Wetroom floor buildup

[Workerbee]

Hello - I was wondering if you'd be able to sense-check my floating floor plan, please? 

 

The wetroom is just a corner of the bedroom, about 3.7sqm. In the bedroom, I'll be putting 50mm PIR on the slab, topped with 22mm chipboard. For the wetroom floor, I therefore thought I'd do the same, then topped with impey waterguard, electric ufh, and natural stone.

 

To help with stability on the floating floor, I thought I could add a perimeter of battens like in the picture below, and screw the chipboard into it: 

 

Does this sound like a plan?

 

Thank you.

[Nestor]

Floating so battens not fixed to the slab?

 

Edited 6 hours ago by Nestor

[Nickfromwales]

You're either floating or not. Fixing the chipboard to the battens would cause a conflict.

 

Why floating? Seems added uncertainty with a mixture of bedroom > bathroom wetroom flooring.

[Nestor]

11 minutes ago, Nickfromwales said:

You're either floating or not. Fixing the chipboard to the battens would cause a conflict.

 

Why floating? Seems added uncertainty with a mixture of bedroom > bathroom wetroom flooring.

What Nick said,

A tiled floating floor wet room does not work for me, I would want it all fixed with zero movement.

When I tiled our wet room I fixed Hardie backer board through to the P5 Caberdek which is fixed to the floor joists.

Edited 5 hours ago by Nestor

[Workerbee]

Thank you both. It's a renovation that previously had 50mm polystyrene on the slab, topped with 22mm chipboard, so I don't feel I have much choice about it being floating. My thinking was that the battens would provide more stability for tiling. I would screw the battens to the slab, then screw the chipboard to the battens.

 

I'd originally thought about XPS tile backer boards adhesively stuck to the slab, but manufacturers seemed to think tongue and groove was essential. 

 

Would there be a better way, do you think?

[Nickfromwales]

14 minutes ago, Workerbee said:

Thank you both. It's a renovation that previously had 50mm polystyrene on the slab, topped with 22mm chipboard, so I don't feel I have much choice about it being floating. My thinking was that the battens would provide more stability for tiling. I would screw the battens to the slab, then screw the chipboard to the battens.

 

I'd originally thought about XPS tile backer boards adhesively stuck to the slab, but manufacturers seemed to think tongue and groove was essential. 

 

Would there be a better way, do you think?

Yes. Stop listening to the manufacturers and go with the bonded XPS (Wedi / Jackoboard) type material. 
 

You’ll need to self level over them as they follow to subfloor, but that’s your opportunity to bury the electric UFH. 👍

 

Then tank and tile. 

[Workerbee]

Thank you for your help with this. My two worries about that would be the low amount of insulation for the electric ufh (xps a worse insulator and the self levelling eating into an already shallow buildup), and that when the ufh breaks, I'd need to cut into the tanking and self levelling, not just the tiles.

 

Would the chipboard idea (either with battens, or without and bonded to the slab) definitely not work? I'd also looked at gypdeck 18, but it's expensive and presumably wouldn't connect into the 22mm bedroom chipboard.

[Nestor]

Some random thoughts, not a professional but built a house with 4 bathrooms.

A  level threshold to the bedroom would be very critical for me, within a few mm.

 

I fitted wet UFH in foiled EPS boards under the 6mm Hardie Backer and electric cable in a 50mm sand & cement screed.

 

You could use 18mm P5 or 12mm Hardie Backer above the insulation and slab but would need to be fixed well, no movement.

 

I think fixed battens to the slab would work.

 

Electric, (is it self adhesive matting) fitted to one of the above then apply thin layer of self levelling to encapsulate heating elements.

Then tank and tile.

 

What the Boss @Nickfromwales said.