Not far from the Bois de Vincennes on the eastern side of Paris, a somewhat dated 484-square-foot apartment was waiting to be reborn as an inviting duplex.Its owners, a young couple, had bought ...

"Some people think of an ADU as a tricked-out garage but it's a house with a garage underneath — a two-story home — just small." Building one similar in size to Iverson's costs about $250,000.

When Korean architect Hyun-Wook Lee adopted a simple duplex design that he had learned in Vancouver, and gave it the novel name of “peanut house,” he changed more than the way Koreans build homes.