The construction of tall buildings in the capital costs 40% more than it did six years ago, outstripping increases in other major cities, according to a report by professional services provider Turner & Townsend.

The cost of building towers over 20 storeys is second only to New York and now exceeds Seoul by more than three times and Mumbai by 10 times, said Turner & Townsend, which has helped to deliver around 200 tall buildings globally.

The report focuses on London, New York, Seoul, Tokyo, Mumbai and Dubai. It identifies office shell and core costs of $6,900 to $8,700 (£5,150 to £6,500) per square metre of gross internal area (GIA) for the UK capital, behind New York’s $7,000 to $9,700 (£5,220 to £7,234).

It shows cost rises result from factors including conflicts and geopolitical events, significant regulatory changes, enhancements to the product and challenging trading conditions following Brexit.

According to Turner & Townsend, demand for high-quality, sustainable space remains strong, with some large investors using their ability to take a longer-term view to get their towers into a favourable letting market.

“As a result, it is still possible to deliver a high-quality, financially successful skyscraper in London, but only if project teams work together to address viability issues from the outset,” it added.

The analysis also reveals the shape of a skyscraper is as important as height when it comes to overall cost. “In a city like London, there can be a 25% difference in price between the most ambitious and the most cost-efficient projects, with massing being a key determining factor,” the firm said in the report.

Steve Watts, head of tall buildings at Turner & Townsend, added: “With elevated construction costs further pressured by continuing inflation, as well as unfriendly financing conditions and softened yields, viability is now the most pressing issue, and doing more with less is the order of the day in a lot of markets, particularly London.

“Now, more than ever, it is important to recognise that shape is as important as height when it comes to delivering a project cost-efficiently, and there is an ever-increasing focus on ensuring tall buildings are integrated into the broader cityscape, whether that is by offering public amenities or a greater range of uses on the ground floors.”