Nancy Hanover and Gerardo Reyes had already obtained permits to add a conventional bedroom/retreat to their 1923 bungalow when they happened to read a newspaper article last spring about a cutting-edge prefab called Glidehouse.

Taking its name from its gliding glass wall, the eco-friendly house, designed by San Francisco architect Michelle Kaufmann, is made of 14-foot-wide factory-built modules that come with plumbing, wiring, storage and shoji-like wooden screens already in place.

Hanover and Reyes, both elementary schoolteachers who say they are Modernists at heart, loved the "economical beauty" of its design, at a price -- about $200 a square foot -- they could afford. "We're very interested in spaces, but we are also working people," Hanover said. So they opted to do something unorthodox: Build a 573-square-foot modern prefab add-on to their classic Craftsman-style house.

Today, dozens of architects and designers are experimenting with prefab, putting a decidedly hip new spin on manufactured housing.

When did prefab get cool, losing its nasty associations with double-wides and the look-alike boxes of Levittown? Modern prefab housing has been popular in Europe for decades (increasingly so, thanks to Ikea and other sponsors), but the new surge in interest in the United States can be traced to January 2003. That's when San Francisco's Dwell magazine announced a competition, inviting 16 architects and designers to design a forward-looking prefab house with a budget of no more than $200,000. This summer, the prototype of the winning Dwell Home, designed by Joseph Tanney and Robert Lutz of the New York firm Resolution: 4 Architecture, was unveiled in Pittsboro, N.C.

"We ended up buying every bottle of water in the county," said Dwell Editor in Chief Allison Arieff, who expected 500 visitors at the sweltering site and got 2,500.

Michael Sylvester, an architect and business consultant who created a Web site, www.fabprefab.com, sees prefab frenzy as a function of growing visual literacy in the United States. Trained by exposure to beautiful modern objects, from the iPod to the reborn Volkswagen Beetle, people want reasonably priced houses that reflect their taste and reflect well on them.

"There are a lot of people out there who are wide-eyed and excited about this idea," Sylvester said. "They feel like they're design savvy and design aware" but see little, if anything, they want and can afford in the conventional real estate market. Popular culture reinforces their craving for products that reflect midcentury Modernism, then and now: "Look at commercials and films today -- you see the visual language of success at the moment is Modernism," he said. In a world where Brad Pitt hangs out with Rem Koolhaas, Sylvester has a point.

Prefab housing in America is "not a new idea," said Jennifer Siegal, an architect at the Office of Mobile Design in Venice, Calif., and creator of the two-story Swellhouse, fashioned from prefab steel modules. "It's an idea that's been out there, but it's being reinvented."

In fact, prefab predates the Declaration of Independence. Seventeenth century religious dissenters sailed from England with Bibles, black clothing and houses that had been taken apart to be reassembled in the New World. House kits were shipped to prospectors in California during the 1849 Gold Rush. Thousands of people ordered kit homes, even apartment buildings, from the Sears catalogue and other sources during the first few decades of the 20th century. The mail-order house was delivered to the closest railroad station in thousands of pieces, and owners could put it together themselves, piece by numbered piece.

Today's modern prefab has its roots in the Airstream trailer, World War II Quonset huts, the Case Study houses and such quirky attempts to streamline construction and shelter the masses as the metal-clad postwar Lustron homes. "It's very in keeping with the [Machine Age] ideal of Modernism," said Virginia Postrel, author of "The Substance of Style" (HarperCollins, 2003), "using technology and manufacturing innovation to produce good design that is available to a mass market."

Now Target, that unlikely purveyor of affordable objects of desire, has entered the fray. Ubiquitous designer Michael Graves is offering three prefab "pavilions" of varying degrees of modernity through Target. Costing $10,000 to $26,000, the customizable kits are produced by Lindal Cedar Homes and can be used as offices, guest rooms or what have you.

On a smaller scale, dozens of youngish architects are beginning to market prefab dwellings to a consumer audience starved for good, affordable, environmentally sensitive design -- one that can be characterized as people who tend to have more taste than money.

Kaufmann's prefab has such amenities as concrete counters, bamboo floors, low-VOC (volatile organic compound) paint and an on-demand tankless water heater.

Artist-designer Michael Jantzen creates what he calls M-vironments. He is finishing a steel-and-concrete house near Gorman, Calif. Its frame consists of seven eight-foot interlocking steel cubes, on which he has hung rectangular panels of different sizes, some containing insulation. Jantzen's M-house looks like a gigantic futuristic toy. He sees it as a playful, habitable sculpture that is more "puzzle" than traditional residence. The structure, which can be reconfigured, is a possible prototype for a kit of recyclable parts that "could be put together a thousand different ways," Jantzen said. "As I change, I may want my space to change as well -- that traditionally has been very hard to do."

Even the high-end architecture firm of Marmol Radziner and Associates is experimenting with prefab. Leo Marmol is building a vacation house for himself out of prefab steel modules on a five-acre site in Desert Hot Springs, Calif. It could be the prototype for a prefab house that the Los Angeles firm might be able to offer for less than $200 a square foot. "There's no question that there's huge local interest," said Marmol, who has received many phone calls from eager potential clients.

The media tend to gush about modern prefab, but Sylvester's Web site gives a more nuanced view. In the chat rooms, griping is rampant. "I don't get it," one visitor groused recently. "Why is it so hard to get these prefab companies off the ground? My wife and I want one, half of our friends want one, yet the majority of the companies listed on this site have not produced more than a prototype."

Because, Sylvester responded, modern prefab is dominated not by mass marketers but by small architectural firms and because prefab is as much about "process innovation" as about design. "Architects wanting to crack the prefab puzzle need to spend as much time examining and designing processes as they currently spend thinking about objects," Sylvester said. "This may not be their forte."'

At this stage, Sylvester says on his home page, "modernist prefab is still more of a meme [a contagious idea] than a marketplace."

In a very real sense, Modernist prefab dwellings are products, and their success will depend on their designers' ability to maintain quality and coordinate manufacture and delivery. Sylvester predicts a market of prefab houses at many different price points.

Hanover and Reyes expect their addition to cost $117,000, not including work at the site. Shipping will add $20,000 more. The couple like the fact that prefab is less wasteful of materials, and they're thrilled they won't have to be home to supervise weeks, or months, of relationship-testing on-site construction.

For them, prefab is simply a way to get more space with less hassle, while honoring their appreciation for modern design. Says Hanover: "It'll be an addition that has an architect behind it, and it solves our problems."

Designer Michael Jantzen turned eight-foot interlocking steel cubes into a playful, habitable sculpture that is more "puzzle" than traditional residence.Michael and Ellen Jantzen relax in a downstairs bedroom at their "M-home" near Gorman, Calif.