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Barriers and prevention

A barrier does not kill termites. It forces them into the open, where an inspection can find them.

Two side by side cross sections of a wall meeting the ground. On the left, with no barrier, a dashed path shows termites travelling inside the wall cavity with nothing visible from outside. On the right, a barrier is installed at the slab edge, and a mud tube in honey colour climbs the outside of the wall to get around it: that tube is what an inspection finds. A caption below explains that bridging, such as a garden bed built up over the edge or a path poured over the perimeter, covers the strip again and cancels the barrier.
A barrier buys detectability, not immunity. That is why every barrier comes with an inspection schedule attached.

Barriers do not stop termites — they stop concealed entry

This is the single most misunderstood idea in the subject. And it is written into the standard: a termite management system installed to AS 3660 is designed to deter concealed entry. Termites can still get in: but they have to build a visible mud tube around the barrier to do it, and that tube is what an inspection finds. A barrier buys you detectability, not immunity, and that is why every barrier comes with an inspection schedule attached.

Physical barriers are the ones built in. Stainless steel mesh and graded stone particle systems are laid at the points a slab or footing is penetrated (pipes, conduits, cavities, perimeter) because those penetrations are the concealed routes. They do not wear out and they do not need renewing, but they only exist where they were installed.

Chemical barriers create a treated soil zone instead. They can be installed at construction or retrofitted to an existing house. And they have a service life: the product breaks down, so the zone has to be renewed on a schedule. A reticulation system is a chemical barrier with the delivery built in. A pipe network in the soil that can be recharged without digging the perimeter up again, which is why it is commonly installed at build time.

Whatever the house has, three things decide whether it keeps working: that the barrier was installed correctly, that it is not bridged by something added later, and that it is inspected. Bridging is the usual failure: a garden bed built up over the weep holes, a slab extension poured against the wall, a path laid over the edge. Risk factors covers those.

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Sources

What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.