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Which Wood Work? Difference in Pressure vs Untreated Lumber

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When you're working on a construction project, the type of lumber you use can make all the difference between an exceptional outcome and a failure that doesn't work well for your situation. How do you ensure you're getting the right lumber for your project? Our quick-start guide will give you the basics on the differences between pressure treated, untreated rot-resistant and untreated softwood lumber and the characteristics that may make it a good fit or a bad choice for your project. Let's get started.

Close up pressure treated lumber

In general, you'll want to use a rot-resistant lumber, whether naturally rot resistant or treated for rot resistance, for any lumber that is in contact with concrete or the ground. You may also want to use this type of lumber if it will be exposed to the elements, such as in a treehouse or patio, to ensure that you've protected your investment.

Characteristics of Pressure Treated Lumber

Pressure treated lumber has been treated to prevent rot and insect damage, making it ideal for contact with the earth or concrete, which can wick water and cause rotting issues in standard untreated softwood lumber. To create pressure treated lumber, untreated softwood lumber is placed in a vacuum chamber with a preservative agent, typically a copper- or boron-based compound that is much less toxic than yesteryear's arsenic-based compounds. The vacuum forces the compound deep into the wood, ensuring that the preservative goes throughout the wood. However, because of the added compound, pressure treated lumber is typically much heavier than untreated lumber and can be difficult to cut. It's also somewhat more expensive than untreated softwood lumber, but somewhat less expensive than naturally rot-resistant lumber.

Characteristics of Untreated Rot-Resistant Lumber

Some species of lumber has natural rot resistance, which may be a selling point if you have small children, animals that tend to chew on wood or other concerns about the preservative used in pressure treated lumber. These include redwood, western cedar, cypress, black locust and Pacific yew, with the first three species being the most commonly available and least expensive options to consider. However, the lumber will virtually always be more expensive than pressure treated lumber, but remains much lighter weight and easier to cut than its pressure treated counterpart.

Stacks of lumber in warehouse

Characteristics of Untreated Softwood Lumber

There are a few situations where you can substitute untreated softwood lumber in place of rot resistant options. If you're going to have contact with cement, you can sandwich 15# roofing felt between untreated lumber and the cement, with any protrusions sealed using a good-quality caulk that will prevent moisture from wicking through the protrusions. If you're planning on using this lumber for trim or outdoor use, painting it with a good-quality paint, preferably an oil-based enamel, will provide you with some protection against rot and insect damage, but will obviously add another step and expense to your project.

These three different types of lumber can meet a wide range of different needs, with the final decision usually based on environmental demands, desire for a more earth-friendly material and overall cost. If you have additional questions about these types of lumber or need additional information, please feel free to reach out to our experienced associates today. Whether you need advice, to place an order or to arrange for a job site delivery, Wallboard Supply Company is here to serve our customers.

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Wallboard Supply Company is a third generation, family run business that has been serving New England's building needs since 1970. Bob Filion started the company with a commitment to provide quality drywall and finishing products with unmatched customer service. The company has grown over the years, expanding its' product range, but never wavering from its' core values.