Floor plan design single-family house with around 150 m²

You have to have enough imagination yourself to push a bed against the wall if needed.

It is indeed standing by the (room dividing) wall. And when passing by the foot end, you then come quite close to the slope.

It is standing by the (Raumteil)wall. And passing by the foot end, you then come close to the slope above you.

: You must be kidding me - that can only be the case.

I somehow find these statements absurd. Which built-in wardrobe? I don’t see one in your draft. And if the tiny guest room gets even smaller, what exactly is that supposed to achieve? Please make a sketch showing what you gain from it.

It’s all so vague. My last information is the furnishing from #15. Did I miss something?

A built-in wardrobe was favored here by a forum member, who insisted that it absolutely has to be opposite the stairs in the hallway. But I think it has since been removed again. Do you really find the guest room so tiny? I mean, some children’s rooms are only 10-11 m² and the children live in them daily for years. I think if it is actually just a guest room or office, even 10 m² is more than enough. Upstairs, a room will surely be free before or after the children, so a larger guest or office room can go there. Therefore, I don’t see a problem if the room on the ground floor is only about 10 m².

You can do without a wardrobe cabinet and annoy yourself your whole life in this house because the clothes of three/four people cause disorder and collect dust under the open staircase.

Of course, you can also make the guest room, which is supposed to serve as a bedroom in an emergency, even smaller, but then nothing will be right anymore.
Where is it supposed to become smaller? Where is the wardrobe supposed to go?
You could also close off the stairs and underneath.... [emoji2]

I have sketched two ideas for the ground floor. I like the first variant better. In the corner on the left in the hallway there is even space for a wardrobe. Whether the additional wardrobe "in" the guest room is still needed can be considered. Maybe it can also be better accommodated.
By shifting the wall southwards around the fireplace, the hallway and the study gain area (shift of about 25 cm). The chimney/fireplace thus also does not protrude so much into the living room.
What do you think of these ideas?

What is that? [emoji33]
What are all those niches for?
The bricklayer will surely charge you extra corner fees...
What a waste of square meters.

If you move the stairs, the ground floor will correspond to the upper floor. Everything changes then.

As already asked above: how do you want to use the guest room as a bedroom if it becomes even smaller?
And you have to know yourself how many jackets and shoes each person has... there are few alternatives for storing seasonal clothing.
Distinguish between daily wardrobe and yearly wardrobe.
My husband and I have about 25 pairs (including functional and winter shoes) together.
If there are children too...
I would allocate at least 60 cm of closet width for outerwear per person.

Regarding the fireplace: I don't think you actually want to hide it in a niche? It wouldn’t stand out then at all?!

What is that? [emoji33]
What are all the niches for?
The mason will surely charge you corner surcharges for that...
What a waste of square meters.

There aren't that many niches. As I already wrote, I also prefer the other version...
And where are square meters wasted? Whether I have the wardrobe longish or rather square, it's the same in terms of square meters. Although you don't have to make such a square wardrobe niche here, you can also make it longer with less depth.

An upper floor belongs on top of a ground floor if you move the stairs. Everything will be different then.

Whether the stairway is in the right or left room upstairs shouldn't be such a problem. But sure, you would have to adjust it then.

As already asked above: how do you want to use the guest room as a bedroom if it becomes even smaller?

That would only be an emergency. I actually never want to use it as a bedroom. When that time comes, you'd adapt accordingly, no need for a huge room anymore...

And you have to know yourself how many jackets and shoes each person has... there are few alternatives where you leave seasonal clothes.
Distinguish between daily wardrobe and yearly wardrobe.
My husband and I have about 25 pairs (including functional and winter shoes) together.
And if there are children...
I would allow at least 60 cm of wardrobe width per person for outerwear.

I leave the seasonal wardrobe in the storage room upstairs (which somehow got lost in all these drafts, but it should definitely be there, opposite the stairs upstairs). It should have about 6-7 m²; several wardrobes for winter jackets will fit in there, as well as the vacuum cleaner etc.
In the ground floor only the current jackets and shoes should be there. In my draft, I have a large niche and a sideboard for that. Plus the space under the stairs. Honestly, that’s all you can have.

About the fireplace: I don’t think you actually want to hide it in a niche? It wouldn’t really stand out then?!

The fireplace will probably be double-sided and the glass will protrude in front of the chimney (about 40-50 cm). Even the chimney already sticks out of the niche (about 10-20 cm). Attached is a picture how it should roughly look (imagine it double-sided and protruding a bit more). I think it will stand out well.