(CNN) — New York City is counting on office-to-apartment conversions to help relieve its housing shortage. But after structural problems earlier this month threatened a partial collapse at one of the city’s largest such projects, regulators have intensified scrutiny.
Since then, three more Manhattan office conversion projects have been ordered to partially pause or halt construction this month over issues ranging from missing paperwork to cracks in concrete beams.
Most recently, inspectors from New York City’s Department of Buildings issued a partial work stoppage this week at 750 Third Avenue after finding unapproved modifications to several steel columns in the building, according to an online database from the agency.
The 34-story office tower, built in the 1950s, is undergoing a conversion into roughly 678 apartments, according to its architect, Gensler.
The project is located not far from the former Pfizer headquarters on East 42nd Street, where structural columns buckled and floors sagged on July 7 during its conversion into roughly 1,600 apartments. The incident prompted city officials to evacuate several surrounding buildings and reroute nearby bus lines over fears of a partial collapse.
The New York Times first reported the partial work stoppage at 750 Third Avenue on Wednesday.
Office-to-apartment conversions have surged since the pandemic emptied out aging office buildings, offering cities a way to add desperately needed housing. And New York City has championed these conversions, offering tax incentives to turn older vacant office buildings into livable spaces.
But the projects often require extensive structural, plumbing, mechanical and redesign work that can make the project more complicated than building new housing from scratch.
The string of work stoppages reflects heightened scrutiny of one of New York City’s primary housing strategies. Meanwhile, officials are racing to ensure older office buildings can be safely transformed into apartments.
Ever since the issues at the Pfizer project, also led by Gensler, the city has ramped up inspections at other construction sites, said Ryan Degan, a spokesman for the city’s Department of Buildings. Degan did not disclose which other projects are being targeted for inspection, though he said the city can issue thousands of stop-work orders per year.
Gensler did not immediately respond to CNN’s request for comment on Wednesday.
The Tuesday inspection at 750 Third Avenue found several steel columns with welded splices, which are commonly used to join two pieces of steel when a single beam is impractical because of space or weight constraints. But when inspectors asked for documentation showing the Department of Buildings had approved their use, the contractor did not provide it, the agency said.
In a statement, SL Green, the building’s owner, said it had submitted a request to the city to rescind the partial work stop order.
“During our structural reinforcement prep work, prior to beginning any overbuild work, we identified an on-site condition that differed from the plans that were submitted to the City, which was visible only after completing initial preparation work,” a spokesperson said.
“There are no structural issues with the building, and we are already working with the licensed professional engineer of record to address this condition,” they added.
Two other office-to-apartment conversion projects in Manhattan were paused this month as well, Department of Buildings said.
At 77 Water Street, a 26-story office building was being converted into a 33-story residential building with 647 units in the city’s Financial District. City inspectors soon found site safety issues, including workers who were operating machinery without proper certification and an unpermitted supported scaffold in use, according to the Department of Buildings. As a result, the agency issued several partial work stoppage orders.
However, two weeks ago, a re-inspection found that the safety issues had been corrected, and work was allowed to continue.
An inspection this month at a separate Financial District office conversion project revealed a deeper issue: Concrete beams in the building had cracked and were repaired without properly notifying the city, according to the Department of Buildings.
The beams, in a 32-story project at 222 Broadway expected to yield nearly 800 apartment units, had been wrapped in steel as a makeshift fix, the agency said.
Although Department of Buildings engineers said they did not believe the building needed to be evacuated, last week the agency escalated a partial work stoppage to a full stop-work order until engineers on site provide a complete explanation of what caused the cracks and how they were repaired. As of Wednesday, the full stop-work order remained in effect, according to the agency. The agency is now reviewing requested reports from the engineer of record.
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