Insulate concrete ceiling upper floor

Can you simply lay the EPS loosely on a concrete floor without laying a screed over it? What if the top floor slab consists of concrete and a 3 cm screed? Is it allowed to lay the EPS on the screed as well

Simply on top

What I would do or will actually do soon is glass wool batt insulation. Costs for 36 cm thickness (double layer) with WLG 35 only 10€ per sqm (but I have it done by a company, I have a cold roof - no walkable attic needed).

Otherwise, I would take the 160 mm PIR boards from the offer for 15€ per sqm (WLG 23?).

For your orientation so that guessing is easier, the energy saving ordinance currently stands at 0.24 W/(m²·K) ....

Which material may be used for what is stated in the approval.

For your orientation so that guessing is easier, the Energy Saving Ordinance currently stands at 0.24 W/(m²·K) ....

Are you threatening the OP with the Energy Saving Ordinance police? By the way, with both proposals, the ceiling then has a value of 0.10-0.15.

I only prevent stupidity to answer your question in your words

Just do it What I would do or will actually do soon is glass wool batt insulation. Costs for 36cm thickness (double layered) with WLG 35 only €10 per sqm (but I have it done by a company, I have a cold roof – walkable attic is not necessary). Otherwise, I would take the 160mm PIR boards from the offer for €15 per sqm (WLG 23?).

You mean the PUR rigid foam boards both sides aluminum laminated, WLG 023, 160mm,? Then double layered, so 320mm insulation? Would I then have to lay OSB or chipboard panels on the rigid foam boards if I want to walk on it and store boxes? I had also considered glass wool, but I still want to be able to walk in the storage and use it as a storage room. What about exposed glass wool and the fine dust development? Does any of the glass wool get into the lungs (seriously)? Otherwise, I could of course insulate the non-walkable part with glass wool. So you used 180mm glass wool double layered? The advantage with glass wool would certainly also be that the cables etc. underneath do not create thermal bridges, right? Best regards

You mean the PUR rigid foam boards laminated with aluminum on both sides, WLG 023, 160mm,?
Then apply them double-layered, so 320mm insulation?

Yes, exactly.
But please only single-layer! That already gives you insulation values suitable for good new buildings (see my U-value specifications). I would then put boards (OSB or similar) on top of that.

I had also considered glass wool, but I still want to be able to walk in the attic and use it as storage space.

Then glass wool is out.

So you used 180mm glass wool double-layered?

I at least commissioned a craftsman to do so during my house renovation. But it is an attic that will never be walked into again (or only if, for example, the multiswitch of the satellite system located there is defective).

The advantage of glass wool would certainly also be that the cables lying underneath do not create thermal bridges, right?

Mill a small channel into the PUR where the cables lie. That way, there are no thermal bridges either. Everything is better than uninsulated.