HI Folks
I'm installing a low-profile shower tray - one of the 'resin' types (referred to in the instructions as 'Not-Easy-Plumb', as opposed to 'Easy-Plumb...)
Anyway, it's going to sit on top of a piece of 18mm ply, supported on
4"x2" timber - all arranged to get the top of the ply level...The instructions insist that, even if you're sitting the tray on a flat surface (like the ply) you still need to bed the whole thing on a troweled layer of 'fine sand, cement and an anti-crumbling agent (Unibond/pva), before sitting the tray on the wet cement 'ensuring it is fully supported'.
The underside of the tray looks as if it has already been ground off 'flush' - so why the need for an additional thickness of sand & cement ?
My initial instinct would be to use some sort of mastic - but the instructions go on to say 'Silicone sealants, foams, mastics or similar must not be used to substitute for cement'....
Any idea why this should be so - or whether flexible tile cement (which I have in abundance!) would be an acceptable substitute for the sand/cement mix ?
Thanks Adrian