New single-family house construction - How solid is the financing?

Mh... I don’t see things as rosy as everyone else.
I had the impression that most banks do NOT accept parental allowance as sustainable income.
That would rule out most banks, since an income of €3200 is simply not enough for the required financing amount.
If the woman works again, it is mathematically feasible.
Then the question is whether you want to finance half a million with an income of €5000. For ME that would be too tight. However, I don’t find expenses of €3000 for a family generous either; we need more even though I consider myself frugal.
The loan-to-value ratio is also not good, so the interest rates are not optimal either.
Are there parents/in-laws who can contribute equity or could help out in case of emergency?
Without a safety net at all, it would be too tight for me, especially with regard to the desire for more children, which is simply an incalculable factor.

Finally someone who ends my high-flying thoughts - good! ;-)
So if parental allowance isn’t counted as fixed income, of course it doesn’t work out at all.
I haven’t heard that before - but let’s see what experiences I gather about this.

But I do agree with you, when I think of €500k, I really get dizzy! Dealing with such amounts privately is, let’s say, an adjustment.

Looking at the monthly burden, I have a “somewhat” better feeling.
As of now, the three of us get by comfortably with €3000 per month. In most months, our expenses are between €2200 and €2500 (with €500 cold rent).
Another point is the “special payments” like vacation pay, Christmas bonus, and profit sharing.
The debt service must be covered without these add-ons, but those still amount to another €8-9k (net) per year - which at least provides a small sense of security.

But good input, you need that from time to time, thanks!

Furthermore, there have already been several posts about ancillary construction costs.
I have to go into detail myself and also have an intensive talk with the general contractor about it again.

Otherwise, somehow a crazy furniture/kitchen discussion has been sparked here.
Also interesting, I was able to read a bit more “between the lines” for myself.

As always: Many thanks to everyone :)

But I do agree with you, when I think of the 500k, I really get dizzy! Operating privately in such spheres is, let's say, an adjustment.

We felt the same way. Don't worry, that's normal when building and you get used to spending money with both hands.

In the past, you would spend weeks or months deciding which small car to get and comparing countless models.

Today you get the info, by the way, we need to order the bricks now. Please decide within the next 3 days by the weekend. – Oh, you want these? That’s 5000€ more.

So in the worst case, you end up with a few small cars. That’s why my tip is to have a generous buffer. At our savings bank, we could return unused buffer funds.

Furthermore, there have already been several posts about the ancillary building costs. I myself need to go into more detail and also discuss intensively with the general contractor.

Highlight everything in the scope of services description of the general contractor that mentions anything about "provided by the client" or "owner." Then get a second or third opinion, for example from friends who are also building right now, and ask what they spent on such positions.

The small car is a poor comparison because it depreciates in value.
With the house, the 500k is not just an amount without any equivalent value. Especially with more equity invested, one has more assets than debts.
What is simply important is whether one can reliably service the debt monthly and still have the possibility of a further life.

I had the impression that most banks do NOT accept parental allowance as sustainable income.

That was no problem in our case, however, we had to confirm in writing that Mrs. would start working again from date x and then earn amount y. As a civil servant, there were at least no discussions.

So if the parental allowance is not counted as fixed income, of course none of this works out.

Applies if parental leave exists during the inquiry/signing of the financing.
Since you write that she is initially returning to "full" work for 25 hours again, you should apply for the financing during this time as well. Then you will be at 4800€ (without child benefit).

Furthermore, there have already been several posts about the ancillary construction costs.
I myself need to go into detail again and also discuss intensively with the general contractor.

Working out details and costs yourself makes a big real difference compared to what the general contractor states. It is often more than double... The general contractor wants to sell, not deter.

Regarding "vollerschlossenes Grundstück" you should inform yourself again. I also bought one like that. In Hessen, a property is considered fully developed if the connection lines are reachable within a radius of 150m(!!). That means, in the worst case, you have 150m of civil engineering work. I probably don't need to explain to you what that costs :(