ᐅ Floor Plan Discussion: Single-Family Home with Separate Apartment as a Multi-Generational House on a North-Facing Slope

Hello everyone,

I have been a silent reader here for some time. Now that we have finally secured a plot in our preferred location, we have started planning our multigenerational house (single-family home plus a 3-room secondary apartment). Unfortunately, the very small building envelope makes the planning difficult from our perspective, so I would like to present the current design here for discussion to get suggestions and tips.

Here is the list of questions:

Development Plan / Restrictions
Plot size: approx. 575sqm (approx. 23x25m (75x82ft)), access road on the north side, sidewalk and, at some distance, a street on the east side, neighboring buildings to the south and west sides
Slope: slight northeast slope, the terrain rises from the northeast corner of the plot to the southwest corner (approx. 34m (112ft)) by around 2.2m (7ft)
Site coverage ratio: not explicitly stated in the development plan
Floor area ratio: not explicitly stated in the development plan
Building envelope, building line, and boundary: building line on the north side with a 5m (16ft) setback from the road; building line for the garage on the east side right at the plot boundary; building envelope for the house is 9x12m (29x39ft), for the garage the building envelope on the east side is directly extended 3-3.6m (10-12ft) (slightly angled) to the boundary.
Edge development
Number of parking spaces: according to parking regulations, we need 4 (including space in front of the garage), but we could manage with 2-3
Number of floors: basement level plus 2 full floors
Roof type: gable roof with 15-20° pitch
Architectural style: so far, we have liked the country house style best, but we are flexible
Orientation: ridge line running east-west, rotated about 20° (clockwise) toward the west
Maximum height/limits: wall height from basement floor to roof surface 9.20m (30ft)
Other requirements: KfW40+ standard is mandatory, dormers are not permitted

Homeowner Requirements
Style, roof type, building type: see above
Basement, floors: see above
Number of occupants, ages: main house 2 adults + 2 children; secondary apartment 2 adults (should also be rentable, e.g. for 2 adults + 1 child)
Space needs on ground floor (GF) and upper floor (UF):
GF: living/dining/kitchen + guest toilet + pantry/laundry room;
UF: 2 children’s rooms + master bedroom + family bathroom;
GF or UF: office + guest room (preferably 2 separate rooms) + second bathroom (or shower in guest WC);
Basement: living/dining/kitchen + master bedroom + child’s room/office + bathroom + storage room;
Basement or GF: entrance hall for main house (with a "dirt trap")
Office: family use or home office? Home office for 2 people (4-5 days/week + 2-3 days/week)
Overnight guests per year: 2-3 times per year a “long-term guest” staying for several weeks (therefore preferably a separate guest room), plus 4-6 times per year “weekend guests”
Open or closed architecture: basically more open, but with possible retreat areas
Conservative or modern construction: no preference
Open kitchen, kitchen island: kitchen open to dining area, living room acoustically separated or separable, kitchen island optional
Number of dining seats: 8
Fireplace: yes
Music or stereo wall: no, but a bookshelf wall
Balcony, roof terrace: due to terrain, balcony at ground floor level as a substitute for a terrace
Garage, carport: single garage is sufficient
Utility garden, greenhouse: utility garden
Other requests / special features / daily routine, also reasons for or against certain elements:
The secondary apartment should be barrier-free (walker accessibility), larger sliding or double door to the living room: basically, we like an open living/dining/kitchen area, but occasionally it would be good to have some quiet in the living room while someone else is busy in the kitchen. Roof = ceiling on UF (at least for the children’s rooms), ceiling height on GF preferably a bit higher (approx. 2.70m (9ft)). The "dirt trap" in the entrance area, i.e., a hallway separated by a door from the living area, so that one does not have to pass through it again after entering and taking off shoes (e.g., on the way to the UF or to the toilet).

House Design
Who designed it: planner from a builder friend based on our sketches (they will not build the house due to distance)
What do you like most and why? Layout and number of rooms, orientation of rooms (light and street noise), kitchen with terrace access
What do you not like and why? Entrance area and stairs between basement and GF feel too convoluted and cramped, the fireplace I would like near the stairs to UF so the heat can rise + fireplace on the north side of the roof (due to photovoltaics), basement storage room too small
Price estimate according to architect/planner: not yet available
Personal price limit for the house, including equipment: 650,000 € (besides landscaping, except possibly necessary retaining walls, we can initially do without it)
Preferred heating technology: mandatory connection to district heating

If you have to give up, which details or features
- can you do without: separate office and guest room, increased floor height, connecting walkway between terraces on the ground floor
- cannot do without: secondary apartment, barrier-free living

Why is the design the way it is now? For example:
We estimated the minimum sizes for each room and arranged the rooms based on the surroundings (slope, light incidence, view, street noise). These drawings were adopted nearly 1:1 by the planner.
The sticking point from our perspective (and the planner’s too) is the entrance area, the stairs from basement to GF, and the upper hallway; these still don’t quite fit.

What is the most important basic question about the floor plan, summed up in 130 characters?
Do you have suggestions or ideas for the entrance area, the stairs from basement to GF, and the upper hallway so that the rest can stay roughly as is, or should we rethink the entire plan? General feedback on the planning?

Thank you in advance for your feedback! If I forgot any information, please ask.

I forgot to mention something:

The access road to the north is level with the building ground (BG). The road and sidewalk on the east side are currently significantly above the natural ground level and run roughly parallel to the terrain at the western boundary.

Due to the road layout on the east side, our idea is to adjust the terrain on the property to match the street level. The northeast slope would then become more of a northern slope. On the south side of the building ground, the terrain would be about 1m (3.3 ft) above the finished floor height along the entire length of the house and would then rise another 1m (3.3 ft) towards the southern boundary. On the south side, little or no excavation or retaining would be needed (depending on the window sill height). On the west side of the building ground, we would like to excavate down to ground level to create a terrace for the basement apartment. This area would require retaining to the south of about 1m (3.3 ft) in height.

How many square meters is that? Just under 240?
Building that as KfW40+ in a hillside location won’t be possible for €650,000.

The granny flat might not be suitable for a rollator. Check if a 1.5 m (5 feet) turning radius is maintained everywhere.

The house does not fit the budget. There is a shortfall of about 200,000 euros when looking at the current average prices for comparable projects.

Myrna_Loy schrieb:

The house does not fit the budget. There is a shortfall of about 200,000 euros when looking at current average prices for comparable projects.

Including the slope, I estimate the shortfall to be more like 250,000-300,000 euros.