Color the Floor Green

Wood is a Sustainable Choice for Flooring

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Learning Objectives

Today, green initiatives are on the agendas of many corporations and governmental agencies, and global warming, it seems, is on the tip of everyone's tongue. Still, it is hotly debated as to whether the concept of sustainability has reached a "tipping point" in the public consciousness. For some audiences, such as interior designers, the answer is that sustainability can't be ignored. The push from consumers for environmentally friendly products means interior designers must be savvy about the choices they make when specifying the green materials they use. This CEU will explore the environmental impact of one material—wood—as it relates to flooring design choices.

The basis for understanding wood flooring choices is grounded in the cycle of tree growth. While it may seem like cutting down trees destroys forests and wreaks havoc on the environment, the reverse is actually true. Professionally managed hardwood forests in the United States and Canada are sustainably harvested, meaning that only a certain percentage of trees are removed annually, leaving the overall forest ecosystem intact.

Statistics show that the number of trees in existence today far exceeds those in the 1950s. In fact, the U.S. Forest Service, an agency of the Department of Agriculture, states that there were 98 percent more trees in 2002 than 1953. For every tree harvested in the United States, six more are planted in its place-and while it may take 40 to 50 years for those new trees to mature, wood from those trees won't be needed for another 50 to 100 years.

U.S. Forest Service data (2008) expands on these figures. For hardwoods in the Eastern United States, the average annual net growth was greater than average annual removals. In fact, the growth to removal ratio was calculated to be 1.66—indicating that wood volume is being added to inventory each year. Today's total standing volume of hardwoods is estimated to be 328 billion cubic feet.

A study by the National Association of Home Builders (NAHB) ranked the longevity of materials in homes. Wood floors were rated at more than 100 years, further legitimizing the notion that trees planted today will mature by 2057, but won't be needed until 2107. And during that time, trees contribute oxygen to the atmosphere while consuming carbon dioxide-a significant environmental plus.

According to a 2006 American Society of Interior Designers (ASID) member survey conducted by National Wood Flooring Association (NWFA), most interior designers consider wood floors to be environmentally friendly—a notion that has been recognized by key sustainability advocates and initiatives such as the U.S. Green Building Council's Leadership in Energy and Environmental Design (LEED®) program; the NAHB Model Green Home Building Guidelines; and the Green Building Initiative (GBI), which works to accelerate the adoption of building practices that result in energy efficient, healthier, and environmentally sustainable residential and commercial construction.

Strong, durable, and beautiful, wood floors are available in a wide variety of styles, species and colors.

Solid Wood Flooring—"Solid wood" flooring is made from a single piece of wood and comes in three basic types:

  • Strip flooring, which accounts for the majority of installations. Strips are usually are 2-1/4 inches wide, but also come in widths ranging from 1-1/2 inches to up to 3 inches.
  • Plank flooring, which involves boards that are more than 3 inches wide.
  • Parquet flooring, conducive to dramatic geometric effects, comes in standard patterns of 4-inch by 4-inch blocks, with specialty patterns ranging up to 36-inch square units.

The thickness of solid wood flooring can vary, but generally ranges from ¾ inch to 15/16 inch. One of the many benefits of solid wood flooring is that it can be sanded and refinished many times.

Engineered Wood Floors—are real wood floors that are manufactured using three to five layers of different wood veneers. The sub layers can be of the same species, or of different species. The grain of each layer runs in opposite directions, which makes it very stable. This means that the wood will expand and contract less than solid wood flooring during fluctuations in humidity and temperature. Engineered floors can be sanded and refinished, but not as many times as solid wood flooring.

Above: This custom parquet floor features solid maple with ebonized accent squares. The floor was finished on-site by Universal Floors in Washington, D.C., using a tung-oil surface finish. (larger image)
Below: American white oak, reclaimed and hand-crafted from old wine barrels, was installed on-site in random-width planks, using a water-based surface finish. The floor was installed by Fontenay in Corona del Mar, CA. (
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Surface finishes are durable, water-resistant and require minimal maintenance. Surface finishes are blends of synthetic resins. These finishes most often are referred to as urethanes or polyurethanes, and remain on the surface of the wood to form a protective coating.

The types of surface finishes available include: water-based, oil-based, conversion varnish, moisture-cured, acid-cured, and wax. An acrylic impregnated finish is another type of finish that is injected into the wood to create a super hard, extremely durable floor and is primarily used in commercial applications.

Hardwood floors can be finished on-site or prefinished in a factory. Many designers prefer the rich, consistent look of flooring finished on-site, but it requires on-site sanding, proper cleaning, multiple coats of finish, and can tie up a work site for several days. The alternative is a factory-applied finish which typically involves at least four coats of ultraviolet-cured urethane resin applied under strict controls at the factory—a process that may add consistency and durability. Installation is "straight out of the box," which can make the job easier and faster.

