Principal Jim Zack had an idea when he first saw a small cottage in the Noe Valley neighborhood of San Francisco. The old cottage was situated on the far end of a 25-by-100 foot lot, and Zack knew the space would allow for two units. So, alongside Lise de Vito, the other principal of Zack | de Vito Architecture + Construction, the firm renovated the cottage and built a complementary second property. “We wanted to explore the idea of living small: how to put two detached houses on a lot that typically has one building,” Zack says. But “living small” doesn’t mean feeling cramped, even when seven people share the space. Both owners work for start-ups – the front unit has two children and the back has two musicians – and their homes open to a courtyard. And just like the lot it sits on, the architects made sure that certain rooms could be used in a variety of ways.