Fitting shower tray on floor boards

[Best]

Sand and cement is near unworkable with a light bed - and especially on dry wooden floorboards.
I would like to stand and watch the people who write the instructions of bedding the shower tray, doing it with sand & cement!
Flexible floor adhesive seems a proper way to do it. I must admit that I often use plaster to bed trays down where they need a thin bed & I can't see any thing wrong with that.

 

[Ermintrude]

Remove boards fit ply so level with tops of joists then a nice thick bed of compo

 

[smhstu]

I use ct1 or Adiseal