Screed protective screed attic on concrete slab

Good day everyone,

I have now insulated my attic (Dampfbremse and 2 x 10 cm Styrofoam).
According to my construction company, a protective screed is to be laid on top.
Does anyone here have experience with what such a thing may cost?

The area is almost exactly 100 sqm.

Thank you very much.

Protective screed refers to a function, not a specific material. So what is supposed to be installed?