Termite management under AS 3660 for Australian residential builds

What it is

A termite management system is the combination of physical and chemical barriers installed to deter prevent or detect subterranean termite entry into a building. AS 3660.1-2014 is the new construction standard. AS 3660.2-2017 is the existing building standard. AS 3660.3-2014 covers in service assessment criteria. The NCC Volume Two Part H1 (Structural) references AS 3660.1 as the deemed to satisfy solution for protection against termite attack in Class 1 and Class 10 buildings.

The NCC requires termite management in all areas of Australia except a small list of exempt locations defined by historic absence of subterranean termites. In practice every residential build in mainland Australia and Tasmania needs a termite management system designed installed and recorded under AS 3660.1.

What AS 3660.1 actually requires

The standard breaks termite management into two design approaches and two coverage zones.

Whole of building protection

A whole of building system creates a continuous barrier around every concealed point where termites could enter the structure. The barrier extends under the slab around penetrations around the perimeter and up to the lowest concealed timber. The system has to deny concealed entry across the entire footprint. Whole of building is the default approach for Class 1 builds.

Perimeter protection

A perimeter only system protects the outside edge of the building and relies on the slab itself as the internal barrier. Perimeter only is permissible where the slab is a Type A slab under AS 2870 with no penetrations or cracks wider than 1 mm and where all penetrations through the slab are protected by individual penetration sleeves or collars.

Physical barriers

A physical barrier uses material termites cannot chew through or detect through. The barrier sits at points where termites would otherwise have a concealed entry path.

The common physical barrier products are:

• Stainless steel mesh (typically 0.5 mm or finer aperture) used at slab penetrations and perimeter zones.
• Graded stone particle barriers under slabs and around perimeters.
• Marine grade composite collars at pipe penetrations.

Physical barriers carry product specific durability classes. A barrier rated as durable for the life of the building does not need replenishment. Some chemical reticulation systems are rated for 5 years before replenishment.

Chemical barriers

A chemical barrier uses a soil applied termiticide that kills or repels termites that try to cross the treated zone. The chemical can be applied as a soil treatment under the slab and around the perimeter or delivered through an in ground reticulation system that allows future replenishment.

Soil applied chemicals require the soil to be retreated when the chemical wears out. The product life sits between 5 and 8 years depending on chemical class and soil conditions. The owner is responsible for inspection and replenishment at the manufacturer specified intervals.

Durability classes

AS 3660.1 has two durability outcomes. The barrier is either rated for the design life of the building (typically 50 years) or rated for a defined service period after which replenishment is required.

The durability class governs the warranty and the homeowner inspection regime. A 50 year barrier still needs annual inspection. A 5 year chemical barrier needs replenishment plus annual inspection.

The compliance trail

A compliant termite management system in a new build needs:

• A design drawing showing the barrier type product and coverage zone.
• A pre pour inspection record showing the physical barrier installed before slab pour.
• A chemical application record (where applicable) showing product batch volume and application date.
• A durable notice fixed in the meter box or hot water service location stating the system type product installer date of installation and date for next inspection or replenishment.
• A certificate of installation from the installer.

The durable notice is the most overlooked item. It is mandated by AS 3660.1. Builders who skip the notice expose themselves to defect claims even where the underlying barrier is fully compliant.

How it links to warranty risk

Termite damage that occurs because the barrier was not installed to AS 3660.1 sits inside the major defect definition under most state warranty regimes. The damage is concealed structural damage. The cause is defective workmanship. The remedy is full rectification of the affected structural timbers.

A TradeLens audit pulls the AS 3660.1 design pre pour photo chemical application record installer certificate and durable notice photo. A build without any one of these documents carries elevated warranty risk for the duration of the warranty period.