The exterior is almost ready in 12 hours; move-in is only eight weeks away – modular housing is attracting lots of middle-class attention. By Ross Atkin | Staff writer of The Christian Science Monitor

It's "set day" on Paris Way, a suburban cul-de-sac in Woburn, Mass., and you can feel the excitement in the air. Nicholas Zervoglos and a clutch of family members have gathered to watch the assembly of Mr. Zervoglos's house.

That's right, it will be assembled, not built. This two-story colonial was built to the owner's specifications at a factory in southern New Hampshire, then transported to the site near Boston on trailer trucks. Set day is when the boxes, or modules, that make up the house are secured to the foundation and to each other. Bolts, spaced about every two or three feet, are tightened along the center beams and the perimeter beams attached to the sill plate.

It is an event that attracts the attention of neighbors and passersby and is considered maybe the most effective sales tool in the modular-house business.

A crane hoists modules that measure as much as 14 feet wideby 60 feetlongand weigh 20,000 to 25,000 pounds.

This day, they are lowered with the help of a small crew from the manufacturer, Epoch Homes, and positioned with great precision. The "boxes," or modules, come with windows, doors, light fixtures, cabinets, preprimed interior walls, and siding on the front and back (the rest is put on after the modules are joined). In most cases, hardwood or carpeted floors are also already installed. (Tile and other finishing touches come later.)

Mr. Zervoglos and his sisters, who also are having houses built on the cul-de-sac, have their cameras out to chronicle this important chapter in family history, as his parents, who provided the land, and two preschool-age nieces look on.

While modular homebuilding is not exactly new – it got its start in the late 1940s, according to Building Systems Magazine – this form of prefab construction appears to be gradually catching on as buyers realize that modern modular doesn't mean second-rate or boring, and that factory construction has its efficiencies and advantages.

Zervoglos's older sister, Daphne Barbas, learned about it from extensive research on the Internet. Her findings, supported by visits to three factories, convinced her siblings to opt for modular homes.

"It makes sense," says Scott Jones of James V. Caggiano & Son Inc., a general contractor in Saugus, Mass. "After all, they don't build cars out in the field; they build them in a factory."

Some observers think it's only a matter of time before many American homes are built in factories, as most are in Scandinavia, rather than on-site.

As the on-location builder for the Zervoglos home, Mr. Jones's company is responsible for site preparation and for the finishing work, which may take six to eight weeks to complete after the house is set.

The company does both traditional "stick-built" and modular construction, and has built about 300 or 400 modular homes since the early 1980s. Jones remembers the time when modulars were viewed negatively, and some subdivisions had covenants banning them.

"When we first started," he says, "modular was somewhat of an inferior product, and priced accordingly. Today, it's not that way – and in some ways, they build modular better."

Building in a controlled environment means that workstations and the labor force can be tailored to the task at hand, with sophisticated machines used to guarantee level and square construction.

An additional advantage is that because the modules are trucked to the site, the construction must be solid enough to withstand road vibration.

Modular homes should not be confused with mobile homes (which the industry now calls "manufactured homes"): There are definite differences. Yet the public's tendency to lump them together accounts for some of the marketing difficulties that modular homes have faced.

Both are factory-built, but mobile or manufactured homes must conform to a different – and, generally, lower – federal building standard than modulars, which must be built to local – often more exacting – codes. Also, manufactured homes are built on a chassis, so they can be moved; modulars are as permanent as any site-built house.

Neither housing type is as predictable-looking as it once was, thanks to building advances and computer technology, which allow for more options and flexibility in the design process. Roofs can be made more steeply pitched, for example, and rooms made more spacious with higher ceilings. Better finishing, from floors to moldings to cabinets and doors, is also often part of the package.

But for some buyers, cost matters more than customization. In Iowa, moderate-income families can buy simple modular ranches from the nonprofit Rural Housing Institute for as little as $47,000.

And in Needham, Mass., Harvard University's Graduate School of Design has submitted a plan to build a flat-roofed, two-story modular home to help address the Boston suburb's need for more affordable housing.

In contrast, one mansion in Connecticut consists of 22 modules.

But modulars don't have to be fancy to be stylish, a fact that John and Lennie Martin learned while living in Maryland, not far from a modular factory.

"A lot of people in the area buy modular homes, and often, when we told people we liked their home, they'd say, 'Believe or not, it's modular,' " she says. "That's how we learned."

After they fell in love with quiet Pungoteague, Va., near Chesapeake Bay, as a permanent retirement residence, they concluded that a modular home would be right for them, too.

The waterfront cottages they looked at needed substantial fixing up. And a conventionally built new home, they were told, might entail a wait of of two or more years in order to schedule busy local contractors.

Dwindling numbers of skilled craftsmen and subcontractors are a concern in the building trades, a fact encouraging a generally slow-to-change industry to adopt a more assembly-line approach. This keeps tradespeople employed year-round, protects materials from job-site damage and theft, and lessens the complexities and aggravation associated with scheduling contractors.

In fact, Mr. Martin once had such a nightmarish experience arranging for subcontractors to finish a conventional house that he didn't want to go that route again.

This time the Martins had to wait only two months from the day they ordered their house to the time they moved in.

While a compressed time frame is generally viewed as a plus, they point out that the faster pace might not suit everyone.

Lenders, for instance, become accustomed to conventional construction taking three or four months and may be surprised at how quickly the paperwork needs to be ready for a modular home.

When going modular, it's important to look beyond the base price, the Martins say. In their case, the base price was $109,000, but they ended up spending about $142,000. Part of that was due to certain extras they wanted – more insulation, an additional sliding glass door, and a two-car garage. But the additional amount also included surveys, septic system, land, and closing costs.

The couple is especially pleased that they were able to flip-flop the house's orientation so that the best views are out back onto a Chesapeake Bay tributary.

Finding a good local builder, in the opinion of Scott Jones, the Massachusetts contractor, is every bit as important as the selection of the modular company. When the modules show up, there's still plenty of work to do, including making sewer, water, and electrical connections. If a builder states otherwise, he says, a customer should be cautious.