Supporting a shower tray

[Adrian]

HI Folks

I'm installing a low-profile shower tray - one of the 'resin' types (referred to in the instructions as 'Not-Easy-Plumb', as opposed to 'Easy-Plumb...)

Anyway, it's going to sit on top of a piece of 18mm ply, supported on

4"x2" timber - all arranged to get the top of the ply level...

The instructions insist that, even if you're sitting the tray on a flat surface (like the ply) you still need to bed the whole thing on a troweled layer of 'fine sand, cement and an anti-crumbling agent (Unibond/pva), before sitting the tray on the wet cement 'ensuring it is fully supported'.

The underside of the tray looks as if it has already been ground off 'flush' - so why the need for an additional thickness of sand & cement ?

My initial instinct would be to use some sort of mastic - but the instructions go on to say 'Silicone sealants, foams, mastics or similar must not be used to substitute for cement'....

Any idea why this should be so - or whether flexible tile cement (which I have in abundance!) would be an acceptable substitute for the sand/cement mix ?

Thanks Adrian

[Peter Johnson]

I can't answer the question but for the last five years my shower tray has been sat on a bed of tile adhesive without any problems; I assume that the fitters got into the habit of using because it was to hand.

[Ed Sirett]

No you want to get the top of the tray as installed level. IME the trays are not level within themselves. Especially at the commodity end of the market.

Arse armour IMHO. A reasonably thick bead of silicone/stix-all/CT1 should do the same and be less messy.

Even I'm beginning to get a little worried. The reality is that a well constructed base bedded with some gunk to spread the load and I'd risk it. The tray is unlikely to break if it does they have made things as hard as possible to make a claim. The real cost won't be the tray anyway but the dismantling and refitting of the enclosure etc. I bet that's not covered anyway.

My 2p worth 0p

[Adrian]

Ah - that's interesting - thanks

See also my reply to Ed

Adrian

[Adrian]

Fairy 'nuff....

I have to adjust the levels anyway - as the new shower tray is being installed to sort out the existing c*ck-up of an attempts at a built-in shower/wet-room thingy with a (semi)-sloping floor - so there's room for a bit of adjustment with the timber so as to end up with the right level on the top of the tray.....

Well - that's what I thought... and even had a couple of emails back & forth with the manufacturer's tech support people (very responsive, actually)..

I suggested that a combed bed of tile adhesive would (might!) be suitable quote ---- I am unable to confirm if you particular adhesive is sufficient for the purpose. However, I would strongly recommend the use of an adhesive based on Portland cement or cement in general.

I would also strongly recommend an even screed of material over the total surface area and NOT the use of a notched spreader, as this has been shown to form high spots for the tray to belly out on when and if the material should cure too quickly during installation.

---unquote

Does sound a bit like backside-covering, to me....

Probably not

Despite all the dire warnings, I'm leaning towards combed tile cement - after first having got the timber structure set up to achieve 'level' on the top of the tray...

Not at all - very helpful - and kind of reassuring... This is the first of these 'resin' trays I've fitted - always used the old-fashioned ones before - foamed core and acrylic top surface.

I'll give it a try with tile adhesive - once my timber turns up (this unusually cold weather's a gift for suppliers out here on the edges of the civilised world - currently waiting for four seperate deliveries of materials... and want to get on with things !!

Thanks Adrian

[Adrian]

Fairy 'nuff....

I have to adjust the levels anyway - as the new shower tray is being installed to sort out the existing c*ck-up of an attempts at a built-in shower/wet-room thingy with a (semi)-sloping floor - so there's room for a bit of adjustment with the timber so as to end up with the right level on the top of the tray.....

Well - that's what I thought... and even had a couple of emails back & forth with the manufacturer's tech support people (very responsive, actually)..

I suggested that a combed bed of tile adhesive would (might!) be suitable quote ---- I am unable to confirm if you particular adhesive is sufficient for the purpose. However, I would strongly recommend the use of an adhesive based on Portland cement or cement in general.

I would also strongly recommend an even screed of material over the total surface area and NOT the use of a notched spreader, as this has been shown to form high spots for the tray to belly out on when and if the material should cure too quickly during installation.

---unquote

Does sound a bit like backside-covering, to me....

Probably not

Despite all the dire warnings, I'm leaning towards combed tile cement - after first having got the timber structure set up to achieve 'level' on the top of the tray...

Not at all - very helpful - and kind of reassuring... This is the first of these 'resin' trays I've fitted - always used the old-fashioned ones before - foamed core and acrylic top surface.

I'll give it a try with tile adhesive - once my timber turns up (this unusually cold weather's a gift for suppliers out here on the edges of the civilised world - currently waiting for four seperate deliveries of materials... and want to get on with things !!

Thanks Adrian

[Huge]

As I discovered a few months ago when I fitted an Aqata minimalist cubicle onto a gawdknows low-line tray. Despite all the faffing about taking the bathroom floor up and replacing it with 18mm WBP, bedding it in mortar (*) and taking huge pains to make sure it was level, it turns out the top isn't bastard flat. There was a nearly 5mm gap at one corner where the tray dips down. :o(

(* I used foam round the edges. Belt and braces and all that.)