Direction of Face Grain

For greatest strength and stiffness, plywood should be installed with the face of grain perpendicular to the supports. Section prop­erties parallel to the face grain of the plywood are based on panel construction which gives minimum values in this direction. Prop­erties perpendicular to the face grain are based on a usually differ­
ent panel construction, which gives minimum values in that direc­tion (Figure 1.6).

For design purposes, calculations must take into account in which direction the stresses will be imposed in the panels. If stresses can be expected in both directions, then both the parallel and the perpendicular direction should be checked.