I had some weber fine flow left from an insurance job last year and have screeded my man shed with it and it seems solid, concrete slab, 25mm celotex and 20 mm weber fine flow with 165gm fibre reinforcement. With a tile and adhesive on top it will make it 30mm max on insulation. Just trying things out chaps, if you get my meaning, It's at home I can correct if fails , no sweat. Seems solid though.