Eight years ago, West Mount Airy architect Reinhart Struzyna found himself with some extra land and a good idea that could go very badly: Design and build a house that would sit barely 100 feet from his own, for clients who would become his neighbors.

Considering that he's seen couples divorce over mere renovations, he didn't take the prospect lightly.

But it was during the recession, and business was slow for his firm, Dovetail Design-Build. His own house sat on 21/4 acres, so he had land to spare. And it was a once-in-a-lifetime chance - to design the view over the fence.

"I wanted the opportunity to build a house in a style that pleased me," he said. "Most of the work I do as an architect, you're working to meet your clients' needs."

The style that pleased Struzyna was exemplified by Shofuso, the improbable Japanese house that sits in Fairmount Park, designed by midcentury modernist architect Junzo Yoshimura and relocated there in the 1950s by way of the Museum of Modern Art in New York.

"To me, it's one of the most beautiful places in Philadelphia," said Struzyna, who stumbled upon Shofuso on a bike ride years ago and returned often to study its simple contours. "I think of it as a muse."

So, he crafted an homage to Shofuso that would get along amiably with its neighbors, including Struzyna's own house, a stately stone structure dating to 1910. It would echo the Japanese house's low-slung profile and curving roofline. Yet it would incorporate current technology and materials that acknowledge the site: a stone base supporting a stucco exterior that gives way to wood tones above.

He posted a rendering of what he called "the Evergreen House" on his website, planted a sign on the lawn, and waited.

For months, he fielded inquiries that led nowhere. Most people, he said, were unaware of the cost of building a custom house. Then in 2012, Carla Walters and Tony Cooper spotted his sign. They had been looking for a residence in the area that would have a first-floor bedroom for their retirement years. So they called, motivated by curiosity and by frustration over their long search.

"When we walked out of the meeting, we pretty much decided we had to have the place," Cooper said.

Struzyna said it was a meeting of minds.

"They wanted something that had a degree of quality, but that wasn't large or ostentatious," he said. "I wanted the house to be really energy-efficient, and to be only as big as it needed to be."

The resulting structure is 3,000 square feet, with geothermal heating and cooling and a whole-house ventilation system - a request of the couple, who at one point had six cats.

They broke ground in fall 2012. Struzyna, a woodworker by hobby and a perfectionist by nature, watched from next door and often assisted as Paoli builder NL Drass Construction erected the frame and grappled with the roofline - which was both the greatest engineering challenge and the most crucial factor in evoking Shofuso's quiet elegance.

In 2010, Struzyna had spent hours at Shofuso, watching as craftsmen brought over from Japan restored the traditional hinoki cypress roof. But replicating that curved silhouette using modern construction methods wasn't simple.

They figured it out, piecing plywood planks together to create the concave eaves, and trimming the A-frame with sapele, a renewable African mahogany with a warm red tone.

Those overhangs also serve a green design function, Struzyna noted: "It shades the windows in summer, when the sun angle is high, and lets light in in the winter, when the sun angle is lower."

As a result, even in wintertime, it's warm inside the Evergreen House.

Within, it's a panorama of exposed wood, including the walls and a wooden ceiling, made of a single layer of Douglas fir planks that double as the floor above.

The staircase is also a sculpture in wood: interlocking cherry poles and maple treads, handmade by Old Road Furniture Co. in Intercourse, Pa., and assembled on site.

In keeping with Shofuso's dimensions, the rooms are modestly proportioned. (Walters and Cooper gave up on trying to buy new furniture and had their old sofa and chairs from the 1960s and '70s reupholstered.) In the living room, a row of sliding glass doors suggests Japanese screens.

But this is America, after all. So Struzyna made space for a large, eat-in kitchen with slate floors, granite counters, and a tall arched window.

Above, a second-floor sitting room looks out onto the kitchen and through that window to the view beyond. Initially, the plan had called for closing off that space to create a bedroom.

"But," Cooper recalled, "Reinhart called me one night at 9 p.m. and said, 'I'm standing on the second floor looking out at this view. Why are we closing this in?' "

So they adjusted, one of many modifications to Struzyna's original design along the way. Walters and Cooper also asked for their own tweaks, including a room for a small indoor pool.

Not long ago, the couple visited Shofuso and were struck by how much it felt like home.

"We didn't realize how much of an influence it was until we visited there ourselves," Cooper said.

Struzyna likes to say building a house together is the test of a relationship. Cooper and Walters figure they passed. They moved into the house in October 2013 - and, a year later, got married.

As for the relationship with their former architect, now neighbor, they are coexisting in a Zen fashion.