Clients are sometimes surprised when home builder and designer Marnie Oursler starts talking about bedroom doors.

They expect to discuss things like windows, wall colors and where a built-in bookcase might fit best. But many of Oursler’s clients hadn’t considered that creatively designed interior doors can add personality, improve the flow of natural light, and also serve as flexible partitions to break up an open floor plan or connect two rooms.

“I’ve been using doors to add character in houses for a long time,” says Delaware-based Oursler, who hosts “Big Beach Builds” on the DIY Network. “Mixing up doors throughout the house is really important,” she says, “and it’s easy.”