Stepped floor house 23x30m plot with floor area ratio 0.25

Good day dear forum users,

My wife and I are about to purchase a plot of land. We have a civil engineer at hand who designs single-family homes and lives just around the corner, who is working out the detailed planning for us and accompanying the construction. However, the development plan presents a hurdle for us, as the designated site coverage ratio is only 0.25. Furthermore, our goal is to create a lot of living/work space on the ground floor, which is difficult with 684m². What especially concerns us is the space requirement for ancillary facilities. Maybe you have some ideas? We would be grateful for anything! I would like to point out that my wife and I are complete laypersons.



Development Plan/Restrictions
Size of the plot: 684m²
Slope: approx. 1m drop over 23m and 0.5m over 30m
Site coverage ratio: 0.25
Floor area ratio: 0.5
Building window, building line and boundary: 5m from the street, otherwise free
Edge development: garages may be built up to the boundary
Number of parking spaces: double garage + 5m driveway (3m area in front of the garage is fixed by the development plan) in front
Number of floors: up to 2 full floors
Roof shape: no specification
Style: no specification
Orientation: no specification
Maximum heights/limits: no specification
Further requirements: only detached houses, one tree of a certain size per 300m² of started area, separated sewage system
Neighbors to the left, top, right, street below without restrictions such as planting islands etc.


Requirements of the builders
Style, roof shape, building type: recessed top floor with pitched roof or flat roof
Basement, floors: no basement due to ground class up to 7, 2 full floors
Number of people, age: 2 adults, 1 child
Room requirements on the ground floor: living, dining, cooking, guest, office, WC/shower, utility room/HAR, access to the garage OG (upper floor): 2-3 rooms + 1 bathroom
Office: family use or home office? Both
Overnight guests per year: approx. 5-10
Open or closed architecture: open
Conservative or modern construction: modern
Open kitchen, cooking island: island preferred
Number of dining seats: 6-8
Fireplace: no
Music/stereo wall: no
Balcony, roof terrace: possible as an extra but only if the budget allows
Garage, carport: double garage
Utility garden, greenhouse: no utility garden planned
Further wishes/special features/daily routine, also reasons why this or that should or should not be


House design
Who is responsible for the planning:
-Do-it-Yourself
-Living area/usable area approx. 211m²

What do you particularly like? Why? My wife and I would like two additional rooms on the ground floor to have office and guest space somewhat separated from the private sleeping area. Also, the south-west side with the living areas is beautifully sunlit. The extra room upstairs is intended as a craft/music room (drums and piano) or as a backup for child 2.
What do you not like? Why? The only negative point would be the somewhat sparse light in the office, which I could overlook.
Price estimate according to the architect/planner: not yet available.
Personal price limit for the house, including equipment: €470,000
Preferred heating technology: heat pump (due to the small plot, air-water)


If you have to forgo certain details/expansions
-What you can do without: hard to say, since the ground floor layout is already so compact anyway. Possibly the technical room on the ground floor, but I also find relocating it to the smaller upper floor problematic.
-What you cannot do without: 2 additional rooms on the ground floor.


Why has the design become what it is now?
Since it is a completely newly established residential area, exemptions are off the table. Due to a change in my professional field, there is a need for an office. Because this is in a granny flat, additional funding from KFW would even help here. As a basis, we took a floor plan from Fischerhaus, rotated and mirrored it to optimize the position on the plot.
What makes it particularly good or bad in your eyes?
We think it is good because a relatively large usable garden area remains, with still good light yield. Access to the front door would now be a negative point, but some compromises have to be made in planning. On the other hand, you have a relatively well-separated garden. Also, there is the access through the garage into the house to avoid unnecessarily long distances when unloading.


What is the most important/basic question about the floor plan summarized in 130 characters?
Currently, we only have about 20m² left for the approach to the house and terrace. Do you see potential for optimization here, or should we revise our wishlist and possibly start again?

Best regards

Sarah and Christoph

What about ancillary construction costs? Are they included in the budget? How much personal contribution do you want to provide? Why a granny flat? Considering budget and space, I would reduce the floor plan or make the footprint smaller and 2 VG

The property will be financed by us with our own funds, as well as the incidental acquisition costs. We would do the entire electrical installation ourselves, as well as the interior painting and floor coverings except for tiles. The exterior facilities will also be largely done by ourselves. Please excuse me for forgetting that.

The other incidental construction costs are included in the budget.

The reason for the granny flat is that, on the one hand, we do not have major disadvantages from it. Except for the kitchen installation and an extra WC with a small shower. But we are able to use the KfW loan twice and thus potentially receive the repayment grant twice. This would mean that nearly half of the financing framework would be a KfW loan, of which up to 60,000 could be repaid under KfW 40+ if the energy standard is achieved. In the long term, many options remain open for us, e.g., au pair, grandparent living with us in the house, or living on one level in old age. And I would already use the large office now.

EDIT: I have to say that building again later is not an option for us at first.

Later in life, living on one level with the floor plan won't work. As long as you are mobile, everything stays as it is anyway, and for later there are stairlifts and other solutions. The stairs are often the smaller problem.

I would remove the guest room. For 10 times a year, the visitors can sleep in the second, just-in-case room upstairs. I would also remove the granny flat concept. Reducing the floor area would also be possible. This way you have more space for access paths and the terrace.

The 2nd residential unit requires more parking spaces - more parking spaces require a higher land use coefficient. Look up whether 1 or 2 parking spaces are necessary for the granny flat and what they should look like.

Merciful goddess, what confusing drawings. Pointless dimension lines, but without any recognition of the location of the setback floor relative to the ground floor. I read the combination of low floor area ratio with the permitted two full floors (and finally also a floor space index = double the floor area ratio) as the exact opposite of an invitation for the setback floor. The living-kitchen-hallway with the adjacent WC and utility room would already be a big minus on its own, but the bottleneck transition to the small living room seals the deal for me to suggest a complete relaunch. The enclosed dressing room may gladly be discarded in the process. I believe this is also the first time I've seen a dressing room with a corner window. For a study with a CAD program, that's quite nice, but still far from building-ready.

I find the ground floor a bit cramped. I don't see a separate apartment working with 3.5sqm WC/bathroom, no space for a bed, and kitchen area with TV corner will also be difficult.