PROTECTING YOUR HOME AGAINST TERMITES
By Mike Potter, Extension Entomologist
- Homeowners can reduce the risk of termite
attack by following these suggestions.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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
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 specialist eye.
ALWAYS READ AND FOLLOW LABEL
DIRECTIONS FOR SAFE USE OF ANY PESTICIDE!