In 2000, a new Standard was adopted for termite risk management. The Building Code of Australia (BCA) requires a barrier to be installed where the primary building elements may be subject to subterranean termite attack. A primary building element is a member of a building that takes part of the building loads and includes roof, ceiling, floor, stairway and wall-framing (including bracing) as well as door jambs, window frames and reveals, architraves and skirting.
Other structures are also required to be provided with a suitable barrier against termite attack that contains any primary building elements that would be subject to an attack. This includes a free standing carport or garage which might often be overlooked.
There are two types of Termite Management Systems:
- Chemical; and
Chemical barriers may be applied either by hand spraying beneath and around a building or by using a reticulation system underneath a concrete slab.
Chemical spray is installed in two parts: Part A and Part B. The Part A treatment is completed as part of the site preparation prior to slab pour. Part B application is done around the perimeter when paving is established. A durable notice is then permanently fixed to the building in a prominent location, usually the meter box, to advise future homeowners and inspectors of the system/s installed for termite management.
Physical barriers may be divided into two categories: those for use with suspended floor systems and those for use with concrete slabs on the ground.
For suspended floors, the most common form of barrier is ant caps, or termite shields. This is a very thin metal shield placed on top of piers and foundation walls or timber posts.
For slab on ground construction, more care needs to be taken as inspection is either limited or not possible once the building is completed. The slab is considered a termite barrier. All penetrations (pipes) through the slab must have a collar embedded in the slab. The edge of the slab may be left exposed, or alternatively, a barrier can be installed in the cavity. An example of this barrier is stainless steel mesh.
Another physical management system is graded stone. It works on the principle that the particles are placed so as to block termite access into the building. The termites cannot find a path through the layer of stone. Similarly graded stone barriers may be used as a full barrier beneath a slab, for service penetrations and perimeter protection.
- Check the barrier in accordance with the Standard (Part A and Part B and durable notice).
- Ensure you maintain the barrier as per the installer requirements.
- Regular inspection is required to ensure the system is still effective and has not been breached. This should be done annually.
Information courtesy of Mike Harding, Member of Australian Building Codes Board’s Building Codes Committee.