| Termite Management for Builders |
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This guide introduces the termite management issues which builders should be aware of. Use the links on your right to navigate to the various sections of the guide. The guide is available as a PDF download (2.5 MB).
IntroductionGood risk management practices can help reduce the risk of damage from termite attack on buildings. This web-guide details these management practices; it is orientated towards helping builders and designers involved in housing construction across Australia. It starts by outlining regulatory and statutory requirements. It then provides guidelines to use in the building process. It finishes by discussing the risk of damage to houses from termites. Three major issues require special mention because of their underlying impact on the above issues:
Termite behaviourThere are more than three hundred and fifty species of termites in Australia but only about twenty or so cause economic damage to houses. These species are mainly subterranean termites. They set up nests underground and in the trunks of trees, and prefer damp dark habitats. They tunnel through the soil then build mud shelter tubes up the side of structures to gain access to buildings.
Termites will travel a considerable distance underground to attack buildings in search of food. Up to 50 m is realistic – some species in the north of Australia are known to travel further. Termites can therefore attack from beyond the property boundaries, so when assessing the risk of attack, bear this in mind.
Termites don’t just attack timber houses. The overall risk of major damage to houses is low, but all types of houses are at risk. A recent CSIRO study (Cookson 1999) found that steel and masonry houses had virtually the same chances of attack as timber houses.
Termites don’t just infest structural timbers. Termites can also damage plasterboard, carpets, plastics, books, artwork, clothes, electrical insulation and fitout timbers.
Not all termites have the same feeding habits. Some species are more aggressive than others. Those in the far north of Australia are particularly voracious feeders. Older and larger colonies will also have a greater impact than newly established colonies. ![]() Termite mud shelter tube
The risk of termite attack varies according to where you are in Australia. The risk varies from being negligible in Tasmania, to high in far northern Australia.
Termites usually swarm in summer in an attempt to start new nests. New nests created by this means are rarely established in buildings unless there is a permanent source of moisture – the main threat is therefore from underground. In any event, it usually takes at least 3 years for a new nest to grow to a size large enough to be capable of causing economic damage. Termite Risk Management Requirements in the Building Code of AustraliaThe Building Code of Australia states that if primary building elements in new building work (including extensions) are susceptible to termite attack, protective measures must be taken. If there is no potential risk, then no protective measures
Termite resistant primary elements are those specifically designed to take building loads. If these elements are constructed of one or a combination of termite resistant materials, no other termite risk management is required by the BCA (although this leaves other parts of the building unprotected). Materials deemed to satisfy this requirement include concrete, masonry, steel (and other metals) as well as treated timbers and naturally resistant timbers. Details on these timbers are specified in Australian Standard AS3660.1 and a summarised list is in Appendix A. Manufacturers of treated timbers can also provide details relating to their products. ![]() Fig. 1: Resistant materials approach
Termite management systems are another method accepted under the BCA. This approach focuses on heading termites off when they come out of the ground by using termite barriers to deter concealed entry into buildings. This approach tends to be more popular than termite resistant materials because of its ability to address the whole of the house, not just the primary structural elements. Barrier systems deemed to satisfy BCA requirements are in Australian Standard AS3660.1. ![]() Fig 2: Barrier approach
Alternative solutions are also possible under the BCA’s performance requirements. Under this approach, approval authorities can assess whether a system complies with the BCA by using a number of recognised assessment methods (check the BCA for details and ensure suppliers of such systems have documentary proof of BCA certification).
The BCA requires that a notice be fixed permanently to the building in a prominent location (e.g. the meter box) providing information about the termite management system used. The notice must be of durable material, and include the specific method, date of installation, the registered life expectancy of chemicals (if used), and the installer’s recommended scope and frequency of termite inspections. ![]() Fig 3: Typical termite management system notice
In addition to the above, variations to the BCA occur due to state/territory specifi c requirements. The Northern Territory and Queensland are two such cases where variations place extra conditions on the use of termite resistant materials, barrier systems, and the requirements for termite management notices. A summary is provided in Appendix B. The BCA should
Other Statutory and Legal ImplicationsState legislation can impose additional statutory requirements to those mentioned previously. This is mainly in the form of fair trading legislation relating to the home building industry. This legislation typically requires designers and builders to show a duty of care towards customers, and though this does not stipulate specific methods of termite management, standards may ultimately need to be higher than those in the BCA in order to satisfy expectations. For instance, the NSW Office of Fair Trading’s publication, ‘Protect Your Home From Termites’ (OFT 2003, page 4) requires protection of the whole house, not just primary structural elements. Queensland’s Building Services Authority is less specific but emphasises that homeowners must be made
The National Registration Scheme for Agricultural and Veterinary Chemicals impacts via the Australian Pesticides and Veterinary Medicines Authority which evaluates the safety and performance of chemicals where used in barrier systems. It constantly monitors the market for compliance, and also stipulates the life expectancy of chemicals used in barriers, thus determining when reapplication is required.
