If you are getting that, there's a good chance that your concrete floor has no DPM and the moisture is travelling up through the slab. Two coats of an epoxy (doesnt have to be coloured) would stop this.
Pretty sure they were doing a deal fro all 3 for £399...I’m hanging on at the mo as discounted its £439...
Flush ply fire doors with a solid core make very good worktops, 44mm thick and can be cut to your choice of width. Steve