Plywood is a widely used building material in Australia, well-known for its durability, strength, and aesthetic appearance. However, not all plywood sheets are created equal. Understanding the various grades of plywood is crucial for making informed choices in design and construction.
When considering plywood, think about the following:
- Appearance Requirements: Select higher plywood grades (such as A or B) for visible surfaces and lower grades (B or C) for non-visible surfaces and carcasses.
- Application: Determine whether the boards will be used for structural, non-structural, interior, or exterior purposes.
Below is a guide of plywood appearance quality grades according to AS/NZS 2269:
Plywood Grades Guide
|
Grade |
Description |
Applications |
|
A Grade* |
Smooth, defect-free surface; high aesthetic quality. |
Furniture, cabinetry, decorative panels. |
|
B Grade** |
Minor defects; visually acceptable for many applications. |
Cabinetry and visible applications. |
|
C Grade*** |
Noticeable defects; still structurally sound. |
Painted surfaces, general construction. |
|
D Grade**** |
More defects; used in non-visible applications. |
Sheathing, subflooring, general utility. |
For any 300 mm line drawn across the grain of the plywood board, the cumulative dimensions of gaps in edge joints, along with knots, splits, holes, patches, bark inclusions, resin pockets, gum veins, and areas of inactive decay, must not surpass the specified limits:
* Plywood Grade A (softwood - 75mm, hardwood - 45mm):
- Permitted imperfections: Grade A plywood is required to have a smooth, defect-free surface, with no visible knots, splits, or other blemishes (for example, filled holes - up to 6mm, knots - up to 4mm).
- Minimal Repair: Any fixes made must be of premium quality and nearly invisible, ensuring a flawless surface appearance.
** Plywood Grade B Defects (softwood - 75mm, hardwood - 45mm):
- Small Knots: Tight knots that are not bigger than a specific diameter (not exceeding 25 mm).
- Tight Splits: Minor surface splits that do not affect structural integrity.
- Blemishes: Small surface imperfections, such as discoloration or minor sanding marks are permitted with no limitations.
- Patching: Minor repairs may be present, provided they are well-executed and blend with the surface.
*** Plywood Grade C Defects (softwood - 120mm, hardwood - 75mm):
- Wormholes: Small holes from insect activity.
- Knots: Small to medium-sized knots that may be loose or tight.
- Knotholes: Open holes left by fallen knots. Filled holes - up to 50mm.
- Splits: Minor splits or checks in the wood surface.
- Blemishes: Surface imperfections such as surface irregularities or discoloration.
**** Plywood Grade D Defects(softwood - 120mm, hardwood - 75mm):
- Wormholes: More extensive insect damage.
- Large Knots: Bigger knots that may be loose or tight.
- Knotholes: Larger or more numerous holes from knots. Unfilled holes - up to 75mm.
- Cracks and Splits: More significant splits or checks throughout the board.
- Unfilled Defects: Open defects that are not repaired or filled.
- Bark Inclusion: Areas where spots of bark is present on the surface.
How to read the grade of plywood?
The standard Australian surface grade is indicated by a two-letter designation, where the first letter represents the quality of the face side veneer and the second letter represents the back side veneer. For example, a AB grade signifies that the plywood has a A grade face veneer and a B grade back veneer. The quality of the veneer is assessed in the completed panel.