Noosa pest manager Jay Turner explains his cautious attitude towards the use of treated timber, giving some examples of why termites should not be underestimated.

Throughout my training as a termite tech, I was constantly reminded that treated timbers are purely resistant to termite attack, rather than being ‘termite proof’! Whether it was on the job by my mentors or during my schooling, I was regularly told how treated timbers only gave termites a ‘gut ache’, it didn’t stop a determined termite attack. The termites could still build their mud leads up and over treated timber, up cracks or splits in the timber and even up through the core of the untreated section of timber.

After becoming a fully qualified termite technician, it didn’t take long to see many such examples, especially when moisture was involved, whether it be due to a leaky shower or treated timber in direct contact with wet or very moist soil. Witnessing Nasutitermes sp. construct a lead up the outside of a treated pine pole or Coptotermes sp. destroy some treated framing timber left on the ground in the weather for a few years, is pretty common. But it was only recently that I came across a great example of termites actually eating their way up the ‘guts’ of relatively dry treated timber (main picture above)!

I constantly use these examples to stress to my clients the importance of regular inspections despite them having a termite management system installed during construction. We all know that not all treated timbers are the same, with not only different levels of treatment (H1-H6), but different preservatives used (CCA, ASQ, LOSP, PEC, etc). Even the penetration of the same treatment into the same timber type using the same process can vary for a number of reasons; moisture content during treatment, sapwood content and thickness of timber, just to name but a few.

A good example of this is when we occasionally see a treated paling fence, where one or two palings have been completely ‘smashed’ by termites yet the remainder of the palings remain untouched.

The depth of penetration of the preservative has always been a topic of debate for myself with many builders, lumber dealers and other fellow termite industry professionals. The opinions are just as variable as the level of treatment itself. Interestingly though, the treatment of freshly cut ends of treated timbers has always been strongly recommend by our industry, but barely if ever performed by the tradesman cutting the timber. So it is always reassuring when we see first-hand examples of what we preach and recommend.

During a recent standard annual termite inspection on a relatively new suspended floor home, I quickly observed the client had enclosed an area to create a bit of a storage facility beneath the home. The client had tried to do the right thing by using treated timber, however the timbers were in direct contact with the sandy soil, leading up to the house itself. So, as I recommend for all potential bridging points such as this, I quickly made the recommendation to ‘trim’ or cut the timber to separate the direct connection with house.

Treated timber in contact with the ground

Before I had even finished the how and why part of the conversation, the client had dragged out his reciprocating saw and started to make the recommended adjustments. What we both observed next could not have been scripted any better. Just as I had forewarned, termites had already started munching their way up the core of the treated framing timber, totally concealed! However what I would not have predicted was the species responsible for this potential breach.

Microcerotermes sp. is a very common species in my area but is only occasionally detected in housing timbers. However, in this case, I guess they decided to make an exception to the rule and reminded me not to underestimate them.

Trimming of the remaining timbers revealed a similar scenario in four of the six vertical timbers. The highest they had travelled was only a few inches above ground level, so they still had a long way to go, but that was enough for the client to totally rethink his design and make some serious changes beyond just trimming the timbers.

Timber ‘trimmed’ to break the bridge between the soil and the house

There are days when I feel everything I am reporting on are just generic recommendations to keep my insurer happy, but it’s on days like these and clients like this that make my (our) job so rewarding. It also reminds me that just because I haven’t seen it happen, it doesn’t mean it can’t happen and that no matter how much we think we know, we are constantly learning and seeing new things.

Jay Turner, Owner, Laguna Pest Control, Noosa

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