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?
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