Measuring 385 ft tall, the 1812 North Moore office building is one of the tallest buildings in the Washington, D.C., metro area. Capped by a distinctive steel-and-glass pyramid, the 30-story building provides 600,000 column-free sq ft of office space designed to LEED Core and Shell-Platinum certification standards. The building, which includes five below-grade levels, comprises structural steel and cast-in-place concrete.

To erect the structure, cast-in-place subcontractor Clark Concrete was charged with completing concrete pours over an 87-week period. To perform its contracting responsibilities and keep the project progressing smoothly, the company, a subsidiary of Clark Construction Group, had to maintain a close working relationship with the structural-steel contractor.

Collaboration proved particularly crucial in the construction of the building's north side, which cantilevers over the substation beginning at Level 11. Full-height structural-steel girders supported by 10,000-psi concrete columns support the cantilever from its starting point at Level 11 to the top of the structure, at Level 35. The girders also support two levels of hanging structural steel and slab-on-metal deck, which required the cast-in-place concrete contractor to work around ironworkers as they completed their welds.

Installing 1812 North Moore's signature translucent pyramid also required intense coordination due to the introduction of a bonded, post-tensioned system into the concrete slabs at Level 34, where the building's concrete begins interfacing with the pyramid's steel. To prepare for this, the team cast anchor bolts into the top of the Level 33 concrete columns while structural-steel members were set and encased in concrete. These members had base plates welded to them that support the shoe-and-pin connections for the structural steel trusses. At this level, the structure's perimeter columns become "cranked" and begin to follow the slope of the pyramid's facade.

The building's exterior comprises a curtain-wall skin, metal finishes and a black-granite base. Floor-to-ceiling perimeter glass provides natural light to every floor.

In addition to achieving LEED Core and Shell-Platinum status, the Rosslyn, Va., office building, which was built as a speculative development, also earned LEED Neighborhood Development Gold certification, making it one of the largest commercial green buildings in the state of Virginia.

The project also includes an advanced building energy-management system, low-VOC finishes, energy-efficient lighting and a preference toward regional materials, with a high percentage of recycled content.

1812 North Moore, Rosslyn, Va.

Key Players

Owner Monday Properties

Design Firm Davis Carter Scott

Contractor Clark Concrete (Clark Construction Group)

Structural Engineer KCE Structural Engineer

Civil Engineer VIKA

MEP Engineer TOLK Inc.

Subcontractors Vstructural; Harris Rebar; Vulcan Materials Co.; East Regional