Touring NYC’s 425 Park Avenue Transformation

(Photos: AISC)

AISC Structural Steel Specialists, Jacinda Collins (NYC market) and David Fennell (Seattle market) toured the construction site of 425 Park Avenue in New York City’s Midtown Manhattan this week. The steel-framed skyscraper will rise to 47 stories with a height of around 900 ft and is the first office tower to be developed on Park Avenue in 50 years. The project is expected to be completed at the end of next year.

The tower replaces a 32-story 1950s building while retaining 25% of the existing structure at its base. By reconstructing a new building on top of the existing structure, the owner was able to create 90,000 sq. ft of additional space. The new building will provide sustainable office space over three gradated tiers: a seven-story base, where the framing of every other floor was removed to create a three-story lobby and double the height levels up to the new 7th floor (previously the 13th level of the original building), a recessed central section and a high-rise section that will house premium offices.

Each of the floors are column-free thanks to cantilevered steel framing, thereby maximizing open space, views and flexibility. The sloped "V" and tripod columns at the diagrid floor (7th Floor) and club level (16th Floor) have a 7% twist to accommodate the façade. The skyscraper’s structural system consists of long span composite steel framing to support the floors and a hybrid core with embedded steel columns to transfer the loads and aid in constructability.

Owen Steel (an AISC member and certified fabricator) is the project’s steel fabricator; Foster + Partners is the architect; WSP is the structural engineer; and AECOM Tishman is the general contractor.  

For more about the project, visit You can view additional photos from the construction site tour on AISC’s Facebook page ( in the 425 Park Avenue construction site tour photo album.