ᐅ Step townhouse on a 23x30 m lot with a floor area ratio of 0.25

Hello dear forum users,

My wife and I are about to purchase a plot of land. We have a structural engineer nearby who designs single-family houses and who is preparing the detailed planning for us as well as providing construction support. However, the zoning plan presents a challenge for us, as the designated site coverage ratio is only 0.25. Furthermore, our goal is to create a lot of living and working space on the ground floor, which is difficult with 684m² (7368 sq ft). The main issue for us is the space required for ancillary facilities. Maybe you have some ideas? We would be grateful for any input! I must admit that my wife and I are complete beginners.



Zoning Plan / Restrictions
Plot size: 684m² (7368 sq ft)
Slope: approx. 1m (3 ft 3 in) drop over 23m (75 ft), and 0.5m (1 ft 8 in) over 30m (98 ft)
Site coverage ratio: 0.25
Floor area ratio: 0.5
Building setback lines: 5m (16 ft 5 in) from the street, otherwise unrestricted
Edge development: garages may be built up to the boundary line
Number of parking spaces: double garage + 5m (16 ft 5 in) driveway (3m (10 ft) area in front of garage is defined by zoning plan)
Number of floors: up to 2 full stories
Roof shape: no specifications
Architectural style: no specifications
Orientation: no specifications
Maximum heights/restrictions: none specified
Other requirements: only detached houses, one tree of a certain size per 300m² (3230 sq ft) of developed area, separate wastewater system
Neighbors: on the left, top, and right; street at the bottom with no restrictions such as planting islands or similar



Client Requirements
Architectural style, roof shape, building type: stepped floor with pitched roof or flat roof
Basement, number of floors: no basement due to soil class up to 7, 2 full stories
Number and age of occupants: 2 adults, 1 child
Ground floor space needs: living, dining, kitchen, guest room, office, WC/shower, utility room, access to garage
Upstairs: 2-3 rooms + 1 bathroom
Office use: family usage or home office? Both
Overnight guests per year: approx. 5-10
Open or closed layout: open
Conservative or modern construction: modern
Open kitchen, kitchen island: island preferred
Number of dining seats: 6-8
Fireplace: no
Music/sound wall: no
Balcony, roof terrace: possible as an extra, but only if budget allows
Garage, carport: double garage
Utility garden, greenhouse: no utility garden planned
Additional wishes/special features/daily routine, reasons for choices: welcome



House Design
Who designed it:
- Do-it-Yourself
- Living/usable area approx. 211m² (2271 sq ft)

What do you particularly like? Why? My wife and I would like two extra rooms on the ground floor to separate the office and guest room from the private sleeping area. Also, the southwest side with the living areas is pleasantly sunlit. The additional room upstairs is intended as a craft/music room (drums and piano) or as a backup room for child 2.
What do you dislike? Why? The only downside is the somewhat limited natural light in the office, but I think I can overlook that.
Estimated cost according to architect/planner: no estimate yet.
Personal price limit for the house, including fittings: €470,000
Preferred heating technology: heat pump (due to the small plot size, air-to-water)



If you have to give up on anything, which details/extensions
- can you do without: hard to say, as the ground floor layout is already quite compact. Possibly the technical room on the ground floor, but relocating it to the smaller upper floor also seems problematic.
- cannot do without: 2 additional rooms on the ground floor.



Why is the design as it is?
Since this is a completely new residential area, exemptions are out of the question. Due to a change in my professional field, there is a need for an office. Since the office is in a separate apartment, it could even qualify for additional KfW funding. As a base, we took a floor plan from Fischerhaus, rotated and mirrored it to optimize the position on the plot.
What do you think makes it particularly good or bad?
We like it because there is still a relatively large usable garden area, combined with good daylight. The only negative point is the access to the front door, but there’s always a trade-off in planning. On the plus side, the garden is quite well separated. Also, there is access to the house through the garage to avoid unnecessarily long trips when unloading.



What is the main/fundamental question about the floor plan in 130 characters?
We only have about 20m² (215 sq ft) left for the access path to the house and terrace. Do you see optimization potential here, or should we revise our wish list and possibly start over?

Best regards

Sarah and Christoph

What about additional construction costs? Are they included in the budget?
How much personal contribution do you plan to provide?

Why include a granny flat / accessory dwelling unit?

Considering the budget and space, I would reduce the floor plan size, meaning a smaller footprint and two full stories.

The plot will be financed by us using our own funds, as will the incidental acquisition costs. We plan to carry out all the electrical installation ourselves, as well as the interior painting and floor coverings, except for tiles. The exterior landscaping will also largely be done by ourselves. Please excuse me for having forgotten to mention this.

The other incidental construction costs are included in the budget.

The reason for the separate apartment is that, on one hand, we don't face major disadvantages from it, apart from having a kitchen installation and an additional bathroom with a small shower. On the other hand, this allows us to apply for two KfW loans and potentially receive two repayment grants. This means that nearly half of the financing framework would be a KfW loan, with up to 60,000 euros repayable under the KfW 40+ standard, provided the energy efficiency standard is met. In the long term, many options remain open for us, such as hosting an au pair, having a grandparent living with us in the house, or living on one level in old age. I would already start using the large office now.

EDIT: I should add that building again later is not an option for us.

Living on one level later in life with the current floor plan won’t be feasible. As long as you remain mobile, things will stay the same, and for later on, there are stairlifts and other solutions. The stairs are often the lesser problem.

I would eliminate the guest room. For about 10 times a year, visitors can sleep in the second, spare bedroom upstairs. I would also remove the accessory apartment concept. Reducing the building footprint would then be possible as well. This would give you more space for access paths and the terrace.

A second dwelling unit requires additional parking spaces – more parking spaces means a higher floor area ratio. Check whether one or two parking spaces are required for the accessory apartment and how these must be designed.

Good gracious, what a confusing set of drawings. There are pointless dimension lines, yet no clear indication of the location of the setback floor relative to the ground floor.

The combination of a low site coverage ratio with the permitted two full floors (and ultimately a floor area ratio equal to double the site coverage ratio) reads to me as the exact opposite of an invitation for a setback floor. The open-plan kitchen-living hallway with the adjacent WC and utility room is already a big drawback, but the bottleneck transition to the small living room pushes me to suggest a complete redesign. The trapped walk-in closet can definitely be discarded in the process. I think this is also the first time I’ve seen a walk-in closet with a corner window. For a study created with a CAD program, it’s fairly nice, but it’s nowhere near ready for construction approval.

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I find the ground floor a bit cramped.
I don’t see a separate apartment working with only 3.5 sqm (38 sq ft) for a bathroom/WC, no space for a bed, and fitting a kitchen area with a TV corner would also be difficult.