While the Heurtleys owned the home it underwent three major changes. They added screens to the windows on the elevated porch as well as a breakfast room on the main floor. The third of the Heurtley's changes converted the "wood room," as it was known on Wright's original drawing into a pantry or food storage area. It is thought that the breakfast room addition and wood room conversion were done through Frank Lloyd Wright's office but the dates remain unconfirmed.
In 1920 the house was purchased by Frank Lloyd Wright's sister, Jane Porter, and her husband, Andrew. They converted the home into a duplex in the 1930s and each floor was separated into apartments. The Porters stayed in the Heurtley House for 26 years. After the Porters left the house, two other owners altered the home further. The kitchens and bathrooms were modernized, the front loggia enclosed and a black iron gate was added to the home's entryway. A master bathroom was added in the last fifteen feet of the main floor veranda and the living room inglenook and dining room breakfront were removed. A second chimney and a furnace were also added. Between 1997 and 2002, the owners of the house spent 1.2 million dollars on a complete restoration of the building.
The Heurtley House is one of Wright's earliest, fully mature Prairie style houses and the patterns that he established with the home would eventually appear in many of his greatest works within the style. The fundamental characteristic of Prairie style are all present in the 1902 Heurtley House. The major spaces are raised above the surrounding grounds, ceilings echo roof forms and the fireplaces are in the center of the house. The exterior features overhanging eaves, a large central chimney, horizontally grouped windows and terraces and balconies. The home's interior is unique in that its ground plan is reversed from the traditional layout of American homes. The living and dining areas are on the top floor of the house.
^Most sources consider the Frank W. Thomas House in Oak Park to be the first fully mature Wright-designed Prairie style house. See The Vision of Frank Lloyd Wright by Thomas Heinz or Frank Lloyd Wright's Chicago by Thomas O'Gorman.