Shower Tray onto Hardie250 or Ply (WBP)

[gherkin]

Hi guys

very quick and probably simple question, can the shower tray be cemented onto a HB250 or does it have to be straight to ply. Doesn't make much difference for me either way, just that I have enough HB to to allow it.

On that note how does the cement effect the ply - would it eventually rot through as obviously its water based?

Thanks