1789 Massachusetts Avenue

The landmark building was also used as offices during the mid-20th century. In 2013, the American Enterprise Institute for Public Policy Research (AEI) purchased the building with the intent to infill its existing courtyard and add a second, lower-level basement. The renovation needed to balance these goals with interior and exterior easements designed to protect the landmark.

TYLin provided structural design of the vertical addition and full footprint below-grade addition of a basement level for the five-story building’s complete interior renovation. The design required that TYLin maintain a high level of sensitivity to the historic integrity of the facade and other non-structural elements while incorporating heavy load transfers and aggressive excavation.

In addition to underpinning the new lower-level basement, TYLin’s designs incorporated strict vibration criteria for sound and camera studios to be located on the upper basement suspended slab. A partial footprint penthouse was added to the top of the building, creating rooftop assembly space and views of the historic neighborhood.

New framing was incorporated with the existing structure to create a 70 foot long steel truss. Placed between the second and third floors, the truss removed columns between the first and second floors, creating an auditorium space. Deflection was strictly controlled to protect historic finishes and minimize floor slope.