Many people think of termites as aggressive destroyers of homes and property, but about 90 percent of termite species are beneficial. They consume, digest and make use of dead and dying vegetation. Some species also eat the waste of herbivores, which can contain undigested cellulose. In some places, termites are the most important factor in breaking down cellulose. Without them, dead trees and herbivore waste wouldn’t decompose normally — they would gradually pile up, making it harder for animals to migrate and find food.
Many homes and other human structures fit the bill for termite food because they’re made of dead wood. Termites can’t differentiate between the inside of a dead tree and the walls of a person’s house. In some parts of the world, termite attacks on homes are so prevalent that people have adapted, building their homes on stilts lined with termite deterrents, like pieces of metal and pie pans. A termite shield is a sheet metal fabrication used in light frame construction to reduce the movement of termites from the soil into wood framing members such as floor joists and studs. Although there are several types of non chemical termite barriers now in use, termite shields are the original.
Termite shields can be made up of various materials. One type of termite shield is made from various sheet metals including galvanized steel, terne, copper, or aluminum. The metal is formed to fit between the top of the foundation wall and the bottom of the wood sole plate. The edges of the termite shield are typically hemmed, extended slightly beyond the face of the wall, and turned down to form a drip edge which diverts water running down the face of the wall and reduce the movement of subterranean termites from the soil up into the wood framing members. Termite shields will not protect a building from termite activity, but help make termite activity more visible. One problem with termite shields is the gaps which exist at seams and at openings where steel reinforcing bars penetrate the metal shield. Since many species of subterranean termites can enter through openings >1/20 Inch (1.27 mm), these gaps must be sealed with a sealant known to block termites. Additionally, termite barrier sealant should be used underneath the shield, so termites are forced to go to the exterior of the structures. There are two other materials called “termite barriers” rather than “termite shields” which have been evaluated by the International Code Council. One is a waterproofing membrane, and the other is a wire mesh.
Termite barriers are materials that have been specifically designed to prevent subterranean termites from gaining access to a structure. Physical termite barriers are free of pesticides and physically block termite foraging activity. Development of physical barriers to effectively exclude subterranean termites makes it possible to design and build structures with a far lower possibility of termite invasion and damage over the life of the building. Because of their tiny size (0.02 inches or 0.05 cm), impressive reproductive capability (a termite queen products one egg every 3 seconds, or over 10 million eggs per year) https://blogs.scientificamerican.com/running-ponies/long-live-the-morbidly-obese-termite-queen-and-her-terrifying-army-of-sweat-licking-babies/, and ability to eat through many construction materials, termites are the most destructive of all insects Pest Control Technology; https://www.pctonline.com/article/pct0215-annual-termite-damage-quest/. Termites are considered the most invasive of insects, so if you can block them, you will block almost all other insects. Termite membrane barriers consist of elastomeric sealants adhered to a high-strength backing. When included in the building envelope, membrane barriers perform multiple functions. In addition to excluding termites and insects, they act as waterproofing, air barrier, and vapor barrier. Applications for termite membranes include on concrete foundation walls, ICF insulated concrete forms, under-slab waterproofing, under-sill plates, flooring underlayments, and as wall, window, and door flashings, among others. Most termite membranes must be implemented during the construction process.
Termite shields, an early physical barrier, are sheet metal fabrications used for decades in light frame construction. Termite shields are often applied underneath wood sill plates. They are designed to force termites to build their mud tubes outside of the structure, where they become visible to a trained pest management professional.
Lately, granite and Polyvinyl chloride (PVC) shield can be installed into tiny brick open spaces where termites can enter the building surrounding the whole perimeter of the property. The termite shield is too thick for the termites to chew and penetrate the material forcing the termites to migrate into the open where they can be more easily eradicated. The benefits of using this type of material is that they are sustainable to the environment being awarded Environmental Choice Declaration from the Environmental Labelling Association.[3] Other benefits include being cheaper than metals, and can be coupled with other shield protection systems.
Termite sealant materials are the basic component of termite membranes described above. Sealants are elastomeric, meaning they move with the structure without tearing, and are available in a caulk or spreadable formulation. When caulked around a plumbing penetration in a structure, termite sealant barriers adhere to both the pipe and the concrete. As the structure moves during settling or due to expansive soils, the sealant barrier material maintains a barrier impenetrable by termites and other insects.
Particulate termite barriers are widely used around the Pacific Basin. Developed commercially by University of Hawaii scientist Minord Tamashiro in the 1980s. However, particle barriers only recently became commercially available in the mainland United States. The principle behind particle barriers has been well researched by Ebeling and Pence (1957),[2] Su et al. (1991),[3] Su and Scheffrahn (1992),[4] Yates et al. (2003), and Keefer et al. (2013).[5] Basaltic termite particle barriers are used in Hawaii, but hardly any place else, because basaltic rock comes from volcano activity, which only takes place in isolated areas of the world. Any hard mineral, such as granite which is used in Australia, will work as a termite barrier if it has the requisite size and shape properties.
Research with particle barriers began at Texas A&M University in 2003. Various particle characteristics were evaluated, including size, angularity, and interstitial space between particles.[5] This material can be installed around the exposed perimeter of a home or structure in a wedge formation that measures 4 inches across and 5 inches down, directly against the foundation. Aggregate barriers have also shown success when installed in bath traps or slab leave-outs. During construction and after the foundation is poured, cardboard and other debris is removed from bath trap areas and the particle barrier is installed. Application of this material protects the structure from termite intrusion in a vulnerable entry point.
One problem with particle barriers is that there are erroneous references on the Web to the use of particle barriers to stop termites. One source says “use a sand barrier”. Another says that “16 grit sand is acceptable”. Although this loose specification is appreciated by some building contractors who can purchase “sand” or “16 grit sand” inexpensively at lumberyards and other outlets, it has the effect of damaging the credibility of particle barriers as a termite protection method. All of the research listed above, which took place at universities of California-Berkeley (1956), Hawaii (1982 – 2003), Florida (1992), and Texas A&M (2003 – 2013)pointed to sizes between 8 and 14 as being most effective.
Fortunately, there’s a lot people can do to prevent termite infestation. The process begins even before a builder starts to work on a house. Professional pest-control companies can treat the ground at the building site with a substance that kills or repels termites. This treatment usually offers protection against termites for at least five years. Builders can also construct houses in a manner that deters termites from entering. This basically involves making sure wood doesn’t come into direct contact with soil. Other techniques include placing a moisture barrier under basements to help keep the area dry and removing piles of soil from under porches. A termite inspection is usually part of the home-buying process, which reduces your likelihood of buying a home that is already infested.
These steps don’t guarantee that a home will never experience an infestation. Next, we’ll explore how to detect the presence of termites.
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