Termites reportedly cause damage estimated at over $100mil. to Australian houses annually.
Of the 350 species of termites in Australia comprising Dampwood, Drywood and Subterranean types, the latter account for over 98% of all termite damage. Often referred to as 'white ants', the termite is more closely related to the cockroach.
The Building Code of Australia [BCA] requires that if there is a threat of termite attack, new homes must be provided with an approved method of protection.
The BCA references the Australian Standard 'AS3660 Termite management' which outlines the systems of control that will satisfy the requirement.
It should be noted that currently the BCA only regulates for protection of the structural elements of a building whereas previously under regulations, protection of the whole home was satisfied.
At the time of writing this article several amendments to the BCA are in progress. For example the Queensland requirement is now for 2 notices of termite treatment details be fixed to the building in prominent locations.Protection is extended to cover door jambs, window frames etc.
Readers should check with their relevant local government authority to ascertain current amendments and to determine if their site is included in a termite designated area.
Prior to 1995 the majority of homes in Australia were protected from termite attack by the use of organochlorines sprayed either under the membranes of concrete slabs or in the case of timber flooring systems, throughout the subfloor area generally at or before framing stage.
The banning of their use in July 1995 [ 8 to 10 years after their ban in the USA ] led to the change over to the use of a broad range of alternative methods.
Prior to 1995 both Termi-Mesh and Granitgard were 'approved systems' and included in the Australian Standards.
During 1995 'Dursban', a chlorpyrifos based product by DowElanco was approved by the National Registration Authority for both pre-slab hand sprayed treatment and for piped rechargeable systems. Since then, several other products have entered the market place.
All termite control methods under the Australian Standard are designed to force termite activity into the open where they can be detected during inspections. A termite barrier system constructed in accordance with this standard cannot prevent termite attack, as barriers may be bridged or breached.
Where termites bridge barriers the evidence may be detected during inspections.
None of the methods outlined in AS3660 will, nor are intended to eradicate termites.
The main point for home owners to be aware of is that when a home is built, it is the builders responsibility to install a termite protection system and to notify the owner of the type of system installed and its limitations. It is the owners responsibility to ensure that regular inspections are carried out and that the system is fully maintained.
For example a system such as termi-mesh, which is a physical barrier, and is advertised as outliving the life of your home, requires regular inspections to detect any activity of termites forced into the open as a result of the system.
A chemical perimeter barrier requires regular inspections and re-application of the chemical periodically, to maintain its effectiveness.
In the event of any termite infestation and damage, if a builder can show he has adhered to AS3660, then he will not be liable under the home owner warranty period or under common law which in some cases can extend for the life of the building.
The cost of repairs would be born by the owner.
There are various methods and systems available to implement for termite protection.
Regardless of which method is used, correct installation, inspection and maintenance of the system is essential to prevent termite intrusion.
There are basically 3 methods of protection employed.
This method employs both hand spraying and reticulation systems using chemicals approved by the National Registration Authority. In a concrete slab situation this can be implemented by - soaking of the under slab soil before the concrete is poured; installation of distribution pipes under the slab to enable periodic pumping of chemicals to the under slab soil; a perimeter spray after the slab is poured.
For above ground construction -
spraying of the soil around stumps footings and any other connection between the building and the soil [ eg pipes conduits etc]; distribution pipes around perimeter of the building for 'rechargeable application.
Employs materials such as 'termi-mesh' - a fine woven stainless steel mesh - 'granitgard' - finely graded stone particles - or galvanised steel such as used in ant caps.
For slab on ground situations normally the slab itself is used in conjunction with materials incorporated around penetrations such as wastepipes etc. and around the perimeter of the slab.
For above ground construction - the most common method is to employ ant caps and a continuous shield around the perimeter brickwork in the case of brick veneer construction.
For slab on ground construction a minimum of 75mm of slab edge is exposed to enable detection of termite activity. A physical barrier still needs to be incorporated on all internal slab penetrations.
For above ground construction a minimum clearance of 400mm below bearers is required to allow access for visual inspections. This may be reduced to 150mm providing that the area generally slopes to 400mm within 2met. of that point.
A combination of different types of barriers may be used - for example in the case of mixed construction methods.
It is important to understand that no system is meant to 'kill' termites. All barriers are put in place to force termite activity into the open.
Termites require moisture - prevent ponding of water around slabs and in sub floor areas.
Regular inspections for activity, leaking pipes, leaking down pipes etc. are all part of the process required to keep termites out of your home.
Queen and King (closer to front) with workers in attendance.
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