Making houses out of trash.

As forests around the world are torched or cut, environmentalists track the numbers of hectares deforested and of species lost. But there's another, less commonly known indicator of forest decline: the shrinking size of the trees that remain. The average diameter of timber felled in the Pacific Northwest of the United States, for instance, declined from 14 inches in the mid-1970s to 7 inches a decade later--and is continuing to fall, says Steve Loken of the Center for Resourceful Building Technology in Missoula, Montana.

One consequence: Solid wood buildings once considered cheap--such as the log cabins, barns, or rough-sawn frame houses erected by earlier generations of Americans--have lately become luxuries. Where large, fresh-cut logs were once abundant, lumber mills and their customers are now learning to make do with other materials. "The largest old-growth trees are gone," says Loken, "so now we're trying to find ways of taking smaller pieces of wood, and engineering systems to extend the resource base--kind of like using 'Hamburger Helper'."

Ways to "stretch" wood include using thin wood veneers on visible surfaces, reusing lumber from dismantled buildings, and replacing the solid wood beams normally hidden in walls and ceilings with laminates made from thin strips of scrap wood glued together. Sometimes builders replace wood with plastic, fiberglass, aluminum, or more low-tech materials such as adobe. In a modern update of an old prairie building technology, a Tucson, Arizona builder, Matts Myhrman, makes highly insulated outer walls by covering straw bales with stucco. Construction and design entrepreneurs also use trash as a resource, turning newspaper into attic insulation, windshields into iridescent floor tiles, plastic bottles into shingles and carpets, and aluminum soft-drink cans into roofing. Fly-ash, a by-product of coal combustion, can substitute for cement (which has a high energy cost to manufacture) in concrete foundations. And a New York company, Ring Industries, is experimenting with making construction blocks out of paper sludge--the gunky residue (inks, varnishes, and excessively short wood fibers) that remains when used paper is recycled.

From the scores of "resource efficient" construction methods being tried, a few may eventually make their way into the industrial mainstream. Among the most promising candidates is a form of modern-day alchemy that turns used paper, cardboard, and other fibers into virtual lumber. Researchers at the Forest Products Laboratory (FPL) of the U.S. Forest Service in Madison, Wisconsin, pioneered this technology in the early 1980s.

The technique involves pouring a slurry of fibers from waste paper into a rubber mold that looks like a waffle iron, vacuuming most of the water out through tiny holes in the mold, then heating and press-drying the fiber mat. The result is a tough, lightweight fibrous panel with a honeycomb on one side and a flat surface, or "skin" on the other. Gluing two of these panels together creates a structural panel of waffle sandwiched between two smooth faces. The material--named "spaceboard" by the FPL because of the spaces in the honeycomb--can be made paper-thin for packaging, and as thick as 75 mm (3 inches) for walls, roofing and floors. The panels can be flat or curved. The lattice can be left empty or filled with insulation, or even concrete, for foundations. Spaceboard can be sawed, nailed, sealed, painted, laminated, coated with fire-retardant, and covered with cloth or wood veneer. It's non-toxic as long as non-toxic adhesives are used to apply the covering. Most important, in some uses it can be stronger, pound for pound, than lumber, plywood, particle board, and other common construction materials.

The FPL patented spaceboard in 1987, then recruited private partners to help develop the product commercially. The venture furthest along is that of the Carlsbad, California-based Gridcore Systems International, which markets spaceboard under the trade name "Gridcore." The company has begun by developing lightweight panels for the trade show display and film-making industries. The spaceboard made by Gridcore is less fussy than recycled paper about its raw materials, so it can make use of a far wider array of trash--40 to 70 percent of what fills landfills now, according to some estimates. Gridcore can be made from newspapers, glossy magazines, mixed waste paper (without de-inking), lumberyard and backyard waste, old phone books, textiles, sawdust, fiberglass, crop residue, and even plastics.

In his latest show for Home Box Office television, film director David Lynch used Gridcore for the set, and the Alliance of Motion Picture and TV Producers is testing it. The chief reason: Gridcore substitutes competitively for luan plywood, the traditional set-building material. Luan--light, strong, flexible, and consumed by Hollywood by the thousands of tons annually--comes from rain forests under pressure in Indonesia, Malaysia, and Southeast Asia. Environmentalists have pushed to halt its use for the screen.

The Franklin Noble Corporation, which is affiliated with Gridcore Inc. and is also based in Carlsbad, has won the right to market Gridcore for transport vehicles--planes, cars, trucks, and boats. According to the FPL's supervisor of research engineering, Theodore Laufenberg, possible uses range from airplane tray tables to wings--in which Gridcore would substitute for aluminum. Perhaps the most important long-term use for spaceboard, however, may be in the manufacture of low-cost housing. California officials have asked Gridcore Industries to build a working prototype of farm-worker housing--for which technical standards are currently less exacting than those for commercial housing--while the company continues work toward getting Gridcore code-certified for regular construction.

From a structural standpoint, says Noble, the advantage of this method of making houses out of trash instead of trees is that "the engineered honeycomb is so strong that Gridcore alone becomes a whole wall assembly." A panel of Gridcore provides the combined services of interior particle board or sheet rock, structural studs, and exterior sheathing all in one, making on-site construction faster and cheaper than is possible with conventional "stick"-building methods. Noble aims to make inexpensive Gridcore houses strong enough to have withstood Hurricane Andrew, the megastorm that demolished 47,000 houses in southern Florida in 1992.

Gridcore Systems International is scheduled to launch its new factory in Long Beach, California, in December. The company plans a basic product line of four-by-ten-foot panels. A three-quarter-inch-thick panel cut to four by eight feet (a standard U.S. size) will weigh about 20 pounds--about half the weight of a comparable sheet of plywood. Within a year, Noble expects to be churning out panels at the rate of about 250,000 annually. That rate would save about 5,000 tons of virgin lumber a year--or some 95,000 trees of six-inch diameter. Initial prices will be competitive with the current materials of the trade show and stage set industries, says Noble.

Gridcore is designing a closed loop system for the factory: water will be cycled through the plant, to avoid discharging fibers and heat into the environment. And the company plans to buy back as much Gridcore as possible--particularly panels used in Hollywood sets--for reuse in furniture, signs, props, and art supplies.

Though its debut is literally taking place on the glitzy stage of Hollywood, spaceboard may ultimately prove to be of greatest value in poor countries--especially those where forest resources have been badly depleted. "Making this stuff can be as low-tech as you need," says Noble. "It's as easy as can be to operate the equipment, and raw materials are available everywhere." A prospective producer who doesn't have access to much paper or cardboard can use rice straw, wheat chaff, sugarcane waste, sawdust, bamboo, jute, kenaf, or just about any crop residue. In fact, nearly anything with cellulose fiber will do. Moreover, high-quality panels can be made without energy inputs other than muscle: People in an unelectrified village could mechanically press the wet fibers, and dry the product on a rack.

Spaceboard and other resource efficient materials open up a new way of looking at construction. "We're still overusing lumber--whittled trees--and underusing other fiber resources," says Noble. But he expects that "Within a decade our whole method of utilizing fiber will be turned completely upside down. We'll have highly efficient, economical manufacturing methods for using other sources of cellulose fiber."