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A New Decay Hazard Map for North America Using the Scheffer Index
2008 - IRG/WP 08-10672
Wood decay experts in the USA and Canada use the Scheffer Index for above-ground wood decay potential to decide among design and treatment options to ensure the durability of wood construction. This paper provides an updated North American decay hazard map and includes data on Central America. Index values calculated from recent climate data are higher than published values due to directional or cyclical climate change. Compared to previously published maps there is considerable expansion of the moderate decay hazard zone in the interior wet belt of British Columbia, across the northern edge of the Prairies and around the Gulf of St. Lawrence. This suggests a greater need for preservative treatment in these parts of Canada.
P I Morris, J Wang


Decay Hazard Classifications in China for Exterior Above-Ground Wood
2007 - IRG/WP 07-20357
A decay hazard map for exterior above-ground wood structures is presented based on Scheffer’s Climate Index, with the major purpose of promoting awareness for proper protection of wood structures in different locations in China. A very large area in the South, including southern Yunnan, most of Sichuan Province and Chongqing, and part of Hunan, Hubei, Anhui, Jiangxi, and Zhejiang, as well as all the more southern areas, has decay hazard ratings above 70, considered a severe decay hazard zone according to the accepted classifications. The moderate decay hazard zone, Index values between 35 and 70, consists mainly of the central areas of China, from the west to the east, including parts of Xizang, Yunnan, Qinghai, Gansu, Shaanxi, Shanxi, Henan, Hubei, Anhui and Jiangsu, as well as Shanghai. It also includes most areas in Northeast China, together with a small pocket around Beijing. By comparison, large areas in the north, from the west to the east, including most areas in Xinjiang, Inner Mongolia, part of Qinghai, Gansu, Ninxia, Shaanxi, Shanxi, and Hebei, and a small part of Henan, are in a low hazard zone with index ratings below 35. The research demonstrates that the areas across China in the Southwest, South, Central China, Southeast, and Northeast, with the highest population densities and also containing areas on the east coast with the strongest economic development, have severe to moderate decay hazard for above-ground wood structures, making proper wood protection more critical and economically important.
J Wang, X Wu, M Jiang, P I Morris


Development of decay hazard maps based on decay prediction models
2016 - IRG/WP 16-20588
Durability plays a very central role in timber engineering, especially when working with wood in use class 3 and above where the risk of decay is high. As one of the primary decay influencing factors, the external condition, i.e. the local climate, is often graded by some type of climate index value. Predominately, climate indices are based on a direct relationship between weather data and decay. The aim of this paper was to develop a new type of climate index, including decay hazard maps, which explicitly considers the material climate. Firstly, the moisture content over time of a horizontal reference specimen was calculated using three different exposure models with weather data (rain, temperature, relative humidity) as input. Secondly, the output from the exposure models was post-processed using two different decay prediction models. Four different exposure model/decay-prediction model combinations were tested in total and repeated for many different locations in Northern Europe. Finally, the relative decay hazard between the different locations was calculated and interpolated, resulting in four preliminary contour plots visualizing the decay hazard in Northern Europe. The maps should be considered preliminary as they have not yet been verified against real decay data. The primary difference between the maps is the range of the relative decay hazard, i.e. the difference between the mildest and the most adverse conditions. The two extremes range between 0.6-2.6 and 0.8-1.8 respectively, which can be compared to the Scheffer index which ranges between 0.8-2.0. The next step, however not included in this article, is to compare the maps against real data.
J Niklewski, E Frühwald Hansson, C Brischke, D Kavurmaci


Evaluation and approval of wood preservatives. Unification of European requirements
1988 - IRG/WP 2310
This paper reviews the current activities within the European Homologation Committee for Wood Preservatives (EHC) towards unification of the requirements on evaluation and approval of wood preservatives in Western European countries.
J Jermer


Studies and experiences of occurrence and development of soft rot in salt-treated poles of pine (Pinus sylvestris) installed in Swedish transmission lines in the years 1940-1945
1977 - IRG/WP 277
The present work describes the result of microscopic examinations of some 2,000 borings extracted from 20 to 23-year-old salt-treated poles (Scots pine) from the southern and central parts of Sweden. The purpose was to map out the occurrence of soft rot in Sweden and its influence on the mechanical strength of the poles as well as to contribute to the development of new and more satisfactory methods for inspection of salt-treated poles. The present work is part of a joint project on soft rot, triggered by alarming results from a series of strength tests carried out by Sydkraft AB (Schmidt and Jacobsson 1976). The following companies and institutions were involved in the project: Sydkraft AB, Svenska Reimpregnerings AB Cobra, the Royal College of Forestry, and the Technical University of Denmark.
H Friis-Hansen


