Once we’ve successfully removed the presence of termites from your home using colony location and destruction, dusting or baiting, we often recommend a chemical soil barrier treatment to reduce the risk of termites entering your building in the future.
To do this, we apply a liquid termiticide to the ground to saturation point using high volumes flooded into the soil. Timbers or house internals are not treated.
The idea is to create a barrier that prevents termites travelling through the soil and into the footings of a building. The chemical barrier is not intended to kill termites, nor will it kill termite nests. It also won’t stop termites from turning up in nearby areas that have not been treated.
It’s important to remember when considering this method that the soil under a timber floor building or slab will remain mostly untreated by the termiticide because the chemical is placed only against the building’s footings, stumps and/or directly against the slab edge. As a result, termites may still show up in stored goods under a treated house.
Is it a termite barrier or treated zone?
Chemical soil treatments are often called termite “barriers”. Historically this came about as many of the older chemicals were repellent to termites. Termites coming into contact with this treated soil around the home would be repelled by the chemical, preventing them from entering the home – an invisible, protective “barrier”.
However, it is important to understand that soil chemical treatments as with all termite treatments (chemical or physical) do not give 100% protection against termites entering your property. When they are installed correctly they are design to present CONCEALED termite entry – the termites cannot get in without becoming visible. For example, a treated zone in the soil around the home will prevent the termites tunnelling through the soil, but it does not stop them building a mud tube over the top of the soil to enter your home. However, when they do this, their presence can be detected (thus the importance of annual termite inspections) and they can then be dealt with.
It’s all about design
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 the dwelling 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.
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 excellent 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 can’t be. Your termite technician should be familiar with local building design and be able to make this assessment.
New age chemicals
Recently the chemical industry has introduced a new generation of termiticides that have re-vitalised this treatment.
These new chemicals do not create a repellent barrier that termites cannot crawl through. Instead they create a non-repellent “treated zone” through which termites pass, only to be contaminated in a way that passes toxicant to other termites. This indirect method of toxicity has the potential to kill an entire colony just by treating a nearby building.
We should warn you that it’s very difficult to quantify this indirect effect, and the product 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. Not surprisingly these new generation chemicals are more expensive than conventional repellent chemicals.
A last word on chemical barriers
Although termite colony control methods have improved dramatically over the past ten years, a continued trend to high density building is making protection of buildings with chemical barriers more difficult. We see little point in recommending a chemical barrier to a building where issues such as access mean that the barrier will not be reasonably complete. We do not like the idea of a 90% barrier because it gives a false sense of security.
In our experience, termites seem to be pretty good at finding the gaps!