Square single-family house 9m x 9m on corner plot

How are the "2H" to be understood? Maximum 2 full floors?

I would view the roof structure somewhat critically:

[*](Where) are the load-bearing purlins supported according to the sectional drawing?
[*]Why this type of "mansard hip roof" and not a pyramid roof?
Then all the ridge rafters would meet at a point and you get stable triangles.
[*]The dormers further weaken the overall rigidity (and by the way are missing in the plan view).
[*]For the knee wall, horizontally acting forces could be tricky, e.g. if the structure is designed as a rafter/common beam roof.
I would rather set the roof structure directly on the (reinforced concrete?) ceiling and if necessary make the roof pitch a bit steeper – depending on whether it has to fit, for example, into an older, established environment with >= 50° roof pitch or would do so.

Do you mean that the T-solution doesn't work well? I would like a T-bathroom. We will probably also move the wall to the master bedroom (which will more likely become a children's room...) 30 cm further to the southwest, then the bathroom will be somewhat larger.

Well, it would have been a bit tight with the cabinet behind. But if you give another 30 cm, it looks better. How wide are the passages to the shower and toilet? I wouldn't recommend anything under 65.

Well, with the cupboard behind you, it would have been a bit tight. But if you give another 30 cm, it looks better. How wide are the passages to the shower and toilet? I wouldn’t recommend anything under 65.

They are currently planned with exactly 65 cm, the shower has a width of 1 m, the toilet 1.30 m.

How should the "2H" be understood? Maximum 2 full stories?

I am somewhat critical of the roof structure:

[*]Where are the load-bearing purlins placed according to the section drawing?
[*]Why this type of "mansard hip roof" and not a hip roof?
Then all the hip rafters would meet at a peak and you would get stable triangles.
[*]The dormers further weaken the overall rigidity (and by the way are missing in the top view).
[*]For the knee wall, horizontally acting forces could be tricky, e.g. if the structure is designed as a rafter/collar beam roof.
I would prefer to set the roof structure directly on the (reinforced concrete?) ceiling and, if necessary, make the roof pitch a bit steeper – depending on whether, for example, it has to fit into an older, developed environment with a roof pitch of >= 50° or would have to.

Hello nunc carcer, that is a very interesting remark. You seem to be a professional; I am not at all. But I can give you an answer as to why: We are not building in a new development area, but in a developed one, where indeed many of these "mansard hip roofs" can be seen, mostly with a significantly steeper roof pitch. This idea was therefore adopted here, among other reasons because the house will be located at a prominent spot at the intersection. In the case of a hip roof, the attic would be significantly less attractive – or we would become too tall.

Regarding the limitations: 2H means that the wall height must not exceed twice the setback distance to the neighboring property; in this case, we are limited to a wall height of 7 m. The total height of the house is limited within the quarter (= a "block" surrounded by streets), but here we might still have some leeway.

We will be speaking with the structural engineer soon; of course, we want a stable house. What questions could we ask in addition to the ones you mentioned above?

Personally, I always find it a pity that such value is attributed to the TV set.

The couch faces inward and the TV is mounted on the interior wall. This way, you look from the couch into your house and not onto your property. Furthermore, the window will always be closed, because otherwise the sun shines directly on the device.

Are you sure it is 2H? That would be wall height x2. More like 1/2H? Which federal state is it? Do you have a floor plan where the clearance area is marked? Definitely pay close attention to that, our architect cost us half a year here due to faulty calculations. Therefore, I would always question this. Also important: do you have a dimensioned section through the staircase in the attic? I can hardly imagine that in the attic with a 45-degree roof pitch there is enough headroom left to comfortably use the stairs – even if it looks like that in the unmeasured section. Otherwise, I think the roof shape is great! Why not generate a bit more space in the attic by having a slightly steeper roof pitch? Aesthetic reasons? I would plan the kitchen once, with the placeholder it looks like there is somewhat too little sensibly usable space because of the many corners. The terrace with 2.5 m is relatively narrow to comfortably place a garden table with chairs. If the attic might eventually be used as a parents’ area, think carefully about where the bed should be placed – a 2 m bed + enough space on the right and left to comfortably get in and out without hitting your head. With this roof shape, the roof load must be supported at the "kink," ideally close to the corners via supports – but that’s what the structural engineer will handle.