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An evaluation method for less termite attack execution on thermal insulation for fundation walls
2002 - IRG/WP 02-20245
According to the results by the real scale Japanese building tests, the termite installation was observed at very little spaces between foundation and insulation. The termite penetration spaces between foundation and insulation on foundation systems in Japanese wooden houses were checked by the way of streaming speed of colored water. Because of difficulty for its execution, the parts of outside angles and reentrant angles in continuous foundation were more sensitive for the termite penetration. Special accessories of thermal insulation for these angles can be effective for lesser termite installation.
K Suzuki, Y Tanaka


Experimental real building evaluation of termite attack - Effect of the space between the mat foundation and the thermal insulation
2000 - IRG/WP 00-10374
For evaluating the termite resistance of the real house foundation, specially in the case of thermal insulation systems for foundation walls, thermal insulation which can be attacked by termite, must be evaluate. Because of the difficulty of the water penetration of thermal insulation, the water barrier systems can be protected against termite attacks, in our opinions. The observation on the process of the penetration by termites and ones of a traditional barrier system against termites were evaluate by the real building scale test method.
K Suzuki, K Hagio, Y Tanaka


The influence of building design on wood decay
2000 - IRG/WP 00-10339
The cheapest and most effective way to prevent wood decay is to KEEP THE WOOD DRY! You and I know that, but we often forget and attempt a preservative solution to a problem better solved with good design and construction. It's also the answer to a frequently missed exam question in my Architecture class. Just as caulking is a poor substitute for proper design, so preservative treatment should be the last resort in an exposure problem, because, what if the treatment fails? Are we in a position to guarantee that every stick we treat will give "life-of-the structure" performance? "All wood rots in time," and "I won't use treated wood because the incisions are ugly," are just two statements I often hear from designers which indicate the uphill battle we have to get designers and builders to use wood properly. Substituting treatment for better design and then providing ineffective treatment have created a lack of trust of treated products among designers and lack of understanding of wood has prevented the creation of good design fixes. "Why should I pay more for treated wood, it doesn't last any longer than the untreated" a Hawaiian contractor told me; he bought thick slabs of Douglas-fir, treated green with CCA, cut them to length in the field, and placed them directly on the ground as a stairway. He was right; Formosan termites gobbled them up in a matter of months. Wrong material, wrong treatment, wrong application! Other case studies will be presented which illustrate situations where use of treated wood was perhaps not the best solution to exposure problems in structures. Prosecuted for murder for allowing the deck on your rental apartment building to decay?--you will see that one, too. (The following text is a transcription of a lecture presented from slides) I am honored to have been asked to address this meeting of the IRG. I was particularly gratified when asked to present a talk on the general subject covered by my title, which I interpreted as dealing with decay situations where pressure treatment may not be the solution of first choice. As most of you know, preservative treatment is not my field; my field is the diagnosis and evaluation of early stages of decay and the improvement of the performance of wood in structures by proper use and design. I get involved, after the fact, in trying to determine why buildings, or parts of them, have failed. But I am not a designer. I am not in a position to show you drawings which tell you how to do it right, although I'm afraid that is what the organizers really wanted from me. Also, no one asks me out to structures that are performing well; I never get to see the good ones! So, I will start by trying to discuss general principles of design which may control performance of wood in structures, but will move very quickly into performance issues which I know more about. The goal of exterior skin design for wooden buildings can be summarized by adapting a borrowed phrase with the anagram of KIDS--keep it dry, stupid! Dry wood can never decay! With the possible exception of particulate wood products, most building materials intended for exterior exposure perform well enough and are assembled with enough redundancy that how they are put together usually is the most important criterion in their performance. The controlling factors usually are minute details. An example is this roof-wall intersection, where the vertical membrane ran underneath the roof membrane, allowing rain water to gather underneath the roof covering. This, probably, was a result of a simple error in scheduling the building trades--the workers installing the wall membranes came on site before the roofers. All exterior design should be focused on shingling of intersecting materials so that water is constantly being shed outward, away from the structure. In the U.S. the major uses of treated products are in utility poles and railroad ties (sleepers to the Commonwealth). These products are purchased by sophisticated buyers who know what they want, what the treating industry can produce (and even sit with them on the committees which establish the treatment standards), and they get what they want--a long-lived product. In my view, the performance problems are primarily in the consumer area where the typical user knows very little about what they want and how to use it, and can't tell the difference between a good product and a bad one. In this area quality control and certification become important, and I'll talk more about that area toward the end. I do, however, have two examples from the consumer/structural arena where pressure-treated wood is being asked to perform unusual duties and is expected to perform well. It's hard to think of a structure being asked to perform under conditions of greater decay hazard than a houseboat. Here the architect used pressure-treated redwood siding to try to weather the extreme conditions of the Sausalito, California waterfront, and then liked the patina of the Chemonite treatment so much that he had the large structural and decorative members painted to match. This is a quite attractive effect which is, to the best of my knowledge, performing well. A "work in progress" is the restoration of a historic structure, the San Francisco Conservatory of Flowers. This structure is scheduled to be demolished, piece by piece, with all of the thousands of pieces of glass retained and the thousands of pieces of old-growth redwood holding them up replaced with exact duplicates made of young-growth redwood through-treated with Chemonite. I have every confidence that this solution, the only reasonable solution we could come up with for a historic structure, will perform superbly, while maintaining the historic fabric and composition of this unique structure. Now on to the area where I have more experience! I don't know about other regions, but wooden deck failures are becoming increasingly important in the Western U.S. Over the last several decades, our drive for quality outdoor living has converted decks from small, temporary attachments to our homes to large, important portions of the structure, expected to have the same performance life as the rest of the structure. Decks are, by definition, outside the protective building envelope and serve in much more decay-conducive environments than most of the rest of the structure, with the possible exception of the roof which is specifically designed to shed the elements. Decks are not. With decks going higher into the air, their failure increasingly involves human injury. The most absurd of such an instance of which I am aware was a deck in San Francisco on a Victorian structure which was being used as rental apartments. This truly was a tragic incident because failure of the deck killed a woman, but it was made more tragic by an overzealous, headline-seeking, District Attorney who decided to prosecute the owner of this building for murder! Now that would certainly do something for quality control in the treating industry if a product failure could lead