Another advantage of modular houses is less construction waste. Construction of an average 2,000-square-foot (186-square-meter) house produces 8,000 pounds (3,600 kilograms) and 20 cubic yards (15 cubic meters) of waste. In a factory, wood building materials are recycled, either by using them on other houses or for burning to heat the factory.
Modular construction also has advantages in remote locations, where it may be difficult to find builders. Suitable materials may also be inaccessible or expensive because of transportation costs, making it often easier to transport modules than to build from scratch. When building a second home, the homeowner may not be available at the construction site to make daily design decisions. With a modular house, those decisions are made before the start of construction.
Factories can use the most up-to-date equipment to cut and assemble wall, floor, and roof sections, which are assembled on large horizontal frames to ensure flat and level surfaces.
For standard houses, most homeowners get a one- or two-year warranty. Many modular houses come with a 10-year warranty. Modular houses are built to comply with national building codes. Inspectors visit the factory and perform code-compliance checks. Some modular houses are built to exceed local structural requirements.
Michelle Kaufmann began designing modular houses when she and her husband, Kevin Cullen, were considering building their own house. Kaufmann wanted an economical house that could be built quickly, while Cullen wanted the house to be eco-friendly.
Her first modular design, the Glidehouse, met these requirements. The Glidehouse was such an enormous success that Sunset magazine asked Kaufmann to join them in designing a second modular house. The result of that partnership is the Sunset Breezehouse.
Like her previous design, Kaufmann chose to "create a home design that embraced the environment and was an alternative to the inwardly focused McMansions." Kaufmann's designs are influenced by her upbringing in Iowa, where she observed the way farm buildings incorporate many sustainable elements. They use durable, low-maintenance materials, and their layout and window placement take advantage of breezes that can cool on hot days.
Kaufmann designed the Breezehouse for casual indoor-outdoor living in which garden areas would be connected to the bedrooms, master bath, entryway, and kitchen. One of the most innovative features of the house is the "breezespace," which is a glass-enclosed breezeway in the center of the house covered by a butterfly-shaped roof.
Walls of glass fold like accordions to open up the breezeway to the house. The space functions as the main living and dining area. It is flanked by the kitchen and second bedroom in one wing and the flexible library/ guest room/ office and master bedroom on the other side.
Custom Choices and Finishes
Most modular designs can be customized to a degree, which Kaufmann had been doing to Glidehouse designs. But she soon discovered that to take full advantage of factory production, she would have to limit customization and offer a selection of configurations and materials.
Although options are limited, a homeowner can still get an individualized Breezehouse design. They can choose from one of several different roof configurations, from a variety of positions for the side modules (which can be parallel, perpendicular, or slanted), and from several types of exterior siding, including wood, cement board, and steel.
They also can pick whether they want a two-, three-, or four-bedroom house. Kaufmann also offers a complete package of interior options in her modular houses, including paint, flooring, faucets, and other finishes.
Once a buyer selects the design and layout and orders the house, they simply wait for it to be delivered. Site-built houses require much more time and frequently include a number of change orders and progress meetings.
The Breezehouse can be delivered about six months after the order is placed. It arrives 90 percent complete, with walls painted, floors and cabinets installed, and wiring, plumbing, and heating coils built in. The house can be set in two days. Once utility lines are hooked up and glass walls installed, it takes just four to six more weeks until the homeowners can move in.
Kaufmann has always been concerned about sustainable design and incorporates it into her plans. In the Breezehouse, she uses cross-ventilation for cooling and stone tiles that act as a thermal mass to absorb heat during the day and radiate it back at night. Windows, clerestories, and skylights maximize natural light and ventilation and minimize the need for artificial lighting.
The breezespace roof unobtrusively supports optional solar panels and screens glare. Ecofriendly options available are no-VOC (volatile organic compound) paints, bamboo flooring, and kitchen and bathroom countertops made of Richlite — a recycled paper product.
Although the prototype Sunset Breezehouse is built to suit a moderate climate, Kaufmann can alter the design for colder climates by reducing the amount of glass in the breezespace or adding insulated panels that slide to cover the glass walls. If built in a heavy snow area, she says, "we would increase the structural sizing and spacing to handle larger snow loads, and slope the side module roofs to allow the snow to slide off."
Poised to Grow
Modular construction is growing rapidly. Although in its infancy, the industry will spawn new factories to serve new locations. Designers and builders are now using timber-frame and log construction in their modular houses to add to the design options.
Good sources of information are the Modular Building Systems Association and the National Association of Home Builder's Building System Council.
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Sheri Koones is a member of the National Association of Real Estate Editors, the Sustainable Building Industry Council, and the American Society of Journalists and Authors. Previous books include From Sand Castles to Dream Houses and Mainstreet Modular.
This article is excerpted from Prefabulous: The House of Your Dreams Delivered Fresh from the Factory, copyright © 2007, available from Taunton Press and at Amazon.com.