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. 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.

HARDNESS CHART
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The numbers in the chart reflect the dimensional change coefficient for the various species, measured as tangential shrink-age 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, then 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 board's 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.

STABILITY CHART
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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).

How to use this chart: Costs for any species may vary according to current availability, location and other market factors. This chart is intended only to provide a comparison scale. Each species has been assigned a multiplier to be applied to the cost of plainsawn select red oak, chosen as the benchmark because of its widespread use in the flooring industry. Brazilian cherry, for example, has been assigned a cost multiplier of 1.30. If you know the cost of plainsawn select red oak, multiply by 1.3,and you have some idea what Brazilian cherry might cost.Please keep in mind, however, that these figures are only estimates; actual costs can vary greatly by locale, time of year and flooring style.

RELATIVE COST CHART
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