Structural timber is not chosen by appearance alone
Structural timber is used where loads, spans, tie-downs, bracing or designed connections matter. This can include wall framing, roof framing, floor systems, lintels, beams, posts, joists and engineered members. Because structural timber is part of the building's performance, it should be selected according to the design and relevant professional requirements, not simply by what looks close in size.
For many residential and light commercial projects, a builder, designer, engineer or supplier may specify grade, size, treatment and engineered product type. The buyer's job is to order accurately, confirm documentation, protect the material and avoid substitutions that have not been approved. Even a small change in member type or grade can matter when the timber is doing structural work.
Structural timber categories
| Type | Common role | Planning requirement |
|---|---|---|
| Machine graded pine framing | Wall and roof framing in protected applications | Confirm grade, treatment, dimensions and straightness |
| LVL | Beams, lintels and engineered members | Use the specified product, orientation and installation method |
| Glulam | Feature beams, structural beams and architectural applications | Check engineering, appearance grade and protection |
| Hardwood structural timber | Posts, bearers, joists and heavy-duty applications | Confirm species, grade, durability and fixing requirements |
| Treated structural timber | Areas requiring protection from termites or exposure | Check treatment suitability for the project and environment |
Do not substitute without approval
Substitution is one of the biggest risks in structural timber supply. A product may look similar in size but have different strength, stiffness, treatment, durability or installation requirements. If the specified product is unavailable, the substitution should be checked by the relevant professional or design authority. This is especially important for engineered timber, beams, lintels, posts and members exposed to moisture or termites.
- Order from the approved plans, engineering schedule or builder instructions.
- Confirm the exact grade, size, treatment and product type.
- Check whether product data sheets or certificates are required.
- Protect timber from weather before installation.
- Keep labels and identification visible where possible.
- Do not notch, drill or modify structural members without approval.
Delivery and storage
Structural timber can be damaged by poor handling, moisture and uneven support. Long lengths should be supported correctly during unloading and storage. Packs should be kept off the ground, level and protected from rain. Engineered timber may have specific storage requirements that should be followed carefully. Water staining, swelling or distortion can create installation problems and may lead to disputes about responsibility.
On busy sites, structural timber should be stacked in a location that is accessible to the framing crew but protected from vehicle damage and theft. Label packs by stage or area where possible. If multiple sizes are similar, separate them clearly to reduce the risk of the wrong member being installed.
Fixings, connectors and installation details
Structural timber relies on the correct fixings and connectors. Brackets, hangers, bolts, nails, screws, straps and tie-down hardware are not all interchangeable. Some products require particular nail patterns or fastener types. Treated timber and outdoor applications may need corrosion-resistant hardware. Engineered products often include installation limits for holes, notches, bearing and orientation.
Better questions for structural timber orders
Ask the supplier whether the timber matches the nominated grade and treatment, whether lengths are available, whether engineered members can be delivered without damage, whether identification labels will remain attached and whether documentation is available. Ask the builder or designer whether substitutions are allowed and what process should be followed if supply changes.
Structural timber is worth planning carefully because errors can be expensive to correct. The best outcome is a clear order, approved substitutions only, protected storage and installation according to the relevant design and product requirements.