Treated Lumber Series: A Guide to Pressure-Treated Lumber

Jim Coshow smiling.

"We’re lucky to have long-standing relationships with experts like Dennis. His deep understanding of treated wood and its nuances is unbeatable and will help you find success when working with this essential material."

- Jim Coshow


With any construction project, the goal is always to create something that retains its quality as long as possible—that means using strong, durable materials. This is especially true here in the Pacific Northwest, where homes and outdoor living spaces are exposed to more rain and damp air than most other places.

Treating lumber is one of the best things we can do to extend the lifespan of our greatest renewable resource—but when it comes to usage and best practices, there are key differences between treated and untreated lumber that you need to know in order to realize the full benefit of choosing this material.

To help us understand the nuances and need-to-knows about treated lumber, we brought in long-time industry expert and friend Dennis McWhirter of Exterior Wood. Dennis has been in the treated lumber industry for more than 30 years and we've worked with him through his many roles within the manufacturing process. Our treated lumber series documents our conversations with Dennis about the facts, best practices, and tips for project success.

We gathered our top four videos from the series below; if you only have time to watch a few, we recommend starting with these.

Part 1: How is pressure-treated lumber made?

The process of treating lumber has changed a lot since its inception. Where it used to be carried out manually using buttons, knobs, and gauges, now the entire process is computerized and happens fairly quickly. This video provides an overview of the treatment process. (For a more detailed breakdown, check out our detailed summary of the manufacturing process.)

Watch Video

Pressure treated lumber being moved by forklift.

Part 4: The difference between professional and premium-grade all-purpose construction lumber

All treated lumber is not created equal. When purchasing treated lumber, it’s important to understand the grading standards used by the manufacturer. In this video, Dennis explains how lumber is graded at Exterior Wood when manufacturing their premium-grade all-purpose construction lumber.

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Person in lumber manufacturing facility.

Part 5: Is pressure-treated lumber safe?

There are some common misconceptions about the safety of pressure-treated wood. In this video, Dennis shares facts about the treatment process they use, the chemicals involved, and how safe their pressure-treated lumber really is. To learn more about safety when using treated lumber, check out our interview with Dennis on whether or not you can burn treated lumber.

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Pressure-treated lumber in manufacturing facility.

Part 8: How to protect the lifetime warranty of pressure-treated lumber

Most of our pressure-treated wood has a lifetime warranty—but you’re only eligible if you treat the product correctly. In this video, Dennis shares tips and best practices for treated lumber usage that won’t void your warranty.

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Pressure-treated lumber.

Watch the full series

If you’re eager to learn more about treated lumber and its uses and best practices, check out the rest of the videos in this series:

Our goal here at Dunn Solutions is to provide you with trusted industry knowledge to help you find success on the projects you take on, and we hope these videos offer new and helpful information.