Fixing pearlstone shower tray

[rreanor]

I have a pearlstone shower tray I need to fix to a raised timber base in an upstairs bathroom. It's very heavy.

I've used 18mm osb3 instead of ply as the base, as I had a load left. Does this matter?

Also, do you really need to fix it with cement based adhesive, or can you just use some decent quality tube adhesive like CT1 (again which I have loads of)?

 

[Madrab]

OSB3 is fine - any water resistant surface is what's needed. Ideally the space would then be tanked.

I don't use cement based adhesives any more, I have more problems with that than anything else. Any good silicone adhesive works for me just ensure that the plinth and tray is level, once it's set down before fixing. Use enough adhesive points too, especially along the outside edges and along the entire wall contact points (top edge, side and bottom) and take note of the tray's under surface and what sections will sit flat to the board. Always check the tray too, ensure the base is flat, square and clean.

 

[rreanor]

OSB3 is fine - any water resistant surface is what's needed. Ideally the space would then be tanked.

I don't use cement based adhesives any more, I have more problems with that than anything else. Any good silicone adhesive works for me just ensure that the plinth and tray is level, once it's set down before fixing. Use enough adhesive points too, especially along the outside edges and along the entire wall contact points (top edge, side and bottom) and take note of the tray's under surface and what sections will sit flat to the board. Always check the tray too, ensure the base is flat, square and clean.

The only issue is is that the bottom of the tray is not quite flush with the bottom rim of the tray towards the trap, which means there will be a slight gap between the plinth base and the underside of the tray (except the rim), and therefore the adhesive won't bridge the gap adequately. Is this normal? I wonder if they are designed for a thicker bed of cement adhesive for which silicone can't really provide. I attach a pic with a straight edge across so you can see the gap at one end of the tray.

 

[Madrab]

Yes, some of the 'generic' trays end up like this where the outside edge isn't level with the main body of the tray. In these cases I normally use a piece of 3/5mm WBP/hardwood ply to fill the gap. I.E. fix the filler piece to the underside of the tray using adhesive, then when the tray is placed down onto the plinth, there will be no gap.