How do i install a shower tray?

i have a shower tray to install on a concrete floor, i have to raise the tray to accomodate the drainage, if i am raising the tray, what do i support the tray on? a wood framework or a stone/brick method? i realise i need to retain some access to the trap for the future. the tray is 1500 x 700mm and made of a composite material, not all plastic but a combination of stone/plastic with a central waste.