Preliminary floor plan for single-family house

Hello friends,
as the thread name already suggests, we plan to start building the house in 2016 and will begin planning together with the architect in mid/end of January.
Plot already purchased.

Development plan/restrictions: no development plan
- Size of the plot: 30m * 32m / 960sqm, access possible from south or west as it is a corner plot, on the east side a 10m wide compensation strip with meadow behind it. On the north side the next plot
- Slope: No slope
- Floor area ratio: 0.3
- Number of floors: 2 full floors, no basement
- Roof type: "modern" gable roof (17°-20° pitch *desired*)
- Style: modern, white house, anthracite-colored windows with venetian blinds on the ground floor.
- Orientation: ridge W/E
- Further requirements: Cistern at least 3000L as a condition because of rainwater
- Number of people: Currently 2 persons (29/27); children planned: 1-2
- Space requirements on ground and upper floor: spacious living-dining area on the ground floor with "separable" kitchen.
- Office: office/fitness/guest room
- Overnight guests per year: currently 4, possibly more in the future
- Open architecture: high ground floor with ceiling height 2.65-2.75m.
- Open kitchen, cooking island: kitchen island desired
- Number of dining seats: 8 persons, large dining table
- Fireplace: as a "room divider" between dining and living area
- Music/stereo wall: "home cinema capable living room," tension motorized screen (3.4m wide) + projector, 7.1 Dolby Surround (to be later converted to Dolby Atmos with ceiling speakers).
- Balcony, roof terrace: no balconies, but terrace on the south side,
- Garage, carport: double garage with storage space

House design
Who is responsible for the planning:
- Architect: only from January
- Do-it-yourself with SH3D
What is disliked: long corridors, I don’t know how long the stairs have to be with a ceiling height of 2.65/2.75m, for now I assumed a worst case length of 4.6m.
Price estimate according to architect/planner: none yet. My estimate: with own work (bathroom/tiles/flooring/paving/painting) 310,000€
Personal price limit for the house including equipment: 350,000€
Preferred heating technology: gas boiler with solar

If you had to give up, on which details/expansions
- could you do without: upper floor can be smaller, children’s room with 17sqm would be enough. I only don’t know which is cheaper: 1) bay window on the ground floor to expand the large living-dining area or 2) as in the current sketch.
Double garage could also become a "normal" garage with carport.
- could you not do without: large living room with at least 4.2m wide wall opposite the couch. I wanted to put the heating system between the house and garage on the west side.

I would appreciate your criticism.
Thank you very much! Greetings from Bavaria

House planning is not my thing Costs I prefer to look at, and I have to point out one thing to you: build smaller or screw your budget up significantly

Thanks for the tip, I think you're right. Both the house size and the budget are not set in stone. A friend of mine built a 13*10m (181sqm) house with a double garage nearby for 310,000€ turnkey. Since he had a hip roof, I was hoping that with a gable roof and similar equipment I would come to the same range. So far I have estimated the following (really just estimated, my eyes will only be opened in January ): Shell construction: 90,000 Roof: 20,000 House installations: 6,000 Stove: 9,500 Heating: 15,000 Sanitary ground floor: 3,000 Sanitary upper floor: 7,000 Electrical: 15,000 Doors: 7,000 Sliding door kitchen: 3,500 Windows: 21,000 Shutters/blinds: 13,000 Front door: 3,000 Garage door: 3,000 Floors: 6,500 Painter: 3,500 Paving: 7,000 Kitchen: 13,000 Interior/exterior plaster: 28,000

However, I read over 230 sqm of living space with you. - to be built in the expensive South. Simple equipment 230 sqm x €1,500 = €345k + garage + garden + room divider fireplace + incidental construction costs ==> with that size, there will be a solid 4 at the front, with a few special requests and furniture (I already see home theater, high ceilings - surely more will be added) you can also reach the 5... Is a KfW level interesting for you? Then you also have to think about the building technology.

You are right, the size came about because I myself have too little knowledge of planning. I wanted to use the design to show the basic room layout, that the "thing" is too big, that's what every reasonable person tells me so far. The home cinema is already in place, I just have to "move" it. The only addition will be the ceiling speakers. KfW, I must admit, I haven't really dealt with it yet. So far, I was/am under the impression that it is not worthwhile to take out "more money" for a "cheap" loan. The architect we have is also calculating with 1500€/m2... He just has to, so to speak, "shrink" the house now.

Then I recommend you wait until January and then visit the forum again.
By the way, your list is missing garden/terrace including earthworks, garage, drywall construction, all incidental construction costs + architect's services (for a project of this size, the architect's fee can quickly amount to around €20,000), cistern.
Also, for example, the floors at €6,500 are very inexpensive; that is not €40 per sqm including adhesive, baseboards, silicone/acrylic.