to: "Clean it off ... ... and forget about it". What dangerous nonsense to give out on an advisory forum - what ignorant smugness, its worse than trolling.
What if some children were playing on that floor and it collapsed?
It also says its a joist in an outbuilding, not a floor....
Daniel