What is Treated Lumber?

Low-cost, easy to work with, and easily available at nearly every big box building supply store; pressure-treated lumber is far and away the most popular deck building material across the United States.

But while it's still well-known, here at DecksDirect we tend to get asked quite often, "What is pressure-treated wood?"

Read through this quick DecksDirect Knowledge Builder post to learn more about treated wood and lumber including the benefits, uses, and warning notes. You'll be a DIY deck building pro in no time with backyard construction tips and tricks from the experts at DecksDirect!

Learn more about what is in treated lumber and the benefits of using treated material on your deck project

How is Pressure-Treated Wood Made?

The wood to be treated is entered into a large chamber or tank which will then be filled with the chosen chemical agent to treat the lumber. The tank then gets pressurized which forces the chemical to be absorbed deep into the wood fibers. When within the wood fibers, the chemical coats the material heightening the moisture-resistance of the wood inside and out.

Types of Wood Treatment

Originally the most common chemical combination used to treat lumber used to be chromated copper arsenate. In 2003, however, the EPA wisely stepped in to restrict the use of arsenic due to health regulations as treated lumber is often used in residential settings.

  • Alkaline Copper Quaternary (ACQ)
  • Sodium Borate (SBX)
  • Copper Azole (CA)
  • Micronized Copper Quaternary (MCQ)
  • Non-Combustible

Benefits of Treated Lumber

  • Moisture Resistance
  • Ease of Use
  • Variety of Sizes
  • High Availability
  • Fungal Resistance
  • Insect Resistance
  • Fire Resistance
  • Cost
  • Durability

Fasteners for Treated Wood

It's recommended that to only use hot-dipped galvanized or stainless-steel screws, fasteners, bolts, and anchors. There can be negative chemical reactions between non-coated metal hardware and the chemicals within the lumber.

Uses for Treated Wood

Treated lumber is commonly used all around the world for a variety of different DIY projects and backyard construction plans. From building decks and fences to sheds, picnic tables, or swing sets; pressure-treated wood is a low-cost option for the majority of outdoor projects.

Warning Notes on Pressure-Treated Wood

The chemicals in treated wood are generally not good for humans, animals, or fauna. It's recommended to wear gloves while handling and cutting treated lumber. Also, avoid inhaling the sawdust and refrain from burning treated wood.

Pressure-treated lumber is a low-cost deck frame material that provides a long-lasting outdoor space


Plan and design your ideal outdoor living space from the ground up with help from DecksDirect! Create a lasting and durable foundation for your home's backyard area with the sleek strength of a metal deck framing system. Or breathe new life to your deck, porch, or patio with a metal deck railing or glass railing renovation! With top-of-the-line deck products in stock and available to ship out the same day as ordered, the outdoor opportunities are endless with DecksDirect!

The more you know, the better your deck and backyard projects will be! To learn more about how to build your family's dream outdoor space or keep your home's deck in tip-top shape for decades, give one of our deck designers a call at 1-888-824-5316 or send us an email at hello@decksdirect.com. Our deck experts will help you get the information, products, and tools you need for a gorgeous deck that you created and designed!