In the summer of 2007, Charlie and Rebecca Fisher noticed something odd about their weekend house, a boxy 1960s cottage in Amagansett, Long Island: “When the washer was on the spin cycle, the whole place would shake,” says Rebecca. That’s when they knew they couldn’t put it off any longer. It was time to renovate.

The Manhattan-based Canadian couple had bought the house three years earlier, drawn to its space-efficient, family-friendly layout (four bedrooms and two bathrooms in 1,200 square feet) and its location 60 steps from one of the loveliest beaches in the Hamptons. Over the years, they’d rented various share houses in the Dunes, as the neighborhood is called, and they remember admiring this one on their evening walks. “There was a big juniper pine and maple out front,” says Rebecca. “It looked like a really happy place.” One spring, the home became available to rent, and they booked it. A month into their stay, a real estate agent called: The owner wanted to sell the house. Were they interested?

The couple decided to go for it. The house was small and scruffy, and the seller was motivated, so they snagged it for $15,000 below the asking price; they paid an extra $1,500 to buy it as-is and furnished, complete with sagging beds in the kids’ rooms, board games in the closet, and a fully stocked kitchen. The Fishers and their three children loved the laid-back vibe of the place (“We come in Friday night, take off our shoes, and don’t put them on again till Sunday—it’s that kind of mood here,” says Charlie) and the luxury of having the beach so close it felt like an appended backyard. It soon became apparent, though, that the uninsulated wooden structure “was starting to come to the end of its useful life,” as Charlie puts it. “It was turning into cheesecloth—you could hear and feel the wind whistling through all the gaps and cracks and crevices.”

They didn’t picture an extensive renovation. “We just didn’t want it to fall down on us,” says Rebecca. Intimidated by the idea of working with an architect (“I don’t know how to talk to them, don’t have the vocabulary, and I thought they might laugh at our budget,” says Charlie), they turned to dwell.com and looked through some of the architects on the site. Two or three clicks in, they found Page Goolrick.

“Her projects looked exactly like our style—lots of light, lots of bookshelves—decorated the way we envisioned our house,” says Charlie. “It also struck me that she said she loves the efficiency of sailboats and likes working with small spaces.” An initial phone call put him at ease. “I had the notion an architect would want to make the thing theirs—so you could tell it was her house. But Page was pleased we wanted to retain the character of the existing building.”

To the Fishers’ surprise, Goolrick’s design process started not with grand architectural moves but with a slew of specific nuanced questions. Where does Rebecca put her bag when she gets in? Do your kids sit down to put on their shoes? When you have people over, do you barbecue? Where do you like to curl up with a good book? Goolrick explains: “To solve design problems, you have to look at how a family really lives and works. I think an architect’s job is to celebrate what people really care about and simplify and streamline the rest.”

To that end, Goolrick embraced the particular challenges of oceanside living and selected materialsthat “just evolve and soften over time, like driftwood,” and require little maintenance. She essentially rebuilt the house using dry construction methods, foregoing inflexible, crack-prone materials like plaster, Sheetrock, and Spackle in favor of those (like wood) that can expand and contract.

The exterior, once flecked with peeling paint, is now clad in cedar plywood paneling scored with a router every eight to ten inches, so you can’t tell where the standard four-by-eight sheets begin and end. Only four things in the house are painted: small areas in the bathrooms, the bright blue front door (a color Charlie first spied on an old Land Rover Defender and had Benjamin Moore custom-match), the bookshelf in the living room, and three blue-gray sliding panels in the kitchen. Everything else—the floors, walls, and newly exposed ceiling rafters—is stained or oiled wood. Anticipating the weathering effects of the salty sea air, Goolrick intentionally selected matte stainless steel hardware: “When you work in a context like this, you know all the metal will lose its sheen anyway—things tend to get rough. So I started with something that was soft and brushed in appearance.”

Goolrick’s experience with boats—she races sailboats and owns one—combined with living in Manhattan has made her something of a small-space guru. “After you live in New York City for a while, you learn to measure very carefully and find space,” she says. Limited by strict setback rules, she squeezed every buildable inch out of the site, enclosing an existing carport and bumping out the walls under the eaves to increase the footprint by just 157 square feet. “It’s the perfect diagram of how you use land well,” she observes.

On a tour of the house, Goolrick takes pains to point out how every millimeter is held to account. To maximize the limited square footage, there are few swinging doors in the house; instead, each bedroom has a pocket door that slides into the wall. In lieu of lower cabinets in the bathrooms and kitchen, Goolrick installed drawers, which increased the storage space. “Storage functions better that way—rather than opening doors and crawling in to look. That’s the sort of thing you’d definitely do in a boat. You’d never waste that space.”

There are several spots where space is “borrowed” from an adjoining room—where a build-out in one room creates a recessed storage nook on the other side of the wall. A tiled shower seat in the master bath, for example, translates into an inset bookshelf in Emily and Henry’s room. The dialed-in detailing continues in the hallway, where shelves are narrower at the top and deeper at the bottom to accommodate board games and oversize kids’ books.

To make the place feel bigger, Goolrick employed some architectural tricks. She established what’s called a “datum line”: a consistent horizontal point—in this case, at six feet eight inches—that almost everything in the room hits, from the top of the windows to the top of the range hood. “You establish order by height,” explains Goolrick. “If I could force the fridge to be that height I would!” She also stained the floors a soft gray that matches the deck, so the outdoor area feels and looks like an extension of the living room, visually doubling the space.

Today, little of the original house remains, save for the number of bedrooms and bathrooms, the brick chimney, and a few token items transferred in the purchase, including a coffee table, a set of red plastic tumblers, and a framed map of Long Island.

The house may have undergone a structural and interior makeover, but its mellow spirit, as well as its exterior appearance, has been respectfully maintained. While the house was under construction, “neighbors would walk by and say, ‘You’ve been working on that for a long time and it looks exactly the same,’” recalls Charlie. “And we’d say, ‘Thank you.’ We’re not the kinds of people who use words like ‘karma’ or ‘feng shui,’ but something about the place has always felt right for us. As soon as our feet hit the sand out front, everybody just chills.”