Draft floor plan of a single-family house (convertible to a two-family house in old age) on a slope

Development Plan/Restrictions
Plot size: 440 m²
Slope: steep slope with 30° - 40° in the rear area, 7-10 m towel-shaped plateau at the street
Site coverage index: not applicable, fits.
Floor area ratio: not applicable, fits
Building window, building line and boundary: no development plan, building permit for another object already exists
Edge development: single-family house, 2 full floors, mostly gable roof, but also flat and hip roofs
Number of parking spaces: 2 are mandatory (no trapped parking space)
Number of floors: 2 full floors + partial basement on the south slope
Roof shape: gable roof
Style: free planning
Orientation: hillside location facing southwest
Maximum heights/limits: unknown
Further requirements: no development plan

Client Requirements
Style, roof shape, building type: gable roof, timeless inside & outside
Basement, floors: (partial) basement (on slope) + 2 full floors (see section)
Number of people, age: 2 adults + 2 children
Space requirements on ground floor, upper floor: approx. 85 m² per floor
Office: initially omitted, if needed in guest room or basement
Overnight guests per year: hopefully many :)
Open or closed architecture: middle way, as the two apartments should remain separable in old age on ground and upper floors
Conservative or modern construction: see above
Open kitchen, kitchen island: yes
Number of dining seats: min. 4
Fireplace: yes, in the winter garden
Balcony, roof terrace: yes, on basement level, 2.5 m facing south
Garage, carport: yes, on the east side near the house entrance
Utility garden, greenhouse: terraced garden planned with usable areas
Other wishes/special features: There should be no water connection in the basement as we want to avoid a lifting system. Therefore, the utility room is on the upper floor instead of the basement. It is located near the staircase to be usable in old age if the apartment upstairs is separated by a door.

House Design
Who designed it:
Planner of a construction company together with us
What do you especially like? Why?
Open room concept on the ground floor in combination with retreat areas on each floor. Seating window facing south (downslope), also winter garden and terrace there
What do you not like? Why?
Basement and basement shape are not quite satisfactory, but probably can’t be helped due to the location of the staircase in the stairwell.
WC & room on the ground floor are somewhat "built-in", but we cannot find a smarter solution as the access should not be via the hallway
Cost estimate: none yet
Personal price limit for the house, including equipment: as long as we stay under 5 million it’s all okay :D
Preferred heating technology: solar combined with pellet heating

What you can do without
- you can do without:
Bathroom upper floor is still very large, may be smaller
- you cannot do without:
Separability of living units for old age, seating window in the living room

Why is the design like it is now?
The plot has a towel-shaped plateau with 22 m width and 7-10 m length. The house with mass should stand on it. On the west side, a seating area/garden is to be created with access from the kitchen via a few meters of wooden terrace. The slope in the south falls steeply. On the east, the garage and a parking space at the driveway are to be built.
Windows should be symmetrical from the outside, therefore they are partially still somewhat oddly arranged on the ground and upper floors.

What is the most important/fundamental question about the floor plan summarized in 130 characters?
We want to use the plot as it is rather than working against it. The unobstructable south view should be emphasized. The sightline from the house entrance, through the hallway, glass door over the dining table into the garden to the west should make the house appear spacious and large. There are three old trees on the plot that we will integrate into the garden. Inside the house we try to keep it minimalist and still create a timeless living feeling.

We are open to all suggestions and ideas but also have concrete ideas, as can hopefully be seen from the floor plan.
Is there anything you think we still need to consider or can improve?

Thank you very much for your support :)

We would like to use the property as it is,

Great, finally someone who doesn’t violate the property.
Still, the planning is a mystery to me...!

We are open to all suggestions and ideas, but we also have concrete ideas, as you can hopefully already tell from the floor plan.

Not at all: what kind of room is that down on the left in the plan? The room with the stove... what is it supposed to be? A conservatory?
Don’t you watch TV? Shouldn’t you be able to go out through the patio doors?

The basement and basement shape are not quite satisfactory yet, but it probably can’t be helped because of the location of the stairs in the stairwell.

