On a cold day in January, homeowners Nick and Catherine Swezey stood in their kitchen looking up at the sky. The roof of their 1923 bungalow in Washington, D.C.'s Kent neighborhood had been torn off to make way for a prefabricated addition on top of the house.
"That was one of the most dramatic moments presented by this project," said Nick Swezey, advertising director for the Weekly Standard magazine. "We crossed our fingers it wouldn't rain that day."
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Fortunately, the weather cooperated and three prebuilt structures were hoisted by crane the next morning and assembled into their home's second story within the day. The new 900-square-foot level adds a bedroom, a bathroom and a walk-in closet for the homeowners, and a pair of bedrooms and a bathroom for their daughter Charlotte and son William.
"Our kids were thrilled when they could look into their rooms on the ground before they were lifted into place," Swezey said.
This type of construction, made off-site and transported to a property, is still a rare sight in most neighborhoods. Called modular, manufactured or systems-built, it accounts for only about 1 or 2 percent of the national residential and commercial construction markets, said Tom Hardiman, executive director of the Modular Building Institute, a trade association based in Charlottesville, Va.
But pre-made modules, once considered formulaic and flimsy, are becoming more common as a faster, cheaper and less wasteful alternative to conventional stick-built construction, experts say.
"Perhaps because of the recession and certainly as a result of heightened awareness of sustainability, many owners, developers and architects are demanding more efficiency from their contractors," said Hardiman. "This, in turn, is forcing contractors to re-examine previously ignored methods such as modular."
Proving his point is Case Design/Remodeling Inc., the Bethesda, Md.-based company responsible for designing the Swezeys' addition. "This was our first modular project," said Bill Millholland, a Case executive vice president. "We got into this type of remodeling to do it in a less expensive and faster way."
Once the addition was designed, Case tapped Icon Legacy Custom Modular Homes LLC of Selinsgrove, Pa., to fabricate the structures. Windows, wallboard, crown and base moldings, bedroom carpeting, bathroom vanities, mirrors, toilets and tub were already set into place when the structures arrived on a flatbed truck. Roof rafters and sheathing were prebuilt and hoisted into place, and roof shingles were installed by the end of the day.
The control over construction quality in the factory and accelerated construction schedule convinced the homeowners to try the modular method. "It's a very efficient process. We were able to get the square footage we were looking for in a shorter period of time -- six months of design and construction versus the nine to 12 months it would have taken to stick-build the second floor," said Catherine Swezey, who works for HotelMe.com, a hotel review website.
Advocates of modular building assert that prefabricated construction is more cost-effective than conventional, on-site methods.
Project designer Matt Dirksen of Case Design/Remodeling said that the cost of the Swezeys' modular addition was about $14,000 less than a stick-built addition of comparable size. "The savings allowed us to customize parts of the second floor and open up the first floor for more family living space," said Catherine Swezey.
The prefabricated sections of the second level cost about $325,000, she said, but additional funds were needed for exterior upgrades, including Hardiplank siding on the upper and lower stories, and a new front porch. The couple also spent more on interior renovations and refinishing the wooden floors on the main level.
Looking at the home, with its continuous siding rising to gabled roofs, it's hard to tell the difference between the prefabricated upper story and the original house. The seam between the two is covered with a band of trim.
For the prefab construction to be cost-effective, Dirksen said, the site has to be clear of obstructing trees and power lines, and the house must have a simple building profile. He said challenges such as crane access and complicated assembly of modules contribute to higher expenses.
"Modular can save you money, primarily in labor costs, but we learned it depends on existing conditions," said the designer. "It helps if the existing house is well built and square, and the modular design is simple and put together in a logical way."
Installing a prefabricated addition isn't a matter of plopping down a box, Dirksen said. It requires working within the idiosyncrasies of an older home, making sure the new addition aligns with existing stair openings, plumbing pipes and structural framing, which may be uneven after years of settlement.
"We learned there is a lot of extra work we had to do to make the connections between the original home and the new structures," said the designer.
The Swezeys' 1923 home had to be strengthened to support the upper-level addition, so new posts were added inside the existing walls. The old chimney flue was sealed to make way for the second floor, and the wood-burning fireplace in the living room was converted to gas and vented through a side wall.
After the prefab addition was set in place, plumbing lines, ductwork and electrical wiring were installed and connected to existing systems. Drywall in the new rooms was then finished and painted, lighting was installed and marble and tile floors were added to the bathrooms.
"Without thoughtful planning, a modular project can have a cookie-cutter result," said Catherine Swezey. "We saw the opportunity to plan for lighting, finishes and flooring as an overall benefit. It allowed the whole project to run smoothly and we avoided having to make last-minute, emotional decisions."
In adding the second story, the homeowners lost one of their favorite features of the home, a soaring cathedral ceiling in the living room. But Case was able to provide almost 9-foot ceilings throughout the main level and open up a former master bedroom at the side of the house to supply daylight to the adjacent living area.
That first-floor bedroom, added to the side of the house in the 1970s, was turned into a family room. Zebra-patterned armchairs and an ottoman made of woven banana leaves, purchased by Catherine Swezey on a trip to Bali, add exotic touches to the otherwise traditional decor of the space.
The family room provides access to the new staircase connecting the first level to the added second floor. Built by Crown Stairs & Rails in Gaithersburg, Md., the staircase extends above the hall stairs leading to the basement to save space.
Four years before the modular addition was completed, the couple remodeled their kitchen with new cabinets, marble countertops and appliances, and added built-in bookshelves to an adjacent office at the front of the house.
Those improvements appeared slowly compared to the single day it took to install the new second story. "The change happened so fast," recalls Nick Swezey. "To have a house you know, to become completely different the next morning is remarkable."