300 New Jersey Avenue

300 New Jersey Avenue is a state-of-the-art office building in Washington, D.C., located just one block from the U.S. Capitol. The project includes the construction of a new centerpiece atrium that connects two existing office buildings and is the first office building by London-based Rogers Stirk Harbour + Partners and Pritzker Prize winning Principal Richard Rogers.

Enclos was responsible for the challenging facade program that encloses the new 10-story atrium space. A yellow tree-like AESS steel construct provides the atrium’s vertical structure, supporting a trapezoidal flying glass roof in addition to carrying exposed HVAC and other building system components. Multiple levels of sky bridges tie the complex together. With all structure and systems being exposed, the highest level of craftsmanship was required for every aspect of the project.

Enclos put its supply chain to work early in the project, with glass coming from Minnesota, aluminum framing fabricated in New York, and steel in New Jersey. Aluminum units were glazed and assembled in a Pennsylvania shop to maximize workmanship in a controlled environment. The glass units were then transported by “wide-load” trucks, escorted near the jobsite and offloaded for just-in-time delivery to accommodate tight construction staging.

Facade construction consisted of a top-down placement process, with 12.6´ x 4´ horizontal glass module skylight sections being set by a tower crane. A hydraulic crane was used to install 12´ x 6´ vertical glass modules, with the wall held in place by steel rods attached to the surrounding buildings. A series of spring assemblies are under constant pressure and transfer tension into vertical rods for dead load. Lateral loads are transferred onto the horizontal rod-truss and the existing historic structure via compression spring anchors. The structure is designed to have the capacity and integrity to flex up to three inches in any direction to compensate for thermal expansion and wind forces.

Clark Construction — with 40 subcontractors and an average of 200 site workers each day — constructed the project over a three-year period. Space was extremely limited on the dense urban site, and the office buildings immediately adjacent to the site were operational throughout construction. An Enclos project management and site operations team worked closely with Clark and other subcontractors to assure optimum site logistics.

300 New Jersey Avenue is LEED Gold certified by the U.S. Green Building Council. The project’s sustainable features include a green roof and water treatment from the atrium in the existing building’s storm-water processing system.



Facade Area:

12,000 sq ft


Washington, DC




112 ft


Dweck Properties

General Contractor:

Clark Construction Group


HKS, Rogers Stirk Harbour + Partners

Facade Consultant:

Curtainwall Design Consulting


Best of 2009 - Best Office Building
Mid-Atlantic Construction Magazine, 2009

Washington Contractor Award - New Construction
WBC Craftsmanship Awards, 2009

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