Pressure treatment is a method used extensively in the wood industry to protect timber from decay, pests, and weathering. Through this process, wood can last longer, making it a vital procedure for enhancing the durability and longevity of wood products used outdoors or in moisture-prone environments. This blog post will guide you through the process of pressure treatment, its benefits, types, and considerations for use.

What is Pressure Treatment?

Pressure treatment, also known as pressure-preservative treatment, involves infusing chemical preservatives into wood, making it resistant to rot, decay, insects, and microbial agents. The process uses a high-pressure technique to ensure that the preservative penetrates deep into the wood fibres, providing long-lasting protection.

How Does the Procedure Work?

The procedure for pressure treating wood usually follows these steps:

  1. Preparation: Wood is first prepared by being cleaned and possibly planed to ensure the chemical can penetrate properly.
  2. Preservative Application: The wood is then placed into a large, cylindrical pressure chamber where air and moisture are vacuumed out.
  3. Pressurisation: The preservative is introduced, and the chamber is pressurised, forcing the chemicals deep into the wood's structure.
  4. Post-Treatment: Once the treatment is complete, the wood is removed and left to dry, locking the preservative in place.

Types of Preservatives Used

  • Alkaline Copper Quaternary (ACQ): An eco-friendly option that does not contain arsenic or chromium.
  • Copper Azole (CA): Similar to ACQ, this preservative is effective against decay and insects and is safe for residential use.
  • Creosote: Used primarily for industrial purposes, such as for railroad ties or utility poles, due to its strong preservative qualities.
  • Chromated Copper Arsenate (CCA): Although effective, it has been phased out for residential use due to health concerns associated with arsenic.

Benefits of Pressure-Treated Wood

  • Durability: Treated wood can withstand harsh environmental conditions, including moisture, fungal decay, and pests.
  • Cost-Effectiveness: It offers a longer lifespan compared to non-treated wood, which means reduced costs over time for replacements and repairs.
  • Versatility: Pressure-treated wood can be used in various applications, from outdoor decking to fencing and landscaping projects.
  • Safety: When used appropriately, treated wood is safe for residential use and offers protection against potential threats like termites and fungal decay.

Applications of Pressure-Treated Wood

Given its enhanced durability and resistance to decay, pressure-treated wood is ideal for outdoor and structural applications. Common uses include:

  • Decks and patios
  • Fences and rails
  • Landscaping structures such as retaining walls and garden beds
  • Outdoor furniture
  • Structural supports in buildings

Considerations and Safety Measures

While pressure-treated timber offers numerous benefits, there are considerations to keep in mind:

  • Handling and Working: When cutting, drilling, or sanding treated wood, it's important to wear protective gear to avoid inhaling sawdust or causing skin irritation.
  • Disposal: Because of the chemicals used, treated wood requires special disposal methods. It should not be burned in open fires or stoves.
  • Environmental Impact: Select treated wood certified by environmental standards to ensure it has a reduced impact on the environment.


Understanding the key facts about pressure treatment is essential for anyone involved in construction, landscaping, or any project that utilises wood. By selecting the right type of treated wood for your needs and following proper handling guidelines, you can ensure the longevity and safety of your wood structures, ultimately making sustainable and cost-effective choices for your projects.