ᐅ Floor Plan for a Multi-Generational Home on a Challenging Plot of Land

Hello everyone,

I am currently considering building a multigenerational house together with my parents. We have a plot of land available (about 700m² (8,350 sq ft)) in a location we really like, but the shape of the plot is unusual and presents some challenges for the initial planning.

I hope to get some ideas from you that might lead me in completely different directions. I keep coming back to the same solution (I have included a very rough draft below): From the street view, a single-family house with a garage to the right, and at the back an accessory dwelling unit (ADU) as an extension.

We’ve already had several discussions with my parents and know what kind of solution we envision. Fortunately, there is no pressure or obligation that an additional unit must definitely be included. However, we can well imagine it if these conditions are met:

• Separate entrances on different sides of the building
• The terraces of the single-family house and the ADU should not be directly adjacent; preferably separated or around the corner
• Windows of main living spaces (living room, kitchen, etc.) should not face into each other’s garden

This should not be understood as us wanting no contact or view of each other. We already live together under one roof without any issues. But we would like to implement the points above. Also to be able to rent out the ADU to “outsiders” in a few decades, if needed.

The rough draft basically shows a classic single-family house with a detached garage. The kitchen and living room face south/west towards the garden. Behind the garage is an extension (single story only, possibly flat roof) that partially overlaps with the main house. The living/kitchen area is in the northern part, with the possibility to place a terrace in the designated cutout (to keep within the 3m (10 ft) limit). The bedroom is located by the wall next to the garage; the bathroom roughly beneath the “9.5m (31 ft)” dimension.

What I like about this draft:

• Structurally and physically separated; from the street, the extension is barely visible; it still looks like a “normal” single-family house
• Separate outdoor areas in the garden
• The possibility to drive past the single-family house on the left into the garden (especially useful with a trailer for garden work, etc.)

What I’m not so happy with:

• I struggle with the idea of not allowing my parents proper south/west-facing windows in this design
• The described bathroom with an existing window would look directly into our garden

I look forward to more ideas, especially completely different approaches. As I said, I fear I’m a bit “blind” at this point. I hope this “draft stage” is okay—I haven’t dared to start interior planning until the basic structure is more satisfactory.

MidnightBlack schrieb:

I hope this "design phase" is acceptable – I haven’t started interior planning yet since the overall structure is still not satisfactory.

The basic structure will change and must change because an open floor plan usually defines the framework of the building footprint.
As far as I know, due to fire protection regulations, windows of residential units must be at least 3 meters (10 feet) apart, meaning they cannot be located around corners. Your floor plan will therefore have to compromise on window placement – either for the main house on the west side or for the secondary apartment in the southwest.
Since you are essentially combining the units into one block, you lose valuable window area in both units. In that case, you might as well consider building a semi-detached house with more defined structure and equal conditions for the terrace and similar features, ideally oriented southwest, with one garage at the back and the other at the front. The secondary apartment section would be smaller.

I would first focus on placing the garage adjacent to the property boundary. Between the house and garage, you can create a courtyard that provides access to the secondary apartment. Alternatively, you could position the secondary apartment at the front and have parking spaces at the rear.
What does the zoning or planning permission say about the floor area ratio and related regulations?

@MidnightBlack
Your willingness to discuss does not lead you to a solution, nor is that the purpose of a forum. You need to speak up at some point 🙂

ypg schrieb:

@MidnightBlack
Your willingness to discuss doesn’t necessarily lead to a solution, nor is it the main purpose of a forum. You do need to speak up at some point 🙂

Well, I think it’s okay if it takes a bit longer before that moment comes.

Regarding the matter:
An arrangement that provides as much privacy as possible for both parties is generally a good idea. The layout you drew, as mentioned by @ypg, will likely cause problems either during the building permit / planning permission process or later when renting out (in Cologne, for example, even apartments with a purely north-facing orientation are not allowed to be rented, even if they are quite bright due to a large window front).

The first idea that comes to mind is an asymmetric semi-detached house with staggered units (one “half” is simply smaller).

Are there elevation differences on the site that could be utilized? A three-dimensional approach offers additional possibilities for creating privacy.

I also thought of a small penthouse with a rooftop garden on top of a bungalow. This will probably not be cost-effective to implement.

hampshire schrieb:

Well, it’s okay if it takes a bit longer until the beep, in my opinion.

Yes, but he still has his first question open in this forum, which he has not followed up on. And if someone is already visibly “active” here, then they should maintain their own threads as well. The original poster is reading along, is logged in multiple times for posts, but just doesn’t engage in discussion. I wouldn’t say anything if this wasn’t noticeable.

Hello,

ypg schrieb:

To my knowledge, due to fire safety regulations, windows of residential units must be at least 3 meters (10 feet) apart, so they are not allowed to be positioned at corners. Therefore, your floor plan will have to compromise on window placement – either the main house on the west side or the granny flat in the southwest.

Okay, I wasn’t fully aware of that. When I designed the concept, I had a floor plan like this in mind: ProGeneration 132-47/20 from fertighaus.de (I believe external links aren’t allowed here?). I originally didn’t plan on corner windows. A 3-meter (10 feet) distance between windows would definitely be feasible.

ypg schrieb:

Since you are basically combining the units, you lose valuable window space in both. In that case, you might as well build a duplex with more structure and consistent conditions for the terrace and so on, for example with southwest orientation, one garage at the back, the other at the front. The granny flat would be smaller.

Yes, that’s true. This is indeed a challenge for me. We deliberately do not want to build a semi-detached house. Firstly, the smaller apartment should be entirely on one level as much as possible. Secondly, we are not attracted to “traditional semi-detached houses” at all. The option to build a “true” granny flat fully integrated in the ground floor, with the upper floor belonging completely to the main house, also does not seem optimal since we want to have as much living space as possible on the ground floor. Therefore, the basic approach is to have two separate building volumes that overlap.

ypg schrieb:

What does the zoning plan say about the floor area ratio, etc.?

The floor area ratio is 0.4 – although we might be able to play around a bit with the plot size.

ypg schrieb:

@MidnightBlack
Your willingness to discuss won’t by itself lead you to a solution, nor is that the sole purpose of a forum. You need to make a concrete statement at some point 🙂

That’s true. I have read your replies but haven’t had the chance to respond properly yet. Regarding my other thread: I was very thankful for the initial advice there, too. However, it's currently difficult to work on financing as it’s unclear whether we will build a single-family home or a single-family home plus granny flat. That definitely affects the investment scope 🙂

hampshire schrieb:

The first thing that comes to mind is arranging them as a staggered, asymmetrical semi-detached house (one “half” simply being smaller).

Is the sentence incomplete? Are you making an observation, or is it a suggestion? ;-)

hampshire schrieb:

Are there any changes in elevation on the site that could be used? A third dimension offers additional possibilities to create privacy.

No, there are no elevation differences.

Are there any other possible solutions or floor plans that could serve as a pool of ideas?