Understanding Plywood Grading Systems: A Buyer's Reference

Why Plywood Grades Matter

Plywood grading communicates product quality in a standardized way. A grade specification tells you about the surface quality (face and back), bonding strength (glue performance), and emission level (formaldehyde). Understanding grading systems helps you specify the right product for your application without over-specifying (paying too much) or under-specifying (getting inadequate quality).

Face and Back Veneer Grades

Plywood panels have two surfaces: the face (the better side, intended to be visible) and the back (the reverse side). Each is graded separately.

International Grade Scale

Grade	Appearance	Allowed Defects	Typical Use
A	Premium, smooth	No open defects; minor patches allowed	Furniture face, architectural
B	Good, minor defects	Small knots (≤6mm), minor splits repaired	Visible surfaces, cabinetry backs
BB	Acceptable	Knots, patches, minor discoloration	Industrial, concealed construction
C	Utility	Knots to 25mm, open splits, discoloration	Sheathing, subflooring
CC	Economy	Larger knots, overlaps, open defects	Packaging, pallets, temporary use
D	Reject for face use	Any defects; used only as inner plies	Core veneers only

Reading a Grade Specification

Grades are written as Face/Back. Examples:

• A/B: Premium face, good back — furniture, cabinetry
• B/C: Good face, utility back — general construction, visible one side
• BB/CC: Industrial grade — non-visible construction, packaging
• C/D: Utility — sheathing, concrete formwork (covered by film/overlay)

Bonding Classification

Bonding class indicates how the plywood performs under moisture and temperature stress:

Standard	Class	Glue Type	Environment
EN 314	Class 1	MR (Urea)	Dry interior only
EN 314	Class 2	MR+ (Melamine)	Humid, protected exterior
EN 314	Class 3	WBP (Phenolic)	Exterior, marine
US PS 1	Interior	Type II	Interior
US PS 1	Exterior	Type I	Fully exterior

For construction and export plywood, WBP (Class 3) bonding is the standard. It ensures the panel can withstand boiling water testing without delamination — critical for formwork and outdoor applications.

Formaldehyde Emission Grades

Standard	Grade	Limit
EN 13986 (EU)	E1	≤ 0.124 mg/m³
EN 13986 (EU)	E0.5	≤ 0.062 mg/m³
CARB P2 (US)	Phase 2	≤ 0.05 ppm
JAS (Japan)	F☆☆☆☆	≤ 0.3 mg/L
JAS (Japan)	F☆☆☆	≤ 0.5 mg/L

For US-bound plywood, CARB P2 compliance is mandatory. For EU, E1 is the minimum; E0.5 is increasingly preferred.

How to Specify Plywood Correctly

A complete plywood specification should include:

1. Panel type: Film Faced / MDO / HDO / Commercial
2. Dimensions: Thickness × Width × Length (e.g., 18 × 1220 × 2440 mm)
3. Core species: Acacia / Eucalyptus / Styrax / Mixed
4. Face/Back grade: e.g., B/C
5. Bonding class: e.g., WBP (EN 314 Class 3)
6. Emission grade: e.g., CARB P2 / E1
7. Overlay: Film weight and type (e.g., 220g/m² brown film both sides)
8. Certifications: FSC, CE, etc.

Use our Plywood Selector to build specifications interactively, or browse pre-configured products in our Product Catalog.

Frequently Asked Questions

Does face grade affect structural strength?

No. Face veneer grade is purely cosmetic — it describes surface appearance defects. Structural strength comes from core construction, bonding quality, and panel thickness. A C/D grade panel can be just as strong as an A/B panel of the same construction.

What grade do I need for concrete formwork?

For film faced formwork plywood, the underlying veneer grade is typically B/C or C/D — the film overlay covers the face anyway. What matters more is bonding class (WBP required), film quality, and core density.

Why is the same "grade" different between suppliers?

Grading is somewhat subjective and varies between factories. One manufacturer's "B" grade may be another's "BB." This is why requesting samples and test reports is essential — never rely solely on grade designations when comparing suppliers.