Is Field Test Data from 20 x 20mm Stakes Reliable? Effects of Decay Hazard, Decay Type and Preservative Depletion Hazard
2006 - IRG/WP 06-20327
Effects of decay hazard, decay type and preservative depletion hazard on the performance of variously preservative treated 20 x 20 x 500 mm Radiata pine and Fagus sylvatica test stakes across 13 field test sites in New Zealand and Queensland Australia were determined. Radiata pine treated with an ammoniacal copper quaternary preservative (ACQ) (1.56% m/m a.i.) and copper chrome arsenate (CCA) (0.72% m/m a.i.) was susceptible to sudden failure at some of the sites that had a high brown rot hazard whereas pine treated with copper-azole (CuAz) (0.59% m/m a.i.) was not affected, suggesting that CuAz was particularly effective against brown rots. At the most severe brown rot sites ACQ treated pine was more susceptible than CCA and its performance in service may be compromised as a result, as previously occurred for pine treated with acid copper chromate (ACC). Based on overall performance across all sites pine treated with chlorothalonil plus chlorpyriphos (1.07% m/m a.i.) (11% mean soundness reduction (MSR)), creosote/oil treated pine (37% m/m a.i.) (14% MSR) and CuAz (15%MSR) all gave significantly better protection (5% P) than pine treated with CCA (19% MSR) and ACQ (19% MSR). The decay hazards encountered, as determined by mean soundness reduction after 6.5 years, were more severe than encountered in previous studies at some of the same sites and this was linked to differences of intra-site decay type between test plots and associated decay hazard differences. Greater decay rates encountered in this study were, in part attributed to high preservative depletion. At very wet sites, particularly those likely to have a high soil organic acid content, 20 x 20 x 500 mm stakes are probably too small for accurate interpretation of long-term durability of preservative treated wood. Knowledge of the distribution of different decay types across sites tested, coupled with associated decay hazards and preservative depletion hazard, suggested that 4 test sites of clearly defined features would enable comprehensive field testing of preservative treated wood. Selection of sites is not straightforward and requires a rudimentary knowledge of soil type, geology, vegetation and climate, or comprehensive knowledge of the decay types present. In view of the cost of maintaining test facilities, adequate multi-site testing of new wood preservatives may be achievable through cooperation between research establishments. Possibly, current test site selection criteria fall short of ensuring adequate test site parameters are incorporated and maximum cost effectiveness of testing may not always be achieved through duplication of test site parameters between sites of similar but unrecognised properties. Scope for artificial creation of intra-site decay hazard differences is discussed.
R Wakeling


Performance of softwood preservative treated stakes after 4 years exposure in-ground to decay fungi and termites in tropical Australia
2008 - IRG/WP 08-10643
This field study was based on the 1993 IUFRO method and designed as a graveyard (in-ground) test in the tropical region of the Northern Territory to examine the efficacy of novel preservative formulations developed as alternative protection for softwood timber against decay fungi and termites for Hazard Class 3 and 4. This study was supported by the Forest and Wood Products Research and Development Corporation (FWPRDC). Timber specimens 500 (longitudinal) x 50 (tangential) x 25 (radial) mm were cut from the sapwood of fast grown Pinus radiata D. Don and treated with trimethylborate (TMB), sodium octoborate, linseed oil and fipronil in various solvents (toluene, linseed oil and deionised water) using a vacuum/pressure treatment method. After 4 years in-ground, the solvent control and fipronil (only) treated stakes were slightly attacked by soft rot, brown rot and white rot fungi. Most of the stakes had surface damage only, while few of the solvent controls had severe damage by only decay fungi. There was slight attack on the treated timber by soft rot fungi. A small number of solvent controls and borate treated stakes were severely attacked by subterranean termites, particularly Coptotermes acinaciformis (Froggatt). The fipronil only or fipronil with borate treated stakes were not attacked.
B M Ahmed (Shiday), J R J French, S R Przewloka, P Vinden, J A Hann, P Blackwell


