Screed or tiles with a concrete look

what do you mean by clearly more than a renovation? Is that already a refurbishment?

I have not yet had the pleasure of refurbishing buildings. Therefore, I do not know exactly where the obligation for approval begins – but I do know the mistaken popular belief that anything that remains within the existing shell is none of the authorities' business.

the terrazzo is the one with the stones inside that looks speckled like that?!

(The) terrazzo is exactly that. How speckled it looks is, of course, variable. It can also look as if marble has been "poured." Or speckled so subtly that it appears much calmer. Or spread so thinly like the craftsmen who can still do it today.

THE terrazzo ( soll mir recht sein ) then I'll see what I can find there on the internet.... Thanks for the hint

Regarding approval, no craftsman or architect has mentioned anything in that direction so far... but basically everything stays where it is now

Approval is absolutely not necessary either. It only becomes interesting if under certain circumstances it changes the living area, etc. On the topic: have you perhaps looked into asphalt screed?

On the topic: have you perhaps inquired about asphalt screed?

No, I haven't heard of that yet, resin, cement, etc. all tried already. but mastic asphalt! It sounds interesting on the internet, especially since it would exactly meet our requirements.... underfloor heating/ wet area thanks, that's a great tip

...Cast asphalt is only possible as long as the windows or glazing are not yet installed!