Designers and their clients are getting more adept at using hardwoods. In 2006, 85 percent of interior designers indicated that their clients are "very" to "somewhat" knowledgeable about wood flooring—compared to 67 percent in 1993—a significant shift in 13 years. Although oak is still preferred by a majority of interior designers, recently its preference has waned. In 2006, 55 percent of designers preferred oak—down significantly from 67 percent in 1993. Preference for cherry, walnut, maple and mahogany have also increased since the previous study, which suggests that designers are now more aware of these other options. In terms of style, plank flooring took the lead from strip flooring since 1993 (nearly half preferred plank in 2006); however, among interior designers who have been in the industry for several decades, strip is still preferred over plank.

Designers are also favoring medium and dark tones, as preference for natural and white tones has decreased, at least among senior designers. More experienced designers—those who have been in the industry more than 11 years—prefer medium tones by a wide margin. (Note: medium tones can be natural). Other findings of note: Four in 10 interior designers indicated that the living room was the most popular room for wood floors followed by the great room/den; and more than half of designers surveyed saw increased demand for antique or reclaimed wood flooring in the past two years (this number more than doubled since 1993).

Besides their environmental and aesthetic benefits, hardwood floors are a good financial investment and increase the value of a property. Wood floors are often cited in a sales pitch, and have been known to spur faster sales and higher prices according to an NWFA survey among licensed U.S. real estate agents and brokers. In 2006, 99 percent of real estate professionals indicated that having hardwood floors "greatly" or "somewhat" influenced a home's salability to some extent. In addition, nine out of 10 respondents suggested that homes with mostly hardwood floors will sell for more money and faster—an increase over the 1993 study when 82 percent of respondents felt this way.

Unlike other flooring alternatives, which can harbor allergy-generating mold, mildew, and dust mites, hardwood floors may actually improve a structure's indoor air quality (IAQ). With wood floors, there is no place for mold, pollen and animal dander to grow. Hardwood flooring has long been considered an excellent choice for anyone with any kind of environmental allergies and is recommended by many doctors as a key step in creating a healthy home. As the U.S. Environmental Protection Agency (EPA) cites, especially for people with asthma or breathing problems, IAQ will be better with wood floors.

Commenting on IAQ in residential settings, Paula Baker-Laporte, AIA, principal and owner of Baker-Laporte and Assoc., Sante Fe, NM, considers two groups of people when designing a healthy home: the chemically sensitive, and those whose priority is a healthful space.

"For people who are very chemically sensitive, I recommend a factory UV-floor finish so that they don't have to refinish in their home. Pre-finished materials are offgassed under controlled conditions and the client receives an inert product," explains Baker-Laporte. "In the case of healthy people without chemical sensitivities, there are many low- or zero-VOC finishes that work within the parameters of healthy design."

When it comes to a project's sustainability, non-toxic care and cleaning of wood products is an important Consideration. Wood floors are among the easiest floors to keep clean, particularly those with urethane finishes. For the most part, they can be maintained with simple, routine cleaning measures such as sweeping with a soft bristle broom or dry mopping.

The usual damage to a wood floor comes from debris. Dirt, dust, and grit can dull a floor's finish and cause scratches that can only be repaired by refinishing. Vacuums with beater bars can cause dents in the floor's finish and should not be used; nor should warm soapy water be used to clean hardwood floors because the soap may leave a film that could become slippery or even damage the finish.

Regardless of its finish, a wood floor will quickly lose its luster if exposed to excessive water, and may even warp. Middlebury College in Vermont initially had concerns about putting a wood floor in a dining hall, with its repeated exposure to water and daily damp mopping. Yet the floor holds up well, according to Mark Gleason, the college's construction project manager. "The hall serves anywhere from 700 to 900 kids for dinner each day, so it gets a great deal of use. It still looks great," he says. Once yearly, the floor is buffed down to a bare wood and a low-VOC, water-based sealer is applied to restore the floor's luster.

Another concern is ultraviolet radiation in sunlight which can cause discoloration over time. The same ultraviolet rays that can burn and age skin will also affect any organic material, including wood. Prolonged exposure to sunlight will change the color of virtually any wood floor, regardless of the species or finish. Some woods lighten when exposed to sunlight. Others, like cherry and oak, tend to darken. Some finishes feature sunscreens to help block the penetration of ultraviolet rays, extending the time it will take the wood to change color.

For a modern, organic feel, Gabrielle Meaney of New Detroit Design Studio in Ray, MI, created a nautilus-patterned parquet floor for a spiral staircase in padauk, purpleheart and curly maple. The stairs were then sanded and finished with a satin oil-based finish. (
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Consumers are increasingly choosing wood for its health benefits and ease of maintenance. The NWFA realtor survey attests to the fact that as consumers become savvier about the benefits of hardwood flooring, their rationale for wanting them has changed. The key reasons homebuyers like hardwood floors has shifted since 1993. Now, realtors say that resale value, fewer allergic reactions, and beauty/modern/trendy looking aesthetics are the major reasons consumers desire wood floors. Today's hardwood floors are considered "easy to care for" by 66 percent of these real estate professionals (in 2006)—higher than in 1993, when only 57 percent considered them so. And hardwood flooring can become a habit. Realtors say that clients who have lived in homes with hardwood floors are more likely to buy another home with hardwood floors (84 percent vs. 69 percent in 1993—a significant shift).

