What is a termite perimeter barrier?

Termite perimeter barriers prevent subterranean termites

A perimeter barrier is designed to prevent subterranean termites, which cause the most damage, from entering your home. I usually trench all around a property and then fill the trench with a non-repellent chemical designed to stop any termites from entering the house. In some areas where there is no direct access to dirt, I will need to drill a hole every 250 mm and insert 5 litres of chemicals through the concrete slab, tiles or bricks. These chemicals will then stay active in the earth for years, depending on the chemical and the concentration and this is a great way of protecting homes against termite invasion, however, installing a chemical perimeter barrier has its own challenges like when someone has inconsiderately placed something in the way such as an air-conditioning unit or a hot water tank!

Non-repellent chemicals

Non-repellent chemicals are less toxic and more effective than repellent chemicals but they are also much more expensive. If you are installing a chemical barrier, ask the technician what chemical he will be using and in what concentration. Do some research and get some quotes. It is sometimes worth spending extra money to ensure better and longer lasting results. Two of the best non-repellent chemicals that I am currently using are Altriset and Termidor.


Altriset is a nontoxic environmentally friendly product which works by affecting the termite’s muscles. Within 2 to 4 hours after termites encounter the chemical, their jaw muscles will get infected and they will stop eating. Altriset has a great ‘transference effect’, meaning that the chemical will move to other members of the colony during their social interaction.


Termidor, like other insecticides, affects insect’s nervous system. As Termidor is also a non-repellent termicide, termites won’t be able to alert each other in order to stay away from the infected area and by transferring the chemical to each other they slowly ensure the colony’s disintegration.

Before installing a termite perimeter

Before installing the line of defence like one of the chemical barriers above, you need to ensure that termites are not living inside your home. If a termite colony is residing near the bathroom where it gets water supply from, a perimeter termite barrier is not going to affect it as the termites will have any need to cross the barrier. A colony, for example, may have a queen in the roof void in a corner where a blocked guttering provides it with water. Installing a perimeter barrier in this circumstance, particularly with a repellent chemical, can have disastrous consequences as it may effectively trap the colony INSIDE the property. A thorough termite inspection is a prerequisite for a successful termite perimeter treatment and should be performed before embarking on the installation of the barrier.

Subfloor chemical barriers

Another termite barrier option is a subfloor barrier where the chemical barrier is installed in the subfloor area in order to prevent termites from entering the property through the subfloor. I have inspected thousands of home and 8 out of 10 times, I find subterranean termites coming inside homes through the subfloor. Rarely do they start their colony in the roof or inside the wall, this is why we pay special attention to the subfloor where possible. Of course some homes are built on slab and therefore there is no subfloor to spray, and in those cases a perimeter barrier, such as the chemical barriers discussed above, is recommended.

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