What new material is being used in treating wood that is called “treated”?
Michael Dresdner: As you seem to already know, CCA (chromated copper arsenate), the traditional material used in making pressure treated wood, was banned for residential use by the EPA on January 1, 2004, though it can still be used for permanent wood foundations and certain industrial and agricultural uses. Replacing it are two waterborne compounds; copper azole (CBA-A, CA-B) and alkaline copper quat (ACQ types B and D). Because they use much higher levels of copper to make them work, and because copper is so pricey, they are more expensive than the old CCA-treated wood. No doubt you have noticed the price increase at your wood supplier. Now, at least, you know why.