6mm insulation boards on concrete under slate floor

[contactkay]

Hi just hoping someone far more knowledgeable will have the answer. I've got a concrete floor which is a bit crumbly in places. I plan to stick down 6mm polystyrene insulation boards then underfloor heating and slate tiles. Is this sensible or will I ruin the tiles?

 

[White Room]

I would sort the crumbly screed floor out first.....

 

[Andy Tiler]

Hi just hoping someone far more knowledgeable will have the answer. I've got a concrete floor which is a bit crumbly in places. I plan to stick down 6mm polystyrene insulation boards then underfloor heating and slate tiles. Is this sensible or will I ruin the tiles?

I wouldn't lay anything on a crumbly floor!! Any pics?

 

[contactkay]

Here's a rough photo, was slightly worried someone might mention to sort the crumbly floor out first. Would the insulation boards not sort that out?

- - - Updated - - -

And the pipework is all gone

 

[White Room]

Is some of the areas on the screed hollow or is some of it flaking on the surface....

 

[Andy Tiler]

Here's a rough photo, was slightly worried someone might mention to sort the crumbly floor out first. Would the insulation boards not sort that out?

- - - Updated - - -

And the pipework is all gone

Nope!it's all about the prep, it's only as good as the floor your sticking to!!

 

[contactkay]

Hmmm. There's mainly hollow bits in the screed. Nothing flaky. The vast majority is sound. Just a few bits around edges and doorways.

 

[White Room]

Remove and fill the hollows areas......

 

[contactkay]

Ok thanks everyone. Such a pain because I really needed this floor done by Wednesday:mad2:

 

[bugs183]

Also is the insulation board the flimsy (often pink) type with no cement bonded to it?? These are very brittle and can compress under time.
If so i'd consider swapping these for a more substantial type of board like Marmox.

 

[White Room]

Ok thanks everyone. Such a pain because I really needed this floor done by Wednesday:mad2:

Use a deep fill self leveling for the repairs, sets in a few hours.

 

[contactkay]

Thanks for that guys!