Is it possible to divide a 40m² apartment into two units?

Dear forum!

I am considering dividing my father's apartment into two living units. The goal is to have one part basically available for myself and to rent out the other part (e.g., to a student, Airbnb, etc.). Ideally, both units should each include a bathroom with a toilet and a small kitchenette. I understand that this process will involve considerable construction work, especially since the floor plan (see attachment) is probably not optimal for this. Primarily, however, I just want to find out whether the separation is even possible structurally/plumb-wise and, if so, how.

I would be happy if you could give me feedback; I am open to any ideas!

Many thanks and best regards from Vienna!

Before I start worrying about structural issues, I would first clarify whether it is even legally permissible. On one hand, the property management might want to have a significant say, and on the other hand, the building authority could require an additional parking space.

In Germany, as far as I know, you would have to plan a kitchen and storage room for a separate residential unit (at least in terms of space). Most likely, I would see two rooms in the open-plan area so that a shared flat could be created, but I consider it utopian for two separate residential units (let alone that I am against profit maximization through AirBnB and, as far as I know, more and more cities are taking action against this misuse).

Basically, I had planned that there would still be an entrance door and that you would access the two living units through the anteroom - so basically a shared flat that each includes a bathroom and kitchenette.

I also think the suggestion of a two-room shared flat with a shared bathroom and kitchen is great! How would you arrange the two rooms?

Well, you don't have much choice when it comes to the arrangement of the rooms, both are supposed to have a window. The kitchen can of course only be relocated if water and sewage can be rerouted. It's less problematic than moving a toilet, but still sometimes difficult.

Two separate residential units are - with all due respect - a modest idea.

Well, you don't have much choice when it comes to the arrangement of the rooms, both should have a window. Of course, the kitchen can only be moved if water and wastewater lines can be rerouted. It is less problematic than moving a toilet, but can still be difficult at times.

Two separate residential units are - with all due respect - a lousy idea.

Thank you very much for the drawing. I had the same idea. What are the requirements for laying water and wastewater pipes? Or what could be the issue?

It has to flow somewhere. Wastewater that always has sufficient slope far above sooner or later almost certainly causes a blockage, and in an existing building, especially a residential complex, you cannot simply have a new downpipe installed through the floors below you.