General

Insects are not just a nuisance; some are also a serious threat to building durability. The following types of insects are known to damage wooden materials in homes and in other structures:

• Termites
• Carpenter ants
• Wood-boring beetles
• Carpenter bees

While all of the above insects can pose a threat to wood-framed homes, termites are the most prevalent and damaging insect. Therefore, most of this chapter addresses issues and practices related to the control and prevention of termite infestation. Some of the practices for repelling termites, such as eliminating hidden areas that termites can travel through undetected, are also relevant to carpenter ants. Carpenter ants and wood-boring beetles, like termites, can be treated chemically with insecticides. Carpenter bees can be deterred by plugging entrance holes that commonly occur on wood siding and soffits.

There are about 57 species of termites in the United States that can be placed into two groups: subterranean (ground inhabiting) and non-subterranean (wood inhabiting). Subterranean termites are the most common and are responsible for most termite damage to wood structures. Therefore, this chapter focuses on subterranean termites. If non-subterranean termites are present, special measures may be necessary to eliminate them. Fortunately, non-subterranean termites live in much smaller colonies and are much slower acting than subterranean termites.

One variety of the subterranean termite group is the Formosan termite, an Asian termite introduced to the United States following WWII. The Formosan termite is different from the native subterranean termite in that it has a much greater colony size and thus damages wood at a much faster rate. Estimates state that a colony of Formosan termites will consume nearly 1,000 pounds of wood per year, whereas other termite varieties will only eat a few pounds annually. Formosan termites are also more likely to survive in a building with minimal ground contact, even though they require a constant source of water like other subterranean termites. Formosan termites are expanding in range, and are currently found in the Gulf Coast states and southern states along the Atlantic coast.

A termite hazard or probability map, shown in Figure7–1, is frequently used by building code authorities, designers, and builders to determine when certain termite prevention or control methods should be used. The building codes may vary in delineation of the termite probability zones based on local conditions. The inclusion and degree of termite control and prevention used in a building depends on the risk of termite infestation, as well as local experience. Talk to neighbors to determine where and when historical infestations have occurred.

In summary, termites like to eat wood and they don’t care if it’s in your home. In areas subject to termite infestation, at least one of the practices listed in Section 7.2 should be used.