Ensure Durable Wood-Frame Construction under the Climate and Biological Hazards in Shanghai
2009 - IRG/WP 09-20413
This paper provides technical background for developing durability-related provisions for the Shanghai wood-frame construction code. It summarizes the related climate, decay and termite hazards in this area as well as traditional durability solutions used for wood and wood hybrid constructions in China. The overall durability principles or philosophy used throughout this durability chapter are to improve and ensure building durability using integrated protection methods by appropriate design and construction and by using preservative-treated or naturally durable wood where necessary. Of these principles, durability by design is taken as the most fundamental approach for achieving good long-term performance of a building as a whole, and using durable wood where necessary to ensure the durability of individual components. This chapter covers moisture and termite management, and whenever possible multiple lines of defence are provided. Meanwhile, the practical side is also taken into consideration in order to make sure that all measures are buildable on construction sites with a reasonable cost.
Jieying Wang, Chun Ni, Jiahua Zhang


Decay hazard mapping for Europe
2011 - IRG/WP 11-20463
In this study, two different dose-response models for above-ground decay as well as a model transferring macro climate data to wood climate data are presented. The models base on data from field trials, which had been conducted at 28 European test sites, and were used to calculate the relative risk for decay caused by climate variability in Europe. The two dose-response models give coherent results when using either measured wood climate data or simulated climate data. The potential to simulate the relative risk of decay for different sites in the world from climate data has been demonstrated, even if no measured wood climate data is available. A preliminary decay hazard map has been generated to illustrate the climate induced variability within the European continent. For comparative purposes also the Scheffer Climate Index (SCI) had been applied to the same European data base. It was concluded that valuable information for service life prediction of timber structures will be gathered from performance-based decay hazard estimation and mapping.
C Brischke, E Frühwald Hansson, D Kavurmaci, S Thelandersson


Glueline fungicides in veneer based engineered wood products - results from laboratory work for the H1.2 hazard class in New Zealand
2012 - IRG/WP 12-30593
The use of glueline insecticides in plywood and laminated veneer lumber is commonplace in several countries. However, few glueline fungicides are registered for commercial use with previous work suggesting that achieving control of decay from the glueline is very challenging. This paper summarises two tests completed on Pinus radiata plywood with a new glueline fungicide comprising the active ingredients triadimefon and cyproconazole (Triad/Cypro). Tests were completed in New Zealand using a bin method to satisfy the requirements for the H1.2 hazard class (wet area framing). In both tests, Triad/Cypro in the glueline of plywood restricted decay growth comparably or better than the recognised reference preservative of propiconazole plus tebuconazole applied as a light organic solvent preservative treatment.
A Siraa, K Day, P Lobb


System treatments of Pinus sylvestris - influence on moisture, decay and discoloration
2013 - IRG/WP 13-30612
Biological activity can cause challenges for the use of wood in outdoor exposure. Decay and discolouring fungi influence the service life of wooden constructions, and the moisture content of the wood is often an important factor. The aim of this study was to evaluate the performance of different combinations of preservative/modified wood protection treatments and surface treatments for wooden decks in different exposure situations after ten years of field testing. Fourteen different wood protection treatments were tested, in addition to Scots pine sapwood, Scots pine heartwood and European larch heartwood. Furthermore two different surface treatments were included (alkyd oil with iron oxide pigments (AO) and alkyd emulsion without pigments (AE)) in addition to no surface treatment. The test setup used was the “Stapelbädds metoden”. The bottom layer is in soil contact and this stack method provides a moisture gradient within the five layers included. As expected a gradient of increasing wood moisture content and fungal decay rating was found from the top layer to the bottom layer of the stack. For samples with no surface treatment the treatments with lowest wood moisture content was Styren, Tanalith E7, Royal with pigment, European larch heartwood and thermal modification. In the stacks without surface treatment Royal with pigment and Gori SC 100 were the only treatments with decay rating ≤ 1 in all layers, while Scots pine sapwood, Scots pine heartwood and UltraWood all had decay ratings > 2 in all layers. AE surface treatment decreased fungal decay in all layers for furfurylation, Scots pine heartwood and Tanalith M. A similar trend including all layers was not found for AO. All treatments were totally covered by discolouring fungi with the exceptions of ACQ 1900 and Scanimp. Among the untreated samples European larch heartwood generally gave the best performance. The results show that moisture content and fungal decay rate can be reduced with the support of a surface treatment, but they also showed that the opposite can also be the case after ten years of field exposure.
A Schabacker, G Alfredsen, L Ross Gobakken, H Militz, P O Flæte


Glueline fungicides in veneer based engineered wood products – updated results from laboratory work for the H1.2 hazard class in New Zealand
2018 - IRG/WP 18-30726
Results from New Zealand H1.2 ‘bin’ trials containing plywood glueline treated with triadimefon and cyproconazole were reported in 2012 (IRG/WP 12-30593). One of these trials has continued to the present day (2108) and updated results of this trial are reported. The triadimefon and cyproconazole glueline treatment continues to compare with, or outperform, the reference preservative used, being propiconazole and tebuconazole applied as a light organic solvent preservative treatment.
A Siraa, K Day, B Kibby


