Engineered Wood Products (EWP) specifications for Australian projects

What engineers need to know about engineered wood products

Engineered wood products cover a range of manufactured structural materials, and each behaves differently from sawn timber in ways that affect specification decisions. LVL is made by rotary-peeling logs into thin veneers, drying and grading them, then bonding them with structural adhesive under heat and pressure with all grain aligned in the longitudinal direction. The result is a product with lower variability than sawn timber and consistent strength and stiffness across long lengths and deep sections. Wesbeam, Australia's only LVL manufacturer, produces billets up to 1,200 mm wide, enabling sections as deep as 600, 900, or 1,200 mm on special order, alongside standard depths from 70 mm up to 450 mm and widths from 35 to 75 mm.

Glulam (GLT) uses solid timber laminates or finger-jointed boards with the grain running in one direction, assembled vertically into a beam. Most manufacturers produce them with a camber (labelled GLC) to counteract dead-load deflection on long spans, or as straight beams (GLS) suited to cantilever applications. Glulam grades from GL8 to GL18 appear in AS 1720.1, though in practice GL10 and GL13 are the most reliably stocked grades nationally, with availability varying by state and supplier. Unlike LVL, glulam is often used in exposed or feature applications where visual grading options can be specified.

I-joists pair an LVL or solid timber flange with a structural web, typically OSB or plywood, to form the familiar I-shape. They provide span capacity comparable to solid LVL joists at significantly lower weight, and the web allows large service penetrations for plumbing, ducting, and electrical runs. Depths in the Australian market typically range from 200 to 400 mm with flange widths from 40 to 90 mm.

A practical guide for choosing between product types: LVL and I-joists suit floor joists and rafters; LVL and GLT are the standard choice for structural beams; sawn pine covers standard wall studs, with LVL or GLT appearing in high-load or off-site modular applications. Treatment levels should either be explicitly called out on drawings, with the engineer taking responsibility for the choice, or left as a note specifying treatment to suit the exposure class, leaving final selection to the builder or supplier with knowledge of the site conditions.

Why LVL specification is different from glulam or sawn timber

Glulam grades and their characteristic values are defined in AS 1720.1. Sawn timber grades such as MGP10 and MGP15 are similarly standardized, and the standard's appendix tables provide the design properties directly. LVL is different: characteristic values for structural LVL must be obtained from the manufacturer, and there is no standard definition of a grade such as LVL 13 in the code.

In practice, multiple suppliers market products under the LVL 13 label, including Wesbeam's e-beam, plus products from Meyer, ICI, Tilling, and Dinidis. Each of those products may have the same modulus of elasticity (13,000 MPa) but different published bending strengths, shear strengths, and other characteristic values. Serviceability checks often govern residential spans, which is why engineers have historically referenced the e-value as shorthand. The problem is that a design also requires checking bending strength, shear, bearing, and sometimes compression or tension, and those values are not interchangeable across suppliers.

The capacity factor for LVL in AS 1720.1 is higher than for sawn timber because the manufacturing process offsets defects across many veneer layers, producing a statistically more consistent product. Substituting sawn-timber characteristic values into an LVL design, or failing to specify which LVL bending strength was used in the calculation, eliminates that benefit and leaves the design open to substitution with a product that may not satisfy the strength checks.

The three compliant options for specifying LVL

Tom Rickerby outlined three practical approaches that each satisfy the requirement for an engineered specification.

The first is to nominate a specific product and brand, for example 240 x 63 Wesbeam e-beam LVL. This gives all parties downstream - including procurement, frame and truss plants, and builders - a defined set of structural properties to match or exceed. The procurement team takes responsibility for ensuring the supplied product either matches the specified brand or provides equal or better design properties.

The second approach is to specify a product size and provide a table of acceptable equivalents. Volume builders with multiple preferred suppliers use this method: the drawing notes or a specification table lists two to five products from different manufacturers, each with published characteristic values the engineer has verified against the design. The builder or supplier can then choose any product from the list.

The third option is to define minimum structural properties directly in the drawing notes or specifications table. The engineer lists the minimum bending strength, shear strength, modulus of elasticity, and any other properties used in the design. Any product that meets those criteria is acceptable, regardless of brand. Tom suggested that for most residential and light commercial spans, an LVL with a short-term modulus of 13,200 MPa and a bending strength of approximately 45 MPa will cover the majority of situations.

A strutting beam example illustrates the risk of vague specification. An unrestrained strutting beam in a roof structure is prone to buckling, which can govern the bending capacity check rather than stiffness. Tom demonstrated in Calcs.com that a 240 x 45 LVL beam designed at 99 percent bending capacity using a 50 MPa product would fail if the procured product had a bending strength of 44 or 40 MPa, which is within the range of products marketed as LVL 13. If the drawing only stated "LVL e13" and the supplier procured a different product, the engineer may be found responsible in any subsequent dispute because the specification did not define what was required.

Practical limits: product availability and what to check before specifying

The grades listed in AS 1720.1 do not always reflect what is reliably available. For sawn timber, MGP10 in depths from 70 to 240 mm is widely stocked at timber merchants and frame and truss plants across most regions. Once depths reach 290 mm, or grades rise to MGP12 and MGP15, availability drops sharply, particularly in regional areas. Higher grades depend on denser, more mature timber, which is increasingly limited as forest resources change. Specifying an MGP15 section that a supplier cannot source creates project delays and may prompt unauthorized substitution.

The same principle applies to glulam: GL8 through GL18 grades appear in the standard, but GL10 and GL13 are the grades consistently available in most states. Some manufacturers produce proprietary grades and publish characteristic values for those products on their websites. The practical takeaway is to check with the supplier, framing contractor, or frame and truss plant before locking in a specification, particularly on regional projects.

For LVL, a similar check applies. Not all LVL depths or grades are stocked in every region. Confirming availability before issuing drawings, and where possible specifying products that multiple suppliers can provide, reduces procurement risk and helps the project run more smoothly.

LVL in bushfire zones, exposed conditions, and notched members

LVL can be used in all BAL zones when designed and detailed to AS 3959. Protection requirements increase at higher BAL ratings and may include cladding, flashings, or other shielding rather than changes to the LVL product itself. LVL is available up to H3 preservative treatment, covering above-ground exposure to periodic wetting. Applications requiring H4 treatment, such as in-ground contact, are generally better served by sawn pine products.

For frames exposed to the elements during construction, timber absorbs moisture and will swell. The glue bond in LVL is required to meet Type A bond specifications, meaning it is waterproof and will not degrade from wetting. The structural risk from prolonged wet exposure is biological decay, which depends on how long moisture content stays above approximately twenty percent. A visual inspection after the timber has dried back to normal moisture levels is the standard practice for assessing whether the material remains sound. Engineers need to apply judgment here because AS 1720.1 does not specify degradation timelines for construction exposure.

For notched and tapered LVL members, Wesbeam has tested splayed cuts down to 90 mm regardless of the full section depth, and these are covered in the published span tables for the e-beam product. For other notching or tapering scenarios, Appendix E of AS 1720.1 provides detailed design guidance covering both notched and tapered members. Engineers specifying LVL for roof members with birdsmouth or splay cuts should work through Appendix E and confirm compliance against the specific product's characteristic values rather than applying sawn timber rules.