China’s Sky City: Tallest Building in the World in 90 Days

Throughout this year, there has been a substantial amount of interest and speculation about a Chinese project called Sky City – a 220-floor, 838 meter (2,749.3 foot) skyscraper planned for construction in the city of Changsha. What makes this building interesting is not just that it will be the tallest building in the world upon completion – indeed, many such projects have been recently announced and completed, seeming to just barely edge each other out – but instead, that the construction is planned to take only 90 days to complete. No, that is not a typo; 220 floors in three months. That is five floors per day plus interior work.

Can it be done? Well, there are a couple of considerations…

Before we go further, here are some more details about the building: the total floor space of the building will be nearly 4 million square ft – equal to about 1,455 American homes by average national square footage. It will cost about 1/3 as much as the Burj Khalifa (the world’s current tallest building) and house over 31,000 people.

When I initially heard of this, I called BS almost immediately. I mean, building a scyscraper that is half-a-mile tall in one year sounds crazy, let alone three months. Now, I don’t know much about commercial construction, but my basis for this rests in something known in economics as “the law of diminishing returns”. Basically, this principle says that after a certain point, every extra person that you add to a task will increase productivity by less than the person added before them.

To illustrate this concept, imagine you have a huge pile of bricks, and you want to build a wall that is 20 bricks long and 100 bricks high. One person would have to pick up a brick, carry it 100 feet to the site of the wall, and set it down. At this rate, that person can lay 1 brick per minute. Then, say that 19 of your friends come help you – you can each lay a brick every minute, so the group rate of productivity goes up to laying 20 bricks per minute. Then, add another thirty people; things start to get crowded, and several people have to stand by the wall holding their bricks until the 20 people in line in front of them have laid their 20 bricks and completed a row. at that point, the rate of brick-laying might only increase to 40 bricks per minute, meaning that the additional 30 people only increased productivity by being able to lay an additional 20 bricks per minute. Even with 1,000 people, the rate of brick laying probably stopped increasing around the 200th person, because the additional people only crowded the scene and didn’t allow the group to lay a bricks on the small, 20-brick long wall at an increased rate than before. On this basis, I assumed  that the massive manpower and resources of the Chinese would not allow them to build any faster than the physical constraints of the building site allowed them to.

As it turns out though, the firm constructing Sky City does things in a completely different way: they prefabricate modular parts of the building, bring them to the site, and then put them together there – sort of like how all the Lego pieces come in a box and just require assembly. They demonstrated the efficiency of this model when, in 2011, they constructed a 30-story hotel in only 15 days. The video below details this process.


Of course, the ambitious goal of Sky City is not without its critics. Some say that the surprisingly low cost is indicative of the low quality of the materials used, and that shortcuts will inevitable be taken given such high pressure for the company to meet its stated timetable. Others worry that with so many people in the tower, it would be very difficult to evacuate everybody safely in case of an earthquake or fire.

The current status of the project is slightly in limbo; it has preliminary approval from the Chinese government, and full approval is expected to come within a matter of days. With construction beginning in late December, we could see this thing completed by March 2013. I personally think it would be interesting, but I hope they take extra precautions to avoid a massive tragedy.

CONCLUSION: It probably can be done, but not safely. If anybody could do it though…it would be the Chinese.

Do you think it is possible? Let us know below.


3 thoughts on “China’s Sky City: Tallest Building in the World in 90 Days

  1. Pingback: Modular skyscrapers | Confessions of a Common Man

  2. I generally don’t like adds, but I will forgive you for Coldwater Creek, my favorite store. They should take a good look at the Hyatt tragedy in KC a couple decades back. There for years, then catastrophic structural death, both to the “famous” walkway and the large number of people on it. Time only tells the story of a stack of cards vs the Pyramids.

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