Observed and projected changes in the climate based decay hazard of timber in the United Kingdom
2020 - IRG/WP 20-20665
The risk of microbiological attack on wood is determined by both material and climatic factors and indeed the hazard for a component is based on its intrinsic durability and the conditions in which it is used. The use of wood and organic materials in construction is increasing but ultimately all these materials will be susceptible to microbiological attack. The Scheffer Climate index applies climatic variables such as temperature and wetting time to assess hazard zones within geographical areas. A changing and variable climate e.g. an increase in heavy but short duration rain events, may have an effect on the incidence or severity of microbiological attack and with the increase in the use of timber this could have significant impact on buildings and construction. This paper shows a significant increase in the Scheffer climate indices for various locations of the UK from 1990 to 2019. The highest index values are seen in the Northern and western areas of the United Kingdom, but increases are seen across the country. The paper also uses representative concentration pathway (RCP) scenarios to project future climate decay indices for the United Kingdom until the end of the 21st century. The projections show a significant increase in the climate decay index even in the lowest RCP scenario, with all regions of the UK moving to index values indicating a very high hazard based on climatic conditions
S F Curling, G A Ormondroyd


Confocal laser scanning microscopy of a novel decay in preservative treated radiata pine in wet acidic soils
1997 - IRG/WP 97-10215
Light microscopy of radiata pine (Pinus radiata D. Don) field test stakes (20x20x500mm3) exposed in wet acidic (pH 3-4) soil for 12 - 24 months showed predominance of an unusual type of decay characte-rised by tunnelling attack of wood cell walls. After two years decay was moderate to severe in wood treated to ground contact CCA specifications and also equivalent retentions of creosote, and a number of new generation preservatives. Relative to other New Zealand temperate test sites and also an Australian tropical site, the New Zealand acidic soil test site was very aggressive. Correlative scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were used to elucidate the micromorphology of this attack. Tunnels of diameter 0.2-5 µm were present throughout all layers of the cell wall, and their orientation was not related to cellulose microfibril orientation. They also showed no preference for particular cell wall layers, indicating a lignin degrading capability. CLSM images showed that living, connecting fungal hyphae were present in the cell lumina and tunnels. This type of attack was predominant in wood that was highly saturated with water whereas wood that was less moist was predominantly attacked by classical white rot. Ongoing isolation and incubation studies in conjunction with further microscopy should enable identification of the fungal species involved.
R N Wakeling, Ying Xiao, A P Singh


Effect of acetylation on decay resistance of wood against brown-rot, white-rot and soft-rot fungi
1989 - IRG/WP 3540
Effect of acetylation on decay resistance of wood was investigated using wood blocks of Cryptomeria japonica, Pinus densiflora, Albizia falcata and Fagus crenata. Blocks were treated with uncatalyzed acetic anhydride for different lengths of time and exposed to Tyromyces palustris, Serpula lacrymans, Coriolus versicolor and unsterilized soil. The action of OH-radical on acetylated wood was also examined using Fenton's reagent. The enhancement of decay resistance by acetylation was revealed clearly for all cases of exposures but varying with fungal and wood species used. For a brown-rot fungus Tyromyces palustris, the weight loss reached almost nil in all woods at 20 WPG (weight percent gain) of acetylation, after the striking decrease from 10 to 15 WPG. For a white-rot fungus Coriolus versicolor, it was counted until 12-15 WPG in the perishable hardwoods used, but not in a softwood Cryptomeria japonica, even at 6 WPG. In cases of another brown-rotter Serpula lacrymans and soil burial, effect of acetylation was intermediate between Tyromyces palustris and Coriolus versicolor. Anti-degradation mechanism by acetylation was discussed, from these weight loss - weight gain relationships, and the IR-and 13C-NMR spectral analyses of fungus-exposed wood.
M Takahashi, Y Imamura, M Tanahashi


Field trial with poles of Scots pine treated with six different creosotes
1996 - IRG/WP 96-30115
In the middle of the 50's field trials with creosote-treated poles were started in France, Germany and Sweden. The trials were initiated by WEI (Western-European Institute for Wood Preservation). Six different creosotes were used and 40 poles per creosote were installed at each test field. Results after 39 years of exposure in Simlangsdalen, Sweden are reported. Poles treated with a heavy creosote were less decayed than poles treated with medium-heavy creosotes. Poles treated with a light creosote were most decayed.
Ö Bergman


