Project house construction. What can I finance?

So I think with your plan and the loan amount you need, it won't work in the current situation with only one income of that amount plus soon a household of three. I also can't imagine that the banks will go along, even if you list your condominium as capital?! Maybe it would really be worth considering to first think about dividing your property in order to get more available equity?

I have already consulted with Dr. Klein regarding financing with the apartment sale, i.e. 350,000 as a loan with 150,000€ equity. According to them, that is no problem. Much different financings get approved there...

Completely different financings are involved there...

However, their problems also affect the respective borrower.

In my opinion, it is not about whether the financing goes through, but about whether and how you then cope with it.

In the long run, (d)one salary certainly suffices for the normal expenses with 2 adults + 2 children + pets, but not to build reserves and possibly cover rental losses or maintenance/repairs. That was also one of the main reasons why we decided to sell. And we have double income and only 1 child.

Especially if you would preferably like to keep the property completely, I personally would not hold on to the apartment.

Their problems also affect the respective borrower.

In my opinion, it is not about whether the financing goes through, but about whether and how you then cope with it.

In the long run, an income is certainly enough for the normal expenses with 2 adults + 2 children + pets, but not to build reserves and possibly cover rent losses or maintenance/repairs. That was also one of the main reasons why we decided to sell. And we have double income and only 1 child.

Especially if you would prefer to keep the plot completely, I personally would not hold on to the apartment.

No no, that is already clear to me by now. Nevertheless, I also read here that it would not be feasible even with the sale of the apartment. That surprised me quite a bit...

Nevertheless, I also read here that it would not be feasible even with selling the apartment.

I didn't read it that way. Although here and there some people really consider every single cent.

Sell the apartment, use equity, keep the repayment a bit lower as long as your wife doesn't have any income, and when the income increases, then increase the repayment. That's how I would do it.

As for the costs, some things do not appear or are not fully included in the contractor's calculations. I wouldn't miscalculate it, but rather just call it taking a closer look.

At the beginning, we also planned amount X, meanwhile we had to add about 15% :)

We already have a cheaper prefabricated house provider in mind with Akost GmbH. At the moment, we are at around 2000€/sqm in an initial calculation. It will certainly increase, but rather not up to 2500€/sqm. We just want to keep the large plot of land. At least for now. Selling later is also an option if it just can't be done otherwise.

I would try to keep the apartment. Start with a low repayment and then increase it when the wife has an income. Also check if the rate for the apartment can be set lower.

If all else fails and it doesn't work, the apartment can still be sold. But you can only sell once.
And in the first years, it is not necessarily required to build a reserve for maintenance. That is sufficient in a few years as well.
Your wife still has over 30 years for a good income. You also have just under that.

And if the house no longer fits, you split the [Grundstück], then sell or rent the current one and build new again.