Urgent help needed please

[Tile_novice]

Hi guys,

I would really appreciate your advice.
Some background - suspended wooden floor, 50mm insulation between, UFH, 50mm screed level with joist level & covered in 18mm WBP plywood (not securely fitted at present yet). UFH has been running on the lowest setting for several weeks and screed is dry,
Now don't want to get into the debate on using wood in UFH (I understand the deflection aspect etc, but I had no real choice in this situation - going for full concrete floor would be an arm and a leg because the ground level is 3 foot below the suspended floor!)
The tiles to be used are marble.
Now heres the dilemma - do I overboard with 6mm hardie, then use the SLC, then tile - or do I do the reverse
OR do I go straight over the ply with the SLC, then Ditra then tile
OR does anyone wiser and more experienced then me have any suggestions.

Also have been advised to use an S1 semi rapid adhesive for the marble - was going for the tilemaster setaflex.

Cheers in advance

 

[Andy Allen]

Can't make out your set up ...
Is it a floating floor...??

 

[Tile_novice]

Can't make out your set up ...
Is it a floating floor...??

Sorry yes with floor joists sitting as per original 1930’s construction.

 

[Andy Allen]

Marble tiles are very soft and the floor would need to be deflection free..

If it is a floating floor I personally wouldn't tile it..

 

[Tile_novice]

Marble tiles are very soft and the floor would need to be deflection free..

If it is a floating floor I personally wouldn't tile it..

I have no option I already have the 70 square meters,

 

[Tile_novice]

I have no option I already have the 70 square meters,

I was assuming the hardie would assist in strengthening as well

 

[Andy Allen]

How much deflection is there...?
Is it very 'bouncy'...

 

[Tile_novice]

How much deflection is there...?
Is it very 'bouncy'...

Not a lot of bounce to be fair

 

[Andy Allen]

Not much more I can say really...

Imo 70m of marble tiles on to a floating floor with ufh is a disaster waiting to happen..

Someone else may be able come up with a solution, but your floor would have to be totally deflection free to prevent the tiles from cracking or de-bonding...

 

[Dumbo]

Are you going to fix the ply to the joists with screws

 

[Andy Allen]

This is what I don't get .....you mentioned joist yet you say it's a floating floor .??

 

[Bathfix Bob]

Suspended....Joists with floorboards, chipboard screwed down.

Floating.....solid screed with layer of insulation and then chipboard laid on top with no screws holding it down.