Termite expert Dr Don Ewart explains the ins and outs of using a reticulation system to prevent termite ingress.
The Building Code, as it is modified for Queensland, requires a 50-year design life for all pre-construction termite management systems. All the system providers were claiming that their products could last that long.
The Standards Committee decided to include a national 50 year target in AS 3660.1–2014. The Building Codes Board (ABCB) declined this change. Only one bit of the proposed new wording survived the ABCB purge. Clause 7.1.1 of AS 3660.1–2014, basically says that for sub-slab and other areas where you can’t re-enter to spray, you have to provide for another way to replenish the degrading chemical.
Basically, planning to drill is out. So instead, to comply with AS 3660.1–2014, you must provide reticulation to replenish the chemical. Or, like most of the nation, you could forget sprays, use collars and a decent slab (one complying with AS 2870 or AS 3600) with your favourite perimeter system and forget about treating the soil. You can still do ground sprays. The highly resilient ‘Part A’ and ‘Part B’ concepts are not banned it is just that you have to provide for the future.
Everything must have been tested to AS 3660.3-2014
Peppered throughout AS 3660.1–2014 and the BCA–2016’s termite provisions are references to testing to AS 3660.3–2014. For a new chemical, product or system to comply with the provisions of AS 3660.1–2014, it has to be tested in accordance with AS 3660.3. The BCA (Building Code of Australia) effectively requires that, from 1 May 2017, all pre-construction termiticides are APVMA registered and tested to AS 3660.3. It may well be that some of the products you are using or intend to use have not yet passed this hurdle. It is a good idea to check with your suppliers to have them confirm in writing that their product is suitable for use to comply with the BCA–2016, having been tested to AS 3660.3–2014.
Vapour barrier retention problem
This has been covered earlier, but basically, you aren’t allowed to cut back the builder’s poly from the buried slab edge. Typically, it has to be left in place, right up to finished ground level. This contradicts AS 3660.1 at Clause 7.3(d), which requires “At a concrete perimeter, chemical products shall be applied so as to maintain direct contact with concrete slabs”. If you remove the polythene so your chemical can reach the concrete, the building doesn’t meet the Building Code any more. But let’s ignore that, like most of the industry has been doing for years now, and press on.
Reticulation – what must the pipes do?
The bottom line is that a reticulation system is designed to deliver chemical evenly, now and in the future and must not burst, fail, perish or get gummed up over the life of the building or 50 years. Remember you are putting it under a slab (floor or path or whatever) where you can’t get back in to do repairs. The reticulation system must not get dug up, eaten by pets, wrecked by gardening, blocked by roots or become surrounded by impervious soil (too compressed for even delivery). Even if you aren’t in Queensland but install in NSW, if your system fails after your warranty, say as soon as year 8 or 10, your grumpy claimant is likely to find and rely upon the manufacturer’s five decades claim for Queensland and might just get a sympathetic judicial ear. Don’t scrimp.
Where does the chemical go in the soil?
There must be gaps between soil particles so the applied liquid can penetrate. Labels assume that 10% of the dirt is open space to be filled by the liquid. In gravel or coarse sand the gaps are a lot more (sometimes over 40%) and in compacted silt or virgin clay the gaps may be down to effectively nothing. How well does the chemical distribute if you only put in a quarter of what’s needed to fill all the gaps or if there is nowhere for it to soak? As the soil settles after construction (gravity), the gaps keep getting smaller. Reapplication under pressure can blow through the compressed dirt, but water always follows the path of least resistance, so there is an increasing chance over time that the reapplication won’t be particularly even. This doesn’t yet seem to be a problem with any of the surviving systems, but 50 years from now is a very long time.
Know your system
It is important to understand the advantages and limitations of the systems you choose to install. Each system seems to have been tested at a different line length. You may be restricted to 50, 16 or even 10 metres before a second fill point must be added. A system with emitters that limit the flow rate exiting the holes should be far more forgiving of variations in height, than one that has simple, open holes. Altis rate theirs for several metres of height variation. Simple, open holes may be a bit less prone to gunk blockage (over extended time) if pipes are not flushed or if poor quality water is used. Who knows what the years will tell?
Which chemical?
I’m a firm believer in the axiom that you should only use a repellent termiticide where you can be absolutely certain of achieving a 100% even distribution to every possible path a termite might take.
Can I pump up someone else’s system?
Yes, you can, but do you really want to? There’s lots to know about what’s installed. Is the system intact? Is it competently installed and providing adequate service? What pressure and volume is needed at each fill point? What if there’s a fault and it fountains on filling or chemical pours out from under a corner of the slab? What if I’m left carrying a warranty claim? Have you just voided their original warranty? It is good to remember the case of the pest control company who had a problem with a pipe, and their run off killed 2km of creek and 1000 rare spiny lobsters in a national park, resulting in horrible publicity and a $10,000 fine. Is the profit going to justify the risk?
Dr 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 [email protected]
