New construction costs - Is the financing in order? Experiences?

Says the one who is already looking for the next plot again ;)
You move into a detached house to have some distance and space. I find 430sqm pretty tight for a detached house, you also have to use the plot efficiently.

I am not looking for the next plot. The plot practically fell into my lap.

It would have been almost 1000sqm, but only 11m wide.. 3m setback from the boundary and that leaves only 8m in width.. So, as with many things, not everything can be defined by size...

And that is exactly the point, using the plot efficiently. Whoever sees our house and plot wouldn't believe it's "only" 390sqm. We have used it very efficiently from our perspective.

The same nonsense with the liquidation of a lucrative stock portfolio. Here, 5-8% returns over several years are easily given up to get 0.2% better interest rates at the bank...

Well, at some point, money and income are simply finite. We also liquidated part of our portfolio. It was much less about getting 0.x% less interest and more about having money that we don’t have to borrow, which noticeably lowered our installment and thus our monthly burden. Ultimately, if the annuity remains the same, borrowing 10% less also means 10% less installment. With the financing recently discussed here in the forum, that often means 200-250 euros less per month. Now one could of course say, "you could have kept the higher installment (as long as the bank agrees) and if push comes to shove, THEN you could tap into your capital stock," but if I almost expect that to be the case (because of, for example, planned children or similar), that wouldn’t be a really responsible way to handle money for me. Ultimately, it’s also simply a very high liability. In itself, this tied up relatively freely available capital that generated higher returns, fairly rigidly with losses in returns. But I have thus reduced monthly liabilities and bought myself free cash flow again.

Well, at some point money and income also run out. We also liquidated part of our portfolio.

As is often the case, liquidity wins over asset positions. You learn that very early in business administration, that nothing works without liquidity. So : Well done

In this sense, it means tied-up assets that cannot be converted into cash within a few days. Real estate, production machines, etc. It is completely correct: A company that on paper has assets of 20 million EUR, of course, does not have the money lying around liquid. To have the money, you would have to sell the company, but then it can no longer produce. A stock portfolio does not fall under this, because you can liquidate it within a few hours if necessary and transfer the money to your account. Provided the stock portfolio does not lose value dramatically upon sale, because, for example, you hold 20% of your own company, like Elon Musk. But that probably is not the case here... Therefore... just throwing in "You learn that in BWL 101"... unfortunately did not work here, because it is not correct like that ;)

Ultimately, it is also simply a very high liability. In itself, I thereby have relatively freely available capital, which brought a higher return, rigidly tied up with loss of returns. But I have reduced monthly liabilities and thus bought myself free cash flow again.

The deal isn't that bad. With higher equity, you not only buy that one-tenth off the interest rate. You also save the interest on that money, and with current interest rates, that's not a bad deal. 4% tax-free is about 5.3% before taxes, and that is guaranteed. Compared to the "5-8% returns" from #48, that definitely holds up. Especially considering that the stock markets are still fairly highly valued and therefore the expected return will likely be below the long-term average.

A stock portfolio does not fall under this, because you can dissolve it in a few hours if necessary and transfer the money to your account.

However, at the time you need it, it cannot be valuated in terms of worth today. Your tip to keep the portfolio causes genuine enthusiasm among many who needed money in 2003/2004 or 2008/2009 or at the end of 2011.
Otherwise, the guaranteed return through saved interest is also really valuable today. Above all guaranteed and not just temporary paper gains ==> see