JPMorgan Chase is reportedly evaluating whether to construct a new skyscraper on its long-owned Riverside South site in Canary Wharf after concluding that revamping its current European base at 25 Bank Street could be costly and disruptive.

According to the Financial Times, the US bank has begun detailed due-diligence work on the dormant plot, bought in 2008, as it searches for room to accommodate a workforce that has swelled to 22,000 in the United Kingdom.

The investment bank occupies the former Lehman Brothers tower it acquired during the financial crisis, but that building is “relatively dated and will need upgrading if JPMorgan is to remain there”, people familiar with the planning process told the FT. A large-scale refurbishment would also force staff into temporary offices for several years, and executives view a fresh build as the cleaner option.

While a final decision has not been made, the bank has already leased 150,000 square feet at One Cabot Square, Credit Suisse’s former headquarters, to relieve short-term crowding. The tenancy, reported by the Daily Telegraph earlier this year, offers expansion rights over as much as half the 540,000-square-foot tower and will house staff returning to the office full-time. “The space is also viewed as an interim solution for JPMorgan’s staff ahead of any longer-term decision about a refurbishment at the office tower,” the newspaper wrote.

Riverside South already has foundations and basement levels in place after work carried out before the 2008 downturn, which bankers argue would shorten the construction timetable should the project proceed. A new tower would be a fillip for Canary Wharf Group, whose estate has suffered high-profile departures including HSBC and Clifford Chance. Vacancy concerns have pushed some landlords to convert office floors to education, retail and residential uses, yet valuations are showing tentative recovery as new tenants sign leases.

Refitting skyscrapers is proving expensive for rivals. Citi’s overhaul of its own Canary Wharf building is expected to exceed £1 billion, a figure JPMorgan executives cite when weighing their options. The choice is further complicated by the bank’s purchase of a Foster + Partners-designed headquarters in New York, set to open later this month, which absorbs significant capital.

JPMorgan declined to comment on its London plans. Market observers say a commitment to Riverside South would signal confidence in the docklands district and give the lender a modern, energy-efficient base large enough for its growing Chase UK retail arm.

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