J
jackrussell31
HiI am tiling the floor of a wet room/bathroom with 457x305x10mm Limestone. The base is currently 18mm chipboard (screwed down) on 1st floor joists. The area is T-shaped - 3.4 x 1.8m with a 0.6 x 1.8 spine running between the bath and 1500x1500 Fundo Wedi tray. This tray is recessed to the joists (18mm plywood base and sump PVA'd) leaving a 25mm step once fixed with 3mm cement based adhesive.I intended to insulate with 10mm insulation board on top of 4mm ply (screwed down) and then screw down 11mm marmox to level the floor with the Fundo tray and provide tanked base (also tanking walls with marmox).So the question - I read in this forum that a decoupling mat takes out lateral movement of the wooden floor. So inlight of the fact that I have a laminated sub surface and marmox top (prior to UFH and tiling) do I need a decoupling mat, which I assume goes on top of the marmox and doing away with the 4mm ply so that I can maintain a level.I hope that all makes sense - happy to clarify if not.Many thanksJack