Tasked with transforming a 93-square-foot brick San Francisco boiler room, built in 1916, into a guesthouse, architect and metalworker Christi Azevedo flexed her creative muscle. The three levels of the house transition from public to private: The ground floor is composed of the kitchen and living-dining area; the bathroom and closet occupy the mezzanine, accessed by a ship’s ladder; and the sleeping loft hovers a couple steps above. The seminal 1970s tome A Pattern Language, written by Christopher Alexander, Sara Ishikawa, and Murray Silverstein, inspired the layout. Photo by Cesar Rubio. Photo by Cesar Rubio.