The Sapphire Gallery is a residential addition designed to display a private collection of contemporary art while also providing for a home office with views to the surrounding hills.The owners’ collection includes work by the artists Gregory Crewdson, Uta Barth, Tomoroy Dodge and the video artist Jennifer Steinkamp, and they wanted a new building that would be more than just a container for their art collection. The new gallery extension is multivalent, with different spaces for presenting artworks, while also opening to hillside views, incorporating a home office, and creating a compelling new focal point for the approach and entry to the property.The new structure is grafted onto the circulation spine of the existing house and lifted off the ground to provide a minimal footprint. Freeing the ground plane creates a new hardscape/landscape area for the family that they use as carport, children's play area, for art parties and video projections.A structural system of lightweight braced frames was developed to achieve the double cantilevers at each end of the trapezoidal building, which were factory built and assembled by crane in one day. These trusses rest upon moment frames that clear span the open ground plane in the perpendicular direction, allowing the floor and roof diaphragms to be framed conventionally. The system proved to be a remarkably simple, flexible and cost-effective way to achieve the program parameters of the project.The remaining details of dark quartz pebble flooring, white steel stairs and perforated steel railings, full height pivot doors, and walls of UV treated glass are designed as a quiet backdrop to the artworks and natural surroundings. An array of photovoltaic cells on the South facing sloped roof produces an average of 15kWh per day, enough to supply all the energy for the new building with a surplus directed towards the main house.