Bamboo Flooring
Eco Friendly Bamboo Flooring: Not All Bamboo is Equal
Bamboo is proving to be a durable and attractive alternative to hardwoods for flooring. It is rapidly renewable, growing to maturity in five to seven years, compared to 50-150 years for many hardwoods. It is sturdy, with a hardness that rivals and in some cases exceeds the hardness of hardwoods. Bamboo is attractive and readily available in solid, woven and engineered versions. It offers a variety of colors and grains and it is cost effective, often being less expensive than hardwoods and just as easy to install.
The
surge in popularity of bamboo as an eco-friendly flooring material
has created a rush to market with a simultaneous surge in manufacturing
capacity. The rapid growth has resulted in a wide range of quality
of the finished product, depending on the manufacturing processes
used. There are a number of manufacturing variables that determine
the ultimate quality of bamboo flooring. These include processing
time, moisture content, density level, the adhesives that are used
to manufacture the end product, and the quality of the surface coating.
Processing time is extremely important. The stalks should be processed quickly after cutting. If they are not processed promptly, they can develop a surface mold that is often visible in the finished product. Quality manufacturers process their cut stalks immediately, thus eliminating the possibility of mold.
Moisture content is also imperative and in general it should be as low as possible at the time of manufacture. It can vary widely, from 7% to 14%, and many Bamboo flooring mills ship material that has only been dried to 9-12%, which is not adequate in many climate regions. With Woven Bamboo, in particular, the drying process is essential. If Woven Bamboo is manufactured to 9-12% moisture content and then installed in a dry climate area, it has a tendency to crack or develop ripples on the plank face. For installations in areas where relative humidity drops below 35%, material that has been well-dried at the factory is essential. All EcoTimber Bamboo flooring is dried to 6-8% moisture content, making it ideal for use in a wide range of climates.s.
Types of Bamboo Flooring
Bamboo flooring comes in a variety of types. The three most common styles in the marketplace are solid, woven (strand) and engineered bamboo flooring.
Solid bamboo flooring
Solid bamboo flooring bears its name because it is made up of pieces of solid Bamboo. This distinguishes it from engineered Bamboo, which combines Bamboo wear layers with wood cores and backs. It also differentiates the solid Bamboo from woven or strand Bamboo which is made of shredded bamboo fibers. In actuality, “solid” Bamboo flooring is made up of small strips of Bamboo that are glued together to form the finished product.
Woven bamboo flooring
Woven Bamboo flooring is also known as strand or strandwoven Bamboo. Woven Bamboo results from a fundamentally different manufacturing process than the one used for solid Bamboo flooring. In this process, the timber Bamboo is shredded into fibers, which are then mixed with resin and compressed into solid blocks that are then cut into planks to be milled to a standard flooring profile. Woven Bamboo is much harder and denser than traditional Bamboo flooring (about 3000 on the Janka scale), making it well suited for high-traffic areas. The hardness results from the resin that is used and the density achieved by pressing the fibers tightly together.
The adhesives that are used are a critical factor in determining the quality of a finished product. Low quality adhesives, especially those containing urea-formaldehyde, can emit harmful chemicals in the home and should be avoided. Higher quality adhesives eliminate these problems. EcoTimber Solid Bamboo is made with a top-quality formaldehyde-free European adhesive, and EcoTimber Woven Bamboo is made with a proprietary phenolic resin that contains no urea-formaldehyde.
Engineered Bamboo flooring
Traditional (horizontal and vertical) engineered Bamboo flooring faces some issues with reliability. Because it is laminated to a cross-ply core, the top layer of an engineered traditional Bamboo floor does not have the ability to shrink when the floor is exposed to dry air, causing stresses to develop within the plank. With most hardwoods, the natural bonding material (lignen) that holds the fibers together is strong enough to withstand these stresses and resist cracking. With Bamboo, although the fibers are very strong, the natural bonding material between them is relatively weak, making the top layer of a traditional engineered Bamboo floor more susceptible to cracking under dry conditions than most engineered hardwoods. At EcoTimber, we no longer offer traditional engineered Bamboo flooring because we feel that no matter how carefully it is manufactured, the biology of Bamboo makes this format unreliable in many areas of the country.
However, using our proprietary glue mixture and curing process, along with careful drying techniques, EcoTimber has overcome this problem with its Engineered Woven Bamboo. We did years of research and development to create a strandwoven material that is highly crack-resistant, far more so than traditional Bamboo and more so than many hardwoods. Not all strandwoven Bamboo products can make this claim!
Through our extensive testing, we also found that we can eliminate some of the stresses that develop in the top layer of an engineered Bamboo floor by using Bamboo as the middle cross-ply layer. Unlike wood, Bamboo shrinks somewhat along its length in response to dry conditions, thus alleviating some of the tension that develops between the top two layers under dry conditions. Our Engineered Woven Bamboo features a 6mm-thick cross-ply Bamboo core.
EcoTimber has also maximized the stability and warp-resistance of its Engineered Woven Bamboo by incorporating a Woven Bamboo backing layer of the same thickness as the top layer (4mm). This creates perfect balance, so that the top and bottom layers expand and contract at the same rate, helping to keep the plank flat as moisture levels change.
Bamboo Hardness: Fact & Fiction
The Janka test
can give misleading information about bamboo’s durability as a flooring
product. Because of the strength of the Bamboo fibers, the floor
resists impact with round objects like the steel balls used in Janka
tests. The fibers act like a trampoline and bounce the steel ball
out. However, as noted, the bonding material between the Bamboo
fibers is much weaker than the lignens in wood. If a sharp object
such as a rock in someone’s shoe cuts the Bamboo fibers, the Bamboo
scratches or gouges easily because the material between the fibers
is relatively soft. Therefore, if a Bamboo floor and a hardwood
floor have identical Janka test ratings, in reality the hardwood
floor will dent and scratch less than the Bamboo. It is also important
to note that some Bamboo flooring companies report very misleading
Janka test ratings. They get high ratings by performing the test
on the ‘knuckle’ or node of the Bamboo stalk, which occupies only
a tiny portion of the floor’s surface area and is substantially
harder than most of the floor.
Traditional Bamboo flooring has Janka ratings of 1300-1600 PSI for
the Natural color, and 1100-1300 for the Carbonized (‘Amber’) color.
The inherent hardness, combined with a tough finish (often acrylic),
makes Bamboo a durable choice for flooring, but the hardness of
traditional Bamboo flooring has been greatly exaggerated by some
manufacturers. Woven Bamboo, on the other hand, rivals the hardness
of the most dense tropical hardwoods. EcoTimber Woven Bamboo flooring
is 3000 on the Janka Scale of hardness, harder than Brazilian Cherry
(Jatoba), which is rated at 2800.