Tiling Over Underfloor Heating

Tiling Over Underfloor Heating

I wonder if you guys can give me some advice please?

Currently my kitchen floor consists of a concrete sub floor overlayed with 9mm insulation board, warmup loose wire ufh element and then flexi adhesive and ceramic tiles around 6-8mm thick. The question I have is, can I save the ufh by simply tiling over the existing tiles? I will probably be using a thin limestone flag tile around 10mm thick and am hoping that the heat will still be felt through the new tiles.

I am aware that the best option would be to rip the old floor up but I would really like not to have to pay out for new ufh and insulation board again as it has only been down 3 years…..the wife fancies a change!!!!!

Thanks in advance.

I had a similar thing in my kitchen. Screed floor, Insulation boards, UFH wires and the floor was tiled. 6 months later wife said ” don’t like the tiles ” so went straight over with a 10mm porcelain. 7 years later all good, no problem with the heat coming through at all.
If i was going over with a stone, then yes i would use a uncoupling membrane, this would not stop any heat coming up.
So from personal experience you will have no problem at all, just let her pick the tile so there is no come back on you

Hi all, i am just about to spend a lot of my hard earned on having underfloor heating and tiled floor in my kitchen-diner. I always leave these jobs to the professionals but like to educate myself a little to avoid being taken for a mug. Once the underfloor heating is laid in a self leveling latex type stuff what method would you use with the tile adhesive? should i expect complete coverage under the tile or can you use a lump in each corner and one in the middle? sorry for the layman description but all help would be most welcome. Many Thanks, Steve.

If your fixing a thin limestone onto an existing tiled floor with ufh then a decoupling membrane would be required and the heat would struggle to get thru those layers.

You know where this going, rip out IMO

Hi Steve, if you registered with the forums, we would be better able to keep track of your query regarding further questions and answers.


I assume you are talking electric UFH here? It is normal to lay the heating mats on insulating backerboards first of all. Then, I always lay self smoothing compound on the top to protect the cables and give a better surface for tiling on to. Adhesive should be laid to provide a solid bed underneath the tiles. Dabs in the corners and centre of the tiles ARE NOT acceptable!

Dont use dot and dab. If you do the tiles will sound hollow, they will be prone to breakages and infestation of insects etc.
Lay the UFH and either as Grumpy states SLC over the top and tile at a later stage. Or you could tile straight over the UFH but this can be tricky as you may damage the UFH elements. Using a plastic notched trowel will help if you choose the later method.
I would go with Grumpy and Lay UFH and then SLC. Better job in my opinion. You only need to cover the UFH with SLC as the more SLC the harder teh UFH has to work to get heat up to the tiles.
When laying i would spread the floor with a notched trowel and depending on the tile chosen you may find buttering the back of the tile will be needed too.