What board best under shower tray?

[yartin]

I have been very satisfied with the Mira Flight series trays......stone resin with a quality capping and they come with a quality outlet.
They must be installed completely flat and on a medium that gives a cushion - the rep said that a thick bead of silicone was fine. Check if the outlet position suits you!
I don’t like the leg riser kits, and prefer a timber plinth if I need it raised.
As for an enclosure, buy the best you can afford - mine all came from Screwfix, delivery direct from the manufacturer.
John

Yes I am looking Mira Flight on screwfix, it will be joist then 18mm marine plywood then tray. No leg riser kit. Apparently they are the best made and silicone is good enough for these
waste is an issue as there are two joists on the way. see pic below, what do you recommend?

 

[Burnerman]

For sure, the drain needs good access just in case it needs maintenance later.
It’s possible to install timber ‘trimmers’ which effectively bridge the cut away joist without losing any strength. A similar application is found where joists meet up to hearths.
I have four Mira trays, and they have had offset outlets rather than centre - but I didn’t buy them at the same time so perhaps they vary.
John

 

[Burnerman]

Do make sure the tray can’t rock on your supports, and bedding it down on silicone will be just fine.
John

 

[yartin]

Or may I can use long path for the waste pipe 240cm?

 

[Burnerman]

I guess the shortest run is the better, but as long as you can get enough fall on the pipe, and have it well supported especially at the joins, all should be well.
John