Saving or building, which is more sensible?

But that wasn't the topic at all...

What counts is what remains net per year and not what is shown bottom right monthly. If a woman fails to calculate that.. maybe some tutoring regarding math/taxes would help

Sorry, that's nonsense. That might work for you, but not for the average person. You also don't have the net amount at the end of the year in your account, but the monthly salary. There are enough women who belong to tax class 5 "forcibly" (for stated reasons), who then have to manage the family on their meager salary, while Otto with tax class 3 pays for the house, etc. In the end, the woman ends up with nothing, Otto with the status of the paid-off house. I am aware that you and your wife do not see yourselves in this story.

But this is already off-topic, so I'll leave it here... somehow too much trolling in the question.

Since the word Frugalism was mentioned here: The idea is to be satisfied with little and to achieve financial independence early in life through the savings rate.

The purpose of this is freedom, not fear. Anyone who is now afraid because of this lifestyle has not created freedom, but a cage.

I see an extremely deep-rooted problem here when what is supposed to make one free, on the contrary, puts one in shackles.

Regarding the topic, my advice, also for the reasons mentioned above, is that the OP should not build at the moment.

Simply put both into the IV and no one will be disadvantaged

Thank you for your helpful contribution that hits the mark very well, as well as your knowledge about frugalism. My goal here is not to become financially free but to have as much equity as possible for building a house by the age of 30. And I am putting everything into that, possibly too stubbornly. And I am aware that it will be very hard to get off the saving trip again when the time comes.

Let me summarize for myself. Building now is not good. So wait until I am 30, possibly earlier if the market relaxes. Am I seeing that correctly?

Purely technically, I consider €2000 net to be too little to repay a large loan healthily. And you want to manage it alone. And there are fixed costs that you cannot reduce through frugality. See other posts.

Other families build houses with two incomes EACH as large (or larger).

I personally also do not think it is wise to want to do it alone... even though I understand the desire behind it.