to criminal prosecution for murder. But this was not treated wood. Should it have been? This is a three-story, Victorian building in a major, high-class, residential area of San Francisco. With this sort of view, you can see why this is a prized place to live, and why decks are popular. This building used to have a third-floor rear deck, attached to the structure at the U-shaped marking beneath the sliding glass door. From talking to the renter of that apartment I learned that he had invited a wedding party to his apartment for the reception. It was a nice day so most everyone was out on the deck. At one point he gathered everyone together for a group picture. Everyone lined up against the outboard handrail, with a spectacular view in the background, for the group picture. The apartment renter, who was near the sliding glass door with the camera, reported hearing a loud snap and, feeling the back of the deck rising, jumped through the open sliding glass door into the apartment. He looked back in horror to see the deck tip forward, hit the second floor deck and bounce, causing it to rotate 90 degrees and flip upside-down on the concrete covered back yard. A number of the guests received serious injuries when they hit the concrete, but one unfortunate woman, most tragically the new bride, ended up underneath the deck and was killed instantly. The headlines the next day touted the negligence of the building owner for allowing his deck to rot, thereby causing this accident. I was called to the site, a seriously unnerving experience, by the attorneys representing the bride's estate in civil court to document the role of decay in causing the failure. But I could not, making me persona non grata because I disagreed with the conventional wisdom carrying forward the case and was never asked to do anything more on it. Let's look at how I came to my unpopular conclusion that decay was not the cause of this accident. This was a 40 or 45-year-old, untreated Douglas-fir deck, not at all an uncommon situation in the San Francisco Bay Area. Certainly, some decay was present, as expected, and there was evidence that decayed members had been replaced from time to time in the life of the structure. There was a good deal of decay in the outboard ends of the stringers, to which the handrail had been attached. If failure of the handrail had been the cause of the injuries, I would have agreed that decay was a culprit. But it was not--the handrail broke on the way down. At the back edge of the deck, where it attached to the wall, the stringers appeared to butt directly to V-rustic siding while sitting on a 2" ledger, with blocking toe-nailed into the stringers and face-nailed into the siding. Portions of the blocking had been replaced with plywood, apparently as a repair for decayed wood. Also visible in this area are relatively new, as yet unpainted, standard joist hangers. These would have been face-nailed into the blocking and the stringers. Now lets focus on the SECOND floor deck, of similar construction. The stringers rest on a ledger, too, but here the joist hangers have so-called "hurricane tabs" which firmly attach the rear of the deck to the ledger. Looking again at the ledger for the third floor deck, we see that it, too, used to have hurricane tabs, but they were removed sometime since the building was given its current coat of paint. Also notice that the failed deck no longer has these tie-downs. This configuration made the third floor deck very vulnerable to pulling away from the wall, which the second floor deck could not do, unless the ledger itself pulled off the building. The third floor deck was supported by a full-width beam placed a considerable distance back from the handrail edge. Again, looking beneath the SECOND floor deck, we see that it, too, had that construction, but that someone had moved the beam outward, toward the handrail, since the last painting, making it more stable to excessive weight applied at the outboard edge. My reconstruction of the failure was that the heavy load of the wedding party having their picture taken against the handrail caused the handrail edge to bend downward, applying an upward force to the back end of the deck, which no longer was tied to the ledger, causing it to pull the face nails and lift off the ledger. Now unstable and rotating about the single support beam, the deck tilted forward, the rear hitting the second floor deck causing it to bounce and flip over. It probably hit at an angle, causing the 90 degree rotation, because the guests were collected at one corner of the handrail for a better background view. The cause of this tragedy was not the fact that 40-year-old untreated decks have decay in them, it was the result of someone, during a repair, substituting standard joist hangers for the original ones with tie-downs at the deck's connection to the building, and the failure to move the support beam further toward the outboard edge of the deck, as had been done for the second floor deck. I don't like personal injury cases to begin with, and I can tell you I hope I never have another failure case where the pieces are adorned with flowers. But the point I want to make in sharing this with you is that the solution to this problem is NOT the use of pressure-treated wood. Parenthetically, it also is not murder! Another deck problem I have encountered involves a design feature called "mill construction." This involves Douglas-fir 2x6 or 2x8s on edge, nail-laminated together. The architects tell me that this system was developed on the then-timber-rich West Coast of the U.S. during WWII, when the Federal Government had sequestered all construction steel. This approach allowed the construction of long-span industrial floors of wood, without the need for steel to stiffen them. There is no reason to use mill construction today; in fact, because it is so wasteful of wood, there is good reason NOT to use it. It is totally inappropriate in residential construction, where such massive strength is unnecessary, and, because of all the capillary spaces between laminates, should never be placed in exterior exposure. In this case, a deck was created by simply making the laminates in this area about six feet longer. Since there was no roof overhang, the only protection for this assembly was a coating of "miracle goop." These all fail eventually leading to a severe decay problem in this mill construction deck. Because of the capillary spaces, the decay progressed back into the building and down into the glulam beam holding up the downhill side of the building. Again, the solution to this problem is NOT pressure-treated wood. This, simply, is a stupid design which should never be used in residential construction, especially in exterior exposure. Now, here's a deck that's a challenge! We've got a lot of steep, very valuable, land overlooking the Pacific Ocean in California, which tempts people to do things like this. Does anyone want to take on responsibility for the treatment of the wood holding up that deck, especially in light of the criminal prosecution in San Francisco? Which brings up the issue of quality control for treated wood entering the consumer market. These data are old, now, but they were produced from a sampling of retail-end lumber which contained a brand by a third-party agency guaranteeing that this lumber met their specifications. Unfortunately, commercial politics destroyed even this agency in the U.S., so there is no organized, even partially reliable, third-party inspection quality assurance available to retail consumers in the U.S. We can not expect builders to rely on treated products if we can't even meet our own minimum standards a majority, let alone approaching 100%, of the time. This is a foundation piling, driven into muck soil to support a structure. The non-green patches are where bark was still present during treating and has sloughed off after drying in place, leaving untreated wood. Even where it is green, the penetration was less than 1/8-inch. The tragedy here is that there are actually over 400 such piles, holding up an 80-unit condominium structure, with no way to replace them. The solution to this problem would have been properly pressure-treated pilings, but, without quality control, that didn't happen. Here is a stack of 6x14, Douglas-fir beams, treated with Chemonite. This shows a pretty good representation of the difficulty of treating sawn Douglas-fir. The problem here is not the quality of treatment (that's actually pretty good for sawn Douglas-fir), the problem is that the designer ordered the beams in the wrong length, requiring