Construction costs are currently skyrocketing

Realistically, the key interest rates should be at 6 percent and the mortgage rates at 8 percent. Everything else contradicts all economic principles.

Although I disagree with the rest of you, , the numbers could indeed move in that direction, even if it is only a gut feeling.

Much more important than the general interest rate level is the real interest rate. Unfortunately, many forget this! The real interest rate is currently massively negative. Therefore, I advise everyone in the current situation to finance, for example, the photovoltaic system immediately. 2.5% sounds like a lot, but if module and installation prices rise again by 10% p.a., it is actually -7.5%. With energy prices likely to rise in the medium term.

Much more important than the general interest rate level is the real interest rate. Unfortunately, many forget that! The real interest rate is currently massively negative. Therefore, I advise everyone in the current situation to, for example, co-finance the photovoltaic system right away. 2.5% sounds like a lot, but if module and installation prices rise again by 10% p.a., it is effectively -7.5%. With energy prices likely to rise in the medium term.

As of today also in Handelsblatt. A loan would still be worthwhile because of inflation.

As of today, also in Handelsblatt. Taking out a loan would still be worthwhile because of inflation.

That is correct. In my region, I have seen for about 4 weeks now that people either
a) partially likely stop their construction project (new build) (rising mortgage rates + material prices)
b) have difficulties selling their existing properties (rising interest rates, high energy prices)
both are logical and typical for the market.

If interest rates rise, the property price falls due to decreasing yields.

But all of this is highly speculative in the current market environment!

Our local banks (e.g., [die Sparkasse]) now all have an interest rate of 3,x % for 20-25 year [SZB]. That's almost 2% more than in January.

b) Difficulties in selling their existing properties (rising interest rates, high energy prices)

Don't forget that renovation is also becoming significantly more difficult right now. Simply replacing the oil burner with gas and having peace of mind for 10 years is no longer an option.

Let's put it this way, the key interest rate is already at 0.0%: it can't go any lower (otherwise you would get paid for your loan!)

Look at Switzerland, it is at -0.75%. But the key interest rate is irrelevant for real estate financing since it is at the very short end of the yield curve. More important is the middle section with 10, 15, 20 years.