Designed by Cary Bernstein, this living space design which is called a Potrero House is located in San Francisco, California. This living space project is involved the expansion, interior renovation and furnishing of an old cottage on a triple-wide lot in San Francisco. The connection to the outdoors and the contemporary materials with the endearing and quickly characteristic of the original building such as its mid-ot siting, irregular footprint and the rough-sawn paneling. An opportunity to reduce the energy consumption and employ the sustainable materials is provides by the third floor expansion. The natural daylight and the ventilation are increased by the introduction of operable, high-performance wood windows and the open vertical core of the central stair, while it is reclaimed the wood floor from a 19th century barn add a warm patina which is consistent with the original cottage.