Insulate concrete ceiling upper floor

What's the situation? Pipe insulation from the hardware store?

Not ventilating the insulation means I have to make sure that the insulation boards are always fully lying on the concrete floor, right? That means for cables or other empty conduits running on the floor, I have to cut out a V-notch at the bottom?

thx

Doesn't matter with what, as long as it insulates a bit. Just take the wool. Throw it in and that's good.
Yes exactly, no gap space. If air flows under the boards, the insulation is useless. So it's not bad at all that you want to put something on top. But unevenness is the death of rigid insulation.

So, I am still in the process of clearing out and cleaning the attic. Almost done - now I wanted to ask again about the procedure with the PUR boards. I just found out that in addition to the 16cm reinforced concrete, there is an unknown insulation layer installed under the floor and then 5 cm of screed on top. Does this change anything about the procedure? The insulation boards are 16cm PUR boards with aluminum foil and tongue and groove edges. I would now simply lay the boards directly on the broom-cleaned attic floor. That means without a vapor barrier and loosely laid.

In another forum I read something that I have to make sure with the PUR boards that they do not lie hollow because otherwise air will flow sideways and significantly reduce the insulation effect... You can prevent this either by gluing them to the floor with construction adhesive (simple tile adhesive, etc.) or by laying a thin layer of mineral wool underneath. What do you think, I would actually like to avoid this effort :-( or is it really recommended? If yes, how many cm should the mineral wool be and do I then have to install a vapor barrier again because of this wool that I lay directly on the screed?

On top, I would lay 15mm OSB boards in the walking area.

No feedback from you? That would be nice..thx

What do you think, I would actually like to avoid this effort :-( or is it really recommended?

No feedback from you? Would be nice..thx

Gladly ;-)
If the floor is smooth, I would save myself the effort. There is also some pressure from the OSB boards on the insulation.