In Eastham, behind a beautiful home overlooking the sea, a little path leads to a charming cottage. It’s reminiscent of the line in a poem by Lydia Marie Child, ‘Over the river and through the woods, to grandmother’s house we go’ and indeed, perhaps one day the homeowner’s grandchildren will sing the tune as they traverse from her cottage to her waterfront house for a visit. 

The homeowner had long dreamed of building a guest house for her sons and their future families to enjoy. When the adjoining lot went on sale, she leapt at the opportunity. “I’d walked by that property a million times,” she says. “It was a tiny little thing. I didn’t realize how run down it was—it was collapsing around itself.” 

The homeowner enlisted the help of architect Peter Haig, principal at Architectural Design, Inc. in Orleans, to transform the dilapidated structure, which was perched on only a quarter acre and faced significant design constraints due to setback requirements. The new home would be tiny—but Haig was undaunted. His design blends the boundary between inside and outside to help the home feel spacious despite its size. Its coastal location was heavily incorporated from the start. “One of the primary concepts in my architectural training was the importance of context—where you are matters.”

Standing in the entryway, summer seeps in from every direction. Daylight streams down from windows in the stairwell, illuminating the sand-colored wood and paneled walls, while a warm breeze flutters through the open Dutch door. A line of trees is visible beyond the deck—a purposeful design choice grounding the home in its...