Slender supertall buildings with height-to-width ratios exceeding 5:1 experience vortex shedding, where wind separates at corners and creates alternating low-pressure eddies that cause rhythmic swaying perpendicular to wind direction; this phenomenon requires specialized engineering solutions such as tuned mass dampers or aerodynamic shaping to ensure structural stability and occupant comfort.
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New York's Billion-Dollar Pencil Towers Are Swaying. The Fix Made It WorseAdded:
The chairman of the company that built 432 Park Avenue once described the noise inside as intolerable and said it made sleep difficult in even moderate weather. The line appears in a lawsuit filed by his own residence. The top of the tower held the largest tuned mass damper system ever installed in a super tall two pendulums of 660 tons each engineered to hold the building still against the wind. By the time the suit was filed the dampers were reportedly malfunctioning. What had gone wrong with the fix was harder to explain than what had gone wrong with the building. For a few years after the financial crisis, Manhattan real estate found a new shape.
It was tall and narrow. Land in Midtown was finite but air was not and zoning rules around Central Park let developers stack 15 as the unused air rights of older neighbors into a single sliver of footprint. The result was the pencil tower, a residential super tall built on a parcel that would once have held a modest hotel or office block. Harry Macklowe bought the Drake Hotel site at Park Avenue and 57th Street in 2006 and held it through the downturn. By 2011 foundation work was underway on what would become 432 Park Avenue. The architect was Rafael ViΓ±oly, Uruguayan born and based in New York where he had founded his firm in 1983. His design was a single geometric idea repeated up the sky line. The tower would be a perfect square in plan, 93 ft on each side, wrapped in a grid of 10-ft windows set into a white concrete exoskeleton. No setbacks, no taper. Structural engineering went to WSP Cantor Seinuk.
Wind tunnel work went to RWDI in Ontario. The building topped out in October 2014 and was completed by the end of the following year at a reported construction cost of 1.25 billion dollars. A few blocks away, two other projects were moving at a similar pace.
220 Central Park South, developed by Vornado Realty Trust and designed by Robert A.M. Stern, broke ground in 2013 and would reach 950 feet by 2018.
The third project, 111 West 57th Street, would not finish 2021.
When it did, it would be the thinnest skyscraper in the world, 1,428 feet tall and only 60 feet wide, a height-to-width ratio of 24 to 1. The buyers came from every continent.
Penthouse listings ran into the 80s of millions. Inside the marketing materials, the towers were described as homes in the sky with private restaurants, indoor pools, and 24-hour concierges. Residents began moving into 432 Park in late 2015. For a short period, the building did what it was meant to do. The first warning was a sound. Residents heard it on windy nights, a slow creaking through the walls and ceilings, sometimes a pop or a thump that traveled through the floor.
One acoustic consultant later said the noises in the pencil tower she worked on reminded her of guns going off. Snap, crackle, pop, she called it. The buildings were safe, she said, but the noise was hard to live with.
Then the elevators began to fail. The Schindler system at 432 Park was programmed to slow or shut down when the tower moved past a set threshold of sway. A resident going to the 81st floor would find the cab decelerating in the shaft, sometimes stopping between floors. In one episode cited in the 2021 complaint, a resident was trapped inside an elevator for over an hour while the building rocked above the city. The trash chute was reported to make a noise like a bomb when used. Water came next.
Court filings would later document more than 20 leaks across the building between 2017 and 2021. In November 2018, a major break sent water down through several floors at once. Pipe joints were failing. Sealant was failing. Mechanical systems were failing in ways that did not seem connected at first until residents began to notice the pattern.
The problems were worst when the wind picked up. Outside, on the white concrete face of the tower, the cracks were appearing. They were small at first, then larger, then in places where chunks of material seemed to have separated from the structure. An engineer later told The New York Times that water could begin seeping into the cracks and compromising the building from the inside out. He said chunks of concrete could fall, that windows could loosen, that the building could become uninhabitable. He was not involved in the original project. By 2021, the condo board had retained its own engineering consultant. The consultant identified more than 1,500 construction and design defects. Many were described in the filing as life safety issues. The board sued the developers for $250 million.
None of it, residents said, was the experience they had been sold.
Something inside the buildings was working against them, and no one had a single name for it yet. To understand why these towers behave the way they do, you have to understand what wind does to a slender object. When air flows past a tall building, it does not simply press against the upwind side. It separates at the corners and rolls into spinning eddies behind the structure, peeling away in alternating directions. Each eddy creates a brief low-pressure zone that pulls the building toward it. The pull alternates from one side to the other at a regular frequency. Engineers call the phenomenon vortex shedding, and in a tall, slender tower, it can set the structure rocking from side to side perpendicular to the wind direction, like a metronome being tapped by the air itself. Skyscrapers are considered wind sensitive when their height-to-width ratio passes about 5:1. The ratio at 432 is 15:1. At 220 Central Park South, it is 18:1. At 111 West 57th Street, it is 24:1.
RWDI's early wind tunnel testing on 432 Park found that even in light winds, the tower would shed vortices strongly enough to vibrate. Most supertalls have addressed the problem at the level of shape. The Burj Khalifa narrows as it rises, twists in plan, and breaks the wind into uneven streams that cannot organize into a coherent shedding pattern. It carries no supplemental damping system at all. Its aerodynamic geometry does the work. Other recent supertalls in Asia and the Middle East have taken similar paths, tapering, fluting, or rotating their footprints to scatter the wind. 432 Park Avenue could not do this. Vinoly's design was fixed, a perfect square repeated 96 times into the sky, was the architectural premise of the project. The engineers at WSP were not given the option of reshaping the form. They had to fight the wind by other means. They added open mechanical floors every 12 stories so air could pass through the building rather than around it. They thickened the upper slabs to 18 inches to add mass and resist displacement. And on the top, in a corridor on either side of the building's core, they installed two opposed pendulums of 660 tons each. It was the largest tuned mass damper system ever placed in a super tall residential tower. One independent engineer would later describe the approach as audacious and somewhat risky. The dampers did not stop the vortex shedding. They only absorbed the building's response to it.
