Specification of EWP’s

In construction, ensuring the structural performance of a project begins with the careful selection of engineered wood products (EWP). Incorrectly specified products can lead to complications, ranging from project delays to performance issues. To prevent such issues, it is crucial to follow clear guidelines and use precise specifications when choosing materials.

The Right products

Structural performance starts with choosing the right timber or EWP products. Incorrectly specified products may lead to unexpected project complications and, in some cases, serious consequences.

While factors such as design requirements, load conditions, product availability, and builder preferences influence product selection, we can follow established guidelines to ensure optimal performance and compliance. While the below table is by no means a hard and fast rule, it does give designers a quick reference as to what products are typically used in different application.

LVL Grades

Commonly, engineers will call up generic LVL names such as ‘E13 LVL’ on drawings. LVL grades are not defined in the Australian Standards. They’re manufacturer-specific, and the properties can vary significantly between suppliers. The “E value” being reference will refer to the average short term Modulus of Elasticity, which allows engineers to check the stiffness requirements (how much a beam deflects)

In structural design, we’re checking bending strength, shear strength, sometimes compression, and tension, and more – not just stiffness. This is where it becomes critical to recognise that different manufacturers publish different sets of characteristic values, even for products marketed as ‘E13 LVL’ or similar.

Characteristic values for structural LVL shall be obtained from the manufacturer. View Wesbeam’s e-beam LVL Design Criteria document for an example of what’s needed for compliant structural designs.

Correctly Specifying LVL

There are several methods by which structural engineers can ensure that they are correctly specifying LVL in their designs.

1. Specifying a brand and product.
   For example, “240 x 63 Wesbeam e-beam LVL”
   This is the most direct option as it ensures that you’re designing and detailing around known, published values. At the point of supply, the responsibility is then with the procurement team or wholesaler to ensure you get this product, OR one that has equal or better design properties.
    
2. Specifying a product and give a range of acceptable options.
   For example, ‘240 x 63 LVL – refer to table for options’.
   This allows for a few similar, widely available products with published characteristic properties – and the builder or supplier can choose from those, so long as they meet the performance requirements you’ve accounted for.
    
3. Specifying the minimum structural properties.
   For example: ‘240 x 63 LVL – refer to table for minimum structural properties’,
   This can be followed by a table that includes bending strength, shear strength, “E value”, bearing strength etc. This approach gives you flexibility, but you still control the structural performance – meaning substitutes in a different brand can still meet your design criteria.

While flexibility is possible, clarity is essential. Simply specifying "E13 LVL" without context is insufficient. Engineered wood products have precise, engineered specifications that ensure proper performance and compliance.

The Risk

Incorrect product specification can lead to unexpected project complications, including the supply of unsuitable materials and failure to meet required strength properties.

To avoid costly errors and ensure the structural integrity of a project, it is essential to specify engineered wood products with precision.

Clear, accurate, and detailed specifications enable proper material selection and guarantee that all design criteria are met. Following best practices and leveraging detailed specification safeguard against risks and achieve optimal project outcomes.