Structural plywood is a series of timber veneers glued and pressed at right angles to each other to form a rigid board.
Radiata Pine veneers are normally used in Structural plywood.
A waterproof type “A” Bond glue is used in Structural plywood. The glue is usually identified by its red/brown/black colour. The glue bond is tested by 72 hour boil test.
The veneers are coated with glue then hot pressed under extreme pressure to set the glue and Structural plywood is the result of this process.
Structural plywood is normally pressed in uneven layers of veneers. Different thickness veneers are utilised to achieve varying plywood thicknesses.
Structural plywood is available in 2400 x 1200mm
Some products are available in 2700 x 1200mm
Preservative LOSP Treatment
Light Organic Solvent-borne Preservatives (LOSPs) are preservatives that contain combinations of fungicides and insecticides for timbers used in internal and external situations. All of these preservative components are incorporated in a solvent carrier such as white spirit.
LOSP treated timber may retain some of the solvent used in the treatment process for a period of time after treatment. The following precautions should be taken to minimise any potential health effects to users:
LOSP treated timber should be stored in a well ventilated, under cover area with any protective wrapping removed.
Where possible packs should be opened a day or two before use to allow any residual solvent vapours in the inner boards to evaporate.
Preservative CCA Treatment
Structural plywood is generally impregnated to H3.2 hazard class with CCA (Copper Chrome Arsenic) treatment to AS/NZS1604.3:2002. H3.2 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 at a 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.