New single-family house in southern Germany

Addition:
- As a temporary location for the carp for the feast
- as a cleaning place for large grill grates
- foot (nail) care
- ...

...and in case you happen to run over a giraffe on the way home and then have to prepare it for the grill. You can explain everything with everything.... You can always need everything.

So accommodating a child in about 12 sqm, I consider - let’s call it - bold.

Nonsense... 12 sqm is totally fine, of course it also depends on furnishing/design AND whether everything is fully occupied.... which brings us back to the topic o_O

a child grows

....usually more in height!

When the balcony is gone there will be a room with almost 20 sqm. That should definitely be enough

....compared to that an all-purpose room on the ground floor with 37 sqm??? Hm.....

I myself have never found a model house that I would have built exactly the same. Therefore, I would consistently look for a regional provider, where maybe I can have the utility room extension 4 sqm larger or something like that, and the costs wouldn’t explode just because I want a wall a bit further left or right. Here in the forum, a few have also built their houses with Scandinavians, which I found nice.... the houses.

Yes, it does. It's called a living room there. And since it's a semi-detached house, we even have 2 of them, one on the right and one on the left.
And no matter what you think about it, we won't take them down. We like those things.

First of all, it's not that high on our priority list.

Great! I'm not alone :) (Bathtub and bay window). Depending on the view (bay window), floor-to-ceiling windows might possibly be nicer. But the deal is sealed anyway :)

...and in case you once hit a giraffe on the way home and have to prepare it for the grill afterwards. You can always explain everything with everything.... A man can always use everything.

Ever heard of "irony"? :)

Nonsense... 12 sqm is absolutely okay, of course it also depends on furniture/design AND ...

I stick to my opinion. I find 12 sqm too little for a child. At the latest in adolescence – when the boyfriend/girlfriend will stay over – the wish for a 120 cm or 140 cm bed, a dressing table (imagine an equivalent for boys), and a seating area for other friends to chill will arise.

...
...usually more in height!
...

For most children, yes :) But demands grow with the "height"... see above! It doesn't have to be "living" like Harry Potter under the stairs :) The space availability was already clarified and expanded by the OP.

Super! I'm not alone :) Depending on the view, floor-to-ceiling windows might be nice(r).

No, the Schwibbögen will go in there next Christmas. (Now there will probably be some harsh comments.) The floor-to-ceiling windows = patio doors face the garden.

Does this then mean that nowadays almost only houses are built by people who simply want to "belong," since they forgo the basement?

Sort of. Houses (in general) are still mostly built today by people for whom this would also have been possible at other interest rates – but specifically, the target group of builders who can only build due to the current low interest rate environment is found both strongly disproportionately to dominantly in the "basement costs and architect fees are just stumbling blocks on the way to homeownership" discussions and also constitute the majority of demanders in the alternative villa market segment. Therefore, you perceive reality somewhat "distorted by development," and my explanation was specifically aimed at this perception. The people who, even in "peacetime financial markets," would have been able to build, according to my observations, have essentially an unchanged position regarding the basement issue, i.e., a north-south gradient with no basements on the coast and basements in the south as the rule. In this group, it is merely noticeable that, as already mentioned, the omission of the oil tank and the tendency toward dryers instead of clotheslines remove large parts of "traditional" basement areas from the calculations.

So accommodating a child in about 12 sqm seems – let me call it – daring to me. Please don’t forget: a child grows up.

On the contrary – please don’t forget that today’s youth generations tend not to flee the nest from the “hotel mom” – I would call it daring to hope that the kids will voluntarily move out when they get 21 sqm.

If you now want to implement adjustments and special requests, the general contractor (GC) would be your man. The fittings with the GC are often better,

Whereas here two comparison candidates are in play with Weberhaus and Town & Country, one of whom, as an employee house builder, pursues a concept in which standard upgrades are a well-liked source of revenue, while the other, as a worker house builder, rather follows the concept of "baking affordable sponge cakes and leaving the impressive cream cakes to the confectioners" – Weberhaus, in my opinion, serves basically the "Coppenrath faction" here, and only in the target group of "young families" do I see overlaps – i.e., only there are they competitors, but one should not forget their different orientations.

No, the Schwibbögen will go in there next Christmas after all. ...

I fully support you!

...
On the contrary - please don't forget that today's generations of young people do not tend to leave the "Hotel Mama" nest - I dare say, hoping that the brats will voluntarily move out when they grow up if they get 21 sqm.
...

So better a place under the stairs like Harry Potter after all?

The floor plans are very compact. Take all the floor plans and draw in the existing or desired furnishings to scale. Often, dollhouse furniture is drawn in to make it look more spacious.

Without a bathtub, I consider it risky. You don't know the preferences of roommate No. 3. Presumably, bathing is preferred.
Laundry in the bathroom is acceptable as a last resort for 2, but not for 3.

I like No. 3 best.