Deltamethrin: the termiticide in Kordon treated sheets

Deltamethrin is a synthetic-pyrethroid termiticide. In Australian building work its headline use is not a sprayed soil treatment but a treated sheet: it is the active impregnated into the Kordon termite barrier made by Envu (formerly Bayer Environmental Science), where it kills termites on contact and acts as a repellent (verified 2026-05-26, Envu Kordon and NPIC). It is APVMA-registered and used as part of an AS 3660 termite management system.

What it is

Deltamethrin is a synthetic pyrethroid, a lab-made analogue of the natural pyrethrins found in chrysanthemum daisies, the same broad family as bifenthrin. It is one of the most potent and widely used pyrethroids worldwide, used against a long list of insects in agriculture and public health as well as in termite control.

Its mode of action is that of the pyrethroid family: it is a sodium-channel modulator (insecticide resistance group 3A) with contact and stomach action, disrupting the insect nervous system and giving a fast knockdown (verified 2026-05-26, NPIC). In termite terms that means a termite contacting a deltamethrin-treated surface is killed quickly, and the treated surface is also repellent, so termites tend to avoid it.

How it works in a termite barrier

The key thing for a builder is how deltamethrin is delivered. Bifenthrin and fipronil are most often applied as chemical soil treatments, sprayed or injected into the ground. Deltamethrin’s main residential role is different: it is built into a manufactured sheet.

In the Kordon system, deltamethrin is carried on a polyester webbing laminated between two UV-stable polyethylene sheets. The sheet is laid as a physical-plus-chemical barrier at penetrations, perimeters, and construction joints. A termite trying to breach the barrier meets both a physical membrane and a contact termiticide at once.

Because deltamethrin is a repellent contact active (like bifenthrin, and unlike the non-repellent fipronil), the barrier works by deterring and killing termites at the treated sheet rather than by letting them pass through and carry a dose back to the colony. As with any repellent system, the barrier has to be continuous and correctly lapped: termites probe for an untreated gap, so a missed penetration or an unsealed join is the weak point.

How it compares to bifenthrin and fipronil

The three actives a builder meets on termite work line up like this:

	Deltamethrin (Kordon)	Bifenthrin (Biflex, HomeGuard)	Fipronil (Termidor)
Chemical family	Synthetic pyrethroid	Synthetic pyrethroid	Phenylpyrazole
Usual form	Treated sheet (laminate)	Soil treatment or treated sheet	Soil treatment
Mode	Repellent, contact kill	Repellent, contact kill	Non-repellent, transfer effect
Barrier logic	Continuous sheet; a gap is the entry point	Continuous; a gap is the entry point	Termites pass through and pick up a lethal dose

Deltamethrin and bifenthrin are the same broad family and both work by deterrence and contact kill; fipronil is the odd one out, designed to be tunnelled through. None is simply “better”: the right system is the pest technician’s call for the site and the management plan. For the builder, the point is that a deltamethrin sheet, like any repellent barrier, lives or dies on being unbroken.

Where it fits in the build

Deltamethrin most commonly appears as the active in a treated-sheet termite barrier, installed during construction at the points termites would use to enter: pipe and conduit penetrations, the slab perimeter, and construction joints. It is one of several recognised barrier routes (physical barriers, treated sheets, stainless mesh, graded stone, chemical soil treatments); deltamethrin is the active behind the treated-sheet route.

It does not stand alone. The barrier works alongside the rest of the AS 3660 system, including the termite inspection zone, the exposed slab edge that keeps any bridging visible.

The NCC requirement behind it

Deltamethrin is used because the National Construction Code requires termite risk management. NCC 2022 Volume Two calls for a termite management system to protect the primary building elements of a Class 1 building in areas where termites are a known risk, and it names AS 3660.1 as the deemed-to-satisfy path (verified 2026-05-26, ABCB NCC 2022 Housing Provisions). A treated-sheet system carrying deltamethrin is one acceptable way to meet that obligation. The Code also requires a durable notice fixed in the building (commonly in the meter box or under the kitchen sink) recording the system installed, its date, and the inspection regime.

Compliance and who installs it

AS 3660 series. Termite management for new building work sits under AS 3660.1, and treated-sheet products are assessed under AS 3660.3. The recognised deltamethrin sheet systems are independently certified (Kordon, for example, carries CodeMark certification).
APVMA registration. Deltamethrin termiticide products are registered with the Australian Pesticides and Veterinary Medicines Authority (APVMA), the federal regulator. Using a product outside its registered label use is not compliant.
Accredited installation. Treated-sheet barriers are installed by accredited installers to the manufacturer’s system and the standard, and an installation certificate forms part of the building’s documentation.

For a builder

Coordinate the timing. A treated sheet goes in at specific points in the slab and penetration sequence; book the installer into the program rather than chasing them late.
Protect the barrier. Once a sheet is laid, do not cut, puncture, or build through it without the installer reinstating it. A breached sheet is a breached barrier.
Keep the paperwork. The installer’s certificate (system, active, area, date) is part of the compliance record and the durable-notice obligations.
Brief the client on inspections. A certified sheet system is long-lived, but the homeowner still needs ongoing annual inspections; the barrier deters and kills, it does not remove the need to look.

References

Envu, How to control termites with Kordon (manufacturer, deltamethrin as the Kordon active, contact kill and repellent; verified 2026-05-26).
National Pesticide Information Center, Deltamethrin General Fact Sheet (synthetic pyrethroid, mode of action; verified 2026-05-26).
Australian Building Codes Board, NCC 2022 Housing Provisions (termite management requirement and AS 3660.1 path; verified 2026-05-26).