Additional costs for residential units

But that is not permissible as an escape route. The fire department cannot ladder up to it, nor can the resident get outside through such a high window. Just plan a dormer out front, you will need it.

Yes, thanks! I also noticed that earlier when rereading the regulations. In an emergency, I had thought about a dormer/small roof terrace, but I still needed to ponder the idea a bit. I think I would only do that if I can even get approval for the 3 residential units (and nothing else speaks against it anyway: building codes, parking spaces, etc.). If that is not possible anyway, the additional escape route would not be required either (right?).
I was worried that a dormer/terrace up there would significantly complicate the insulation, so that would only be a last resort for me.

I can't start the roof on the walls and then somehow build another meter in front of that. But it probably works and I just don't get it.

Yes, that's how it is. Maybe you should find a real professional who can answer your questions at the drawing board.

To ask concretely again: Was my rough estimate of the attic area correct for such a roof design?

So if I have to subtract about 2m on each side to reach 2m height in order to use the space sensibly, then 6x6m remain. From that you subtract the staircase, walls, and shafts, leaving you with 30m². I would actually calculate so conservatively, since you also lose a lot of space due to the floor, wall, and roof structure.

So if I have to subtract about 2m on each side to reach a height of 2m in order to use the room sensibly, then 6x6m remain.

In my sketch it is 3 meters on each side to reach 2 meters. (Without a set square, mind you, so roughly estimated, WITHOUT KS in the roof) A shower needs 2.50…

Well, now I'm being mean: the centrally located staircase causes quite a bit of hallway space on the other floors. So: build even bigger and then also get more area upstairs ;)

You are probably the third this week who plans a granny flat with Pioretten thoughts at all costs, just to at least theoretically get a first taste of building a house. We're not stupid here either, even if some like to pretend so. Arguments come up... hehe, hopefully 11ant has documented it once.

I'm answering you because I can't quite assess your intention.

But let's be honest now. I understand that you don't feel like supporting anyone in subsidy fraud here. All good. But honestly, what does it achieve? The nature of some comments (especially as I said in other threads that I have skimmed through, but I have also sensed this tendency here) rather scares people away than creates an inviting, helpful, and friendly atmosphere. When in doubt, always for the accused, right? Everyone who gets properly advised here is one more person who doesn't make stupid mistakes. And if that means one more person is advised who tries to sneak around the KFW, then so be it. You don't have to be the KfW police. Especially since the KfW strictly speaking only subsidizes the potential of this living space (my current understanding). So if someone wants to build a house with 5 residential units and meets all the requirements, then so be it. I probably wouldn't want to live in that (likely completely) built-up thing, but if he sells it in the end, at least it can be used according to the rules.

Directly accusing someone (no matter who) of wanting to commit subsidy fraud and therefore no longer talking decently to them is not a viable solution either. Personally, I suspect that in the future more and more "weird birds" will appear here who want to build houses with multiple residential units: living space is getting scarcer, the dream of a single-family house is becoming more unlikely. I have lived in apartments for many years and can well imagine not having more than 150+ square meters for just 3 people myself in the future, but rather limiting myself and living in several residential units under one roof. I used to be the tenant, now maybe soon the landlord. But I still try to keep my size requirements roughly the same as before. My family situation offers such communal living; but that might not be a suitable model for everyone. You can also do it with friends or even strangers. No matter with whom: I would claim the trend is rather towards multi-family houses or "optimized living space usage." That is dictated mainly by land prices and rising construction costs for most people. And if you look at what cities mostly plan (at least where I am), those are primarily apartments and row houses. Fewer detached single-family houses. Basically, when it comes to creating living space, you can indeed be grateful to anyone who can bring themselves to no longer live alone in their own house. Personally, I wouldn't want to do it with strangers right now either, but others are surely less sensitive about that. In summary, I can only advise: take courage and help the questioners. You have the knowledge, they don't. A lot is changing right now, KW40+ is becoming more "normal," and I don't think everyone who plans a granny flat is automatically a nasty subsidy fraudster. Maybe such plans (and such questions) are simply the logical consequence of the circumstances regarding climate and market that are currently emerging.