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Housing - New Build: Floor Tiling (again!)

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  1.  
    • CommentAuthorCerisy
    • CommentTimeAug 28th 2015
     
    We are about to start on the floor tiling in the en-suite. Spec is tiling adhesive, slip membrane, heated mat, adhesive and topped with tiles. Pretty standard - well, apart from the tiles being 50 x 50 cm!

    It's a relatively small room - 4 sq m heated mat - so not too many tiles to lay, but I just wanted to check the best way to lay the sods! As with our large floor tiles downstairs, I'll back butter the tiles, but as I lay the top layer of adhesive can I use the notched trowel (very carefully of course) to try and get it level or should I go for full bed contact?

    I don't have a deadline this time, so I can take my time - so any suggestions, even if they mean doing one tile a day, would be appreciated!

    Many thanks, Jonathan
    • CommentAuthorowlman
    • CommentTimeAug 28th 2015
     
    Slip membrane? do you mean decoupling membrane?
    • CommentAuthorowlman
    • CommentTimeAug 28th 2015
     
    Electric heated mats, (presumably), usually require insulation beneath you don't mention that.
    • CommentAuthorCerisy
    • CommentTimeAug 28th 2015
     
    Thanks Owlman - yes, decoupling membrane - sign of old age creeping in!

    Not too worried about insulation directly under the heating mats. The basic floor is structural chipboard, installed as part of the frame, and the ceiling below is heavily insulated. Any small heat loss downwards will simply add the the overall comfort - yes, we have MVHR, etc, etc!!

    Regards, Jonathan
    • CommentAuthorowlman
    • CommentTimeAug 28th 2015
     
    Most decoupling membranes are glued to the substrate. Whilst they do the job, ( as decouplers ) the adhesive makes them act as part of the structure. As a rule of thumb chipboard is a no/no in wet rooms, despite it's widespread IMO very bad use, Ply is a much preferred material. Water can eventually penetrate the grout lines. That said, ideally, you need to isolate the tile from the floor.
    Cement faced insulation boards can do this and give you a more efficient U/F heating. I hear what you say about it all being within the envelope etc.. But what presumably you're after is the warm underfoot feel, and it's not helping if you're dispersing that heat, albeit in a good way.
    There are Decouplers on the market where you don't stick them to the substrate, instead, letting them and the tiles " Float ".
  6.  
    Posted By: owlmanMost decoupling membranes are glued to the substrate. Whilst they do the job, ( as decouplers ) the adhesive makes them act as part of the structure.


    I don't think this is how they work. Ditra, for example, has a fleece side that's cemented (you never use glue) to the substrate. My understanding is that the fibres of the fleece provide the flexibility between the two different materials and essentially perform the decoupling. As ditra is waterproof, there is no worry about moisture transfer through the grout lines (which does happen, no matter how much you waterproof the grout (though epoxy is probably OK).

    Paul in Montreal.
    • CommentAuthorowlman
    • CommentTimeAug 28th 2015
     
    I was using glueing in the widest sense, Paul, I meant with tile adhesive. The fleece provides the adhesion to the smooth plastic but with a breakable joint. AFAIK it's not a movement joint.
  8.  
    Posted By: owlmanI was using glueing in the widest sense, Paul, I meant with tile adhesive. The fleece provides the adhesion to the smooth plastic but with a breakable joint. AFAIK it's not a movement joint.


    Yes, I think you're right.

    This is what it says on the ditra website:

    "Schluter-DITRA provides uncoupling through its open rib structure, which allows for in-plane movement that effectively neutralizes the differential movement stresses between the substrate and the tile, thus eliminating the major cause of cracking and delaminating of the tiled surface.

    Schluter-DITRA provides reliable waterproofing in interior and exterior applications. Its polyethylene composition protects the substrate from moisture penetration, which is particularly important in today’s building environment where most substrates are moisture sensitive.

    The distinguishing feature of Schluter-DITRA is the existence of free space created by the configured channels on the underside of the matting. The free space provides an escape route for excess moisture and vapor that could otherwise cause damage to the tile layer above. Thus, DITRA effectively manages moisture beneath the tile covering."

    Movement joints are still needed though AFAIK.

    Paul in Montreal.
  9.  
    My bathroom floors are chipboard. I fitted cement fibre board fitted to chipboard with tile adhesive and screws as (stainless) per instructions. Then just tile on the other face of the cement board as required.

    I am totally happy as I have zero cracks in 3 bathrooms. All floors are tiled and have been down 3 years.

    I did use a very good tile adhesive though and I will never use the cheap stuff again.
  10.  
    We've just laid an overlay wet underfloor (Fermac boards routed out for the pipe - Wundafloor) over Eggerboard. On top of that went Ditra stuck down with Mapei Keraquick. Tiles on top went down with Keraquick with Latex.

    Neither room is actually a wet room (we've a flush shower tray in the en suite/shower over bath in the bathroom).

    Floor tiles were 600x600, wall tiles 1200x600 porcelain. Just finished grouting this afternoon and hung the toilets - it's been one hell of a job. Still have the ground floor toilet to go.....
    • CommentAuthorCerisy
    • CommentTimeSep 2nd 2015
     
    Simon - how did you lay the big floor tiles? Full bed or notched trowel? Slightly concerned at possible issues with air under the tiles and the underfloor electric heating, but some guidance would be appreciated.

    Thanks, regards, Jonathan

    PS Makes my worries over the 500x500 floor tiles and 300x700 wall tiles seem insignificant!
  12.  
    We used a 10mm notched trowel and back buttered. On the floor the weight of the tiles alone bedded them in well. My understanding is you use a 10mm notched trowel to give a 5mm solid bed after compression.

    On the walls it was difficult and I suspect we will have some voids but can't see them being an issue -
    •  
      CommentAuthordjh
    • CommentTimeSep 3rd 2015
     
    Posted By: Simon StillMy understanding is you use a 10mm notched trowel to give a 5mm solid bed after compression.

    That's my understanding too.
    • CommentAuthorCerisy
    • CommentTimeSep 3rd 2015
     
    Thanks Simon - I'll start in the morning!!

    Regards, Jonathan
    • CommentAuthorCerisy
    • CommentTimeSep 9th 2015
     
    Floor tiles all done yesterday - only 20 tiles, but at 50 cm sq they were a little tricky to lay!

    Leaving them for the full 24 hours to allow the adhesive to harden, then it's big wall tiles to move onto.

    Photo attached - regards, Jonathan
      DSC_2506.jpg
    •  
      CommentAuthordjh
    • CommentTimeSep 9th 2015
     
    Looks good to me.
    • CommentAuthorDandJ
    • CommentTimeSep 16th 2015
     
    On the Ditra subject:

    "The distinguishing feature of Schluter-DITRA is the existence of free space created by the configured channels on the underside of the matting. The free space provides an escape route for excess moisture and vapor that could otherwise cause damage to the tile layer above. Thus, DITRA effectively manages moisture beneath the tile covering."

    Does the existence of 'free space' mean that there are air pockets under the tiles and doesn't this mean less efficient heat transfer from the UFH. Just trying to sort out how to do mine.
    • CommentAuthorowlman
    • CommentTimeSep 17th 2015
     
    Is it a concrete, or other solid floor?

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