UFH - Thermanet - marble tiles onto ply

[edwardk]

Hi everyone - I've boarded out the walls and fitted the shower tray and bath.
I'm keen to get the floor tiled now and was wondering what the best way was.

I've got 12mm pale marble tiles to go down.

The substrate is 18mm t&g flooring ply (I'm planning on fixing it down a bit better as I had to lift sections for pipe work - planning on adding extra noggins where I can and filling any gaps with ply shims and polyurethane glue).

I've bought some Thermanet UFH - it's 150W matting.

So the question is - how should I prepare the floor and add the UFH ready for tiling?

I have been using Marmox for the walls.

Should I add a layer of Marmox over the ply? If so what glue is good and should I screw down with board washers? Is 6mm board ok?

I have Ditra matt left over from the kitchen floor - enough for the bathroom.

I have Ardex x77W for the final marble tile lay.

Is this a good idea ? : ply -> glue/screw -> 6mm Marmox -> ufh glued down -> slc -> ditra -> x77w -> marble

Thanks,
Ed

 

[bugs183]

Tile the walls first, as you could easily damage the floor tiles.
Then lay the floor as you suggest, if the Marmox is glued and screwed well then i wouldn't bother using the Ditra, it's only a small area.

 

[Time's Ran Out]

If you have the Ditra then I'd certainly use it for Marble. With the thermal movement caused by the UFH on a wood substrate the uncoupling properties can only be of benefit to the longevity of the floor.

 

[bugs183]

ooops Timeless is bang on, i missed the marble part, yep use the ditra, and back butter the marble as they can shade from the ridges from the notched trowel.

 

[Uheat - Keith]

Yes, as with Bugs & John above, 6mm Marmox over ply before UFH at 150w/m2-160w/m2.
Powdered flexible tile adhesive under Marmox.
Powdered flexible self-levelling compound over UFH, then Tiling and/or Powdered flexible tile adhesive.

Warm regards, Keith.

 

[edwardk]

Thanks for all the info and advice - much appreciated.

So walls first...
Do you laser level a line around the room at waist height then tile the walls down to the substrate leaving a 10mm gap and then when you do the floor tile up to the wall leaving a 5mm gap?
(I have plastered the walls halfway down from the ceiling)

I'm just keen to get the UFH in so the electrician can finish off and I thought I could do the floor first but it's probably better practice to do the walls first then floor.

So for the floor is this good:

13 - lithofin sealant x 4 coats
12 - grout
11 - marble tile - (finished floor surface)
10 - Ardex x77w (back butter tiles - 6mm trowel)
9 - ditra mat
8 - any quick setting tile adhesive to stick the ditra down - 6mm trowel?
7 - slc
6 - tape or glue down UFH - (tape or polyurethane Gorilla glue ?)
5 - UFH - (Thermanet 150w)
4 - screws and washers through marmox
3 - Marmox 6mm boards
2 - glue down marmox (any tile adhesive ? I think I have some fast setting Ardex grey stuff left over - will any cement based tile addy do ?)
1 - ply prep ??? do I need to add Ardex P51 to the ply before sticking down the Marmox or anything like that?
0 - ply substrate

Main questions:
A - should I tile walls first then floor?
B - what is a good adhesive for sticking 6mm Marmox down?
C - Anything else I've missed that might catch me out ?

 

[edwardk]

Went to the local shop and the guy advised me to do the following:

6 - marble tiles
5 - Ardex x77W
4 - SLC (he sold me Cempolatex)
3 - UFH wires (taped down)
2 - Ditra matting
1 - Ardex AF 200 (to stick Ditra down - work fast / small toothed trowel)
0 - ply substrate

Is this a good idea ?
Thanks,
Ed

 

[Rookery]

I'm not familiar with some of those products but in general I would:
Fix marmox with rapid set flexible adhesive and screws/washers. My preference Mapei Keraquick, 6mm notch trowel
UFH matt/cable held down with gaffer tape.
Flexible SLC. My preference Webber Floorflex.
Fix Ditra with Rapid Set. My preference Mapei Rapid Set, 4mm notch trowel
Fix tiles with rapid set flexible adhesive. My preference Mapei Keraquick, 10mm/13mm notch trowel and back skim each tile too.
Personally, I would tile the floor first.

You say that you've plastered the walls halfway down fron the ceiling. Are you planning to tile these areas with the 12mm marble. If so they are likely to be about 50% over the BS weight limit for plastered walls.

 

[edwardk]

@Rookery - thanks - no, I'm just tiling halfway up the wall for most of the room and then maybe topping off with a chair rail - the top of the wall will remain plastered.
The rest of the full wall height areas are Marmox 12mm board and I was going to use a slightly thinner limestone on them so should be ok.

So the dilemma:
Should I :
A : ply -> ditra -> UFH/SLC -> Marble on the floor
B : ply -> marmox -> UFH/SLC -> Ditra -> Marble on the floor

Which is better ? Am happy to go and swap materials - am doing this myself for my own house so not fussed on the cost as I'll be doing the labour and want a solid job that will last a loooong time
Ed

 

[bugs183]

B!
As the marmox will work well with the ply,and be a good thermal base for the ufh, level over the heating, leave a overnight to dry, add ditra to the top, (even if you use rapid set let this dry overnight too), this will absorb any movement. Tile over this, job done.

 

[Rookery]

B also. Though the Ditra will only cope with some movement and then only lateral movement. You must prepare the subfloor adequately otherwise everything else after is at risk.