Ben Wright’s home addition arrived last week on the bed of a flatbed truck wrapped in sheets of plastic. One by one, the pieces of the new second floor were lifted off the waiting trucks and rearranged like a puzzle on top of his brick Bethesda rambler. The new roof was in place by the end of the week — just in time for Hurricane Isabel.
“They just lifted it into place with a crane, then bolted it in place,” Mr. Wright says. “We put up the roof right before the hurricane.”
The 1,600-square-foot addition, including four bedrooms and two bathrooms, was built by a Pennsylvania company and shipped directly to Mr. Wright’s front door. The technique, known as modular construction, offers homeowners a new way to add on to their existing homes faster than with traditional, or stick-built, construction.
Second stories such as Mr. Wright’s can be in place in as little as 14 weeks, compared with the six to nine months to construct a conventional second-story addition.
The building method is not new. It was first touted by such companies as Sears, which offered the mail-order industrialized homes popular in the 1940s. Today, modules are built assembly line style in warehouses. Additions are completed in sections, then shipped directly to customers for installation.
The industry has grown dramatically, increasing 27 percent in the past decade. Last year, 36,000 single-family homes and town houses were built using the modular construction method, an 11 percent increase nationwide, says Eric Fulton, communications manager for the Building Systems Councils of the National Association of Home Builders (NAHB).
“People think ‘manufactured,’ and they automatically think ‘mobile homes,’ and that’s blatantly untrue,” says Mr. Fulton. “Modular is just a style of construction; it’s not a mobile home.”
There are currently 65 modular manufacturers nationwide registered with the NAHB. They offer homeowners design choices ranging from master suites and master bathrooms complete with whirlpools to floor plans for studies, dens, offices and family rooms. Mr. Wright’s home includes fixed stairs to the attic. There is enough headroom to allow him to finish off another level up there.
Modules are made indoors at the manufacturing plant and assembled based on detailed computer designs completed by structural engineers. Each module comes complete with interior doors, fresh paint, light switches, plugs and lights. The roof, complete with shingles, is set on top, then unhinged on-site and folded open into place.
The additions can be completed by the manufacturers in as little as 10 days. Installation takes longer, though, because of the extensive finishing work. The additions include air-conditioning and heating systems. Plumbing and electrical work are linked to the existing house.
“It’s a fairly completed unit,” says Pat Fricchione, president of Simplex Industries, a modular-construction company. “It’s three-dimensional. The drywall is fully insulated and completed, the rough plumbing is in, and the bath fixtures will be set before it is shipped out.”
The process saves time and cuts costs, providing homeowners with a completed addition in 90 to 120 days. Mr. Fricchione says.
Modules save 5 percent to 15 percent of the cost of traditional construction techniques, Mr. Fricchione says. Mr. Wright’s renovation will cost about $150,000 because he is completing much of the finishing work himself. A typical custom addition for his home would cost $300,000 to $400,000.
“I just couldn’t afford a custom-made addition,” Mr. Wright says. “I’d been thinking about it for a while, and when rates hit rock bottom, I said, ‘That’s it.’”
Modular-construction companies work the same way as conventional builders. Projects start with an on-site visit by structural engineers to determine whether a house can accommodate a second-floor addition. Because modules must be transported via highways, they can’t be wider than 15 feet 9 inches across, so the projects have to be completed in pieces and might not work in with larger homes or rooms.
Before signing up with a contractor, homeowners should be careful to research local zoning ordinances and requirements. Many communities have height requirements that might not allow for a modern second-floor addition.
For many of the rambler homes built in the 1940s and 1950s in the area, the modules offer an alternative way to add on. The homes are preferable because they meet design requirements capable of carrying the load of a second floor, but they might not be an appropriate choice if the first floor also has to be transformed once the second floor is completed, builders warn.
“The foundation walls are strong enough, but these houses don’t have a modern floor plan,” says Steve Perlik, owner of SEI Design/Build in Vienna. “It doesn’t correct the deficiencies of the first floor.”
Homeowners should consider expanding outward before deciding whether to add a second floor. However, on tight lots with strict zoning requirements, many have no choice but to build up, he says.
If you choose to add a second story, make sure builders incorporate architectural details and design plans to make the house fit together. A completed plan should include such details as matching siding, paint, shutters and windows.
“Typically, we would design front porches with this type of project so the first and second floor are linked,” says Thomas Hemphill, owner of Hemphill and Associates of Falls Church.
Design plans also should try to match the house’s existing plumbing structure to further cut costs. Designing projects around existing plumbing helps to avoid the cost of ripping up too much of the infrastructure. Mr. Wright’s second story was designed around the available plumbing lines. The modules also have to have a load-bearing wall in the center of the home capable of supporting the new second story.
“You have to look at a house and see what you’re talking about,” Mr. Wright says. “You can’t violate the load-bearing wall, and you shouldn’t violate where the waste pipes are located to save money.”
The result was a second story with rooms located on both sides of a hall centered along the load-bearing portion of the project. A section also has been reserved for the new heating and air-conditioning system to be installed in the attic, he says.
Mr. Wright’s addition has stirred neighbors’ curiosity. Several people have stopped by to ask questions and take a tour.
“At least 10 people have knocked on my door since this whole thing started,” Mr. Wright says.