that they all be cut to length in the field, exposing the untreated wood you expect at the center. Here, treated wood was the recognized solution, but the end-user messed it up. The developer of this project in Kailua, on Oahu, told me at a seminar in the early eighties that there was no point in paying extra for treated wood because it didn't last any longer than untreated wood. Granted, at that time Hawaii was treating green, sawn Douglas-fir with CCA and calling it "treated" under a "Hawaii use only&quot u32 ?stamp. Still, I jumped at his invitation to see his experience, and this is what I found. The roof of the garages was sodded--a challenge for wood anywhere, but particularly in Formosan termite country. And for the stairways, he was using 3 or 4-inch-thick slabs of sawn Douglas-fir, cut to length in the field, and placed directly on the ground. He was already replacing rotten and termite-eaten treads less than two years into their service life. Maybe you could get away with this with adequately treated wood, but why try? And you certainly won't be successful when the treated wood you're using has penetration like this! Glulams in exterior exposure present a special problem. Most made-up members are too large to treat and, with woods like Douglas-fir where penetration only to the depth of the incisions can be expected, this is clearly not a solution. Treating the laminates also is problematic, not just because of possible effects on gluing, but, in California, the shavings were declared by the State regulators to be a Class I toxic waste. The laminators got rid of their treated wood in a hurry! This project used glulam for nearly everything on the outside of the buildings--through-members protruded beyond the building envelope, blocking and rim-joists were glulam with the sides exposed, they even designed glulam "stubs" to make it look like the beams crossed over the columns. The solution to this problem is NOT pressure treatment. This, again, is simply a matter of stupid design! In fact, because of their innate nature, glulams simply are not members that should be in exterior exposure. Examination of this end, with the various grain orientations of the different laminates, shows that, if this beam were to undergo any significant moisture content cycling, it would develop up-facing checks deep down into the beam, directing water into the center of the member where it becomes trapped and facilitates internal decay. These are solid wood "flying" beams, penetrating the walls on both sides and impossible to flash or caulk successfully because of all of the potential for movement, therefore decaying and leading the decay into each structure. Pressure treatment is not the solution to this problem, this is simply another dumb use of wood. I'm not sure that our fire codes allow this anymore, anyway. I have heard it said by a number of architects that, usually, caulking is simply a dsigner's poor excuse for proper design. Even if it doesn't leak, it creates a lasting, constant maintenance problem for the building maintainer. These examples led to wood decay, but, again, treatment was not the solution. No amount of treatment could overcome the problems caused by this misapplication of grooved plywood siding and scarf-jointed battens. Grooved plywood should never be applied with the grooves horizontal, because it causes up-facing cracks into the center of the panel at the edge of each groove and the groove acts like a gutter directing water to the joint between panels. A properly assembled scarf joint sheds water back to the surface of the two joined pieces, while these reverse scarfs draw water in to the exact location the battens were put on to protect. This is the only case I've ever seen of mushrooms growing directly out of building siding, but treatment would not have helped this either. The siding leaked water into a wall filled with insulation which was, essentially, crushed newspaper, which provided both the moisture and carbon source to support extensive decay. Playground equipment! I've lost track of the number of calls I've gotten from parents asking for a "non-toxic" preservative for the playground equipment their children play on. No matter how you start trying to answer that question, you lose them quickly. This is the equipment my kids played on and I always took the position that I would rather risk their eating a little chemical than running the risk of having one of these huge members decay and come down on their head. Here treatment should be the solution but, because of chemophobic parents, it will only be a workable solution if we can develop deep penetration with that elusive "non-toxic" preservative. Actually, that is what happened with this playground equipment (unfortunately, the "come down on their head" part). The parents club got a number of old 12x12s--former excavation shoring, which had been stored solid-piled on the ground for a number of years. They buried one end in the ground, creating a Stonehenge-like circle of uprights. They fastened eye-bolts to the top of these, now, vertical cantilever members, attached chains which were threaded through old tires, producing a creative, undulating, play surface. Alertness during the construction process would have revealed that these members were badly decayed, as the stack of washers penetrating into the member in an attempt to tighten the nut against a firm surface, showed. Unfortunately, this was another personal injury case. This timber broke at the ground line, hitting a little boy in the head, killing him. This case is just a series of mistakes by well-meaing, but uninformed, people, for which treatment, again, would not have been the solution. But the school's solution--replacing the wooden equipment with steel--also is ill-advised. If my kids were to fall from a piece of playground equipment, I'd much rather they hit their head on wood than a steel 6x6. Wooden roofs should always have a pitch to them, for natural, passive, drainage. All that's needed here is a single pinhole through the roofing material and this roof is a goner. I guess you could get away with this by using adequately treated wood for everything below the water, but why bother? Change the design! Finally, on the West Coast of the U.S., we are building with green lumber which, in many cases, already is infected with decay fungi--the same ones responsible for most above-ground decay. Since most ordinary decay fungi go dormant between wettings, we are building our buildings with the fungi which will decay them already provided. All that's needed is water. The solution to this problem is not treatment, it's kiln-drying. Although I've shown you a number of examples of inadequate wood performance in structures for which I've suggested that preservative treatment would not be the appropriate solution, there are a number of things we should do, I believe, to position preservative treatment in a way to make it available as a solution if other methods prove unsuccessful. Some challenges to preservative research which I recognize would include the following. We need to improve penetration, especially in refractory species like Douglas-fir. Adequate drying prior to treatment, even in large members would help. New approaches, such as vapor metal and cold plasma treatments may hold promise for their ability to increase penetration. We need to find a substitute for visible incisions and, at the same time, achieve deeper incising. I have frequently heard from architects, "I won't use treated wood because those little knife marks are ugly." We need to improve quality control; is the ability to guarantee treatment that meets certain specifications in 100% of pieces treated really not attainable? In our emerging global economy, perhaps quality assurance needs to be taken on by one, or more, international organizations, as in the ISO9002 systems for other commodities. Finally, is it completely impossible to give those parents a "non-toxic" treatment for their playground equipment? The solutions to these issues will require cooperation. Going it alone is an outmoded concept, which, in this era of secrecy and non-cooperation in academia, probably means that the treating industry is going to have to get together and do these things, if they are going to get done. I do, however, have the answer for one of the oldest philosophical questions about being alone. Alan asked me to be a little outrageous and present things that would cause attendees to talk about them in the halls the rest of the week. I think I've done that, Alan. If I went a little overboard, I apologize.
W W Wilcox


