First shower project

[Luke Redpath]

Hello there. We've just bought our first home and having moved in last week, we are about to start a small refurbishment project on our downstairs WC/shower room.

The existing shower is in a bad way and isn't really useable. Its clearly leaking (a line of blown plaster on dividing wall between shower at tray height) and its obvious why - the "tray" is a custom tiled job and the grout is knackered or completely missing in places. Why the previous owners continued to use it in this state I have no idea. They appear to have tried to fix it by squirting tons of Silicon wherever they can which clearly isn't going to help.

So we've decided to rip it all out and start again. The shower itself is OK as is the Merlyn sliding door and frame which just needs a good clean and de-limescale so we hope to re-use those.

My father in law is an experienced tiler and will be doing the tiling for us.

I've spent ages researching our different options and think I now have a basic plan which I was hoping somebody here could validate and make sure I'm not going to do something stupid. The width of the shower alcove is 104cm which annoyingly means any shower tray is going to be either too short or too long. I'd prefer to avoid building out the wall or chasing in the tray so the plan is to do a custom tiled tray on a plinth (to accommodate waste - the sub-floor is concrete).

My current thinking is:

* Construct plinth out of treated 2x4, board over top with 18mm exterior grade ply, cut hole for waste.
* Line walls of shower with suitable water resistant/proof tile backer board - there seems to be lots of options here - up to similar height as existing tiles (about 1ft down from ceiling)
* Line front of plinth with tile backer board, then fix Marmox showlerlay to top of plinth
* Tape all joints using suitable waterproof tape
* Tile walls, tile tray (FIL recommends using mosaic tiles for tray, I'm aware these need to be at least 50x50mm for Showerlay)

We also plan to replace the existing sink with a slimline vanity unit, fit a new towel rail (current one is too big and rusting) and I'm quite keen to replace the toilet with a concealed cistern/back to wall toilet, perhaps even a wall hung one.

So first of all, does this seem a reasonable plan? I have a few questions:

* Assuming the above plan is reasonable, is it also necessary to tank the shower? We aren't having a wet room as we are keeping the sliding door. Will the waterproof tape across all joints be sufficient?
* If its worth tanking, any thoughts on liquid tanking like the BAL kit vs membrane (Schulter Kerdi, Homelux or similar)?
* We don't know what the the floor is like under the existing tiles but assuming its boarded with ply, is it worth covering this with waterproof backer board, taped up where it meets the shower step? I'm not sure this is necessary and would be concerned about floor height.

Is there anything I haven't thought of? Any options I've overlooked? I realise my FIL could probably answer some of these questions but he's a bit busy right now. He did mention to my wife that Wedi boards are good but their pre-formed tileable shower bases seem to be much more expensive compared to Marmox.

Thanks!

 

[Qwerty]

Hi Luke. Your plans are pretty sound to be honest.
I personally like to build the frame and sort pipework first then dry fit the ply on top. I then cut the showerlay to size and lay this down and mark the waste position on the ply and cut it out. I then fix the ply and then the showerlay. I then fix the wall boards (I use Marmox) so it sits on the tray but it can be done either way to be honest. I then tank the board joins and 90' joins with the showerlay using tape & gum. Again my choice here is Mapei mapegum or aquadefense.
And yes, 50x50 mosaics are the smallest on the showerlay.
You still treat the prep as if you are fitting a wet room, just on a smaller scale really.
Does this help? [emoji106]

 

[Luke Redpath]

Thanks Geoff. That's really helpful. I can see how sitting the boards on to the tray might be a bit easier.

Is there any particular reason you prefer one of those liquid tanking products over the Marmox waterproof tape?

Regarding the wall boards, is there any particular thickness you recommend and can they be fixed with adhesive to both stud and external walls? Does the quality of the wall affect this?

Finally, is it ok to just board the floor of the rest of the cloakroom with ply? Thanks again.

 

[Luke Redpath]

I think I misread your post - so you tape and then tank using the liquid stuff?

 

[Qwerty]

I use Mapei tape with the gum, it's not a self adhesive tape like some.
As for the boards, 10mm minimum for both. Look at the Marmox site for full details ....it's quite informative. Adhesive & plug & screw (with washers) on solid walls and just screw with washers on stud.
I would use tanking tile backer boards on the ply floor. You can use a 4 or 6mm board here [emoji106]

 

[Luke Redpath]

Just wanted to say thanks again for the tips. I've had some discussion on Twitter with Marmox and they recommended 12.5mm on the walls which means I can fix using dot and dab - might be useful for evening out the walls - but more importantly as the shower door is 1000mm and the alcove width is 1047, having 12.5mm backer on each wall and allowing for 10mm on each side for tile/adhesive means the door will fit with at most 1mm on each side, which can be sealed using sealant.

I'll use the thinnest board I can get away with for the floor and front of the shower plinth.

 

[Luke Redpath]

Here's a few models from Sketchup (I find this very good for visualisation and planning measurements):

Lined and ready to tile:


With tiles (just using stock materials in Sketchup), door and furniture:

 

[Luke Redpath]

One more quick question, there are exposed edges along the tops and edges like this:



With the 12.5mm board and assuming approx. 10mm for tiles and adhesive, that leaves a 22.5mm edge to cover. Would you use edge trim for this or would you actually cut tiles and use those?

 

[WetSaw]

Board the whole wall and then just trim the tile.

 

[Luke Redpath]

Wouldn't I then need to get the rest skimmed?

I am wondering if it might just be simpler to board out just the shower cubicle and tile straight on to the wall for the rest of the bathroom as the rest of the room won't actually be getting wet.