What is the Janka Hardness Scale?

Whenever you talk about hardwood flooring people begin quoting figures from the Janka scale. Have you ever wondered what is the Janka scale and why is it so popular? If yes, this article is a must read.

Understanding the Janka Scale

When someone buys hardwood out of the many factors that he considers, one is the hardness of wood. The Janka scale or the Janka rating system measures the relative hardness of wood. In scientific terms this is the force in pounds required to embed a 0.444 inches (11.28 mm) steel ball into wood up to half its diameter. This leaves a 100 square mm indentation in the wood being tested. The Janka scale thus tells us how hard the wood is.

The hardness of the wood varies with the direction of the wood grain.

• If the wood surface of a plank is tested at right angles to the grain it is called the Side Hardness Test.
• If the cut surface of a wood stump is tested it is called The End Hardness Test.

If you were to test a hardwood floor for its hardness, you will find that your values may not exactly match the standard values. This is because Janka tests are performed on raw material wood stock and not on actual flooring material. The final values are an average of multiple test values.

The Janka Scale and Hardwood Flooring

• The hardness of wood has two important considerations. The harder the wood is the more it will withstand wear and tear. A higher Janka rating thus indicates greater durability and stability. Such woods are ideal for flooring and can put up with a lot of traffic.
• As the hardness of wood increases it becomes difficult to saw or nail. Woods with lower Janka scale readings fare better with the saw.

Some of the common wood species and their position on the Janka scale are:

• White Pine – 420
• African mahogany – 830
• North American Walnut – 1010
• Teak – 1155
• Red Oak – 1290
• Ash – 1320
• Maple – 1450
• Mesquite – 2345
• Ebony – 3220

Which hardwood is the best for flooring?

Hardwood is a natural material that is not produced under stringent factory conditions. Wood grows naturally and is affected by varying temperature and humidity. Soil, wind and microbial flora also affect the wood. Nature’s elements design the wood and give it a special character. Thus, the wood of each tree is unique in its looks, hardness and design. Hardness is just one of the factors that you need to consider when buying hardwood flooring. Find out the Janka reading of the different types of wood. If you are looking for hardwood flooring for a room that puts up with a lot of abuse choose a wood with higher Janka rating. Other factors like the color of the wood, its price and how well it blends with your interiors are also important.

The Janka scale readings do not necessarily correlate with price. Woods that are higher on the Janka rating may not be more expensive. Usual run off the mill, hardwood flooring is cheaper whereas flooring made of rare, exotic woods is expensive. After all you need a beautiful floor and not a bomb proof bunker. Woods are priced according to availability, grade of flooring, texture, finish and uniqueness. The laws of economics and nature also play a major role in determining wood prices. Thus slow growing woods, woods whose trade is restricted by law and woods imported from distant sources are often rare and expensive.

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