EN 324-2: 1993

Wood-based Panels – Determination of squareness and edge straightness

Part 2 specifies methods for measuring the squareness and edge straightness of wood-based panels.  It applies to whole flat boards.


Use a mechanical square having two arms each 1000mm (±1mm) length fixed at right angles to one another.  Place one side of the square against one side of the panel.  At the end of one arm measure the distance between the side of the arm and the edge of the panel.  Follow the same procedure for each of the other corners.

The result is the largest measured value of the deviation of the side of the square and the edge of the panel expressed in mm over 1m panel edge –length to the nearest 0.5mm/m.

Straightness of panel edge

Use a straight edge equal in length to the length of the panel or a wire of constant cross-section and flexible enough to be stretched taut.  Place the straight edge against the panel edge or position the wire at the corners of the panel and stretch it. Measure the largest deviation between the straight edge or the wire and the panel edge.  Read the result to the nearest 0.5mm.  The result is expressed in mm/m for both the width and the length of the panel and is the largest value of the measured deviation divided by the appropriate length or width.

For comparison: APA method for measuring the squareness and straightness as per US PS 1-09 Structural Plywood and US PS 2-10 Performance Rated OSB


Panels should be square within 1.3mm per lineal metre of the longest edge (1/64” per lineal foot) measured along the diagonals.  This equates to a maximum difference between the lengths of the two diagonals of 3.172mm for an 8’ x 4’ panel.


The maximum distance from the panel edge to a straight line drawn tight between two adjacent corners shall be 1.6mm (1/16”).