Levelling a DPM floor? - Tile Advice

[Steven]

Good morning tilers,

A neighbour has recently asked me to look at tiling the floor in his garden room. The screed is incredibly rough and will need levelling first - the problem is he has already gone over it with a DPM (liquid I think). This is a new problem for me and I'm not sure how/if that can be tackled. Am I right in understanding that a self leveller won't bond leaving it to just crack? Any help would be really appreciated - how and if I can carry out the job successfully.

I have attached a couple of pictures.

Many thanks.

 

[demi34]

Ball level max can be used

 

[Ajax123]

Sand it then over prime using an epoxy primer, sand blind whilst tacky allow to set vac up any loose sand then use whichever cement based levelling compound you like.

 

[Steven]

Thank you guys for responding - really useful info. I'll look to go down those paths.