shower tray to chipboard or on top of tiles. cement mix ?

[powerlord]

Hi guys - last minute question from a newby so hope you don't mind:

my plumber/fitter is fitting a low profile resin shower base tomorrow and also tiling the whole room as part of a refurb.

it's tiles and tray onto a standard green grade chipboard floor (good condition)

First question: most places seem to be suggesting cement/sand mix required under base. Is this really required or would the topps tiles flexible tile adhesive they are using for the rest of the floor and tiles not be fine ? I found a few places saying this, but most saying cement required ?

Second question: they are suggesting tile floor first then fit base on top. It's very low profile 30mm, so I'm not bothered from that point of view, but everything I can find on the internet says base should be fitted to chipboard direct then tiled around.

I can see that this saves them cutting curves in tiles (its a quadrant) and might be a cleaner finish, but they'll be silicon around base anyway surely.

this is the base if it helps - with it being SO low profile it does seem that cement would be a bit of a waste of time ?

https://bit.ly/2NX4cCm

[darrenba]

I use tile adhesive to bed my shower trays

Fix tray first and then tile. Don’t fit tray on top of tiles.

[steviejoiner74]

Tray down first then tile to tray.If it’s going down to chipboard then clear silicone is good enough to set tray with,it gets a really good bond.
Although you can tile directly onto chipboard it’s advisable to overboard with plywood(9mm is fine over a new 22mm chipboard) and screw down every 100mm. It makes the removal of the tiles 10-15 years down the line a LOT easier and removing tiles from a chipboard floor alone is a nightmare,it wrecks the floor and it needs replacing.