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Thermory Decking

Thermory wood decking is thermally modified for durability without the use of chemical preservatives… Read more
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  • Some materials provide a better alternative in an application dominated by products for which there are concerns about toxic constituents, intermediaries, or by-products. With the panoply of products made with polyvinyl chloride (PVC) and brominated flame retardants, some products are green simply because they provide an alternative. Examples of this are natural wall coverings, drain and vent piping, and roofing membranes. Some green products are free of hazards common to the product category; for example, LED lighting is inherently free of the mercury found in fluorescent lighting sources.

    However, it’s worth noting that without transparency about actual ingredients, there’s no guarantee that a product won’t have less common or less well-known hazards that the manufacturer isn’t talking about. We use Pharos’s Chemical and Material Library to assess less well-known hazards, and we encourage manufacturers to review the hazardous properties of all chemicals they use and seek out safer materials.

  • These products are environmentally attractive because they need to be replaced less frequently or their maintenance has very low impact, both of which can reduce costs as well as environmental impact.
    Robust answers on typical service life of products can be hard to come by, however. In GreenSpec we reserve this criterion for products where the material is clearly more durable than alternatives, such as an exceptionally traffic-resistant polyurethane floor finish. We refer to standardized tests for durability when they are available and appropriate.
    We also consider “appropriate durability”: long life is more important in a building envelope than in interior finish materials that will be replaced for aesthetic reasons. Here, reduced maintenance can be particularly important. An example is resilient flooring that doesn’t require regular waxing: an unnecessary use of resources and a health hazard.

Tristan Roberts
Editorial Director

Thermory wood decking is thermally modified for durability without the use of chemical preservatives. Heated to approximately 400°F in a process Thermory has used in Estonia since the 1990s, the decking is strength-tested at 14,000 lbs/in2 and, according to the company, will resist rot and insects for at least 25 years. Most Thermory decking is made of ash harvested and milled in the U.S. and then shipped to Estonia for thermal treatment, so decking shipped back for use in the U.S. has added embodied energy from transportation. The company does not currently offer FSC certified wood. Thermory decking is available in various sizes.

Preservative treatments extend the service life of wood and reduces demands on forests for replacement timber. Sales of lumber treated with the preservative CCA (chromated copper arsenate) are banned for consumer applications. Disposal by incineration is the most significant environmental concern associated with the billions of board feet already in use that were treated with this preservative: toxins such as arsenic may become airborne, and those that don’t get into the air end up in the ash, where they’re highly leachable. Soluble copper-based wood treatments, such as ACQ (ammoniacal copper quaternary) and copper azole, have replaced CCA as the industry standard.

As a delivery mechanism for chemical treatments, micronized copper has captured the majority of the wood preservative market. Micronized treatments use the same chemicals as soluble copper treatments but instead use tiny particles suspended in water. Studies show that this technology is less susceptible to leaching, making treatments more effective. All wood treated with copper should be avoided near aquatic ecosystems, since copper is highly toxic to many aquatic organisms. Copper-treated wood is also corrosive to steel fasteners; follow manufacturers’ recommendations for fastener selection, as well as treatment of end-cuts, which may expose less-treated inner wood.

Silica-based and thermally modified wood treatments are not actually preservatives but have the same effect by rendering the wood inedible to insects and fungi. Borate treatments effectively protect wood from insects while offering low mammalian and environmental toxicity; however, most borate-treated products are only suitable in weather-protected applications because the borates leach out when exposed to water.

Organic (carbon-based) pesticides, used in various combinations, also appear in treated wood, in both surface and pressure treatments. These agricultural pesticides offer a less-toxic alternative to copper-based treatments. Wood treated with copper or other pesticides should not be chipped for mulch, or burned.

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