Tiling advice for ensuite (build in progress, with underfloor heating)

[Richhh]

Hi everyone. We're in the process of having a tiny ensuite finished off as part of an extension.

We've not found a tiler yet, but one of the decorators we're using used to be a tiler and says he'll do it for us, but hasn't dealt with underfloor heating before.

The tiles we've chosen are 300mm x 600mm ceramic.

Today the electrician laid the electric underfloor heating mats directly onto the floor that the builders put down (some sort of chipboard/mdf?)...

From what I've read, the tiler just needs to use a lot of flexible tile adhesive (I'm guessing 10mm to cover up the cable clips and thermostat completely!?). Is that right?

It strikes me that if the thermostat cable was channeled into the floor and there were no cable clips, we could get away with using a lot less adhesive?

We're also having the same 300mm x 600mm tiles on the wall. The walls were bare plaster, but have now had a mist coat painted onto them (because the tiles aren't going everywhere, just on the floor and in the shower area).

Would you just tile directly onto the paint/mist coat? Or is there an extra step we need to take before tiling in the shower area?

Thanks a lot everyone.

 

[chappers]

Just lose the clips and tape the thermostat cable down, then you can tile directly over with a decent flexible adhesive such as bal fastflex or tilemaster ultimate or else a layer of flexi SLC over first. Whatever you use check it is suitable to go over electric UFH. to be honest for that format tile I would use a 10mm trowel anyway. make sure the boards are well fixed down too.
Personally I would have backerboarded the shower area, wouldn't recommend tiling over plaster and paint, but you have what you have now and I'm sure you're not going to change it, so use a decent powdered adhesive and prime with SBR first, the floor should really have been primed first too.