Waterproofing options for new shower room

[Givey Tago]

Hi,

A newcomer here and thank you to anyone with the patience to read my drivel.

I am renovating an old stone house, have just finished a kitchen, and now need to install a first floor shower room (1.7m x 2.35m).

The previous owner had the room to a state of green plasterboard walls, and chipboard floor. There are hot and cold feeds to one of the long walls, for a vanity, and hot and cold feeds - and evacuation - to the end wall, for a shower mixer and shower drain.

I have yet to lift the chipboard but think it is installed on very thick (300mm square) beams presumably with shimming.

I want to install a curb less tiled shower across the width of the room (1700mm). This will be partially partitioned by a half-height wall, and a glass screen. I think around 90cm deep leaving 80cm access into the shower. I shall install a vanity along the remainder of the long wall (spanning between the short wall with the door into the room, and the half-height partition wall for the shower). So a simple layout. And I would like to heat the floor and the shower floor. But most of all, I want it watertight!

Cost is always an issue but it is a relatively small room and I am not a pro, so I would rather pay for reliability and ease.

The various systems are driving me crazy and if I watch another YouTube shower video I may lose it altogether 🤣

The main choices appear to be Wedi or Kerdi/Schluter.

My understanding is that I would need to…

1) Take up the chipboard, see what I have, but aim for a level subfloor of 22mm marine ply with the ply dropped between the beams in the shower area to accommodate the tray;
2) With Wedi, panel the shower area and 3ft beyond with 1/2” panels (effectively the whole area as it is a small room) - either over or in place of the plasterboard;
3) Build the partition wall by laminating 2x 1” sheets of Wedi;
4) Deck over the plywood floor with 1/4” Wedi (and plan the shower subfloor so it will still be flush)
5) Install a heat mat on the floor and in the shower;
6) Cover with thinset;
7) Tile floor and then walls.

Have I understood the layers and sequence?
Is Wedi a good option for me or should I be thinking Kerdi/Schluter (I do like the lapping and the reliance of Wedi on caulking seems more error-prone)? Or something else?
Can I apply heat mat direct to the polystyrene shower base?

My thinking is that the Wedi will waterproof everywhere and give me a slip layer above the plywood. I would have no slip layer in the shower but I guess I don’t need one as I am tiling onto the shower tray (over the mat set in thinset).

Thanks for any comments, whether I am on the right lines or missing something vital!

 

[Givey Tago]

Great thread - thanks for keeping us updated. Please show us all the finished job!

Thanks Lou.

Any suggestions as to what layers I need from the Wedi upwards (for a heated floor)?

I think the Wedi will serve as insulation and as a decoupling membrane from the subfloor. But I don't understand why they advise their 600mm glass-fibre reinforcement on floor panels. Presumably to further limit any movement...? But do I still need to use reinforcement if I am laying a heated floor - won't ditra-heat, or a self-adhesive heating mat, do the same thing?

And would you just stick down a self-adhesive heated mat (like warm-on), and set it in self-leveller, prior to tile... Or thinset down some ditra-heat, then self-leveller, then tile?

So my questions - (1) do I still need to use 600mm fibreglass reinforcement if I am laying a heated floor; and (2) would you advise a self-adhesive mat, or ditra-heat, on the cementacious face of the wedi?

Thank you..!

 

[Givey Tago]

Things are coming along. I self-levelled over the 22mm marine ply floor (there was a bit of lippage between the 2 boards and I could afford to bring the height up a bit). The shower went in nicely once I had mortared in the wedi drain. First fix is done, I have panelled all around, I am not too far from tile now once the heating mat is down and embedded in self-leveller.

I may be overthinking this, but my remaining puzzle is around what to do with the heating mat over the shower tray (which is angled a few degrees for drainage). Do I make the self-leveller a bit thicker, use a rapid setting type, and keep scooping it up the hill (if it is running down) till it has begun to set? Or use an entirely different product (I have seen a 'pent' mortar that can be used to make inclines up to 10% e.g. as the mud in the base of a shower.

Could I use self-leveller on the flat floor and some mortar on the tray, then tile over the lot? Or better to use self-leveller throughout and I am worrying too much that it will level the shower tray (which clearly I don't want).

As I say, may be thinking too much here!

Thanks for any suggestions...

 

[Tile Marble Granite]

I like that wooden beam ceiling. Looks good!

 

[Givey Tago]

I like that wooden beam ceiling. Looks good!

Thank you… Any idea what I do with my slope?! 🤣

 

[Tile Marble Granite]

Are you talking about the shower slope?

 

[Givey Tago]

Yes. I am thinking - self-love over the mat on the flat part. No leveller on the slope and just make up the height with thinset..?

 

[Givey Tago]

Autocorrect… agghhh

Self-leveller!!!!!!! 😱

 

[Tile Marble Granite]

The entire floor is level, and you want to create a slope in the shower area? Thought you already pitched down the shower. You will have to rise up the entire floor to be able to get a pitch down in the shower area.

 

[Givey Tago]

No… the floor is flat, the shower area is already sloped (a wedi riolito neo tray with a linear drain up against the wall).

I am putting a heating mat everywhere, including the shower area. And ideally I will bed it in a thin layer of self leveller. But I don’t want to do that on the shower area because I don’t want to level the slope!

I think the answer is: use self leveller on the flat floor (not to level, just to cover the heating mat prior to tiling) - and don’t use leveller on the tray, just make up the height with thinset. Ideally I don’t want a junction between the leveller and something else -beneath the tiles - but I can’t see a better way.

Someone must have put a mat on one of these trays….?!

 

[Tile Marble Granite]

Schluter system would be good for what you are describing over there.

Floor Warming for Shower Floors | Schluter

5 Tips for Installing Floor Warming in your shower. Included is a video showing you how to safely install heat under your shower...

www.schluter.com

 

[Givey Tago]

Thank you. I already have the mat - but perhaps the answer is to embed in thinset and cover with membrane (wedi do a membrane too), so I have a flat and even surface to tile on. And I can use the same technique on the tray as I am not bothering with leveller.

 

[Tile Marble Granite]

Embed the membrane in thinset only, make sure it gets a good bonding.
If the membrane is similar to Schluter then it is easy to install the tiles on top following the manufacturer's instructions.

 

[Givey Tago]

Embed the membrane in thinset only, make sure it gets a good bonding.
If the membrane is similar to Schluter then it is easy to install the tiles on top following the manufacturer's instructions.

Thank you 👍🏼

 

[Tile Marble Granite]

Thank you 👍🏼

Send us some pictures during and after the job is done. Good luck!

 

[Givey Tago]

In the end I put my Big Boy pants on, mixed up some rapid setting leveller, waited 5 minutes, poured it, and raked it back up the slope a few times till I was happy it had set.

I have so many layers going on already I decided against membrane. The mat and leveller are on 50mm wedi board so I am happy there is decoupling.