The species of wood used to manufacture the plywood panel’s face and back are classified into five groups based on their bending strength and stiffness: group 1 being the strongest and group 5 the weakest.
The species are grouped on the basis of their mechanical properties for bending stiffness and bending strength. These are the most important properties for many plywood uses including concrete formwork. (Selecting the right panel type for concrete formwork).
Species are classified in accordance with the ASTM-D2555-06-Standard-Practice-for-Establishing-Clear-Wood-Strength-Values (see Appendix A in US standard PS 1-09). The species groupings are valid only for those grown in the region referenced in this standard.
|Group 1||Group 2||Group 3||Group 4||Group 5|
|North American Species (applicable to trees grown in North America)|
Douglas- fir a
Meranti, Red b,d
a: Douglas-fir from trees grown in the states of Washington, Oregon, California, Idaho, Montana, Wyoming and the Canadian provinces of Alberta and British Columbia shall be classed as Group 1. Douglas fir from trees grown in the states of Nevada, Utah, Colorado, Arizona and New Mexico shall be classed as Group 2.
b: Each of these names represents a trade group of woods consisting of a number of closely related species.
c: Species from the genus Dipterocarpus marketed collectively: Apitong if originating in the Philippines, Keruing if originating in Malaysia or Indonesia.
d: Red Meranti shall be limited to species having a specific gravity of 0.41 or more based on green volume and oven dry weight.