Building a single-family house with a basement - Is the financing calculation too risky?

You should not be intimidated by the average person. You earn and spend amounts that are unfamiliar to the majority of Germans and also to most users here in the forum. That causes fear. But it has nothing to do with you. It’s just a projection. The project is calculated soundly. Do it.

I expressed it a bit sharply. I understand your insecurity, which seems more feigned to me (sorry, I just can’t believe it with these numbers). Most here don’t come close to such a salary. Nevertheless, they have nicely justified a loan of 450-500k... if you’re missing 50k later, so what?! If necessary, there’s a loan with a rate of 300€. That won’t ruin you either.

If you have support in the worst case and would also accept it, so what.

Be sure to check the ancillary construction costs.
The basement is too cheap for including earthworks and everything. Equip the living spaces properly with electrical installations right away. Hope the granny flat does not have the south or west side.

Google this here. R.Hotzenplotz posted an offer for the outdoor area in '18. I think that could be in your direction. 11 euros for concrete paving, steel mesh, and cheap wall do not fit.
The 100,000 was not enough there.

I was a bit blunt. I understand your, to me rather fake (sorry, I just can’t believe it given these numbers) insecurity. Most here don’t have anything close to such a salary. Nevertheless, they have nicely calculated a loan of 450-500k... if you’re missing 50k later, so what?! Then you can get a loan with a rate of 300€ if necessary. That won’t ruin you either.

The ‘worry’ is simply not wanting to change our standard of living much, I just know many who then only argue etc. And 20 years is a long time in which a lot can happen. I’m just the 1000% type. It may seem strange to some.

The 'concern' is simply not wanting to significantly change our standard of living, I just know many who then only argue etc. And 20 years is a long time, a lot can happen. I'm just the 1000% type. It may seem strange to some.

I find that way of thinking quite realistic. Usually here in the forum, a lot of money was spent before building the house because it was in abundance, and then they say here that they are aware they have to tighten their belts, which is rarely credible. Small tip: teach the kids to save by having them save themselves the driving license cost, not by you saving it for them.

I find the thinking quite realistic. Usually here in the forum, people have spent a lot of money before building the house because it was abundant, and then they say here that they are aware they have to tighten their belts, which is rarely understandable. A little tip: teach children to save by having them save for their own driver's license and not by saving for them

Well, I was also relatively spoiled by my parents until I earned my own money (i.e., after my training); until then, I got a driver's license and an older car, and I want to do the same... on the condition that the children follow their own path and don't quit everything, etc. I have never had any debts before... only now for the house then...

I find the mindset quite realistic. Usually here in the forum, a lot of money was spent before building the house because there was an abundance of it, and then they say here that they are aware of having to tighten their belts, which is rarely comprehensible. A little tip: teach children to save by having them skip getting their driver's license themselves and not by saving for them

Do I understand this correctly? You are now spending €3k on living expenses without rent? So later there will be an additional €1.6k installment and €400 utilities? I also find it hard to imagine that someone who used to live well becomes a saver just because of the single-family house. That is rather unusual.