Feasibility Single-family house + land 400,000 €

no, all good, they also build houses with roofs. But it is and remains a low-price segment. If you are already calculating tightly and cannot build up reserves, how should it be if something happens during construction? Were the T&Cs accommodating for you or did everything go smoothly?

Most things went smoothly. Where it didn’t go smoothly, it was corrected without any discussions (part of it is still pending because it couldn’t be done in winter now... but it’s only cosmetic).

How was the pricing with you at Town & Country? What was the biggest cost factor that added to the "excellent" price? Because turnkey for 186k can’t be right.

oh sorry... I completely overlooked your questions. The biggest factor was, I believe, the change in the heating concept. So instead of gas + solar, then an air-to-water heat pump (and underfloor heating). For the house including pattern modifications and changes (among other things, an extension of 4x5m as a basement replacement and a balcony above) we ended up at about 260k for approximately 150 sqm living space + the aforementioned room. Then there were various additional costs, some exterior work, kitchen, and the land. Roughly an additional 100k in total, more precisely I have to check soon.

oh sorry... I completely missed your questions.
The biggest point was, I think, the change in the heating concept. So instead of gas+solar, then air-water heat pump (and underfloor heating).
For the house including layout adjustments and changes (among others an extension of 4x5m as a cellar replacement and a balcony on top) we were then at about 260k for about 150sqm living space + the aforementioned room. Then there were various additional costs, a bit of exterior landscaping, kitchen and the plot. Roughly 100k additionally in total should be it... I’ll have to check more precisely soon

Thanks already for the info. I had a longer conversation yesterday with Town & Country, we would come out at about 210k for the house with 125sqm. What is the advantage of an air-water heat pump compared to gas+solar? That would be interesting to know. We might get a plot for just under 100k, which is significantly less than I had calculated. If that works out, we will definitely build. Although small and standard, it’s better than living in rent for a lifetime.

Then take 100k more. Then you have security and a buffer. If there's anything left over, you can put it into the [Sondertilgung].

Something else has come up in the meantime. We have a semi-detached house in prospect. The two semi-detached houses will be built on a 500sqm plot. The planning costs are 260k including a 130 sqm house, driveway, entrance platform, parking space, and carport (planning by the architect; somewhat higher estimated). The land costs are 52k (including additional costs), I estimate additional construction costs at 40k, although I am not sure how these behave with a semi-detached house (possibly cheaper?). Certainly, this is a relatively small plot, but it is enough for us. I have not overlooked the house that still needs to be furnished. We are taking the furniture completely from the current place with us; even the kitchen can be moved (around 1k necessary for additions). The floor and wall coverings, lamps, and other "small stuff" that will still arise, I think, are still within the 400k budget. Your opinions?

The planning costs are 260k including a 130 sqm house, driveway, entrance platform, parking space, and carport

Calculate a bit more – this price of 260,000€ is a base price. If you add 40,000€ more for equipment and technology, you reach your max of 400,000€. For what: storage size, heating, roller shutters, larger windows, bathroom platforms, built-in cupboards, outside water tap, rainwater, shed, ...