What is Pressure Treated Wood? Understanding the Basics

When it comes to building decks, docks, fences, or outdoor furniture, pressure-treated wood is one of the most versatile materials available. But what exactly is pressure-treated wood, and why is it such a popular choice for outdoor projects?

In this comprehensive guide from Decks & Docks, we’ll explore everything you need to know about this fantastic building material, including its uses, how it’s treated, and when to use pressure-treated lumber. Plus, we’ll provide helpful resources to ensure you’re making the best choice for your project.

What Is Pressure-Treated Wood?

Pressure-treated (PT) wood is lumber that has been chemically treated to resist rot, decay, and insect damage. This treatment process involves placing the wood in a pressure chamber and infusing it with a preservative solution that penetrates deep into the wood fibers. The result is a material that can withstand exposure to moisture and harsh outdoor conditions much longer than untreated wood, thanks to various pressure treatments available.

The pressure treatment process significantly enhances the lifespan of the wood, making it ideal for use in outdoor settings where durability is essential. However, not all wood called “pressure treated” is the same. For example, not all PT lumber is designed to withstand contact with salt water. Using freshwater-only lumber on an oceanside dock would spell disaster in just a few short years or maybe even months. Using improperly treated lumber is bad for the wood, the environment, and your wallet.

Understanding the classifications and grades of pressure-treated wood can help you choose the right type for your specific project.

What Is Pressure-Treated Wood Treated With?

The effectiveness of pressure-treated wood lies in the preservatives used during the process itself. Pressure-treated wood is treated with arsenic-based compounds like chromated copper arsenate (CCA) and copper-based compounds such as micronized copper azole (CA). These chemicals effectively prevent decay and deter termites and other pests. For marine applications, higher-grade treatments with more robust wood preservatives are often required to make wood cells withstand saltwater exposure.

The level of preservative treatment varies depending on the intended use of the wood, with higher concentrations of wood preservatives being used for applications that involve direct contact with soil or water.

Advantages of Pressure-Treated Wood

Pressure-treated wood offers numerous benefits over conventional wood that make it a popular choice for builders and homeowners alike:

• Durability: Treated wood lasts significantly longer than untreated wood, even in harsh conditions.
• Cost-Effective: Compared to alternatives like composite materials, pressure-treated lumber is more affordable. It’s more of an investment than traditional wood, but it pays off in the long run.
• Versatility: It’s available in various grades and sizes, making it suitable for a wide range of applications.
• Sustainability: Many treated wood products are made from renewable resources and are recyclable.

What Is Pressure-Treated Wood Used For?

Are you wondering when to use pressure-treated lumber? You can use pressure-treated wood for any outdoor projects if you need additional protection and longevity, thanks to its strength and resistance to environmental damage. It’s particularly exceptional for projects where the wood will be exposed to moisture, ground contact, or insects.

Outdoor Structures (Like Decks & Docks!)

Treated wood is rot-resistant and can be used for any structure exposed to the elements, such as decks, pergolas, or gazebos. It might also be used for playgrounds, sheds, walkways, garden boxes, benches, picnic tables, and other outdoor furniture. It’s particularly beneficial in coastal or humid areas.

Ground Contact Applications

Fence posts, landscaping timbers, wood foundations, and retaining walls often come into direct contact with soil, making pressure-treated wood essential.

Harsh Marine Environments

Pressure-treated wood treated for marine use (docks, piers, or seawalls and bulkheads) is a must to withstand saltwater and brackish environments.

Moisture-Prone Areas

If your project involves wood that will frequently get wet, such as garden beds, beams, wood foundations, or stair stringers, pressure-treated lumber is the ideal solution.

How to Choose the Right Kind of Pressure-Treated Lumber

Selecting the right pressure-treated wood means considering the type of structure, environmental conditions, and budget. You also need to consider the wood species, lumber grade, and how it’s treated; the appropriate grade and treatment level are critical to ensure the wood performs well in its intended environment. Avoid comparing boards just on price! It’s important to do a little homework (or call us at Decks & Docks!) before buying any pressure-treated wood.

Furthermore, Copper Azole Type C (CA-C) pressure treatment offers enhanced protection against termites and decay. It’s good for saltwater splash, giving an advantage for dock construction projects. 

Wood Type

At Decks & Docks, our top choice for many projects is pressure-treated Southern Yellow Pine. This versatile and durable lumber is well-suited for a variety of construction needs, looks great, and lasts for decades.

Pressure-treated Southern Yellow Pine features:

• Resistance to Rot, Pests, and Water Damage: Copper-based treatments provide robust protection against decay, mold, marine organisms, and the corrosive effects of saltwater, making it ideal for marine environments and humid climates.
• Suitable for Ground Contact: Whether you’re building on land or near the water, this type of treated wood is a reliable choice. CA Type C treatment is also approved for land-based projects like decks, wooden walkways, and other projects that come in direct contact with the ground.
• Built to Last: Pressure-treated Southern Yellow Pine is exceptionally long-lasting, making it ideal for projects that need to withstand the test of time.

Lumber Grade

Lumber grades tell you the number of knots, imperfections, and the straightness of the wood grain. At Decks & Docks, we only sell the higher grades of lumber, which means fewer knots, consistent boards, and longer life.

Type of Wood Treatment

Chemical treatment levels affect how long wood will last in marine or other harsh environments. For example, if you are building near water or ground level, look for a PT wood that is approved for ground contact. If you are building on or near salt water, look for marine-grade PT wood. 

The American Wood Protection Association (AWPA) is a non-profit organization that has long set the standards for treated wood used in residential and commercial applications. The AWPA classifies wood treatment types according to where and how they can be used. Always check the tags on the end of the boards to get critical information about the pressure treatment.

Shop Premium Pressure-Treated Lumber from Decks & Docks

Pressure-treated wood is an essential material for outdoor construction projects, offering unparalleled durability and resistance to decay. Whether you’re building a new deck, repairing a dock, or constructing a fence, make sure your investment lasts—buy PT wood from us at Decks & Docks, your go-to source for high-quality pressure-treated wood and expert advice.

Explore our selection of marine-grade and pressure-treated lumber today. Give us a call, and let us help you build something that lasts!