ᐅ Floor Plan Design for a Single-Family House on a Large Sloped Property

Hello dear forum,

we look forward to your input on our planning. The plot is fixed, but the design, construction method (solid/wood frame), and approach (general contractor, owner-builder) are still completely open.
Below you will find our questionnaire; I hope it is complete and not answered too extensively.

Development plan / restrictions
Plot size: 1000 m² (10,764 sq ft) buildable area, total 3600 m² (38,750 sq ft) including forest and meadow areas
Slope: There is a slope, rising approximately one story height from the street (north) towards the garden (south)
Floor space index / plot ratio: unplanned inner area, depends on surrounding development
Floor area ratio: unplanned inner area, depends on surrounding development
Building alignment, building line, and boundary: Building allowed up to the southern edge of the current existing structure
Edge development: see pictures
Number of parking spaces: two garage spaces for us, two garage spaces for the neighboring father-in-law to be built on our land, so a total of two double garages
Number of stories: Surrounding buildings have 1.5 stories with pitched roofs
Roof type: gable roofs or half-hipped roof (Dutch gable)
Architectural style: none specified
Orientation: north-south
Maximum heights/limits: height of neighboring buildings unknown
Other requirements

Owners’ requirements
Architectural style, roof type, building type:
We like the Mediterranean style and would probably decide on a half-hipped roof with north-south orientation. Stylistically, we find a low-pitched hipped roof in the Tuscan style most appealing, but it is uncertain whether this can be combined with 1.5 stories and sufficient living space.

Basement, floors: Our idea is a basement at street level and the ground floor with living space at terrace level. However, the surrounding buildings had difficulties with basement construction due to rocks. The garage, or a double garage, could possibly be integrated into the basement. The first upper floor would be the sleeping area, probably as a half-story with sloped ceilings, due to the other buildings.

Number of people, age: Currently two people (mid-30s), with two children planned.

Space requirements on ground floor (GF), upper floor (UF):
The ground floor should accommodate a large kitchen, which can be separated from the adjacent dining room by a sliding door. Additionally, there should be space for a large living room, a storage room, an office, and a small bathroom with a shower (approximately 100 m² (1076 sq ft)).
The upper floor should have a bedroom with a walk-in closet, a large bathroom, and two children’s rooms. We would like to include a sauna in the bathroom. It would also be nice to have a guest room and a fitness room, possibly in the basement.

Office: family use or home office? Home office, one person

Overnight guests per year: Approximately ten per year, as the property is quite rural and not accessible by public transport. My parents would probably use the sleeping option more frequently.

Open or closed architecture: The living area rooms should flow into each other, but we would like to be able to separate the kitchen with a sliding door. We do not like a long narrow layout connecting kitchen, living room, and dining room, as often seen in many designs. We prefer an “L-shaped” layout.

Conservative or modern construction: rather conservative (see above)

Open kitchen, kitchen island: A large kitchen is very important to us, as we both enjoy cooking. It should have a kitchen island with bar stools and a view of the garden and living area.

Number of dining seats: In the kitchen 2–4 at the counter. Our dining table seats eight.

Fireplace: Ideally in the living area, as there is a small forest with enough wood. However, we are unsure how this aligns with KfW 55 energy standards and underfloor heating, both in terms of energy efficiency and ecology. A gas fireplace or similar would also be acceptable.

Music / stereo wall: Sonos speakers are available and would be integrated.

Balcony, roof terrace: Not really necessary in our opinion, considering the large garden.

Garage, carport: Two garage parking spaces for us, preferably with a direct connection to the house. Since the current double garage of the father-in-law stands on the property and will be demolished, we have agreed to build a new double garage for him on our land, so a total of two double garages are to be built. Possibly, we would also add a carport, as this is more practical especially in summer.

Utility garden, greenhouse: We would like some raised beds with vegetables in front of the kitchen. Given the size of the plot, a further utility garden with fruit trees would also be possible further away.

The kitchen is the most important part of the house for us, so we would orient it to the south with direct access to the terrace. The dining room, separated by a sliding door, would adjoin it. The living room is planned behind this, not directly facing south. We want a large open design, but to avoid an impersonal feeling, a certain room structure should be maintained. Large south-facing windows on both the ground and upper floors are important to us, providing a nice view of the adjacent forest and fields. If the budget allows, we would also like to build a swimming pool in the garden.

House design
Who is the designer: Do it yourself
What do you particularly like? Why? Large open kitchen facing south, as well as a large open dining and living area that is visually somewhat separated.

What do you not like? Why? We are still unsure about the layout of the upper floor and the orientation of the staircase. Also, we are uncertain whether to place the entrance at basement level (street level) or on the ground floor, which would look better but would require a larger outdoor staircase.

Price estimate according to architect/planner: Between 450,000 and 700,000 (euros)

Personal price limit for the house, including equipment: We would actually like to manage with 500,000 € (euros) turnkey but will probably have to make some compromises for that
Preferred heating technology: Geothermal energy with additional solar thermal system

If you had to give up details / expansions:
- Could give up: sauna in bathroom, walk-in closet, fitness room, separate guest room (possibly use a sofa bed in the office), built-in pool
- Cannot give up: large kitchen with island, large bathroom, home office, large south-facing window front

Why is the design as it is now?
The design is our own. We also had a few sample designs created by prefab house companies and an architect. So far, however, we think our own somewhat revised design suits us best.

What is the most important / fundamental question regarding the layout in 130 characters?
The question is whether to build a basement despite the likely presence of rock. Or how to otherwise balance the height differences on the slope to keep the living area at garden level. The upper floor will have to be planned with sloped ceilings or dormers. An architect suggested split-level due to the slope, but we are unsure about this.