The John M. Duncan House is a historic residence located south of Winterset, Iowa, United States. Duncan acquired this land from Canada Fink in 1866, and the house was built sometime after that. It is an early example of a vernacular limestone farmhouse. The house is a single-story, one-room structure with a raised basement. The exterior is composed of large rubble stone laid in an uncoursed broken bond that gives it a wave-like appearance. The house was listed on the National Register of Historic Places in 1987.