Subterranean termites are very common in mild climates. About 40% of the homes I inspect that are at least 40 years old show some signs of termite invasion. The invasion occurs after termites swarm from a mature colony. Scores of mating pairs fly off in search of new nesting sites. A pair will borough next to a large supply of dead wood that they spot from the air. Eventually, the main nest will be fifteen to twenty feet down in the ground. The pair sheds their wings, and the queen becomes an egg laying machine, producing thousands of soldiers and workers in her lifetime. The workers will create tunnels for ventilation and as pathways to dead wood, their food source. Some species of termites can survive above ground, but subterranean termites, common to the southeast half of the U.S., need to return to the soil for moisture. They do not nest in the dead wood. They take it back to their nest in the ground to culture a fungus, which is their actual food.
Understanding how termites live and what they need helps develop an understanding of how to kill them and how to discourage a mated pair from nesting nearby. Obviously, removing firewood, tree stumps, and woody mulch from around the house will discourage termites from establishing a colony. Even a tree stump several feet away will attract termites. They will eat along the roots until they reach the house. Since they need moisture, they will be attracted to moist wood more than dry wood. Since they need a soil path at all times, keep soil away from the top of the foundation, where the wood inside the house starts. Once inside the house, termites can work for years undetected. A colony will grow in size, and can do extensive damage. Most often, termites stay in horizontal members of wood such as floor joists, flooring and baseboards. However, they can travel vertically along wall studs as high as the attic.
If caught early enough, infested areas might not need repair. Sometimes, damage is far advanced. I have seen some joists and wood columns so damaged that I was able to thrust my screw driver completely through the piece of wood. If damage is extensive along a horizontal joist, then bolting or screwing a new piece of wood to one side of the joist may suffice to strengthen the weakened board. Another easy remedy is to add columns to support the damaged area. Both remedies are relatively inexpensive.
Pest control companies offer inspections for about $50. If your house hasnít been inspected for five years or longer, itís a good idea. Termites can be easily poisoned, but such treatment should only be applied by a licensed pest control professional. There are three basic types of treatment: a) injecting poison through holes drilled every 18 to 20 inches around the perimeter of the basement slab or into the foundation wall if the wall is made of concrete block, b) injecting poison deeply into the soil around the house, or c) installing poisonous bait in plastic tubes into the ground around the house. The injected poison establishes a barrier that the termites must pass through when they return to the nest. The bait method works when termites find the bait and start carrying it back to the nest. Treatment costs depend on the distance around the house. Treatment companies offer one year guarantees on their work. They also offer inexpensive annual policies when the initial guarantee expires. Itís a good investment.
John R. Berry, PE
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