100 California: Building on 60 years of Swinerton History

In 1958, Bethlehem Steel Corporation selected Swinerton & Walberg to build their state-of-the-art West Coast headquarters at 100 California Street in San Francisco. As one of the nation’s largest shipbuilders in a boom time after World War II, Bethlehem tasked Swinerton & Walberg with building this showcase structure made from Bethlehem’s own steel.

Fast forward nearly 60 years and Swinerton is building on this historic legacy for current owner Pembroke Real Estate.

In an effort to generate renewed appeal in an ever-competitive commercial leasing market, Pembroke Real Estate set out to revitalize the 2,600 square foot lobby of the historic building. This project presented significant challenges due to its location in the densely populated Financial District in downtown San Francisco, as well as the high volume of foot traffic that passed through the lobby every day. Swinerton’s San Francisco Special Projects team expertly tackled the complexities of the project over the course of four months. The team built a tunnel to provide tenants a safe travel path through the lobby with a platform above to complete work; scheduled and coordinated subcontractors with use of very limited staging space; completed select components of the project at night; and procured materials well in advance.

The plan for the building was to enclose the current roof on the 14th floor to prepare it for tenant occupancy, adding an additional 16,080 square feet of leasable space. This roof area housed the air handling system and cooling tower. To add the leasable space while keeping the building fully functional, the team planned to add a 15th floor roof deck that would house the new mechanical equipment. Because of the dense, urban location, space constraints required a highly detailed phasing plan, which included demolition and abatement work. Instead of a typical procurement process, Swinerton purchased equipment and materials well in advance and planned two separate time-constrained crane picks to bring all materials on site.


Built In


Renovated In


Sq Ft Added

In October 2016, a temporary tower crane was placed on Davis Street for the first of the two crane picks. Measuring 220 feet tall with a 130-foot jib, the crane brought up the new air handler system, cooling tower, metal decking, steel, rebar, and concrete over the course of a three-week period. This enabled the team to infill the building, place the cooling tower and air handling units in their new home, and bring them online prior to the next crane pick. The project’s second crane pick was in January 2017, and included structural beams, additional metal decking, rebar, and concrete.

Layering additional floors on top of a building added complexity to the project. By building out an entire leasable floor, adequate accessibility for future tenants was required. Of the six elevators in the building, two were to be raised up one floor, which required seismic retrofitting to the entire system and sophisticated scheduling and coordination.

The job was completed in the summer of 2017—almost 60 years after Swinerton first set foot at 100 California street—and looks forward to opportunities to further revitalize the historic building constructed by their forebearers.

100 California: Then and Now