Zidi Yan

The Australian National Standard for the preservative treatment of wood (Standards Australia, AS/NZS1604.1) defines the penetration zone and the preservative retention that must be present in the penetration zone for each of six hazard classes.
For Hazard Class H3 (AS/NZS 1604.1) sawn structural members 35 mm thick or less, and of natural durability classes 2, 3, or 4 (AS/NZS 5604.2), the penetration zone is all sapwood plus 5mm from any (heartwood) surface (a heartwood percentage area limitation applies).
The Standard allows the use of chemical indicators to determine the extent of sapwood and heartwood as well as preservative penetration. Preservative penetration indicators change colour in the presence of certain levels of a specific active ingredient (usually copper in copper containing preservatives or zinc used as a tracer in light organic solvent (LOSP) systems).
However, interpreting penetration patterns is subjective, and the National Centre for Timber Durability and Design Life (NCTDDL) initiated a project intended to create a guide to help interpret penetration tests.
A survey was conducted with 43 selected Australian and New Zealand timber protection industry professionals, who were asked to interpret 20 sets of copper penetration test photographs.
This report presents the results received.

This report presents the first integrated update on an in-situ monitoring and analysis programme that investigates how moisture influences the durability and structural performance of mass timber elements in a subtropical building at the University of the Sunshine Coast’s Moreton Bay Campus. The project combines long term field data from embedded OmniSense sensors with upcoming laboratory tests to build predictive models and practical guidance for designers, builders, and facilities teams. 46 sensors using both shallow and deep screws were installed across CLT walls and ceilings and GLT beams and columns with coverage on all principal orientations and at multiple depths. Three data gateways were deployed, and while connectivity interruptions created several gaps, most sensors now provide a robust and continuous dataset from late 2024 to August 2025 for building location specific interpretation.

Across the monitored period the timber remained dry and resilient. Moisture content typically sat between 7 and 15 percent and never entered the biological risk bracket. Three wet periods (including Cyclone Alfred) around 10 March, late March to early April, and late April to early May lifted indoor relative humidity and dew point for a few days, yet moisture content stayed comfortably low and returned to baseline quickly.

Moisture dynamics were governed by indoor vapour conditions rather than by liquid water. Dew point rarely approached surface temperatures and condensation risk was low. Orientation affected timing and amplitude rather than safety. West faces showed slightly larger afternoon vapour peaks and slower recovery. South facing areas were cooler and a little more humid than the north. Depth of screw penetration affected timber moisture content readings more than air side metrics. In general, deeper screws recorded slightly higher and slower changing moisture that reflects inner lamella behaviour, while shallow screws captured quicker surface responses.

Location specific checks confirmed these patterns. Ground level sensors near glazing remained below 20 % and re-stabilised within three to five days after rain. Level 1 positions beneath the cool and freezer rooms showed small but coherent offsets, with the cool room side marginally cooler, more humid, and about 0.7 % higher in mean moisture. Level two beams along the south curtain wall were uniformly dry and stable. Corridor sensors showed the south side a little more humid and the end wall position the driest. No location showed evidence of liquid water ingress or sustained wetting.

The project now moves to strengthen coverage and deepen analysis. Priority actions are to restore all offline sensors and installed one additional gateway to enhance the signal coverage, maintain a daily health check on batteries and connectivity, and consider an onsite weather station to replace the 10 km proxy. The analysis plan will standardise correlation and lag studies and build event database for rain and humid periods. These steps will calibrate predictive models in the upcoming PhD programme and formalise alert thresholds, typical lags, and orientation and depth expectations. The expected outcome is a validated evidence base and practical recommendations that improve the moisture resilience of mass timber assemblies in Australian Southeast Queensland subtropical conditions and inform design and operational guidance for industry.

