How to fit flush shower tray level with concrete slab

[markharro]

I am trying to coordinate the detailing for our slab pour to ideally accommodate fitting a rimless and flush tray - thinking of using this https://www.my-bette.com/en/products/further-product-topics/betteair

 

The slab will be 150mm thick and will be our final surface so no screed on top. We cant have screed as we have UFH pipes at 50mm below the surface and the company doing this insist on this minimum 50mm cover from the main concrete pour. So my issue is I can just about see how we could use formwork to get a recess in the slab  during the concrete pour for the tray but how do we make the interface between the slab and tray waterproof and also how do we get a neat interface line?

 

thanks

[Simplysimon]

2 hours ago, markharro said:

UFH pipes at 50mm below the surface

is it not possible to put the ufh pipes 100-150mm down?

[Chanmenie]

Don’t fit the UFH pipes under the shower tray, cut a hole the right size in the rebar and make a shuttering box exactly where you want the shower tray to go.

Im doing similar with mine

[JohnMo]

My pipes are at the bottom of a 100mm concrete slab, directly stapled in to the insulation. So an over pout could be done, but you don't need to.

 

Where you want your shower tray form a void so the concrete is missing.  Make a plug out of 50mm foam or PIR slightly bigger than the size you want your tray, position exactly (some wiggle room as you are making plug oversize).  Wire down to where your UFH pipes wil be.  Do pour and after a day or month or two break out the plug and you have a void for your shower.  Make sure you have space and have for drainage.

[markharro]

Hi @JohnMo thanks for this. I had thought make the plug slightly smaller. If larger how do you deal with the gap once you put the tray in? That and the fact that it will likely be a bit of a ragged mess. I thought smaller and then grind the perimeter to exact size once hardened to match tray size. And I still dont understand how you make the interface between the slab and the tray watertight?

[JohnMo]

You could that way. Or fill with some concrete/ cement once positioned.

[markharro]

Thanks again but that would prob not be precise enough for my fussy partner. The idea is that we have a sharp straight edge at the concrete to butt the tray against. Its this detailing that is causing me the problem

[Iceverge]

What is your final floor finish? Polished concrete? 

Tiles? 

 

 

[markharro]

This is the point. Its the concrete itself - powerfloated rather than polished but same difference.

[JohnMo]

Our floor was power floated, it's not what you would want as a finished floor.  You certainly would have any hard skin on your feet if walked about without socks on.

 

Make sure your contractor is aware he is doing a finish floor, power float and finished floor are not the same.

[Tom]

We're having our slab as the final floor finish too - it will be powerfloated on the day it's poured, but will then be ground back/polished about 6 weeks later I believe. How long you do the grinding will dictate the finish on the floor. We want a relatively satin/matt finish so I guess this will be minimal.

[markharro]

Thanks - all good points - we have been in a house with a power floated floor as the final finish and were quite happy with it but I do get that a lot will depend on the amount of care taken at the time.

[Mr Punter]

I think you will really struggle to make this work.  The concrete may not be flat enough, the edges could be chipped or ragged, incorrect size etc.  I have used a flat shower in a posh hotel and the water went all over the bathroom floor.  Really slippery and wet feet all the time.