Waterproofing options for new shower room - Tile Advice

[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!

 

[Canttilefortoffee]

i have to ask but are u planning on installing a wetroom in a stone house?...yourself like?

 

[Canttilefortoffee]

anyway, having not seen the room the first issue is deflection...pull up the chipboard and bin it... see how your joists are hung...and if they are cemented in as i imagine..make sure that is tight as...go wrong here....its a faliure...

 

[Givey Tago]

anyway, having not seen the room the first issue is deflection...pull up the chipboard and bin it... see how your joists are hung...and if they are cemented in as i imagine..make sure that is tight as...go wrong here....its a faliure...

Thanks… yes, I am back there at the weekend so will have a look and take some photos. If it looks technically to be a nightmare then I guess a curb takes out a lot of the ballache?

The thing that is bugging me - whatever I do - is how I set the heating mat on the shower preslope. My brain was fried when I made the original post as I will be putting the mat on the cement board face of the Wedi (not onto polystyrene). But I can’t self-level as I would on the floor, because it will be sloping. The mat manufactures say to bed it in thinset, then later to tile onto that. Presumably another option is to make stiff self-leveller and work it in place till set?!

 

[Canttilefortoffee]

Thanks… yes, I am back there at the weekend so will have a look and take some photos. If it looks technically to be a nightmare then I guess a curb takes out a lot of the ballache?

The thing that is bugging me - whatever I do - is how I set the heating mat on the shower preslope. My brain was fried when I made the original post as I will be putting the mat on the cement board face of the Wedi (not onto polystyrene). But I can’t self-level as I would on the floor, because it will be sloping. The mat manufactures say to bed it in thinset, then later to tile onto that. Presumably another option is to make stiff self-leveller and work it in place till set?!

from, what i read u have a plan..but those plans dont include a bad substrate etc..i will read it properly when u add pics and show everyone what the chipboard is hiding...also if the joists are not tied together "i call them "noggins"".. i would add those also...at about 600mm ce3ntres and on the edges of any ply u put down...also..dont skimp on the ply... get marine even tho u are covering it...(most marine ply is made in brazil and has a spec.. standard ply is mostly made in chimna and not from hardwoods so it delaminates...) thats all i got for ya at the mo... good luck bro!

 

[Canttilefortoffee]

Thanks… yes, I am back there at the weekend so will have a look and take some photos. If it looks technically to be a nightmare then I guess a curb takes out a lot of the ballache?

The thing that is bugging me - whatever I do - is how I set the heating mat on the shower preslope. My brain was fried when I made the original post as I will be putting the mat on the cement board face of the Wedi (not onto polystyrene). But I can’t self-level as I would on the floor, because it will be sloping. The mat manufactures say to bed it in thinset, then later to tile onto that. Presumably another option is to make stiff self-leveller and work it in place till set?!

well... tou have yo remove the wire from the backing..so u have some looose wore at some poin in the mat.. as in lay the whole floor first make the loose part for the shower tray (where is most sensible..could be in the middle (do not have the end in the showet its about 5mm ..wire 2mm!) yhen arrange th wire in a snail fashion and avoid the dran square by 150mm or 6" if ya like old money.. once u have planned whewre the wire goes with a few new stanly blades mace a 2mm deep slice... and force the wire into thew gap!!!...skin with addy or thinset if ya over the pond.. for bullet proof add.. getr an S2 standard..heat/wedi board/porcelain tiles/decouplers all need to stay down....but im guessing rthat u are having a go for the first time.... in my experience peoplke usuall end up with a second wetroom for free..... nthe room its leaking into downstairs~!!!"

batterie3s must be dying..bad spelling..but u get the point i hope!

 

[Givey Tago]

 

[Givey Tago]

So it is interesting!

The beams (shown from below in 1 picture) are about 25cm square, with approx. 65cm centres. So the gap between is around 40cm (in places up to 46).

In the planned shower room, the upstairs oak floorboards remain in place (again seen in the photo from below). Whoever built it has suspended a 22mm chipboard floor, on 4x1s, which are themselves shimmed off the floorboards.

Weirdly the wall to the right (as you look into the room) is not over a beam, it is on the chipboard over a void. I have not chopped out all the floor yet… 🤣

 

[Givey Tago]

My plan…

Chop out the chipboard in sections - packing under any areas of stud wall that are sitting on chipboard that is not directly over a beam. They are non weight bearing walls and the oak floorboards beneath are sturdy. Plus I will need some support to for the edge of the new ply floor which will otherwise be 20cm off the beam.

Then rip up all the existing shimming/4x1… to basically start again.

Currently the floor is suspended around 4” off the floorboards to the left, and 4.5” on the right (it is an old house…). I need to raise enough to give room for the electrics to run (you can see them poking out through the floorboards in one picture)… but I can still loose a lot of height, especially for a curb less shower tray, but for the rest of the floor too (giving me room to used wedi, heat mat, self leveller, thinset and tile and still be at the right height for a carpet threshold at the door).

I need to think about heights…. And see where I can move the evacuation too for more drainage options.

Any suggestions welcome. I suppose I will need to noggin the new subfloor to make it even sturdier for the plywood?

 

[Givey Tago]

 

[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!