425 Park Avenue, New York

425 Park Avenue is new 687-foot tall tower in New York located between 55th and 56th Streets in Midtown. It is the first new skyscraper built on Park Avenue in the past 50 years to be dedicated solely to office space.


  • New York, NY, USA


  • L & L Holding Company, LLC

Project Status

  • Completed in 2017


Flexible Structure and Systems for New York’s First WELL-certified Office Building

The tower replaces a 32-storey 1950s building while retaining 25 per cent of the existing structure at its base. The world-class office building will provide sustainable office space over three gradated tiers: a seven-storey base, a recessed central section, and a high-rise section which will house premium offices. Each of the floors is column-free thanks to cantilevered framing, thereby maximising open space, views and flexibility.

The structural system we designed consists of long span composite steel framing to support the floors and a concrete core that provides lateral load resistance. The core has been placed at the rear of the building to maximise views to the front over Central Park. 

MEP systems designed to provide control and flexibility

An important focus has been on providing open and public spaces for the occupants, including a triple-height atrium at the base that will function as a public gathering space, and a large plaza with the potential to house large-scale works of art. Set back at the second level, a seasonal sky garden and amenity terrace will boast impressive views over Central Park and the city. An additional terrace and triple-height sky lobby will be in the top section.

The tower will be New York City’s first WELL-certified office building and it will include a meditation centre, green roofs, air filtration, advanced water purification, an abundance of natural sunlight, a dedicated wellness centre, and common space to encourage creativity and collaboration. The project is also pursuing LEED Gold certification.

The building uses high efficiency water cooled DX units with free cooling coils. This system enables each individual tenant to have full control over the operation and costs of their system. The system was designed with sufficient capacity to serve the requirements of demanding tenants, such as those involved in the financial services industry.

The project was designed in BIM which enabled detailed coordination between the structure and MEP services. The cantilevers created column-free space but required very deep structural elements causing difficult coordination conditions which were resolved in BIM.

All these features combine to create a building that meets today’s requirements while providing enough flexibility to allow for future adaptations.