A Focus on AS3660.1

AS3660.1 offers a variety of physical and chemical barrier systems deemed to meet BCA requirements. It is important to realise these barriers only deter hidden entry by termites into buildings – they do not keep termites out. Therefore the longer term emphasis is on using the barriers to identify termite entry, and this relies on the building owner having regular inspections conducted – usually by engaging a termite management professional.

Physical barriers involve installing an impregnable material wherever subterranean termites might enter the building from
underground. The barrier blocks termite access, forcing them to build visible mud shelter tubes around the outside of the barrier. Regular inspections can detect the mud shelter tubes which can then be dealt with accordingly. Barrier options under this approach include:

• Concrete slabs (slab) – solid concrete units constructed to prevent termite penetration; must be built to Australian Standard AS2870 (with effective termite barriers fitted to all slab penetrations).

• Crushed stone (stone) – layer of stone particles too hard and heavy for termites to penetrate or move.

• Sheet cappings (cap) – sheet material (e.g. metal) used as an isolated or continuous sub-floor barrier.
• Stainless steel mesh (mesh) – termite proof mesh used as an isolated or continuous barrier.
  

Chemical barriers use termiticides that kill or repel termites before they enter the building. The barriers are commonly applied to the soil immediately around and beneath slabs and footings. Long life chemicals are no longer registered for this use due to the impact they were found to have on health and the environment. These days, the chemicals do not last the lifetime of the building, and must be periodically reapplied to maintain protection. Options arising from this include:

• Hand sprayed chemicals – this approach generally requires permanent access to all areas of the barrier for re-application purposes.
• Reticulation systems – this approach uses dedicated pipework hidden in the construction or beneath it, which allows re-application without the same need for access. 

Examples of physical and chemical barriers applied to common floor construction situations are shown in Fig 4 to Fig 8.

Important Note:

Combinations of the following options may be used as required. The options may also be used in combination with termite resistant materials. In all cases a continuous system must be achieved. Systems suppliers should be consulted to obtain appropriate design details as required.

All barriers or combinations of barriers are ‘detection systems’ intended to expose concealed termite activity. Consequently, they must be complemented by appropriate ‘inspection zones’. Regular inspections must be undertaken to detect evidence of termites, and therefore complete the system.

Fig 4: Suspended floors with ant cappings

Fig 5: Suspended floors with alternative barrier systems

Fig 6: Slab on-ground with exposed edge

Fig 7: Slab on-ground with covered edge

Fig 8: Slab on-ground with separate barrier beneath