For 11 years, Mara Lipner and Gabrielle and David Chamberlain shared a summer rental on Shelter Island, the verdant knob that sits in a bay between the North and South Forks of Long Island’s East End. The trio grew to be close friends, meeting up most weekends throughout the summers to enjoy the house and its water views from its vantage point in Shelter Island Heights. The only problem came in mid-September, when the season ended. The house wasn’t winterized, so year-round visits were not an option.

Mara, who works in financial services and lives in Manhattan’s East Village, and the Chamberlains, executives at experiential design agencies who live in Harlem, eventually looked into buying or building separate weekend retreats that they could enjoy all year. They searched for places on Shelter Island with water views that they could afford. But eventually they realized they could do something more interesting if they pooled their resources.

One day the three of them checked out a cedar-forested two-acre parcel. They broke through shrubbery to find West Neck Creek, one of several bodies of water that notch into Shelter Island, creating long peninsulas. “We got into our respective cars and drove back to the city,” Mara recalls. Chatting en route with each other and the broker, they quickly made up their minds. “By the time we got back,” Mara says, “we had put in an offer.”

The next step was recruiting Corey Yurkovich, a New York designer they knew socially. By this point they had decided on a single house that the three would share. It would preserve the convivial setup they had enjoyed and be more economical than two autonomous dwellings. Also, the construction would be easier for three busy professionals to oversee. “It worked out that we could tag team when someone had to be on the phone with the contractor or make a day trip to the island,” Gabi says.

They were clear about the architectural style, opting to echo old barns. Gabi says the building type appealed to David because of “his more rural upbringing” in southern England and to Mara because she’s “a hip person who appreciates good design.” Gabi herself was favorably reminded of the “black, clean silhouettes of abandoned tobacco barns” in Kentucky, where she often has to travel for work.

The design evolved into four structures connected by a glass hallway in a not-quite-straight line. The volumes at either end are book-matched two-story buildings, one for Mara and the other for the Chamberlains. Each has a private entrance, bedroom, and living room downstairs, and an individual staircase leading to two more bedrooms, including the master, upstairs.

Between the private volumes are two single-story communal structures. One has a combined kitchen and dining room. The other houses a living room, pantry, and powder room. Sliding doors in both of the smaller buildings lead to paved outdoor seating areas overlooking the water. From the water—say, on a paddleboard—the house looks like a charming silhouette cut out of construction paper.

The friends have customized their connected-yet-separate domiciles. The Chamberlains’ side reflects a trained eye for contemporary design and an emphasis on hospitality. Mara has furnished her end with Nakashima heirlooms inherited from her family. This wing is also populated with toys belonging to her four-year-old son, Barrett. (Let it be known and admired that Mara gave birth six weeks after the new homeowners received their certificate of occupancy. She soon discovered that the distance between the private quarters came in handy when she was up at night with a crying baby.)

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Four years into this social experiment, family members on both sides stake out the extra bedrooms, while friends drop by spontaneously for drinks or a meal. Yurkovich, who visits with his wife and kids, says the children love to race up and down the glass hallway, which functions as its own spacious room.

The trio has no intention to sell in the short term, but they have fun imagining future scenarios—in-law setups, caregiver quarters, or maybe another cluster of close friends who like the idea of sharing a roof. “For a family with a couple of teenagers,” Mara says, “it would work really well.”

Project Credits:

Architecture: Office CY / @office.cy

Construction: Fokine Construction

Engineering: Condon Engineering

Landscaping: White Oak Farm and Gardens

Other: Liberty Landscaping & Binder Pools