most cases, the new materials are simply creating new problems in pollution-control, occupational health, and recycling (Geiser, 2001, p. 237-258) Engineered wood products are one of the most important recent expressions of technology in building materials, and they have had a major impact on residential construction over the past twenty years. As cellulosic products, they constitute an important part of the Carbohydrate Economy. But while they are comprised of largely renewable materials, they are man-made, and so embody some of the most positive and negative aspects of industrial production. Although they do not really rate as advanced materials, they are quite different than traditional materials and they also environmentally outperform most of the so-called advanced materials. Engineered wood products have tremendous potential to become ecological materials by making the most of wood waste and wood by-products. Some of these engineered materials can dispense with wood altogether by replacing virgin wood fibre with agricultural residues. But this category of materials has some issues to resolveparticularly around wood certification and toxic bindersbefore these products can be unambiguously embraced as green materials. The most significant use for engineered materials thus far has been for structural components like beams, joists, studs, and window and door frames; but there is growing use of engineered sheet goods for wallboard, subflooring and sheathing, as well as production of engineered products for siding, flooring and trim. Engineered materials and engineered systems for floors and wallshave had a major impact on the way housing has been built over the past two decades (Gonzalez, 1999), and engineered wood is used in around 40 percent of homes built today in North America (Heavens, 2002).