To adequately describe the current state of Wood Protection requires an approach that involves viewpoints from various regions of the world, and within some of those regions, a country by country approach. In this regard, we have included the following regions, Africa, Asia, Europe, North America, Latin America, and Oceania. These regions are subdivided as content permits.
In order to avoid using complex or colloquial terms throughout this document go to the Acronyms webpage which provides explanations of the abbreviations used.
There are 4 industry groups related to wood protection; Japan Wood Protection Association, Japan Wood Preservers Industry Association, The Japan Termite Control Association, and Japan Wood Preservatives Industry Association.
There are 2 national standards related to wood protection, JIS and JAS..
In the current JIS, 2 major are JIS K 1570 “Wood preservatives” and JIS K 1571 “Wood preservatives - Performance requirements and their test methods for determining effectiveness”. Both of JIS are of important for the certification of wood preservatives and treated wood products.
Present preservatives for pressure treatment specified in JIS K 1570 (2010) are ACQ-1, ACQ-2 (Ammoniacal Copper Quaternary), CUAZ (Copper azole compound), AAC-1, AAC-2 （Quaternary ammonium compound), BAAC (Boron, quaternary ammonium compound), SAAC (Quaternary ammonium non-ester pyrethroid compound), AZAAC (Azole quaternary ammonium non-ester pyrethroid compound), AZNA (Azole-quaternary ammonium neonicotinoid compound) as water borne preservatives, and NCU-E, NZN-E, VZN-E (Fatty acid metal salt compound), NCU-O, NZN-O (naphthenic acid metal salt compound), AZN(Azole-neonicotinoid compound), A (Creosote oil) as oil-type preservatives. JIS K 1571 is of importance to specify the performance requirements of preservatives and test methods for determining effectiveness. Beside them, there are JIS A 9002 “Preservative treatments of wood products by pressure processes” and JIS A 9104” Wood crossties treated with preservatives by pressure processes -Specification-”.
In the "JAS system" based on the JAS Law, JAS marks can be put on agricultural, forestry and fishery products conforming to the JAS established by Ministry of Agriculture, Forestry and Fisheries (MAFF). Producers and manufacturers can propose standards related to their business to MAFF in the system. The JAS are to be reviewed within five years after their enactment or previous review in order to meet the changing needs of society. JAS for wood products are for glued laminated timber, sawn lumber, laminated veneer lumber, plywood, structural lumber for wood-frame construction(2×4), log, flooring, structural panel, cross laminated timber, and former 5 products have regulations about preservative treatment right now.
Certification system of products related to wood protection is complicated. To simplify it to 3 steps. The first step is to register the wood preservative with safety data of active ingredients and formulation data, efficacy data, instruction of use, and waste management to Japan Wood Protection Association (JWPA). There are almost 300 certified products by JWPA. The second step after JWPA certification is to register the treated product to Approved Quality （AQ）by Japan Housing and Wood Technology Center (HOWTEC). AQ registration requires that preservative should be registered in JWPA certification, and data of on-site tests in the plant to confirm constant quality of up-take, penetration, retention of treated product. There are almost 300 certified treated products by HOWTEC. The third step after AQ is to incorporate the type of wood preservative used in AQ product into the description of JAS, and then to apply and obtain the JAS registration through registered certified bodies, Japan Plywood Inspection Corporation, Japan Lumber Inspection & Research, Hokkaido Lumber Inspection Corporation by undergoing examination of quality control and facility, and on site inspection of factory.
Many government policies regarding the promotion of wood utilization have been proceeded in recent years. Most important act will be “The Act for Promotion of Use of Wood in Public Buildings（2010）” by the Minister of Agriculture, Forestry and Fisheries, and the Minister of Land, Infrastructure, Transport and Tourism. Also, the policy that reforms to turn forestry and forest products industries into a growth sector includes the promotion of wood use in mid-to-high-rise buildings and non-housing buildings by Forestry Agency (2018).