The viticulture industry in Australia, has millions of end-of-life (EOL) preservative treated timber posts which have been removed from vineyards either because they break during harvest at the soil interface or because the trellis they support is being upgraded or removed. Most winegrape growers stockpile these posts on site however they can potentially be reused or recycled. To determine how these EOL vineyard posts can be reused as part of a circular economy (CE) the condition and strength of the posts need greater understanding.
As part of the National Centre for Timber Durability and Design Life (NCTDDL), the Timber Circularity Project funded by the FWPA and industry partners, has quantified this resource in terms of numbers and assessed the treatment level for reuse in outdoor applications. This study aimed to assess whether reclaimed vineyard posts possess sufficient strength and stiffness for repurposing as smaller agricultural posts or other low-stress outdoor applications
The mechanical performance of a limited sample of EOL and new CCA-treated vineyard timber posts have been examined through comprehensive structural testing to determine the possibility for extending the life of the posts in further applications. Key parameters, such as density, maximum load, maximum displacement, Modulus of Elasticity (MoE), and Modulus of Rupture (MoR), were analysed to evaluate the suitability of the reclaimed posts for reuse.
The report outlines the assumptions and limitations of the testing as well as the findings, which show that despite some degradation the reclaimed posts retain the strength and stiffness required for agricultural fencing. Further research with larger sample sizes, known initial densities, and timber species data is recommended to support these findings and explore broader reuse potential in a transition to a circular economy.

The building and construction (B&C) industry remains one of the highest greenhouse gas emitting and resource intensive sectors globally. Despite the recent trend to use renewable carbon sequestering building materials, such as timber, a paradigm shift is needed to transition the B&C industry towards an ‘absolute zero’ circular economy. Design for adaptability (DfA) allows buildings and their components to remain in use for longer by responding to changing environmental conditions and occupant needs. This paper provides a review of design principles to enable adaptability for timber buildings through design for disassembly (DfD) and reuse, as well as a systematic review of reversible timber connection systems that enable DfA and DfD.

Fastener products are commonly exported to different continents, and it is important to understand their performance in local timber species and construction practices. This paper investigates the effects of cyclic moisture changes on the withdrawal performance of yellow-zinc and nickel-zinc coated European screws in Australian copper chrome arsenate (CCA) treated Southern Pine, up to a maximum of 24 cycles. A 68–78% loss of the initial withdrawal strength was observed after three cycles, but this was recovered after twelve cycles. Overall, screws lost at least 50% of their initial strength after 24 cycles, regardless of the treatment or fastener coating. The corrosion resistance of nickel-zinc screws in CCA-treated timber was superior to that of yellow-zinc screws in the first three cycles, but the difference disappeared as the moisture cycle number increased. In CCA-treated timber, the corrosion rates of yellow-zinc screws were 40% higher than those in untreated timber. Although nickel-zinc screws were relatively more corrosion-resistant than yellow-zinc screws, the strength loss caused by corrosion confirms that the selected screws are best suited for indoor use. Finally, following a comparative analysis of test results, some recommendations were made in this paper for future research.

This paper provides a novel insight into using reversible mass timber connectors in light-timber framed (LTF) construction to create dismountable, panelised LTF construction systems that enable adaptable building design and panel reuse in the context of a circular economy. The study presented in this paper focused on Australian LTF panelised construction:. A total of 10 IdeFix 304 connectors by SIHGA GmbH, and 20 M20 connectors by SHERPA Connection Systems GmbH were installed in Australian machine graded pine and subjected to monotonic tensile and shear loads to assess their feasibility in the given application. Two strength prediction models were evaluated in comparison to experimental results: Formulae given in the manufacturers’ European Technical Assessments (ETAs) and a prediction model adapted from literature. On average, the latter was more accurate in the given configuration. Considering the set goal of repeated assembly and disassembly, the connectors with a tight fit faced tolerance issues due to moisture fluctuations. Furthermore, rupture of the connector was observed in some instances, owed to higher screw withdrawal capacity in Australian timber. A reduction of the number of screws or their length is suggested to achieve a more ductile response with screw withdrawal. Finally, following comparative analysis of experimental tests and prediction models, recommendations were made for future design of novel LTF panel connectors in the context of disassembly and reuse.