levelling a ceramic tile floor

[xeb]

i have an existing very uneven ceramic tile floor layed over top of two different kinds of stone tiles. i went and got some levelling compound today then had someone tell me you can't put it over ceramic tiles. taking up the ceramic tiles is prob not too much of an issue but taking up the stone ones will be and will add a large cost as i'll then probably need ~15mm of levelling compound.

any thoughts on whether it's a sensible option to lay compound over stone tiles (they're pretty polished) and what sort of primer i should use?

i'm using water based levelling compound

thanks in advance!

 

[JerryM]

i am not sure on this one but add what i know.

if i am not sure about a surface i will try a small amount of the levelling compound first and see how it goes (leave it 24 hrs and see how easy it is to get off).

i would take the ceramic tiles up. an alternative would be to score them with an angle grinder but probably more effort than it's worth and very dusty. having taken the tile up i would then use sand/cement screed to take level back up to allow 5mm for leveller (nb self levellers only level to 3mm and need towelling out initially).

i think it would be ok to lay compound over stone tiles. i would test a small area 1st. if it needed a primer i would use neoprene.

it is important that the sub floor ie stone tiles are firm ie not sinking/moving as this would lead to cracking of the self leveller once installed.