When wood is used for especially the facade of buildings, preservative treatment is required to enhance durability in outdoor exposure conditions. In addition to conventional preservative treatment, there are several new treatment methods developed in the followings. One is a solvent recovery treatment system using preservatives; cyproconazole + imidacloprid solved in non-combustible organic solvent with solvent recovery (vacuum+ high-frequency heating), that enables the good dimension stability of timber. The second is an oil-borne preservatives treatment with pressure spray and post penetration treatment in organic solvent (non-polar, mix of low & middle boiling point) using preservatives; cyproconazole + bifenthrin or cyproconazole + etofenprox that also realizes the good dimension stability. Durable timber without preservatives such as thermal modification, chemical modification, and resin treatment has become popular. In addition, demand of fireproof wood is increased now.
By Koichi Yamamoto: Japan Wood Protection Association, Fellow of Forestry and Forest Products Research Institute.
The Biocidal Products Regulation (BPR, Regulation (EU) 528/2012) concerns the placing on the market and use of biocidal products, which are used to protect humans, animals, materials or articles against harmful organisms like pests or bacteria, by the action of the active substances contained in the biocidal product. This regulation aims to improve the functioning of the biocidal products market in the EU, while ensuring a high level of protection for humans and the environment. The text was adopted on 22 May 2012 and was applicable from 1 September 2013. It repealed the Biocidal Products Directive (Directive 98/8/EC).
All biocidal products in Europe require an authorisation before they can be placed on the market, and the active substances contained in that biocidal product must be previously approved. There are, however, certain exceptions to this principle. For example, biocidal products containing active substances in the Review Programme can be made available on the market and used (subject to national laws) pending the final decision on the approval of the active substance (and up to 3 years after). Products containing new active substances that are still under assessment may also be allowed on the market where a provisional authorisation is granted. The BPR aims to harmonise the market at Union level; simplify the approval of active substances and authorisation of biocidal products; and introduce timelines for Member State evaluations, opinion-forming and decision-making. It also promotes the reduction of animal testing by introducing mandatory data sharing obligations and encouraging the use of alternative testing methods.
The approval of active substances takes place at Union level and the subsequent authorisation of the biocidal products at Member State level. This authorisation can be extended to other Member States by mutual recognition. However, the new regulation also provides applicants with the possibility of a new type of authorisation at Union level. A dedicated IT platform, the Register for Biocidal Products (R4BP 3), is used for submitting applications, exchanging data and information between the applicant, ECHA, Member State competent authorities and the European Commission. Another IT tool, IUCLID, is used for preparing the applications. For more information click here.
Almost 70% of Sweden is covered by forests and the forest products industry plays a major role in Sweden. Sweden is the 5th largest exporting country in the world with respect to pulp, paper and sawn goods.
Major wood species are Norway spruce (Picea abies), 40 %, and Scots pine (Pinus sylvestris) or Baltic redwood, 39 %, as it is called as well, birch (Betula pubescens, B verrucosa), 13 % and other species, 8 %. Scots pine is historically the most important species with respect to industrial wood preservation but since the early 1990s also considerable amounts of Norway spruce is treated, mainly for the export market.
Decay is the major cause of biodegradation in Sweden, although the house longhorn beetle (Hylotrupes bajulus) causes some damage to buildings in southern and eastern parts of the country.
The Swedish wood preserving industry is one of the biggest in Europe with an annual production of about 1.5 million cubic metres. Roughly 10 % of the total sawmill production in Sweden is preservative-treated.
Focus of the production is on sawn timber for the residential sector, whereas other commodities, such as poles, railway sleepers and window joinery (millwork) play a minor role. No official regulations or building codes require the use of wood treated with wood preservatives.
Since the phase out of CCA in the mid-90s copper-organic wood preservatives, such as copper-quat, copper-azole and copper-HDO have replaced the CCAs. LOSPs containing azoles are used for the treatment of a minor part of window joinery by double vacuum. The major part is treated with a superficial application of a water-borne product (flow-coat), containing IPBC and azoles. Creosote is still used for poles and railway sleepers.
