Bamboo floors are manufactured from the bamboo plant. The majority of today's bamboo flooring products originate in China and other portions of Asia. The species of bamboo used for flooring is commonly known as "Moso".
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Bamboo is an attractive alternative for flooring because of its physical similarities to hardwoods. Bamboo floor manufacturers and sellers promote its strength, durability as well as resistance to insects and moisture while having the added benefit of being eco friendly. The hardness of bamboo ranges from 1180 (carbonized horizontal) to around 1380 (natural) using the Janka hardness test versus red oak (1290), white oak (1360), rock maple (1450), and hickory (1820),Brazilian Cherry / Jatoba (2350), (the higher the number the harder the material).[1]
Different forms of bamboo flooring exist. Each varies in its manufacturing process and differs largely based on economic viability and local preferences.
The most common form, particularly in southeast Asia, uses thin bamboo stems that are cut as flat as possible. They are cut to similar lengths and can be stained, varnished, or simply used as is. They are then nailed down to wooden beams or bigger pieces of bamboo stems. This form results in more space between each bamboo stem; flatness and tightness is not emphasized. This technique is usually used on stilted houses, resulting in better air circulation especially during the warmer summer months.
The manufactured bamboo flooring commonly found in North American markets is highly processed. Bamboo flooring is typically made by slicing mature bamboo poles or culms into strips. These culms are crosscut to length and then sliced into strips depending on the width desired. The outer skin and nodes are removed.[2] To remove starch and sugars the strips of bamboo are boiled in a solution of boric acid or lime. The bamboo is then dried and planed. Natural bamboo color is similar to beech wood. If a darker color similar to oak is desired, the bamboo goes through a carbonizing process of steaming under controlled pressure and heat. The carbonizing process can reduce the floor’s final hardness significantly compared to non-carbonized bamboo, rendering it softer than some pines and softer than more common red oak.
Most bamboo flooring uses a urea-formaldehyde (UF) adhesive in the lamination process. Though the use of UF resins, which emit volatile organic compounds (VOCs), is harmful to indoor air quality, bamboo flooring uses a relatively small amount compared with other materials, such as particleboards. Bamboo flooring products that avoid formaldehyde use are available, including some listed in the GreenSpec Directory.[3] The panels are then heat pressed to cure the adhesive. The cured boards are then planed, sanded, and milled. Finally an ultraviolet curing lacquer is applied to the boards.[2]
Manufactured bamboo floors are typically made available in planks with either vertical- or horizontal-grain orientation. In vertical bamboo floors, the component pieces are stood vertically on their narrowest edge and then press laminated side to side. The effect is a lined, almost uniform look to the surface of the finished floor plank. In horizontal bamboo floors, the slats are arranged in a horizontal direction, on their widest edge, and then joined side by side with adjacent pieces using a high-pressure laminate system. The characteristic nodes of the bamboo are visible on the finished horizontal surface.
Locking bamboo flooring is the easiest to install. Individual flooring planks have interlocking joints that click precisely into place. By combining plank alignment and color a lot of different styles can be produced.[4]
Bamboo has also gained a reputation as an eco-friendly, highly renewable source of material. Compared to wood it grows much faster because bamboo is a grass not a wood. Moso Bamboo is the primary species used for the manufacturing of flooring and plywood.[5] Moso bamboo can grow up to 47 inches in 24 hours and 78½ feet high in 40 to 50 days. It takes about 3–5 years for bamboo to reach full maturity.[6] Traditional hard woods can take 20 – 120 years to mature.[7]
Bamboo can be harvested without the need to replant because the root system is left intact when it is harvested. The rhizome root structure has the ability to hold the soil in place preventing erosion.[5] Rhizome root structures are horizontal stems that grow below the surface and help a plant reproduce vegetatively. Plants with rhizomes will colonize or spread laterally.[8] The Lacey Act recently strengthened the accountability in the sourcing of timber products. However enforcement is still in question.[5] Bamboo reaches maturity in five years which is the optimal age to harvest.[5] In a sustainably harvested forest only 20% of the forest is harvested annually allowing for 100% harvest in a five year period. In its natural environment it will need no irrigation, no pesticides, and no fertilizer. Bamboo has few pests so pesticides are not required. Bamboo certified to the standards of the Forest Stewardship Council (FSC) meets criteria for environmental sustainability and social responsibility, and several flooring products are available with this option.[3] Bamboo can sequester up to 70% more carbon per year than a hardwood forest.[5] All these factors keep the carbon footprint low.
