What is plywood?
Plywood is made from timber, which has been cut into sheets and pressed together using adhesive. (Did you know, the Egyptians were the first to make plywood?)
Plywood is made from veneers that are peeled from a log that has been steamed in a log pond.
The veneer ends up as a long ribbon of veneer that goes from the outside of the long right down the core, and quality is then graded at that point.
The veneers are then laid up and applied with resin at a 90-degree angle to the next veneer, so that the grains of the wood are in different directions.
They are then pressed into plywood, which is then trimmed and packed.
Plywood has range of properties that make it and ideal building material, including:
- A high strength to weight ratio
- Great flexibility
- Excellent thermal and noise insulator
Types of resin used for bonding the veneers
There are 3 main types of resin types (BSEN314/2 Classes 1 2 and 3).
Class 1 – Urea Formaldehyde – This is purely internal only and in low humidity areas.
Class 2 – Melamine Urea Formaldehyde – Humid conditions , damp internal uses and must be protected from direct wetting both internally and externally.
Class 3 – Phenol Formaldehyde - Exterior conditions *
What is the most important factor when it comes to choosing plywood?
Choosing the right plywood class
“It’s important to choose the right plywood depending on what you plan to use the plywood for. This will ensure that the plywood you choose works for it’s given job”, say Pat Collins, Timber Products Manager.
“You should consider how and where the plywood will be used, particularly whether it will be used internally or externally, and whether or not it will be exposed to any moisture.
“And if it’s structural (point loading) and/or having a finish applied to it.
“You will either need a class 1, 2 or 3 plywood.”
