This 1000sf addition to a mid-century modern 712sf home was placed below the existing house to minimize building footprint and the impact on neighbors’ San Francisco Bay views. The project was designed for a young family with an open floor plan concept and decks on each level to allow for easy access to the outdoors. Beams, hardware and concrete retaining walls are exposed throughout. Sustainability was primary consideration with cool roof, salvaged lumber, natural daylighting and no-VOC paints throughout.