Termite treatments & prevention tips

William Kibbel III, The Home Inspector

Dear Home Inspector: The 100-year-old home we're purchasing was treated for subterranean termites four years ago, according to the seller. How can we be sure the treatment was effective? Does the treatment always kill all of the termites? After we purchase the house, should we have it treated again?

Pest control contractors have a saying: There are two kinds of homes: those that have termites and those that will. It would be unusual if a 100-year-old home didn't have some previous infestation of some type of wood-destroying insect. Effective and early treatment can prevent significant damage. Dealing with subterranean termites is tricky, since the ones that cause the damage are experts at staying concealed while they devour critical parts of old homes.

The area in the white rectangle is a shelter tube, the most common sign of termite infestation. Termites make these earth-colored tubes as protected runways from the ground to the wood they feed on.

Wood that has been infested may look rotten.

You should first contact the exterminator who performed the previous treatment. Hopefully, a detailed report, including a diagram of the prior damage and activity, was prepared prior to treatment.

Next, a pre-purchase, wood-destroying insect inspection should be performed. The report and diagram from the previous treatment should be compared to current conditions. Any new signs of damage, or other evidence of re-infestation, certainly warrant additional treatment. Licensed exterminators will not apply chemicals unless there is an active infestation.

Until recently, the only method of treatment was to inject a chemical into the ground, and sometimes into the foundation. This creates a coating that the termites have to pass through as they enter or exit the structure. Chlordane was a common termiticide used prior to 1988 and is thought by industry experts to provide protection for 30 to 40 years. More recent products have a much shorter estimated time of protection, some as little as 5 years.

The newest treatment is called a baiting system. It consists of hollow perforated plastic spikes that are inserted into the ground around the home. Bait (cellulose) is placed inside the spikes and then they are monitored. Once there is a hit the inert bait is switched with termiticide. Many exterminators are skeptical that this new method is completely effective. Some use the system for monitoring only, or in tandem with the injected chemical.

After a thorough pre-purchase evaluation of the home, you should establish a pest management plan that involves both the homeowner and an experienced, licensed exterminator. Service contracts that include annual inspections are usually available. Some offer a warranty for the cost of treating future infestations.

ground contact
Moisture, vegetation, and soil around this wooden window frame are in invitation for termites to come in and dine. This homeowner could less the the chance of infestation by following some of the steps listed below.

Here are some things that any homeowner can do to eliminate common conditions that invite termites inside for a buffet:


  • Remove any vegetation, mulch or soil that covers the foundation completely or contacts any wood surfaces (siding, trim, basement window frames, etc.)
  • Replace wood that must contact the soil (deck supports, lattice, steps, fences retaining walls) with treated materials.
  • Keep stored firewood or other lumber well away from the structure.

Termites need moisture to survive. This is why they need to have access to the ground unless there is a perpetual source of moisture within the home. Be sure grading slopes away from the foundation. In addition:

  • Maintain gutters regularly and extend downspouts.
  • Take steps to reduce moisture in crawlspaces.
  • Immediately repair any leaking roofs, flashings, pipes or plumbing fixtures.


The above strategies are also recommended for the few old homes that haven't had an infestation -- yet.

About the Author
William Kibbel III is a home inspector and restoration consultant specializing in historic residential and commercial buildings. He is vice president of Tri-County Inspection Company, serving Southeastern Pennsylvania and Central New Jersey.

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