The wind was still going to push. What is documented sits in two long court filings. The first, brought by the 432 condo board against the developers in September 2021, runs through more than 1,500 alleged defects. It describes the noise and vibration as one of the building's most persistent and disruptive problems.
It describes elevators stopping in shafts during high wind. It describes flooding and flooding from failed plumbing connections, power outages that shut down air conditioning, and a chairman of the developer's own company calling conditions intolerable in writing. The complaint seeks $250 million.
The developer, CIM Group, has stated publicly that it denies the allegations and that the building has performed remarkably well. The second filing arrived in 2025.
It names not only the developers but the architecture and engineering firms involved in the project. It alleges that the facade is plagued with thousands of severe cracks, spalling, and other forms of deterioration. It states that water has infiltrated the structure, that steel rebar inside the reinforced concrete columns has begun to corrode, and that a 10-in deep crack runs through the building's around the building's core. The owners argue that the developers concealed the extent of the damage. CIM has said it will move to dismiss. The independent technical commentary is more cautious. Steve Bongiorno, a structural engineer with no role in the original project, has examined videos of the towers tuned mass dampers in operation. He has reported that the damper mass appeared to be swinging as much as 3 ft in each direction during a modest wind event with the viscous damping devices stroking nearly a foot and a half. Those numbers, he wrote, seem excessive for the wind speeds at the time. The viscous dampers have been repaired more than once. Whether the malfunction is the cause of the building's problems or a symptom of something else, he has stated plainly is not yet known.
The New York City Department of Buildings confirmed that 432 Park passed its most recent facade inspection in 2023.
A University College London Professor of structural engineering, Jose Torero, has said separately that the level of distress in a building of this age is highly unusual. None of the parties involved in the original design have spoken publicly about what they think is going wrong. The engineering record is incomplete and what comes next in court will likely fill in only some of it.
The numbers attached to the building have grown harder to ignore. Independent estimates put the facade renovation at roughly $160 million spread across a 3-year program of repairs intended to halt the cracking, restore the concrete, and protect the steel inside from further corrosion.
That is on top of the $250 million the condo board is seeking in its original suit and the additional damages sought in the 2025 complaint. The 125 units in the building originally sold for a combined $2.5 billion.
The cost of keeping them functional, by the residents own accounting, is now a meaningful fraction of what they paid.
Some owners have spent extended periods outside the building. One resident, according to the 2021 filing, was forced to leave for more than 19 months while remediation work was carried out in their unit, much of it during the pandemic. Others have described moving family members out during windy seasons.
Resale activity in the tower has slowed.
Several units have come back to the market at prices below their original purchase amounts, an unusual pattern for a property of this profile in Midtown Manhattan. The elevator issue has its own arithmetic. The cabs are programmed slow or stop when sensors detect the building moving past a defined threshold. When the dampers underperform, the threshold is reached more often. Residents on upper floors have reported being stranded for stretches that exceeded an hour. The system was designed to protect them. It is now also the thing that strangles them. The cracking concrete carries the most public risk. Engineers have warned that loose material from extreme heights falling onto crowded Midtown sidewalks would not be a minor event. Routine facade inspections under New York's local law have so far cleared the building, but those inspections look at a moment in time, not at a trajectory.
The trajectory, according to independent commentary, is the part that worries them. Across Billionaires' Row, the implications have spread. 220 Central Park South has faced its own neighbor lawsuit over construction damage to the adjacent landmarked co-op. 111 West 57th Street has had to absorb public attention every time a video of its swaying top surfaces online. The market for slender super tall residential towers, briefly the most lucrative real estate product in New York, has cooled.
Developers who watched 432 Park Rise are watching its lawsuits now. The towers are still there. They're still selling.
Penthouses at 111 and West 57th continue to trade quietly to international buyers who view the units virtually. The lobby of 220 Central Park South still receives its residents through a private motor court off 58th Street. At 432 Park Avenue, the windows are still washed.
The private restaurant still serves dinner. The dampers at the top still swing through their corridors on either side of the core. The white concrete face of the tower, viewed from across the avenue, still reads as a single clean geometric line against the sky.
What has changed is the conversation around them. The pencil tower as a building type emerged from a specific moment, when zoning, capital, and engineering capability lined up to make extreme slenderness possible. It is not clear that moment will return in quite the same form. The structural firms that designed these buildings have learned what cannot be left to a tuned mass damper. The wind tunnel firms have learned how much aerodynamic shaping matters when the height-to-width ratio passes a certain point. The developers, several of them now defendants in active litigation, have learned what happens when residents move into a building still being calibrated. The court cases will continue for years. Some of the technical questions will be answered inside them in the unglamorous language of expert reports and deposition transcripts. Others may never be answered publicly at all. Whether the cracks in the facade reflect a problem with the concrete mix, the loading from sway, the joint design, the construction sequence, or some interaction between all four is the kind of question that engineering disputes rarely resolve cleanly. What can be said is narrower.
The decision to build a perfect square, 1,396 ft into the air without aerodynamic shaping, required the engineers to push damping technology to a scale never before attempted in a residential super tall. The damping technology by multiple independent accounts is now under stress. The building is now under stress. The residents are now under stress. Whether the original design choice can be unwound by repair or whether the fix is now part of what needs fixing is the question the next decade in Midtown will answer. For now, the towers stand. They sway and the dampers swing.
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