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As a negotiating tool designed to elbow aside the six other bidders on my previous house, the successful buyers chose to forgo such standards as a home inspection or radon testing.

They did not, however, sign off on a termite inspection, and no wonder. Just about everyone who owns a house has had to deal with termites and the damage that they cause, or know people who have.

Fortunately, the house passed muster, as did the house I recently bought, which, because it sold twice in six months, had two termite inspections.

Good thing, too, because there had been severe termite damage 14 years before, requiring substantial sill replacement.

Whether or not you are selling your house, you need to consider how termites can cause damage and how to prevent it. You need to know the telltale signs of infestation, and when to call a termite company to help you out.

First, the obvious signs of termite infestation include pencil-thin mud tubes extending over the inside and outside surfaces of foundation walls, piers, sills and joists; the presence of winged (swarmer) termites or their shed wings on windowsills and along the edges of floors; and damaged wood hollowed out along the grain and lined with bits of mud or soil.

But since 80 percent of the wood in your house is not exposed, a termite inspector possesses the tools that allow him to literally see in the dark.

One of these tools is a moisture meter, which can reveal elevated moisture content behind walls. The moisture can indicate a plumbing leak, or water from a sprinkler system, or from precipitation from a roof leak.

These all contribute to conditions conducive to infestation by termites, because subterranean termites can use the moisture for survival.

In these instances, an opening may need to be made in the wall to determine if the moisture is simply from some leak, or from an actual termite infestation. The inspector also will use a flashlight, probes and powers of observation to determine the presence of an infestation. It will require inspecting inside the structure, outside the structure, beneath the structure if there is a pier-and-beam foundation, and in the attic.

A new tool called a Tertramac can detect the movement of termites or other insects inside a wall. Some inspectors have also used the sensitivity of dogs' noses, with appropriate training, to detect termites in a structure.

During an inspection, areas checked include the subfloor and roof space, interior and exterior, and the site itself (trees and stumps within several feet of the house).

Termites usually travel inside the timber, forming moist galleries that swell the wood and create a wrinkled surface on the door frame. Damaged timbers are often paper-thin.

Termite infestation requires wood from a structure to come directly in contact with the soil. What home builders have started doing is constructing termite barriers to prevent such contact.

These barriers are either made of crushed stone or stainless-steel mesh. Termites use their jaws rather than their legs to move forward. Studies have shown that termites are unable to move particles larger than about 1 millimeter in diameter. As particle size increases, so does the size of the space between the particles.

Particles about 3 millimeters and larger provide spaces large enough for termites to crawl through. Therefore, coarse sand particles -- which range from 1 to 3 millimeters -- can be used as a barrier around the foundation of a house to protect against subterranean termites.

For the last 50 years, chemicals called termiticides have been used to control termite infestations. A complete barrier treatment may require hundreds of gallons of termiticide solution. The water-based solution is injected three to five feet into the ground alongside the foundation, beneath concrete slabs (basement and garage floors, patios, sidewalks, and driveways), and within foundation walls.

Pest-control operators use several different termiticides. All are safe and effective when used carefully according to label directions and will remain effective in the soil for five to 10 years.

An alternative is termite-baiting, which consists of a palatable and acceptable food material combined with a very slow-acting toxic substance.

Here are a few ways to eliminate the conditions that will encourage termites:

Look for conditions such as wood touching the ground or siding that traps moisture and correct the problem.

  • Remove tree stumps from around the house.
  • Fix leaky plumbing or drainage under the house.
  • Stack firewood off the ground and away from your house.
  • Don't let outside faucets drip onto the ground.
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