Myth Conceptions

Conventional wisdom has conditioned termite controllers to target the soil around and under the structure for treatment. That’s the natural environment in which enough cellulose in tree parts, along with water and space, favors the growth of huge colonies. In my "Myth Conceptions" columns of March 1989, January, 1990 and February, 1990, I explained how anomalies in construction, through design and through negligence, have given the opportunistic termite a suitable environment in buildings completely independent of soil contact. In last month’s column I complained that the termite control industry was in essence restricted to the philosophy of a soil barrier as the exclusive strategy in the control of subterranean termites. This was because research that supported the termiticide label was exclusively devoted to pre-construction treatment for prevention of termites rather than treatment of infested homes. Post construction termite treatment has always been done essentially using directions for pretreating.

Yes, provision was made to drill and treat infested wood members. The Approved Reference Procedures for Subterranean Termite Control states, "The treatment of wooden members of a structure in place has limited value in termite control. This method should be considered supplementary to mechanical alteration and soil treating… The injection of these insecticides into channels and voids of termite-infested wood kills workers or winged reproductive forms which may be present in the channels and prevents swarms after treatment…"

This is sound advice, in my opinion, in he majority of situations. I reflects the conventional strategy that is built around existing labels.

In recent months, PCOs have become more aware of "high riser" termites. These are infestations above grade which have no contact with the soil. Clearly, in some cases, treatment of voids in the wood is not a "supplementary" treatment. It’s the soil treatment that may be supplementary, although certainly necessary to prevent future attacks in conventional pathways.

Friendly insulation. In recent months, I’ve discussed some "building boners" by builders and architects which favor termite attack of structures. Industry consultant Tom Parker told me of another anomaly in construction which figured frequently in the serious termite cases which he investigated.

These have to do with the ubiquitous use of the building material Celotex, or several of its generic equivalents. This I a composition board made of sugar cane fiber (bagasse) and is widely used for insulation in buildings. Some of these fiberboard sheathing products were treated with an asphaltic material for water repellency, or they were coated with dye to imitate asphalt; sometimes they were left uncolored (tan). Some of the manufacturers of fiberboards have added wood particles to the bagasse, which may be why this element of construction is so delectable to termites. Bob Wright, veteran PCO of Ft. Lauderdale, Fla., believes that a pure bagasse is not particularly attractive to termites.

Asphaltic material is no longer used in newer fiberboard product because of environmental and legal concerns. I don’t believe the asphalic component ever deterred termites, having seen roof paper rolls in storage eaten by subterranean termites.

Because of its cost efficiency, fiberboard sheathing was a favorite element of construction. But it was often used in questionable ways, such as in areas prone to becoming wet. This cellulose-rich substrate is particularly desirable to termites.

Entomologist Parker finds it used frequently in structures as insulation behind brick and stone veneer. However, if the vapor barrier is faulty (as it frequently is), the fiberboard may become moist enough to keep termites from the necessity of returning to the soil. He also found it used as underlayment under bathtubs and behind shower stalls, both high-moisture areas.

He even found a fiberboard sheet being cut up into 4-inch strips to use as expansion joints, just to save a few pennies. This poses a special hazard, especially when paneling hides the jointure, which is exacerbated when the fiberboard is used for insulation panels on the basement walls.

Buildings with radiant heat are particularly susceptible to termite proliferation according to Parker. Fiberboards are sometimes used for insulation under a heated slab. To compound the problem, builders use and leave the stakes set to position the hot water pipes embedded in or under the slab. In large housing developments, he found that termites traveled between the polyseal and the slab, thus avoiding treated soil. The wood stakes always extended into untreated soil and were not removed. The heated slabs were responsible for termite population explosions, having year round heat, food and water.

Additional problem areas. Another trouble spot in crawl spaces are the make-shift air conditioning and hot/cold air ducts which are made of fiberboard. This is covered with aluminum foil-covered synthetic foamboard. The foil is easily nicked, and the termites can reach the fiberboard as well as wood members nearby, according to observations made by Greg Baumann of The Wyomissing Group, S.E.C.U.R.E., Reading, PA.

At even worse termite trap was described by Eric Smith, technical director, Dobson Bros. Exterminating Co., Lynchburg, Va. Thousands of ranch homes are heated with paper mache and/or cardboard formed heat ducts which are embedded within and below the slab in perimeter or spider configurations. His advice: "Plug up old ducts and install a new above slab system."

This, of course, is not a "high riser" problem. Conventional treatment preceded by the "jugular strategy" could control such infestations. But these problems are challenges that call for a highly skilled and imaginative technician.

High risers. The use of fiberboards in attics and upper floor bathrooms is a boon to ‘high riser’ subterranean termites. Once they reach these heights, they will proliferate without soil contact if the fiberboard has external moisture exposure. Such sources would come from such conditions as condensation faults because of improperly placed vapor barriers, dripping from condensation caused by cold water in a water closet in a humid bathroom and other common aberrations. Such moisture will keep the fiberboard, plywood or particleboard underlayment wet enough year round.

Before synthetic insulating materials were on the market, fiberboard or particleboards were most frequently used as an insulating component of the roof assembly. Inevitably, leaks develop in a flat roof.

One of the most widely used insulation materials is ground paper particles which are blown into attics and between studs. I checked an old architectural manual for construction data on other insulating materials. These, of course, are the materials we are dealing with in older structures infested with termites. Besides the fiberboard sheathing, I found such termite delicacies as corkboards to 2 inches thick and powdered cork. There was also plastic-coated plywood or hardboard.

In addition, there was also "wallboard," which is any of several structural boards of sheets of various materials such as gypsum plaster encased in paper or compressed wood fibers and chips used in construction as a substitute for plaster or wood panels. Particleboards are a relatively new product in building construction which has been very attractive to builders and to bargain furniture manufacturers, and is sometimes attacked by subterranean termites. Wood lathe base for plaster in older homes is also attacked.

Sometimes, non-cellulosic insulating materials such s rock wool, mineral wool, glass wool, vermiculite and perlite are blown into cavities for insulation value. However, they lose their value when wet. While these materials are not eaten by termites, their capacity to hold water increases the moisture content of the wood members that contain the blown insulation. High riser termites can then flourish in these wet studs or rafters.

Most modern buildings now have non-cellulose insulation made of plastic materials, such as Styrofoam, and expanded rigid polystyrene plastic. Styrofoam and similar plastic materials can easily be penetrated by termites for passage or y other pests for habitat. Frequently, the plastic insulation board that is placed against the foundation wall in crawl spaces serves as a convenient cover for easy passage from soil to wood. The ell-tale mud tubes are hidden.

In some buildings, another plastic insulator, formaldehyde foam, was retrofitted between studs or rafters. While now legally restricted, it also restricts termite activity, being antagonistic to insect life.

These changes in structural ecology caused by architects and builders are indeed profound. They affect the strategies and concepts of pest control significantly. We must be prepared to change our "Myth Conception" to new realities in termite control.

___ Harry Katz

The author is a contributing editor to PCT magazine. His most recent columns have dealt with termite problems caused by modern construction practices.