1785 Massachusetts Ave NW, DC, Grunley Construction Co Inc

The scope of this 1915 National Historic Landmark included installing pile caps, footings, columns, walls, new slab on grade and framed deck inside and beneath an existing seven-story building, working in and around mini piles supporting the structure. This scope included building two new structural levels beneath the existing building. Other additions: a seven-story concrete elevator shaft in the building core, requiring numerous infills and toppings to reconfigure existing floors; two large mechanical/utility vaults, retaining walls and footings. Unique features of this project include a raised acoustical slab and “super” lightweight concrete fill used to minimize the dead load of existing floors.