Approx. 160-170 sqm Upper Bavaria. Liquidity planning, experiences

The costs are already immense, but I am not very enthusiastic due to the many negative reports about prefab houses and would rather build individually.

P.S. A prefab house has nothing to do with an off-the-shelf house. It only has to do with the construction method. A prefab house can be built as a solid structure or as a timber frame, and can be an off-the-shelf model home as well as completely individually designed by an architect. The same applies to the "normal" masonry house.

Thanks already for the feedback. Of course, I don't want to show off. That was a serious question. I understand that this is a good starting point, but I wanted to make sure that it is enough. Maybe I am also in the wrong thread. Otherwise, I don't have much to do with construction, and the comments already helped me that the 600k for the house will not be enough.

The neighboring half is also basemented but originally dates back to the 1960s. According to the architect, who carried out a similar project two houses down, "solid building substance." Unfortunately, what is currently available to us is simply much too small. In addition, the architect mentioned 4.5k/sqm. However, it seemed to us that he mainly takes care of upscale properties. The house in question is supposed to cost well over 1 million... But our needs are not that extravagant.

The neighboring half is also basemented,

That makes your construction very complex, as the neighboring house including the basement must be supported.

Besides, the architect mentioned 4.5k/sqm. But it seemed to us that he rather manages upscale properties.

At that price? Yes, that’s already luxury. Unless he included ALL costs and not just the 300/400 costs according to DIN 276.

Our needs are not that extravagant.

They don’t have to be extravagant in the sense of pretentious or over the top, but why shouldn’t you have sensible things or a certain level of comfort (not flashy) built in?
For example, I mention: maximum insulation, controlled residential ventilation, high-quality windows, air conditioning!, ecologically sensible building materials, nice parquet/floorboards, shading, beautiful patio roofing, attractive house facade, necessary built-in furniture...... I consider these things sensible or at least worth seriously thinking about and by no means pretentious.
In this respect, I regard the architect’s rule of thumb as rather serious; if you don’t take full advantage of it, so much the better..

In this respect, I consider the architect's rule of thumb to be rather reliable;

Yes, if you are actually operating in the luxury segment - these are (always referring to the pure construction costs) the prices I see with our clients in the luxury segment (condominiums from 12-15k per sqm).

Thanks already for the feedback. Of course, I don't want to show off. That was a serious question. I know that this is a good starting point, but I wanted to make sure that it's enough. (...)

In the end, you can quickly calculate that yourself, it doesn't have to be precise to the cent. You need a 750,000 EUR loan, no idea, 3.5%?

Net income should be, assuming a reasonable tax advisor, around 10,000 EUR/month? Let's just say 9,000. From that you take 40% for the installment, so 4,000 EUR or 3,600 EUR. That leaves 6,000 EUR or 5,400 net, which is still more than the average family has.

Then you would be done with the loan after 22 or 24 years, assuming interest rates don't significantly drop again.

And precisely because you can calculate this so easily... and it is more than obvious and more than solid enough... I sometimes don't understand how someone can seriously ask such a question.