Dansin

Thanks for that. Both concrete floor solutions look to be suitable. As it is effectively new build do you think there is a need to use the CI matting, or will flexible adhesive and grout be just as good?

I'm guessing that the fall on the trays will be approximately 10mm from edge to center, which would only leave approximately 60mm to the c/l of the 40mm waste. Can you recommend a horizontal trap that would fit within that dimension? The base of the trap could be cut into the underlying insulation but the height of the waste is already fixed.

Thanks

Daniel