If the subfloor is wood waterproof it before using self leveler and before spreading mortar or adhesive.
How to install a shower tray on a wooden floor youtube.
Before you start you need to make sure that the floor beneath the tray is capable of supporting it.
Pearlstone rectangular low profile shower tray.
Good point about the ply raising the level of the floor.
I was not planning on tiling the floor so i will probably go with the cement or silicone method directly onto the existing flooring.
It is firm and pretty level.
How to install shower tray.
This video shows how to install a quadrant shower tray onto a chipboard floor using a mortar base.
Fix an uneven floor using a self leveler.
If the floor is not level the shower pan will not be able to drain properly.
Of the two designs these are generally a bit more complicated to install because they fit directly onto the floor with no gap in between.
This guide explains how to install a shower pan over existing plumbing.
The ratio for the mortar mix was 5 sand to 1 cement.