Screed execution in the attic - ceiling between the attic and living space

Hello,

I am currently building a KFW 55 house, have an insulated roof and beneath it is an attic (concrete ceiling), below that is living space.
I would like to plan a screed here.
Now to my question: is the screed between the attic and the living space sufficient as insulation or should I add insulation?
How much heat will I lose here?

Regards

Now to my question: is the screed between the attic and the living space sufficient as insulation?

The screed does not insulate at all. Otherwise, it would be called insulation and not screed ;) .

Question: Why insulate the upper floor ceiling if you have an insulated roof? What do you intend to do with the attic? Why screed?

The screed does not insulate at all. Otherwise, it would be called insulation and not screed ;) .

Question: Why insulate the upper floor ceiling if you have an insulated roof? What do you intend to do with the attic? Why screed?

The attic is intended to be used as a storage area.
I initially wanted to leave the attic without screed.
However, there are too many pipes and cables lying around.
The question is basically how much heat do I lose through the attic or can I neglect it?

The question is what amount of heat do I lose here through the storage, or can I neglect it?

If the roof is the thermal envelope, then you always lose the same amount there, regardless of whether there is screed or not.

I wanted to leave the attic floor without screed at first. However, there are too many pipes and cables lying around.

Ok, you have to decide that for yourself.

The question is what heat do I lose through the attic here or can I neglect it?

Nothing, it all stays inside the house and is not "lost" since the roof is insulated.

Ok, you have to decide that for yourself.

Nothing, it all stays in the house and is not "lost" since the roof is insulated.

Is it then sensible to insulate under the screed? What about the cost-benefit ratio?