Australian Plywood Grades Explained: A, B, C, D, and O

When it comes to selecting the right plywood for your project, understanding the different veneer grades is essential. Each grade—A, B, C, D, and O—serves specific purposes and meets distinct Australian Standards, ensuring optimal performance and suitability for various applications. Here's everything you need to know about these plywood grades.

A Grade: The Pinnacle of Appearance

A-grade plywood represents the highest quality standard, offering a flawless and smooth surface designed for decorative applications where aesthetics matter most. It’s an excellent choice for visible surfaces like furniture and cabinetry, ensuring a premium finish that enhances any project. Features like tightly controlled imperfections and minimal color variation make A-grade plywood the benchmark for top-tier applications.

Non-Permitted Imperfections:

  • Bark, gum, and resin pockets
  • Unfilled holes, splits, and open edge joints
  • Loose, encased, or unsound knots
  • Disfiguring discoloration or stains
  • Glue bleed-through
  • Resin streaks and gum blotches

Permitted Imperfections:

  • Filled holes not exceeding 6 mm measured across the grain, with a total area not exceeding 30 mm² and a maximum of four per sheet
  • Sound knots (up to 4 mm) with no more than four per sheet
  • Sound pin knots (up to 2 mm) provided the sheet’s appearance is unaffected
  • Filled splits not exceeding 3 mm measured across the grain and 450 mm² per face, with no more than two per face
  • Filled edge joints (up to 3 mm wide and 450 mm² per face)
  • Slight natural discoloration and stain
  • Slight roughness associated with permitted imperfections
  • Sloping grain (up to 1 in 7 over one quarter of the sheet area)
  • Veneer pieces of unequal width provided no piece is less than 150 mm wide
  • Inserts (shims) neatly made with parallel grain direction

Applications: Ideal for furniture, cabinetry, and other high-visibility uses where a premium appearance is required.

Example: Austral Araucaria Hoop Pine A/C Exterior Plywood

B Grade: Reliable and Durable

B-grade plywood balances aesthetics and durability, making it suitable for interior projects that require a smooth finish but can tolerate minor imperfections. It’s a versatile option for paneling, shelving, and joinery that will be painted or laminated. B-grade plywood retains much of the quality of A-grade but allows for slightly more noticeable imperfections, providing excellent value for mid-range projects.

Non-Permitted Imperfections:

  • Bark, gum, and resin pockets
  • Unfilled holes, splits, and open edge joints
  • Loose, encased, or unsound knots
  • Resin streaks and gum blotches

Permitted Imperfections:

  • Filled holes not exceeding 20 mm across the grain, with a total area of 600 mm² per face
  • Sound knots up to 40 mm across the grain (no more than four per sheet for knots larger than 25 mm)
  • Filled splits and tight gum veins not exceeding 3 mm wide, tapering to a point, with a maximum area of 750 mm²
  • Filled edge joints up to 3 mm wide with a total area of 750 mm²
  • Discoloration and stains without limitation
  • Slight glue bleed-through
  • Sloping grain up to 1 in 7 over one quarter of the sheet area
  • Slight roughness associated with local imperfections

Applications: Used in paneling, shelving, and joinery projects where the surface finish will be covered or painted.

Example: B/BB Birch Plywood , Lightweight Interior Plywood BB/CC

C Grade: Functional and Versatile

C-grade plywood delivers a practical and cost-effective solution for structural applications. Minor defects, such as filled splits and moderate discoloration, are allowed but must not compromise the sheet’s structural integrity. It is often chosen for projects where function takes precedence over appearance, such as subflooring, roof decking, or temporary structures.

Non-Permitted Imperfections:

  • Open defects, including holes and splits
  • Loose knots

Permitted Imperfections:

  • Filled holes up to 50 mm across
  • Filled splits up to 5 mm wide, tapering to a point, with a total area not exceeding 1000 mm² per face
  • Discoloration and stains
  • Moderate surface roughness
  • Filled edge joints up to 3 mm wide, with a total area of 750 mm² per face

Applications: Perfect for subflooring, roof decking, and concrete formwork where structural integrity takes precedence over appearance.

Example: B/C Structural Plywood , Hardwood Exterior BB/CC Plywood

D Grade: Economical and Practical

D-grade plywood offers an economical solution for structural applications where appearance is not a concern. Its open imperfections, such as unfilled holes and splits, make it a cost-effective choice for basic construction tasks, packaging, and crates. Despite its allowance for imperfections, D-grade plywood remains structurally sound and reliable for projects requiring utility over aesthetics.

Non-Permitted Imperfections:

  • Structural defects that compromise integrity

Permitted Imperfections:

  • Open knots and holes (size not restricted)
  • Splits that may remain unfilled
  • Discoloration and roughness

Applications: Commonly used in packaging, crates, and areas where appearance is irrelevant.

O Grade: Optimised for Marine Use

O-grade plywood is specially engineered to meet the rigorous demands of marine environments. Its superior water-resistant properties and high durability make it the go-to choice for moisture-prone applications such as boat building and marine construction. This grade’s robust design ensures reliability and longevity even under constant exposure to water.

Non-Permitted Imperfections:

  • Loose, encased, or unsound knots
  • Unfilled holes, splits, or open edge joints

Permitted Imperfections:

  • Small filled holes up to 6 mm measured across the grain with a total area of 30 mm²
  • Sound pin knots up to 2 mm across the grain
  • Slight natural discoloration and stain
  • Filled splits up to 3 mm wide, tapering to a point, with a total area not exceeding 450 mm² per face
  • Filled edge joints up to 3 mm wide and 450 mm² per face
  • Inserts (shims) neatly made with parallel grain direction

Applications: Ideal for marine construction, boat building, and other high-moisture environments.

Example: Imported Marine Plywood BS 1088

Choosing the Right Grade for Your Project

When selecting plywood, consider the following:

  • Appearance: For visible surfaces, choose A or B grade.
  • Functionality: For structural purposes, C and D grades offer practicality and cost-effectiveness.
  • Environment: For wet or marine environments, O-grade is the optimal choice.

With a clear understanding of the unique properties and applications of A, B, C, D, and O grade plywood, you can confidently select the material that best suits your needs.

At Bord Products, we are committed to providing a wide range of plywood options that meet Australian Standards and cater to every project requirement. Whether you’re working on a residential renovation, a commercial build, or a marine project, we have the perfect plywood solution for you.

Explore our full range of products at Bord Products or contact our expert team today—we’re here to help bring your vision to life.