Transportation of materials to a consumer is an often-overlooked factor in a carbon footprint. Since the majority of bamboo timber comes from China, it has to be shipped to the international destinations by boat and then by truck to vendors. A scientific study was conducted,[9] comparing the embodied energy - including transportation - of locally sourced USA concrete to bamboo flooring originating in China. This study assumes truck transportation of 500 mi (804 km) from the port of shipping. This portion of the transport accounts for 1645MJ of energy & 280 lb. CO2e towards the embodied energy and Carbon footprint of the bamboo flooring. In total the study indicates a total of 70% higher lb. CO2e and a 221% higher embodied energy for the bamboo flooring. This study chose the source of the bamboo flooring to be in Hunan Province in China and the destination to be in Denver, Colorado. As a result, the chosen source and destination in this study favored concrete above bamboo flooring. There are a number of bamboo flooring manufacturers that are based in ZheJiang & Jiangxi Provinces in China. In many cases the truck transport from these regions is less than 100 mi (160 km). The destination of the Bamboo flooring could also have been chosen to be closer to the coast. Should these factors have been compared in the study, the variance between the bamboo flooring & concrete would have been much lower, with the bamboo flooring, in certain conditions, performing better than the locally sourced concrete. In addition, should the study have been based on a Cradle to Cradle Design methodology, then the contributions of bamboo forests to sequestering Carbon, the "locking" of carbon in the bamboo flooring and the carbon cost of rehabilitation of the concrete mines would need to be factored into the study. A more encompassing and varied study will provide a more useful model for determining the true impact of transport on the Carbon footprint and embodied energy of bamboo flooring. The United States Green Building Council's LEED program allows points for the use of bamboo floors by virtue of it being a rapidly-renewable resource.
However, controversy exists over agricultural and manufacturing issues related to the production of bamboo floors, including the environmental effects of deforestation in order to plant bamboo[10] and the use of carcinogenic chemicals such as urea-formaldehyde in the glues used for lamination in some products.[11]
Some research has shown that bamboo may not be as environmentally friendly as it could be. The following are statements made in a report by Dr. Jim Boyer in a research paper for Dovetail partners.[10]
“Recently, bamboo expansion has come at the expense of natural forests, shrubs, and low-yield mixed plantations . . . It is common practice to cut down existing trees and replace them with bamboo.”
• “As forestlands tend to be in hilly and mountainous areas with steep slopes, clearcutting has resulted in an increase in erosion until the bamboo becomes fully established . . .”
• “Natural forests in the vicinity of bamboo plantations have sometimes given way to bamboo as a result of deliberate efforts to replace them or because of the vigorous natural expansion of bamboo in logged over forests. This process has also had a negative impact on biodiversity.”
• “The intensive management practices employed involve manual or chemical weeding and periodic tilling of the land to keep the soil clear of undergrowth. These practices increase erosion and result in single-species plantations over large areas.”
• “The intensive use of chemicals (pesticides, weed killers and fertilizers) [associated with growing bamboo] also affects the environment . . .”
Another green aspect of bamboo flooring that needs to be considered concerns the chemicals used in the manufacturing process. During the manufacturing of bamboo floors, some manufacturers use urea-formaldehyde as the adhesive for bonding the bamboo strips. According to the stringent CARB - California Air Resource Board standards there can be no more than 0.05 ppm (parts per million) of outgassed formaldehyde.[12] According to the USGBC’s LEED standard products with Urea-formaldehyde do not qualify for the EQ 4.4 Low-Emitting Products category.[13] Manufacturers are now offering formaldehyde-free bamboo flooring, but they can claim that they have “no added urea-formaldehyde” without providing substantial proof. Manufacturers may make use of equipment that may in itself be dangerous and polluting. Some manufacturers may require their products to be registered under International Organization for Standardization (ISO) standards 9001 for quality control and 14001 for environmental management systems EMS, although these standards are not necessarily very high.[3]