Approaching downtown Wellington, New Zealand, from the airport, you curve around the city’s glittering bay and land in Courtenay Precinct, a stylish neighborhood chockablock with boutiques, bars, and sidewalk cafés. It’s hard to believe that just a decade ago this was one of the city’s least appealing areas, its prime landmarks a sketchy bus depot, a belching incinerator where the city burned its trash, and a commercial port where cargo ships docked to unload their wares. Warehouse-lined streets erupted at daybreak as produce markets took over the neighborhood, leaving squashed tomatoes and cabbage leaves in their wake. “It was really quite scungy,” reflects Jan Bieringa, who with her husband, Luit, bought one of the area’s rundown mercantile buildings in 1996. The Edwardian warehouse on the corner of Blair and Wakefield streets is a few blocks from the water. “At the time, this was a very neglected part of Wellington. Not many people were moving into the inner city. But we thought it was fantastic.”

Dedicating themselves to their new neighborhood and determined to take an active role in its transformation, Jan and Luit sold their suburban house and took over the building’s raw, 3,000-square-foot third-floor space (“Hard to heat, but great for playing soccer with the dog,” Luit says). They lived and worked in this open-plan space for four years as they gradually strengthened and renovated the building, renting out the other floors to creative, like-minded professionals and shop owners. (Luit is a freelance curator and the former director of the National Art Gallery of New Zealand; Jan works in film and new media.) “The idea was to develop a creative community within the building, and to avoid transient tenants like nightclub or restaurant owners,” explains Luit. “We wanted to get people on the streets during the day, to help make it a vibrant neighborhood.”

After four years, Luit began itching for a new project, not to mention a more permanent-feeling residence. He hired his architect friend James Fenton, director of the local firm Architecture Workshop, to design a rooftop home. It took just a glance around the neighborhood, where neighbors had begun expanding their own buildings skyward, for the pair to come up with some definite conclusions about what they didn’t want. “People around us were generally just extruding what was below, creating a fourth floor by repeating the base,” says Fenton. “But that destroys a building’s proportions, turning it into something stretched out and unfortunate-looking.” The better approach, Fenton believed, was to juxtapose what was already there with something entirely new, yet respectful of the original structure. So after a few napkin-sketch starts, the pair came up with a design that contrasts the muscular bulk of the existing building while at the same time echoing its structural lines: a trio of glass-walled, three-story apartments. As Fenton explains, “We decided to play with mass—to crown the heavyweight base with a lightweight top. The building was a strong frame with unusually large windows. So we took the size of the windows to an extreme, and made the apartments almost all glass.” Taking a minimalist approach suited Luit just fine: “Jan and I are dreadful gatherers of art and books—the last thing we needed was a space cluttered with details and materials.”

In order to secure a construction loan from their bank, the Bieringas had to pre-sell one of the apartments off the plans. They approached their longtime friends Tony Hiles and Judith Fyfe and found willing and eager partners—on the condition of a few design tweaks: namely, the nixing of a Jean Nouvel–inspired barrel vault that was to arch over the three units (“It would have blocked the view,” Hiles explains. “I live visually—I didn’t want a wooden hairnet in my way”) and the ability to design their own kitchen. Both parties anticipated the risk inherent in working so closely with good friends. Hiles confesses: “Right away, our concern was: We love them now, but how will we feel about them every bloody day—how will that work?” But to their delight, they’ve found themselves very compatible neighbors. It helps that they’re all self-employed and independent people, Hiles explains. “We respect each others’ need for time and space. We get together for dinner once a week, but we don’t live in each others’ pockets. I thoroughly enjoy living next to someone I can bump into, and then the very next minute we’re having tea.”

The design of the apartments inherently promotes this sense of community (ditto the fact that both the Bieringas work one flight down, in open-plan offices carved out of their former loft apartment and shared, as envisioned, with other creative industries). The three apartments’ sunflower-yellow front doors open onto an outdoor corridor that parallels the sidewalk 40 feet below, encouraging casual encounters between the residents (the third apartment was purchased, postconstruction, by Catherine and Murray Heyrick). One of Hiles and Fyfe’s three decks hangs over this entranceway, allowing them to pop their heads over the railing to say hello if they’re feeling social, or to duck away if they’re seeking solitude.

Inside the individual apartments, this public-private interface continues, with privacy decreasing up a vertical gradient. The top floors are the most transparent, reading as a series of intercutting glass boxes that overlay and lock into each other, offering eye-popping views of the surrounding hills and cityscape as well as unexpected glimpses back into the apartments. Tying it all together is an open central stair, which allows sounds and light to travel throughout the three floors.

Yet even the most compatible partners and neighbors need some alone time—a challenge in a space with so few walls and so many windows. “Glass is a material you have to be careful using,” Fenton says, acknowledging that a sense of comfort is just as important as architectural gestures when it comes to designing people’s houses. “You can’t mess with people’s comfort zones too much when you’re dealing with the place where they spend all their time, because the last thing you want them to feel is on edge. You have to stimulate without wearing them out.” To that end, he devoted the more cellular lower level to the three small bedrooms, tucking them behind the original building’s parapets to give the residents a feeling of security. On the top floor of each apartment is a lofted, nestlike room that Hiles calls the “blob-out room,” which he says his grandkids love for the same reasons adults do: “You can hide out up there, but you’re not totally separate from what’s going on in the rest of the apartment.”

Still, there’s not much hiding to be done in an apartment their neighbors refer to as “the fishbowl.” When they’re asked the inevitable question—how do they feel about being on display to whoever passes on the street below—all six residents declare themselves unfazed. “All they get if they look up—and they rarely ever think to—is one goldfish, maybe two,” says Luit. “But when we look down, we see hundreds—the whole of humanity in all its grotesqueness and delightfulness.”

In fact, these days when they look down, there’s a lot more to see than passersby. The burgeoning neighborhood is rife with new investment and promise. Teenagers swarm a skateboard park on the revitalized waterfront, and cranes hover over a luxury high-rise under construction on an adjacent lot. Locals stroll down a harborfront boardwalk, past a grassy lawn speckled with picnickers. It’s a thrilling bird’s-eye view—and even more so for those tenacious residents who have witnessed its evolution.