Our floor plan design for an affordable house

Development according to § 34 Baugesetzbuch)

Country house character

Note that when building a house under § 34, you have to build like the neighbors.

Design (this indeed comes from us after reviewing many floor plans...I know it is not very well received, but we simply have a pronounced DIY mentality and I love designing myself anyway)

I think it's good, I'm like that too. However, note that walls drawn by you often end up with different measurements. So plan with 15 instead of 10 cm, since plaster also reduces some surface area.
Keep in mind that you might inadvertently introduce mistakes.

[*]inexpensive building materials like Ytong, the roof covering is planned with aluminum sheet
[*]simple floor plan with load-bearing walls in the middle for short spans, bathrooms/pipes stacked

I once read such a book too. However, our site manager told me it costs almost nothing if one bathroom is not directly above the other. So if you have a disadvantage in planning because of that, you lack basic knowledge and rely on ignorance.

Yes, there is a lot of unused space. I also don't know exactly what to do with it or how to use it more sensibly. I

You definitely lack storage space.
I would first add railings to the floor-to-ceiling windows on the upper floor. Advantage: more protection and coziness in the bedrooms and space for placing things.
In the bedroom, I would either build a very deep wardrobe with a lot of storage space myself or move the wardrobe further forward and have storage space behind it, or ideally set up the sewing corner there in the bedroom.
For this, a storage room instead of a sewing corner in the hallway. Advantage: you can work undisturbed and the children have their peace.

Ground floor: definitely keep a cabinet wall of at least 60!!! cm opposite the stairs. Anything else would be pointless. Create a storage room under the stairs. Consider a spiral staircase.
Close off the work area towards the hallway with a wall. Possibly separate it from the living area with a sliding door, so you can also leave the vacuum cleaner and clutter/papers visible there sometimes.

Exterior view: use proper single-pane windows. I don't know what windows you took there, but they should be about one meter wide and 138 cm high. Or have a railing of about 88 cm. This goes more in the direction of normal cheap construction and also looks different than these 80 x 80 (or whatever that is supposed to be).
Country house character (if possible under § 34) also works if the plaster is painted.
Regarding the windows, I would mediate if the others have the right size. Visually, it doesn't work as it is now.

p.s. Definitely rotate the stairs. Then you can still gain a storage room next to the bedroom upstairs.

The draft is not approved by an architect, but by our planner (civil engineer with over 30 years of professional experience), who will also submit the building application

I consider this a mistake. Reason see above.

I also read a book like that before. However, our site manager told me that it costs almost nothing if a bathroom is not located directly above another. So, if you have a disadvantage in planning because of that, you lack basic knowledge and rely on ignorance.

Now don't ruin everything we try to instill in people here. Of course it costs something, namely a considerable amount of living comfort, if a downpipe is built between the dining table and the sofa.

The design is approved not by an architect, but by our planner (civil engineer with over 30 years of professional experience), who will also submit the building application.

The gap between draftsman and architect can also be bridged with a forum community. At least here - in the green forum, I would see it differently.

where the ground floor is supposed to be 2.84 m high and the upper floor 2.60 m high.

Then the staircase won't work, I think. And if the staircase doesn't work, everything is useless. So better check -> google "Treppe 1x1".

The design is calculated by a planner from my father-in-law’s circle of acquaintances, who is giving us a pretty good price. He handles all the statics and does application and execution planning including energy efficiency stuff.

Especially with building a §34 house, it makes sense to hire an architect who is familiar with the practices of the building authority. §34 is not a free pass!

The design is not approved by an architect, but by our planner (civil engineer with over 30 years of professional experience), who will also submit the building application.

He may be a good civil engineer, but he simply has no experience as an architect.

but we trust ourselves with that. The current floor plan is not particularly extraordinary anyway.

No, it isn’t. But it still looks amateurish at the moment. (Lack of storage, lack of privacy... take it as you will.)
I am currently redrawing the floor plan and have to find that the exterior walls somehow have nothing to do with 36.5 plus exterior plaster.
Anyway. I took the outside dimensions 8.20 x 12.80 and more or less transferred everything.
I would rather do it like this:
equivalent children’s rooms, one bedroom with enough closet space, the office on the upper floor as a craft/sewing room, some space for storage in the hallway, on the ground floor a closed office/storage room, a generous wardrobe space in the hallway, a standard kitchen. It reminds me somewhat of the thread by ... ( , you probably know which thread I mean... the one with the flaw at the west side and too small all-purpose room, but with a fireplace)
The windows roughly align well with their counterparts on the lower floor...
Unfortunately, the program does not provide dimensions. The children’s rooms are 13.4 sqm, and anyone who knows me knows that I make space for closets
Overall an interesting project, where I hope the EL (energy labels) are positioned well enough that you can also build and finance the house.

Now don't go breaking everything we otherwise drill into people's heads here. Of course it costs something, namely a significant amount of living enjoyment, if a downpipe is dry-installed between the dining table and the sofa.

In my little booklet (not a book), even the pipes and heating pipes were on concrete walls. Unplastered, of course :P