Which flooring is suitable for underfloor heating?

With paint, you can certainly see every scratch and you can't easily repair it either.

how many hours did he need for that?

I just checked the construction calendar again. The floor layer was in the house for a total of 12 days. However, the work with him was coordinated in such a way that we could always already furnish the finished rooms. This was possible because the move from the old to the new house was only a distance of less than 100 meters.
If the question refers to what the work ultimately cost, I point out that the quoted amounts relate to the material including the gluing. That is why the skilled worker hours are set to € 00.00.

That is very cheap, you definitely can’t get that anymore today. The prices today are only for the material. For the work, you then have to add the same amount again (if not more).

To save money, laminate is definitely the money-saving tip. I bought laminate from Kaindl with office hardness class at Obi during a 15% sale Sunday. In the end, for 10 EUR/m².

Then there is also the impact sound insulation and possibly a vapor barrier.

Laminate just has a different feel and the sound is different too. But for the price it’s a solid deal.

what is also important to me is that the volume when walking on the floor is relatively low and remains within limits and is not extremely loud.

With our current cheap laminate, the volume is very loud, especially when the dog walks over it with its claws.

we only need impact sound insulation for all floors, right?

vapor barrier is not necessary with underfloor heating or is it probably even counterproductive, right?

so the lacquered prefinished parquet is not so good?

Sorry, unfortunately I have no idea :/

what is also important to me is that the volume when walking on the floor is relatively low and remains within limits and is not extremely loud.

Here, glued vinyl is also recommended. I would really go to the floor installer / upholsterer I trust and ask about the current prices ...

However, parquet is not always expensive. For the children's rooms, we chose a store brand from the hardware store for 22 euros/sqm. Store brand from the hardware store, but without harmful substances, [blauer Engel], that was important to us. It doesn't always have to cost more, but still durable and no plastic.