Hardness Charts

Relative Hardness of Selected Wood Flooring Species

(Ranked by Janka hardness rating)

The Janka (or side) hardness test measures the force required to embed a .444-inch steel ball to half its diameter in wood. It is one of the best measures of the ability of a wood species to withstand denting and wear. By the same token, it is also a good indicator of how hard or easy a species is to saw or nail. Northern red oak, for example, has a Janka hardness rating of 1290. Brazilian cherry, with a rating of 2350, is nearly twice as hard.

Source: Hardness ratings for most species taken from Wood Handbook: Wood as an Engineering Material (Agriculture Handbook 72, Forest Products Laboratory, Forest Service, U.S. Department of Agriculture; revised 1987), except for Australian cypress, wenge, African padauk, merbau and Santos mahogany, which were provided by International Hardwood Flooring; heart pine by Mountain Lumber, and mesquite by Mesquite Products of Texas.

Douglas fir rating is an average of ratings for Coast, Interior West and Interior North species.

Relative Stability of Selected Wood Flooring Species

(Ranked by dimensional change coefficient)

This chart is best used for comparison. The dimensional change coefficient can be used to calculate expected shrinkage or swelling. In actual practice, however, change would be diminished in a complete floor, as the boards' proximity to each other tends to restrain movement.

*Although some tropical woods such as Australian cypress, Brazilian cherry, merbau and wenge appear in this chart or have excellent moisture stability compared to domestic oak, actual installations of many of these woods have demonstrated significant movement in use. To avoid problems later, extra care should be taken to inform potential users of these tendencies prior to purchase.

Source: Stability ratings taken from Wood Handbook: Wood as an Engineering Material (Agriculture Handbook 72, Forest Products Laboratory, Forest Service, US Department of Agriculture; revised 1987)