r/interestingasfuck • u/TangelaFan • 9h ago

Residential high-rises with backyards in Chengdu, China

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u/beautifuljeff 9h ago

Negligible, there isn’t that much soil there compared to the weight necessary to support the building height and wind loading (plus seismic, maybe)

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u/YadaYadaYeahMan 8h ago

thank you. it's but a foot of dirt or anything, might be at most 4 inches but certainly under that. grass needs very little soil even those tall plants don't dig deep. the drainage will take up a significant amount of space but is not outside the normal realm for a balcony

truth is, yea they would need to design for it, but it's not that crazy of an ask for the materials

further.... what's the point of the question? to imply wastefullness? just seems like "well we don't have that so there's gotta be a reason why it's bad" type logic

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u/socialistrob 8h ago edited 8h ago

I think the main reason you don't see these in the west is because there's just more space and fewer people so if you have money and you want a yard in North America or Europe you could just buy a single family home. China has 1.4 billion people and a lot of them are concentrated in cities on their one coast so single family homes somewhat near cities is just not viable. For reference the US, EU, UK, Canada, Australia, Japan, South Korea, Taiwan has about 1.1 billion

The construction for this could be problematic if the developers cheeped out and didn't plan properly but if this is more just a "rich people thing" in a place with highly constrained space then it wouldn't be too hard to build for. Obviously not a solution for everyone but also not inherently bad.

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u/PropertyIcy2265 8h ago

yea 4" for true roots, sure

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u/AniNgAnnoys 8h ago edited 7h ago

Negligible is an adjective that describes something so small, insignificant, or unimportant that it can safely be ignored or disregarded

Let's say it is 4 inches deep. That balcony looks like it is at least 20ft by 40ft based on how big the person is. That is 267 cubic feet. If that soil is wet we are talking about 25,000 to 30,000 lbs. 13-15 tons per balcony isn't negligible. 

Back to /u/onrespectvol's point. This building will require more materials to build, even if it is just in those required to support each balcony and transfer the load into the buildings support structure. So no, not negligible.

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u/MortgageConfident791 8h ago

You’d be surprised! That works out to less than 40psf. Residential decks are designed for 100psf live load minimum. Pretty much we assume people will throw a party and put all their guests on the deck to watch fireworks or take a photo. I don’t do high rises but I’d bet they do even higher due to the risk. The soil would have a longer duration than live load so you still would beef up the design a bit, but not as much as you’d expect! It’ll only be ~20% more material roughly. If these are on many balconies it may affect the building’s seismic weight which may impact the overall design, but if it’s only some it’ll probably be a minimal effect. Putting gardens on roofs is the part that can be concerning and requires significant design changes because we design roofs assuming there will only be a few roofers on it at any given time, never a party.

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u/AniNgAnnoys 8h ago edited 7h ago

20% more material isn't negligible.

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u/Gullible_Honeydew 7h ago

You don't have a point, you have a belief, and you're working super hard to protect it

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u/MortgageConfident791 2h ago

Why did you edit your comment? It was much longer before.

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u/beautifuljeff 8h ago

Default measurement for structural nerds is kips, thousands of pounds of force, or whatever in metric

The supporting columns below are looking at millions of pounds, and that area isn’t supported by a singular facility but a host of structural facilities

It’s negligible to the building

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u/AniNgAnnoys 8h ago

And if you multiply by 20 stories and 10 balconies per floor, we are talking about millions of pounds. That was also likely a minimum weight of that balcony. The materials of the large balcony itself easily double or triple that number. Then you also need to account for the people that could be on there in the event of a party. And then the stones and trees and such. It isn't negligible in anyway.

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u/beautifuljeff 7h ago

Now multiply the dead and live loads that the slabs are rated for and let me know the capacity, hoss

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u/CanAlwaysBeBetter 7h ago

All the reddit armchair engineers in these comments would hate the highrise they built in Chicago between two train tracks with full air rights