The dunes of Truro, Mass., at the outer reaches of Cape Cod, are a place of great natural power. But wind, wave, and tide aren’t the only forces that clash along this shore. The beauty of the place and its proximity to Boston and New York routinely pit big-foot homeowners in competition for property, views, and shore access. Boston-based architect William Ruhl is all too familiar with the spectacles that ensue, but he and his clients are generally able to stay out of the fray. “The people who tend to hire us don’t want a big, loud, ego-driven house,” he says, but rather, “something a little quieter that works with the landscape.” This unbuilt vacation house takes that approach to a sublime extreme, nestling into the dune as if tucking itself into bed and pulling up the covers.

If ever a location called for such subtlety in a building, it would be this one. Just downhill from the painter Edward Hopper’s home and studio—and in view of that iconic, shingle-clad structure—the site arouses fiercely protective feelings in those who know it. To minimize the new structure’s visual impact, Ruhl suggested preserving an existing 1820s house on the inland portion of the property. “Our strategy was to turn that into the guest house and stop all the cars there,” he says. “You would walk to the new house,” which would sleep just the owners and a visiting grandchild. “It would be as small and unobtrusive as possible, and built into the dune,” Ruhl says. “It would really defer to the Hopper house and the landscape.”

As designed, the building consists primarily of a concrete “bar,” dug into the dune and projecting out toward the shore, containing a central courtyard flanked by a pair of compact bedroom suites. “It would have a grass roof,” Ruhl says, “so the sand and native grasses would continue over the building.” Approaching the courtyard entry, he continues, “you’d see a retaining wall and grass roof that would match the native plantings around it ... and then a very small glass box.” The latter volume, perched atop the concrete bar, locates the house’s daytime functions within a 360-degree panorama of ocean, beach, dune, and sky. “It’s only 16 feet by 30 feet,” Ruhl says. “It’s big enough for a seating area, a dining area, and a small kitchen—just enough for the grandparents and a child.”

While radical in its simplicity, the plan is eminently feasible, Ruhl says. “The house is only 16 feet wide, so it’s a simple, easy-to-build dimension downstairs.” The upper level’s light steel structural frame incorporates diagonal cables to resist racking forces. “It was meant to feel almost like a boat floating on the water,” Ruhl says. The judges experienced some of that sensation just imagining themselves there. “It’s very evocative of its place,” one said, “extremely subtle and respectful of the land. If it does get built, it has the potential to be a classic house, something that people will talk about and remember.”

On Site The design juxtaposes a solid concrete base with a light, transparent pavilion above. Heightening the contrast is the pavilion’s ultra-attenuated roof, a winglike steel framework clad with copper on top and driftwood-gray wood paneling below.