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SUSTAINABLE MATERIALS

Environmental impact was a key consideration in the selection of materials to be used in the construction of the house. For each building component, the resource efficiency of the various options available was assessed, and efforts were made to select materials having one or more "green" characteristics.

Although ecological concerns have heightened awareness of the need to protect the world's forests from overconsumption, wood continues to be a desirable building material. A renewable resource, it requires less energy than most materials to process into finished products and is low-toxic and biodegradable. The key is to use this resource wisely--selecting wood from responsibly managed forests, substituting engineered wood and alternative materials where appropriate, reusing salvaged wood, and minimizing waste.

In this house, certified wood (from sustainably managed forests) and composite wood materials salvaged from normal lumber production were used for the framing, the cedar shingles and the numerous built-in bookcases and storage units. Alternatives to wood were selected for the flooring, and recycled wood was used as a design element in several locations. In addition, tiles made of recycled glass were used for the backsplash in the kitchen.

CONTENTS Certified wood
By absorbing and storing carbon dioxide, the world's forests play a key role in counteracting global warming. But the accelerating demand for lumber, fuel, and agricultural land worldwide is threatening the future of this valuable natural resource.

Certification programs are designed to help conserve, protect and restore the world's forests by encouraging companies to adopt ecologically sound forestry practices and by helping consumers identify and select timber products that come from well-managed forests. There are several certification systems to choose from, each with its own standards, assessment procedures, and method of certification. The Forest Certification Resource Center provides an overview of the four certification systems operating in the North American market and describes the strengths and weaknesses of each.

  • The American Tree Farm System is a program of the American Forest Foundation, an independent, nonprofit, nongovermental organization.

  • The Canadian Standards Association (CSA) is an independent nonprofit organization accredited by the Standards Council of Canada and operating according to nationally and internationally accepted standardization procedures and practices.

  • The Forest Stewardship Council (FSC) is an independent, nonprofit, nongovernmental organization promoting standards addressing environmental, social and economic issues.

  • The Sustainable Forestry Initiative (SFI) is a program of the American Forest & Paper Association, the national trade association for the U.S. forest products industry.
The new lumber used for this house--framing, door and window trim, built-in bookcases, storage units, cedar shingles--was FSC-certified. The cost was slightly higher than it would have been for standard lumber, and typically there were delays in obtaining certified materials.

Engineered lumber
A product created from small-diameter, fast-growing trees rather than old-growth timber, engineered lumber offers a practical substitute for solid wood framing. It turns small pieces of wood, combined with adhesives under heat and pressure, into strong, light, straight structural materials that typically achieve better structural characteristics than solid dimensional lumber.

The floor joists and structural beams and headers in this house are made from Trus Joist engineered lumber. This manufactured wood product is made of fibers from second- and third-growth timber and from nontraditional tree species such as aspen and poplar. The adhesive used to bind the wood fibers together is MDI (methyl diisocyanate) polyurethane. It contains no formaldehyde, so there should be no off-gassing after installation. It is highly toxic during the manufacturing process, however, so special pollution-control and health safeguards are required. For worker safety, the pressing process used to shape the wood product is remotely controlled, and the manufacturing plants meet stringent environmental standards.

Medium-Density Fiberboard (MDF)
One of the concerns associated with particleboard and fiberboard in the past has been urea formaldehyde offgassing. A new generation of board is now available that is made with phenolic resins that do not offgas formaldehyde, yet are stronger than their predecessors. Agricultural fiberboards often use MDI binders, which do not contain formaldehyde, and may be preferable for indoor air quality.

Flooring
Bamboo was used for the flooring in the main rooms of the house. Bamboo is a rapidly renewable resource. Unlike hardwood trees that require 40 or more years to mature, bamboo is a grass that matures in less than six years and is harvested over and over again from the same plant. It makes a highly durable floor covering, harder than oak and more dimensionally stable than maple.

There are two styles of bamboo to choose from as well as decisions about color and finish to be made.

  • Style -- With horizontal, or flat, grain flooring, the nodes of the bamboo are quite pronounced. With vertical grain flooring, the nodes are less visible, and the flooring is less "bamboo-looking."

  • Color and finish -- The flooring typically is available in two colors: natural, a light blond color similar to maple, and carmelized, a dark amber color. It can be ordered pre-finished or can be finished on site.

The owners selected unfinished, natural vertical grain flooring from TimberGrass LLC (now Teragren LLC). Installation of the six-foot lengths of tongue-and-groove bamboo strips was very similar to that of a traditional hardwood floor. The cost was slightly higher than for hardwood flooring.

Marmoleum from Forbo Linoleum Inc. was used for the flooring in the laundry room and back hallway. This moderately-priced linoleum product is made from natural, biodegradable materials and is installed with solvent-free adhesives. It is easy to clean and is very durable, making it a practical choice for utility areas.

Flooring for the entryway, mudroom, first floor bathroom and sunroom is Mankato limestone from Minnesota.

Recycled materials
kitchen backsplash The tiles for the backsplash in the kitchen are made of 100 percent recycled glass. Purchased from Bedrock Industries, they were more expensive than non-recycled glass tiles would have been.

Douglas fir, resawn from the ridge beam of the previous house on the site, was used for a structural post in the living room, for the mantel over the fireplace, and for the buffet in the dining area. Recycled redwood paneling was used as siding for the exercise pool in the basement.

Links and Resources

  • Green Building Products, published by Environmental Building News, is a comprehensive guide to environmentally preferred building products and materials. The process and criteria used to screen projects for the directory are described in the article What Makes a Product Green.
Website prepared by Eleanor Revelle and Ellen Galland.
Last updated: April 2007