The Janka hardness test measures how durable a sample of wood or bamboo is against denting and common wear and tear. The test uses an 11.28mm steel ball which is forced into a test piece of wood. It is the force required to embed the steel ball that is measured. The results indicate whether a piece of wood is acceptable to be used in a particular building application, but the test is commonly used to determine if a material is suitable for flooring.
The hardness of wood or bamboo varies depending on the direction of the grain. Tests that are performed on the surface of a plank, perpendicular to the grain, are called “side hardness” tests, and tests performed on the cut surface of a stump are called “end hardness” tests.
What Exactly do the Results Mean?
As we mentioned, the Janka hardness test measures the resistance of a sample of wood or bamboo to denting and wear and tear. This is important because you want to know your floors are going to be able to stand up to major wear and tear, and even sometimes abuse from pets and kids. The higher the number, the more force it takes to embed that little steel ball into the wood or bamboo sample. Flooring with a high Janka rating, say between 2,000 and 5,000, means it is very durable.
Douglas Fir has a Janka hardness rating of 660 which tells us that Douglas Fir is an incredibly soft wood and probably not suitable for flooring. On the other end of the scale, Australian Buloke has a rating of 5060 – very strong indeed, but it is so dense that it has a difficult time holding finish (the finish can’t permeate the surface), so it also is not suitable for all types of flooring. Brazilian cherry has a hardness rating in the middle of 2350 and Brazilian walnut has an even higher rating of 3800. These woods are very hard and would make excellent flooring options. They are however, incredibly expensive.
Another Durable Flooring Choice
You might be thinking now that bamboo can’t possibly have a high Janka rating because it is a grass and not a hardwood, but that’s simply not the case. Depending on how the bamboo is manufactured, it can have as low a rating as 900 (making it close to Douglas Fir) or as high a rating upwards of 4000, making it incredibly durable.
Traditional bamboo flooring typically has the hardness rating in the 1300 range, which is the same rating as oak. That’s pretty durable. Strand-woven bamboo has an even higher rating of 2000-3200 which, you may recall, is the same rating as Brazilian cherry and teak. The biggest difference between bamboo and Brazilian cherry or teak is that bamboo floors cost far less and bamboo renews much quicker than hardwoods which makes it the more eco-friendly option.
So, if you’re looking for a flooring choice with a high Janka rating that’s beautiful, affordable and environmentally-friendly, consider bamboo for your home remodel.