Floor tiles.

[baldkev]

Xps is expanded polystyrene, and id question how much compression and thetefore movement you'd get? I can see its only 6mm thick, but it only needs half a mm to a mm of deflection to cause a cracked tile?

 

[Phil Pascoe]

I'll use 10mm, but I would think it to be OK as it's specifically made to go under tiles.

 

[Phil Pascoe]

Right, 10mm board and some underfloor electric heating. The mat I'm looking at is 3.5mm thick, so I'll need to pack the unheated areas to make the 3.5mm up. I would imagine there's a product specifically for this, but I can't seem to find anything. I know there are ways and means but there must be an easy way?

 

[paulrbarnard]

Right, 10mm board and some underfloor electric heating. The mat I'm looking at is 3.5mm thick, so I'll need to pack the unheated areas to make the 3.5mm up. I would imagine there's a product specifically for this, but I can't seem to find anything. I know there are ways and means but there must be an easy way?

I made this mistake in our wet room. I laid the heating elements but didn’t cover the whole floor (needed to avoid where things like the shower screen fitted to the floor). I figured I would just trowel in the adhesive thicker. It worked pretty well with the exception of one tile, which VERY annoyingly is on the edge of the sloping shower tray, that sagged slightly resulting in it leaning the wrong way. It’s not enough to cause water to flood out but annoys the heck out of me every time I look at it.

Definitely look at something to level up between the heating elements.

 

[akirk]

You can buy that material with grooves cut out for wet underfloor heating - we have just had it put into our conservatory - tilers come tomorrow - but they used lasers and a screed to get the floor perfectly level first and then all spare gaps are being filled in with a screws - air pockets cause tiles to crack…

 

[scholar]

This is an alternative option

https://www.marmox.co.uk/applications/marmox-underfloor-heating
I have used Marmox board on a few sundry jobs - it seems very good to me. I don’t know how it’s compressive strength compares, but properly installed (solid bed) and with properly installed (solid bedded) tiling, I don’t think you would have a problem.

Cheers

 

[Phil Pascoe]

There are many similar with much the same specs. I can't see a problem because they are specifically designed to use under tiles.