Is it possible to lower the floor structure?

You want to remove a screed including underfloor heating to subsequently insert 1 cm more insulation (and improved impact sound insulation so that less noise from the ground floor is heard in the basement)? Just before Christmas is a bit late for April Fools' jokes.

My building planner originally only planned with standard height hollow brick.

The number of stacked bricks, however, is flexible. You must have expressed your wish, or did your planner have to comply with the heights of the development plan?

Changing the floor structure now is a real Pyrrhic victory for me. What exactly room height are we talking about? I would work with color and try to make the rooms appear higher visually. Even if you bring a professional on board for that, it will be cheaper than turning your house into a construction site for months.

The number of stacked bricks is flexible, however. You must have expressed your wish or did your planner have to comply with the heights of the development plan?

I found the introduction

My planner back then only planned with standard height hollow bricks, and that is still my biggest problem and annoys me greatly.

misleading especially because I initially thought of NF bricks on a wooden beam ceiling and then wondered why I didn’t see this repeated in the floor structure.

For now, I am only concerned with whether it is possible and, if so, how many centimeters would be reasonably feasible and what needs to be considered. Whether I actually do it is another question. Does [Fließestrich] also need to be heated, and does it also cause high humidity?

My main concern is whether it is possible at all and if so, how many centimeters would be sensibly possible and what needs to be considered. Whether I actually do it is another question. Does flowing screed also need to be heated and does it also generate high humidity?

Yep, it does. Yes, a lot of water has to be evaporated.

Does flowing screed also need to be heated, and does high humidity also arise there?

Yep. That turns your place into a sauna.

Unless you use poured asphalt screed. It’s much thinner, without moisture, and can be covered immediately.