VANCOUVER, Wash. — Researchers at Oregon State University have confirmed decks built with today’s pressure-treated preserved wood products cause no environmental harm from preservative chemicals leaching from the wood and into rainwater or surrounding soil.
The researchers collected runoff and soil samples the first and fourth years after construction of a deck built with wood pressure treated with Copper Azole (CA-C), the preservative used to treat the preserved wood sold for decks and other residential projects. The deck is located in Oregon’s Willamette Valley, where rainfall measures 40-60 inches each year. Sampling began with the first rains after the deck surface was completed in October 2021.
Samples were analyzed for concentrations of copper, the primary active ingredient in CA-C. The highest copper concentrations were found in samples taken at the very start of the study, shortly after the deck was completed. According to lead researcher Dr. Gerald Presley, that was to be expected…