Financing single-family house in southern Lower Saxony - SPK on strike!

You can google that or find a shorter version on the Schufa pages. Each industry has its own score. However, I don't think there are huge differences. But it could be that you have a good to very good score for mobile phone contracts and car loans, but not yet a good one for a construction loan if you haven't had one before. That would be plausible, even though I consider Schufa overall too powerful and would be in favor of limiting its influence.

Hmm, thanks for the hint, I have to take a look out of interest sometime. I nevertheless just took a look at my own score, which has also jumped up within the last six months (Baukredit). At least it is now higher than ever before. Ha ha :)

Self-builders are probably statistically very reliable in payments.

I was once told that few scrutinize you more than banks that give you a mortgage loan. So if a bank does that and you also pay the installments properly, that is a much more reliable sign for [Schufa] than if you remain a blank slate. Sounds logical.

Sounds logical.

At an acquaintance of mine a few years ago:
At his own request, no overdraft facility, no financing or financing inquiries, no consumer loans, no credit cards. Not because he wouldn't have received any of these, but simply because he saw no need.
When he then wanted to finance a property, his Schufa score was poor because the above-mentioned aspects were not considered solid financial management but rather a lack of creditworthiness. "The house bank must have its reasons for not granting an overdraft."

Money wants to go to money is probably only dependent on the amount, not on the sign...