Additional costs for residential units

A dwelling unit is a dwelling unit that can be occupied. The term itself already says that. You don’t have to provide a kitchenette to a tenant, but the connections—this also applies to other apartments. A separate dwelling unit is subject to requirements that do not need to be listed separately, because the requirements for living spaces apply, also regarding fire protection, second escape route, heating, etc. An attic usually does not meet these requirements. You do not need a separate electricity meter for a granny flat. In most residential areas, a maximum of 2 dwelling units may be built in a “single-family house.” From 3 onwards, the regulations for apartment buildings apply -> bicycle parking spaces, parking (already mentioned), laundry drying area, etc. Costs: you don’t get anything for free! For more precise prices, you need to ask your BU or architect. Exactly: you do not get a repayment grant.

A separate residential unit is subject to requirements that do not need to be listed separately, because requirements for living spaces apply, also regarding fire protection, a second escape route, heating, etc.
An attic usually does not meet these requirements.

In what way does an attic not meet these, but an upper floor does?
For example, I lived for a long time in a multi-family house with a total of 8 units spread over 4 floors. The only escape route was the stairwell and the front door on the ground floor. That seemed to be allowed without issues.
How would this differ (regarding escape route/fire protection) from a new building with 3 residential units (one on each floor) that has a central stairwell accessible from all 3 units? The exit is then just at the very bottom on the ground floor.

A separate meter is not required for a granny flat. In most residential areas, a maximum of 2 residential units are allowed in a "single-family house."

This was the point of my previous question: Is there a difference between a granny flat and a residential unit? So, for example, would it be possible to build a house with 1 residential unit and 2 granny flats, while 3 residential units often cause problems?
Or put another way: Is every granny flat automatically also a residential unit (and the same requirements apply)? Or is a granny flat something like a simplified residential unit where fewer things need to be considered?
I would find it strange then that the KfW (as far as I understand) subsidizes a granny flat the same way as a separate residential unit.

A residential unit is an apartment where a household can live. This includes a single-family house, an apartment, a granny flat, etc.

Strange I would find then,

Why? Subsidies are provided for generated, i.e. created living space, therefore also the requirement of construction completion!!!

So it would, for example, be possible to build a house with 1 residential unit and 2 granny flats, while 3 residential units often cause problems?

1RU + 2 granny flats = 3RU

The only escape route was the staircase

Even if I don't know what the house looks like, I assume your apartment was not in the attic, and if it was, then with dormers or at least one window that served as a second escape route. Many regular windows are a second escape route, a roof window is not.

Many questions - in short: do not expect "discounts," that any prices or other expenses would decrease progressively; the third residential unit "costs" exactly the same per square or cubic meter as the first one in every way. This applies down to details such as parking spaces, and even three apartments on the same downpipe are not a leap in efficiency. Escape is only salvation by one’s own power; alternatively or substitutively, external rescue must also be possible (and simplified, a firefighter with breathing apparatus must be able to fit through a window for that). In all this, it is also not yet differentiated whether these are family or single apartments.

KfW40+ also separate residential ventilation.

For parking spaces, there are usually 1.5 spaces per residential unit.

Etc.

1WE + 2 Einliegerwohnung = 3WE

All right, so basically there is no distinction. Each Einliegerwohnung would also be a fully-fledged residential unit and must meet the same requirements. Then it also makes sense that the KfW subsidizes them in the same way.

Even though I don’t know what the house looks like, I assume your apartment was not in the attic, and if it was, then with dormers or at least one window that served as a second escape route. Many standard windows are second escape routes, a roof window is not.

Okay, that’s what you meant. I just checked, sloped roof windows are valid (even if they have to meet certain requirements). So at least that’s not a problem.

For parking spaces, it is usually 1.5 spaces per residential unit...

Good tip! I have to ask about that on site. I just read that it varies a lot and some municipalities apparently don’t have any minimum numbers for parking spaces at all.

Many questions – in short: don’t count on “discounts,” that any prices or other costs would become degressive; the third residential unit “costs” exactly as much per square or cubic meter as the first. This applies down to details like parking spaces, and even three apartments on the same downpipe are not an efficiency gain.

I didn’t expect “bulk discounts.” I rather wanted to approach it the other way: What can I do myself in planning to make several residential units as cost-efficient as possible? For example, stacking bathrooms and kitchens on all three floors. Does that help? Or is it completely irrelevant in terms of construction costs? Are there any other tips to consider for 2-3 residential units to keep the price down?