DIY Projects

Plywood Terminology

Submitted by: Woody Wall on November 25, 2011


  • Back of plywood panel - The side of a panel that is of lower veneer quality on any panel whose outer plies (front and back) are of different veneer grades.
  • Back ply of a plywood panel - The outer veneer on the back side of a panel.
  • Borer holes - Voids made by wood-boring insects, such as grubs or worms.
  • Broken grain - A (leafing, shelling, grain separation) separation on veneer surface between annual rings.
  • Butt joint - A straight joint in which the interface is perpendicular to the panel face. An end butt joint is perpendicular to the grain.
  • Centers - Inner layers whose grain direction runs parallel to that of the outer plies. Some centers consist of parallel laminated plies.
  • Construction (panel construction) - Term referring to detailed manner in which veneers are assembled and/or thickness of veneer used, e.g. “4-ply/3 layer construction,” “2.5mm (1/10-inch) face and back,” etc.


  • Face of the plywood panel - The side of a panel that is higher veneer quality on any panel whose outer plies (front and back) are of different veneer grades; either side of a panel where the grading rules draw no distinction between outer plies.
  • Face ply of a panel - The outer veneer on the face of a panel.
  • Finger Joint - A term indicating the method by which panels or sections of panels have been joined to create longer lengths or widths by means of a well-bonded series of sloped scarf cuts resembling fingers.
  • Grade name - Term used to identify panels having special characteristics and/or requirements such as Marine, Decorative and Underlayment.
  • Heartwood - Nonactive core of a log generally distinguishable from the outer portion (sapwood) by its darker colour.
  • Knot - Natural characteristic of wood that occurs where a branch base is embedded in the trunk of a tree. Generally the size of a knot is distinguishable by (1) a difference in colour of limb wood and surrounding trunk wood: (2) an abrupt change in growth ring width between knot and bordering trunk wood; (3) a diameter of circular or oval shape described by points where checks on the face of a knot that extend radially from its center to its side experience an abrupt change in direction.
  • Knotholes - Voids produced by the dropping of knots from the wood in which they were originally embedded.
  • Delamination - A visible separation between plies that normally receive glue at their interface and are firmly contacted in the pressing operation. Wood characteristics, such as checking, leafing, splitting and broken grain, are not to be construed as delamination.
  • Shop-cutting panels - A panel which has been rejected as not conforming to a standard grade because of deficiencies, other than adhesive bond quality, which prevent it from meeting the requirements of this standard. Blistered panels are not considered as coming within the category of “shop-cutting panel.” Localized delamination occurs as a result of a deficiency. However, shop-cutting panels are suitable for cut-up use where cutting eliminates the deficiency in the portion of the panel salvaged.