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NEW CONSTRUCTION TERMITE WORK – PART 2

The second in a two-part series by Dr Don Ewart examining the effect of the revised National Construction Code on termite-proofing work.

With the nearing end of the National Construction Code 2016 (NCC) grace period, which still permitted works to the old AS 3660.1-2000, Dr Don Ewart reviews the how the NCC impacts on termite work. In this issue, the second part of this article focuses on how the systems can be fitted together to create an integrated termite management system.

Rule number two for profitable pre-construction termite work: Think in four dimensions. Be aware of how things fit together, especially at the perimeter but don’t forget to consider time.

The NCC is concerned with risk management. In their list of 15 expected risks that have to be managed, termites come in at #15, with earthquakes (#4) and snow (#5) taking precedence. Termites are an afterthought, and it shows. That’s how we end up with an NCC that has no grandfather clause for existing systems.

Concepts

Australian Standard AS 3660.1-2014 is a guide to “whole-of- house” termite management and it sets out ways to block paths that termites might take to get in without being seen.

Words are important; just ask your insurance company. Don’t over state what is being achieved. You are not ‘preventing’ termites, you are not ‘eradicating risk’, you’re not even keeping termites out. Termites can always fly in. That new paving, deck, mulch or garden can negate perimeter defences. The plumber that moves floor drains after the concrete pour, the expansion bolts cracking a slab edge, the forgotten form work, and the unexpected pour interruption, can all defeat your work. Pest risk management is a process, not an installation event – every building requires inspection.

Suspended floors win

The easiest buildings to manage are those with suspended floors and good access underneath. For inspection access you want 400mm or better and in AS 3660.1-2014, that also means 400mm under any suspended ducts or services.

The horrible provision that the clearance can be reduced to only 150mm at the top of a 2m slope, still survives, but should be resisted. With a full 400mm you can rely on inspections rather than termiticide to soil, but if there is any spot of restricted access, even the allowed 150 slope, you should require more frequent inspections for your warranty.

Do one better?

Of course you can still spray under a suspended floor or a slab or whatever. There is nothing stopping works in excess of the Standard’s minimum, other than the customers’ willingness to pay. You might for example, apply collars and perimeter sheet as well as a traditional spray.

There is a provision in AS 3660.1-2014 at Clause 7.1.1 that where you are applying termiticide to what will become a concealed and inaccessible area, you then need to supply a reticulation system to provide for replenishment. You can still spray it at construction, but if the sprayed soil surface is to be no longer exposed, the pipes are needed. Sure you can drill concrete later, but if you know it is going down, not to supply pipe for future use is simply, not to comply.

Concrete concerns: collars

Most floor slabs have penetrating pipes that are fitted with collars. There are many brands of collar to choose from and many ways to put them in. They can be embedded or go in under or over the slab (Figure 1).

Embedded collars must not be close enough to any reo to cause cracking (at least 50mm from any bar and 40mm down from the top). If your collar is set too high, a circular crack may appear, indicating failure. The collar’s flange must have contact with the concrete of at least 15mm and must extend at least 20mm along the pipe. 15mm is a lot less than many current products and you can look forward to cheaper collars.

Figure 1: Collars can be placed in various locations

Collars cast in at the base need to have a vertical 15mm flange. Collars can be put onto the top of the slab where they are adhered to the concrete using a ‘termite-resistant adhesive or filler in accordance with AS 3660.3’. If installing after a pour, you can chip the concrete and install the collar as a puddle flange. See Figure 1. Most people use hard plastic collars, but a sheet material flange is fine, just so long as your installation achieves the minimum dimensions. It is no longer enough to simply wrap the pipe.

Collars are mostly designed to go around rigid PVC plumbing pipes; pipes which are themselves termite resistant. There’s not a lot of point putting a collar on a soft plastic pipe, or flexible duct, as the termites can excavate the soft plastic with relative ease. Where a builder uses ducts so that services may be run in later you must take steps to manage the risk of termites simply walking in via the duct. Always mark these as a limitation and if you can’t block entry, make sure there’s a port so the inside end can be inspected.

Concrete concerns: joints

Where slabs are jointed or poured against each other can be a hassle and is a common point of installation failure. To install to these locations you need to know if the chosen product can safely handle the expected movement. Joints may move 25mm or more. A gunned-in sealant is likely to simply rip off one or both slab faces. The side of a slab can be chalky where bleed water has been retained, reducing adhesion. Similarly a vertically placed sheet may not continue to make adequate contact as the concrete moves back. The requirements are set out in the Standard at Clause 5.3.7 and are based on a minimum of 15mm movement capacity.

To install integrated systems to buildings, it is important to think in three dimensions and to make sure that everything fits together to block any point of concealed access. A good example of that is where a slab joint runs to the exterior of the building where it must be effectively interfaced with the perimeter detail. Further, you must often add another dimension to your thinking and consider how your detail will perform over time.

Still need a notice

The ‘durable notice’ provisions have been changed. Since the NCC rules, the durable notice mention was taken out of AS 3660.1. That doesn’t mean you don’t need to supply one, just that the requirement is now at NCC Vol 2, Clause 3.1.3.4. Further, Queensland have dropped their specification for at least two notices. Again, that doesn’t mean you can’t put more in. Personally, I’m in favour of having at least two, including one to the inside face of a kitchen or hallway cabinet. The durable notice still has to name the termite management system(s) used, the date of installation and where a chemical is used (which includes sheet products such as Homeguard), also detail its life expectancy as listed product label and the recommendations for future inspections. It is a great opportunity to inform, manage risk, and provide gentle advertising.

Choosing systems

The choice of what to install is often driven by customer demand and supplier availability. Some of the more prominent system suppliers are loathed to take on new, or small volume installers when they already have the market well covered. That leaves the lesser-known systems, which may, in the end, be just as successful. Make sure that whatever you use comes with certification that it meets either (1) AS 3660.1-2014 through successful testing to AS 3660.3-2014 or (2) has a current CodeMark certificate and that the details you’re using are covered in the product manual version quoted in the CodeMark certificate. Unfortunately, that means that many previous used solutions, such as generic termiticides with an APVMA me-too label will not meet the building code requirements after 30 April (but they could be used for subsequent works, where AS 3660.2 applies).

For your expansion into reticulation, it is good to keep in mind that a repellent termiticide is best restricted to use where you are certain of achieving a complete and even application. Where there is doubt, a non-repellent may prove a superior choice. Be sure to provide do-not-disturb information to your eventual customer, the building occupier, such as advice not to plant gardens into the poisoned soil, particularly if you have used a chemical such as imidacloprid, which is readily picked up and transported by plant roots.

Final thoughts

If you are using soil chemical, make sure that you understand the NCC requirement at Volume 2, Figure 3.2.2.3 for the plastic to remain at the slab edge. Ask your suppliers for product certification to AS 3660.3– 2014. Check your paperwork and make certain that whatever you do (1) meets the NCC and (2) is actually covered by your insurance policy.

Don Ewart

*Dr Don Ewart, a doctor of termites, Chairs the Standards Australia Committee. He is a consultant to industry and pest managers, teaches pest management for Melbourne Polytechnic and can be found at drdons.net and contacted at don.ewart@tiprm.com

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