Wood preservatives used in the European Union (EU) must only contain active substances in accordance with the Biocidal Products Regulation (BPR). The preservatives must also be approved by national chemical authorities, in Sweden the Chemicals Inspectorate (KemI).
The Swedish wood preserving industry has been very successful on export markets since the 1970s, and the export accounts for approximately 40 % of the total production. Treated sawn timber of spruce is the main commodity exported, and the most important market is the United Kingdom. To some extent, preservative-treated wood is also imported from Poland and the Baltic states.
Although “classic” preservative-treated wood still dominates the market for “durable timber”, relatively small amounts of naturally resistant species (mainly heartwood of pine and larch) and modified wood have attracted usage for residential applications as well as in the public sector. Most of the modified wood - acetylated radiata, furfurylated radiata/Scots pine and thermally modified – is imported. Some thermally modified is produced in Sweden, however. Swedish silica-based products are used both in industrial and superficial applications and marketed as “environmentally friendly” but there is doubt about their efficacy
Research in wood protection has a long tradition in Sweden with the College of Forestry/Agricultural University (SLU) playing a central role. SLU is still active but at a lower level than during the period 1960-2000. Small groups at a few other universities and RISE (formerly SP Technical Research Institute of Sweden) are also involved in research activities related to wood protection.
The Swedish Wood Preservation Association is the industry association representing Sweden’s wood preservation industry. There are 51 certified plants treating wood according to the NTR wood durability quality system , see below.
The Nordic Wood Preservation Council – NWPC is an organization for collaboration with respect to treatment specifications, quality control and certification of treated timber and efficacy approvals of wood preservatives to be used to treat according to the NTR wood durability quality system that is specified in the NTR-documents .
There are 110 certified plants from 10 countries treating wood according to the NTR standards and with the right and obligation to mark treated wood with the NTR-mark and respective NTR wood protection class. Total production of NTR-marked wood is approximately 2,3 million cubic meters per year.
Harmonized quality requirements for industrially preservative-treated wood have existed in the Nordic countries Denmark, Finland, Norway and Sweden since 1976, when a common Nordic standard for preservative-treated Scots pine wood was introduced after an initiative by the Nordic Wood Preservation Council (NWPC). More recently standards for treated spruce and modified wood have been introduced. An approval scheme for wood preservatives to be used for treating according to the Nordic standard was introduced by the NWPC in 1980. An approval scheme for modified wood has been introduced following the introduction of specifications for modified wood. To treat wood according to NWPC wood specifications requires affiliation to a quality control and certification scheme which includes third party inspections. Approximately 90% of the production of preservative-treated Scots pine in the Nordic countries takes place at treating companies that are affiliated to the NWPC quality control and certification scheme.
Germany is covered with 11.4 million hectares of forests, which is equivalent to 32 % of its land area. The total stock volume in German forests is 3.7 billion m³, the largest in Europe. Both, forest area and stock of wood are still rising. The states and the Federal Republic own 33 % of the forests, 48 % is in private hand, and the rest are corporate forests. Most prevalent wood species in German forests are Norway spruce (Picea abies), 25 %, Scots pine (Pinus sylvestris), 22 %, European beech (Fagus sylvatica), 15 %, English oak (Quercus robur), 10 %, and European larch (Larix decidua), 3 %. Norway spruce and Scots pine are the most relevant wood species for the building sector, but their shares are expected to decrease due to forest political strategies aiming at more mixed stands and a higher percentage of broadleaved forests.
In Germany, fungal decay is the major hazard for wood in use. In addition, attack by house longhorn beetle (Hylotrupes bajulus) and some other wood-borers’ larvae can occur. Except from a temporary and local occurrence in the city of Hamburg, the climate in Germany is still too harsh for subterranean termites. Along the German coastline, attack by shipworm (Teredo spp.) and gribble (Limnoria spp.) occurs. While the Baltic Sea had been considered shipworm-free for centuries, Teredo is now spreading East- and Northwards following an increase in salinity.
