Construction costs are currently skyrocketing

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

What do you need 180 sqm and more for? Then ask in the forum. You should find enough examples. And please ask about their usage concept at the age of 65 and older.

I have definitely seen quite a few floor plans like that here. There are hallways the size of apartments, cat rooms, home cinemas, and similar things planned. Or rooms are simply generously sized, for example 25 sqm kitchens in huge open-plan spaces. I can count on one hand the cases of a family with 5 children who actually need that space in my nearly 2 years here in the forum. For everyone else, as already said, it is simply luxury, not a real need. By the way, these uses are also relatively independent of age and children.

Especially if I had 5 children, I would need a small house of my own...

I know more people who have money and say "...the roof, we won't do that anymore either...." Because larger sums are rather invested in caravans and cruises.

On the other hand, many retirees let their houses fall into disrepair because their pension is not enough to maintain them.

I know more people who have money and say "...the roof, we won’t do that anymore either...." Because larger sums are rather spent on caravans and cruises.

One group of retirees cannot carry out extensive renovations, another part does not want to and spends the money on their own nice things. Everyone as they wish!

No one said that this forward-looking option is free of charge. And no one claimed that this option is easy to implement. But some users have already provided their examples of this way of thinking.

In particular, politics should think goal- and practice-oriented or act in the interest of the population. If these impractical "ideas" from the example remain only theories and/or can be put into practice by only a tiny fraction of the population, then it is misguided politics that only contributes to amusement and very quickly ends up in the "blabla drawer." The examples given by the users can be counted on one hand, whereby I assume and claim that they will certainly have their "aha experience" once the time comes to put the theory into practice.... In other words: having taken your own "preparatory measures" is nice, but whether these later prove to be correct and/or comply with all construction technical and legal requirements is probably another matter.