I have worked in building maintenance and repair. One thing that is extremely hazardous to a concrete building is too much water. I have seen many concrete planters that crack and result in water leaks for lower levels. Standing water in concrete structures is a huge no no. I do not have a lot of experience in engineering on this matter, but whenever I see a solar punk sky scraper with vegetation on its exterior, I think "cool, but maintenance and inspection must be horrible! Repairs must cost a fortune when those roots and moisture degree the concrete."
What engineering controls does one need to create a durable structure while exposed to constant moisture needed for vegetation, and the vegetation itself? I know there are green sky scrapers with gardens all over. What is the maintenance of those structures? Do they hold up\last as long as bare concrete structures?
I like neighborhoods and cities with mid or low rise housing. I spent a lot of time in Turin, Italy (I'm American) and most that city (and other European cities) have mid rise apartments. They're in the 6 to 8 story range a lot of times, but still no high rises. It makes for a great walkable city. The street I lived on in Turin was this huge wide boulevard that probably could have accommodated six to eight lanes of traffic with a turn lane in the middle. Instead there was a two-lane road in the middle with turn lanes, followed by streetcar rails further out, then a line of gorgeous trees, then parking for local businesses, then a side street to access the local parking and finally a nice wide sidewalk in front of the shops and apartments.
It's a great looking city for anyone who happens to be in Northwest Italy!
Christopher Alexander picked the Four Story Limit for aesthetic and mental reasons – but historically, older buildings were generally limited to four stories because of climbing too many stairs – the six to eight story limit of most European city cores comes from the introduction of the first elevators that couldn’t really handle more than six stories