Floor plan, building with tree, granny flat, and existing buildings

And @ypg I mean for the KfW only one residential unit counts according to their funding guidelines,

No. You get funding for each residential unit…. What do you think is the reason why every second person plans a fake granny flat in the house here. A few years ago, some really thought they could declare their two children’s rooms in the attic as a granny flat. Meanwhile, construction is already completed, but often the office including WC is still planned inside. Rent is included in the financing, but not that they can no longer access their WC. This granny flat is in high demand. You have all the possibilities! What does your building expert actually contribute?

Washing machine and dryer can be stacked, sink will be removed (nobody needs it there), instead more space for heat pump and probably storage. Electrical installation looks huge? Does it fit? Possibly one wall-mounted drying rack. And yes, in my opinion you don’t need two dryers if you have one. A cabinet can still go into the hallway to store buckets and brooms. If necessary, the 5.60m extension depth could be extended to the full 6.10m remaining from the 15m. But it won’t become 15 sqm (which I personally also find exaggerated).

Perhaps still interesting regarding ceiling installation of central residential ventilation: was so kind as to show us his. https://www.hausbau-forum.de/threads/platzsparen-durch-deckenmontage.7729/post-87712

And, how is your [Buche] actually doing? Is there anything new?