PROTECTING YOUR HOME AGAINST TERMITES

By Mike Potter, Extension Entomologist

University of Kentucky College of Agriculture

R. Bessin, University of Kentucky Entomology

The Entomology Department often receives calls from people wanting to know what can be done to protect their home from termites -- or if a certain practice or condition is likely to cause termite problems.

Homeowners can reduce the risk of termite attack by following these suggestions.

1. Eliminate wood contact with the ground. Many termite infestations result from structural wood being in direct contact with the soil. Earth-to-wood contact provides termites with simultaneous access to food, moisture, and shelter, as well as direct, hidden entry into the structure. Wood siding, porch steps, latticework, door or window frames, posts and similar wood elements should be at least six inches above ground level. Eliminating wood-to-soil contact may require regrading or pulling soil or mulch back from the foundation, cutting the bottom off of wood latticework, or supporting steps or posts on a concrete base. Posts or stairs that are embedded in concrete are also vulnerable to termites since they usually extend all the way through the concrete to the soil. Contrary to popular belief, wood which has been pressure treated is not immune to termite attack; termites will enter pressure-treated wood through cut ends and cracks, and will also build tunnels over the surface.
2. Don't allow moisture to accumulate near the foundation. Termites are attracted to moisture and are more likely to enter a structure if the soil next to the foundation is consistently moist. Water should be diverted away from the foundation with properly functioning gutters, downspouts and splashblocks. Leaking faucets, water pipes and air conditioning units should be repaired, and the ground next to the foundation should be sloped (graded) so that surface water drains away from the building. Homes with poor drainage may need to have tiles or drains installed. Lawn sprinklers and irrigation systems should be adjusted to minimize water puddling near the foundation.
3. Reduce humidity in crawl spaces by providing adequate ventilation. Most building codes call for 1 square foot of vent opening per 150 square feet of crawlspace area. For crawlspaces equipped with a polyethylene vapor barrier, the total vent area often can be reduced to 1 square foot per 300 to 500 square feet of crawlspace area. One vent should be within 3 feet of each exterior corner of the building. Shrubs, vines and other vegetation should not be allowed to grow over the vents since this will inhibit cross-ventilation. Moisture in crawl spaces can further be reduced by installing 4-6 ml polyethylene sheeting over about 75 percent of the soil surface.
4. Never store firewood, lumber or other wood debris against the foundation or inside the crawl space. These materials attract termites and provide a source of food. When stacked against the foundation they offer a hidden path of entry into the structure and allow termites to bypass any termiticide soil barrier which is present. Vines, trellises, and other dense plant material touching the house should also be avoided. Dead stumps and tree roots around and beneath the building should be removed (where practical), along with old form boards and grade stakes left in place after the building was constructed.
5. Use decorative wood chips and mulch sparingly, especially if you have other conditions conducive to termite problems. Any cellulose-containing materials, including mulch, can attract termites. Termites are especially drawn by the moisture-holding properties of the mulch. Where mulch is used, it should never be allowed to contact wood siding or framing of doors or windows. Crushed stone or pea gravel, though often considered less cosmetically appealing, is less attractive to termites. These materials also will reduce problems with other pests such as millipedes, pillbugs,earwigs and crickets.
6. Consider having the structure treated by a professional pest control firm. Although the measures outlined above will help make the house less attractive to termites, the best way to prevent infestation is to treat the soil around and beneath the building with a termiticide. Buildings have many natural openings through which termites can enter -- most of which are hidden. Soil treatment makes the ground around the foundation repellent and/or toxic to termites so that they will not penetrate through the treated layer. Termite-specific baits have also been developed recently, with the intent of eliminating termite foraging in the vicinity of the structure (See Entfact 639, Termite Baits: A Guide for Homeowners).

   Preventively treating a home for termites is a reasonable investment, especially if the structure has had no prior history of treatment. If the building was previously treated by a pest control firm, it's a good idea to maintain the warranty by paying the annual renewal fee. Should termites reinfest the building (which can happen even if the initial treatment was performed correctly), the company will return and retreat the affected area at no additional charge.

Whether or not a person chooses to have their home treated, they should know the signs of termite infestation:

• pencil-thin mud tubes extending over the inside and outside surfaces of foundation walls, piers, sills, joists, etc.
• the presence of winged (swarmer) termites, or their shed wings on window sills and along the edges of floors.
• damaged wood hollowed out along the grain and lined with bits of mud or soil.

Detecting hidden termite infestation requires a trained eye. Most pest control firms perform inspections free of charge and will also alert the homeowner to any conditions they uncover which are conducive to termite attack.

CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication.

Of course, ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY PESTICIDE!

Issued: 2/93
Revised: 11/97