The Green Thumb: Bamboo U, Part Three
July 30, 2007
In parts one and two, we saw how bamboo is used worldwide for many purposes including: food, medicine, soil stabilizer, pulp (for manufacturing paper) and as a building material. We also discussed what bamboo is (a primitive grass; not a wood species as is commonly believed) and how it derives its great strength rivaling both steel; in tension, and concrete; in compression. This month, we’ll conclude this series with a look at how bamboo is being used as a building material around the world and at home.
The Right StuffBamboo’s dimensional stability, rapid growth and its hardy nature make it an ideal “green” building Product (not to mention its great strength and hardness). In North America, bamboo is used primarily as a building material for flooring and plywood panels. Mainly, bamboo has found its place as a contender in the hardwood flooring market here in North America in the past decade, moving from a niche market to mainstream.
In North America, bamboo is used primarily as a building material for flooring and plywood panels. Mainly, bamboo has found its place as a contender in the hardwood flooring market here in North America in the past decade, moving from a niche market to mainstream.
Presidential AppealIn an article entitled: “Hail to the (Former) Chief,” (August 2005), we discussed how the William Jefferson Clinton Presidential Library & Center in Little Rock, Ark., achieved silver LEED (Leadership in Energy & Environmental Design) certification. One of the ways it did so was by using bamboo flooring throughout the main building. Bamboo’s rapid growth earns it credits/points under LEED Material & Resources (MR) criteria and so too its ability to be harvested without harming the plant itself thus making it non eco-disruptive.
Under FootToday, about 45 million cubic feet of bamboo flooring is sold in North America by about 200 companies, up from eight companies in 1997. This is about 2 percent to 3 percent of the market. Essentially, there are three types of bamboo flooring sold:
• Solid: strips of distinct layers of bamboo.
• Engineered: bamboo top surface layer bonded to other materials.
• Strand: separates bamboo into individual fibers and binds them under heat and pressure without a PF (phenol formaldehyde) resin.
Real Blond?Bamboo’s natural coloration is a light blond, but it can be stained to match cherry and fruitwood. A darker hue or amber color is achieved by pressure steaming which caramelizes the sugar present in the bamboo.
House of BambooIn 2000, the ICBO (International Conference of Building Officials) passed AC162: Acceptance Criteria for Structural Bamboo. This document provides engineers and architects with formulas and test criteria for the structural use of all species of bamboo. Until this action by the ICBO, the lack of internationally recognized standards has been an impediment to the use of structural bamboo.
However, structural bamboo has been a tough sell in the North American market for various reasons. First and foremost is the need for thick insulation; typically batts, in wall and roof cavities. In this regard, wood framing is superior since bamboo poles are of a thinner dimension. Where insulation is not a critical factor, such as a tropical climate, bamboo works well and is typically accepted by code officials pursuant to the ICBO technical criteria outlined in AC162.
Only in Hawaii has bamboo been used effectively as a structural material. Another factor is labor costs. Bamboo requires great attention to detail, thus making it more labor intensive and more expensive than traditional dimensional lumber. In developing countries, labor costs are minimal as compared to North America, contributing to its widespread use for framing structures.
Ply BambooIn the 1990s, much experimenting and research was going on concerning the use of bamboo for interior finish materials. Leading this effort is the use of bamboo as a replacement for plywood. One leading company, Teregren, manufactures panels and veneers made from bamboo for use in the manufacture of:
• Traditional wood products
The manufacturing process includes the use of a low off-gassing formaldehyde binder and earns points under LEED MR (Materials & Resources):
• Credit 4: Low Emitting Materials
• Credit 6: Rapidly Renewable Materials
Under the auspices of the ISO (International Standards Organization), ply bamboo manufacturers can be registered pursuant to ISO:
• 9001: Quality Control
• 14001: Environmental Management Systems (EMS)
ISO 14001 requires site visits for confirmation and accreditation by ISO auditors. The Chinese government believes such auditors from both Europe and North America restrict their market access so they are accrediting their own registrars. This may be problematic since ISO 9001 and 14001 are commonly recognized as a prerequisite for supplying European and North American markets.
Bamboo & LEEDBamboo has very little naturally occurring formaldehyde in comparison to hardwood species. UF binders, when used, are based on the more stringent European rather than NA standards for emission limits. All bamboo strand flooring made with PF (Phenol Formaldehyde) meet LEED IEQ (Indoor Environmental Quality) credit criteria for low-emitting composite materials.
The NAF binder used for bamboo flooring is the same as is used for Ag (Agricultural) fiber panel products: Isocyanate resin. Though it does not contain the carcinogen formaldehyde, Isocyanate is highly reactive and presents a danger to workers in the manufacturing facility. Preservative treatments for bamboo triple its cost and range from mild (smoke and boric acid) to toxic (arsenic and copper compounds). Bamboo used locally is hardly ever treated with preservatives, whereas exports to Europe and NA are preservative treated. However, bamboo flooring is rarely preservative treated.
Growing RecognitionIn some forests in Asia and South America where bamboo is grown alongside wood, bamboo is being certified as a green building product. Though it has the potential to be certified per FSC (Forest Stewardship Council) standards, to date, it has not been. In May 2004, the FSC issued a “Guidance Notice” promising to provide bamboo plantations with a set of standards by which to grow bamboo in an environmentally responsible manner.
In China, the main producer of bamboo, “green labels” have been awarded to counties for environmentally responsible growing of bamboo. In Chinese culture, such awards hold great prestige and symbolism thus encouraging mimicking.
In the years ahead, expect to see more and more bamboo-based building products in the North American market. With so many advantages as a green building product, it is inevitable that bamboo will find its place among the very best of environmentally responsible/sustainable building materials.