At Escala, a condominium project in Seattle, a quarter of the 270 units have double master bedrooms, said John Midby, a partner in the development. In St. Louis County, Dennis Hayden, president of Hayden Homes, said that each of the 30 detached homes in his latest planned community would have two separate-but-equal bedroom suites.

Kristen Scott, an architect in Seattle, said about one-third of her empty nester clients asked for separate bedrooms, which can cost a few thousand dollars to more than $100,000. In Honolulu, Nancy Peacock, an architect, said her clients increasingly requested “punees,” as daybeds are known in Hawaii — sometimes on the lanai, the covered porch of the house.

In St. Louis, Carol Wall, president of Mitchell Wall Architects, said that three or four years ago her company began “doing a lot of these little rooms off the master bedroom where the snorer would go.” More recently, couples, including some in their 30s, have started asking for two master suites, “and we don’t ask any questions,” Ms. Wall said.

Not everyone wants to talk about it. Many architects and designers say their clients believe there is still a stigma to sleeping separately. Some developers say it is a delicate issue and call the other bedroom a “flex suite” for when the in-laws visit or the children come home from college. Charles Brandt, an interior designer in St. Louis, said, “The builder knows, the architect knows, the cabinet maker knows, but it’s not something they like to advertise because right away people will think something is wrong” with the marriage.

Image Credit... Dilip Vishwanat for The New York Times

An interior designer in Chicago moved into her son’s bedroom when he went off to college. “Separate bedrooms are de rigueur for us,” she said, adding that she and her husband sleep together on the weekends. The couple asked that their names not be published.

Fred Tobin, a builder in North Canton, Ohio, is friends of a prominent couple in Columbus whose house was remodeled with two master bedrooms. The wife sleeps on one side of the house, the husband on the other. “It’s a hush-hush thing,” Mr. Tobin said. “The husband travels a lot, all the time, and he comes home late, and he wants to be able to check his e-mail and go to bed without waking her up.”