Wetroom subfloor advice please

[gilesweb]

Hi there,

New to wetrooms and have been reading up on here trying to decide what I need to do for mine. Thanks to all the good advice on loads of threads I think I've got a plan - hoping you can check I'm not about to make a complete mess of it:yikes:

It's a 3.2 x 2 metre room and I'm planning a shower across one of the shorter sides with a Maxxus 1200 x 900 channel deck in the corner and a 1.4 metre screen positioned 1 metre out parallel to the shorter wall forming the enclosure. The other end of the room will have a bath across the other short wall and there will be a wall mounted basin in the middle of the long wall (door is on the other long wall, toilet is next door to the wetroom)

Originally there was 18mm OSB in poor condition over nice chunky joists (75mm x 17cm) at 400mm centres. I've removed this so I'm starting from scratch, hoping to get a nice secure base but not build up too much height so that I can loose it in the transition to carpet in the bedroom.

So thinking of the following for the main part of the room:
18mm WBP ply
6mm HardieBacker
Devi UFH mat/about 5mm SLC

and the Maxxus floor former sitting on 9mm WBP ply to level it up with the rest of the floor.

Then on top of the whole area a membrane (Ditra?) tiled with 10/12mm Travertine.

So am I on the right track or completely nuts!
Any thoughts gratefully received
Giles

 

[White Room]

If your've ripped up the existing floor add some extra noggins to give your ply a bit more support..and under the tray, also for extra support.

Don't butt joint your ply, leave a 2-3mm gap.

Are you tanking the walls, if you are not, you should in the shower area..

I would lay the Devi heat matt on the ply but check if you have to prime the ply, think they supply a primer but check, self level on the heat matt but use some sticky tape to hold the wires down, they could rise up and protude through the slc, I prime the slc and spf addy, ditra on top, then tile with a single flexible adhesive white.

 

[gilesweb]

Hi whitebeam,

Thanks for the advice, will certainly add noggins as you suggest. Sorry if this is a silly question but when you say lay the devi on the ply do you mean not bother with the hardibacker at all or have the devi in between the ply and the hardie?

 

[White Room]

If it's just the heating matt then I would lay on the ply but would that effect your hights..was the hardie there to bring the hights up.

 

[gilesweb]

No I was under the impression that I needed more than 18mm ply to get a stable surface for tiling onto, maybe as two layers rather than one but if that'snot necessary could just go with the ply on its own which leaves me with less of a step up from the bedroom

 

[White Room]

Just remember the extra noggins, you can get thicker ply if works for your hights, about 22mm thick.

Where about in Herts are you.

 

[gilesweb]

OK thanks whitebeam. would you say that one layer of thicker ply is better than 18mm + the HB then?

We're in Ware