Laying vinyl over hardened cement based tile adhesive

[tuppence]

I am redoing my kitchen and plan to lay vinyl tiles on the floor. Currently the floor is covered by ceramic tiles but I have been advised to remove them for best results. The present floor is slightly too high anyway so I'm OK with that.

The floor screed was originally laid 18 years ago and crumbled and cracked quite easily before it was covered by the tiles. Maybe it was laid too weak or too dry or maybe it was left uncovered for too long. Either way, it wasn't in brilliant condition when laid.

Now, on carefully taking up the tiles using a SDS hammer drill and tile lifting chisel, I find I am left with a floor in much better condition than I was expecting. The screed is bound together by a 5-8mm bed of hardened cement-based tile adhesive. What I would like to know is if it would be OK to leave this layer in place and use self-levelling compound over it to get a surface ready for the vinyl.

 

[mattysupra]

yes if its well bonded.

 

[tuppence]

Thanks for the advice Matt.

I've taken the tiles off now and the surface is well bonded and reasonably flat so I'll get away with a 3-4mm layer of levelling compound. But there's about 4 sq m of floor space where there were no tiles in the first place and this is about 5-8mm lower than the rest. Is it best to bring this up to a similar level with some sort of undercoat layer first or just level everything in one go anyway? There is no damp problem.

There are also couple of much deeper holes to fill and I need to cut a trench to lay a water pipe in conduit. I assume it's OK to use a weak sharp sand/cement mix to repair these deeper areas.

 

[mattysupra]

a repair mortar is what is needed to fill any small holes and dips etc, and yes, sand/cement for the bigger hole where the pipe is