IRG Documents Database and Compendium


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Effect of Moisture Cycles and Timber Treatment on the Performance of Screwed Connections
2023 - IRG/WP 23-20694
The impact of moisture in timber structures is associated with the deterioration of timber, and loss of mechanical performance. Methods have been developed to treat timber using chemicals to inhibit deterioration, however, water intrusion has much more immediate effects on the mechanical properties of timber associated with swelling and shrinkage of the wood. The effects of moisture on the mechani...
L Yermán, M Xiao, Z Yan, L-M Ottenhaus


Moisture performance of wooden shingles tested on the Golobar cable yarding
2023 - IRG/WP 23-20704
Wood is a traditional roofing material in Europe and other parts of the world. In the 17th century, wooden roofing was generally used on more important buildings, but today it is mainly used on huts and houses in the Alpine regions. As wooden roofing is expensive, we investigated the possibility of extending the service life of the roofing through material selection and details. The roof of the Go...
M Humar, B Lesar, D Kržišnik


Control of Asian subterranean termites Coptotermes gestroi (Blattodae: Rhinotermitidae) by a new generation bait system with vegetal extracts-diflubenzuron mixture
2023 - IRG/WP 23-30797
The efficacy of anti-termite bait pebble dosed at 0.3% w/w of Diflubenzuron, and Chitin Synthesis Inhibitor (CSI) and 0.6% w/w of vegetal extract from Berkem Biosolutions®, was evaluated in the laboratory on the Asian subterranean termite Coptotermes gestroi (Wasmann). Four concentrations 33.3%, 50%, 50% bis and 100% as well as two neutral matrices, were used in two in-house developed test method...
F Chopinet, D Messaoudi


Biological durability and wood-water interactions of sorbitol and citric acid modified wood – Effects on the expected service life
2023 - IRG/WP 23-40960
A high level of research activities on sorbitol and citric acid (SorCA) modified wood has been recognized in Europe over the last few years. As this treatment is close to entering an industrial-scale production, it is of interest to investigate how such treated wood performs upon long-term outdoor exposure. Hence, in this study Scots pine (Pinus sylvestris L.) sapwood was modified with aqueous sol...
K Kurkowiak, L Emmerich, H Militz


Impacts of elevated moisture levels and subsequent drying on screwed
2023 - IRG/WP 23-40970
Mass timber (glue-laminated timber, cross laminated timber (CLT) and laminated veneer lumber) are increasingly used in mid-to high rise structures in Australia where the climate is mainly sub-tropical with elevated moisture levels and high termite risk. Moisture intrusion poses a major challenge anywhere but becomes more critical under these conditions. Untreated/non-durable materials are consider...
C M T Roder, C D Gerber, J J Morrell


Failure characteristics of thermally modified poplar wood subjected to mechanical tests
2023 - IRG/WP 23-40983
Poplar (Populus spp.) are among the fastest growing timber species and have been widely planted for use in plywood, composites, pallets, furniture components and paper production. However, the low density of the wood limits many structural applications and the wood has little resistance to biodegradation. Thermal modification represents one approach to improving durability by changing the moistur...
E Bari, M Ghorbanian Far, N Moradi, J J Morrell, G Daniel, B Mohebby, R Hosseinpourpia, M Humar


Prevention of termite tubing on foam insulation materials
2024 - IRG/WP 24-11039
Foam insulation products have been shown to be damaged by termites who can readily tunnel within it and use it as a conduit within structures. Different types of commercially available foam insulation were tested to see if they could support termite (Coptotermes formosanus, Shiraki) tunnelling on or within them and whether they could be used as a conduit to access a wood food source placed above i...
Q Wu, J Curole, J D Lloyd


Intra-species variability of moisture dynamics in wood
2024 - IRG/WP 24-11040
Moisture dynamics of wood and wood-based materials play a major role in wood durability against different decay organisms. Their impact becomes particularly evident when wood is exposed, but not permanently wet. To date, however, this has only been taken into account indirectly and therefore inadequately when testing the durability of wood. While test methods are available, for example to determin...
C Brischke, H Purps, L Emmerich


