Prepping floor for new tiles - kitchen/conservatory

Hi all, I have a tiled floor in the kitchen/conservatory and quite a few are starting to come loose. They weren't very level to begin with so I thin the previous owner did a bit of a bodge job!

I have got an SDS tile remover bit and have removed a small section to see how it would go, it is working great but is damaging the screed below and exposing insulation in some area's (and the underfloor heating cables, but if I have to redo this thats not the end of the world).

Seeing as theres some big chunks coming loose in places, what is the best way to prep the floor for new tiles once I have all the old up? I was wondering if self levelling compound would sort this out? I have atached a picture of the state of my test section!

Thanks

 

The UFH will not be salvageable. Make sure it's disconnected before proceeding further (not just switched off).

If the blue stuff in the picture is the floor insulation, something is very wrong.
Screed over insulation should be 50mm or more in thickness.

 

Hi, the blue stuff is definitely insulation, if I do not cut the heating wires why would the UFH not be salvageable? I have managed to not damage them so far in the small section I have done.

What would you recommend to do if the screed is not thick enough as it seems it isnt?

Many thanks for any help!

 

The blue stuff could be Marmox/wedi style tile backer boards - a blue styrofoam sheet coated both sides with a cement layer with reinforcing mesh. Commonly used to separate e.g. A concrete slab from electric underfloor so the UFH actually stands a chance of warming up

The marmox boards need to be glued down well to the slab underneath as they're flexible and will allow tiles to move. Over time, foot traffic would work tiles loose if the marmox were flexing

If you're planning on re doing this entire layup then carry on with the sds drill, but the fastest way to get it up will probably be to smash the a few tiles and the marmox underneath it, then just use a spade to separate the marmox from the slab underneath and rip the tiles up with it

If your plan is to lift the tiles and not smash the UFH/ marmox boards you've got a bit of a battle on. Marmox boards (10mm version) can be had for about a tenner a square metre, thicker cost more..