Shower tray install

[laverda750]

Hi,
Question regarding installing a stone resin shower tray on a bed of cement mix. Never had one done before so apologies on this. The tray has been fitted , it’s all level but should the tray be able to be lifted back off the cement bed or should it be bonded to the bed (tray was fitted 3 days ago) if it should be bonded to the cement what would cause it not to bond? The sand /cement ratio mix was 5 to 1 as instructed.

Thanks

 

[robinbanks]

personally I would not expect cement mortar to bond effectively to cured epoxy. It’s a mechanical joint, and the smother the surface the poorer the adhesion. Fresh resin being liquid would bond well to cured mortar, as it can sink into the rough surface before it hardens, but not the other way round

If you want that tray stuck down, I’d roughen it with an abrasive then line it with a healthy array of a construction adhesive like stickslike and put it back down in the same place. If the mortar is still visibly soft/not cured I’d avoid disturbing it for a few days as test lifting it will just see the adhesive pull the mortar apart

 

[laverda750]

Thanks,
So the tray does not need to be stuck down just sit on a flat bed of mortar ?

 

[robinbanks]

It depends on whether everything else around it will help hold it in place or not. That you’ve lifted it to find it’s not stuck, can you be sure you’ve got it back in exactly the right place? If it’s in place and hasn’t been disturbed, you could consider tiling and siliconing around it etc but if it’s been disturbed or if it will be surrounded by lightweight things like shower panels, I would use an adhesive as per previous note

 

[laverda750]

I haven’t siliconed around it yet. And it was only the front corner which I checked which moved. I’m thinking maybe I should take it out and start again .

 

[denso13]

Use floor tile adhesive, you can get cement based ones if you prefer.

 

[robinbanks]

In service it wouldnt suffer lifting forces and should have a bead of silicone sticking it down anyway. Mortar beds are for consistent support rather than sticking down something that isn’t lifted in use. If you’re just seeing a little wiggle I wouldn’t necessarily bother, if other stuff will help hold it in place.
If the tiles run under, lift the tray what little you can and ensure you get some silicone under. If the tiles butt up, ensure the gap is narrow and again well filled

 

[Micky1]

Posted in error

 

[Madrab]

but should the tray be able to be lifted back off the cement bed

Not usually

I’m thinking maybe I should take it out and start again

if it can be then yes

Cement beds are an older and trusted approach to bedding shower trays but there are much better options these day IMO. As suggested a good quality flexible tile adhesive being one excellent choice. Newer silicone adhesives are also a good option, especially with flat based stone resin trays and have found that to be very successful. The problems usually start with the tray manufacturers and their warranty and if they specify a mortar bed then, if that isn't used then that allows them to not honour it. That being said it's rare to meet a manufacturer that hasn't found one way or another to get out of a warranty claim, even when the instruction were followed to the letter.