Germany is an important market for wood preservatives in Europe but there are no publicly available figures on the German wood preserving industry. However, few commercial treaters are organized within the “RAL - Gütegemeinschaft Imprägnierte Holzbauelemente” (RAL Quality Association: Impregnated Timber Construction Elements). Major market segments are the residential, agricultural and industrial applications (e.g. poles and sleepers) of vacuum pressure treated (vpt) wood, superficial treatments for construction timbers under roof (e.g. roofing timbers, joinery) or as base-coat under a coating (cladding and window frames), and the temporary treatment of freshly sawn timber against blue stain. In the vpt segment CC and CCB were dominating up to the mid 1990’s and is since then increasingly replaced by copper-organic wood preservatives, such as copper-quat, copper-azole and copper-HDO. Since 2017 chromium-containing wood preservatives are no longer on the market. Currently, the only remaining permitted use for creosote is for railway sleepers. There is currently no wood preservative treatment available for marine applications. For construction timbers in use classes 1 to 3.1, solvent-based products were mostly replaced by water-based emulsions containing azoles, quats, carbamates, morpholine and insecticides in the last 30 years. These products are mostly applied by dipping or (in-case of window frames) flow coating or spraying. Also, the temporary treatments are applied by dipping or spraying and contain the same actives (except for the insecticide).
As in other countries of the EU, all wood preservatives and active substances marketed must be approved under the Biocidal Products Regulation (BPR). The main wood species used for treatment are Scots pine, spruce and fir.
For residential applications exposed to severe weathering, besides pressure-treated wood, relatively small amounts of naturally resistant species (mainly heartwood of Douglas fir and larch) and modified wood are used, mostly above ground. Most common modifications are thermally modified timber (TMT) and acetylated radiata pine.
Since the mid-1990s wood preservatives with general building authority approval from the DIBt have been required by building regulations for the preventive protection of load-bearing wooden components or for combating wood-destroying organisms in structures. As the implementation of the BPR progresses, the DIBt will no longer issue any new approvals, only extensions of the existing ones for products that are not yet approved under BPR.
Timber for constructions in Germany is standardized by various standards e.g. EN 14081-1: Timber structures – Strength graded structural timber with rectangular cross section and in general EN 15228 (Structural timber preservative treated against biological attack). Detailed information on national regulation and treatment are given in DIN 68 800 (part 1- 4), which includes specific information for the use of timber for construction work with reference to the relevant EN standards. In particular part 3 regulates/specifies the requirements for wood preservatives and treated timber in relation to use classes. The standardization is undertaken by a committee located at the DIN (German Institute for Standardization) in Berlin. The committee members are representatives of institutes, universities, associations, authorities and industry.
Research in wood protection is a well-established subject at different institutions including the Thünen Institute of Wood Research (former BFH, Federal Research Center for Forestry and Forest Products) and the Center for Wood Science in Hamburg, the Georg-August-University in Göttingen, the Institut für Holztechnologie Dresden (IHD), the Fraunhofer Institute for Wood Research (Wilhelm-Klauditz-Institut, WKI) in Brunswick, and different universities in Brunswick, Dresden, Eberswalde, Hannover, Munich, Rosenheim, Rottenburg. Accredited test institutes for wood durability and wood preservatives are EPH Dresden, MPA Eberswalde and the BAM Federal Institute for Materials Research and Testing.
A committee of experts for wood protection (‘Deutscher Fachausschuss Holzschutz’) is organizing the German Wood Protection conference every second year – a two-day event with invited speakers and presentations addressing all facets of wood protection and wood preservation in Germany.
