New construction - What is included in our financial budget?

My plan is that first a meeting with the bank will take place to see what would even be possible for us! We are fully aware that we cannot make big leaps. We would have to make some compromises on the house. But we are not demanding in that regard. What exactly fits within that scope belongs in a [Thread], not here. Our financial situation is healthy, we have no loans for a car, …. It is just the short term of, let's say, 23 years and the lack of equity (please do not ask again or speculate that nothing was saved and therefore one cannot handle money!!!) that makes the whole thing problematic! I have another question. Is it better to have a fixed loan rate for the entire period or, for example, for 10 years? I would then have to renegotiate, and who knows what will happen in 10 years!?

My plan is that first there will be a conversation with the bank to see what would even be possible for us!

Very good!

Our financial situation is healthy, we have no loans for cars, ….

That is also correct.

I have another question. Is it better to have a fixed loan rate for the entire time or, for example, for 10 years? Then I would have to renegotiate and who knows what will happen in 10 years!?

The question cannot be answered in general terms. It depends on your financing structure as well as your expectations for future interest rates.
But I can tell you that the pure 10-year fixed interest period is no longer taken that often. For a small surcharge, you can buy security – just right for Germans.

You answered your own question.

In times of historically low loan interest rates, one should secure the interest rate long-term, depending on intended special repayments and changes in the repayment rate.

I just spoke with the person responsible at Schwäbisch Hall. Since he had time, we briefly touched on it, but there is another appointment next week where it will be more detailed. According to the initial figures, he told me (which is of course not concrete) that with a 25-year fixed interest rate (about 2%) and €800 monthly, you would reach around €240,000. According to the first assessments, this would be a feasible financing. Here, 5% special repayment per year is possible, which would then reduce the amount. So the term would be shorter again. For example, the BKG could be flowed in here or a possible payout from the parents' house. Of course, this is all just briefly outlined, not usually done on the phone, but I know the gentleman a bit. Concrete details hopefully from me next week!

After the first figures, he told me (which of course is not concrete) that with 25 years at a fixed interest rate (around 2%) and 800€ monthly, you would get to about 240,000€.

Then you are not done after 25 years. You have a repayment of 2% - so approx. €70,000 remaining debt after 25 years. But for €240,000 you will not get the house + outdoor facilities etc. that you considered in your first post. For safety, do not include the BKG; that usually goes towards other things.

For T€ 240 you do not get the house + outdoor facilities etc. as intended in your first post.

What is this statement based on? Have I overlooked the construction plans, the contract for work, and the description of construction services anywhere?

Have there already been indications regarding the planned and intended own contributions?