I spoke of total costs. On the one hand, I assumed that if you build so large, there would also be somewhat higher-end fixtures. That means I wouldn’t calculate with only 1600€. (Sauna, fireplace). On the other hand, your total does not yet include incidental construction costs, garage, outdoor facilities, etc. Is it even certain that you comply with the floor area ratio and that a two-story building is allowed on your property? Regarding the structural engineering: As I said, I am a layperson and can only guess. I’ve heard that ceiling spans can reach around 7 meters. If you have more, you need load-bearing walls. Your living room is very large, so I suspect that the ceilings are supported on the left and right and a load-bearing wall is needed in the middle. This load-bearing wall between living room/office, living room/hallway, and kitchen/utility room is not continuous, however. Also, it makes sense to integrate the lower bay window in such a way that no corner is created towards the office/living room wall. It is better solved in the one floor plan on the upper floor with the continuous wall between children’s room 1 and bedroom. However, that would not be above the load-bearing wall in the lower floor. I don’t know why you need so much space, but with the furnishings, I find the bedroom and living room somewhat oversized. Under certain circumstances, that can even appear lost. Do you have a household help? 210 m² also needs to be kept clean. If I could afford it, I would certainly build a few square meters larger, but 210 m² would for sure be too big for me. If the size remains as is, maybe two more considerations: - How about aging suitability? Design the floor plan so that a separate apartment can be created upstairs later. - Provided there really are or will be two children, I find a guest room missing in your floor plan.