Floor levelling compound on top of vapour barrier?

[thepowells]

Hi

We are refitting our kitchen and are planning to tile the floor, which is currently a concrete base topped with polystyrene slabs (presumably for insulation) which is then covered with a plastic sheet for the moisture barrier. On top of this is chipboard (floating, locked-together sheets) which has over the years got wet and is now crumbling and has sunk in places.

We are going to replace the chipboard and top it with waterproof plywood in order to support the tiles, however we need to level out the dips in the floor first (where the polystyrene has been crushed slightly). In order to avoid taking up the moisture barrier plastic sheet, is it possibly to pour a latex levelling compound on top, then lay the chipboard, or will this cause a problem?

Dont know if the latex will damage anything...

Thanks in advance!

 

[^woody^]

Turn the polystyrene around

 

[thepowells]

a very good idea, although we were hoping to avoid having to lift the vapour barrier, but might be easier than the other alternatives. thanks for the very obvious answer!