Making houses out of trash.

• Author: Douglis, Carole
• Position: Construction materials out of recycled material

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...