Generic code of good practices for wood protection facilities. Part 1: Wood protection (antisapstain) facilities
1993 - IRG/WP 93-50003
In general, the potential of high toxicity (aquatic and human) of wood protection (antisapstain) chemicals dictates the need to protect the environment and humans from its harmful effects. This document is a compendium of recommendations for the design and operating practices of wood protection facilities. The suggested recommendations focus on achieving the objectives of protecting the environment and workers in a wood protection facility from harmful exposure to wood protection chemicals.
G Das, V N P Mathur


Development on Damage Functions of Wood Decay for Building Envelope Design
2005 - IRG/WP 05-10556
For the hygrothermal analyses of building envelope systems for insulation design, we tried a natural decay test of wetted wood specimens without any inoculation of fungi. Three principal experimental types: under steady-state conditions (Experiment A), at a cyclic water dripping under Non-steady conditions (Experiment B) and at a cyclic water dipping under-steady conditions (Experiment C), were carried out for this purpose. After these tests, each specimen was determined its longitudinal compression strength. The detection of decay was checked this standard strength value by species according to Japanese building code and its corrected value by these moisture contents. As the results of the Experiment A, some fungal growth was observed within 10 weeks at the moisture contents of levels between 30wt% and 70wt%. As the results of the Experiment B, the simulated condition of short time condensation in summer was observed fungal growth but not affected decay problems within 124 weeks. As the results of the Experiment C, the simulated condition of periodical wetting as under floor or bottom of cladding was not observed any decay.
H Suzuki, Y Kitadani, K Suzuki, A Iwamae, H Nagai


