Debevoise & Plimpton has inked a 20-year lease for its New York headquarters at a West Side Manhattan skyscraper, the Spiral, now under development.

The firm, leasing 530,000 rentable square feet, expects to move in the second half of 2022, Debevoise confirmed Tuesday.

Debevoise was close to signing a lease for space in 50 Hudson Yards, one of the Related buildings, the New York Law Journal previously reported. But a massive Facebook deal for 1.5 million square feet, largely in 50 Hudson Yards, prompted Debevoise to look to the Spiral instead as a replacement for its current offices at 919 Third Ave., according to a Wall Street Journal report.

In an interview, Michael Blair, the firm's presiding partner, said the new lease is for 13 floors, from the 40th to the 52nd, with options to scale up or scale down as the lease period advances. An investor document from landlord SL Green Realty Corp. states that Debevoise is currently leasing 577,000 square feet at 919 Third Ave., but Blair said the area of its new office will be comparable to the space it occupies now because some of its current space is subleased.

As the move-in date draws nearer, Debevoise will hold a contest to find a company to conduct a custom build-out of its space in the Spiral, he said. The building's modern design techniques, for example, arraying support columns around the building's exterior, rather than through office space, and the fact that lawyering now requires less paper and document storage will mean the firm will be able to fit more lawyers and staff in the same amount of space, Blair said.

The SL Green document said Debevoise is paying about $82 per square foot for its current space, or about $47.4 million per year. Blair declined to comment on those figures, but asked how the new space compares, he said, "The cost per square foot is higher [than the firm's current office], but with the additional efficiency, in the end, the cost per lawyer is lower." He said that assumes a moderate growth rate in lawyer head count over the next two years.

When completed, the Spiral's address will be 66 Hudson Blvd. It is situated just north of several other new Hudson Yards skyscrapers, occupying the space bound by 34th Street on the south, 35th Street on the north, 10th Avenue on the east and Bella Abzug Park on the west.

Debevoise's move would put it a stone's throw from other firms that have moved to new towers in the Hudson Yards neighborhood, such as Milbank and Boies Schiller Flexner.

The Spiral, a 65-story tower designed by Bjarke Ingels Group and developed by Tishman Speyer, is one of several projects ongoing near the Related Cos.' Hudson Yards development. Its defining feature is a spiral of terraces that twists around the building's exterior, giving workers and visitors the chance to get fresh air without going down to ground level.

"To my knowledge, there's no other building where there's outdoor space on every floor," Blair said. He added that the new offices will also feature more natural light than the current space.

Blair declined to comment on reports that Facebook's move resulted in the firm losing space at 50 Hudson Yards. "Tishman Speyer was great to work with, and we have a very efficient process with them," he said. "There wasn't any element of a setback, from our standpoint."