As the focus on environmental responsibility gains strength among consumers and the wood flooring industry, bamboo flooring continues to be in the spotlight. Love it or hate it, it's something most contractors will have to deal with sooner or later. Of course, bamboo is technically a grass. "Solid" bamboo is constructed of rectangles of bamboo glued together, either horizontally or vertically. Engineered bamboo is constructed like any engineered floor, with wood layers below a bamboo wear layer. The newest type of bamboo construction is strand-woven, a process in which bamboo strands are saturated with an adhesive and fused together under enormous pressure, resulting in a product much harder than traditional bamboo flooring. Bamboo can be a great floor, but there are some caveats to take into consideration. Following are some things I wish every customer would understand about bamboo. (These are general guidelines; always follow the manufacturers' directions for the specific product you are installing).

1) Let it Expand

Many installers are in the habit of leaving expansion at the sides of boards but not at the ends. That's usually fine for a typical hardwood floor, but bamboo does expand and contract along its length. Horizontal solid bamboo will expand and contract more than vertical bamboo, and strand-woven bamboo will expand and contract just like solid wood flooring.

2) Understand Janka

People should have realistic expectations of how a bamboo floor will perform. Sometimes the Janka numbers lead people to think a bamboo floor will be more durable than it actually is in real-life situations. Bamboo fibers are strong, but the lignins bonding them together are weak. In a Janka test, a smooth, round ball is pressed into the material. With bamboo, the fibers are springy and tend to resist the ball. However, if you hit bamboo with a sharp object—like a stiletto heel or a small rock in the sole of your shoe—it will cut into a bamboo floor more than it would in an oak floor. An exception to this is strand-woven bamboo, for which Janka tests accurately predict performance.


RELATED: Beyond Bamboo Basics: Gain a Deeper Understanding of this Flooring


3) Watch The RH

With engineered products, it's important to keep bamboo's biological structure—strong fibers and weak bonding material between them—in mind. When a bamboo wear layer is exposed to very low relative humidity (RH), the fibers want to shrink and pull away from each other, but the fibers are held in place by the cross-ply structure of the engineered product, so they can't move. The weak bonding lignins can then break, creating cracks in the wear layer. If there's a situation where the RH is likely to get very low, well-acclimated solid bamboo may be a safer option.

4) Measure MC Accurately

Make sure the manufacturer of your moisture meter has done the proper testing for bamboo so you know what the correct adjustment is on your moisture meter. If you're using a pin meter, as you poke into the floor, make sure the prongs don't cross a glue line of the little rectangles glued together to form the floor, because you'll get a faulty reading. When you're buying bamboo, look for kiln drying that meets typical American standards: within 6 to 8 percent moisture content (MC). Lots of product coming in from overseas is imported with a MC of up to 12 percent.

5) Acclimate as Necessary

Because solid bamboo flooring is made up of lots of little pieces of bamboo glued together, people often assume it doesn't need to be acclimated to the job site. Not true—even though there are many small pieces, they are all oriented in the same direction and will expand and contract. Solid bamboo flooring tends to acclimate quickly (three to seven days is typical), but is does need to acclimate. Strand-woven bamboo also requires acclimation, and it acclimates very slowly. In extreme climates, it can take up to 30 days for a strand-woven bamboo floor to acclimate to a job site. As with most engineered products of any species, engineered bamboo may not require acclimation (check with the manufacturer).


RELATED: Avoid Common Callbacks with Imported Species


6) Know Your LEED Points

With the LEED (Leadership in Energy and Environmental Design) certification system, products may garner points under different categories. Under the "Rapidly Renewable Materials" credit, any solid and strand-woven bamboo flooring earns points, but engineered bamboo does not, since it contains wood. Under the "Certified Wood" credit, bamboo flooring may earn points if it is FSC (Forest Stewardship Council)-certified, but the value of FSC-certified bamboo cannot be applied to both the "Certified Wood" and "Rapidly Renewable" credits—you have to choose one.

Another credit rewards products with no added urea-formaldehyde. Traditionally, the adhesives used to glue bamboo flooring together have been urea-formaldehyde adhesives, which tend to off-gas long after being installed in a customer's home. Some bamboo products are now constructed with different adhesives, so they qualify for this credit. Strand-woven products are not constructed with urea-formaldehyde and all qualify.



