RAT Chat # 6 - Receiving H2 Framing Timber: What Every Manufacturer Should Know

Last month, Kersten and myself had the opportunity to learn more of the latest developments at the Timber Preservers Association of Australia (TPAA) forum in Brisbane. 

Preservative treated timber underpins the majority of the timber industry and a credible and reliable treatment industry ensures continued market access, performance and confidence in timber building products. 

For most frame and truss manufacturers, treated framing timber arrives every week. It is unloaded, checked, stored, docked and assembled into structural components. While these activities are routine, understanding what to look for when treated timber arrives can help maintain product quality, support compliance and ensure the durability of the product is preserved throughout manufacturing.

Start with the Treatment Brand

The first quality check should always be the treatment brand.

Under AS/NZS 1604, preservative-treated wood products, treated timber is required to be permanently marked with information identifying the treatment plant, Hazard Class and preservative system. It provides evidence that the timber has been treated in accordance with the requirements of the Australian Standard.

For manufacturers operating quality management systems, verifying treatment branding should be as routine as checking structural grade, dimensions or moisture content (a girl can dream). 

You can learn more here ► Preview: AS/NZS 1604.1:2021 | Standards Australia Store

Understanding H2

One of the most common misconceptions is that H2 refers to a particular chemical treatment. In reality, it is a performance classification.

The Hazard Class system specifies the durability performance required for the timber's intended service environment. H2 framing is designed for internal, above-ground structural applications and can be achieved using different preservative systems, provided they satisfy the penetration, retention and performance requirements specified by AS/NZS 1604.

You can learn more here ► Timber Treatment – TPAA

This performance-based approach allows preservative technologies to continue evolving while maintaining consistent durability outcomes in the build environment.

Why the Blue Colour?

The blue colour is an identification dye added during treatment. It allows treated timber to be easily distinguished from untreated material during manufacturing and construction. The blue colour is not an indicator of treatment quality, preservative concentration or treatment penetration.
Compliance is verified through controlled treatment processes, quality assurance testing and product branding, not colour intensity.

Looking After the Treatment

H2 framing is commonly produced using envelope treatment (as outlined in AS/NSZ 1604), where preservative is concentrated within the outer zone of the timber rather than through the full cross-section.
This is an efficient engineering solution because the treatment is designed specifically for the intended service conditions of internal framing. However, it also means manufacturers should avoid unnecessary removal of treated surfaces wherever practical.

Routine cutting associated with frame and truss manufacturing are expected within the treatment system. However, significant machining operations such as deep routing, excessive notching or extensive rebating can expose untreated timber beneath the treated envelope. Where substantial material has been removed, manufacturers should refer to the treatment supplier's recommendations regarding supplementary preservative application.

Good Storage Matters

Although preservative treatment improves biological durability, it does not eliminate the need for good timber storage practices.
Treated framing should be stored clear of the ground, adequately supported to prevent distortion, protected from unnecessary wetting where practical, remains well-ventilated and handled in a manner that minimises mechanical damage. Good storage practices help maintain dimensional stability, reduce unnecessary moisture fluctuations and ensure timber enters production in the condition intended by the supplier.

Quality Starts Before Manufacturing

Receiving inspections provide an opportunity to identify potential issues before manufacturing begins.

Manufacturers should confirm:
•    The treatment brand is present and legible.
•    The specified Hazard Class matches the intended application.
•    Structural grade and product identification are correct.
•    Packs have not been excessively damaged during transport.
•    Storage conditions maintain product quality prior to manufacture.

These simple checks form part of an effective quality assurance system and help minimise downstream issues during production.

More Than a Compliance Requirement

Preservative treatment is one component of Australia's engineered timber durability system. Together with structural grading, moisture control, responsible manufacturing and compliance with Australian Standards, it enables timber framing to deliver reliable long-term structural performance across a wide range of Australian environments.

For frame and truss manufacturers, understanding what treatment branding means, how modern treatment systems work and how to care for treated timber after delivery is more than good practice. It is an important part of protecting product quality, supporting compliance and maintaining confidence in Australia's most sustainable construction materials.

If you would like to learn more, feel free to get in touch on 0431 088 918 or at rhianna@ftma.com.au.

You can also reach out directly to TPAA for any queries relating to timber treatment through their contact page. Contact – TPAA