That this year's Custom Builders of the Year are Andrew Goldstein and Charles Barry will come as no surprise to those involved in high-end custom building in the Boston area. In fact, some might ask why it took so long. For more than a decade—and the Roaring '90s at that—their West Acton, Mass., company, Thoughtforms, has been the team to beat in its top-of-the-market niche. High-profile architects have chosen the company for their most demanding residential projects, and even for their own homes. Would-be competitors have considered it a career milestone to be interviewed for a project along with Thoughtforms.

Preeminence in any field is remarkable, but custom building in particular resists it. Competition is fierce; the playing field is always changing; skilled workers can skip to another company and be productive immediately; a key employee can become a competitor literally overnight. How Thoughtforms has achieved and maintained its standing is a story with many parts. But the best place to start is out in the field, and approaching a wooded, pond-view construction site not far from the company's offices, Goldstein sets the scene for the project we are about to tour. “It's probably the most difficult house we've ever built,” he says.

Coming from Goldstein, that is not an idle statement. Thoughtforms lives and breathes difficult projects. The company's offices are lined with photographs of houses, any one of which most builders would be proud to call the achievement of their career: palatial homes of limestone and marble, restorations of grand historical structures, contemporary buildings that explore the limits of construction technology. Goldstein is mum on square footages and project costs—the company zealously protects its clients' privacy—but the pictures say it all. Somewhere there may be a builder with a more impressive portfolio. If so, we would like to meet him. In this market, a Thoughtforms sign says a lot more about a house than simply who is building it.

And this one, even in the framing stage, is unmistakably a Thoughtforms house. Designed by Schwartz/Silver, the architects responsible for Boston's New England Aquarium, the building's concrete-and-steel form owes as much to physiology as to architecture. The plan curves like an undulating school of fish. Roof planes describe the gentle sweep of a bird's wing. There may be a right-angle corner around here somewhere, but it's going to take a while to find it.

Project supervisor Bob Gustin begins the walk-through at a subgrade garage opening. From here, an interior drive will lead, Bat Cave fashion, to a parking area at the opposite end of the building. “There are seven different levels of concrete down here,” Gustin says. An elaborate web of steel beams supports the thin concrete slab above. “I think there are over 400 beams in the house,” he says, noting the biggest: a 33-inch-deep behemoth that weighs 221 pounds per lineal foot. “That's the biggest beam I've ever put in; that's bridge material.” The structure of the three levels above is a steel moment frame that allows for the glass curtain wall that will wrap most of the building. “There are 60 columns on the first floor,” Gustin says. “With this house, there's not really room for error.”

“It's more complex than most skyscrapers in many ways,” says project architect Michael Price, “because of the geometry of it.” To help nail down the more than 60 radiuses in the foundation and wall framing, the architects provided a separate “geometry plan,” covered with circles. To describe the compound curves of the roof surfaces, the roof plan includes contour lines (the steel I-beams that support the roof follow the same compound curves). To build this house, Price says, “only a handful of builders were even potential candidates,” and among those, “Thoughtforms was more experienced at this level.”