Wood above ground project – Results and future plans
2024 - IRG/WP 24-11041
In 2000, the Danish Technological Institute (DTI) initiated an extensive study to investigate the natural durability of wood. The study involved exposing wood in various orientations to assess its performance. A total of 35 wood material types were exposed at DTI test site in Taastrup, Denmark. Moisture content (MC) was measured through weighing for the initial five years, decay was assessed follo...
A W Christof, R Digaitis, P Fynholm, J Stenbaek, N Morsing, B Lindegaard


Efficacy performance of Pea Extract as bait toxicant for termite control in Reunion Island
2024 - IRG/WP 24-11050
This study was carried out to determine the toxicity of Pisum sativum L., extract (Pea Extract) for the subterranean termite, Coptotermes gestroi (Isoptera: Rhinotermitidae). Yellow field peas (Pisum sativum L.) are particularly rich in protein. A solid-liquid hydroalcoholic extraction process was employed on the dried form of pea seeds to obtain one particular peptide PA1b (Pea Albumin 1, subunit...
J Vuillemin, D Messaoudi, A Robert, P da Silva


EMC as a quality control parameter for thermally modified wood
2024 - IRG/WP 24-20720
While standards for quality performance of treated wood have been in place for many years, none have been developed for modified wood such as thermally modified wood (TMW). Only in one case has TMW been listed in 2018, by the Nordic Wood Preservation Council (NWPC). A key component of a quality system is its control parameters, i.e. the metrics that are to be measured and controlled. Existing m...
P Klaas, J T Lauridsen


International joint field trial on the moisture performance of wood – Set up and first results
2024 - IRG/WP 24-40996
Wood durability to decay stems from its inherent resistance to fungi resistance to fungi. In this regard, wood's ability to withstand moisture uptake plays an important role as the lower threshold for wood decay is a moisture content of 25%. However, the aspect of moisture resistance is not yet sufficiently emphasized as a durability factor, both in the assessment of durability as a material prope...
C Brischke, et al. (33 co-authors)


How personality traits influence the perception of fungal decay in a wooden cladding – A survey in three Modelling wood moisture content in outdoor conditions from measured data
2024 - IRG/WP 24-41002
This study examined perceptions of fungal decay damage on wooden cladding across Norway, Sweden, and Germany. The majority of respondents across all countries did not find the fungal decay damage in question acceptable, with the least acceptance in Norway. This could be due to Norway having the highest frequency of wooden residential buildings and the most experience with maintaining wooden claddi...
G W Gustavsen, G Alfredsen, P B van Niekerk, J Niklewski, C Brischke


Modelling the service life of wood in ground contact – Verification of remotely sensed soil data from the reanalysis dataset ERA5-Land using in-situ measurements at a test site of utility poles in Eastern Norway
2024 - IRG/WP 24-41003
This study compared soil moisture and temperature estimates from the 5th European reanalysis (ERA5-Land) dataset with in-situ measurements to assess the accuracy and applicability of ERA5-Land data for modelling the service life of wood in ground contact. The ERA5-Land soil temperature estimates showed a moderate correlation with the in-situ temperature measurements (Spearman’s ρ of 0.73) and a...
U Hundhausen, P B van Niekerk, B Marais


Modelling wood moisture content in outdoor conditions from measured data
2024 - IRG/WP 24-41005
Sustainable use of wood requires an understanding of expected service life, particularly when the material is exposed to outdoor conditions and, thus, fungal decay. Since moisture is the primary vector for fungal decay, accurate moisture prediction is a key component in service life assessment. For this purpose, the present study leverages existing measured data for linear regression of in-field m...
J Niklewski, P B van Niekerk, L Meyer-Veltrup, J Sandak, C Brischke


Analysis and performance of spruce alternative species and discarded wood for windows production
2024 - IRG/WP 24-50386
Climate change is having a significant impact on European forestry, particularly on the softwood species used for window frames. This study investigates potential replacement tree species for spruce (Picea abies), the predominant material for window frames. We evaluate Douglas fir (Pseudotsuga menziesii), Scots pine (Pinus sylvestris), thermally modified poplar (Populus nigra) and discarded silver...
B Lesar, J Levanič, M Humar, A Treu


