Is our new building realistically financeable?

But whether you want to pay €2500 monthly for the installment plus additional costs, of course only you can decide.

That is exactly the crux of the matter: €2900 per month just because you want a single-family house is not everyone's thing. It's not about working more to afford it, but simply being willing to spend that much money every month.

If you already had the initial consultation: what monthly rate did the bank offer you?

I'd be interested too. Probably, some nonsense rate came out with 2% repayment :-)

, zaba12 - we have projected various bank installments of 1800-2300 monthly, but the remaining debt in 10/15 years was quite high and that still needs to be optimized, and we will probably end up with the amounts you provided. Honestly, that's too much for me, but I don't know if everyone does it that way and if it's a completely normal area (40%).

I don't understand that either. The purchase price corresponds to almost 60 years' worth of rent

That's why I asked if a family lives in it, because the rent is indeed so cheap.

, zaba12 - we have various bank installments. 1800-2300 monthly was projected, but the residual debt in 10/15 years was quite high and that still needs to be optimized and we will probably end up with the amounts you gave.
Honestly, that's too much for me but I don't know if everyone does it that way and if it's a completely normal range (40%).

There is hardly anything to optimize here. The total sum is simply too high without equity - either increase equity to six figures and reduce installments and interest or just afford the mentioned installments. In retirement, you can't service such an installment/residual debt and the bank won't care in 20 years whether you can manage it or not, because they will get their money anyway in case of a sale.

and moHouse :)
It is not rented within the family. Yes, I understand that the rent - apartment price ratio might not sound quite proportional, but the idea behind the purchase was different - Plan B in case we unexpectedly had to return home or something like that, so that we already have something paid off. In the meantime, it is rented out until we have personal use needs. This is the local customary rent but with a 5% increase in rent each year.

[*]Total income approx. 85K net per year
[*]Total expenses approx. 55K
[*]Balance
[*]of which total cold rent and dispensable savings contributions (e.g., savings rate for house) 13,800 p.a.

30k surplus plus 13.8k cold rent makes 3,600€ per month as a theoretical upper limit.
From this perspective, a 2,500€ installment would also be no problem.

But whether the numbers really all add up and there are no hidden costs lurking somewhere like new cars, that must be checked very thoroughly. (By the way, this item is mentioned in the list but was not answered.)

Personally, I would go for it with these numbers.