DIY Dictionary: Green Treated

Updated: Mar. 14, 2024

What does ‘green treated’ refer to? Green treated refers to wood that’s had preservatives forced into it under pressure to help protect it against…

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What is Green Treated?

“Green treated” (aka pressure-treated) refers to wood that’s had preservatives forced into it, under pressure, to help protect it against decay and insect attacks. Today, the most commonly used preservative is ACQ—Alkaline Copper Quaternary. The copper in the solution is the chemical that imparts the green color; as the wood dries and reacts to sunlight, the color fades to gray.

Brown or “cedar tone” treated lumber may be either ACQ lumber treated with a brown stain or lumber treated using CA (Copper Azole).

The most important thing to know when purchasing any pressure-treated lumber is that they’re treated to various degrees of chemical retention levels. Common ratings include “ground contact,” “above ground” and “below-ground contact”; make sure to purchase the right material for the job. Steer clear of lumber and landscape timbers stamped or tagged “treated to refusal”; it’s a vague term and guarantees no specific level of treatment.