Fitting stone shower tray on floor (two plumbers says no cement required?)

[glen8]

Hi Everyone,

We are having our upstairs en-suite done. It is well overdue, and at some point water has managed to seep through the cracks and wet the plasterboard behind. Also, we had terrible banging pipes behind the shower when the downstairs kitchen tap was on.

I've ripped everything out, cut out all the damp and replaced with new. Just waiting for a plasterer (luckily someone in the family) to skim over. I've also cut out a section to access the shower pipes and noticed the builders haven't bothered to secure one of them properly, although both clips had fallen off.

Anyway, I've sorted out the pipes and had two plumblers round to quote for installing a new toilet, basin and shower (tray, shower and screen).

The house was built in 2008 and looks to me to be chipboard flooring? Both plumbers have said to lay the tray straight on the floor simply held down with silicone. The instructions state to use a sand/cement mix but both plumbers said that was rubbish, and would damage the floor.

so....are they right?

First one quoted me £730 labour only, and the second one £300 again just labour. I've bought all the bits already, mcalpine brass trap, toilet waste etc etc

I'll try and put some photos up to make more sense

This was before:

and now:

My plan was to drill a hole for the trap near the existing waste. The new tray has the hole in the center so once laid down it's not far away from the existing waste. This leaves the question for future access, so unless I don't bother, I could cut a section of the floor out near where the basin pipes are. This still leaves the floor solid.

I guess, going all guns blazing I could rip up the floor and replace the lot with marine ply but struggling to understand why two plumbers have said not to bother?

I'd like as straight forward a job as possible, but again, if I'm doing it...might aswell be right.

 

[undertrained]

Good evening Glen,

Do you have a link to manufacturer and tray etc or can you post a photo of instructions? Maybe you could ask the manufacturer? I’ve just researched and quite a few state mixing sand and cement on a timber floor, so maybe ok?

 

[dilalio]

I'd like as straight forward a job as possible, but again, if I'm doing it...might aswell be right.

Its all down to the MI's... Some trays specify silicone but most IME specify sand and cement in a flat, even bed (not dollops).
AND... you should really consider replacing the plasterboard walls with proper tile cement boards!

 

[glen8]

Thanks everyone

Why don't they use this stuff when building the house?

Would tanking the walls and floor be the next best thing?

 

[dilalio]

Why don't they use this stuff when building the house?

Some do. Depends on developer and time/cost saving activities.

 

[dilalio]

Tanking will likely cause issues with tile adhesive. Tile board is the proper product, unless it's a floor with purpose made tanking membrane.

 

[Madrab]

I'd never use sand and cement on a wood floor, they just suck up the moisture ands sometimes don't adhere to the floor properly.

I'd also consider putting an 18mm WBP ply down to lay the tray on . They'll suggest sand and cement as it's much easier to absorb the imperfections of a wooden floor to ensure the tray's evenly supported and leveled. Only time I'd ever consider it is on concrete

2 options as far as the walls are concerned, cement backer board as @dilalio suggests or tank the whole area.

 

[glen8]

We're not having floor tiles, only tiles on the wall

 

[Madrab]

Ooops ... Just saw @dilalio 's comment and not wishing to counter but .....

Tanking edging tape will seal floor to wall and any joints/corners, then the tanking membrane application will provide a waterproof coating (once walls are primed), they are designed to take tile adhesives & tiles, once fully dried.

 

[undertrained]

I'd never use sand and cement on a wood floor, they just suck up the moisture ands sometimes don't adhere to the floor properly.

This is what I thought.

 

[glen8]

Here's a close up of the floor

Sounds like I'll proceed with tanking the walls, just need to be certain about the floor and what product to use for sticking it down with

 

[dilalio]

My post was intended to warn about "Tanking" and the proper systems to use.

As @Madrab has confirmed you use a product such as Impey that have a very sticky backed , cloth type membrane, with an even sticker tape for corners and interfaces between walls and floors.

Its not tanking in a tin which you just paint on....

 

[dilalio]

And just for kicks... The finished room...

 

[lostinthelight]

When I fitted a Mira flight stone resin tray the intructions said to use sand and cement to bed it on.
I didnt like the idea of that so rang their TS who said it was fine to use tile adhesive or silicone

 

[dilalio]

I'd never use sand and cement on a wood floor, they just suck up the moisture ands sometimes don't adhere to the floor properly.

What's your favoured method @Madrab?