Canada is a major supplier of softwood lumber, including spruces, pines, true firs, hemlock, Douglas-fir and larch. Wood is typically marketed as species mixes, which include spruce-pine-fir (SPF), hem-fir, and Douglas-fir-larch. Naturally durable species include western red cedar, yellow cedar and eastern white cedar. Canada’s aspen resource is also used in the production of OSB. Most Canadian species are difficult to penetrate with preservatives. This challenge continues to shape the wood protection business and research in Canada.
Decay is the primary cause of biodegradation in Canada, though there are populations of subterranean termites in southern Ontario (Reticulitermes flavipes) and southern British Columbia (Reticulitermes hesperus). Marine borers are present in waters off the Atlantic and Pacific coasts.
Industrial preservatives used in Canada include creosote, PCP, CCA and CuN. In residential markets, MCA, CA-B and ACQ are the dominant preservatives. ZB is used for the protection of OSB. New preservative systems are typically first commercialized in USA before coming to Canada. There are a few small producers of thermally modified wood, and no production of chemically modified wood.
Wood Preservation Canada is the industry association representing Canada’s wood preservation industry. There are 53 certified treating plants in Canada spread across the country. The Canadian Wood Preservation Association hosts an annual meeting and serves as the national hub for wood protection research knowledge exchange.
Wood preservatives in Canada are regulated by Health Canada’s Pest Management Regulatory Agency. The CSA O80 standard includes specifications for treatments for Canadian species. It generally aligns with the AWPA approach to wood preservative standardization.
Wood protection research in Canada has historically been done at several Canadian universities. Currently the University of British Columbia and Université Laval are most active. FPInnovations, Canada’s national forest products laboratory, also has a team focused on wood protection research.
The wood protection market in the U.S. remains the world's largest, with a chemical value thought to be in the region of $1B USD, but this market is divided into a number of sectors and by geography. The significant sectors are industrial treatments for poles, railway crossties and marine applications, residential lumber for exterior applications, fire retardants for protection of interior wood products, remedial treatments for utility applications, and surface applied treatments for various uses, while powdered ZnB added to the furnish is used for the protection of various wood-based composite materials. The majority of exterior millwork is dip-treated after machining, but two commercial pressure plants using Teb/WR have been operational for over 16 years for the pretreatmnet of ponderosa pine stock prior to component manufacture.
Within the various product sectors mentioned above, by wood volume approximately 80% is residential lumber, 10% is poles and 10% railway ties. Wood modification has found modest usage for residential applications but this is mostly restricted to imported acetylated radiata pine from Europe. A venture to produce acetylated southern pine in the south ended soon after commercialization.
In the residential sector in the eastern US (the mostly southern pine region) MCA products dominate, while CA-C, DCOI/WR and PTI/WR systems have some market shares including in above ground appearance products. In the western US, ACQ and CA-C are the dominant treatments for the harder to treat Douglas fir and Hem-fir lumber used in that region. However, the presence of relatively naturally durable redwood and western red cedar lumber is a barrier to treated wood usage in this region. In general, whole house framing treatments with borate type products have found little market penetration in the mainland US, while where Coptotermes species, Reticultermes species and drywood termites are prevalent, such as in Florida, Louisiana and Hawaii, these types of treatment are more widespread. Borates are however commonly found in sill plate treatments which are usually mandated by building codes in the US. With regard to residential termite control specifically, this is mandated in much of the USA by building code and treatment is typically an integrated approach including the combination of design elements, pressure treated sill plate and a ‘termite preventive treatment’ all detailed in the building code. The termite preventive treatment can be pressure treated or naturally durable wood if used for the whole house, or more usually systems managed and applied by the professional pest control industry specifically being a traditional soil poison, a physical barrier, the use of termite bait stations, or topically applied glycol borates forming a two foot barrier to termite entry.
