Buying Guide

Benefits of Pressure Treated Wood

What Is Pressure Treated Wood?
person applying a stain to pressure treated wood

Pressure treating is a preservative process that helps wood withstand the elements and wards off termites, microorganisms and fungal decay, such as in pressure treated fence posts.

During the pressure-treating process, the wood preservatives are forced deep into the wood. The treating solution consists mostly of water. Because the treated wood absorbs a significant amount of water, depending on your location, it may take several weeks for the wood to dry. During this period, some shrinkage and warping may occur.

If you desire to paint or stain the treated wood project, it is important that the wood be dry enough to accept a coating. The best way to determine if the wood is sufficiently dry to paint or stain is to sprinkle droplets of water onto the wood. If the water droplets are absorbed, the wood is ready to be painted or stained. If the water droplets bead on the surface of the wood, it is too wet. You should wait a few days before attempting to paint and stain the wood. We have a broad selection of stain and paint products specifically formulated for treated wood.

Pressure-treated lumber can last 20 years or more, and most pressure treated wood comes with a residential and agricultural limited warranty.

What Is in Pressure Treated Wood?
termites in wood

The most common chemicals used to treat wood are Alkaline Copper Quaternary (ACQ), Copper Azole (CA), and Micronized Copper Azole (MCA).

Recent changes in the US treating standards now require Ground-Contact lumber for most end use applications, which has two times the preservative level as Above-Ground treated wood products. Ground-Contact treated wood is available at The Home Depot in most of our dimensional lumber and timber products.

Ground-Contact treated wood provides long-term protection against termite and fungal decay attack and can be used in most outdoor applications. 

ACQ/CA vs. MCA Pressure Treated Wood
ACQ/CA (Copper Azole) and Pressure Treated Wood
MCA (Microionized) and Pressure Treated Wood
Description Preservative Components: Primary biocide = copper amine, Secondary biocide = quat for ACQ/azole for CA Preservative Components: Primary biocide = microionized copper Secondary biocide = Azole
Feature/Benefits Protects Against: Fungal decay and termites Lifetime Limited Warranty Protects Against: Fungal decay and termites Lifetime Limited Warranty
Other Considerations Building Code Compliance: Yes, via AWPA or NER-628 (ACQ or ESR-1721(CA) Aluminum Compatibility: No Fasteners Recommendation: Hot-dipped galvanized (G-185) or better Building Code Compliance: Yes via International Code Council ESR-2240 and ESR-1721 Aluminum Compatibility: Yes Fasteners Recommendation: Hot-dipped galvanized (G-185) or better