What are Termite Pre-Treatments?
"Pre-treatment" is a term for termiticide that is applied to the soil. This page relates principally to the continental United States as other parts of the world (including Hawaii) often have less toxic approaches to termite management. It refers to the use of toxins applied to the soil as a means of blocking concealed access to a structure by subterranean termites (as opposed to drywood termites).
Most new structures in United States are treated against termites during the initial construction process. These applications of poisons into the soil under and around building being constructed are what is meant by "termite treatments" and in the trade these are commonly referred to as pre-treatments or “pre-treats.” Physical barriers and proper construction are other methods of preventing termite infestation.
A termite pre-treat is intended to create a barrier of termiticide between termites found in the soil and wooden structures of the building. To provide a consistent barrier, termiticide labels (the registered labels applied to the retail containers) recommend the volume, concentration and areas for the application of the termiticide. In effect, large volumes of emulsion are needed to effectively fill the soil around the foundation walls, support piers and the soil to be covered with concrete slabs. It is a violation of US Federal Pesticide Laws and most State laws to apply termiticides at concentrations and/or volumes less than indicated rate prescribed by the brand label, however, others following the US FIFRA Act allow for a lower dosage to be applied where the applicator considers this appropriate.
The cost of termite pre-treatments have risen significantly over the last decade due to a move towards newer, more complex chemicals and the costs of labor, insurance, and fuel. Treating a 140 sq m (1,500 sq ft) home can cost US$200 to US$600 in chemical costs alone. Cost can also differ depending on the type of construction materials, soil compaction and foundation.
Types of Pre-Treatments
Poured Slab – This is for a building that sits flat on the ground, typically on a concrete slab. A termite technician will measure the area (usually from the plan) which is to be covered by the structure (with concrete, including masonry blocks and/or support columns, if applicable). Ideally, the termiticide will be applied to the sub-floor before any concrete is poured. Most termiticide labels require the application of one gallon of dilute termiticide per 10 square feet of slab area (around 5 litres per sq m).
Americans don't seem to have generally caught on to the use the concrete slab as part of their barrier system. Termites cannot chew through a properly built, modern, reinforced and cured concrete slab. However, in spite of this, if the sub-slab soil is not treated prior to the concrete pouring, the slab is then drilled, following the label directions, adjacent to the foundation/ perimeter, support columns and other critical areas, and then the termiticide emulsion is pumped into the soil with a laterally-dispersing hollow rod. The label-specified volumes and concentrations vary across the brands, but usually require 2-4 gallons per 10 liner feet (about 2 to 5 litres per metre).
Crawlspace Foundations - A suspended floor (often timber) is built with a sub-floor air gap. In the USA, this gap is typically tall enough to allow a technician to crawl beneath the floor, hence the term 'crawl space'. Treating a crawlspace involves the placement of a chemical to the soil so as to provide as close as possible (to a but never quite) continuous chemical barrier on both sides of the foundation. The outside perimeter of the foundation is treated at the footer level. The application rate is usually 4 gallons per 10 linear feet (about 5 litres per metre). If the foundation consist of hollow blocks, an additional 2 gallons per 10 linear feet is often required. Other structural elements of the building must also receive treatment in the soil surrounding them - support columns, porches, plumbing penetrations and other critical areas. This rather haphazard approach is much less certain than the highly detailed application specifications used in Australia's Standard 3660.1
Basement Foundations -
Americans seem to like building basements of hollow concrete blocks. These are an ideal way to attract termites as the hollows allow for easy termite access and help to store water for their use. Treating the soil around these structures is difficult, but much easier during construction than after. The termite pre-treat of a basement seeks to create a continuous chemical barrier on both sides of the foundation. The treatment guidelines are very close to the “crawlspace” requirements, but extra drilling of masonry voids near the footer is usually done. See. Ideally, a basement would be made from void-free solid poured concrete and the termite entry points then reduced to just the joints (which can be blocked with a termite-resistant sealant), however this is not yet popular in the USA. Trying to create a barrier in hollow masonry by drilling into it and flooding the voids is at best wishful thinking. The termiticides will not fully penetrate the mortar and many entry paths usually remain. Any exclusion of the termites is usually attributable to the termiticide placed around the exterior walls, however even here, the settling of loose fill can create voids through which termites can easily pass.
Is Termite Pre-treatment Worth The Cost?
Competently treated structures are expected to resist termites for a much longer period of time than untreated or post-construction treated structures. However, the treatments are not permanent—if they were they would not be allowed—so it is always preferable to rely on physical barriers as the primary protection. While some chemicals may be still adequately toxic after 10 years under a slab, most will be significantly degraded and the pest managers typically suggest re-application to accessible areas by 5 years after construction. Some building features that are frequently tested by termites, such as where plumbing penetrates slabs and any buried masonry walls, are not accessible once construction is completed unless significant and damaging works are undertaken. The costs of treating at construction are typically 50-70 percent less than for a post-construction job, but more importantly it is only during construction that all the potential risk areas can be properly identified.
Termite Pre-treatments and New Additions/Structures
All new constructions in areas where subterranean termites are a risk should have barriers installed. New additions to your home, such as - garage and sunrooms - also require barriers to termites. Even if the home was poisoned before, termites can bypass the original termiticide and attack the new structure.
Swimming pools can be damaged by termites if the walls are made of wood that have not been rated for wood-to-ground contact. Termites will chew through most soft plastics, so swimming pool liners are readily damaged, particularly if they are placed directly over a food source such as peat. Modern plastic water pipes and tanks are similarly at risk but metal and unplasticised PVC pipes are rarely affected.
Termite Pre-treatment Recommendations
1) Make sure the company performing the work is competent, licensed, insured and bonded.
2) The builder and termite manager should maintain communication before and during the construction of the foundation and have a mutual understanding of the completed structure so that all additions and finished soil levels are properly covered. All parties need adequate notice regarding changes in structural elements and soil conditions.
3) Be aware of soil conditions at the job site. The termiticide emulsion is applied to soak into the voids in the soil and typically (but not always) is expected to bond to organic carbon (think dead things) and so avoid washing away. It is much easier to apply chemical to sand (big voids) but bonding is poor while fine clays offer better bonding but fewer gaps for the emulsion to penetrate. Like stone, some clays are effectively untreatable unless broken up. If the soil is saturated with water or if it is too cold, it will be impossible to apply the chemical at the required label rate. Liquid termiticide labels prohibit the application of the product if soils are frozen or saturated.
- Michigan State University
- "National Pest Management Association (1)". Retrieved 2008-02-12.
- "North Carolina State University: Termite Guidelines (2)". Retrieved 2008-02-20.
- "Michigan State University: Management of Wood-Destroying Pests (3)". Retrieved 2008-03-15.