EN 636 Plywood - Properties

The European standard "EN 636 Plywood - Specification" specifies the requirements for plywood for both general-purpose use (non-structural application) and structural application in dry, damp, or outdoor conditions, as defined in "EN 313-2 Plywood - Classification and terminology - Part 2: Terminology." This standard also provides a classification system based on bending properties.

This standard is referenced in EN 13986 for construction applications. This standard is applicable to all plywoods, including veneered and overlaid plywood, as appropriate, but does not cover the materials or processes used for overlaid or overlaid plywood. It also does not cover any materials or processes used to increase biological durability.

For the purposes of this standard, the following terms and definitions apply:

• Plywood for dry use refers to plywood intended for use in conditions characterized by a moisture content of 20°C and a relative humidity exceeding 65% for only a few weeks per year. These conditions correspond to service class 1 according to EN 1995-1-1. Boards of this type are suitable for use in service class 1 according to EN 335-3.
• Plywood for use in humid environments refers to plywood intended for use in environments characterized by a moisture content of 20°C and a relative humidity of the surrounding air exceeding 85% for only a few weeks per year. These conditions correspond to service class 2 of EN 1995-1-1. Such boards are suitable for use in service classes 1 and 2 of EN 3353. This type of plywood is suitable for protected exterior applications (e.g., behind cladding or under roof sheathing), but can also withstand short-term exposure to weather (e.g., during construction). It is also suitable for interior applications where the service humidity exceeds that of dry conditions.
• Plywood for outdoor use refers to plywood intended for use in climatic conditions that result in moisture content greater than service class 2. These conditions correspond to service class 3 according to EN 1995-1-1. This type of board is suitable for use in service classes 1, 2, and 3 of EN 335-3. This type of plywood can withstand weathering and exposure to liquid water or water vapor in a humid but ventilated location.

All plywood, regardless of composition factors (e.g., type, number of plies, and ply thickness), can be classified under this system based on its bending properties. As an alternative to the full-scale testing required by EN 789, the classification system can be used to derive characteristic values ​​for plywood by cross-referencing with EN 12369-2 the characteristic values ​​for each class listed in the tables "Bending strength classes for plywood" and "Modules of elasticity in bending classes for plywood" provided within the standard.

The lower limit values ​​for flexural strength and modulus of elasticity in bending given in the tables correspond to the 5th percentile values ​​based on the average values ​​determined for individual panels according to EN 310 and EN 326-2 and calculated according to EN 326-1. These values ​​should not be used for structural design. The determination of flexural properties is described in this standard.

For a given plywood, the four grades will be given in the following order:

• Strength in the longitudinal direction
• Strength in width direction
• Modulus in the length direction
• Module in width direction

Dimensional tolerances must be as specified in the EN 315 standard.

Bending properties should be determined on small test pieces according to EN 310 and calculated according to EN 326-1. According to EN 326-2, 5 percentile values ​​are determined from at least 30 panels of the same product type.

The EN 636 standard is essential because it provides clear, consistent quality and performance criteria, ensuring that plywood used in construction projects is safe, durable, and fit for purpose. The reasons for this standard's importance include:

• Standard performance classes: This standard divides plywood into three main classes based on its intended use and exposure to moisture:
  • EN 636-1: For dry conditions (indoor use with low humidity)
  • EN 636-2: For humid conditions (indoors with high humidity or temporary outdoor exposure)
  • EN 636-3: For outdoor conditions (permanent outdoor use)

This helps specifiers and builders choose the right type of plywood for the environment it will be exposed to.

• Increases safety and reliability: This standard specifies minimum performance standards (e.g., mechanical strength, moisture resistance), reducing the risks of: structural failures, material degradation, and costly maintenance or replacement.
• Supports regulatory compliance: This standard complies with the European Construction Products Directive (CPR). Products that comply with the EN 636 standard can carry the CE marking, demonstrating that they meet European Union requirements.
• Ensures comparability: With this standard, contractors and engineers can easily compare plywood products from different manufacturers on the basis of: strength class, joint quality and durability.
• Promotes sustainable construction: Standardization ensures that materials are suitable for long-term use, reducing waste and contributing to more sustainable construction practices.

Our organization, which has been supporting businesses across all sectors for years through a wide range of testing, measurement, analysis, and evaluation activities, has a strong team of employees who closely follow global developments in science and technology and are constantly improving themselves. In this context, we also provide testing services in accordance with the "EN 636 Plywood - Specifications" standard.