One of the most important things to consider when choosing which type of wood flooring is best for your home is the durability of the wood. This is especially true when you have pets and children. While the hardness of the wood isn’t the only factor in your floor’s durability, it is definitely part of the equation. Thankfully it is also an easy thing to determine, thanks to the Janka test and the Janka hardness scale.
Gabriel Janka was an Austrian wood researcher who worked for the Forest Products Lab of the U.S. Department of Agriculture (USDA). As part of his job, he was asked to scientifically measure the hardness of U.S. hardwoods. The wood rating scale he developed in 1906 was standardized in 1927 by the American Society for Testing and Materials (ASTM) and is now used around the world.
How does the Janka test determine how hard a wood is?
The Janka Hardness Scale determines the hardness of one particular domestic or exotic wood species over another. The Janka test uses a 2″ x 2″ x 6″ piece of wood and a 0.444″ steel ball. The test figures out how many pounds per square inch of force is needed to push the steel ball half-way into the wood plank. The test is carried out on wood from the trunk of the tree (known as the heartwood) and the standard sample has 12% moisture content and is clear of knots.
The Janka test isn’t perfect
The grain of the wood can cause the results to vary slightly. It’s normal if the grain is flat, so these test results are presented on the Janka scale. Vertical wood grains are tested too, but those results are not usually shown on the scale.
The way the Janka scale is stated is different from country to country. For instance, in the United States, the Janka ranting is supplied in pounds-force, whereas in Sweden it is stated in kilograms force, and in Australia, it is stated in Newtons.
Hardwood and Softwood
The Janka Hardness Scale starts at zero. On this end of the scale, we find the soft woods that are less dense, and easier to scratch and dent. Balsa wood, a wood commonly used in crafts, ranks at 100 on the scale, making it the softest wood on many scales.[1]
Woods with a higher rating are harder than woods with a lower rating.
The hardest floor may not be the best floor
On the high end of the scale are the harder woods. The scale’s highest rating is 4000. The harder a wood is, the more difficult it becomes to run through a mill, and later to cut with a saw, hammer or screw.
The hardness serves as an indicator of how well the floor will withstand wear and tear day to day, rather than how strong the wood is, or how soft a floor is in terms of comfort. A rating of 1000 or higher is the standard for flooring options.
Red Oak has a rating of 1,290 PSI. Because it is one of the most readily available hardwoods, Red Oak is the median standard. It’s the benchmark against which all other wood species are compared on the Janka Scale. Strong and resilient, Red Oak makes a great hardwood floor.
Some examples of other woods on the Janka scale in PSI:
Hickory 1820
Hard Maple 1450
White Oak 1360
Ash 1320
Beech 1300
Red Oak 1290
Birch 1260
Plantation Teak 1050
Black Walnut 1010
Cherry 950
Soft Maple 950
Using the Janka scale to help choose your wood floor
While the Janka hardness test and rating scale are an excellent way to determine what wood species might work for the floors in your home, there is more to consider. No matter which wood you choose, your hardwood floor will need to be taken care of, in order to withstand the wear of time. If it isn’t taken care of, it doesn’t matter how hard or soft it is. Choose a hardwood floor based on its look and price before anything else.
If you need help deciding which wood is the best choice for your needs, contact the experts at Dave’s Floor Sanding & Installation.
[1] Although it’s the softest wood around, Balsa wood is technically a hardwood. The terms, hardwood and softwood are somewhat misleading. They actually and have nothing to do with the hardness of the wood. Instead, these terms are related to botany. Angiosperms are referred to as hardwoods, while gymnosperms (aka conifers) are softwoods. While some softwoods can be somewhat hard, in general, most hardwoods are harder than softwoods, and certainly the very hardest woods in the world are all hardwoods.