Own floor plan design city villa 180 sqm with double garage feedback

Hello everyone,

after being active here as a silent reader for quite some time, it was time to register.
A few weeks ago, we applied to our municipality for a building plot and have now received the approval for the land. Although we plan to start building only at the beginning of 2024, we are already thinking extensively about how our house could look. A rough floor plan draft has emerged in the process. I would like to ask you for criticism and suggestions.

Bebauungsplan/Einschränkungen
Plot size: 576 sqm
Slope: no
Floor area ratio: 0.3
Floor space index: 0.6
Building window, building line and boundary: building boundary see development plan
Edge development: see attachment
Number of parking spaces: at least 1.5 parking spaces
Number of storeys: 2 full storeys
Roof shape: SD, WD, ZD, FD
Style direction: -
Orientation: see attachment
Maximum heights/limits: eaves height 7m
Further requirements: -

Building owners’ requirements
Style, roof shape, building type: single-family house with two full storeys and a hipped roof
Basement, storeys: no basement, two full storeys
Number of people, age: 2 adults, 2 children (2 1/2 and newborn)
Space requirement on ground floor, upper floor
Office: Family use or home office? Two offices (GF + UF)
Guest sleepers per year: -
Open or closed architecture: open living / dining area
Conservative or modern construction: modern
Open kitchen, cooking island: open kitchen, cooking island not necessarily required
Number of dining seats: 6-8
Fireplace: no
Music/stereo wall: no
Balcony, roof terrace: no
Garage, carport: double garage with storage space; carport with shed also conceivable
Utility garden, greenhouse: no
Other wishes/special features/daily routine, preferably with reasons why this or that should or should not be: -

House design
Who created the plan:
- Do-it-Yourself
What do you particularly like? Why? Two offices; open living / dining area and cozy sofa corner; children’s rooms facing south; master bedroom facing north; utility room with passage to the garage
What do you not like? Why? Overall, we like our design. We want to have as much of our garden piece facing south as possible. To get even more out of it, the house would have to be narrower and longer (currently 11x10.50). This always failed in our designs because the rooms become too tube-shaped. In addition, as laypeople, we most likely overlook serious planning errors. Therefore, we ask here for constructive criticism and suggestions.
Price estimate according to architect/planner: -
Personal price limit for the house, including equipment: 500k
Preferred heating technology: -

If you have to do without, which details/extensions
- you can do without: garage, the second office / guest room
- you cannot do without: -

Why did the design turn out the way it is now? e.g.
- idea collection from catalogs and Google searches

What is the most important/basic question about the floor plan summarized in 130 characters?
The basic question is whether we have sensibly planned the arrangement of garage, house entrance, and rooms according to the plot and its orientation. Is the design coherent?

The attached picture with the house on the plot (Entwurf.jpg) is a design from the responsible planning office for the development area. We want to build the house and garage aligned exactly as shown. However, the house shifted to the front building boundary and the garage shifted to the rear plot boundary.

PS: We created the design using a rudimentary online tool. Unfortunately, the room names cannot be adjusted in the tool (hence playroom instead of children’s room etc... but I think you know what is meant).

I look forward to your criticism :)!

Welcome to the forum - what immediately catches my attention: Where is the building services room (heating, ventilation, electricity, water, telecom, and co), living room depth 4m, upper floor room depth 3.5m, i.e. the stairs are not aligned, room walls therefore not either, and the stairs seem very short

The staircase also seems too short to me. How long is it drawn?

What floor height should it be, as this is also important for the staircase design.

Thank you for the welcome and your response!

Storage = HTR and has 10.8 sqm. In our opinion, this should be sufficient for technology and a small laundry room.

I actually hadn't considered so far that load-bearing walls have to be aligned vertically. But basically, that makes sense due to the otherwise resulting shear stress. So we need to shift something here. As a result, the bathroom/office on the upper floor will be somewhat smaller – and the children's rooms unnecessarily large. We need to come up with something for this.

Stairs: I overlooked that they are not aligned vertically across the levels. For the length, I followed the tip from the questionnaire with 3.60 m.

Thank you for the welcome and your reply!

Storage = HTR and is 10.8 sqm. In our opinion, that should be sufficient for technology and a small laundry room.

I actually hadn’t considered that load-bearing walls have to be aligned on top of each other. But logically, because of the otherwise resulting shear stress. So we have to shift something here. As a result, the bathroom/office on the upper floor will be a bit smaller – and the children's rooms unnecessarily large. We need to come up with something here.

Stairs: I overlooked that they are not aligned on the levels. For the length, I followed the tip from the question catalog with 3.60 m.

Well, that's nonsense. You usually don't have any load-bearing walls on the upper floor; the roof truss rests on the exterior walls and supports itself. But since the position of your stairs on the upper floor doesn't fit, none of your rooms there fit either.

At 3.6 m and 15 steps, you have a tread of 24 cm. I think that's already borderline.

And you're building around 180 sqm (180 sqm x 2,500 EUR/sqm = 450,000 EUR + additional construction costs + interior furnishings + outdoor facilities). That will be tight with 500,000 EUR, but I'm sure you’ll be told that a few more times here.

I don’t want to go into details and consider what has been shown here more as a sketch of ideas. Kerstin has pinned a decent collection of examples for stairs here (which, of course, must be adapted to your story height), and here I also see a major weak spot: the floor plan only seems to add up conceptually “thanks to” the questionable staircase. Otherwise, for further attempts – please always start anew, don’t patch up the first draft! – as a note for the adjoining room, that the pipes should not be built over (probably here by the garage).

I really hadn’t considered until now that load-bearing walls have to be aligned vertically. But in itself, that is logical because of the otherwise resulting shear load.

At last a questioner himself makes this essential connection, many thanks!

However, I don’t see any load-bearing walls necessary in the dimensions of this building on the upper floor, the reasoning has already been given by my predecessor (although briefly). What is definitely crucial, though, is to keep an eye on the walls of the ground floor due to the downpipes, ceiling openings, and the like. It’s best if you look at the explanations at bauen-jetzt, see "Plan change: from concrete ceiling to wooden ceiling" (from where you are also guided to the priority of the upper floor and to lightweight walls).
Your development plan suggests that a later construction phase is planned behind your garden – who really knows about that?