1129 20th Street, NW Vertical Building Expansion

Location: Washington, DC

Photography © Maxwell MacKenzie

1129 20th Street is located on the East Side of 20th Street between L and M Streets, NW in downtown Washington, DC. The eight-story structure was built in 1968 and had no significant upgrades since its construction. Originally it was about 135,000 gross square feet. Through the use of Transfer Development Rights, the building was increased in height by two floors. Additionally, open courts at three corners of the existing floor plate were filled in at each floor. All together, this increased the existing gross square footage by more than 45,000 square feet.

The new 20th Street façade is a unitized glass and metal curtain wall system. It is a calculated sophistication that allows views out and natural daylight in. The new additions and renovations to 1129 20th Street have breathed new life into an old building. They provide a state-of-the-art work environment that is now competitive with the Washington Class A market. This design will serve as a more timeless expression of the building’s structure, enclosure and internal functions.

This project is LEED® Gold certified.