@willbishNo it is due for delivery in the next few days..... was just reading through @PeterW recomendation https://www.wundatrade.co.uk/shop/home/20mm-eps-400-overfloor-board/ and just trying to work out the best possible outcome with a MAX floor build up of 130mm  so far i had  Insulation 90mm (probably two layers with cross battens) attached to floor Some sort of sub bace wood under floor 18mm attached to battens  Wunda underfloor heating board  20mm glued to sub. Flo