How Your Lumber Gets Treated

A few weeks ago, our team had the pleasure of learning more from the team at Madison Wood Preservers, who taught us more about their lumber treatment process and features about their lumber. Read more about how your lumber gets treated and why you should Count on Cardinal for your treated lumber!

Chemicals Used in Treatment

The type of lumber you buy from our stores uses one of two chemicals: Chromated Copper Arsenate (CCA) and Micronized Copper Azole (MCA). The CCA treatment cannot be used in residential settings, but is allowed in agriculture, highways, bridges, and marine applications. Some of the most common places you will see this are our ground contact fence posts (treated with .40 CCA) and critical structures like pole barns (.60 CCA). The other type of treatment, MCA, is used for above-ground and residential applications. In 2016, we shifted to selling only ground contact lumber. Please consult your Cardinal sales team member to assure you get the correct pressure treated lumber for your application.

The Treatment Process

Once the lumber is cut to dimension, stacks are banded together and put into a large pressure-treating cylinder. An initial vacuum pulls the air out of the wood, and pressure from the vacuum is used to push the treating solution from the storage tanks to fill the treatment cylinder. Once full, the cylinder is pushed to 165 – 180 psi for 7-9 minutes. A final vacuum is performed to empty the treatment cylinder and pull out any solution that was not taken up by the wood. In total, the process takes about 70 – 90 minutes. A diagram of the process is also available at cardinalhomecenter.com/lumber/.

Some of our lumber is also kiln-dried after treatment (KDAT), where it is dried in a chamber after being put through the vacuum. This dries the moisture content down to 19% moisture content on average. Lumber dried after treatment is less susceptible to warping, twisting, shrinking, and can be painted or stained right away.

Ground Contact Lumber

All of the treated lumber sold at our Madison and Crozet locations are treated for ground contact and can be used in situations both above ground or if it is in contact with the ground. It can also be used in areas that are above ground but are considered difficult to maintain, repair or replace and are critical to the performance and safety of the entire system/construction. Some of the most common uses include decking, beams and ledgers, posts, and step stringers.

Other Tips

• Use wood screws or face screw boards
• We recommend using double hot-dipped galvanized fasteners (meeting ASTM A 153) or better
• Use end coat solution to treat all cut ends, holes, or other intrusions
• Use a moisture meter to determine if your treated lumber has dried down to 19% moisture and is ready to be stained.
• Regular painting or staining is recommended for the longevity of treated wood projects

Have some more questions about pressure-treated lumber? Contact our Crozet or Madison stores to learn more about what we offer, or check out our newly reorganized lumber section on our e-commerce site, making it easier to find the dimension you need! Not quite sure what you need? Request a lumber quote from our experienced sales team.