How to waterproof under a raised shower tray?

[smallsteve]

I am about to fit a raised shower tray and wonder if I should concern myself with putting some kind of waterproofing material in the hollow underneath the tray e.g some kind of membrane? If so, what would be used?

 

[Ben-gee]

Not needed, and no real point putting membrane unless it leads into a drain, but don’t worry it’s not needed here.