Patrick Ahearn strolls briskly along School street in Edgartown. A light rain is falling, but he’s not a bit bothered by the soggy weather. The architect cannot walk past more than a couple of houses without passing one that came off his drawing table. On long stretches of some downtown streets, he has been the architect for nearly every building.

The author of a new book, Timeless, to be published in December, Mr. Ahearn points out architectural features as blithely as some would read a grocery list.

He notes surgically inserted Nantucket dormers, the preserved barn that is now a pool cabana with a sleeping loft, floor-to-ceiling doors that disappear when folded back, the Greek Revival playhouse for kids, the space between outbuildings that form an urban Island compound.

Mr. Ahearn said the "greater good" of the community is important to him when designing a home. — Mark Alan Lovewell

Mr. Ahearn grew up in Levittown, N.Y., the nation’s first mass-produced suburban neighborhood, with hundreds of nearly identical small homes. But instead of rebelling at the conformity, the future architect took note of the design features that saved space, created light, and encouraged people to connect with their neighbors.

After graduating from Syracuse University, he settled in Boston, where he earned a reputation for preservation while working on the revival of the Faneuil Hall Marketplace and the historic brownstones in the Back Bay.

His career was well established by 1989, when he tired of his summer home on Cape Cod and bought a project house in Edgartown. Architecture was not on his mind when he visited the Island.

“I came here as a retreat, so for the first five years, I didn’t work here on purpose,” he says.

Eventually he thought there might be an opportunity in Edgartown, with its many grand but deteriorating whaling-era homes. He placed a series of advertisements in the Gazette, a new one each week, to gauge interest in his work.

“I did a little pen and ink sketch of a different house I’d come up with,” he recalls. “That first summer I got 26 projects. I said wait a minute, this is real. I opened up the office, and the rest is kind of history.”

Turning onto Cooke street, the light rain has escalated to a moderate downpour. It seems only to quicken Mr. Ahearn’s pace. He stops at a recently completed project and notes how it illustrates his style of combining opposites, traditional architecture and modernism, preservation and innovation.

“This house lives like a totally modern house,” he says. “It’s a big open floor plan, indoor-outdoor living. This really satisfies the goals and objectives of the marketplace, but also teaches them about preservation of the architecture and scale.”

Maintaining sight lines to the water for neighbors is taken into account. — Mark Alan Lovewell

On South Water street, he pauses at a home that illustrates his “greater good” theory, which guides nearly everything he designs for clients. On this street, the neighbor on the left and the neighbor on the right are also likely to be his clients.

“Most architects are egomaniacs, by the nature of being the creator,” he says. “In my case, I say, look, you need to take into consideration, particularly in a historic district, the context in which you are working. You need to think about not only what your neighbors are, in terms of their architecture and their scale, but also if there is a public potential vista or view, you should be at least sensitive to that.”

He points to a small streetside flower garden with a view of the harbor that serves as a backdrop for everything from tourist selfies to formal wedding photographs.

He notes an open porch on the side of a home he designed.

“That satisfied his goal of having a porch, but also you look through it and you see the harbor,” he says.

At the next home on the street he points out a new garage. The neighbors across the street were concerned about losing their water view.

“There’s no legal right that they have to that,” Mr. Ahearn notes. “But I said to my client, look, if we’re going to do this one-story garage addition, let’s make sure that we do it of a certain height so that they can see across to the harbor. It’s not going to hurt you, and why not be accommodating.”

It’s not much of a stretch for this architect to write a book. He uses writing techniques to create a back story for his projects, which then inform the design features he draws.

He started his Island career by placing a series of ads in the Vineyard Gazette, pen and ink sketches of homes to gauge interest. — Mark Alan Lovewell

“When I do my work, I call it writing the narrative like a novel, or a script like a movie,” he says. “I go back in the wayback machine, and I kind of make my own history if there isn’t a history to make. When I did my house on Davis Lane, I said, okay, my house is a midshipman’s house from 1790, and in the early 1800s, they grew the house with a barn at the back. In the late 1800s that family moved into the barn and then they built a livery stable at the back of the property. That’s the story of my house.”

It happens to be entirely fictitious, but the story fits the kind of home he wanted to live in, smaller, not so ornate, and a building that blends in perfectly with the 200-year-old houses that surround it.

“I tell people to walk down Davis Lane and find the two new houses, he says. “They can’t find them. I call it non ego-driven architecture. At the end of the day, you never knew I was even here.”

Mr. Ahearn’s new book Timeless (subtitled Classic American Architecture for Contemporary Living), is a lush tome with hundreds of pictures of Edgartown homes. He says his intention was to pass along some of the lessons learned.

“I’m 67 years old, I’ve been doing this for 44 years,” he says. “I really felt that my message about how I practice is important, not just for my clients, but even for other architects and other architects to be. I wanted to create a kind of primary about how you work in scale, and how the spaces between the buildings become important, and still be able to accommodate a client’s program, but also teach them about the public good theory, teach them about the context in which you work.”

If success is any measure, there is little doubt Mr. Ahearn is qualified to write about architecture.

“I’ve done 172 houses within 12 blocks in the last 25 years,” he says. “I think I’m doing the right thing.”

Patrick Ahearn’s book Timeless, published by ORO Editions, will be on sale in bookstores beginning Dec. 15. Preorders can be made at