It takes 20 minutes to drive from central Stockholm to Vendelsö, one of many villages that define a wet and woodsy urban fabric. Two million people inhabit this convoluted archipelago; the bright city center, big-box stores, and cookie-cutter housing clusters are interspersed with plenty of seawater, lakes, granite, and conifers. Mårten Claesson is behind the wheel, and we are en route from his office to his architecture firm’s first completed prefabricated house.

The Plus House—named for the perpendicular trajectories of light and air that pass through on the top and bottom floors—is one in a series of architect-designed homes commissioned by Arkitekthus, a development company founded five years ago with a pledge to improve the quality of prefab architecture. The company offers 12 models from four acclaimed Swedish architects: Thomas Sandell, Tham & Videgard Hansson, Gert Wingårdh, and Claesson Koivisto Rune (CKR). Almost all of the models are now in production, and Arkitekthus has sold more than 60 units.

“You could argue that it’s not true architecture,” says Claesson of the Plus House, “because true architecture has to be specific to a site. But prefab houses are so ubiquitous in Sweden, and most of them are crappy. When we found out there was a market for improving the aesthetic, we were happy to contribute.”

Whereas in the United States prefab can sound rather exotic (with the important exception of trailers and tract houses), in Sweden it’s a way of life, comprising 70 percent of the single-family housing market. And it isn’t some high-tech method where rooms descend onto steel frames like pods—it’s just a way of building that has developed since the postwar years because finishing components in the factory saves resources and time. “Kit” or “catalog” are more oft-used adjectives for these houses than prefab. Companies tend to offer several models with various sizes, floor plans, and details.

Claesson’s critiques refer to Sweden’s most popular sort of single-family catalog house, with a pitched roof, lots of small windows, and clapboard cladding, often painted red—an archetype Americans might associate with New England. Their look is willfully old-fashioned, like a PT Cruiser. “I’m provoked by that,” Claesson says of consumers’ tendency to choose such houses. “Would those people want to drive a Model T? No! But they want their house to look that old.”

Nonetheless, rolling up the driveway to the Plus House’s hilltop lot, the first thing one notices is a pitched roof atop classic old-fashioned proportions. “Normally we do everything we can to avoid a pitched roof,” says Claesson, “but this time we decided to try for a new interpretation of the typical old form.”

Mikael Bossel, who owns the house with his wife, Suzana, switches off his lawn mower to greet us. Looking across the lawn, you can see through the house: The long walls of the ground floor are completely glazed. Suzana is inside with their children, Molly and Jake, aged four and six.

Moments later we are all standing on the spruce deck, gazing up and down the facade. Claesson explains how the spruce panels that coat the second-floor exterior will fade in tandem with the gradual dulling of the zinc-coated steel that rims the glazed doors and windows, eventually winding up the same color. “They will go gray like we do,” he says with a hint of jubilance. The natural finishes are a striking departure from the typical kit house.

The Bossel family moved into their home a year ago from an apartment in central Stockholm that was half the size. “We needed more space for the kids,” Suzana says. “The tricky part was finding a plot that we liked and could afford. When we saw this place we fell in love at once.”

Molly and Jake love it too, especially the ground-floor layout, with its central box-shaped wall around the stairwell—perfect for running around in a perpetual game of tag. The family has begun to add touches to make the Plus House their own: an Oriental rug and giant poufs in the TV room, mini Panton chairs for the kids’ playroom, and a vintage dining table by the kitchen. Claesson’s vision for furnishings might have been more austere, but he isn’t bothered. “I don’t want to be like Frank Lloyd Wright,” he says. “I don’t need that amount of control.”

Mikael has embraced the freedom to add characterizing details to the house. In front, he’s been working on a Japanese-style garden. “Before we moved in the plan was to have sand or gravel, maybe raked in nice patterns. But with two kids in the house, grass is better to play on, and I don’t have to freak out every time my Zen pattern is destroyed,” he says in jest, as he watches a portly construction worker approach from a neighboring lot that’s being excavated, hauling several big, lichen-covered rocks on a forklift. After placing the decorative rocks on the lawn, he leaves, carrying a bottle of Glenfiddich given to him by Mikael.

The addition of the Bossels’ personalities and the lived-in quality brought about by two young children is welcome seasoning for a house that was designed on spec. When developing the Plus House, CKR had no site—nor did they have a client, per se. They were creating the house for Arkitekthus, but the developers did not plan to live there, and they gave such an open brief that the architects took several months to find a workable approach to the design. “Creativity needs boundaries,” says Claesson. “Often our clients give us too much freedom because they think making requests will inhibit our creativity. But for us it’s quite the opposite.”

So CKR made their own constraints: They decided to embrace zoning regulations and market demands by building a pitch-roofed, two-story, typically proportioned house that still looked modern. Rather than site-specific, their approach was more site-generic, emulating a form descended from barn houses and ubiquitous to the Swedish landscape.

The Plus House nevertheless takes on a radical appearance, because on each story two whole walls are glass—the long sides of the ground floor and, on the second floor, the triangular walls beneath the roof.

The orientation of the house, which is symmetrical in plan, exemplifies the non-site-specific design, as no single wall is intended for sun or shade. On all sides, the architects drew the windows in from the facade, so however the house is sited, a three-foot overhang adds some shade when summer sun streams in.

Buyers of Arkitekthus houses pay a premium for architecture, which might equal the royalty fee that CKR receives for each one—though the company did not divulge all the details of its business strategy. Nonetheless, the premium isn’t huge: Sköna Hus, the manufacturer for Arkitekthus, usually charges 3 million Swedish Krona, about $475,000, for a 2,150-square-foot house for one of the other development companies for whom it manufactures homes.

At 1,750 square feet, the Plus House costs nearly the same, relative to size. Despite actually comprising 400 feet fewer, the Plus House appears larger to most people who visit, because its open glass walls create a sense of expansiveness. Sight lines throughout the house lead straight into the woods or across the nearby estuary, and the architects added details to maximize this effect. On the second floor the doors slide, rather than swing, which means that they can remain open without taking up space, and the gaps between each step in the stairwell provide a view to the outdoors on the way upstairs.

“The first time it snowed,” Suzana remembers, “with all the whiteness, you just felt the floor extending.” Claesson puts it a little differently: “Normal houses are just smaller, even if they’re not.”