New York, New York

One Wall Street

2021 Engineering Excellence Awards – Gold Award, Special Projects – American Council of Engineering Companies New York (ACEC NY) | 2024 Excellence in Concrete Construction Awards, Repair & Restoration – 2nd Place – American Concrete Institute (ACI) | 2024 Repositioning Award — Award of Excellence – Council on Tall Buildings and Urban Habitat (CTBUH) | 2025 Innovation in Residential Award - Commercial Observer Breakthrough Awards | 

The repositioning of One Wall Street represents one of NYC’s largest office-to-condominium conversions, transforming 30 office floors into 566 residential units, expanding lower floors for modern retail space, adding six floors—including a rooftop pool—to the south tower, and breathing new life into the iconic building.

To achieve the desired six-floor vertical addition atop the south tower with the existing structure, we specified sustainable lightweight voided concrete slabs, which reduced the need to reinforce existing columns while still achieving the desired floor heights.

DeSimone’s structural interventions to this landmarked building carefully preserved its historic aesthetic while reconfiguring the steel structure as required to convert floors for residential use.

ClientMacklowe Properties
Architect:SLCE Architects
Size30 Stories | 1,600,000 SF (148,644 SM) | 566 Units
SustainabilityLEED Silver
Office:New York
Completion:2022

We created double-height retail space by removing the existing third-floor concrete slab and adding a steel truss that transferred the lateral loads to a new shear wall system.

For the ground-floor retail atrium, we removed a single existing column supporting 26 floors above and devised a system to transfer the load to new supports. That required hydraulic jacking techniques to preload girders and prevent deflections during construction before building permanent structures.