Column buckling halts major Manhattan office-to-apartment conversion

Two steel columns on the 21st floor of the former Pfizer headquarters in midtown Manhattan buckled this week, forcing evacuations and temporarily stopping work on a large office-to-apartment conversion that would add about 1,600 units. The project involves adding more than a dozen stories to a 1960s office tower and threading a new 30-story concrete tower through a 1909 building. Temporary supports have been installed while city officials and engineers assess the failure.

Engineering experts said the incident highlights the technical challenges of adaptive-reuse projects, which must ensure older structures can bear new loads and accommodate residential layouts. “I don’t think it really brings into question our understanding of how to do something like this,” said Ben Schafer, a structural engineering professor at Johns Hopkins University.

Schafer explained that the historic building is likely to retain its own load-bearing capacity while a new structural system supports the added floors, requiring careful integration of the two systems. He added that the newer tower’s conversion involves cutting openings in the existing floor plate to provide light for apartments while still supporting the additional weight.

The cause of the buckling has not been determined, but both Schafer and structural engineer Emily Guglielmo suspect the added load may have exceeded design assumptions. Nathan Berman, founder of developer MetroLoft, previously told the Wall Street Journal that widening the top 15 floors likely contributed to the damage.

Guglielmo noted that adding stories to existing buildings is common in dense urban areas but requires thorough review of original construction documents and inspections. “In cities and towns that don’t have that available geography, you’re going to see a lot more of this type of design where there’s an adaptive reuse to an existing building,” she said.

The incident comes as New York City pushes office-to-housing conversions to address a housing shortage, with zoning changes and tax incentives spurring dozens of projects. Joshua Harris, director of Fordham University’s Real Estate Institute, said such conversions are essential despite inherent risks, describing them as “very, very complicated surgical procedures” on old structures.

Experts emphasized that strong building codes and experienced crews make such failures rare. “We’re very fortunate here in the United States that we are not seeing these types of failures on a day-to-day basis,” Guglielmo said. Harris added that the incident may prompt a review of other approved projects to ensure similar issues are avoided.