Treated Wood Susceptible to Rot, Says Study

A study published in

Forest Products Journal in June 2007 found that wood treated with copper azole or alkaline copper quaternary compound (ACQ) to both above-ground and ground-contact levels is prone to damage from brown-rot fungi. Both chemicals were introduced to replace chromated copper arsenate for residential use several years ago (see

EBN

Vol. 15, No. 8) and together are the current industry standard. Test samples treated with both chemicals lost 20%–60% of their mass due to rot; the study concludes that wood treated to current standards may not be adequately protected. While gathering samples for the study, researchers found that wood treated to higher-retention ground-contact levels was not available at many lumberyards, suggesting that many consumers are using lower retention treated wood in ground-contact applications, creating even greater risk for rot.