Project Overview

Berglund provided construction services for the installation of the new Sky Deck Ledge at the Willis Tower. The new glass ledges were installed on the 103rd floor into the curtainwall façade of Chicago’s tallest building. These four pods extend 4 feet 4 inches from the façade and are fully retractable. Offering views down 1,353 feet, each of the pods has five sides hanging from steel trusses that project them outward to create the illusion of walking on air.

Approach

Not one elevator at Willis Tower could transport The Ledge's 1,500-pound tempered glass panels from the loading dock to the 103rd floor of Willis Tower. Each box is constructed of three layers of half-inch thick glass laminated into one seamless unit. So we transported the glass pieces up the freight elevators to the 100th floor. Then we carefully transferred them, placing the panels on top of elevator cars that reached the 103rd floor and unloaded them at the final destination.

Meanwhile, new structural steel was added at the 103rd floor ceiling level to support the glass, and the curtain-wall system was modified using the building's window washing scaffold system. Once the structure was in place, we installed new glass boxes onto a track supported by the new steel. New gaskets were installed to provide a seal around the framing. With this system in place, the boxes were extended and retracted 4 feet 4 inches from the building.

Outcomes

The Ledge introduced a new "wow" factor to the Skydeck experience for millions of Willis Tower visitors. After the project was complete, visitation spiked and tourists lauded the experience. The weightless feeling of standing over South Wacker Drive from 1,353 feet in the air has attracted people from all over the world