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The Foam Home
Imagine a house built almost entirely of foam a material similar to that used in a coffee to-go cup you get from your nearby fast-food restaurant. Now imagine that the same house was built without wood framing, drywall, nails, bolts or screws; that it consumes up to 80 percent less energy than a typical home; that it conserves natural resources; and that it is resistant to fires, earthquakes, mold and termites, and can withstand winds of up to 150 miles per hour.
That is precisely the house Mike and Cari Schofield bought in the Hidden Hills Community in Scottsdale, Ariz. In fact, it took the couple only 10 minutes to decide that this was the house they wanted for themselves and their three boys Blake, 11, Spencer, 7, and Evan, 5, who is allergic to dust and a slew of other allergens.
Although this was a major purchase, when the builder's representatives told us how environment-friendly and energy-efficient the house is, it took us less time than buying a car to make up our minds, says Mike Schofield.
Not for a minute were the Schofields afraid of the risks involved in being the first homeowners to invest in a brand-new method of construction, nor are they afraid of not being able to resell the home when the time comes to move on. I think the benefits far outweigh the risks, and I really don't see any downside to this house, Schofield says. But I do think that as an individual who cares about the future of his children, you have to take a stand in the world and do something for the environment.
The Miracle of Composites
The Schofields house, a 3,300-square-foot, flat-roofed pueblo/Santa Fe-style structure, was built by Three Rivers EcoBuilders of Phoenix, Ariz., in cooperation with Strata International Group, Inc. of Glendale, Ariz. To construct the home, the builders used panels of expanded polystyrene, which were coated on either side after assembly with a concrete composite containing fiberglass and polymer fibers.
The fusion of the concrete composite and polystyrene provides so much structural strength that the entire house, including the walls, floors, ceilings and roof, could be built without standard wood framing, nails, screws and bolts.
That is the miracle of composites. When two materials the polystyrene and the concrete composite are bonded together, they become extremely strong, says Nasser Saebi of Strata International Group. The polystyrene and concrete coating by themselves are not strong; it is the fusion of the two materials that makes them strong.
Composites of one kind or another have been around for years, says Saebi, a structural engineer who spent 11 years developing the patented technique that makes this type of construction possible. However, he notes, the use of these materials in the building industry was limited because architects didn't have a practical solution for analyzing the performance of the structural members of a composite building.
So Saebi developed his own system a computer-aided design (CAD) and manufacturing (CAM) system. He uses it to calculate how each structural member of a building will react to a given load and to determine how strong the concrete composite coating needs to be to fit the design and conditions to which the building will be exposed, including wind, seismic and snow-load stresses.
Combining elements of drafting, design and manufacturing, the CAD-CAM system guides a computerized robot in cutting 8-by-4-foot polystyrene panels to precise shapes, which are then delivered to the site and assembled. Typically 8 inches thick for the outer walls and 6 inches thick for the inner walls, the panels are grooved so they fit together easily. Seams are reinforced with low-emission glue.
After the box is assembled, it is sprayed with the fiberglass-reinforced concrete mix to a thickness of one-quarter to one-half an inch, depending on the building's design, says Carl Tichenor, Strata's communications liaison. The coating aids in sealing the joints and works with the foam to form the structural composite. In the Schofield house, stucco was applied directly to the coating on the exterior walls and plaster to the interior walls.
Foam Has Its Benefits
Building with foam provides a number of benefits not present in conventional building. From a design perspective, there is no other building system that has the flexibility of this system, says Thomas Hahn, principal architect and founder of The Sol Source, based in Phoenix, and vice president of construction for Three Rivers. We can build anything that can be drawn into the computer, whether it's circular, arched, angular or curved. While out-of-the-ordinary elements like arches and curves are expensive to build with conventional or alternative-building methods, this system makes it possible to do them with little extra cost.
Although the $850,000 cost of the Schofield home is similar to that of conventional houses of the same size in the neighborhood, both Hahn and Saebi are convinced that when foam homes are built in large volume, costs can be reduced to make them more affordable, since savings can be realized in a number of ways.
Basically, there are only two materials involved -- the polystyrene, which is 98.5 percent air, and the concrete coating, which consists of a relatively thin layer, says Saebi. There are no outlays for wood framing, steel reinforcements, insulation, nails and screws. As a result, there are savings on both labor and materials, he says, adding, More savings can be realized by taking a variety of measures, such as painting or staining the concrete composite floor instead of adding other floor coverings.
There are savings after construction as well, thanks to the energy efficiency of the polystyrene. With 8-inch-thick walls (R-40) and a well-insulated roof, the home's energy consumption is reduced by up to 80 percent, compared to conventional buildings. Installing only one five-ton AC unit instead of the usual two in a conventional house the same size resulted in immediate up-front savings. A heat pump and a Trane AC/heating system, which allows for zone heating and cooling, will add additional energy savings over the years.
Another benefit of the foam building system is the ease of repair and remodeling. When, during construction, a heavy truck rammed into a wall of the house, it took virtually no time or money to repair the damage, says project manager Greg Martin. Had it been a conventional house, it would have damaged the home's structural integrity and taken four different crews to replace that section of the wall, at a cost of $1,000 - $2,000. In this house, the structural damage was zero and the repair cost was only $20.
In addition, Martin says, Moving a window or door from one location to another is as simple as cutting out a piece of the panel and adding another panel in the cavity you want to convert into wall space.
For environmentally conscientious homeowners like the Schofields, conserving lumber and other natural resources addresses their concern for the future of the planet, as well as for their family's health.
Another bonus is that the insulated concrete floor and tight building envelope prevent radon gas, a health hazard present in Arizona's soil, from leaking into the home. The downside is that the tight building envelope also keeps out fresh air. This problem was solved by installing an air-to-air heat exchanger, which conserves energy by passing heat between incoming and outgoing ventilating air streams, says Hahn.
Since polystyrene is resistant to water, there is no need to worry about moisture condensation, mold and mildew, or the destructive effects of floodwater. In addition, the absence of wood keeps termites and other pests away.
For those concerned about out-gassing of the polystyrene, Hahn notes that much of the pentane (an odorless gas) that is used in the production of polystyrene is squeezed out of the foam before it leaves the plant. The result is a product that meets food-grade standards. In addition, says Hahn, during construction, the building is exposed to sun and wind, so any traces of gases have a chance to escape.
The Future of Foam
Currently, Strata is working on a number of projects in Utah, Florida and Arizona, says Tichenor. One potential project is to provide housing for Mississippi workers engaged in the Gulf Coast recovery.
In addition, we have been asked to bring our technology to Dubai (in the United Arab Emirates), he says. Their primary interest is what we can do with this architecturally, without being limited with a framing concept that results in a modern box.
The company has also been approached by Turkish officials, who are interested in building sturdier homes in an effort to prevent more mass fatalities like those Turkey has experienced due to frequent earthquakes.
Tests have proven that our building system would be good in all areas of the world, including in areas near the ocean, as well as areas that experience hurricanes, earthquakes and wildfires, says Saebi. My goal and aspiration is to produce affordable, functional and good-quality housing with an acceptable appearance for people around the world, housing that can withstand the forces of nature and will conserve the resources of our planet, which are increasingly stressed by the demands of an expanding population.
Lydia Enderle Bell wrote about the Hydrogen House in the Sept./Oct. 2005 issue. She is based in Scottsdale, Ariz.