We're insulating an existing house before we move in. The only weak spot left is the kitchen tiles on the concrete floor and I had thought to put tilebacker boards under them, the type that are used under electrical underfloor heating systems. I've been quoted 53 Euro/sqm inc VAT however for a 10mm sheet of the best known brand on the market here in Ireland. That's more than we're paying for the tiles! Can I get away with putting 12mm of WBP ply under them instead? If so, what's the best way of securing the ply to the concrete floor?
