28 | Sector Focus: Cladding & Shingles
◄ Abodo was formed in 2001 and remains a family-owned timber business, led by brothers Daniel and Nathan Gudsell. They started thermally modifying wood 15 years ago, with the two-fold objective of offering a durable alternative to chemically treated softwood and less abundant hardwoods and to make more of New Zealand’s plentiful supply of radiata pine.
“There was increasing awareness that a durable, sustainable, environmentally benign product was needed, particularly to substitute timber processed with such treatments as copper chrome arsenic, but also hardwoods from old-growth forests, where there is more limited supply and in some cases question marks over sustainability,” said Lewis Marshall, Abodo UK area manager. “There was also a desire to add value to radiata pine
in New Zealand and especially to develop the export market for further processed products rather than just logs.”
The focus on exports particularly was understandable given New Zealand produces three times as much radiata pine timber as it consumes domestically.
The country’s plantation forests cover around 6% of its land area, a total of 1.8 million ha. Of that, 90% is planted with radiata, with trees being ready for harvest at 27 years.
For some, the term plantation forest conjures the image of a sterile monoculture, supporting single tree species and little else in the way of wildlife and other flora. But Abodo says planted pine forests can provide long-term ecosystem benefits, not just timber, and a place for recreation, but also carbon
sequestration, water regulation, and soil stabilisation.
“Most of our wood comes from the Kaingaroa forest in the central North Island, one of the largest man-made plantation forests in the southern hemisphere,” said Mr Marshall. “It is all FSC-certified and the plantation managers are committed to supporting biodiversification and to land and soil conservation. Well-managed planted forests can maintain or even improve soil health while supporting a diverse range of organisms, plants and animals.” The company was not, of course, the first to thermally modify softwood, with Finland pioneering the process in the 1990s. “When the company was looking at ways of increasing radiata pine durability, chemical-free thermal modification stood out for us. And we acknowledge that the Finns led that space. However, we adapted the process specifically for radiata pine,” said Mr Marshall.
The Finnish method is largely used on European pine and spruce. These are respectively durability class 3 and 4 and are heated to between 190°C and 212°C to achieve a structural change at cellular level that increases moisture resistance and to degrade the wood’s hemi-cellulose, on which fungi feed. The end result is hardwood equivalent durability. “We took this approach and came up with our own specific schedule as radiata pine is durability class 5,” said Mr Marshall. “We ramp up the kiln temperature to 230°C, with the heat penetrating the wood at about 1mm per hour. Once the core is at 230°C, it’s held at that for a minimum of two hours. The moisture content at this stage is essentially zero. After this, the timber is slowly cooled, then reconditioned with steam, raising moisture content to a target of 6-7%. It will then remain at this equilibrium and the timber is transformed from durability class 5 to class 1.”
Abodo has developed the largest testing data suite for thermally modified radiata pine performance and submitted this to BM TRADA for evaluation. The company provides a 15-year ‘Built to Last’ warranty for its timber against all forms of fungal decay and BM TRADA concluded that, in uncoated form, it has an expected service life in above ground external applications of 30 years. Coated, this rises to 60 years. To achieve the accuracy required, Abodo starts its thermal modification process using diesel to heat its kilns.
Above: Vulcan is used for the exterior rainscreen and interior window framing, ceiling, shelving and decking of Dunlop Hub PHOTO: MICKEY ROSS
TTJ | January/February 2025 |
www.ttjonline.com
“Then, during the process, resins and other extractives come out of the wood and the residue is extracted to become an additional fuel for the boiler. The result is a self-fulfilling energy cycle,” said Mr Marshall. “The current process also gives us the opportunity to reduce our carbon footprint further with the
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