Canadian code of good practices - Recommendations for design and operation of wood preservation facilities
1990 - IRG/WP 3582
The rationale and procedures for the development of a set of recommendations for design and operation of wood preservation facilities in Canada are discussed. Multi stake holders involvement in problem identification, problem assessment, state of the art knowledge database, implementation and periodic assessment procedures are important considerations for the successful development of a Code of Good Practices for wood preservation facilities.
V N P Mathur, G Das


Results of survey conducted at Orlando to solicit attendee feedback on program design
1994 - IRG/WP 94-60026
J N R Ruddick


Determination of physical properties of wood by Novel Guide
2006 - IRG/WP 06-40345
In empirical and theoretical determination of physical properties of wood, a schematic guide has been developed (as a novel guide) for the purpose of bringing facilities to researchers with a processing quantity in terms of data compilation. In this article physical properties of wood have been briefly described in respect to their effect on impregnation process, and technical information has been provided on usage of novel guide.
I Usta, M D Hale


Flow charts for termite and decay tests to determine the natural durability of Japanese cedar (Cryptomeria japonica D. Don)
2008 - IRG/WP 08-20385
This paper deals with the experimental flow charts that were used for determination the effects of fungal decay and termite attack on Sugi heartwood during the course of the study of “Comparative studies of natural durability of Japanese cedar (Cryptomeria japonica D. Don) among the geographic cultivate”, which was carried out by Usta et al (2006).
I Usta, S Doi


Premature failure of treated timber in wharfs in Papua New Guinea, attributed to defects in design
1991 - IRG/WP 4158
The performance of timber in wharfs in Papua New Guinea has been monitored for a number of years. Premature failure of wharf structures was found in many cases to be due to defects in design rather than ineffective preservative treatment. Above-water timbers were found to be prone to severe checking followed by decay. Protection for the end grain of pile tops and the limiting of radial checking in them was found to be vital. Removable metal caps and stout metal bands sized to give a snug fit around the circumference of the pile were found to give the best protection. Major areas of decay or marine borer attack were most common where other structures were attached to the piles in such a fashion that the "envelope" of treated sapwood was breached. In order for treated timber to perform satisfactorily in wharfs, care has to be taken at the design stage. Any post-treatment machining should be undertaken with suitable tools and remedial treatment or protective measures will be required. A list of recommendations for the use of treated timber in wharfs in the tropics is given, relating to the preparation of wood, the construction of the wharf and the protection of vulnerable parts of the installed wharf. The question of good and bad design, and its effect on service life of wharf timbers requires further investigation. The author requests colleagues with information relating to this to contact him.
S M Cragg


Design of Field Trials for Evaluation of Antisapstain Products
2003 - IRG/WP 03-20263
Field trialing is an important phase of antisapstain product development and careful planning is required to ensure trial validity for predicting performance in the industrial situation. Experiences of trialing antisapstain products on lumber over a ten-year period are discussed in this paper. It is not mandatory to source "fresh " wood for trialing and useful information can be generated even if the wood shows visible signs of pre-infection. Measurement of uptake of preservative working solution is recommended, as uptakes can differ considerably between preservatives. Also, continuing wood drying after sawing can cause treatment uptakes to progressively increase over the trial duration. Strong moisture gradients develop in treated packets during storage and the moisture profile is a particularly important determinant of the development of the various fungal infections. The period and method of assessment should be appropriate to demonstrate differences between products that would be reflected in sawmill practice.
F W Frazer, N R Edmonds, B J Nairn