What is the basement for if the utility room is on the upper floor? Is this what you mean by “use the property as it is”?

WC & room on the ground floor are somewhat "blocked",

What does that tell you? To me it says: “Redesign me”

open floor plan on the ground floor combined with retreats on every floor.

I don’t see that. Well, you might want to put some more effort into the upper floor. What are those captive rooms supposed to be? I thought you were planning with two kids? No separate rooms for the little ones?
On the ground floor I don’t see the living area as a retreat: not only is it a passage room, you also have to walk behind the sofa. That’s anything but a retreat.

separability of living units for old age,

Why? For age-appropriate living in old age? The bedroom and bathroom are not age-appropriate.

I’d say you should submit the upper floor draft, in any case, also the ground floor with planned furniture.
I somehow don’t see living here, only a platform to look out from.
But that may be due to poor or no furniture planning. The questionnaire was also rather uninformatively filled out. Where are the trees drawn? Where is the terrace? Do you even want to build?

First of all, thank you for your honest opinion. To make everything a bit clearer, I have labeled the floor plans with the names of the rooms:

Why? Because of age-appropriate living in old age? Bedroom and bathroom are not age-appropriate.

Yes, the rooms are probably not yet age-appropriate, the idea is to design the wall between guest room and bathroom as non-load-bearing and to assign the corridor to the bathroom in old age, thus creating an en suite bathroom.

Otherwise, we are still grateful for alternative proposals on how to create a good and yet separable design on the property, oriented according to the sun and the plot.

Here again is the pressure of the all-in-one solution, which complicates many things.

Stairwell character of the 80s. Far from modern.
Bedroom and bathroom not accessible/barrier-free, even if the hallway is removed.

Terrace instead of garden access. With children. more than impractical. Without children unsatisfactory.
Kitchen to the outdoor dining area.
Living quiet area is in the passage.
What is the purpose of the conservatory?
Do you have a TV?

Children's room as a passage room?
What about the conservatory on the upper floor?

Shower too narrow.

Have you ever furnished the rooms with real furniture to scale?

It is good that you accept the plot and do not desperately try to fill it perfectly flat.

I would remove the obligation for a two-family house, better integrate the basement into the planning, and redesign the upper floors.

The idea is to design the wall between the guest room and the bathroom as non-load-bearing and later attribute the hallway to the bathroom in order to create an en suite bathroom.

Even then, the room is too narrow. Just take a look at the placeholder furniture – you can’t fit more in there. I don’t see a double bed with age-appropriate clearance on the left and right sides.

Otherwise, we are still grateful for alternative suggestions on how to create a good yet separable design on the property, oriented towards the sun and the plot.

Well, you have been asked several questions that perhaps need to be answered?!
If you are planning yourself, you also have to respond– or let a professional take over. From what is known about the property, I don’t see a problem building a single-family house on it...

If you panic about not getting into bed anymore with a walker or frailty, then plan the sleeping area downstairs right away: enough space on the left and right side of the bed and freedom of movement in the bathroom. And space for a wardrobe: it shouldn’t be difficult to plan a bedroom in residential construction where a double bed and a 3-meter wardrobe fit in 12 sqm.
If you really want to live in your house drooling yet, you can have a stairlift installed.

Children’s room facing the open space?

It won’t get any better if you ignore the questions asked of you (and their answers):
I don’t receive the questionnaire with the information I want! Every question is justified, and now they are missing for answering.

You have received enough feedback that you don’t address. Living area virtually nonexistent, garden access neither, just like trees.

Just as the questionnaire was only half filled out, the house looks like that – one half was neglected.

Is there anything from your perspective that we still need to consider or could do better?

Not at all, go to the architect. Your combination of a partially non-basement ground floor and a partially non-above-ground basement is unfortunately more odd than clever, and so expensive that it more than outweighs the otherwise "restrained" approach to architectural finesse. Which of the two should the planner orient themselves on: the design simplicity or the technical extravagance? – after all, these are two very different budget pairs.