Construction costs are currently skyrocketing

On the other hand, many retirees let their houses fall into disrepair because the pension is not enough to maintain them. And because a house simply cannot go 30, 40, 50 years without renovation... so it’s actually not a bad idea to prepare to rent out part of the house... But unfortunately, it’s not financially without challenges, that’s true...

The problem here is the mentality regarding home ownership. Once someone builds, they want it to stay in the family, that he/she/they will be carried out "feet first," etc., etc. In other countries, people are much more pragmatic. There, houses are sold, bought, and exchanged. I also see the problem here with the additional costs (taxes, notary fees, etc.) – if we could finally get a handle on that, many of these problems wouldn't exist.

The problem here is the mentality regarding home ownership. Once someone builds, they want it to stay in the family, that he/she/it is carried out "feet first," etc., etc. In other countries, people are much more pragmatic. They sell, buy, exchange. I also see the problem here with the additional costs (taxes, notary fees, etc.) - if we could finally get those under control, we wouldn't have many of these problems.

Full agreement. What notaries earn may have been reasonable back when houses still cost 30 or 40% of today's prices. We were lucky; for time reasons, our notary scheduled double appointments for the land sale, with two buyers always sitting at the table simultaneously. Apparently, he was not allowed to charge the full 1.5% for that... A similar thing applies to the commitment interest rates of banks. That comes from times when mortgage interest rates were 5, 6, 7%, and the amounts were correspondingly smaller. PS: Nowadays, 0.25% per month, 3% per year, is completely absurd on amounts of 500,000 EUR and more. For real estate transfer tax, one would have to come up with a model where one is exempt from the tax when buying or selling a property for personal use to buy another property for personal use with it... But... and here we are back at the beginning... real estate transfer tax and property tax are two very important, direct sources of revenue for municipalities. Those without industry that pays substantial corporate taxes depend on it. The city of Baunatal (VW transmission production) can easily do without it... Frankfurt Oder probably rather not...

But it is not just a question of money, but in practice it is hardly possible to design a floor plan for both.

We have planned a single-family house with 220sqm of living space plus utility areas and prepared everything. In the adjacent offices, the installations for kitchen and bathroom are in the walls, and in the outer wall already the lintel for a front door. Everything is quite easily separable into its own dwelling unit. Likewise, the upper floor can be separated into a dwelling unit. And anyone who walks through here would never get the idea that this house could quickly be divided into three apartments... The additional costs were quite manageable. But we did not plan the super luxury solution for extra sound insulation, etc. The entire house is well soundproofed as it is.

On the other hand, many retirees let their houses fall into disrepair because the pension is not enough to maintain them. And because a house simply cannot go 30, 40, 50 years without renovation... so it is not a bad idea to prepare to rent out part of the house... But unfortunately not without financial effort either, that's true...

But we would pull the ripcord much earlier and sell. You often see these completely, but completely run-down dumps in the real estate markets. It doesn’t have to come to that. The buyer would sometimes have to tear down more than renovate.....

Anyone who doesn’t plan for a granny flat from the start doesn’t have to worry about it.... Nobody will pay for the remodeling costs alone anymore...

Yes, changing floor plans afterwards so that subdivision would be possible is not economical. I am currently seeing this with an inherited property. If it were remodeled like that, it would not be economical in any way.

But we would pull the emergency brake and sell much earlier. You often see these completely, but completely run-down huts on the real estate exchanges. It doesn't have to come to that. The buyer would, in some cases, be better off demolishing than renovating.....

And then? You imagine it to be easier in your early 40s than it actually is at the end in your mid-80s. You have lived in your house for 40, 50 years, know every floorboard by name. And then you simply sell, move into a small apartment and basically start over? I don't know anyone, neither in my family nor among acquaintances, who knows someone who has done that...

And then? You imagine it to be easier in your early 40s than it is in your mid 80s in the end. You have lived in your house for 40, 50 years, know every hallway by name. And then you just sell it, move into a small apartment and practically start over? I don't know anyone, neither in the family nor among acquaintances, who knows someone who has done that...

We have met quite a few who prefer to live in a condominium with full service and travel carefree around the world, rather than having to take care of a complete (vacant) house with garden in terms of cleaning, burglary protection, garden maintenance, and so on. We would do that immediately as soon as the children leave the house. But it’s definitely also a matter of mentality. Real estate does not get better over time. Who today still wants the 80s junk with yellow/brown/green bathrooms, 300 sqm living space, indoor pool (90% dried out because of huge costs or broken), old stucco ceilings etc. etc. etc.? Its half-life is long over. Better to sell early, get a good price and do something new. Or take over such a rundown property with a backlog of renovations. But as I said, it’s a matter of mentality. There are certainly people who defend their 200/300 sqm castle until their last breath :)

Then it just means continuing to live in 180 sqm or more with all the consequences or building new again... everyone knows in life that children eventually go their own way.

Counterquestion: why do you need 180 sqm? I grew up as one of five in 125 sqm and we are now building about 130 sqm for three people including 2 study rooms. Even though the layout upstairs is a bit compact and could certainly benefit from 20 sqm more, I absolutely see no reason to inflate the house by half again. Somewhere in our size range is the point where more space is not necessary but luxury. And yes, as a consequence, people will either build new or keep the old house. As long as moving costs 50k, many people will stay in the old house, even if they aren't really attached to it. You always somehow fill the space, even if it's just the guest rooms at Christmas and birthdays.