Construction costs are currently skyrocketing

Cryptocurrencies and stocks are just too volatile for many.

Dangerous half-knowledge, but wasn't there talk of a ban on crypto (or at least Bitcoin) in the EU?

You have to put this into perspective. Around 100,000 residential buildings are constructed per year. Only about a quarter of these are single-family houses.

hm, so destatis reports Of the approximately 256,000 completed apartments in 2019, 40% were built in single- and two-family houses. However, the trend has been declining in recent years... In 2019, around 14,400 apartment buildings with a total of about 143,000 apartments were completed. These apartments had an average living area of 78 square meters. Apartments in new single-family houses were almost twice as large recently: The living area in the approximately 83,800 completed single-family houses averaged 152 square meters. Detached single-family houses even offered their residents slightly more space with an average living area of 157 square meters. Interestingly, the square meter figures, which the forum considers to have tended to decrease: Although the number of newly built single-family houses has dropped significantly in recent years: 2019 saw less than half as many such houses completed as in 1999 (178,000). However, they offered on average around 14% more space than 20 years ago. So there are fewer builders – but they go all out. Or in other words: the "normal" builders with rather lower incomes are missing nowadays, while the high earners continue to happily build large and even larger...

Although the number of newly built single-family houses has decreased significantly in recent years: in 2019, not even half as many such houses were completed as in 1999 (178,000). However, on average, they offered about 14% more space than 20 years earlier.

Well, many built around 120 sqm for the family in the 1999s (my parents and many there as well).

The question is: How is that calculated? With or without basement?

If I now build without a basement (which many do for cost reasons), then I have 120 sqm * 14% = 16.8 sqm additionally. That is the utility room and possibly a guest toilet as "luxury".

hm so destatis has to report…

But it doesn’t say exactly how many single-family houses there are, since two-family houses are included. But it doesn’t matter, the basic statement remains the same. In the short term, there may be distortions, but overall it will be such that fewer people can afford it, yet prices won’t really fall. I’m repeating myself, the last 10 years were rather an exception with initially slowly rising real estate prices but rapidly falling interest rates. Edit: I didn’t see the second paragraph at first.

The question is: How is it calculated? With basement, without?

It says there: living area. This is usually specified for banks, building applications, etc. For basements, only if ceiling height, windows, emergency exits, etc. meet the requirements. This is rarely the case for the utility room in the basement, but it is in the ground floor. So it is added to the living area only if built on the slab. Things like children’s bathrooms, extra dressing rooms, and 16 m2 bathrooms with sauna were not so trendy back in 1999, but they do inflate the volume accordingly...

hm so destatis reports

Of the approximately 256,000 completed apartments in 2019, 40% were built in single- and two-family houses. However, the trend has been declining in recent years...
In 2019, around 14,400 apartment buildings with a total of about 143,000 apartments were completed. These apartments had an average living area of 78 square meters. Apartments in new single-family houses were nearly twice as large recently: The living area in the approximately 83,800 completed single-family houses averaged 152 square meters. Detached single-family houses even offered their residents a little more space with an average living area of 157 square meters.

By the way, the square meter numbers are also interesting, which according to the forum tend to decrease:

Although the number of newly built single-family houses decreased significantly in recent years: in 2019, less than half as many such houses were completed as in 1999 (178,000). However, on average they offered around 14% more space than 20 years earlier.[/U]

So there are fewer builders – but they are really going all out. Or in other words: the "normal" builders with rather lower incomes are missing these days, while the better earners continue to build large and even larger as always...

The trend that houses are being built larger than 20 years ago does not make sense to me. Back then, nearly all houses had a basement, today it is the minority.
Possibly there is 14% more above-ground area today, but the total living + usable area should be less than back then, since basements do not count as living space in this consideration.