Product Catalogue

Structural Manual

Veneer and Knots

The veneer peeled from logs may contain characteristics such as knots or splits.  The size of knots and splits are controlled by grading into categories of different qualities.  Knotty plywood can be used for many applications.  Knots can be removed and replaced with wood or synthetic patches to enhance appearance.  To obtain veneer with no knots, more expensive pruned logs are peeled.


The glues used to bond the veneers together are synthetic phenolic resins, which are set and cured by heat and pressure under controlled conditions to form a strong and durable bond.  Plywood can be used for applications requiring strength, stiffness and durability, and may be specified for its aesthetic qualities or because of its origins within a renewable resource.  The choice of products depends on the application.

Preservative Treatment

If treated, structural plywood is generally impregnated to H3 Hazard class with CCA (Copper Chrome Arsenic) treatment to AS/NZS 1604.3:2002.  H3 CCA treated plywood in accordance with AS/NZS 1604.3:2002 is comparable to H3.2 and H3 LOSP is comparable to H3.1.

H3 hazard class is described as: “outside, above ground, subject to periodic, moderate wetting and leaching.”  Refer to the Standard for more detail.

CCA waterborne preservative is used for structural plywood.  It has a green colour, and is dried following treatment so that the sheets may return to the correct dimensions and are moisture content suited to use in building.  The fillets used to separate sheets in drying may leave marks on the sheet surface.  These fade after a time, and are easily covered with paint but may be visible under stain.

The process of treating with CCA and subsequent drying is likely to increase the face checking of the panel.  Refer CHH Woodproducts Technical Note 01/06/62 “CCA  plywood – surface quality.”

Structural Product Information

Face Grade B

Face Grade C

Face Grade DD

Ply BD Ply CD Ply DD
Visual Grade of Face
Structural appearance grade with minor repairs.  Suitable for high quality paint finish.
Visual Grade of Face
Solid sanded surface with filled holes and splits, with small-intergrown knots.  Suitable for a basic paint finish.
Visual Grade of Face
Usually sanded surface with unfilled holes up to 75mm across the face veneer.  Splits and knots also allowable.
Some suggested uses
  • Furniture
  • Joinery
  • Interior lining
  • Sheathing
  • Signs
Engineering components where a higher finish is required
Some suggested uses
  • Concrete formwork
  • Structural gussets
  • Roof decking under tiled systems
  • Bins, boxes, crates
  • Sub sheathing
  • Hoardings
  • Stressed skin panels
Some suggested uses
  • Structural applications
  • Box and C beams
  • Portal frame webs
  • Gussets
  • Roofing under tile
  • Crates
  • Strength critical pallets

Ply Flooring

Ply Roofing

  Has a higher crossband under the face Unsanded to allow grip for workers on sloping roofs
  Some suggested uses
  • T&G Flooring
  • Roof decking under rubber membranes
  • Most other roofing
  • H3 CCA water based treated substrate for flexible membranes
Some suggested uses
  • T&G underlay for asphaltic tile
  • Roof systems where a smooth substrate is not required