A Manhattan building that once was the Pfizer headquarters threatened to partially collapse on Tuesday, blocking off several streets in East Midtown.
The building at 235 East 42nd Street was under construction, in the middle of a conversion that would transform it from offices to about 1,600 apartments. Office conversions have gained traction in recent years as the country’s housing supply has been stretched thin and offices often have sat vacant as more people work from home.
The New York City Council’s approval of “City of Yes for Housing Opportunity” in 2024 made office-to-residential conversions easier by relaxing restrictions that prohibited buildings from making this change.
But transforming conference rooms into bedrooms and kitchens comes with a unique set of challenges, including zoning requirements and logistical obstacles.
What makes this kind of conversion so difficult?
One reason large modern office buildings are hard to convert is because they are generally so deep. Dozens of cubicles can be stuffed into the interior of a building, far from any sunlight, but bedrooms, which require windows, cannot be. This makes every individual project into a puzzle: Where can new windows be added? Where are the structural support beams? Where are the elevator shafts?
“Light and air are the biggest challenges we have,” said Avinash K. Malhotra, an architect who has designed many office-to-residential conversions, including 180 Water Street in Manhattan. To get enough light and ventilation into 180 Water Street, the developers cut a hole in the center of the building to create an interior courtyard. Mr. Malhotra said this was only possible because the elevator shafts were at one end of the building, rather than in the middle.
Older office buildings tend to be easier to convert because they’re narrower, with more interior space that are near — or near enough — to the windows.
The conversion of the former Pfizer headquarters was planned to be the biggest in New York City and also called for adding more stories to part of the structure, contributing to the complexity.
How can you add floors to a building that’s already standing?
Office buildings are generally designed to hold more weight per square foot than residential buildings, which means a foundation might be able to handle additional floors. The support columns, however, might not be strong enough to take the additional load, Mr. Malhotra said, so they have to be reinforced.
“Adding on top of the building is tricky,” Mr. Malhotra said. A building might have been designed to hold more weight, “but it was designed 100 years ago,” he said. “You don’t know if there’s metal fatigue or how well the building was maintained.”
The project’s developer cited the widening of additional top floors as the reason for the destabilization, according to The Wall Street Journal. The issue came to light after construction workers found that a steel beam was compromised on the 21st floor, according to officials. The Fire Department said that two support columns inside the building were buckling and several floors were sagging.
Is doing a conversion more challenging than building from the ground up?
Abi Aghayere, a professor of structural engineering at Drexel University likened office to residential renovations to “structural gymnastics.” During those intermediate stages, a lot of work would be happening in the building that could give rise to potential problems. For example, beams that support columns that bear vertical loads might be moved. Those types of problems could emerge because of a faulty design, or from the error of the construction workers.
“There’s going to be a lot of cutting of holes and slabs and all that to make room for all the HVAC and the plumbing for each individual residential unit,” he said.
What buildings have already been converted from offices to apartments?
There have been five office-to-residential conversions completed in Manhattan since 2020, adding more than 3,000 homes, according to the Department of City Planning.
As a way to encourage developers to undertake these types of projects, state legislators created a new tax exemption called 467-m for office-to-residential conversions where 25 percent of the apartments are income restricted.
Before 467-m, office-to-apartment conversions were spurred by a different tax exemption program in Lower Manhattan, which led to the creation of 12,900 apartments between 1995 and 2006.
Mihir Zaveri contributed reporting.
The post What to Know About Manhattan Office Conversions appeared first on New York Times.
