D
Dumbo
I would take them up . Skim over with levelling comp stick down boards . Lay ufh level over then tile .
As @Localtiler says you are looking at a extra height build up of 25 to 30 mm on top of your existing tiles so probably 40 mm off of the screed.
As @Localtiler says you are looking at a extra height build up of 25 to 30 mm on top of your existing tiles so probably 40 mm off of the screed.