Shower tray - installation options

[kjacko]

Hi all,
So got an Orchard 1400 x 800 stone resin anti-slip shower tray.
If anyone knows the brand it has 9 nylon screws that you use to level the tray, but the instructions states it needs to be laid directly onto marine ply (not floorboards) or a concrete floor.
Now, it’s my in en suite and I replaced the floorboards where the tray will sit with 18mm ply (probably not marine). I’ve since primed the entire floor with mapei eco ultra grip extra and then screeded it’s with mapei ultraplan renovation. Sadly the floor hasn’t turned out as flat as I’d have liked.
I’ve tried to contact Orchard but they are about as much use as a fishnet condom.
So I want to know if I can lay it on a screed using the nylon screws supplied or if it’s likely to crumble under the screws?
Also if using the screws how on earth do you alter the ones at the back of a 34kg tray when it’s sandwiched into a 3 wall enclosure?
The alternative is weak sand/cement mix OR flexible tile adhesive. If I go down this route then surely I can dot’n’dab considering if I just used the screws then they would have been the only points touching the floor thus implying a full support bed isn’t necessary?

Would very much appreciate advice on this.

Thanks

 

[Madrab]

The tray will point load any weight down through the screws, Plywood will deflect slightly to accommodate that loading, will a screed ... probably not.

You would level the tray dry before final fit to level it all out if required

If you use a fixing/bedding method that isn't in the MI then the warranty could be invalidated, if that's important. If not then take the screws out and use whatever bedding method you want. Ideally though the sub floor wants to be dead flat so levelling the tray then isn't required.