BackerBoard on top of Shower Tray or Tray butted up against Board?

[dave100]

Hi there,

I'll soon be installing a SONAS 1500 X 800 resin shower tray in a bathroom that I am renovating. It does not come with any sealant or tape.

The shower tray will be against an external concrete wall which I will insulate and put some Hardie Backer Board on.

My question is, does the shower tray go like this, Option 1: (Tray against backer board):

Or like this, Option 2: (Backer board on top of Tray):

Obviously, my main concern is how to make the best watertight seal. I know I need to tank the whole lot when done.

I bought this Classi Seal Wtaerproof Rubber Upstand which goes on the outside of the tray
That would suggest Option 1 is better?

I have a related question:

I need to raise the shower tray by about 70mm over the concrete floor. People suggest lots of ways to do this. Marine ply with something underneath? Bricks set with sand & cement and set the tray into the same & cement? Some use tile adhesive under the tray, others don't? Any thoughts on the best way to set a 1500x800 resin tray?

If using sand & cement what is the ratio of the mix?

Thank you guys, as always!

Dave

 

[ShaunCorbs]

Option one but as your insulating have a look at marmox boards you could get rid of your insulation and hardie steps and combine it in one product

50mm timber and 18mm ply and tile addy for the tray

 

[king of pipes]

I'd use thermopanel tile backer insulation boards they will do both jobs in one product , able from uheat online. Build a base as Shaun recommends or purpose made tray riser kits are available? , personally I use a good quality silicone to seal the the tray against the insulation boards or wall a wooden prop against the tray holds it while the silicone sets . Kop