Australian made Plywood is available in various lengths, widths and thicknesses. Standard sheet sizes are 1800mm, 2400mm and 2700mm in length and width is generally 1200mm. The most common sheet size carried by suppliers is 2400mm by 1200mm. Others upon request.
Imported plywood into Australia is generally imperial sizing and only available in a 2440mm length by 1220mm width.
Plywood thicknesses range from 3, 4, 6, 7, 9, 12, 15, 17, 18, 19, 20, 21, 25mm. Thicknesses vary between different manufacturers and products.
When specifying Australian made plywood the following information should be supplied:
- Type of Plywood including Australian Standard
- Stress Grade / Structural Rating (where required)
- Veneer Grade
- Glue Bond
- Treated or Untreated
For example, to specify Plywood Flooring
- 20 sheets
- 2400 x 1200 x 17mm
- F11 Tongue & Groove Structural Plywood, AS2269
- CD Grade
- EWPAA Certified
There are four types of glue bond for plywood manufacture described in decreasing order of durability.
Type A – produced from a phenol formaldehyde resin which, sets permanently under controlled heat and pressure. It gives a permanent bond that will not deteriorate in heat or cold or under wet conditions. It is used for marine plywood, structural plywood and exterior plywood which has long term exposure to wet or damp conditions.
Type B – produced from melamine fortified urea formaldehyde resin (MUF) which sets under controlled heat and pressure. Type B is suitable for plywood involved in up to two years full exposure to the weather such as in formwork plywood or exterior doorskins.
Type C & Type D – produced from urea formaldehyde resin (UF) which sets under controlled heat and pressure. These are interior bonds which are not recommended for any purpose where exterior conditions are involved. Even for interior purposes, C & D should not be recommended for structural applications. For areas around sinks, vanities and laundry tubs, Type A bonded plywood should be used.
There are four main veneer qualities specified for plywood and these are:
A high quality appearance grade veneer suitable for clear finishing.
An appearance grade suitable for high quality paint finishing.
A non-appearance grade with a solid surface. All imperfections such as knot holes or splits are filled.
A non-appearance grade with permitted open imperfections. Limited number of knots and knot holes up to 75mm wide are permitted.
Plywood stress grade range from Non-Structural, F8, F11, F14, F17, F22 & F27.
The higher the stress grade, the thinner the plywood requirement will be to perform the same structural function.
There are several methods of treating plywood
- impregnation of veneers, prior to manufacture;
- pressure treating of the manufactured plywood;
- preservation treating surfaces after manufacture;
A range of preservative treatments are available including
- copper chrome arsenate (CCA)
- light organic solvent preservatives (LOSP)
- Ruply and Ammoniacal Copper Quaternary (ACQ)
Pressure treatments such as CCA & LOSP are envelope treatments, that is, the plywood has been treated after manufacture. The outside of the plywood is treated and the inside of the plywood is untreated. If cut the plywood needs to be resealed.
Veneer treatments treat the individual veneer prior to laying up of the plywood and no further treatment should be required if cut.
Types of Plywood