So Andy, this is a floor laid on plasterboard? I thought you meant a gypsum screed, ie calcium sulphate, I was going to agree with Dave about the sweat test. But is this just water damaged joists? Not to sure what the problem is now.
Evening phil! It is a gypsum based floor mate!not pboard....the joists under the step and shower are goosed hence ive ripped them out.its just the floor is taking a while to dry?.... Lol