Chemical Barriers

Once a colony control program has been provided (if possible) a chemical soil barrier treatment is often recommended in order to reduce the risk of termites entering the building in the future.

A liquid termiticide is applied to the soil to saturation point using high volumes flooded into the soil. Timbers or house internals are not treated. The intent is to create a repellant or toxic barrier that prevents termites travelling through the soil and into the footings of a building. Note that a barrier is not intended to kill termites, will not kill termite nests and will not stop termites from turning up in nearby areas that have not been treated. Also note that soil under a timber floor building will remain mostly uncontacted with termiticide and termites may still show up in stored goods under a treated house (the chemical is placed only against the building's footings) Photo - Trenching to external footing before application

In most buildings, a chemical soil barrier provides only one component of a termite barrier; the other components will be the building structures themselves. For instance, many buildings on concrete slabs are protected by a chemical treatment around the external perimeter only and rely on the integrity of the concrete slab to protect from under slab entry. Similarly, buildings with suspended timber floors and brick footings rely on their footings not having cracks and termite entry points up through the footings (the chemical can seldom protect all areas). A particular example of this is where a building has old timber stumps which have rotted or split at the bottom. These can allow termite entry from the bottom of the stump (where no treatment is possible), up into the building in complete concealment despite any chemical soil treatment.

While there are limitations to the performance of most chemical barriers they can provide reasonable protection to many buildings. The trick is to be able to identify when buildings can be reasonably protected with a soil treatment, and when they cannot be. A termite specialist should be familiar with local building design and be able to make this assessment. Photo - Chemical barrier application to external wall

New age chemicals - Even though chemical soil treatments have not changed much in 50 years, the chemical industry has introduced a new generation of termiticides that have re-vitalised this treatment.

These new chemicals do not create a repellant barrier that termites cannot crawl through. Instead they create a non-repellant "treated zone" through which termites pass, only to be contaminated in a way that passed toxicant to other termites. This indirect method of toxicity has the potential to kill an entire colony just by treating a nearby building.

Clients are warned that it is very difficult to quantify this indirect effect, and the labels make no claims in this regard. However, there is no doubt that these chemicals improve the results of soil treatments, and they tend to be used for the more difficult jobs. Naturally, they cost twice the price of conventional repellant chemicals.

Which Chemical to use?
Click here to see information about termite chemicals.