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]

I think I need to keep ripping out…including the floorboards and a lot of the plasterboard… till all I have is the top of the beams, and I can see the rock wool of the lagging that is between the beams in the ceiling downstairs (I have boarded between the beams downstairs since the picture of the bare beams).

Then I can reroute the electrical up into the wall - cutting, lengthening and rejoining - to get them up into the studwork of the end wall without having any cross the beams and messing up my floor.

The I shim the beams, and start afresh with 25mm ply across the whole floor. That should allow a second layer of 25mm ply and still keep me low enough for the shower pan. I can build up with yet more ply on the rest of the floor area (it is not a big room…).

Removing the floorboards may also help me move the evacuation. If I can get it in the middle of the end wall I can use a 180 length wedi pan (cut to 170cm), with the slope leading to a linear drain in the end wall, which will look neat and makes a lot fewer cuts when tiling.

My remaining worry is how to support the ply off to the right, where it is well off the beam… but if I glue a filler piece between the top of the new ply floor, and the underneath of the old chipboard that remains beneath the rail of the stud wall… 🤔

Is this the best way?

 

[Givey Tago]

 

[Givey Tago]

 

[Givey Tago]

I am happy with what I now have as a subfloor. All the wiring has been re-routed, 22mm plywood has been shimmed, and I have a very solid basis off the 3 beams (each of which is 25cm square...). In the end I kept the floorboards as they are about 40mm thick themselves and with everything screwed down, they give further integrity. The subfloor is rock-solid and I have the waste where I want it. The plywood sheets are a little lipped (2-3mm) in parts and I shall plane-down and maybe use a few millimetres of self-leveller too.

So my remaining questions! I am using a 1000x1000x50mm deep Wedi riolitio neo tray, and the rest of the floor will be 50mm wedi panels. The wedi installation says to use 600mm wide fibre-glass reinforcement strips on flooring... But, I want to install electric UFH prior to tile throughout (on the showertray too).

What is the best way to go from here? Glass-fibre, then stick down a mat, then SLC, then tile? Or Ditra-Heat straight on the Wedi..?

Thanks for any suggestions!

 

[Lou]

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

 

[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?