An Occupied and Operational Facility

The 640 Fifth Avenue project involved the redevelopment and renovation of an existing 18-story limestone-clad office building, with the challenge of constructing a three-story addition at the top, while remaining occupied and functioning throughout the construction. During preconstruction our team overcame this challenge by blending the best logistical and construction approaches.

One solution was to eliminate the use of a hoist to load materials to the upper floors of the building during the construction phase. Instead, the team used a tower crane that also served to erect the structural steel for the addition. While performing all of this work, the team’s biggest challenge involved their continuous efforts to maintain zero disruptions to the building’s systems, while installing the new MEP systems.

Building Renovations
and New Construction

The team stripped the existing exterior limestone façade from the 18th floor down to the 10th floor, where they erected and maintained a temporary protective roof. Construction consisted of selective terrace and structural demolition along with new structural steel and reinforcement of existing support members from the ninth floor up. The scope included replacing and relocating the mechanical and electrical equipment in a phased sequence, while keeping all existing systems operational for the lower floors.

During the renovation, the project team began to erect the steel structure above the occupied building, adding three new floors. Then floors 10–21 were enclosed in a new, glass and stainless steel curtainwall system. In order to erect the steel and load the building, our team’s approach involved cantilevering a Gantry tower crane out from the base building on a steel platform. While this required reinforcement to the building in certain locations, this approach to construction allowed the completion of each floor during the steel erection.