Single-family new building: Planning a granny flat for future family expansion?

I think we are still talking about ... https://www.hausbau-forum.de/threads/grundrissplanung-efh-auf-grossem-Grundstück-mit-hanglage.41063/ ... so old wine with a new thread title.

I was not aware that you cannot ask multiple questions in parallel in this forum ;) The topic of this thread is completely different and also related to a specific question. We have already taken note of the (partly) constructive criticism and are currently planning a bit anew (hence among other things also the question asked here). But thanks for your (unfortunately somewhat polemical) remark... :rolleyes:

That's how it is. Therefore: If the goal is to do something good for the children or, for that matter, one's own parents, then go ahead. The goal of obtaining partial financing for one's own construction through this should better be abandoned immediately.

I find this a good summary of the various contributions, thanks!

But do the costs really outweigh rental income and additional subsidies?

No.

I am confused. The only "luxury" would be just an additional small kitchen.

A separate living unit, which is also supposed to be subsidized, requires an adequate bathroom, a kitchen, bedroom, living room, a hallway, a storage room with washing machine connection, a separate water meter, a small outdoor area, an additional staircase, another house entrance, and a parking space. Also a few nice extras that sweeten the bitter pill that the landlord lives next door a bit.
If the target group is a couple, then provide two parking spaces. If you live in the sticks, you won't lure any students.

also selbst als barrierefreien Alterswohnsitz.

If the granny flat is also supposed to be barrier-free, then plan for 30% more floor space for the apartment, because barrier-free is expensive and consumes space. It also has to be wheelchair- and care-friendly.

sondern diese in der Zwischenzeit ggf. gewinnbringend zu vermieten.

What do you mean by meantime? Do you think you can just terminate the apartment lease if your child planning works out?

Aber es geht ja, wie gesagt, ums Souterrain.

And then also a basement.. nobody moves in there voluntarily, unless he wants nothing to do with people, is a light nerd, and listens to weird music ;)
All in all, you want to move into this basement apartment yourselves, which is supposedly going to be built to accommodate only one tenant?!
I wonder where you want to put your fitness palace then :oops:

Would you have stylish living space and enjoy international contacts and someone (YOU) who always takes care of the proper preparation of the apartment, I would recommend you to use it as a holiday apartment, but you also have to want and be able to do that, because here too it applies that you cannot just make a few euros on the side. If you make it nice, you get good money from renting and holiday apartments. If you don't do it (shady basement apartment), you don't get anything decent back either, it's quite simple.

A classic granny flat cannot simply be connected to the main apartment and inhabited by a baby and toddler. At least not with the comfort and practicality of a family house. First, you invest money for 2 living units, then you invest money to somehow create 1 from 2.

It's not about just "doing it" casually. But I feel like my description of the planning wasn't fully understood and I haven't really been given a new argument against it yet.
Planning is more difficult, that's true. But as I said, it's about the basement. Therefore, the separability and planning is not more complicated than without a granny flat.
And kitchen+bath as additional cost factors are clear to me. But do these costs really outweigh rental income and additional funding?

I would move the granny flat to the attic. 2-3 rooms, hallway, kitchen, bath.
Think about having the luxury parent area with shower and dressing room on the ground floor.
You have a big plot. Then you simply build 150m2 on the ground floor and, depending on the development plan and house shape, 110-150m2 on the upper floor.

nvm. I just read the thread with the sloping site now.
The question is, what is the focus.
Efficiency (financial) or luxury?
A third residential unit for employees is also cool!