Is it ok to lay this tray onto insulation board as the main floor is being built up on this above the concrete oversite and then 40mm liquid screed on top?
I think that this way of preparing a base for the tray should work well, however that 40 mm liquid screed may cause a problem because there's a drainage integrated with the tray which vertical upstand is 15 mm high. You would need to cast the tray somewhere in the screed layer, 15 mm from it's surface. If you're able to deal with that, our product should work well. It has integrated & waterproofed drainage, McAlpine waste trap with pipe and slopes, should be safe and easy to fit and convenient to use.
I am happy to assist if you have any questions.
David 020 7193 0953