Floor plan, not a specific single-family house, approximately 200m² with 2 apartments

When it comes to planning separability in a forward-thinking way, keeping a dead-end staircase never even crossed my mind, so I didn’t understand that at all. For me, that would rather be in the realm of a last resort because the separabilities were specifically NOT planned for… If I plan it in a forward-looking way, I would simply plan the staircase in its own room or at least plan it so that it can be easily separated into its own room. Obviously, that doesn’t fit in the current plan at all, so you’d be back to square one (which might not be a bad thing…). In the Flair it could be done either by relocating the kitchen door or just leaving it there for now and then closing it when you want to separate. There’s still access to the kitchen through the living room.

What advantage other than the appearance (less cramped) would there be if the hallway became larger there and the kitchen smaller instead?

Well, for example, the door from the hallway to the large room could be moved slightly upward. That would allow you to put an office down at the bottom left and either you might even have the option to add a second door from the hallway or you could make the office door accessible from the living room, but completely without the stub. Otherwise, I still don’t like the kitchen layout one bit as it is. That means, at that spot I don’t like the hallway or the kitchen. I would probably even like the kitchen better if it just continued straight and didn’t go around the utility room (so simply a rectangle. Possibly also extending over the utility room but not as far as currently) and then put a door on the short side. Then you can fill the right wall entirely with cabinets. Or you leave the wraparound around the utility room but then I would still move the door and place a cabinet where it currently is or something like that. Either way, the variant with the combination of “hallway too narrow,” “kitchen with odd shape AND passage completely parallel to the hallway right next to it” simply seems wrong to me. It has to be better ;) Otherwise, you currently even have a cabinet drawn in the 120 cm (structural dimension) section once. That then probably doesn’t just look narrow but really also is narrow in practical terms.

In my opinion, the area at the top would also benefit from a larger hallway. Much smaller dressing room, but remove two of the four doors. A slightly longer bathroom and directly accessible from the hallway. Other doors, if possible, out of the corners. Or something like that. You don’t really need an office, you could use the space for a second small bathroom, for example (either with access from the dressing room as a master bath or from the hallway as a second bathroom for whoever). That would be adjacent to the other bathroom and both are roughly above the utility room, so for plumbing and stuff. Or you shuffle the rooms completely anew, who knows :) But as I said, I’m not a floor plan person, I only move walls around based on your basis, with all the limitations that come with it. Someone who can do that would take your room program and maybe come up with a completely different arrangement.

I’m not fixated on my execution, I just want to explain my thought process for why I decided this way in advance.

That simply came across differently on the other side than “no, this is all totally great, I have thought this through completely.” And then there were partly overly detailed explanations as to why things are the way they are, which sometimes seemed a bit absurd. (The bedroom story for example… without meaning to offend you, but a sliding door that you pull over the bed at mattress height to split it into two parts really seems a bit unrealistic…). The forum is somewhat rough, but ultimately most people cared that the plan is not a good basis. Then, as I said, the impression came across that you found it totally great and wouldn’t want a new plan from scratch at all.

Sorry, you really don’t understand ANYTHING. A partition wall is of course only installed once the house is divided. Your strange sliding door with staircase in the middle of apartment 1 is not a serious attempt at separating the apartment. Who would even rent that?

It really makes no sense here at all, you have inhaled your design and are in no way willing to learn. Have fun.

Ever thought that the house could already be divided and rented out beforehand and only become one house when the two children (or one) arrive? It’s about keeping different eventualities in mind. I seriously doubt that there would be no interested parties here at all. And even if that were really the case, I wouldn’t have lost more than if I planned anyway without a possible division. Besides the floor plan, the location or the site of the property is even more decisive for how desirable such an apartment would be—and of course also the rental price.

And you stamped the design from the start as failed (see eye cancer) because it was probably not drawn with DIY or similar, and you are looking for mistakes everywhere.

When it comes to foresighted separability planning, keeping a dead staircase never even occurred to me, that's why I didn't understand it at all. For me, that would rather be in the area of an emergency solution because the separabilities were precisely NOT planned..... If I plan it with foresight, I would simply plan the staircase in its own room or at least plan it to be easily separable into its own room. It obviously doesn't fit the current plan at all, so you'd be back to zero (which might not be wrong either...). In the Flair, this could be done by moving the kitchen door or just leaving it there at first and then closing it when you want to separate. Access to the kitchen via the living room would still remain.

Yes, the staircase would then be practically dead, but it would only be about 5m² and you might also be able to store things there. Someone here (or was that even you?) suggested "Haas sustainable adaptation options" for orientation, where the staircase is directly next to the apartment door separated off, but I don't like it here if you have to make a perceived world trip from the living room to get to the bedroom. In the Flair you can build a wall with an entrance door directly behind the front door and additionally at the top of the stairs. Once this is in place, it would probably be permanent, and moving furniture would be difficult.

Well, for example, the door from the hallway into the large room could be shifted a bit upwards. That way you could place an office at the bottom left of the plan and either you even have the option to put a second door from the hallway there or you make the office door from the living room but completely without the stub.

