Termites and Buildings
It is conservatively estimated that termites infest and cause damage to 1 out of every 5 houses in Australia. This ratio includes houses in Melbourne and Sydney and Perth where the incidence of termite infestation is much lower than that which occurs in the warmer subtropical and tropical areas of Queensland. Furthermore, destructive species (Schedorhinotermes. SPP in the S E QLD area and Mastotermes in the tropical north) of termites are prevalent in Queensland that are nonexistent or very rare in the Southern Sates, this means that a termite infestation in Queensland can be much more serious issue than it might be in Sydney or Melbourne.
Older “Queenslander” style houses and the new slab on ground construction
Before the invention and widespread use of chemical pesticides during the 1950s houses in termite prone areas like Queensland were built to minimise the risk of termite infestation by raising the floor high off the ground using piers made from termite resistant timbers. This gave rise to the style of house called the “Queenslander”. Steel caps (ant caps) were placed on top of the piers to force the termites to make large mud structures over the caps before they could gain access to the house. Home owners regularly poured sump oil around the base of the piers and were easily able to inspect for signs of termites as they were able to walk freely around under their house.
During the Late 1950s and early 1960s builders realized that these new pesticides we so effective and long lasting that it would be possible to build houses in Queensland with concrete slabs poured on top of a layer of pesticide and that these houses presented little risk of termite infestation. The chemicals used we called Organic Chloride and they had the advantage of crystalising in the soil structure and remaining active and effective termite barriers over very long periods of time. The new style Slab on Ground style homes were superior in many ways to the old timber floored homes and the added advantages were that they were cheaper, faster and easier to build. Pretty soon everyone stopped building the traditional Queenslanders and hundreds of thousands of the new slab on ground houses were built.
The dangers of Organic Chlorides discovered
During the 1970s and 1980s disturbing facts were beginning to emerge regarding the unwanted side effects of these Chlorinated Hydrocarbons(Organic Chlorides) to people and the environment. Widespread use of their use in agriculture and industry were phased out first and slowly during the early 1990s successive pesticides were withdrawn from use in Queensland until in 1995 the last remaining organic chloride chemical was withdrawn for the protection of buildings in Queensland.
The building industry was in unenviable position even if they had the skills to build the older style Queenslander homes the public were demanding the cheaper slab on ground style homes for a few years the only protection available to homes was the very ineffective Organic Phosphate Chemicals some newer unproven synthetic pyrethroid chemicals and a hugely expensive stainless steel mesh to replace the pesticide barrier under the slab.
The re-emergence of termites as the largest risk to homes
Because of the effectiveness of the organic chlorides a whole generation of homeowners never had to give a second thought to the dangers of termites to their home and now the new homes being built were not only lacking a reliable termite barrier but the knowledge of how to reduce the risk of termite infestation to homes had been lost from the general publics awareness.
New methods of protection
New methods of deterring termites had to be introduced and many new products were introduced to the market, even today the industry is still trying to reach the previous levels of protection from termite infestation that the older style pesticides provided and the unfortunate fact is that it’s probable that we will never see another method that will be as effective and maintenance free as the old Organic Chloride chemicals.
The Monolithic slab
Probably the most important development since 1995 is the adoption of forward thinking home builders and designers of the “monolithic slab design”. In this design the slab floor is poured in one piece on top of the ground, all the penetrations through the slab are sealed to prevent termite entry and the entire perimeter of the slab edge is visible.
Theoretically the slab itself forms an impenetrable barrier to termites. Any termites gaining access to the building are easily betrayed by the presence of mud shelter tubes on the exposed slab edge.
It is important to remember though that as good as this development was is still has many serious shortcomings. Most importantly:
- At least 75mm of the slab edge must be visible around the entire perimeter of the building
- Although the slab is design to resist cracking under normal conditions any soil movement under the slab may cause it to crack
- The system does not prevent termites from accessing the home over the exposed slab edge
- The system does nothing to deter termites
- The system is easily compromised. (for instance by covering the slab edge with a garden bed)
- The slab edge needs to be regularly inspected for signs of termite attack
Other important developments
Following the relative success of the monolithic slab important innovations have been developed these are:
- Non repellent termiticides
- pre-impregnated termiticidal blankets
- Termite interception and colony elimination systems.
Just as the changes in construction methods from the “Queenslander” to the slab on ground style home has provided challenges to the way we protect our buildings from termites these changes have also presented many challenges and limitations to the inspections of homes for termite activity. To compound this problem Insurance companies are very specific about the wording and limitations that are required in any report. Any termite report that does not contain these limitations has undoubtedly been prepared by someone who is either uninsured by choice or uninsurable due to their lack of qualifications or previous negligence.
Termites are secretive by nature and often only the slightest signs betray their presence. In Australia we are very lucky to have some the world leaders in termite detection and inspection. These respected industry experts produced two Australian Standards dealing with termite and timber pest inspections. These are:
- AS4349.3 Inspection of buildings Part 3 Timber pest inspections
- AS3660.2 Termite management Part 2 SECTION 3 Inspection and detection
A termite inspection carried out by a suitably qualified person following the guidelines and using the equipment specified in either of these Australian Standards will alert the property owner to any risk areas and report on the presence of termites in the house to the extent that it would be reasonable to expect that a qualified and competent inspector would be able to discover them.
In Plain English this means that although there are limitations to the report the information contained in the report is based on the careful and diligent observations of a qualified person following the guidelines of the most experienced and knowledgeable people in Australia and although the report has limitations it does not in any way absolve the inspector from not reporting on any risk or termite activity that would be discoverable by a qualified person following the guidelines set out in the Australian Standards
Specific answers to comments
Firstly there is a termimesh system in place. I thought that was the system to hold the white ants at bay. The object of the report surely was to report on its barrier and the presence of white ants
It appears there is a perception that the termimesh system installed to the house is actually an full stainless steel mesh system where in fact according to the notice provided by termimesh all that has been installed is plastic collars over the penetrations and there has been a chemical treatment to the perimeter and the main component of the termite protection is the monolithic slab forming an impenetrable termite barrier. I know this client is important and needs to be treated gently but we need to make him aware that he has no barrier around the perimeter of the building and very little protection from termites. What he decides from that point is 100% his decision but at least from that point onwards there is no repercussions to you.
I guess one way of looking at it is that it is much easier for you to help him take responsibility for the termite protection or lack thereof for his properties now before a problem arises than it would be for you have to deal him after there was an infestation with him still believing he had a house with a full stainless steel mesh protection system.
Or to put it this way if he has 20 houses and he believes they all have “a system that will hold the white ants at bay” it is almost certain one of those houses will get termites in the next 4or 5 years. At that point he’ll probably be screaming at you saying I thought this system was supposed to keep them out.
There seemed to be a lack of getting into places to see if the ants were present with so many cop outs that you would say “what is the point of having an inspection if they don’t inspect!”
I hope I covered that above if you think it needs to be addressed further let me know
All they seemed to want to do is sell us a chemical barrier system. Why would I do that if there is already a system in place?
Guilty as charged, although its not a chemical barrier we want to sell him. But I think we can address these concerns with the revised front cover sheet which I’ll send for your comments. It is true we do like push people towards installing an Exterra system for 3 main reasons
- It’s good business for us
- It’s excellent value for the property owner
- Most Houses on the Gold Coast have seriously deficient termite protection.
HOWEVER I fully understand your position and the delicacy required so we will make sure you are comfortable with the way we approach these issues before we do anything