Hi,

with my extension I am currently getting a new wetroom on the first floor and I am trying to ensure the job is done right I am not a tiler so I don't claim to have a clue about this but have spend quite some time reading the forum and elsewhere.

My current setup is:
- new suspended timber floor with MDF type floorboars
- the MDF floorboard has been cut out to sink in a Marmox tray
- the rest of the floor has been covered with what looks like 8mm marine board
- the wetroom tray joints have been taped with a mesh scrim and ARDEX WPC was
applied on top of this

I have a couple of questions:
a) Does the above sound about right in terms of what has been done so far?
b) As a next step does the whole floor need to be covered with a layer of the ARDEX stuff (including the wetroom tray)?
c) Would it be overkill (or even possible) to put a membrane on top of the ARDEX layer?
This is what I had in mind in terms of the layers on the floor:

------- Tiles -------
------- Underfloor heating mats -------
------- Membrane? -------
------- Marine board / Wetroom tray -------
------- MDF -------

d) Even though I am getting ceramic (non porous) Mosaic tiles for the floor would it
be advisable or even possible to seal them as well?

Maybe I am just paranoid when it comes to Wetroom leakage but I want to make sure
the job gets done right whilst I have a chance

Any thoughts/comments are most welcome!

Cheers,
Manuel

Meant to include a picture as well:IMG_0597-small.jpg

Looks about right though I tend to be belt and braces about these things and will cover the whole floor including the tray with the compound and in the immediate shower area go up to a metre up the walls.

Your ceramic tiles should have a very low porosity and will not seal like natural stone or the cheaper Chinese porcelain. An additional membrane will be overkill unless the floor and particularly the joints is properly tanked. Adhesive and grout must be flexible and it's probably a good idea to use silicone on the horizontal and vertical joints after grouting as there can be a small amount of movement in the new walls as the timber acclimatises causing hairline cracks.

One other thing I have also come across is where kids are involved and its a small wetroom, there is the chance that they will cause the water to build up in the room and it has been known to escape out of the door! Towels, scrunchies or flannels dropped will do this especially if the trap isnt regularly cleaned and hair builds up slowing the drainage flow. A 5mm or so thresh on the door will stop this.

Good luck

Great thanks for your quick reply Spooner! I should have mentioned that they are by no means finished so I'll make sure they cover the whole floor with the Ardex stuff.

As for the grout I am actually thinking of asking them to use Epoxy grout although they might not like the idea