In the industrial sectors, CCA (along with some ACZA in the west) treated poles, piling and timbers still retain significant market share, although most poles are treated with oil-borne preservatives. In that regard creosote is still used somewhat for pole treatments while the majority of the oil-borne market is in the throes of a transition from PCP to CuN or DCOI as the preservative included. The EPA is currently phasing out PCP usage. In the crosstie market creosote remains dominant with some usage of CuN, especially for bridge ties Pretreatment of railway ties with borates to protect the inner zones has become commonplace prior to treatment with either oil based preservative system with some 60% of ties now subject to such pretreatment. Marine piling treatments are dominated by CCA (and ACZA) and creosote, along with some dual treatments as required depending on the type of marine borer hazard present.
Fire retardant usage is mainly in the interior sector of multi-unit developments, with the growing and significant opportunity in exterior applications remaining largely unfulfilled. Climate change and population growth have given rise to increasing fire hazards in urban wildland interface zones, especially in the western states.
On the regulatory side of wood protection in the US, the EPA requires that all biocides be registered prior to commercial use, and non-biocidal protection systems also require registration if the claimed usage triggers such regulation. The AWPA remains the primary standards writing body for wood protection in the US, as well as the primary technology transfer group in the field.
Research in wood protection in the US remains based in the universities and the Forest Products Lab of the USDA, while the chemical companies all retain research capacity. However, recent changes in corporate ownerships as well as program changes and retirements in the academic institutions have led to a lowering of overall research activity, especially with regard to the fundamental basic research in wood protection. Changes in academic emphasis ratings are also not favorable to research programs with a wood products focus.
Wood protection in Australia includes industrial treatments for poles and marine piling, an agricultural sector for vineyard posts, fencing and other structures, residential treatments for house framing and outdoor structures/landscaping, as well as an active remedial treatment sector for utility poles and some limited use of anti-sapstain treatments of raw timber. Three pressure treatment plants provide oil-borne or dual treatments for poles and marine structures in the industrial sector, but many others use waterborne treatments such as CCA, primarily for utility poles.. There are over 100 water borne treatment plants, most of which produce commodities for the residential applications markets only. Oil-borne treatments include creosote, PEC and furnace oil, while water borne systems include CCA, ACQ, CuAz, MCA, SP, Imidacloprid, and other copper quat systems. There is also a sizable market for LOSP treatments of joinery as well as decking, since this treatment system avoids the need for post-treatment drying.
In recent years the biggest growth area has been in house framing (H2) to protect it from termites. Framing is sprayed during processing with an insecticide (permethrin, bifenthrin or imidacloprid) and stained blue for ease of identification. This product is widely used in New South Wales and Queensland but also is used further south. The demand for vineyard posts and trellises fluctuates cyclically with Australia’s wine industry, but remains strong. Concerns about disposal are arising in some growing regions and will need to be addressed. Demand for hardwood poles remains strong, but supply issues have led to some substitution of radiata pine. Demand for outdoor treated timber is influenced by housing markets and fashions, while landscaping applications have been negatively impacted by increasing use of recycled products as well as by concerns about combustibility in bush fires. The last available financial data on the size of the wood protection chemicals market indicated it was greater than $50M AUD, and these numbers have presumably risen somewhat in recent years.
The dominant chemical suppliers to the wood protection industry in Australia are Lonza and Koppers Performance Chemicals. Azelis is a direct competitor to Lonza and KPC, while Kop-coat supplies proprietary Cu quat and Tru-Core systems. A distinct entity, Koppers Wood Protection, supplies mainly CCA and some creosote treated commodities such as poles and double-treated marine piles. Aside from the pressure treatment operations, in-line spray operations for termite treatments of house framing, and treatments of wood-based panels by, for example, glueline additives during board manufacture, are also carried out.
Australia also has an active remedial treatments sector which is separate from the above sectors.
Australia has a diverse climate running from temperate in the south to tropical exposures in the far north and is conducive to a wide variety of fungal and insect pests of timber and also marine borers. It is an island nation with a land area similar to the contiguous United States and greater than that of Europe. The population is spread very largely close to its 60,000km long coastline. The climate is predominantly continental with a tropical to temperate temperature range. These factors combine to present Australia’s preservation industry with both challenges and opportunities.
