Wetroom novice - floor height problems

[Jimbohotpants]

Hi all, I'm new to this wetroom game, and indeed the tiling game, so please go easy on me!

My problem is this: I have a Victorian house with old, gappy floorboards of approx. 20mm thickness. My original plan was to remove these entirely and lay 18mm exterior ply, then 10mm Orbry backer board, then 2mm Orbry Permalayer decoupling membrane, followed by 4mm electric underfloor heating, self-levelling compound and finally tiles. This would all be for the majority of the floor, with an Orbry 30mm former for the actual wetroom shower area. Apart from the fact I have no clue whether this Orbry stuff is any good or not (please let me know if you do!), it gives a total floor height of around 45mm. this isn't too bad considering the UFH ans SLC will be in the former too, so those heights should match, but the height of the carpet in the next room is only about 10mm off the floorboards, so total height of ~30mm. this clearly gives about 15mm difference in floor heights. How should I deal with this? Any ideas?
I've thought of removing the backer boards from the list and using just the decoupling membrane, and going for a narrower former (e.g. Marmox do a 20mm one), but is that a good plan? Essentially I need a total floor height of around 30mm, including tiles. How would you go about this?

I could really do with some help with this so anything you can do would be great!

Cheers,
James

 

[bugs183]

Hiya Jimbo HP!

Designing and building a wetroom can be a real challenge, no way near as easy as people assume.

The height difference between rooms can be a problem, there are no quick ways round it and it depends on the strength and size of your joists, the size of the room, what drain you are using and how your drain pipe work is plumbed.

If you joists are sound with NO movement anywhere, some guys lower the floor by fixing ply wood up flush to the top of the joists, Schluter make a system in their Kerdi range that the pre formed shower tray will fit on top of this.

Schluter products are brilliant and work perfectly, every time, you can phone their technical dept and they'll give you a full spec on what to do. I've not used Orbry, so i can't comment.

 

[trevortine]

Or like this with the wedi former.

 

[Jimbohotpants]

Hi Bugs,
Yeah it's definitely more complicated than it seems at first!
The joists are 2"x4" and the room is 2.4m x 2.7m, 2.3m high.
I've attached a picture to show the layout. You can hopefully see that the first joist is about 70mm from the wall to centre, then the spacing is 360mm between centres. The wetroom area, which is intended to be screened off slightly, is 1200mm x 800mm (desired), and you should be able to see this in the bottom right hand corner of the sketch. You should also be able to see the joist direction. I'm drilling through the exterior wall (right) for the drain, so it doesn't really matter where the drain goes so long as it's between the joists.
The joists are sturdy and I can't detect any movement, but it is an old house and I'm in no way experienced in looking for floor movement! Fitting the ply flush sounds like it could be a goer I guess, but is it risky with these old joists?

trevor, that's exactly the sort of thing I was planning for the former, but even so it'll have UFH and tiles on top, so the total height could be an issue (the tiles are 10mm thick so that + UFH + former (20mm) = 34mm). I notice Shluter do some ramps which might compensate for height differences, anyone used them? Are they any good?

Thanks again for your help, it really is appreciated!

By the way, I live inCamberley, surrey, and will be after someone to do the actual tiling (walls and floor), once I've got the SLC down, so if anyone's interested let me know!

James

 

[Jimbohotpants]

 

[Jimbohotpants]

Anyone? What about those Schluter ramps? Orbry? Any good? Any advice would be helpful (the advice above is already helpful, but more would be nice )

 

[bugs183]

Sorry mate, been doing other stuff.
I've not heard of Orbry, so i can't comment. As for the ramps i've got a mate whose a joiner and he makes hardwood threashold strips for me, i give him the length, thickness and depth, and whether i want bull nose edges and it works a treat.
It's really hard to advise on the work that would need to be done as you could pull the floor up and find anything under there, joist thickness, previous trades making holes where they shouldn't etc.

 

[Jimbohotpants]

No worries fella.
The carpet's already been laid almost into the bathroom so I think the wood option wouldn't work, which is a shame cos it sounds good! I think those ramps from Shluter look like the best option for now, and unless anyone has any objections to me laying 18mm ply, then the tanking/decoupling membrane straight on top (no backer board), then I'm going to go with that. This should give me about 4mm difference in floor height (I think :/).
I've had a lot of the floor up already to do some other plumbing and lighting for the kitchen (spotlights - the kitchen is directly below), and the joists seem pretty sound and regular. There are some holes drilled through them for wires and things from the past, but nothing that looks major, and no chiselled top edges that I could see. All the old plumbing is above the floor.

Again, thanks for the advice.