455 Eye Street
Project Location
Washington, DC
Awards
Outstanding Project Award – New Construction $25M-$75M: SEA – MW
Project Type
– Mixed Use/ Multi-Family Residential;
– Renovations/ Adaptive Re-use;
– Repair/ Restoration
Services
– New Construction;
– Renovation;
– Repair and Restoration
The Project
An 11-story mixed-use residential building constructed above, through, and adjacent to an historic two-story, commercial building and two attached historic four-story row houses. The top ten levels are residential apartments with a rooftop terrace and pool at the penthouse level. Part of the ground level is dedicated to retail with the rest as residential lobby and amenity spaces. The 4-story below grade parking structure is immediately adjacent to the existing historic buildings
The Challenge
There were issues stemming from the requirement to retain and re-use portions of the existing historic buildings and to construct above and adjacent to these structures.
The Solution
The east side of the residential tower is constructed above the historic commercial building. To support the new construction, the concrete columns were extended through the existing structure and supported on micropile foundations installed within the existing structure. The roof of the existing structure was removed (except for the blacksmith shop, the oldest portion of the five historic structures) and the exterior walls were re-attached to the new 4th floor. Since the new columns interrupted existing 2nd floor structure, the existing structure was re-supported on the concrete columns using large haunches.
The wood structure of the historic row houses was in poor condition. The floor and roof structures were largely rebuilt from new framing, re-using the old joist pockets where possible. The masonry walls were re-pointed in places and completely re-built in others.
Since much of the site was occupied by existing structures, the footprint of the parking levels was constrained. The remaining portion of the site was excavated four stories below grade for parking. To excavate adjacent to the existing buildings, a combined underpinning system and support-of-excavation system was conceived using micropiles, top-down underpinning pits, and wood lagging. Once the excavation was complete, continuous concrete basement walls were constructed inside this combined system.
