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Maximising the Service Life of Pressure-Treated Timber Posts

Maximising the Service Life of Pressure-Treated Timber Posts

Pressure-treated timber fence posts are typically supplied to achieve one of two desired service life (DSL) specifications — 15 years or 30 years — depending on the level of preservative treatment and intended use. Across most fencing applications, the 15-year specification remains the industry standard.

For projects that demand greater longevity or reduced maintenance costs, additional protection can be provided through the use of a ground-line barrier system. Such systems target the most vulnerable section of the post — the area at or just below ground level where moisture, oxygen, and fungi interact to cause decay.

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How Ground-Line Barrier Systems Work

Effective barrier systems function by forming a continuous, watertight and airtight seal around the post at ground level. By excluding oxygen and moisture, they effectively help to prevent the environmental conditions that allow rot and decay to develop.​

High-performance systems feature a bituminous inner layer that bonds permanently to the timber surface, providing an additional level of protection against microbial attack and moisture ingress.

Why Complete Sealing Matters

It is important to note that partial barrier approaches- such as wrapping posts with plastic bags, tapes, or flash bands - do not provide a complete or durable seal. These improvised methods can trap moisture against the timber, which may accelerate rather than prevent the risk of decay.

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*All Posts Submerged in The Same Water Containing Blue Ink for 6 Months.

Installation and Applications

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Modern barrier systems are compatible with standard installation techniques, including driving, backfilling or concreting posts into place. When correctly installed, they do not affect handling or structural performance.

The same proven technology is also used in larger-scale applications, such as utility poles and structural timber supports, where long-term durability and regulatory compliance are essential.

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