Determining the minimum water vapor permeability of exterior wood coatings by means of hygrothermal and decay models
2024 - IRG/WP 24-20717
The objective of this study was to determine the minimum water vapor permeability of exterior wood coatings for log homes using hygrothermal and decay modeling. The approach is based on a worst-case scenario assumption, namely a moisture trap at a given wood moisture content in a coated wall log. The minimum limit of vapor permeability of the coating system was determined by simulating the time re...
U Hundhausen, S Ullah, D Kraniotis


Fungal degradation of oak timber bridges
2025 - IRG/WP 25-11058
Wood is increasingly recognised as an eco-friendly building material, but its organic nature makes it vulnerable to degradation, especially in outdoor applications exposed to moisture. This study investigates wood-decaying fungi affecting oak timber bridges in Hanover, Germany. The study aimed to identify the fungal species using culture-independent methods and to examine the impact of poorly exec...
L Schrader, J Trautner, C Brischke


Entomopathogenic organisms: Host-pathogen interactions
2025 - IRG/WP 25-11059
The management strategy of wood attacked by wood-eating insects has been until now by the application of insecticidal products used as biocides and/or repellents, or using physical treatments. This paper describes the use of entomopathogenic organisms (viruses, bacteria, fungi and nematodes), normally used in agricultural systems, in order to study their possible transfer to wood-decay insects. ...
M T Troya, S Santos, L Robertson


DURALARCH – Suitability of selected coloured coniferous heartwoods of different origin for their use in outdoor applications
2025 - IRG/WP 25-11064
For outdoor above-ground applications with high demands on biological durability, there are only a few softwoods available that also have high density and strength characteristics. One of the most important timbers with these material properties is Siberian larch (Larix sibirica, Larix gmelinii), which is available in sufficient quantities due to its large distribution area. Imports of Siberian la...
C Brischke, J Appelt, G Koch, S Majer, M Nopens, R Stirling, D Wong


Evaluating the Efficacy of Arnica Extract-Based Termiticide from Berkem Biosolutions® in Subterranean Termite Control: A Comprehensive Laboratory and Four-Year Field Study
2025 - IRG/WP 25-20731
Subterranean termites pose significant threats to wooden structures. This study evaluated the efficacy of a bio-based termiticide product containing Arnica extract from Berkem Biosolutions® in controlling subterranean termites in both laboratory and field conditions. The laboratory assessments utilised “the Bottle H” test unit, adhering to the Japan Wood Preservation Association (JWPA) standa...
D Messaoudi, S Khoirul Himmi, D Tarmadi, I Guswenrivo, S Yusuf


Mitigating the risk of decay in CLT buildings affected by trapped construction moisture using a diffusible borate preservative
2025 - IRG/WP 25-20735
Cross-Laminated Timber (CLT) is also known as a mass timber construction material. It is fabricated by gluing together multiple layers of timber lamellae with each layer oriented perpendicular to the one below it. This enhances strength, stability and dimensional rigidity. CLT is seen as an excellent ‘low carbon’ alternative to using steel and concrete and is growing in popularity as a sustain...
J R Williams


Influence of incising methods and wood moisture content on ‘deep penetration treatment’ in Japanese cedar and larch
2025 - IRG/WP 25-20749
To expand applicability of ‘deep penetration treatment’, a solvent-borne and non-pressure treatment that is commonly coupled with roller-type incising using a flat blade, we investigated drill and laser machining as alternative incising methods and examined the influence of wood moisture content on the preservative penetration. Various incising methods were applied to heartwood of Japanese ced...
S Taira, T Miyauchi, S Isaji, H Matsunaga


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


Moisture uptake in CLT during the construction phase: real construction conditions versus specimens exposed to environment
2025 - IRG/WP 25-41019
The rapid growth in the use of Cross-Laminated Timber (CLT) in construction highlights the need to address durability concerns, particularly in regions with less experience in Mass Timber Construction and favourable climatic conditions for the biological degradation of wood, such as Mediterranean countries. A lack of awareness and deficient construction management can negatively impact the public ...
D Lima, S Duarte, J M Branco, L Nunes (†)


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