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 wall to half its diameter in wood. It is one of the best measurements 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. If you’re accustomed to working with Red Oak and decide to tackle a job with Brazilian Cherry, you can expect it to be much harder to cut and nail.
|Brazilian Cherry (jatoba)||2820|
|Sydney Blue Gum||2023|
|Red Oak (Northern)||1290|
|Antique Heart Pine||1225|
|American Black Walnut||1010|
|Southern Yellow Pine (Longleaf)||870|
|Southern Yellow Pine (Loblolly & Shortleaf)||690|
.Source: Hardness ratings for most species taken from Wood Handbook: Wood as an Engineering Material (Agriculture Handbook 72, Forest Product 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 percentage of tangential shrinkage from green to oven-dry moisture content)
The numbers in the chart reflect the dimensional change coefficient for the various species, measured as tangential shrinkage or swelling within normal moisture content limits of 6 – 14 percent. Tangential change values will normally reflect changes in plainsawn wood. Quartersawn wood will usually be more dimensionally stable than plainsawn.
The dimensional change coefficient can be used to calculate expected shrinkage or swelling. Simply multiply the change in moisture content by the change coefficient, than multiply by the width of the board.
Example: A mesquite (change coefficient – .00129) board 5 inches wide experiences a moisture content change from 6 to 9 percent – a change of 3 percentage points.
(Calculation: 3 x .00129 = .00387 x 5 = .019 inches).
In actual practice, however, change would be diminished in a complete floor, as the boards’ proximity to each other tends to restrain movement. The chart is best used for comparison.
* Although some tropical woods such as Australian Cypress, Brazilian Cherry, Merbau and Wenge appear in this chart to 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.
|Northern Red Oak||8.6|
|Brazilian Cherry (jatoba)||8.5|
|Brazilian Walnut (Ipe)||8.0|
|American Black Walnut||7.8|
|Southern Yellow Pine||7.5|
.Source: stability ratings taken from Wood Handbook: Wood as an Engineering Material (Agriculture Handbook 72, Forest Products Laboratory, Forest Service, U.S. Department of Agriculture; revised 1987).