CSI Section 06 15 36: Preserved-Wood Decking

Improving a wood’s durability through the use of preservative treatments extends its service life and reduces the 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.

More recently, micronized copper treatments have since 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. 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.

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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Wolmanized L3 Outdoor Arch Wood Protection, Inc. PureWood Bay Tree Technologies Cambia Heat-Crafted Lumber Cambia by Greenleaf EcoPrem Thermally Modified Wood EcoVantage Radiance Decking Radiance Wood Products	Wolmanized L3 Outdoor Arch Wood Protection, Inc.
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