Buying Guide: Pressure Treated Lumber

Outdoor projects can be some of the most gratifying to tackle. Decks, fences and arbors (to name just a few) can provide years of entertainment, privacy and beauty. The material of choice for outdoor structures is, of course, wood. Not only is it beautiful, it's inexpensive, easy to work with and doesn't require any specialized tools. Equipped with a circular saw, drill and a hammer, you can build almost anything. The downfall? Wood makes a wonderful meal for the insects and bacteria for your backyard, and, left untreated can be destroyed within a few years. The Home Depot offers a wide assortment of pressure treated (PR) wood products for outdoor applications.

Protection from the Elements
To withstand the elements, wood is chemically protected through a process called pressure treating, which wards off insects, microorganisms and fungal decay. The most common types of chemical used to treat wood are Alkaline Copper Quaternary (ACQ), Copper Azole (CA), and, the newest type, Micronized Copper Quaternary (MCQ). Pressure treated lumber can last 20 years or more, and most pressure treated wood comes with a limited lifetime warranty.

Considerations Before Use
Pressure treated wood does require special considerations and usage. Here are some key requirements to keep in mind:

Fasteners
Due to the large amount of copper found in pressure treated wood, standard steel fasteners will corrode up to five times faster than when used in untreated wood. Opt instead for galvanized or stainless steel fasteners and metal components.

Shrinkage
During the ACQ and CA pressure treating process, wood becomes saturated with a chemical solution carried in water. After this process, the wood takes several months to dry. Be aware that there may be some shrinkage and warping as the lumber dries out. In addition, it may be necessary to wait anywhere from three weeks to six months prior to staining or painting, depending on the climate where you live and the treatment process the wood has undergone.