Clients are well aware that all hardwoods are sustainable and renewable. Yet many will press designers further for the species that is the "greenest" of the green. The following types come with sterling environmental credentials:

  • Reclaimed flooring—Wood from old barns, buildings, lofts, rural structures and sustainable sources of reclaimed timber are an ideal choice for green flooring while making a home beautiful and unique.
  • Cork—Elegant and eye-catching with its color and texture, cork flooring contains a substance called suberin that makes the cork resistant to mold, mildew and germs. The bark of the tree is harvested and new bark grows back without harming the tree.
  • Bamboo—Actually a grass, bamboo used in flooring grows in the Southern part of China. This plant grows quickly and matures in five to seven years. Beacause installation is slightly different than that of hardwoods, it is important to hire an experienced installer.

When working with exotic or foreign species, a note of caution is in order. It is a safe bet that a domestic hardwood species came from a sustainably harvested forest—but sustainability isn't a fait accompli for all imports. It's often difficult to know the source of the wood harvested from overseas, where many areas have experienced illegal logging. Where does the wood come from? Was it harvested legally and responsibly? Is the supplier involved in a certification system? These are some of the initial questions to determine the sustainability quotient of tropical or exotic species.

Another major consideration for determining wood flooring's "green" benefit is the product's Volatile Organic Compound (VOC) content, which is determined by the solvents used in finishes and adhesives. As the EPA considers architectural coatings—including wood finishes—second only to cars in producing VOC emissions, VOC laws, particularly in California and the Northeast, have become stricter. As a result, some manufacturers have reformulated their products with lower VOCs. Designers can choose from waterborne finishes that tend to have the lowest VOC levels, and several no-VOC or solvent-free adhesives and finishes that are available on the market. Because allowable VOC content can vary by region, the best policy is always to check the local VOC laws and ask the manufacturer to assure that the finish and adhesive is legally compliant and works with the flooring selected.

  For the design of his showroom, John Yarema of Johnson Yarema Hardwood Floors in Troy, MI, chose a mix of wenge, quarter-sawn white oak, quartered maple and quarter-sawn walnut to add depth and create a three-dimensional effect, with custom parquet. (larger image)

A growing area of research is aimed at measuring the environmental impacts associated with products and processes in daily use. This life-cycle thinking scientifically documents the collective inputs and outputs associated with the production and use of commercial products.

Research related to solid hardwood flooring indicates that solid wood is a desirable floor covering from an environmental impact standpoint—a finding consistent with previous studies in Europe. Preliminary results of the 2008 Consortium for Research on Renewable Industrial Materials (CORRIM) study indicate that solid hardwood is preferable as a flooring option from an environmental standpoint when compared to tile, linoleum, and both nylon and wool carpet. In addition to the carbon-neutral benefits associated with wood, hardwood floors showed benign air emissions. Substantially less water and total primary energy is required to produce wood flooring. Solid wood also has a longer service life and desirable end-of-life scenarios. In fact, solid hardwood flooring does not assume complete disposal in a landfill after service life; it can be recycled or combusted as wood fuel representing an advantage to the environment over other disposal scenarios.

In other research, the Athena Model, developed by the nonprofit Athena Sustainable Materials Institute, compares the cradle-to-grave ecological quotient of wood, steel and concrete. Wood was found to have the lowest environmental impact, and to exceed the other materials in terms of environmental soundness as measured by energy use; production of greenhouse gases; air and water pollution; production of solid waste; and overall ecological resource use.

The NWFA has begun the process of a similar life-cycle analysis for engineered wood floors; findings are scheduled to be available in 2009.

Wood flooring is a proven sustainable choice for green design. Durable, renewable hardwoods will look as good now as they will in 10, 20, and in some cases, 100 years. Known for their warmth and beauty, wood floors give a humanizing touch to any setting, and their versatility enables a range of looks from formal to modern. With eco-sensitive finishes, adhesives and cleaning products, wood floors are a fundamental component to the sustainability of any structure.

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Learning Objectives:

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Interiors & Sources' Continuing Education Series articles allow design practitioners to earn continuing education unit credits through the pages of the magazine and on our web site. Use the following learning objectives to focus your study while reading this issue's article.

After reading this article, you should be able to:

  • Identify the financial, health, and environmental benefits associated with wood floors.
  • Explain the characteristics of an engineered wood floor.
  • Determine the reasons and applications for which wood flooring is commonly specified.

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Regardless of the style or finishing method, wood flooring adds warmth and beauty to a space and is adaptable to any decor. This floor features solid maple and steamed walnut strip. Hammer Hardwood Floors in Perry, Iowa, installed the floor on-site using a water-based surface finish. (larger image)