News: construction is set to begin next month on the world's tallest building in Changsha, China, which will be completed in just 90 days.

Construction firm Broad Sustainable Building (BSB), a subsidiary of China's Broad Group, has corrected earlier reports that its 220-storey Sky City tower would take seven months to complete, telling ConstructionWeekOnline that the skyscraper will be finished at the end of March next year.

Following foundation work that will continue until the end of December, the company said its schedule to construct the 838-metre tower "will go on as planned with the completion of five storeys a day."

"We have not issued any press statement on this and it will go on as planned... we have not said anything about 210 days," said Broad Group senior VP Juliet Jiang, adding that the project is still awaiting approval from the government.

As previously reported on Dezeen, BSB plans to build the tower using pre-fabricated components that slot together like a Meccano toy. On completion, the skyscraper would be taller than Dubai’s Burj Khalifa and include schools, a hospital, 17 helipads and apartments for over 30,000 people. The company has already successfully demonstrated its approach on a smaller scale by constructing a 30-storey tower in 15 days.

Above: composite image comparing an earlier design for Sky City with the Chicago skyline

Broad's CEO Zhang Ye claims his pre-fabricated towers are designed with a different load-bearing structure to conventional towers so that they use less concrete and steel and can be produced in factories rather than on-site.

However, some construction experts believe the tower is simply too tall to be built with ready-made parts. Bart Leclercq, head of structures in the Middle East at WSP, the engineering firm behind The Shard in London, warned that documents for Sky City on BSB’s website make no mention of wind load.

"There are forces working on a building that tall, including the wind. It is not a minor thing at that height," he told ConstructionWeekOnline. "By just using these simple units all put together, you are not going to get enough stiffness; this building will have an enormous storey drift, and it will sway."

Read our previous story about BSB's plans to build the world's tallest tower from pre-fabricated parts, or see all our stories about skyscrapers.

Above: image shows how Sky City will look once completed in Changsha

Lyndon Neri and Rossana Hu of Shanghai studio Neri&Hu recently told Dezeen that their fellow architects in China are "lost" and need to stem the tide of “half-assed” building projects in the country, while Aric Chen, the creative director of Beijing Design Week, had previously warned that China needs to “slow down” and pay more attention to issues of authenticity, process and identity.

In contrast, Hong Kong-based designer Michael Young told Dezeen earlier this month that China is now "a dream scenario" for designers, with its huge manufacturing base and plenty of investment opportunities on the horizon.

See all our stories about China »

Images are courtesy of Broad Group.