Buy a single-family house - mortgage a condominium unit and sell it later?

Yes, of course. The OP says that he wants to be done with the €300k by retirement and that they cost him €1,500. For the additional €400k (which he necessarily needs if he keeps the apartment), he also has to pay properly. And over 40 years term it will be difficult, so a bit more than 1% repayment is necessary (I calculated with 1.5% interest and 2% repayment). For that, he has no debts on the apartment.

Rented apartments must be affordable. They are not always a sure thing, but need to be carefully calculated.

OK, I hadn’t made that mental step. In that case, I am of course completely with you.

There is only a or b. A: Sell the apartment now with the right of residence until the house is completed (more risk) B: Bridge the apartment sale with interim financing, but higher financing costs and more security

What risk do you see with A? The right of residence expires, but it is not finished yet? Anything else?

What risk do you see with A? The right of residence expires, but it's not finished yet? Anything else?

Problems with construction, insolvency of the contractor, botched work.... unfortunately, there are quite a few, even if only very minor.

Problems during construction, insolvency of the contractor, botched work.... unfortunately there are quite a few, even if only very few.

Ok, so primarily the risk that something goes wrong with the new property and not the residential right itself. Construction is underway for us now and we are currently considering when is the best time to sell the condominium. It will surely also come down to a residential right, hence my question.

Problems during construction, insolvency of the contractor, shoddy workmanship.... unfortunately, there are quite a few, even if only very few.

Yes, I’m afraid of that too. I’d rather finance a bit more for 1-1.5 years on a variable basis and only sell my condominium once the new place is ready. I want to spare myself the stress. Maybe I can even sell the apartment a year later for a slightly higher price, then the additional interest pays off. I would have only sold an apartment before construction if I had gotten a bargain price for it.

Yes, I am afraid of that too. I prefer to finance a bit more variably for 1-1.5 years and only sell my condominium once the new place is ready.
I want to spare myself the stress. Maybe I can even sell the apartment a year later for a slightly higher price, then the additional interest will amortize.

I would only have sold an apartment before construction if I had gotten a bargain price for it.

And that is exactly the case right now. In my opinion, we are currently in the era of “bargain prices.” Due to the recent interest rate increase, those looking for property are trying to buy at all costs. However, in my view, this hype will taper off somewhat in the coming months, especially if interest rates continue to rise slowly. But that is just my opinion. We will probably take the full risk, sell now, and use the equity for the new financing. If everything really goes wrong, then we likely have miscalculated. Unfortunately, no one has a crystal ball.