tiling around underfloor heating

[alandyman]

my 1st post so please don't be too harsh on me

I'm refitting my kitchen at the moment. I have a concrete floor that I will be self levelling tonight.
I'm putting down underfloor heating with this stuff
http://www.floorheater.co.uk/ - 20mm thick for the walking areas of the kitchen
this leaves me with a ~70cm wide hole around the edge of the kitchen and I want to tile the whole kitchen so I need to find a way to fill the 20mm deep hole all round so I can tile over the top.

I could use 18mm ply glued down to the concrete floor with flexible adhesive? then lay the tiles over the whole lot using flexi adhesive?

Or I could put down cement backer board in 2 layers (12.5 then 6) to get the right height then tile over

or I could put down 12.5mm backerboard on a thick bed of adhesive

what do you think is the best option - or is there another I hadn't thought of?

 

[Richard C]

Not familiar with this kit but had a quick look as you’ve not received any replies & my immediate thoughts are;
1. Surely you are supposed to choose a size of kit that covers the whole floor? Then you would not have the gap around the edge!
2. Can you not get additional blank or even grooved poly panels from the manufacturer?

I would be concerned about using dissimilar materials such as ply or backer boards next to the poly panel heater base board as this will expand & contract at different rates. This differential expansion may well cause the tiles/grout to crack around the edge of the heating mat where the 2 meet. I would not advise using multiple layers of whatever you chose to make up the height either.

Again, not used this particular product before but have tiled over electric mat & wire systems so these are just my thoughts based on tiling experience.

 

[alandyman]

thanks for the reply.
I asked about the extra panels and they advised against them because they would have to come from Sweden and would be an expensive option.

In the end I went for Marmox boards, the reasons being that they are also foam centered so should be similar in expansion to the floorheater boards, they come in 20mm thickness and are stable. Not the cheapest choice but then again I only want to lay this floor once! Has to be said they were very easy to use and lay.

Tiling tonight - ouch my knees ;-(