Chinese skyscraper built in 19 working days

At the beginning of February, construction workers gathered at a sparse building site in the city of Changsha, south-central China.

A little under three weeks later, a 57-story skyscraper stood on the very same the spot.

The “Mini Sky City” tower is the work of Broad Sustainable Building, a Chinese firm that specializes in prefabricated construction.

By preparing more than 2,700 modules in a factory for four months before site work began, BSB says it was able to assemble the structure at the rate of three stories per day — like a giant vertical jigsaw pieced together from a minutely detailed set of instructions.

A timelapse video of construction went viral on Chinese websites before finding its way onto many western news sites and broadcast media at the beginning of May.

Need for speed

To put the pace of BSB’s construction into context, it took almost five years to build London’s 37-story Walkie Talkie building which opened in August 2014.

Although some may point out that the Changsha tower is less architecturally distinct than the likes of the 20 Fenchurch Street (the official name of the Walkie Talkie), the Chinese skyscraper remains a considerable structure with more than 800 apartments and office space for 4,000 workers.

The first 20 floors of Mini Sky City were already completed at the end of 2014 before construction was delayed, BSB’s senior vice president Juliet Jiang told CNN by email.

The remaining 37 stories were then assembled between January 31 and February 17 — a mere fraction of the time it took to build the same number of floors that make up the Walkie Talkie in its entirety.

“One hundred percent (of the) parts are factory-made,” Jiang said of BSB’s methods. “We don’t waste any materials, no one is idle in the workshop or on site. We have very good planning.”

Jiang said that the processes employed by the firm are also far more cost effective, environmentally friendly and lead to less disruption in cities during construction.

BSB is now reportedly keen to put its techniques further to the test by seeking permission to build an 838-meter-tall (2,749 ft) skyscraper in Changsha, a project first announced in 2013.

If built in the stated ambitious 10 month time-frame, the “Sky City” structure would be the tallest building in the world until the Kingdom Tower in Jeddah, Saudi Arabia, is completed.

Yet a 2014 article in the China Daily newspaper stated experts believed the delay in construction likely meant BSB had previously failed safety inspections.

The official newspaper of China’s ruling Communist Party, The People’s Daily, also reportedly criticized the project on its Weibo feed as a display of “blind worship for ultrahigh skyscrapers.”

BSB chairman Zhang Yue even published an open letter answering criticisms of the proposed building.

Concerns around potential future projects aside, Jiang was keen to point the potential for exporting BSB’s building techniques to locations outside Changsha.

In China the need to build fast is acute. The world’s most populous nation is home to 1.4 billion people and has experienced an exodus from rural areas to its urban centers in recent decades.

Just 31% of China’s population lived in cities in 1995, according to World Bank data. By 2013 the urban population had risen to 53%, equating to more than 300 million extra people living in the country’s cities.

That figure would likely have been even greater were it not for China’s “hukou” system which limits migrants’ access to social services such as education and health care when away from their home region.