> First please define what you mean by "last" so that we share the same semantics and then provide a source on this.

Le me just try to give a definition, "lasting" for me means that you only do maintenance and rework that you would still consider the building year to remain the same after you are finished.

Also the semantics of the term "lasting" were not the issue, the issue is that you do not my sources because you find the term economic lifetime and its definition unacceptable.

> Are you referring to https://www.bauprofessor.de/wirtschaftliche-nutzungsdauer-ge... ?

No I mean my number that approximately half of housing buildings are younger than 1977, so approximately 50 years.

This refers to a survey by the government, see box on bottom: https://www.bundesregierung.de/breg-de/themen/klimaschutz/kl...

Someone else in this thread posted a similar source from ourworldindata which has a bit older data but also shows the same trend.

The latter source also has a more detailed breakdown of building years. But even the former source mentions 1977 as its index year which already alleviates the external effects of WW2, people did not just live without houses for 30 years, the lost housing of WW2 was mostly rebuilt in the 50s.

Also, I do think that your claim is not valid. I do understand that the source I gave for economic lifetime, and also the norm I quoted is acting with fictions required for taxes and accounting reasons. The thing is: These fictions are intended to reflect reality. So I don't get why you are so hung up on where these calculation models originate, as they are specifically designed to reflect reality. If they were outlandish, especially when lifetimes on average are longer, these calculation models would absolutely be changed because then the state earns more money due to lower depreciation. If it was the other way around, the calculation model would be challenged in court.

Of course there is no natural law that a house collapses after 100 years. But not only in architecture, in all of engineering, it usually does not make sense to design for an infinite lifetime. If you double the lifetime of anything, it will cost a lot more money. Why would you spend more money today to build a house with better materials, when you don't even live to see the rewards in the form of lower maintenance and renovation costs in a 100 years. By extension this applies for the amount of money you want to spend in maintenance, at least for natural persons. In many situation it makes sense to simply use up the bound capital.

Now this leads to the following:

> It's easy to call someone irrational - but why do you think they don't want this work to be performed. How comes? I doubt that you assume they want the planet to die, so what do you think are their reasons?

As an anecdote for illustration, my grandparents still heat with oil, but the heater soon needs to be replaced. My grandparents are absolutely stubborn in that they want to replace it with a completely new oil-based heater. The literally only reason is: They are old and don't want to try out something new, even if it is functionally exactly the same (like a wood pellet heater). I literally offered them to pay 100% of the new heating system (reversible heat-pump because heat is one of the primary killers of elderly people and I would like my grand-parents to be around a bit longer...) after they bought heating oil on the ATH this spring and they still disagree. There is literally no economic incentive of looking the gift horse in the mouth, and they are unable to offer any other rational explanation.

You may also skimp on maintenance because you think "I am going to die soon anyways". Or people are planning to be living in a large 200 square-meter mansion with 3 stories until they are 90 when in reality they sell the house at 60 and suffer the loss of value when re-selling due to insufficient maintenance.

And some people just want to live in their house and don't give any thought to it until there is an emergency. Then people will have expensive repairs and still won't think twice about changing their behavior.

Some small house owners skimp on maintenance because they bought their houses as an "investment", and they are dependent on rent income to reliably subsidize their life. Even when the income could be higher in the future with some investments and quickly ROI, they won't accept saving up for it and taking on the economic risk.

Even for institutional housing owners it makes sense to tear down units eventually, even if it is just to get rid of the long-term tenants who make larger renovations annoying to impossible.

There is a lot of small house-owners and in general, most people are just really bad at basic accounting.
This is also a big reason why the housing market in general is such a pain in the ass.