When most people think of locations for a holiday home, they have visions of beaches, golf courses, spas, and chalets. But few have the mettle to choose the sort of place that architects André Lessard and Barbara Dewhirst deemed perfect. “We first saw the site on a rainy fall morning,” Dewhirst says of their Otter Lake, Ontario, weekend spot. “The place was overrun with hemlock trees, and it was dark and gloomy. We immediately decided to buy it.”

The price might have been right, but, like so many eager home builders, the couple found that buying the land was the easiest part of the ordeal. Construction was delayed for years, and the whole process took nearly a decade due to factors like stringent local environmental building codes and cash-flow concerns.

On most weekends the architects would make the six-hour round-trip drive from their Toronto home to camp on the 32-acre plot with their three boys, who were three, five, and nine years old when they bought the property. At first, the children were urbanites, more accustomed to taxis and lattés than tree frogs and lichen, but the new spot proved better than the Boy Scouts when it came to teaching them about nature. “The kids didn’t expect to be living on such a rugged, swampy property,” Lessard says, slightly embarrassed at the recollection. “The first time they saw a beaver swimming through the water, they thought it was a crocodile.”

The boys quickly adapted, chasing wildlife around the lake in a canoe and helping their parents landscape—an arduous task that involved clearing logs from the water, trimming the hemlocks, and building a fire pit. The time spent roughing it also enabled the family to envision a structure perfectly suited for the site. There were some environmental constraints—local codes required a 100-foot setback from the lakeshore—but nothing limited their aesthetic choices; to further the rustic feel they opted to place the house 300 feet from their shared driveway. Ardent modernists as well as proponents of green design, Lessard and Dewhirst chose to build a tall house on higher ground further from the water in lieu of clearing trees. The three-story triangular tower both maximized their views of the water and minimized their footprint on the land.

Mindful of the road’s inaccessibility, yet understanding the need for a sturdy structure, the architects chose to construct the frame out of ten-guage steel beams—each ten-foot piece weighting no more than 25 pounds. To ensure that the house wouldn’t blow over in a stiff wind, Lessard and Dewhirst enlisted the expertise of a friend, structural engineer Eric Jokinen. Jokinen’s initial surprise at the choice of building material gave way to admiration, leading him to dub the house, La Tour des Bébelles, in reference to snap-together metal toy sets.

Two workmen helped carry in the beams, then assembled them on-site with nuts and bolts over the course of a month. Wood stud walls and a cladding of stained tongue-and-groove pine helped create the shell of the building. The result, Dewhirst observes, is that the house doesn’t disrupt its surroundings; it “looks like it was plucked from outer space and plunked directly into the forest.”

The interior of the house is as unconventional as the exterior. La Tour de Bébelles has no divisions within: It’s essentially two large, open rooms, each measuring 450 square feet, stacked one on top of the other. A deck was built underneath so that rainy days don’t deter lounging outside on the Adirondack chairs. The only private area in the whole place is the space that contains the shower, sink, and composting toilet, which has been afforded four walls. “As a reaction to Victorian homes, where the bedrooms are light and the lower rooms dark, the bedrooms here are placed below the living area,” explains Lessard, letting people slumber in dim peace, then eat and play upstairs, and outdoors, in the light.

Although the house is rigged up to the electrical grid, everything else about it is resolutely green. All drinking water comes from a well beside the house, and the family collects graywater for use in the kitchen. To protect the lake, they use only biodegradable soaps and truck their laundry to nearby Laundromats or—before their recent move to Vancouver—back home to Toronto. There’s no lawn as such; instead, Dewhirst speaks fondly of some saplings she’s tending. Lessard dragged granite chunks from other parts of the land to create steps up to the house from the lake, cutting a path between the few small areas of grass and wildflowers.

Over the years, the boys have become accustomed to the deer, beavers, loons, porcupines, and other animals that traipse across their land, and, as Lessard boasts, “You can catch fish in the lake with a pail.” It’s an idyllic existence for any earth-friendly folk, although one that the family can’t claim as frequently since they headed west to British Columbia last spring. “We don’t miss Toronto at all,” says Dewhirst. “Our only regret is leaving Otter Lake.”