If the term “prefabricated house” conjures visions of double-wide trailer homes, think again.
Today’s factory-built houses run the gamut from log chalets as massive as their boulder fireplaces to rambling, farmhouse-style residences that look like they’ve been in the family for generations.
Although houses built “on site” (also called “stick-built”) still comprise the majority of today’s new houses, prefabs are gaining ground. About 30 percent of today’s new houses are at least partially built off-site, according to Building Systems magazine. This is up from 10 percent a decade ago.
The prefab house isn’t a new idea. Catalogs, including those of Sears Roebuck and Co., sold thousands of them prior to World War II.
Lustron Corp. made steel houses in the 1940s that are architectural collector’s items today. And renowned architect Frank Lloyd Wright dabbled in the prefab concept in the 1950s.
But “prefab” and “high-style” didn’t find themselves in the same sentence until recently.
Now manufacturers offer factory-built homes and components in a wide range of price points and architectural styles, plus customization.
“Prefab” is an inclusive industry term that refers to houses made completely or partially in factories.
“Modular” houses are comprised of box-like sections that are trucked to the job site, then hoisted into place by cranes.
“Kit” houses are the modern-day versions of the Sears houses; they arrive unassembled with instruction books.
Prefab, modular and kit houses are built according to local building codes that are enforced where they will be erected. So in some cities, that may mean they are a no-no.
Mobile homes, on the other hand, have been called “manufactured houses” since 1976, when the Department of Housing and Urban Development building code that regulates them went into effect. They are built entirely in a factory and hauled to the site.
“I call mine a ‘poor man’s Mies van der Rohe,’
” says artist Marian Anderson, describing her 1,400-square-foot kit building that serves as her studio in South Haven, Mich.
Built in 2005 near her lakeside house, she uses the kit house as a place to make sculptures. Clad in glass, it echoes van der Rohe’s revered minimalist houses.
Purchased from Perryville, Mo.-based Rocio Romero LLC, Anderson’s studio has a steel-post-and-beam frame.
Inside, she ditched bedroom walls in favor of a large, sunlit space. She figures she spent about $120,000 on the project, including labor to construct it and to dig the crawl space under it.
Rocio Romero, the company’s principal, says she’s seeing prefab houses appear across the U.S., after they were embraced in California years ago.
“When I first started in 2003, there was a huge learning curve,” says Romero. “Now buyers get it.”
“The industry has matured,” reports Tom Beers, vice president of the National Modular Housing Council in Arlington, Va. “It’s been growing every year except in ’07, when new housing has been down overall.”
Prefab manufacturers don’t compete with traditional builders, Beers said. Rather, they supplement their businesses because most prefab home buyers hire contractors to erect their houses.
“The builders tend to be small builders who build on scattered sites, as opposed to large ones that build big developments,” added Beers.
The advantages of building prefab benefit both the builder and the homeowner, says Beers.
“Material cost is lower because the manufacturer can buy in bulk and labor cost is lower because it takes less time to erect the structure,” he says.
Because the prefab house is built in less time than its stick-built counterpart, the homeowner can avoid additional costs such as carrying two mortgages or renting while waiting for the new house to be completed.
“The whole assembly took two weeks,” says Julian Guerrero of the prefab house he and his wife Nancy had built in north suburban Park City in 2003. “We sat in lawn chairs and watched.”
The Guerreros’ 2,100-square-foot ranch arrived via truck in three modules from Hi-Tech Housing in Bristol, Ind., then was assembled by R.J. Construction from Twin Lakes, Wis. Counting their full basement and labor, they estimate they spent $200,000. That includes extras such as a skylight and whirlpool tub.
“The craftsmanship is awesome,” says Guerrero. “It has 2-by-6 insulated exterior walls, so our gas bills are lower than those of neighbors with stick-built houses.”
Indeed, many prefab home manufacturers tout the “green,” or Earth-saving, aspects of their products.
Mifflinburg, Pa.-based Ritz-Craft Corp., for example, makes all its homes Energy Star-compliant. Modular manufacturers say their methods produce less waste for landfills. And, it is in their best interests to minimize transportation costs, which translates into less use of fossil fuels.
Kit houses made by Enertia Building Systems in Raleigh, N.C., employ envelopes of air between their all-wood exterior and interior walls. The houses become their own heat pumps, extracting warm air from underground.
Buyers of prefab log structures have long recognized the green aspect of their homes.
“The logs soak up the heat in the summer, so we rarely use air conditioning. In the winter, the logs hold the heat in and we use the furnace less,” says Conrad Golonka of the kit log house he bought from Expedition Log Homes in Oostburg, Wis., in 2001.
“This house is bigger than our old house but our utility bills are lower,” he said.
Built in St. John, Ind., the Golonka house has 3,000 square feet.
Meanwhile, back at Chicago-area cornfield subdivisions, many builders of stick-built houses are using more factory-built components.
These include SIP (structural insulated panels) walls, roofs and floors. SIPs are sandwiches of OSB (oriented strand board) or plywood on the outside and foam on the inside. They arrive with window and door openings already cut out. They can hold in more heat or cooling than traditionally insulated walls.
Other builders use walls, floors and ceilings that are pre-cast of concrete. These are especially popular in hurricane-prone areas. Like SIPs, they are joined together on the job site.
“Panelized” houses are made of factory-built walls, floors and roofs that are fastened at the job site. The term “panelized” typically means the sections are made of wooden studs. But steel frames also are made in factories and shipped to job sites. The latter can span wider lengths because of its greater strength. .
Thanks to computer-aided design, prefab houses now can be tailored to fit rugged terrain, too, thereby junking the notion that they are all flat boxes plunked down on empty lots.
Mark and Peter Anderson’s book, “Prefab Prototypes: Site-Specific Design for Offsite Construction,” shows prefabs that dangle from cliffs, hug hills and hide among treetops.
“You can’t tell a prefab from a stick-built one,” says Guerrero. “But I think you get a better-built house for less money. I encourage other people to consider it.”
