IRG Documents Database and Compendium


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Performance of untreated timbers in above ground decking tests: Preliminary results from an international collaborative trial
2019 - IRG/WP 19-10940
The ability to accurately predict wood decay risks under varying environmental conditions has long been of interest to timber users. Accurate predictions are difficult owing to the myriad of variables associated with the decay process including wood species, wood inhabiting organisms, timber building element design and environmental conditions. Despite these difficulties, decay predictions have be...
L P Francis, J Norton, E Melcher, A H H Wong, J Kok Lai, M Klamer, M J Konkler, J J. Morrell


Visual assessment of longitudinal wheel timbers and assessing the feasibility of extending wheel timber service life in the UK railway network
2019 - IRG/WP 19-20651
Timber has been a versatile building material for centuries and during the start of the Railway Age in the nineteenth century it was in considerable demand for use in the railway network, particularly bridge building. Timber is still in service and widely used throughout the UK railway network. The resilience and favourable strength to weight ratio and its relative ease of fabrication make it an...
J R Williams


Durability classification of preservative treated and modified wood
2019 - IRG/WP 19-20659
EN 350 (2016) allows formally to determine durability classes (DC) for wood products and wood-based materials, which was previously only possible for untreated wood in the form of natural durability. In a first study, the University of Goettingen carried out the durability classification of chemically modified (modified with 1,3-dimethylol-4,5-dihydroxyethyleneurea, DMDHEU) and preservative-treate...
S Bollmus, L Bachle, C Brischke, H Militz


Protecting Sustainable Wood Infrastructure ̶ Improving the Performance of Poles, Piles, Ties & Timbers with Dual Treatments
2019 - IRG/WP 19-30735
Wood is by far the best structural material in terms of environmental impact, as shown by a number of LCA studies. This environmental impact superiority can be improved if the longevity of the commodity is extended. The main durability concern in large cross-section treated materials is the susceptibility of the heartwood to decay, as it is not typically treatable using traditional methods. This ...
J Lloyd, A Taylor, C Brischke, N Irby, M Manning


Treatability of native and exotic alternative timber species
2019 - IRG/WP 19-40864
The service life of moderately durable species can be extended significantly if the challenge of effective treatment of refractory wood species can be overcome. Along with preservative effectiveness, the performance of preservative in treated wood depends on factors such as retention and penetration in treated wood, the wood anatomy, the uniformity of penetration and micro-distribution within the ...
D Page, T Singh


Longterm Performance of Treated Timbers in Marine Exposures
2020 - IRG/WP 20-10969
The performance of preservative-treated or modified woods in marine exposures was evaluated at test sites in Newport, Oregon, USA and Brisbane, Queensland, Australia. All samples have exhibited excellent performance at the Newport, Oregon site, while attack was more aggressive at the sub-tropical Brisbane site. Acetylated wood as well as samples treated with 7.3% chromated copper arsenate (CCA-T...
M Konkler, A R Zahora, J Norton, J J Morrell


Development of procedures for sampling, testing, and classification to determine the biological durability of wood and wood products
2020 - IRG/WP 20-20676
This paper informs about a research project, which deals with several shortcomings and a lack of clarity within EN 350:2016. The project started in January 2020, will run for 3 years, and is operated by the Institute of Wood Technology Dresden (IHD) and the University of Goettingen (UGOE). Determination and classification of durability of wood and wood products against wood-destroying organisms ...
W Scheiding, K Jacobs, S Bollmus, C Brischke


Sterilization of Large Timbers during Preservative Treatment: How Quickly We Forget
2020 - IRG/WP 20-40902
Air seasoning is a common method of moisture management in utility poles and is done de facto during pole storage prior to treatment. However, extended air drying prior to treatment encourages fungal attack and can facilitate establishment of decay fungi in poles before a protective preservative barrier is applied. This problem can be mitigated by proper air-seasoning methods coupled with heat ste...
G Presley, J Cappellazzi, M Konkler, K Maguire, R Nelson, J J Morrell


Susceptibility of selected Australian commercial timbers to West Indian drywood termite Cryptotermes brevis
2023 - IRG/WP 23-11003
West Indian drywood termite (Cryptotermes brevis) is a globally distributed timber pest and is invasive in Queensland, Australia, causing widespread damage to structures and large economic impacts in control and repair costs. Despite this, the knowledge of which specific timbers are susceptible to attack is limited and requires investigation. Two six-week feeding trials were performed, exposing se...
W Haigh, R A Hayes, B Hassan


Long-term Performance of Treated Timbers in a Sub-tropical Marine Exposure
2023 - IRG/WP 23-11015
The long-term performance of preservative-treated and modified wood in marine exposures was assessed in Brisbane, Queensland, Australia. This report describes the final destructive assessment of the surviving Australian panels after 11 years of exposure. This site presents the potential for attack by shipworms (likely Bankia spp.), pholads (Martesia striata), Limnoria and Sphaeroma terebrans. Mos...
E L Galore, J Norton, A Zahora


Laboratory durability testing of preservative treated wood products – first attempts and observations
2023 - IRG/WP 23-20697
In the past, durability classes (DC) had been assigned to wood species, sometimes also to homogenously modified wood-based materials such as thermally modified wood. More recently, some standards allow for classifying the biological durability of chemically modified wood, preservative treated wood and wood composites. Even treated products may be subject to durability classification, but necessary...
C Brischke, M Sievert, M Schilling, S Bollmus


A comparison of methods – how to achieve a robust and conclusive durability classification of wood
2025 - IRG/WP 25-11063
The biological durability of wood is a relative and unitless size, and therefore wood species and wood-based materials are assigned to durability classes (DC). In Europe, such classes are based on a variety of measures, which can be absolute or relative to a non-durable reference species. The aim of efforts to develop and standardise methods for determining biological durability should be to ensur...
C Brischke


NTR classified preservative-treated laminated wood
2025 - IRG/WP 25-20750
NTR is a trusted quality labelling system used for the classification and quality control of wood products that have been treated with preservatives or modified. These labels are issued by the Nordic Wood Preservation Council (NWPC) and in recent years, producers of glued laminated timber as well as building material suppliers have shown increasing interest in NTR classification for glued laminate...
J Jermer, F Westin, R Digaitis


Contribution of naturally durable wood use to Circular Economy - Understanding the classification system of natural durability and its variation within wood species
2025 - IRG/WP 25-50411
Total wood demand is shown by FAO to increase 49 percent between 2020 and 2050, regardless of deteriorating conditions such as deforestation and degradation due to fire and biological damages. Demand for wood as a building material is also projected by UNEP to increase significantly to 300 Gt in 2040. To address this situation, extension of the service life and re-use of wood are expected to make ...
K Yamamoto, T Osawa, R Noda


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