Using Suitable Green Materials

Claudette Reichel  |  6/20/2008 12:08:24 AM

Figure 1, Finger Joint Studs

Figure 2, LSL Studs

Using environmentally friendly, or “green” materials, curbs depletion of natural resources and pollution. Demand for green is growing — with more product choices each year. Green materials have some or all of these attributes, the more the better:

  • Renewable (made of materials that are readily renewable, like fast-growing trees and agricultural products)
  • Durable (long service life with little maintenance)
  • Energy-saving (or energy producing via clean, renewable sources)
  • Low embodied energy (the energy required to extract, process, package, transport, install and dispose of or recycle the material)
  • Promotes good air quality, both indoor and environmental
  • Low impact on water resources, both quality and supply
  • Low impact on the ecosystem and the earth’s protective ozone layer
  • Recycled content or was salvaged for re-use
  • Reusable or recyclable (can be feasibly separated and used again as is or in making something else)

Examine the performance properties along with the environmental advantages of any material. Various green labeling, product directories and certification programs are appearing, such as GreenSpec, Green Seal, Cradle-to-Cradle, GreenHomeGuide, Forest Stewardship Council, Sustainable Forestry Initiative and others.

Some widely available green home building material options include:

Foundation: Concrete produced from a mix of fly ash and slag (recycled industrial waste products) with cement has many advantages. The three-way mix costs less, uses recycled material and substantially enhances concrete performance by producing higher long term strength, increased workability with less water and reduced efflorescence and permeability.

Framing: Green structural alternatives include:

  • Engineered lumber (laminated strand lumber, wood I-beam, finger joint studs, OSB, etc.) is made from small pieces of wood combined with adhesives to produce high-performance alternatives to 2x10 or larger solid wood framing (often derived from old growth forests) in headers, beams, joists for floors and ceilings are straight and true alternatives to solid wood studs. Engineered beams and joists can handle higher loads, longer spans, and provide squeak-free floors. Engineered studs eliminate the typical waste factor due to warpage and flaws while providing straight and precise walls, even with high ceilings. (Figure 1, Finger Joint Studs and Figure 2, LSL Studs)
  • Wood sheathing and subfloor panels made with formaldehyde-free resins protect workers from the health hazards of off-gassing and dust.
  • High-performance building systems such as structural insulated panels (SIPS) insulated concrete form systems (ICF), shotcrete ISPS, and Optimum Value Engineered (OVE) framing systems are highly energy-efficient, low-waste options. Steel framing is at least 20% recycled, 100% recyclable and low-waste.
  • Wood frame building systems have the lowest “embodied energy” (the energy used to make and supply the product), when compared to steel and concrete. Borate-treated wood is non-toxic to people and the environment with good durability through its resistance to insects, fungi and decay.
  • Use lumber and wood products certified for sustainable forest management, such as the Forest Stewardship Council (FSC) or Sustainable Forestry Initiative certification, to support environmentally responsible forestry.

Insulation: In general, any insulation product that saves energy without causing harm is a green material. This is particularly so for materials that create high whole wall R-values, reduce air leakage and currents, or have other advantages. Some insulation materials with additional green properties include:

  • Cellulose insulation is made from up to 80% recycled newsprint with fire retardants and binders. The most common fire retardant is boric acid, a low-toxic treatment that can provide protection from insect and fungi infestation. Products with borate levels high enough to be registered as an insecticide are available and may provide added protection from termites and fungi.
  • CFC/HCFC-free spray foams provide superior air sealing and rigid foam boards provide high R-value and spanning capability for unbroken coverage without damaging the earth’s ozone layer. Today’s closed-cell polyurethane foams no longer use CFCs as the blowing agent and have an aged R-value of 5.6 - 6.5/inch (less than with CFCs, but still high). Open cell low-density foams have a lower R-value (3.6/inch), but are flexible and tend to maintain their seal as buildings shift over time. Some use carbon dioxide as the blowing agent, which poses no harm to either the environment or the occupants when it outgases. Soybean and sugar cane-based spray foam is now available, reducing use of non-renewable petroleum based components
  • Recycled content mineral wool insulations include some fiberglass products with recycled glass content, formaldehyde-free binders and slag wool products made from steel mill waste.
  • Cotton insulation (R-3/inch) is made from recycled denim fabric scraps.
  • Precast autoclaved cellular concrete (ACC), a lightweight insulating concrete, is similar to AAC, but is made with a waste product, such as fly ash, in place of high-silica sand.

