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When Should I Use Pressure-Treated Lumber?

Sep 16, 2020

Wood is a favorite material in home design, and it’s also one of the most used and adapted products in construction — modern architects have even designed skyscrapers out of wood. But the type of material that you build with matters, and if you’re designing a project that requires wood, you’ll need to determine when to use pressure-treated lumber.

It’s recommended for many outdoor projects, but there are other applications where pressure-treated lumber offers effective solutions. Understanding where and when to use pressure-treated wood could help to guarantee the success of your design.

Pressure-Treated Vs. Untreated Lumber

Wood has long been a popular building material, and pressure-treated lumber was invented in the last century as an upgrade to the traditional material. This treatment of lumber in the manufacturing process results in a highly durable and long-lasting building solution for all types of construction projects.

Pressure-treated lumber is the result of a process that uses high pressure to inject a preservative into the wood. It’s a process that extends the longevity of the wood considerably, adding decades to the life of the material.

The chemical preservative used in the process makes lumber resistant to insects and moisture, and it can even protect the wood in severe weather climates. There are 12 different levels of wood treatment, based on the three locations you intend to use the lumber: ground contact, above-ground use or marine use. You can see the chart of use categories on the American Wood Preservers Association (AWPA) site.

Because the wood is so durable, it’s recommended in many outdoor applications, and building code requires the use of pressure-treated wood in several instances.

When to Use Pressure-Treated Lumber

Pressure-treated lumber offers solutions to builders because it’s highly durable and won’t deteriorate as natural wood will. But building code dictates where you can use treated wood in applications — usually where there is risk of excessive moisture.

Generally speaking, any wood used in outdoor projects should be pressure-treated. Wood details in your interior design (like cabinetry or furniture) do not need the same level of treatment. In general, pressure-treated lumber is recommended in situations where there is direct contact between the wood and anything that could supply moisture:

  • Retaining walls, which function to support landscaping projects and hold back soil
  • Any posts or beams that come in contact with the ground or are buried underground
  • Lumber that touches concrete or masonry (since these materials are more porous)

Outdoor decks and landscaping projects (like garden beds) are often built with pressure-treated lumber because of its durability, but you’ll need to apply a sealant to the surface to prevent contact with the treated wood. “Most of the treated wood that’s two inches or less in thickness tends to be treated for above-ground uses, so it may not last very long in a ground-contact application,” says the AWPA.

Precautions When Using Pressure-Treated Lumber

The AWPA points out that how you use your wood will determine the kind of treatment that it needs. You’ll need to take extra steps to finish pressure-treated wood in indoor applications or outdoor projects that humans or pets might come into contact with.

“The chemicals in pressure-treated lumber are pesticides, so you should handle the wood with the same precautions as befit any potentially hazardous material,” writes Ruth Lively in Fine Gardening.

Protect yourself with gloves and face protection when you’re working with pressure-treated lumber, especially since the sawdust from cutting the wood can be an irritant. “Painting exposed wood surfaces with water-repellent finish, paint, or stain will protect your skin if you lean or kneel on the sides,” recommends Lively.

Solutions for Quality Pressure-Treated Lumber

Pressure-treated lumber is a durable and versatile material for homeowners that want an outdoor design that will last. Understanding how and when to use pressure-treated lumber will better ensure that your project is a success.

If you work with a trusted lumber dealer, they can help you determine the type of wood that you’ll need in your project.
Take a look at Talbert’s solutions for pressure-treated lumber or contact us directly for help with your project. Whether you are a builder or weekend DIYer, Talbert has the products and services to help you get the job done.