Chemically-treated timbers do not biodegrade and cannot be burned, which leads to the problem of disposal at the end of its life. Combined with the toxic chemicals many mainstream construction timbers are treated with, they’re often not harvested from sustainable sources. Because of these two issues, the treated timber industry is doing far greater damage to the planet than many would care to understand. In New Zealand, we produce 800,000m3 of treated timber every year, so this is an issue of considerable size.

Many treated timbers aren’t designed to last more than a couple of decades either, so the wastage and extensive landfill levels are high as treated timbers are replaced after a relatively short time, and consistent maintenance is required to retain chemically-treated timbers’ initial aesthetic appeal.

Alternatives to chemically-treated timber are slowly emerging though, and while the technology is not yet perfect, there are options worth considering if you’re concerned about the fragility of our environment.

One particular alternative is timber that is modified with heat and steam, rather than chemicals, to make non-durable wood more durable for exterior use. “This is known as thermal modification,” Abodo’s Daniel Gudsell says. “These products contain no preservative chemicals and are safe for people and the environment.”

The process of thermal modification works in the same way traditional chemical treatment does, making non-durable timbers more durable. The key difference, though, is at the end of life, where it is biodegradable and not dangerous. “It also makes timbers more stable and attractive in terms of colour.”

Thermal modification is achieved by using steam and temperatures in excess of 190 degrees Celcius, but Daniel says the real trick is in the cooling and reconditioning phase. “The modification process requires a purpose-built computer-controlled kiln to ensure every piece of timber is modified to the correct specification and quality. At the end of the process, the moisture content of the timber is around 7 per cent, and the chemical and physical properties have been permanently changed.”

Abodo’s thermally modified product, Vulcan, has a dramatically increased durability and stability, and the process results in a unique deep brown colouration. “During the thermal modification process, many of the extractives are ‘cooked’ out of the wood so there is little chance of resin bleed in service. This, combined with a degrading of the sugar compound in the wood, means that the conditions for fungal growth are almost eliminated so it will not rot.”

Vulcan provides an expected minimum 30-year service life above ground in vertical cladding applications, and because of its changed physical condition, it improves thermal insulation by about 20 per cent compared to other similar products. “Vulcan is perfect for eco decking, cladding and weatherboard applications,” Daniel says.

The other benefit of Vulcan is that it stays stable unlike other products, which means considerably less maintenance is required over its lifetime to retain aesthetic appeal.

Thermally modified timber can be recycled at the end of its life and turned into a carbon neutral fuel, unlike traditionally treated timber. “For us, it’s about creating thinking about tomorrow. At the end of life, thermally modified wood can be returned to the earth. It can be mulched and will biodegrade safely,” Daniel says.

“Our vision is a future with wood where people’s living and working environments are built from the world’s only truly renewable building material. We need to remove unsustainable wood products and toxic preserved wood products from the construction landscape.”

If you’d like to know more about Abodo, their lifetime model and their chemical-free products, click here to view them on ArchiPro.