Cost estimate for construction costs of a semi-detached house including ancillary costs

Hello everyone,
We have an interesting building plot in mind with the following key data:

[*]Greater Munich area
[*]Plot 252 sqm (9m x 28m)
[*]Max. footprint: House 6m x 11m + Garage 3m x 8m
[*]Floor area ratio 0.8
[*]Site coverage ratio 0.6
[*]Two full floors
[*]Gable roof 35°
[*]Eaves height 6.50m
[*]Developed (district heating available) and ready to build immediately
[*]Currently flat green meadow in an existing residential area

To ensure our wishes as well as the financing, we are very interested in tips here in the forum or recommendations for contact persons.
Our wish

[*]Solid house
[*]Approx. 135-145 sqm living space
[*]Basement, ground floor, upper floor, converted attic + single garage
[*]Bathrooms: ground floor, guest toilet, upper floor bathroom with tub, attic shower bath
[*]Equipment level: medium
[*]No personal contribution
[*]One contact person for the construction project “turnkey”
[*]Implementation/ start in the third quarter of 2024

Open:

[*]Heating: heat pump vs. district heating?
[*]Photovoltaic system (+ storage)?
[*]Gable window in the attic facing the garden

Since the development and schedule of the neighboring plot are not yet determined, we assume that the two semi-detached houses will be built separately.

Our questions:

[*]Rough cost estimate for the construction project including additional costs (development, garden etc.)
[*]Recommendation for contact persons, possibly architects, to discuss the project in more detail

Rough cost estimate for construction project including additional costs (development, garden, etc.)

Calculated with a bit of buffer approximately €600k all in without basement.

I know Munich is not a market for average earners. Despite good job offers, we quickly decided against living in Munich after graduation, so as not to risk dreaming of buying a house for the family there. I would never put up with a 6 m wide house given the land and construction prices in Munich. That leaves only about 5.5 m net width inside. And if a staircase has to connect four floors, it gets scary. Especially with children. The subdivision of the plot basically says everything you need to know.

Your project raises so many questions.
Is the neighbor also building with a basement? If not, you have to plan and finance the excavation support.
How much do the two halves need to be aligned? How do the gables relate to each other? Does the garage have to be located at the position? With such dimensions, a side entrance is often more practical than entering the house from the front. Otherwise, you would always have to go through the garage.
Is the gable roof pitch longitudinal or transverse? A 35° pitch over 11 m length is extremely steep; with a width of 6 m, there is not much height left in the attic for a staircase, a shower bathroom, and a room to be used as a bedroom or children's room.
How many children will live there?
I have real problems imagining how you want to accommodate the room program. You lose 1 m of the 5.5 m width on each floor for the stairs and then have to allocate a landing and a small corridor. On the ground floor, you could still try an open-plan concept, but on the 1st floor, you at best get two 4 x 4 m rooms, one of which is supposed to be the bathroom. I know such narrow houses as terraced houses from the last century, and the living quality is rather limited unless you live strictly minimalist. You run yourself ragged because the basement is often the only storage area.

My cousin also has a similarly sized semi-detached house in Cologne (6.0m x 11.50m). Of course, everything is tight and quite narrow, the stairs are relatively steep. The house is located in a new development area with about 100 more or less identical semi-detached houses. So it seems to be possible to live in such a house. They have in the basement: 3 cellar rooms on the ground floor: kitchen, living/dining room, WC, hallway on the first floor: bedroom, bathroom, children's room in the attic: study, children's room, WC

The question is whether you want to put so much money into a house like that. The planning can only be done sensibly with an architect and will quickly be >3000 €/sqm in the Munich surroundings. Then there are the costs for the building plot, which will surely also be >2500 €/sqm. That way, you easily crack the million for a house that is hardly more than a little house.