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What is GC wood?

Published in Treated Lumber 2 mins read

GC wood, often referred to as Ground-Contact lumber, is a type of wood specifically treated to withstand harsh environmental conditions, particularly when used near or in direct contact with the ground.

Understanding Ground-Contact Lumber

According to industry standards, Ground-contact lumber is pressure treated with chemicals to withstand the effects of being close to the ground, in contact with the ground, or exposed to continuous moisture. This rigorous treatment is what differentiates it from other types of treated lumber designed only for 'above-ground' use.

Why Use GC Wood?

The primary purpose of GC wood is durability and longevity in challenging outdoor settings. As the reference states, Ground contact lumber is made for outdoor projects where the wood is exposed to all types of weather or has a high potential for decay.

This makes it essential for applications where wood is constantly subjected to moisture, soil, insects, and fungal growth that would quickly degrade untreated or less-treated wood.

Typical Applications of GC Wood

Due to its resistance to rot, decay, and insect damage, GC wood is the required choice for structural components that are:

  • Buried in the ground (like fence posts or mailbox posts).
  • In contact with the ground (such as deck supports or landscaping timbers).
  • Located less than 6 inches above the ground.
  • Likely to trap moisture or be consistently wet, regardless of height (e.g., joists under a low deck).

Using the correct type of treated lumber, especially GC grade when required, is crucial for the safety, stability, and lifespan of your outdoor structures.

Key Feature Description
Treatment Level Higher level of chemical treatment
Environment Close to or in contact with ground, continuous moisture exposure
Resistance Enhanced protection against rot, decay, insects
Primary Use Structural elements in severe outdoor conditions

Choosing Ground-Contact lumber ensures that parts of your project most vulnerable to deterioration are adequately protected, providing peace of mind and reducing the need for frequent repairs or replacements.