Field test design for service life prediction of wooden components
2005 - IRG/WP 05-20308
Wood is predominantly degraded by organisms. Thus, compared to other building materials, service life of wooden material is influenced by many more factors, which are divided into direct and indirect factors. Climate, geographical position, and construction criteria count to the indirect decay factors. Besides material inherent properties (natural durability, wood preservatives), wood temperature, wood moisture content, and the presence of certain species of wood degrading organisms are the strongest direct factors influencing service life of wooden building components. On this account an experimental set up was developed to quantify these direct decay factors: Field tests were performed in European Hazard Class 3 (EHC 3) to determine the influence of macro and micro climate on decay progress and decay factors such as temperature and moisture content of wood. Therefore Scots pine sapwood (Pinus sylvestris L.) and Douglas fir heartwood (Pseudotsuga menziesii Franco) have been positioned in double layer test devices since 2000. Thirty-two sites in Europe and the United States representing preferably different climatic conditions were chosen for exposure of the test devices. For all sites, data on climate were available since they were located next to an official meteorological station. This way all relevant climatic factors (precipitation, air temperature, relative humidity, sunshine duration, wind) are correlated with MC and temperature of the samples to be measured once a minute and logged once a day. Furthermore the samples were evaluated respecting to decay and discolouration every year according to EN 252 (1990). Preliminary results concerning the influence of macro and micro-climate show that this approach will provide a sufficient data base for a better understanding of the most important factors determining decay.
A O Rapp, C Brischke


Recent development in North American industrial wood preservation plants
1988 - IRG/WP 3467
After remaining static for many years there have been a number of changes in plant design and treating cycles in recent years. This has been particularly true in the USA where few restrictions are placed on plant treating cycles by specifications; since only results type specifications are used. It is also important to realize that the AWPA Specifications for Southern Yellow Pine only call for treatment of the sapwood since the heartwood has a high natural resistance to termites and decay. This is evidenced by old plantation houses on Southern and West Indian sugar Plantation houses that have stood for several hundred years. This paper attempts to set out these changes and the reasons for them. Industry often appears to have jumped ahead of research or the results of research have not filtered down to the industry and these knowledge gaps are mentioned in the appropriate sections. These sections try to separate the many inter-related factors into simple headings covering plant components and other factors influencing treatment. Some of the criteria presented in this paper have only been recently recognized as of importance so that results from past research is often found to be inconclusive when studied under the light of present day knowledge (e.g. rate of pressure rise was not noted).
J F Bridges


Design of a laboratory method for evaluating the effectiveness of soft rot preservatives
1988 - IRG/WP 2312
This purpose of this work was to design a method which makes it possible to evaluate the effectiveness of products which present protect wood against soft rot, using new products·of a different nature, on wood of·Pinus sylvestris L. and Fagus sylvatica L., and which, suitably applied, avoid big economic losses deriving from lack of knowledge of the active principles suitable to present protect wood intended to be in contact with the ground or for use in construction.
M T De Troya, A M Navarrete


A real scale evaluation method and results on termite resistance of housing wall systems and floor framings
1999 - IRG/WP 99-10314
For evaluating the termite resistance of real scale houses especially housing wall systems and floor framings, a experimental building was prepared. After initial feeding of termite, this house was constructed. In this experimental building, several parts which were built by different wall systems and floor framing. The room temperature of these parts were controlled. Water can be provided in the wall systems. Well termite installed feed log was inserted in each wall system. After 2 weeks, the difference of agregation can be observed. By this experimental building, the termite resistance of housing system can be classified.
K Suzuki, K Okada, K Hagio, Y Tanaka


Three-year field trials of polymeric formulations which provide a new basis for the invention and design of non-toxic wide-spectrum wood preservatives
1994 - IRG/WP 94-40029
Three types of non-toxic polymeric formulations invented using a new approach to wood preservation were challenged with termites and fungi in three-year ground-contact field trials in the sub-tropical climate of Natal. These formulations were copper soaps of carboxylic acid groups of unsaturated fatty acids of waxes and edible vegetable oils; of resin acids of rosin, and, of synthetic unsaturated polyester resins. The formulations self-polymerise within lumena of wood elements after pressure-impregnation and also co-react with carbon-carbon double bonds and aromatic nuclei of lignin. The biocidal mechanism is based on the release of copper by hydrolysis under humid conditions and on the reformation of the same bond on redrying of the treated timber in service. All formulations tested were effective and durable. Rosin formulations at retentions of 0.91 kg/m³ and polyester formulations at retentions as low as 0.4 kg/m³ each out-performed creosote at 37.5 kg/m³.
A A W Baecker, A Pizzi


