The directions with the tray instruct the installer to mount it on water restant ‘green’ chipboard and ensure that the bottom of the tray is fully covered with a 5mm bedding layer of silcone or mortar. It then goes on to suggest that the unslotted waste should be taken through the tray and the chipboard sandwiching both with the backnut. Is this the correct method to install the waste, rather than fixing the waste to the tray only and leaving a clearance hole in the chipboard for the backnut. Thank you.
Putting the backnut over the ray/ chipboard sandwich will provide access for future repairs. To instal backnut on the tray with clearance hole in the flooring will make removal difficult at a later stage. In Britain shower traps are available that are secured from the basin part of the tray. This item would have to be fitted with a clearance hole cut in the chipboard.