A termite barrier is a physical object that keeps termites from penetrating the foundation of your house or accessing other parts of your property. These specially developed trenches and mesh coverings block termites from entering your home through the basement, footings, and foundation to reduce the chances that they reach your walls. A termite barrier is not an insecticide, termiticide, or chemical treatment.
One kind of termite barrier is a thin mesh, similar to the screen on windows that keeps out mosquitoes. This termite screen must be installed as houses are being built. A skilled installer will wrap the flexible screen around the bricks or slab of your foundation and against retaining walls and footings, both beneath and above the ground.
The screen is made of fibers that are indestructible to termite jaws. The holes between the weaving are too small to let a termite push its body through. A mesh barrier is not a guarantee against termite invasion, but it significantly reduces the possibility that subterranean types of termites will walk right up to your house, crawl through the foundation, and nest in timber walls.
Another termite barrier is made of perfectly shaped rocks. In this method, someone digs a trench around and underneath the boundaries of your foundation before the slab has been laid. They fill the trench with special granules that look like small pebbles. The granules are made of certain minerals with the appropriate density and weight, such as granite or basalt.
These carefully sized pebbles are selected because termites can't roll them aside. The bugs also can't squeeze between them or chew through them. Rock barriers are also predominantly effective against subterranean termites. The trench interrupts their only route to your foundation: the soil.
Termite barriers were developed in response to bans on popular insecticide sprays. Before these bans, chemical treatments of soil and rocks around the foundation were known as vapor barriers, but these have fallen out of favor. New termite barriers are environmentally friendlier and require very little maintenance. On the downside, they are most effective when installed before a house is built, so they aren't as successful on existing buildings.