I haven't understood it 100%, but roughly. I have already marked a possible bedroom in the living room. In your case, this would then be the office but without the corner. To get into the living room, however, you would then have to move the load-bearing wall further upwards, which would on the one hand eliminate the entire kitchen wall and on the upper floor the axis of the walls also runs exactly above the load-bearing wall. If this were shifted further upwards, both doors to the hallway would no longer fit. The statics here are only my guess, and a structural engineer would have to look everything over first anyway.

Otherwise, I simply still don't like the kitchen layout at all. That means, at that spot, I don't like either the hallway or the kitchen. I would probably even find the kitchen better if it just went straight on and did not go around the utility room (so just a rectangle. For my part, it could protrude over the utility room but not as far as straight) and then make a door on the short side. Then you can at least completely fill the right side wall with cabinets. Or you keep the wrap-around of the utility room but would still move the door and put a cabinet where the door is now or something like that. Either way, the combo "hallway too narrow" "kitchen with a weird shape AND a passage completely parallel to the hallway right next to it" just seems wrong to me. It has to be better ;) Also, you have even drawn a cabinet in the 120cm (shell construction dimension) part. That probably won't just be visually narrow but also practically.

In my previous draft, I had extended the utility room down to the same height as the kitchen wall, but here that space seemed lost to me because it was just a passage (garage door was also positioned lower). So I thought that when entering the house, I wouldn't come straight into a narrow hallway, I can place the wardrobe directly next to the door and the kitchen cabinet on the bottom wall can be wider. Also, the door can be easily opened into the kitchen. I fully understand the criticism; most people feel most comfortable with a large open area with little compartmentalization, which is why you mostly see open kitchens nowadays. I basically like that too, which is why I chose such a large living-dining room. But I see the hallway itself purely as a "utility object." I only stay there to get from A to B. For the kitchen, I also thought a lot about whether it makes sense to make it wider or have an open kitchen with an island. This partly also involves aesthetics besides usability.
The "cabinet" in the 1.2m hallway is just a very narrow and deep chest of drawers; it is not fixed and was only sketched in as a potential option. In an improved design, I would also mark the heights in the floor plan. I personally see the whole house as 3D drawings, so I forgot to make such things visible in the floor plan.

In my opinion, the upper area would also benefit from a larger hallway. Walk-in closet significantly smaller, but remove two of the four doors. Bathroom a bit longer and directly accessible from the hallway. Other doors moved out of the corners if possible. Or something like that. You don't need a separate office, the space could also be used, for example, for a second small bathroom. (Either with access from the walk-in closet as a master bathroom or from the hallway as whoever's second bathroom). That would be adjacent to the other bathroom and both roughly above the utility room, because of piping and such. Or you shuffle rooms completely, who knows :) But as I said, I'm not a floor plan person, I just shift walls based on your basis with all the limitations that come with that. Someone who knows how would take your room program and a completely different arrangement might come out.

When planning my floor plan, I tried to use as little hallway (and stairs) as possible because I don't see much added value there. I am probably a bit burned here because I grew up in a house where the hallway stretched all the way from the front door to the garden door with widenings, and rooms arranged on both sides. The hallway swallowed so much space without people really staying there longer.
I don't necessarily see another full bathroom right next to the other one as sensible, especially since there is already an additional bathroom directly down by the stairs. If anything, you would rather try to make the children's rooms a bit bigger.

That came across differently on the other side than "no, this is totally great, I've fully thought it through." Then there were partly detail-loving explanations as to why things are the way they are, which sometimes seemed a bit absurd. (The bedroom story, for example... without wanting to imply anything bad, but a sliding door you pull over the bed at mattress height to divide it into two parts really seems a bit unrealistic...). The forum is a bit rough, but ultimately most wanted to say that the plan is not a good basis. Then, as I said, there was the impression that you already find it totally great and wouldn't want a new plan from scratch at all.

I have indeed put a lot of thought into many things here, and as I said, this is version 12 of my thought experiments. I am aware that small changes could have a domino effect. Therefore, I weigh how sensible the changes are. And here, in some cases, I would have wished for arguments instead of just saying this and that is bad. My main goal is to see what makes architectural sense and what doesn't; many things are a matter of preference. One person needs a 15m² bathroom, another is fine with half that size. For such things, I don't necessarily see a right or wrong. I am open to the Flair proposal, as I said, but many changes would still be required and I would need to deal more intensively with how feasible these are.
It is not really understandable to me how someone can get hung up on a gimmick (as I explicitly called it myself), especially since it has absolutely no influence on the rest of the floor plan. I definitely mean that applies to the separating door, but many things that were previously dismissed as unrealistic ended up being more innovative. As I said, one would probably have been torn apart by all the planners here if one had presented a plan with an open kitchen. You don't have to like such thought experiments, but you also shouldn't try to label the person as "stupid" or "childish."

I drew my floor plan with another architect's drawing program and made a few changes.