Siding: Options with varying green characteristics include:

  • Fiber-cement siding and trim contains cement and wood fiber. It is durable, impact resistant, noncombustible, termite resistant, low maintenance and economical.
  • Aluminum siding can have a high recycled-content and is recyclable. Although aluminum has a high embodied energy initially, it drops considerably when recycled.
  • Some vinyl sidings have recycled content from industrial scrap, require no finishes, little maintenance, and low cost. High quality products are damage resistant and long lasting.
  • Engineered and composite wood sidings are resource efficient, yet vary widely in durability and weather resistance. Careful selection and finishes are needed.
  • Salvaged old bricks are a durable, reusable material with high market appeal.

Roofing: Since roofing is such a bulky waste material, longevity is a high priority for green roofing material options:

  • Metal roofing is durable, low maintenance, can contain up to 100% recycled content and is usually recyclable, so it does not create a waste burden like short-lived composition shingles. A light color or heat-reflective “cool color” coating makes it an energy-saving feature. Snap lock standing seam metal roofing is relatively expensive, but is more leak resistant than less expensive types of residential metal roofing with exposed fasteners that tend to loosen over time and need to be secured periodically.
  • Fiber-cement composite roofing tiles or shakes are durable, recyclable, and less expensive than other long-lasting roofings and are a good choice in a hot climate (but may not perform well in freeze-thaw climates).
  • Tile and slate are very long lasting and easy to maintain, but expensive and heavy (needing extra structural support and higher transportation costs). Light-colored and curved ventilated tiles (installed on battens with vented or no bird-stops) have energy-saving benefits. Concrete tile is more impact resistant and less expensive than clay.
  • Recycled-content organic asphalt shingles contain recycled waste paper or mineral slag. They have similar characteristics as fiberglass shingles: low cost, light weight, similar warranties and a short lifespan.
  • High-wind rated shingles are resistant to wind damage, greatly reducing the waste created by storms.
  • Cool color shingles, a new technology, have energy-saving heat reflective granules that also extend the life of the fiberglass shingles.

Recycled plastic lumber: 100% plastic lumber is typically made from recycled plastics; composite lumber may combine recycled plastic with waste wood fibers. It is used for decking, fencing, exterior trim and other uses, but not structural support. It generally has low moisture absorption and high resistance to decay, insects and UV damage so it is durable, but some composites have a tendency to mildew. It requires less maintenance than wood decking and needs no refinishing, although many composites weather to a gray color. Composites have more stability than solid plastics. Technology advancements are improving performance and reducing cost. Use stainless steel or hidden fastener systems to avoid stains from hardware rust.

Flooring: Green floor finish options include:

  • Green label, low VOC carpets have met the Carpet and Rug Institute testing standards for low emissions of volatile organic compounds. Recycled-content carpet contains polyester fibers made from recycled plastics (such as soda bottles). Some nylon carpets also use recycled content in their face fibers or backings. Recyclable carpet and replaceable carpet squares reduce bulky carpet waste to landfills. Natural fiber carpets, such as wool, sisal, jute, sea grass or coir, are made from renewable or plentiful resources and are low in embodied energy and pollution impacts. Carpet can be installed without adhesives, but can harbor dirt, dust mites and other contaminants that are difficult to remove.
  • Wood, bamboo and cork floorings are made from renewable materials, are long lasting, can be restored when scratched, and are reusable. Bamboo and cork are rapidly renewable, and are becoming widely available. Bamboo is extremely hard and durable. Cork has excellent acoustic qualities. Protective finishes must be maintained; look for low VOC products.
  • Natural linoleum is made from natural linseed oil, rosins and wood flour with a jute backing. Over time it becomes harder and more durable, and has a very long life span.
  • Rubber flooring is made from a renewable resource, often has recycled content, is easy to maintain, has a long life span, is comfortable for standing, flood resistant, and can be installed without adhesive. Since it tends to off-gas, it is best used outdoors or in well ventilated indoor areas.
  • Porcelain tile is an extremely durable flooring, and more impact resistant than ceramic tile. Recycled-content porcelain and ceramic tiles that contain recycled glass, ceramics or other materials are increasingly available, yet tend to cost more. Tile is recyclable, low maintenance and flood resistant.
  • Decorative concrete eliminates the need for, and later disposal of, a floor covering material on a slab foundation and is flood resistant. However, protective finishes must be maintained to prevent scratching and staining; seek low VOC sealers and finishes.

Finishes: Interior and exterior finish materials and coatings with green properties include:

  • Low-VOC paints, wood finishes, adhesives and sealants contain little or no solvents, so they have little odor and low emission of volatile organic compounds (potentially harmful air contaminants).
  • Recycled content interior panels (medium density fiberboard or MDF) for millwork, cabinetry and paneling can be made from corrugated boxes, newsprint and agricultural wastes (bagasse, straw, wheat, soy). Some MDF materials are also formaldehyde-free.
  • Finger-jointed trim is made from short lengths of scrap lumber, suitable for painted trim.
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