Continous Tiling onto different sub floors - TilersForums.com

[gontarek]

Hi,

We have just had an extension to our kitchen built. I am wanting to floor tile (probably Tavertine) the existing kitchen area & the extension area as one continous level area.

The problem I have is that the kitchen is suspended wooden floor and the extension is a concrete subfloor that was made level with the existing kitchen floor.

Now I am aware that I have to stiffen the wooden floor with 15mm+ WBP ply ( and of course seal it with PVA before gluing), however how should I bring the concrete subfloor up to the same level ?

I could just continue the plywood sheeting, but I am concerned that this may insulate the floor too much as we have underfloor heating built into the concrete slab: there is also the problem of fixing the sheets to the slab - I don't want to drill into into for for obvious reasons.

Alternatively I could level it by adding more screed - though that would be quite a bit (at least 18mm to bring it up to the plywood level on the kitchen floor).

I would really appreciate any advise on this.

thanks
Steve

 

[pete f]

i would say that you will have no choice the concrete floor will either have to be overboarded or screeded to bring it up to the same level you will also need a de coupling membrane on the suspended floor area to stop lateral movement

 

[smurf21]

hi what you need to do is cover timber floor with 6mm tile backer board (NO more PLY). then a self levelling compound onto the conc floor only needs be 6mm thick. the no more ply at 6mm is better than 18mm plywood and a better surface to tile on
And use an expansion strip between the substrates when you tile.

 

[grumpygrouter]

Hi,

We have just had an extension to our kitchen built. I am wanting to floor tile (probably Tavertine) the existing kitchen area & the extension area as one continous level area.

The problem I have is that the kitchen is suspended wooden floor and the extension is a concrete subfloor that was made level with the existing kitchen floor.

Now I am aware that I have to stiffen the wooden floor with 15mm+ WBP ply ( and of course seal it with PVA before gluing), however how should I bring the concrete subfloor up to the same level ?

I could just continue the plywood sheeting, but I am concerned that this may insulate the floor too much as we have underfloor heating built into the concrete slab: there is also the problem of fixing the sheets to the slab - I don't want to drill into into for for obvious reasons.

Alternatively I could level it by adding more screed - though that would be quite a bit (at least 18mm to bring it up to the plywood level on the kitchen floor).

I would really appreciate any advise on this.

thanks
Steve

Hi Steve welcome to the forums. Firstly, PVA has no place anywhere in a tiling installation. To seal the ply before laying use something like an SBR type primer or polyurethane varnish.

What floor area are we talking about here? is the timber floor solid i.e. minimal deflection or is it quite bouncy?

 

[gontarek]

Hi Steve welcome to the forums. Firstly, PVA has no place anywhere in a tiling installation. To seal the ply before laying use something like an SBR type primer or polyurethane varnish.

What floor area are we talking about here? is the timber floor solid i.e. minimal deflection or is it quite bouncy?

Hi Grumpy, - it is quite a small area - 3.4mx4.4m. The floor, although suspended is alsso supported by floorplates at the sides and done the middle (8x2 joists). The floor certainly doesn't flex too much, but if you stamp your feet, it does vibrate briefly. I did use PVA to seal plywood MArine ply for our shower area several years ago and it seems to be fine.

I'm curious about smurf21's suggestion about tile backer board: I'll have look at that one.



Steve

 

[grumpygrouter]

Me and Smurf have slightly differing ideas about backer board. if you floor is pretty solid then I would def go with the backer board route. I am personally not convinced that 6mm NMP even with the supplied mega adhesive would give equivalent strength to 18mm ply. I have seen no documentary evidence to prove this even though the MD of the UK importers was asked the question in these forums, nothing was forthcoming. Nothing wrong with the product as a backerboard but if it was me, i would make sure the floor was solid first before using it.

 

[smurf21]

I Agree With grumpy in the fact that the floor should be as solid as poss first but that is true before overboarding with any product, NMP is my particular favorite because once treated with SBR it is totally waterproof also if not for the underfloor heating you could have gone str8 over the concrete floor , but given its insulating properties and the heating being in the floor already the NMP would work against you trapping the heat in the floor.

 

[smurf21]

Just out of interest Grumpy have you ever used NO MORE PLy?

 

[grumpygrouter]

Just out of interest Grumpy have you ever used NO MORE PLy?

No Smurf I haven't, though I would like to try it. Can't get it in these remote parts of the world I am afraid. Have to make do with Hardie or Wedi!!

 

[gontarek]

Thanks for your advice GrumyGrouter & Smurf21. Most useful

Steve