Minimisation of the Environmental Impacts of Coatings on Exterior Wood by Optimisation of their Life Spans
2003 - IRG/WP 03-50197
The study has shown that the environmental impacts from coatings on exterior wood are dependent criteria on their life spans. A minimisation of the environmental impacts can be performed with the help of the integrated design model, which is tested in this study. The optimal life spans, found as reference service lives from the exposure tests, statistical evaluation and the assessment of experts were used for forecasting in Life Cycle Assessment of the coatings on exterior wood. The integrated life cycle design, performed in this study, showed that the water-borne acrylic coating and the water-borne acrylic stain are the best choice as regards the integrated assessment of the environmental impacts and service lives of the coatings. The discussed coating systems are a solvent-borne alkyd coating, a water-borne acrylic coating, a water-borne acrylic stain, a solvent-borne alkyd stain and an alkyd oil.
L Strömberg


The Development of a novel method to preserve reeds using an environmentally friendly timber preservative and a unique engineering design.
2006 - IRG/WP 06-40335
Reeds are used in the construction of bush lodges in Northern Kwa- Zulu Natal, South Africa. Fungal, insect and ultra-violet damage to these reeds is posing a severe problem. Within a space of two years, the reeds are attacked and have to be subsequently replaced; a time consuming and costly exercise. A novel method has been used to successfully preserve these reeds with an environmentally friendly preservative containing disodium octaborate tetrahydrate in a water-based polymer system. The polymer allows for uninhibited diffusion of boron into the reeds, whilst the polymer cures to form a continuous protective film. By making use of two strategically drilled holes, which are 2 mm in diameter, the preservative is introduced into the reed shafts and nodes. The boron successfully diffuses into the walls of the reeds and is prevented from leaching out of the reeds. The water-based polymer provides sufficient protection against excessive ultra-violet damage. The test site, which is situated in the Hluhluwe Game Reserve in Northern Kwa-Zulu Natal – South Africa, has been monitored for nearly two years and there are no sign of insect or fungal damage to the reeds. Over the two-year period, the reeds were periodically inspected for deterioration in colour and deterioration in structural integrity.
K Govender, K G Moodley


Criteria for environmentally and socially sound and sustainable wood preservation industry
2006 - IRG/WP 06-50237
This paper is dealing with critical criteria for environmentally and socially sound and sustainable wood preservation industry. A research study supported by past experience, knowledge and training on relevant topics and consultation of relevant appraisal manual, training module and technical guideline revealed concise widespread checklists for sustainable establishment of wood preservation industry. Through this paper safe and sound site selection, safe land acquisition and involuntary resettlement, sound regulatory aspects, safe planning and information, safe design and construction, safe operation, appropriate environmental management plan (EMP) and environmental impact assessment (EIA) of wood preservation industry have been ensured. The relevant industrialists can easily follow the checklists during establishment or renovation of wood preservation industry.
A K Lahiry, M Hasan, M A J H Chowdhury


Building with termites: The challenge of biomimetic design for carbon neutral buildings.
2009 - IRG/WP 09-20405
The main aim of this paper is to present humanity and termites as design partners in the creation of a new dimension of ecosystem understanding. “Beyond biomimicry: What termites can tell us about realizing the living building”, Turner and Soar (2008) opens up a new era in how we think of human habitations, not only on earth, but maybe on other planets, and using the termite model as the corner stone of innovative engineering. We know that termites are masters of constructing ‘buildings’ that meet all nutrition, energy, waste disposal needs, shelter, and food sources for many other animals and insects. We need to emulate the symbiotic abilities of termites to survive over time, for as Margulis (1998) pointed out, we all live on this symbiotic planet, and symbiosis is natural and common. The challenge to architects, builders and the wood protection industry will be immense, but none the less intellectually and practically stimulating, particularly with climate change implications. Also, briefly discussed is the need to amend Australian Standards and Building Code of Australia “deemed-to-satisfy” legislation. So, we can mimic termite design and management systems in our bid to manage and sustain energy efficient buildings.
J R J French, B M Ahmed (Shiday)


Service life prediction of wooden components – Part 2: Impact of material, exposure and design details
2010 - IRG/WP 10-20440
Dose-response functions permit to estimate the moisture and temperature induced decay potential for any wooden building component and exposure, and thus the service life to be expected. In part 1 of this series dose-response functions were established as a result of double layer field trials carried out at 24 European test sites over up to eight years. Using them makes it no longer necessary to conduct field trials as long as decay actually occurs. They allow determining dose-time functions for a certain construction detail over shortened time periods (2 3 years). Within this paper we present the test set up of different studies aiming on quantifying the impact of material, exposure and design details on the service life to be expected for wooden components. Therefore long-term moisture recordings were applied to different wooden commodities, e. g. fence posts, pickets, decking, and facades. Furthermore, the impact of orientation, distance to the ground, and driving rain load on facade panels was studied. Finally dose-time functions will be recorded for ten different wood species used in horizontal and vertical orientation. First results from the various studies including preliminary service life estimation for various components are also presented.
C Brischke, B Lauenstein, M Bilstein, T Bornemann, A O Rapp


