Exterior Plywood
(3 Products)Exterior Hardwood Plywood provides a robust, high-performance solution for structural and non-structural applications where exposure to moisture is a primary concern. Engineered with a Class 3 glue line, these hardwood sheets offer exceptional stability and durability for demanding external environments and permanent weather exposure.
Understanding Exterior Plywood
Exterior Hardwood Plywood is a high-grade structural panel manufactured from thin layers of hardwood veneer glued together at right angles. This cross-laminated construction ensures superior strength-to-weight ratios and dimensional stability, making it far less prone to warping or splitting than solid timber when exposed to fluctuating moisture levels.
The specific range available is defined by its Class 3 bond, which is specifically engineered for exterior use. Unlike standard interior boards, these panels utilise a phenolic or equivalent weather-resistant resin that maintains the integrity of the board even in damp or humid conditions. The hardwood species used provide a denser, more impact-resistant surface compared to softwood alternatives, suitable for both permanent construction and high-traffic temporary works.
When used in external environments, the longevity of these panels is further enhanced by appropriate edge sealing and surface treatments. This ensures the hardwood core remains protected from water ingress, maintaining the structural performance of the building envelope over time.
Material Range
- Class 3 Hardwood Plywood: High-performance structural panels available in core thicknesses of 9mm, 12mm, and 18mm, designed for applications where moisture resistance is critical.
Performance Benefits
- Moisture Resistance: Utilises a Class 3 glue line specifically formulated to prevent delamination in damp, humid, or exposed outdoor conditions.
- Structural Integrity: The cross-banded hardwood construction provides high load-bearing capacity and excellent screw-holding properties.
- Durability: Resists impact and mechanical wear more effectively than softwood equivalents, extending the service life of the installation.
Typical Applications
- External Wall Sheathing: Providing a rigid, structural skin for timber frame constructions and outbuildings.
- Roof Decking: Serving as a stable substrate for felt, GRP, or EPDM roofing systems.
- Soffits and Fascias: Used in roofline applications where the board is shielded from direct rain but exposed to high levels of ambient moisture.
Vehicle Linings: Providing a durable, moisture-resistant floor or wall lining for vans and trailers.
Specification & Standards
- BS EN314-2 (Class 3): Specifies the requirements for bonding quality in plywood for use in exterior conditions.
- BS EN636-3: The standard for plywood performance requirements when used in external applications.
- BS EN13986: The European standard for wood-based panels used in construction, defining health, safety, and energy-saving requirements.
Related Materials and Construction Uses
Exterior Hardwood Plywood is a fundamental component of the building envelope and is frequently integrated with breathable membranes and vapour control layers to manage moisture within a wall or roof cavity. In roofing applications, these panels act as the primary substrate for waterproof coverings, including cold-applied liquids and high-performance membranes.
For projects requiring different performance characteristics, these Class 3 panels are often used alongside other Plywood Sheets. While this range is dedicated to exterior use, Hardwood Plywood with Class 2 bonding may be more suitable for internal humid environments where direct weather exposure is not a factor. Proper installation should always involve the use of stainless steel or galvanised fixings to prevent corrosion and staining of the hardwood face.
Frequently Asked Exterior Plywood Questions
How Is Exterior Plywood Graded?
Exterior plywood is marked with an "X" to denote its intended use, and the construction grade is indicated by the first two letters of the label.
"A" grade is the highest quality and is used for high-end applications, while "CDX" grade is a more affordable, construction-grade option that's still sturdy and reliable.
What Are The Different Types of Plywood Grades?
Plywood is graded into 4 primary groups:
- Class 1 – Strictly internal
- Class 2 – Interior grade of humid conditions but must be sealed
- Class 3 – Exterior grade but must be sealed (outdoor use)
- BS10 88 – Marine Plywood
What Is Cross Graining?
Hardwood plywood is an engineered wood composed of cross-grained thinly sliced wood veneers.
Cross-graining is the practice of orienting the wood grain of each plywood layer at right angles to the one below it. This alternating criss-cross pattern is behind plywood's impeccable strength and rigidity.
There are a few key reasons why cross-graining is so integral to plywood's overall strength:
- It helps to distribute weight more evenly across the surface of the material. This is because each layer is supporting the one above it, rather than all the weight being concentrated in one area.
- Cross-graining makes plywood less likely to warp or deform over time. When all the grain is going in the same direction, it is easier for the plywood to bow or twist out of shape. But when the grain is alternating, it prevents warping, making it much more difficult for the plywood to deform.
- Cross-graining gives plywood added strength in both tension and compression. This means that it can withstand more force without breaking or sagging.
What Is WBP Plywood?
The term "WBP Plywood" (which stands for "Weather and Boil Proof") refers to the type of glue that is used to bond the layers of wood veneer together.
This terminology has been superseded by the EN314 and EN636 classifications, which define the bonding quality of the adhesive and the standards to which the plywood will perform.
All of our general-use hardwood birch plywood sheet materials (made from birch veneers) meet level 2 under these classifications, which means that they are suitable for use in humid conditions, and can be used outside if treated with an appropriate preserver and sealer.
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