Alternative Building Materials
From high-tech to timber frame, today's houses are being built with more than wood and brick. Come see your choices.
Structural Insulated Panels (SIPs)
What They Are: Fiberglass panels are made from insulating foam sandwiched between two layers of structural material.
Advantages: Walls can be erected quickly, usually within hours, compared with about two weeks for traditional stick (lumber) framing. The panels are lightweight and are already filled with insulation when they arrive on the site. Since the insulation is installed in a controlled environment and is measured to fit precisely, the house is likely to be more airtight than a conventionally built home -- an energy-efficiency plus.
Disadvantages: This method is about 10 percent more expensive than stick building. And a builder needs to be well versed in the process to make sure the panels fit together precisely.
What It Is: Homes are built in-factory, then collapsed and taken to the home site and erected with cranes. Though mobile homes are most often associated with this type of construction, the market has grown to include homes that very closely resemble conventionally built structures.
Advantages: Once the homes are transported to the site, cranes can erect the walls within hours. Today's modular homes can also be custom-designed to include such features as tray ceilings, coffered beams, and spiral staircases. Like SIPs, modular homes are built to precise specifications in a controlled environment so they are more likely to be airtight than a stick-built house.
Advantages: The method supports heavier loads and provides longer-lasting frame construction. Steel framing is dimensionally stable and eliminates most drywall cracking. As is the case with other nontraditional exterior materials, houses framed with steel can be finished with any exterior material.
Disadvantages: Although steel framing is similar to traditional or stick framing in the construction process, the construction materials are vastly different, and builders need to be trained to use them correctly. Some builders mistakenly assume that if they're able to build stick houses, they build with steel equally well.
Polyvinyl Chloride (PVC)
What It Is: PVC is a hard, durable, synthetic material that is becoming a choice in new construction and remodeling. Though the plastic is rarely used for whole-house building, its popularity is escalating for gutters, window frames, shutters, and siding.
Advantages: Proponents say PVC materials last an average of 20 years with little or no maintenance. PVC pipes for water distribution, chemicals, and sewage have been used for up to 50 years and are still in service. The material also boasts excellent fire-retardant properties.
Disadvantages: PVC is essentially plastic, and it looks like plastic. Though it's widely used for garden and landscaping structures, its popularity as a whole-house construction material may be a long time coming.
What It Is: Timber framing combines handcrafted timbers with time-honored building techniques. The timbers are cut, shaped, and finished, then sent to the building site, where specially trained crews erect the house frame.
Advantages: Timber framing is time-tested; it has been used for more than 600 years and was widely used in Northern Europe before being brought to America. The oldest timber-frame structure in the United States was built in 1637 and remains in use. Timber-frame homes are usually sheathed with stress skin panels, insulated exterior sheathing that carries exceptional insulation value as well as the benefit of quickly enclosing a timber frame from the elements.
Disadvantages: Since few people build with this method, it could be difficult to find someone who's suited to tackle your project.
Autoclaved Aerated Concrete Blocks (AAC)Lightweight concrete blocks have been used in Europe for decades.
What They Are: These insulating and lightweight blocks are made from concrete mixed with chemicals that cause it to rise like dough in an oven. The mixture is pressure-cooked until its mass is about 80 percent air.
Advantages: It's virtually as strong as concrete, but lightweight and easy to handle during building. It's time-tested in Europe, where it's been a popular construction method for decades.
Disadvantages: It's expensive -- about 20 percent more than traditional building methods.
Advantages: The method builds durable houses, and the forms are easier to handle than concrete blocks. The rebar offers extra stability.
Disadvantages: Again, it's more expensive than traditional stick building -- about 15 percent more, and many builders are unfamiliar with it.
What It Is: Thin layers of wood are glued together, then microcured to form large, solid planks and beams.
Advantages: The method offers more dimensional stability than conventional lumber.
Disadvantages: It costs 5 -- 10 percent more than stick building, and early engineered-wood products raised concerns because of out gassing problems. However, the microwave curing has essentially eliminated those.
Special Note: Today's housing market includes an array of alternative building materials and methods. To find out more about each, search the Internet or contact the National Association of Homebuilders (NAHB) at 800/368-5242 or visit www.nahb.com.