It is firm and pretty level.
How to install a shower tray on a wooden floor youtube.
Fix an uneven floor using a self leveler.
How to install a shower tray by building the base out of a timber frame topped with plywood and cement and applying silicone sealant around the shower tray.
How to install a low profile shower tray.
If the subfloor is wood waterproof it before using self leveler and before spreading mortar or adhesive.
Good point about the ply raising the level of the floor.
This guide explains how to install a shower pan over existing plumbing.
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.
If the floor is not level the shower pan will not be able to drain properly.
Before you start you need to make sure that the floor beneath the tray is capable of supporting it.
I was not planning on tiling the floor so i will probably go with the cement or silicone method directly onto the existing flooring.
The ratio for the mortar mix was 5 sand to 1 cement.
Pearlstone rectangular low profile shower tray.