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 underneath 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 living space sufficient as insulation, or should I add insulation? How much heat do I lose here? Regards

Is that a wooden beam ceiling to the attic? Probably yes. Do you want to do it yourself or have you asked your general contractor if the ceiling also supports the screed structurally?

Is that a wooden beam ceiling to the attic? Probably yes. Do you want to do it yourself or have you asked your general contractor if the ceiling also supports the screed structurally?

I have a concrete ceiling, I believe 20cm thick.

I wouldn't have any real worries with a concrete ceiling. The screed only weighs about 100kg per sqm. A party with many people can potentially have greater weights, which are also not evenly distributed.