What is the Janka Scale? (Janka Hardness Rating)

For those who can’t resist the look and feel of real wood, the Janka Scale can be a valuable tool. While composite and vinyl decking lead the industry in quality, comfort, and longevity, some homeowners still prefer the natural appeal of real wood when investing in a new deck.

The Janka Scale helps determine which type of wood is best suited for your project. It measures how hard a wood species is, which in turn helps indicate its durability and long-term performance. Depending on where you live in the United States, climate and weather conditions will also play a key role in your decision. Choosing a wood that is both strong and beautiful is a must. 

What Is the Janka Scale?

The Janka Hardness Scale assigns each wood species a numerical rating based on its hardness. The system is named after Gabriel Janka, an Austrian wood researcher who worked for the U.S. Department of Agriculture. In 1906, he developed a test to measure the force required to embed an 11.28-millimeter steel ball into a piece of wood to half its diameter. Though refined over the years, the method remains the same and is widely recognized today.

For interior flooring, a Janka rating of 1000 or higher is typically ideal. Decking, however, is exposed to much harsher outdoor conditions, so selecting a wood species with a rating above 1000 is generally recommended.

Common Wood Ratings

Ipe (Brazilian Hardwood): With a Janka rating of 3680, Ipe is extremely hard and durable, making it suitable for both indoor and outdoor use. Like all natural woods, it requires maintenance such as annual staining or sealing. Over time, it will naturally weather to a silver-gray color.

Cedar: Known for its character, natural resistance to decay, and pleasant aroma, cedar has a Janka rating of around 900.

Pressure-Treated Wood: A cost-effective option made from southern pine or Douglas fir, typically with Janka ratings in the 600s.

Choosing the Right Wood

If you’re committed to building your deck with real wood, the Janka Scale can help guide your choice. Remember that harder woods usually cost more than softer ones, and all wood will weather and deteriorate over time. With regular maintenance and the time and budget to support it, your hardwood deck can remain strong and beautiful for many years.

At Hickory Dickory Decks, we help homeowners across the U.S. choose the right materials for lasting performance and beauty in every climate.