Floor plan design for a single-family house with a granny flat

If you really want to plan a genuine eligible granny flat, then you need an architect. A separate entrance could indeed be arranged, since the utility room can be located outside the main living unit and therefore a second front door would be possible, but where would the wardrobe in the main apartment go then? Your routing for water and wastewater is absurd. For example, the water pipes for the kitchenette of the main apartment are located in the wall at the head of the bed of the granny flat. A planner would have designed the two kitchenettes parallel to each other. And so on and so forth. Round shelf.

It may be that some people have mixed up quite a few things.

No. Regarding the KfW: you are mixing something up:

I had written that the granny flat was built in accordance with KfW compliance. It says in the credit information sheet: "Residential units are spaces located within a self-contained context and intended for permanent residential purposes in residential buildings, which enable the running of a household (own lockable entrance, rooms, supply connections for kitchen/kitchenette and bathroom/WC)." Nothing more and nothing less.

Because _that_ is not the definition of a granny flat!
The KfW information sheets are neither a lexicon nor Wikipedia. What you cite here from the information sheet for experts is only the definition of the self-contained nature of a residential unit. And that does not explicitly concern granny flats, but all buildings, e.g. commercial buildings with residential units. Information sheets are not meant to explain everything but to regulate so that the expert has something in hand. The building authority checks anyway.
And the self-contained nature is, as everyone here sees except you, simply not given.

In principle, independent household management must be guaranteed in a granny flat. Simply put: shower/WC, space for cooking and dishwashing facilities, and space for food storage (refrigerator) and washing and drying options for laundry. Of course, a table with chairs, a bed and a wardrobe. A storage room and a parking space for a vehicle also belong. 23 sqm or 26 sqm as a minimum size are not fixed, but of course you must clearly recognize independent household management in the plans. That is not given with only a double bed and a shower-WC setup.
I think it should be clear to you what independent household management means: going to work, cooking warm meals, personal hygiene, being able to sit normally and sleep. TV is probably regulated too: everyone has a right to TV, so you have to be able to do that in the room as well.

Wall thickness: What do you mean by that, ypg?

Well, the blunt application of 17.5 cm or less or more does not make sense. Load-bearing walls//non-load-bearing walls…

Size of children's room (ypg): matter of opinion, we find just under 13 m² sufficient, our children don’t need a ballroom.

But I did not criticize that! I wrote _in relation to_, see below

Children’s room too small in relation,

Or do you mean the missing almost one centimeter of plaster?

Certainly not. I’m thinking in RBM.

Matter of opinion, we find just under 13 m² sufficient,

And if one analyzes your sufficient 13 sqm closely, your 13 sqm are actually 12.5 and with plaster only 12 sqm. By the way, you don’t earn any praise with an “adequate”. 13 sqm are okay in my eyes if the house is planned accordingly — but with “external granny flat” and 22 sqm bedroom it is simply not well planned.

Summary: I fully agree with subsidies for residential units to create a win-win situation in a welfare state for everyone.
But catching subsidies without actually creating living space is just as lousy as grabbing Hartz IV or similar monthly benefits without wanting to work.
And yes, it is demonstrably fraud. It’s always bad when you have to write such a thing because a questioner doesn’t even put his head to work and want to comply with rules themselves.

And yes, currently everyone from the mortgage lender to the real estate portal to the construction company is advertising with the easily installed granny flats. As a result, the houses become larger and more expensive, and prospective buyers are led to dream big, as the additional costs are not only essentially subsidized but also partly financed by others. This is advertising aimed at generating more margin and sales in lean times. Don’t be seduced, but get good advice. Subsidies are no longer distributed as generously as they were before all the crises. The federal government wants to see results for the subsidy amounts – and these are not generous guest areas. The construction industry is currently in a state of panic and is increasingly unscrupulous, as long as the customers are online.

That means it must meet all requirements for fire protection and sound insulation

In my opinion, these requirements do not need to be observed for a granny flat, that is, a secondary apartment. It would be good to do so - already in one's own interest - but it is not necessary. After all, it is not a two-family house where you might want to sell the second unit later.

In my opinion, these requirements do not need to be observed for a granny flat, i.e., a secondary suite. It would be good, especially in one’s own interest, but not necessary. After all, it is not about a two-family house, where one might want to sell the second unit later.

We have been planning since last year to accommodate the mother nearby. Fortunately, without too much time pressure. We have explored all options with an architect, from the granny flat to the tiny house to the conversion of an outbuilding. A major topic was also which measures would be necessary to get the granny flat approved as such. This included, among other things, soundproofing and fire protection. For example, a second escape route must always be provided – which would not have been the case for us without an external staircase – but that would have violated setback requirements. And yes, we are still not finished with the planning, as everything would become very, very expensive.

Believe me, you are not smarter than the rest of the world...

But this must stay between us.

@11ant: No, these are not one-meter contour lines! From the very north to the very south in order: 310 m above sea level, 309.5 m, 309 m, 309 m, 308 m, 308 m, 307 m. That means the entire house with terrace and garden is located in the range of 309.25 m to 308 m above sea level. As you can see, I don’t have to pretend the plot is flat *g* And then to your second misjudgment (I’ll call it, based on your statements, the Cinderella-nanny tale): No, the upper floor was not planned after the ground floor, but hand in hand: Children’s room in the bright and scenic south, office for working during the day in the southeast, bedroom for morning sun in the east, bathroom with large fixed glazing in front of the bathtub to the north with a view of the free undeveloped sprawling field, the same applies to the landing with large fixed glazing in the staircase, utility room in the west with optional access to the walkable carport. Where exactly is the sin here?! I quote: “Dialogue can obviously not only mean applause.”

I hoped that after the long break you would come back with a legible "surveyor's plan"...

@hanghaus2023: Your plan is quite nice, but it does not work for several reasons: The west side is the only side where houses stand, thus unsuitable for a terrace. To the north is open field, to the south/east a free view into the sprawling valley. The road in front of it (your planned driveway) is a dead end and we are the last house, after that it turns into a field path. Accordingly, our house orientation is already perfected (see above). Besides, your planned entrance in my opinion is way too acute-angled; I wouldn’t want to constantly drive or maneuver my car in there. As I said, well-meant, but unfortunately not suitable for our plot.

... and a proper briefing of those willing to help with facts is generally a powerful lever.

I can only agree with my predecessors. An granny flat will not work like that. Keyword: subsidy fraud. [...] To me it looks like amateur planning. Please press the RESET button, find a new planner and be open to new ideas. The plot seems to have potential.

Oh, who are we to arrogate Kantian standards here for a genuine granny flat? – The OP interprets the funding conditions as rules for a subsidy fraud game and gambles on being rewarded accordingly for their, in their opinion, letter-perfect compliance. Living in an amateur plan would be regarded by him as a just punishment... all good! The onlookers have long understood (or never doubted) that such an evening-dress handbag of course would never serve as a REAL granny flat. And the OP himself does not even seriously want to cram a nasty stepmother in there. So all the fuss is unnecessary.