Wood preservatives in Australia are registered for use by the Australian Pesticides and Veterinary Medicines Authority (APVMA) which reviews toxicity and efficacy data; they are approved for treatment when incorporated into the national standard, AS/NZS 1604 series Specification for preservative treatment, one of three main standards that deal with wood protection in Australia. To protect the environment and wood from external pests, Australia has very strict quarantine regulations that are associated with the national standards for wood protection. Australia operates six Hazard Classes, equivalent to other countries' Use Categories, and all preservative treated wood purporting to comply with AS/NZS 1604 series must be marked with a brand that identifies the Hazard Class as well as the preservative used and the treatment plant where it was produced.
There is some use of modified timbers across the country, mostly produced offshore. Acetylated radiata pine has a small market share and furfurylated wood is available in the capital cities. Thermally modified timbers have a limited market because of their susceptibility totemite attack but at least one New Zeaand company (Abodo) markets thermally modified timber over-treated with a fungicide/insecticide. Wood plastic composites are also showing up on the market, but still have limited application because of high cost and an overall preference for hardwood decking.
Australia is a country driven by the periodic risk of bushfires and there are extensive standards regarding the use of timber in bushfire prone areas. However, very little fire-retardant treated wood is produced or used in the country. Instead, bushfire prone applications tend to use fire resistant hardwood timbers or clad the timber in fire resistant gypsum board. The use of intumescent coatings is growing, especially in mid-rise structures and there are discussions about the use of fire retardant treatments. This represents an area with tremendous growth potential given the increasing incidence of wildfires across the country.
Historically, preservation research and development was carried out in Australia by both Federal and State agencies, as well as the industry itself. Up until the late 1990s by far the biggest research effort was that of the Commonwealth Scientific and Industrial Research Organization (CSIRO) within the Division of Forest Products. The other major agencies conducting preservation research at that time included the Queensland Forest Service - Division of Technical Services, the New South Wales Forestry Commission - Wood Technology and Forest Research Division, and the Western Australia Conservation and Land Management Department. In addition, a number of University departments ran preservation research projects, e.g., the Australian National University, Melbourne University, and Queensland University of Technology. The CSIRO program is gone and most State programs have shrunk. Much of the expertise has been privatized. The largest remaining program is based out of the Queensland Department of Ag and Fisheries (DAF) in Salisbury which has an active program covering all areas of wood science. In addition, the University of Queensland (UQ) has active structural timber research underway including a very well-equipped fire lab. The University of Tasmania at Launceston has an active program to improve the durability of plantation hardwoods and there are efforts underway at the University of Melbourne and Southern Cross University as well as a large timber testing program at the University of South Australia. These programs are all largely supported by Forest and Wood Products Australia (FWPA) which is a quasi-governmental body funded through a combination of a levy on timber as well a government matching. FWPA has also recently funded a Durability Centre based out of the University of the Sunshine Coast in Queensland with DAF and UQ as partners in an effort to revive the research capacity in this sector.
Radiata pine, the main plantation forest species in New Zealand, is not naturally durable and therefore requires application of chemical or other means of modification to extend and preserve the life of timber products in service.
Historically, New Zealand has been recognised as a world leader in the field of wood preservation. This stems largely from the fact that for over 30 years, from 1955 to 1987, timber preservation in New Zealand was undertaken through regulations established in 1955 by an Act of Parliament. This established the Timber Preservation Authority (TPA), which had the sole right to publish treatment specifications, register timber treatment plants, and to revoke registration for serious transgression of the regulations. The TPA was replaced with an industry-based body, the New Zealand Timber Preservation Council Inc (TPC) in 1987. While not having the statutory powers of the TPA, it continued regulation and licensing of treatment plants. It reproduced the TPA's treatment specifications, with some amendments, which were published as a Miscellaneous Publication (MPO 3640) by Standards New Zealand. In 2003, this was reviewed to become NZS 3640 "Chemical Preservation of Round and Sawn Timber" and was linked to NZS 3602 (Timber and Wood-based Products for Use in Building). The use of timber that conforms with NZ Standard, NZS 3602 is the means of compliance with the New Zealand Building Code, Acceptable Solution B2/AS1, which specifies durability requirements of individual building components. NSZ 3602 refers to NZS 3640, which lists the approved preservative compounds, preservative minimum retentions and penetration requirements. Currently, in New Zealand, to ensure that treated or modified timber meets the required Standard, third-party auditing is a norm to oversee the quality assurance testing and procedures.
