The project consists of the adaptive reuse of a 1925 Building in Seattle’s Belltown neighborhood that once housed a charter school and offices. The original building was 20,565 square foot building was gutted to its bare structure and underwent a full seismic retrofit along with adding a 4th floor penthouse to the existing three-story building. A four-story board formed cast-in-place concrete stairwell and elevator shaft was a key element to the building tying into the existing century old concrete walls exposed during demolition. Custom made lighting was also installed on the stair while the entire shaft is capped with a skylight to allow daylight down through the building. Among the many challenges working within the building was the construction of the 4th floor penthouse. The design team engineered a system of short columns set on top of the existing grid of columns that extended up through the sloped roof structure. This new grid of columns was infilled with beams and trusses to create a level floor structure to build the new addition. The new interstitial space allowed for the MEP team to perform all their rough-in within the void providing for a clean exposed open-to-structure ceiling in the 3rd floor office space.