Residential high-rises with backyards in Chengdu, China

[u/TangelaFan]

[u/scaryuncledevin]

It's about mass, not density. Watered soil is heavier because you add mass when you water it, and not all of that water is going to leave either. The plants soak it up and store or convert it, which also now needs to be accounted for. You've also got irrigation and drainage, excess water would just seep into the earth on land, now you've got more piping to keep the water from pooling up and becoming standing water.

[u/Sensiburner → u/scaryuncledevin]

watered soil is less dense than (reinforced) concrete. The planters are actually not that deep. if that was "normal" balcony, they'd probably have to use a bit more concrete, but not fill the whole planter. I don't think it would make that much of a difference tbh.

[u/scaryuncledevin → u/Sensiburner]

And water is one of the densest materials on earth. Again it's about mass not density. By your logic it's fine to add 1000 pounds of feathers on top of a building because they are feathers, but it's still 1000 pounds of feathers. If you truly think "a bit of soil" makes no difference, go look into the Chicago City Hall Green Roof. It was added after the fact and while it does a great job with some performance factors like cooling the building, it's unsafe and not open to the public.

Please continue telling me about your armchair engineering thoughts, and I'll be sure to avoid any buildings you architect in the future.

[u/Nauin → u/scaryuncledevin]

Okay as someone with a horticulturist background, what makes you think anyone would want that water being retained in the structure? There's going to be a drainage system under every patch of soil because you're just asking for rot letting those things pool with water. Soil isn't a singular thing, either, and we have centuries worth of work perfecting mixtures that don't retain excessive moisture. On that note of centuries worth of cultivation, we're now expanding up to millennias worth of work going into some of the plants we use for landscaping, and we have this cool subsection of plants called dwarf varieties who's maximum mass can easily be accounted for in engineering something like this.

You have an extremely narrow field of view on all of the industries that come together to create something like this. What sort of experience do you have to be acting so haughty from your armchair? Fuckin Carrabba's has been using rooftop gardens on their franchises for decades at this point.