For a variety of reasons, including decay in untreated framing timber ("Leaky Building Syndrome"), which first came to light in 1999, a major revision of the TPC's specifications was undertaken in 2003. A radical departure from previous timber treatment specifications was the division of Hazard Classes, from H1 to H6. The H1 (inside, protected from the weather) and H3 (outside, above ground, exposed to the weather) into two sub-classes each. Whereas the original H1 classification applied only to preservative treatment to protect against insect attack, the new standard recognises that some framing timber may be exposed to a decay hazard owing to temporary lack of weathertightness of the building envelope. Thus, H1 became H1.1 (always dry, insect hazard only) and H1.2 (subject to intermittent wetting, insect and decay hazard).
Hazard Class H3 covers a very broad range of outside exposures from large structural members (exposed beams and joists) to less critical building components such as weatherboard, fascia and exterior window joinery. While the New Zealand Building Code (1992) requires a minimum of a 50-year durability for critical, difficult to replace components such as exposed beams, only a 15-year durability is required for non-structural elements. It is logical that preservation requirements for the latter need not be as stringent as preservation requirements for the former. Water-borne preservatives CCA, ACQ and CuAz and organic solvent-based copper naphthenate are approved for both 15-year durability (H3.1) and 50- year durability (H3.2) components.
ACQ and CuAz have both been registered and approved for use in New Zealand as alternatives to CCA for H3, H4 and H5 commodities. Since the alternatives are significantly more expensive than CCA, currently their use in high decay hazard situations is limited on economic grounds. There has been increasing use of LOSP as an alternative to CCA for H3 treatments. The advantage of LOSP is that no re-drying is required after treatment and the timber undergoes no dimensional change during treatment. A key export market for LOSP-treated timber is Australia where there has been acceptance of LOSP treatment for structural timber grades. In the domestic market, water and LOSP based Azole treatments are widely used for H3.1 applications such as cladding.
Currently, in New Zealand, over 90% of framing timber is treated with boron. Along with sawn timber, engineered wood products (EWPs) such as Laminated Veneer Lumber (LVL) are widely used for structural framing timber. LVL and other EWPs such as Cross-Laminated Timber (CLT) are becoming essential components of modern timber construction and have opened new possibilities for large format wooden buildings. A new development in the preservation of EWPs is the “Glue-line treatment”. A combination of Triadimefon and Cyproconazole as a glue-line additive has been approved in NZS 3640 for H1.2 application. The development of boron-based glue-line additive is also underway.
Attempts to impart durability (also dimensional stability) by means other than impregnating the timber with chemicals has been researched for a long time at the crown research institute, Scion. This includes wood modification techniques causing chemical changes in wood, either by using various chemical reagents (chemical modification) or by controlled application of heat (thermal modification at 180 to 260C). Various thermal modification products and process are commercially available such as ThermoWood® and Platowood®. Radiata pine is very amenable to this type of treatment and heating schedules for radiata pine are well developed. Thermally modified wood overtreating with other fungicide have a small market share by a number of small local companies. Currently trials are underway in New Zealand on developing heating schedules on several alternative species. Other modification processes with reactive chemical agents, for instance, acetylation with acetic anhydride (Accoya®) and furfurylation with furfuryl alcohol (KEBONY®) have been commercialised but not very widely used in New Zealand. Some other chemical modification technologies such as DMDHEU (dimethylol-dihydroxyethyleneurea) have also been introduced to the market.