Best adhesive for marble tiles with UFH - Tile Advice

[Tile_novice]

Hi guys,

Any opinion on the best adhesive used with wet UFH for marble tiles?
Also any advice on tiling over an existing porcelein floor with electric UFH - did want to rip it up and start fresh but the tiled surface is very solid, so felt tiling straight over would be good (and wouldn't have to get new UFH). Opinions would be appreciated - I know the flat surface may make adhesion difficult, have thought about scoring the surface of the existing tiles.

Thanks in advance.

 

[hmtiling]

For the marble you'll want a decoupling membrane or a crack mat at least and use an s1 white rapid or semi rapid.
For over tiling porcelain prime with a mechanical grip primer like isomat supergrund and I'd go s1 again. Providing floor is sound

 

[WetSaw]

Not sure how efficient ufh will be under 2 layers of tiles.

 

[hmtiling]

Not sure how efficient ufh will be under 2 layers of tiles.

I'm not sure how much difference it will make. Heat up time will be longer but won't it just act as thermal mass?

 

[WetSaw]

Potentially, but I suppose that would depend on the original installation, adhesive depth etc.

 

[Tile_novice]

For the marble you'll want a decoupling membrane or a crack mat at least and use an s1 white rapid or semi rapid.
For over tiling porcelain prime with a mechanical grip primer like isomat supergrund and I'd go s1 again. Providing floor is sound

Many thanks for that I do appreciate it - would a decoupling membrane be needed even if using a backer board like Hardie? Also I always thought that a slow setting flexi adhesive would be used - could you enlighten me on why rapid or semi rapid would be used (you’re far more experienced then a DIy’er like myself so I appreciate your insight).
Thank you for the advice on Porcelein - have you tiled over existing UFH tiled surface before?

Thanks

 

[Tile_novice]

Not sure how efficient ufh will be under 2 layers of tiles.

At present it’s very warm so the added heat up time is fine with me.

 

[hmtiling]

Many thanks for that I do appreciate it - would a decoupling membrane be needed even if using a backer board like Hardie? Also I always thought that a slow setting flexi adhesive would be used - could you enlighten me on why rapid or semi rapid would be used (you’re far more experienced then a DIy’er like myself so I appreciate your insight).
Thank you for the advice on Porcelein - have you tiled over existing UFH tiled surface before?

Thanks

Are these both timber floors?

 

[Tile_novice]

Are these both timber floors?

Its funny you mention that - its another debate im having at present! At present its a suspended timber floor with the insulation, UFH pipes covered in 50mm screed. Debating on whether to cover it in 18mm WBP ply then hardie board, or whether to do a layer of 12mm hardie board, followed by 6mm hardie board then tile straight on to it (may put decoupling membrane on top of final hardie board layer). These are all options at present but im open to suggestions.

 

[hmtiling]

I assumed this was a solid floor.

 

[hmtiling]

.

 

[Tile_novice]

I assumed this was a solid floor.

Nope it isn't solid concrete - joists with 50mm insulation in between UFH, then screed layer.