Shower Tray Advice for install

[alfa20ad]

I have a stone resin tray to install at the weekend. The question I have is the existing flooring is 22mm T&G chipboard. Do I cut this out and put down some 18mm marine ply or just fix the marine ply on top of the existing flooring then 5:1 dry mix mortar and then lay the tray. Also would 20mm deep mortar be sufficient for the mortar base???

 

[Ben-gee]

Cut out chipboard and replace with ply, prime this with acrylic primer or SBR.
Set the tray on flexible cement based tile adhesive making sure entire base is supported - if it’s flat bottomed 10mm is sufficient , if it’s ribbed 4mm is sufficient as it will be much thicker up into the ribs.
Check floor with level first so you know where to put more adhesive. This will make it easier to level the tray without too much adhesive squeezing out.

 

[alfa20ad]

Cut out chipboard and replace with ply, prime this with acrylic primer or SBR.
Set the tray on flexible cement based tile adhesive making sure entire base is supported - if it’s flat bottomed 10mm is sufficient , if it’s ribbed 4mm is sufficient as it will be much thicker up into the ribs.
Check floor with level first so you know where to put more adhesive. This will make it easier to level the tray without too much adhesive squeezing out.

Manufacturers instructions is for mortar, will this not invalidate warranty if using tile adhesive? Also it’s marine ply, is sbr needed??

 

[Ben-gee]

Just telling you what I’d do/ have done dozens of times (maybe hundreds actually).

 

[alfa20ad]

Just telling you what I’d do/ have done dozens of times (maybe hundreds actually).

Thanks for your input. Why do the manufacturers refer to cement and not a flexible tile adhesive?
Is this to cover just in case the flooring underneath is not level?

 

[king of pipes]

6mm Hardie backer glued and screwed down on top of the chipboard then as Ben gee SBR primer then use flexible tile adhesive to bed it down tried and tested method . Cheers kop

 

[Ben-gee]

Because they haven’t updated their instructions for years to reflect current materials and practice.
The idea is that the tray is set upon something solid that won’t flex and provides full support over the entire area of the base ie NOT silicone, expanding foam etc etc that the plonkers use.

 

[alfa20ad]

Because they haven’t updated their instructions for years to reflect current materials and practice.
The idea is that the tray is set upon something solid that won’t flex and provides full support over the entire area of the base ie NOT silicone, expanding foam etc etc that the plonkers use.

Well I cut out the chipboard this afternoon and I have some no more ply SBR, will brush that on the marine ply and go for the flexible tile adhesive - which do you recommend? Cheers.

 

[Ben-gee]

To be honest any single part flexible is up to this job I would imagine. I occasionally have used the ends of several different bags to clear out the back of my van!
Go to your local tile shop/merchant; grey is cheaper than white, rapid set is cheaper than slow set.
So, grey rapid set single part flexible would be a good choice (S1 class is fine , S2 is not needed and more expensive/ trickier to use )

 

[alfa20ad]

The tray is fairly flat underneath, shall i back butter prior to bedding???

 

[king of pipes]

SBR the back of the tray and the floor then adhesive the on floor . Kop