How can I completely seal around a concealed 3 way shower mixer in a Kerdi Board shower wall. - Tile Advice

[JM123]

Hi Everyone,

My plan is to install Kerdi Board in my bathroom, tank it, then tile. I was going to get a 3 way shower mixer (Bristan Descent) but when I look at the installation instructions it shows a cut out section at the front (to access the valves presumably). My question is how do I ensure this cut out doesn't get water into it? I'm guessing the shower mixer front plate is sealed against the tiles with something like silicone sealant? However, my (limited) understanding is that since the water can get in behind the tiles through the grout it could then make its way into the cut out area of the Kerdi Board and therefore get behind it and into the stud wall.

I'm no doubt missing something or misunderstanding something here, could anyone help me out? Any thoughts or comments would be greatly appreciated.

Cheers,
James

 

[Dumbo]

Get a Hansgrohe ibox then it has a sealing flange .

 

[WetSaw]

...and you don't tank Kerdi board, just seal the fixings and joints with Kerdi band.

 

[One Day]

Imagine spending good money on installing kerdi board and then an idiot builder priming it all with blue-grit then a plasterer skimming it and then the builder helpfully pva-ing it all before passing you a tanking kit to waterproof the lot.
It happened to me!

 

[JM123]

Hi jcrtiling and pdc, thanks for your responses.

jcrtiling, do you know if there is a Hansgrohe iBox that would fit a Bristan Descent 3 way mixer? I've had a look at their website and one of their installation videos and they look like they are specifically for the Hansgrohe shower mixers. I'm surprised every manufacturer doesn't have their own one for each of their concealed mixers, how do they expect people to seal them?

pdc, yes you're right, sorry, thats what I meant, I do have have Kerdi Coll and Kerdi Keba to seal the joints.

Cheers,
James

 

[One Day]

It is simply a weak point in the installation. The valve is supposed to be accessible in case of service so you'll be relying on sealing the face plate securely.
Clear decent silicone is all you can really use.
As suggested, the ibox is the proper way but they come at a price.
As a different idea, you could make a gasket yourself out of kerdi keba, and seal that around your valves using kerdi fix, but personally, I wouldn't bother.

 

[JM123]

Thanks impish, I think I'll just go with the clear silicone as you suggest. I did look at the ibox but couldn't find one that looked like it would fit the shower mixer I have.
I was thinking of leaving some of the the kerdi board exposed (ie not tiling right up to the edge of the cut out section) and running silicone sealant around that as well as the tile surface, that way at least there would a seal between the kerdi board and the face plate of the shower mixer (as well as between the tiles and the face plate) and that might limit any ingress of water into the cut out section.
Do you think this would help at all?
Cheers,
James

 

[macten]

When we talk about ingress of water through grout joints we are talking about a little bit of moisture (assuming tiles have been fixed and grouted correctly) - don't stress about it and just seal the plate with a thin bead of silicone.

 

[JM123]

ok cool, thanks macten and thanks again to everyone for taking the time to help me out, I really appreciate it.