After years of renting a modernist Martha’s Vineyard summer house by famed Harvard Five member Eliot Noyes, Kathy and Jerry Kauff wanted a place of their own, one that would be both a pleasurable à deux retreat and a kids-and-grandkids magnet. So when a rare four-and-a-half-acre property with magnificent sunset views across Menemsha Pond became available, the Kauffs jumped at the opportunity.

“They’re very athletic, very outdoorsy,” says architect Toshiko Mori, yet the Kauffs wanted to be able to live entirely on the ground floor if time’s march made stairs a burden. At the same time, says Kathy, “we didn’t have the means to build a 5,000-square-foot trophy home.” Mori’s smart design obliged them with a structure that’s half that size but feels like two interleaved residences: a loftlike ground floor with kitchen, living room, and master suite and a second story containing four bedrooms and two baths. To make the upstairs feel more spacious, Mori created an unusual inverted hip roof that, without contravening the Vineyard township’s strict, tradition-based building code, elevates the ceilings at the edges rather than the middle, opening the snug rooms to sunshine, sea breezes, and panoramic vistas.

Simple materials like prefinished bamboo flooring and off-the-shelf items like a prefab fireplace kept costs low, as did Mori’s refusal to start building until every design issue was resolved. The latter tactic also produced a home that, in every particular, functions as planned. “Toshiko paid attention to how we live and made it work so nicely,” Kathy says. “We benefited from her discipline.”