Built in the 1980s, 520 Madison offers premier office space in a prime location. To create more commercial space for tenants at the top of the 43rd floor—plus a 2,200sf landscaped terrace—the mechanical equipment room (MER) had to be relocated to the roof and elevator access extended to the top level. We were brought on to help create a dynamic approach that could get the job done within the tight timeframe.
Our approach consisted of constructing a unique scaffold system that extended down the building. To build safely on the roof at 570ft in the air, we prepared for every possible complication and designed the concept over 15 times, considering windspeeds, hanging hazards (including the building’s façade), and unpredictable weather.
Getting materials and equipment to the jobsite also required creative problem-solving. The only way to transport necessary components was through an 8ft-deep freight elevator. Once on the top level, we hooked each piece onto a trolley beam, wheeled it out of the freight and lowered it into place. To move the MER without disturbing tenants, the team cut a hole in the roof and built a temporary, waterproofed structure over it. Then they installed a chain fall hoist and lifted the equipment to the roof.
Though the MER migration went smoothly, putting a hole in the roof triggered a series of unforeseen air pressure-related issues known as the stack effect that can disrupt the way elevators operate. To combat this, we cordoned off areas with temporary walls and opened the windows on select floors to relieve the pressure.
Finally, matching the new façade to the original was a concern from day one. The stone used for 520 Madison was sourced from an open-pit quarry that shut down years ago. We connected with the owners, who found stones from 37 years ago. The slabs were shipped to New York to see if they matched the existing façade. As it turns out, those blocks were part of the batch quarried for the original 1981 exterior.
520 Madison Avenue New York, NY
AMA Consulting Engineers
Active Design Group Engineering