Questionnaire - Fungal decay types
1985 - IRG/WP 1265
T Nilsson


JWPA method for testing effectiveness of surface coatings with preservatives against decay fungi
1981 - IRG/WP 2164
In 1979 JWPA established a new method for testing effectiveness of surface coatings in accordance with practical use of preservative-treated lumber. Comparing the new testing method with JIS A 9302, a few new trials - size of wood specimen, weathering procedure, and decay-test procedure - are incorporated.
K Tsunoda


Utilization of curcumin for detection of presence of boron in wood
1982 - IRG/WP 3191
It has been shown that curcumin is not a reliable reagent for detecting boron in wood that has been attacked by fungi
M-L Edlund


Co-operative studies on determining toxic values against wood-destroying Basidiomycetes: Progress report to May 1989
1989 - IRG/WP 2339
This document reports progress on the co-operative study between nine laboratories set up following the proposals contained in Document IRG/WP/2316. Results have been received from two laboratories. Toxic values data have been established successfully using the test fungus Coniophora puteana but problems have been encountered with the other test fungi.
A F Bravery, J K Carey


Monographic cards for wood-destroying fungi. [Fiches monographiques pour les champignons lignivores]
1970 - IRG/WP I 5B
C Jacquiot


On Donkioporia expansa (Desm.) Kotl. & Pouzar
1986 - IRG/WP 1285
Donkioporia expansa is found more often in houses than realised until now. Virulence tests according to EN 113 show not only an attack of oak, but also of other hardwoods and even soft-woods.
G Buchwald


Nondestructive Evaluation of Oriented Strand Board Exposed to Decay Fungi
2002 - IRG/WP 02-20243
Stress wave nondestructive evaluation (NDE) technologies are being used in our laboratory to evaluate the performance properties of engineered wood. These techniques have proven useful in the inspection of timber structures to locate internal voids and decayed or deteriorated areas in large timbers. But no information exists concerning NDE and important properties of wood composites exposed to decay fungi. For our pilot study on several types of wood composites, we examined the relationship between nondestructive stress wave transmission, decay rate and the bending properties of OSB exposed to the brown-rot fungus, Gloeophyllum trabeum (MAD-617). The following measurements were taken: stress wave transmission time (pulse echo test method), static bending test (ASTM D3043-95), and decay (expressed as percent weight). Stress wave measurements correlated with strength loss and with increasing rate of fungal decay. Stress wave NDE has great potential as a method for inspection of wood composite load-bearing (in-service) structures, detection of decay in laboratory tests, assessment of chemical additives to improve wood composite durability, and prediction of long term composite performance.
B Illman, V W Yang, R J Ross, W J Nelson


Moisture content levels and decay of hemlock
1986 - IRG/WP 1287
As a model of decay conditions of wooden members in wooden houses, a decay test was set up in which samples of western hemlock (Tsuga heterophylla) under 4 moisture levels were examined. Each week the samples were weighed and if the weights indicated that their moisture contents were lower than the expected levels, distilled water was added. Every 8 weeks 3 samples from each condition were oven dried at 60°C for 48 hours, up to 48 weeks. After 48 weeks, 3 samples from each condition were oven dried every 16 weeks. The results obtained were as follows: After examining the samples for 96 weeks at 27°C, the mean weight loss of the hemlock samples kept at about 50-100% moisture content level was larger than those of the other levels. If the samples were dried every 8 weeks, the amount of decay in them was not significant. Decay was also not significant in the samples kept at approximately 20-30% moisture content level.
K Suzuki


Dimensional stability and decay resistance of hot-melt self-bonded particleboard by surface benzylated pine chips
1991 - IRG/WP 3652
Akamatsu (Pinus densiflora Sieb. et Zucc: Japanese red pine) particles were pretreated with 40% NaOH solution and benzylated with benzyl chloride, and the surface of particle was converted into meltable materials. Hot-melt self bonded particleboard having smooth and high glossiness surface was prepared by hot pressing at 150°C and 1.96 MPa without using any conventional adhesives. Dimensional stability and decay resistance of the benzylated particleboard were evaluated. Particleboards made of benzylated particles having more than 38% of weight percent gain (WPG) showed that dimensional stability and decay resistance were superior to the conventional particleboard made by using phenolformaldehyde resin as a binder, because hydroxyl groups of wood were substituted by hydrophobic benzyl groups with benzylation. Though bending strength of the board was a little lower than control board due to the damage of benzylated particles during benzylation, its internal bonding strength was very high, because the hot-melting strengthened the inter-particle bonding.
M Kiguchi, K Yamamoto


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