Pressure Treated Plywood: What You Need to Know

Pressure treated plywood is manufactured using a process that involves pressurizing the wood with chemicals to enhance its durability and resistance to rot, decay, and insects. Here’s a detailed overview of the manufacturing process:

1. Preparation: The plywood sheets are stacked and placed inside a specialized cylinder chamber known as a retort.
2. Evacuation: The retort is sealed, and a vacuum is created to remove air and moisture from the wood cells, allowing for better penetration of the chemicals.
3. Chemical Treatment: The retort is flooded with a preservative chemical solution, and pressure is applied to force the solution into the wood fibers. The pressure is maintained for a specific duration to ensure thorough penetration.
4. Retention Level: Pressure treated plywood is categorized based on its intended use, which determines the “retention level” or the quantity of chemicals retained post-treatment. Higher retention levels require longer exposure in the chamber.
5. Drying: After treatment, the pressure treated plywood is set aside to fully dry before distribution. This drying period contributes to the wood’s enhanced strength.
6. Safety: It’s important to note that pressure treated plywood manufactured before 2004 may have been treated with Chromated Copper Arsenate (CCA), which contains arsenic, chromium, and copper. Due to health concerns, CCA was phased out for residential use in 2003. Pressure treated plywood produced today uses safer chemicals and is considered safe for residential use.
7. Regulation: To ensure safety and quality, it’s recommended to only purchase pressure treated plywood with a regulated stamp of approval, indicating that it meets the required standards and does not contain harmful chemicals.

> Read more: Can You Stain Pressure Treated Wood? Expert Tips & Timing

What is pressure treated plywood good for?

Pressure treated plywood is usually reserved for wood that may come in to contact with excessive moisture. This wood can be used residentially for external wood such as, decking, fences, docks, or any other wood that would have prolonged exposure to water.

It can also be used in other industries as well. Construction industries will use pressure treated plywood in bridges, guardrails, or any other projects that need to be outdoors and withstand the elements.

There is a difference between wood that is above the ground and what touches the ground, or ground contact wood. Wood that will have ground contact will have to go through a longer process, so that it has twice the level of chemical retention compared to non-ground contact wood.

> Read more: Choosing The Best Plywood For Outdoor Use – VINAWOOD

3 Types of Pressure Treated Plywood

1. Borate: Borates are composed of sodium salts that are then used in a water-based solution. This chemical helps to keep the color of the wood and protect against mold, insects, and general breakdown. Since it is mixed with a water-based solution, it can start to leak out in rainy or wet areas. Best for dry locations.
2. Alkaline Copper Quaternary (ACQ): This is one of the most environmentally friendly options of the types of pressure treated plywood. It is made with soluble copper and quaternary ammonium alkyl. Protects against mold, insects, and general breakdown. It does change the color of the wood to a darker brown tone. There is no arsenic or chromium contained in this preservative.
3. Noncombustible Wood: This is wood that has been treated with a fire-retardant chemical before being pressurized. This is to help with flammability but does not completely take away risk. Can be used residentially or commercially, but not advised to be painted because it may affect the way it performs.

> Read more: Plywood Deck: A Guide to Installation and Waterproofing for Indoor and Outdoor Use

FAQ

How long will pressure treated plywood last outside?

The lifespan of pressure treated plywood outside can vary depending on several factors, such as the quality of the treatment, environmental conditions, and how well the plywood is maintained. On average, pressure treated plywood can last anywhere from 20 to 30 years or more when used in outdoor applications. Proper installation, regular maintenance, and protection from prolonged exposure to moisture and sunlight can help extend the lifespan of pressure treated plywood.

Can pressure treated plywood get rained on?

Yes, pressure treated plywood can get rained on without significant damage. The treatment process makes the plywood more resistant to moisture, rot, and decay, allowing it to withstand exposure to rain and other outdoor elements. However, prolonged exposure to standing water or constant moisture can still lead to deterioration over time. It’s important to ensure proper drainage and ventilation to prevent water from pooling on or around the plywood. Regular maintenance, such as applying a water-repellent sealant, can also help prolong its lifespan when used in outdoor settings.

> Read more: What Is Marine Grade Plywood? Is Marine Plywood Waterproof?

Reputable suppliers know the difference between marine-grade plywood and high grades of traditional pressure-treated plywood. At Vinawood, our clients can trust the materials we supply for their projects because we understand the importance of every job. Vinawood is known as a leading provider of industrial wood and packaging solutions. Specializing in cut lumber needed for pallets, crates, skid parts, fully assembled custom pallets, integrated packaging solutions, and other services that can be tailored to each individual customer.