Optimization of oxalic acid production for bioleaching of metal components from CCA-treated wood by an unknown Polyporales sp. KUC8959
2010 - IRG/WP 10-50266
A brown-rot fungus, an unknown Polyporales sp. KUC8959, has recently been identified and proven as a prominent fungal species for bioremediation of CCA-treated wood wastes in our Lab. The fungus produced a larger amount of oxalic acid than other fungi tested, and removed 90 % or more of chromium, copper and arsenic from CCA-treated wood sawdust through bioleaching process. The bioleaching process was consisted of two steps comprising fermentation of the fungus for oxalic acid production and then extraction of metals by oxalic acid produced by the fungus. In order to maximize bioleaching efficiency, optimal fermentation conditions for oxalic acid production by the fungus is required. The objective of this study was to optimize oxalic acid production by unknown Polyporales sp. KUC8959. We used a 20-run central composite design (CCD) using response surface methodology (RSM) with three variables, that is, nutrient concentration, fungal biomass, and fermentation period. From the pre-cultured liquid fermentation broth, fungal hyphae were removed by filtering and then washed thoroughly with sterile deionized water. In accordance with the experimental design, fungal biomass (6.99, 18.32, 34.93, 51.55, or 62.88 mg) was inoculated in a flask containing 100 mL of malt extract solution (0.5, 1.11, 2, 2.89, or 3.5 %). Thereafter, the flask was agitated at 150 rpm on a rotary shaker at 27 °C for 48, 96.66, 168, 239.34, or 288 hours. From the fermentation broth, the amount of oxalic acid produced was determined by high performance liquid chromatography. The fitted RSM model investigated showed high regression coefficient between the variables and the response (R2=0.960) indicating that the model can be highly accurate in predicting the oxalic acid production at various conditions. The model suggested that optimum nutrient concentration, fungal biomass, and fermentation period were 2.40 %, 47.84 mg and 228.96 hours, respectively, to produce 4.11 g/L of oxalic acid. This fitted model will further be used for bioleaching of metals from CCA-treated wood.
Yong-Seok Choi, Min-Ji Kim, Jae-Jin Kim, Gyu-Hyeok Kim


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


Quantitative design guideline for wood outdoors above ground applications
2011 - IRG/WP 11-20465
This paper describes the background and principles behind an engineering design guideline for wood in outdoor above ground applications, i.e. use class 3 according to EN 335. The guideline has been developed in the European research project WoodExter and can be seen as a first prototype for a quantitative design tool in the area of wood durability. It is based on a defined limit state for onset of decay under a reference service life of 30 years. Onset of decay is defined as a state of fungal attack according to rating 1 in EN 252. The approach is to determine the climate exposure as a function of geographical location, local exposure conditions, sheltering, ground distance and detail solution. The exposure is then compared with the material resistance defined in five classes and the design output is either OK or NOT OK. The present version of the guideline covers applications for decking and cladding. The data included in the guideline have partly been estimated with the help of a dose-response model for decay, which was used here to derive relative measures of decay risk between different locations and between different detail solutions. Some other elements have however been estimated in a semi-subjective manner based on expert opinions as well as experience from field testing. The guideline has been verified by a number of reality checks, which show that the output from the tool agrees reasonably well with documented experience. The guideline has also been presented in a computerized Excel format, which makes practical use convenient. It is believed that many building professionals will appreciate a tool within the area of wood durability which has an approach similar to other design tasks in building projects. An advantage is that in applying the method the designer will go through a check list where he/she becomes aware of the importance of appropriate detailing solutions. In addition the user will have to think about the target service life as well as the consequences of non-performance in the design of a construction.
S Thelandersson, T Isaksson, E Suttie, E Frühwald, T Toratti, G Grüll, H Viitanen, J Jermer


Design, synthesis, characterisation and effectiveness of ‘Locked-in-Boron’ chemicals for H3.2 level of wood protection
2011 - IRG/WP 11-30577
Boratrane molecules with five-membered and six-membered molecular ring systems, and with various ring substituents were synthesised, characterised and formulated for wood treatment for accelerated laboratory bioassays using wood decay fungi as test organisms. Six-membered ring boratranes showed lower efficacy in laboratory assays than five-membered ring boratranes. One alkyl-substituted boratrane with a five-membered ring molecular structure was used in a 10-year natural hazard exposure test using lap-joint specimens treated with three boratrane concentrations. The half-life for boric acid controlled release for wood treated with the boratrane at a nominal 0.1% boric acid equivalent (bae) was approximately 4 years, while that for a nominal 1% bae was approximately 7 years, compared with a half-life of 10 months for conventional boric acid/borate wood treatment.
R Franich, H Kroese, S Gallagher, S Hill, B Kelly, G Billett, R Meder, W Rae


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