Floor plan design single-family house on a slope, granny flat, double garage

And the 50s don't have to be bad - back then, buildings were very compact. Open floor plan - the notorious all-purpose room - can quickly become outdated again due to its disadvantages and often only conceals very small floor plans. I would always keep in mind how rooms can be partitioned again if necessary without losing quality.

You already recognize the difference. I’ll ask just to be sure: Are you allowed to run a business in your two-family house in that development area? Besides, KfW funding does not apply to businesses in my opinion? Where are the parking spaces for the second residential unit? And/or those for the business? I just hope you don’t get a loan from the bank. Otherwise, there will soon be one more shell construction on the market. In my neighborhood someone also has a massage practice on the ground floor. They themselves live in the attic. That can also work financially for you. But on a slope, that only works if you forgo the roof and the garage or at least convert them into a carport.

We had this question answered by the responsible building authority + district office. We have the statement that we are allowed to run a "business" on our property. The property is not in any development area. It was originally used as a meadow and has been available for development for over 20 years. The KfW funding only applies to a granny flat, yes, so we will initially declare our building project as such and then integrate a practice afterwards. As parking space, I see the possibility to park two cars in front of the garages. Additionally, there would still be the possibility to provide more parking spaces between the street and the house wall. I think that would be sufficient?

You can find out how parking spaces must be designed in the parking space regulations of your municipality.

That is not so easy - parking spaces must be proven when applying for the permit. And about [Fördermittelbetrug] I won’t say anything.

Are the rooms in the basement even accessible? To my knowledge, this is a requirement for approval as rooms for practicing a healthcare profession. The change of use must also be reported to the building authority and at the latest by the tax return, the conflict between KfW funding and workspaces can become tricky.

And about the grant fraud, I won't say anything.

That's exactly what you should do. The original poster probably doesn't realize that.

Why do you think I asked?

You can't be that naive.

I would like to help, but in this case, I'd rather stay out of it.