See more on this topic: Bamboo Flooring


 

Dan Harrington is a senior product specialist with Galleher Hardwood Co. in Santa Fe Springs, Calif., and a frequent NWFA instructor. He can be reached at dharrington@galleher.com.

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Hellena Chrones Sunday, 10 August 2014
Dan, I read your post. Do you have any information specifically about VOC formaldehyde emissions for Morningstar Qing Viper Strand Bamboo from lumber liquidators?
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I have stranded bamboo flooring and it isn't laying smooth. It seems to be rising a little at the seams. I'm sure seam is not the correct wording but where the floor is put together. It is like this over the whole floor. It is nailed down. It seems rippled all the way across the floor. Is this normal?
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I have exact same problem
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You say it is nailed down. That might well be the problem as bamboo flooring is typically left floating so it is free to expand and contract.
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i would bet that you have post cure issue for the strand that is caused by low quality flooring
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If your stranded bamboo is a click floor I don't think it should be nailed down. If the product expands and contracts similar to hardwoods the entire floor becomes a solid unit that needs to expand and contract as a unit. This means the floor needs to float so it is free to expand as it needs to. My hunch is that by nailing the boards down each board is now pushing against each other and the weakest place for the pressure to relieve itself is by pushing against each other and up at the seams. I am not a pro flooring installer but I am a very experienced woodworker and I am currently installing one of these floors. I think LL is giving bad advice by telling people to glue or nail down these floors because of this expansion issue. Regular click floors are engineered meaning they expand less because of the lamination layer. But a wood floor expands a lot - which the tongue and groove joints allow for. This product is really a new class because it's the first interlocking solid product I am aware of and the entire floor is going to expand as if it was one giant board.
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Mark
You are an anomaly here on this board, you are someone that truly understands wood/bamboo flooring when it pertains to movement and how it is installed, thank you. Unfortunately we don't know if this is a tongue and groove floor, or a floating floor, so it is hard to answer Dara's question. Based on the information it sounds like cupping, but a picture can normally tell the story. Thanks
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Stranded bamboo flooring comes in a wide range of construction and styles. Solid (grain running in one direction), Engineered (cross-ply construction), Traditional Tongue & Groove, Click locking Tongue & Groove. It helps to know what you are working with before formulating an opinion. Traditional tongue and groove strand bamboo has been in the U.S. marketplace for approximately 9 years. It has usually been mechanically fastened "nailed-down" for all those years. 18 -20 ga. cleats are recommended. If the floor has been fastened, what you are describing sounds like the usual cupping/crowning that occurs when solid products (wood included) have a moisture imbalance between the face and the backing. Most professionals will let you know this is a jobsite related environmental issue.
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I don't install any stranded bamboo unless it is acclimated for a minimum of 14 days. We always open both ends of the boxes. And open both plastic layers. I've been doing it this way for a few years and have not had a single issue.
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The vast majority of strand woven is inadequately dried prior to milling. It often suffers from dry cupping. Just measure the face. With all that resin, I can't see how there is any predictability to the acclimation. Good luck finding a meter company that will give you a true answer on reading the stuff. It's just another stupid chinese concoction designed for massive profits.
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We often attack that which we do not understand. I am sorry, but your blanket statement is incorrect. As someone who deals with products from all over the world, there is good and bad everywhere. (Including the good ol' U.S. of A.) The strand process was developed in China about 10 years ago. It is prominent all over the country in multiple brands and product lines. Don't always look for the cheapest, including your moisture meter. I hope you don't own a gun, because it still uses that "stupid Chinese concoction" gun powder.
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Danny Harrington Friday, 11 March 2016
Massive profits? Not at all. Most of the bamboo flooring mills have gone out of business, in large part because big U.S. Buyers ground them so hard on price that they responded by engineering out costs. Costs such as proper drying, quality resin, slow curing of the adhesive, quality raw material, etc. We are largely to blame, although the Chinese are also to blame for cutting corners without truly explaining (or understanding, in some cases) the consequences of lowering the costs like this.