Licensing of barrier installers may represent another statutory requirement depending on the state in question. Most states focus on licensing installers according to health and safety requirements for handling and installing chemicals. Licensing for quality of workmanship is less common. Queensland is one example where installers must have an operating licence issued by the Building Services Authority. In this case, licensees must have attained prescribed competencies and carry professional indemnity insurance (QBSA 2001).
Aside from statutory requirements, contractual stipulations create obligations between the builder and customer. For instance, design documentation may make it necessary to comply with specific Australian Standards, or use specific termite management systems. Where this occurs, the first priority is to check that the specified system meets regulatory, statutory and site specific requirements. If not, the situation should be discussed to negotiate a more appropriate solution.
Termite Management StandardsIn addressing the previous requirements it is relevant to note that a suite of three termite management standards (published by Standards Australia) cover the spectrum of termite management issues. Not all are specified in regulatory documents, so details are given below:
All three standards are available for purchase only from SAI Global. A Focus on AS3660.1AS3660.1 offers a variety of physical and chemical barrier systems deemed to meet BCA requirements. It is important to realise these barriers only deter hidden entry by termites into buildings – they do not keep termites out. Therefore the longer term emphasis is on using the barriers to identify termite entry, and this relies on the building owner having regular inspections conducted – usually by engaging a termite management professional.
Physical barriers involve installing an impregnable material wherever subterranean termites might enter the building from
Chemical barriers use termiticides that kill or repel termites before they enter the building. The barriers are commonly applied to the soil immediately around and beneath slabs and footings. Long life chemicals are no longer registered for this use due to the impact they were found to have on health and the environment. These days, the chemicals do not last the lifetime of the building, and must be periodically reapplied to maintain protection. Options arising from this include:
Examples of physical and chemical barriers applied to common floor construction situations are shown in Fig 4 to Fig 8.
Important Note: Combinations of the following options may be used as required. The options may also be used in combination with termite resistant materials. In all cases a continuous system must be achieved. Systems suppliers should be consulted to obtain appropriate design details as required. All barriers or combinations of barriers are ‘detection systems’ intended to expose concealed termite activity. Consequently, they must be complemented by appropriate ‘inspection zones’. Regular inspections must be undertaken to detect evidence of termites, and therefore complete the system. ![]() Fig 4: Suspended floors with ant cappings ![]() Fig 5: Suspended floors with alternative barrier systems ![]() Fig 6: Slab on-ground with exposed edge ![]() Fig 7: Slab on-ground with covered edge ![]() Fig 8: Slab on-ground with separate barrier beneath Sub-floor Ventilation RequirementsSub-floor ventilation is often a forgotten part of termite management. The BCA (Vol. 2) requires the sub-floor between a suspended floor and the ground to be ventilated. This minimises sub-floor moisture which helps to prevent timber decay, and creates an environment that discourages termite attack. To be effective, acceptable sub-floor construction must:
Unless full underfloor physical or chemical barriers are provided (refer Fig 4 to 8), sub-floor clearance must be provided to enable regular inspection. Where required, sub-floor clearance must be a minimum of 400 mm to the underside of bearer, except on sloping sites where part of the area may be a minimum of 150 mm clearance as shown in Fig. 9. The amount of ventilation depends on the location of the site in Australia. This is governed by relative humidity; the relevant zone can be read off Map 1. Using Table 1, select the appropriate climate zone and read off the required ventilation area per metre of subfloor wall. Amounts vary depending on whether a sealed impervious ground membrane is used or not.
![]() Map 1: Climatic zones based on relative humidity (Source: BCA 2007) ![]() Fig 9: Minimum underfloor clearance - Refer to AS3660.1
High Risk Sites Require Special AttentionEven with appropriate sub-floor ventilation and the whole of house approach provided by termite barriers in AS3660.1, high risk sites still need special attention. This is not a statutory requirement but a common sense approach. It makes sense to boost requirements where termites are known to have a high risk of attack. Project specific design problems may also make it hard to provide construction that conforms to BCA and AS3660.1 requirements (e.g. alterations to buildings that have no barrier in place, or buildings built hard up against the boundary with no allowance for inspection). These points are dealt with in detail later in this guide, but below are some measures that improve the ability to manage these high risk situations:
Creating a Manageable ProcessThe previous regulations, statutory requirements and details on high risk sites cover the main issues in termite management. However these factors come from fragmented sources and do not necessarily reflect the way buildings are actually constructed. To remedy this, a step-by-step approach is shown in Figure 10. It aims to simplify the key issues by placing them in a context that suits the way buildings are constructed. The approach allows elaboration on key issues at relevant stages during the process. It is also more inclusive of those who are not adept at understanding legal, regulatory or technical documents. For instance, there are many parties involved in decision making, including designers, builders, pest managers and building owners. Each of these people have varying levels of knowledge about termites, degrees of involvement, understanding of constraints, and varying levels of stakeholder interest. All parties need to have a common language for understanding who should be involved, what needs to be done, when things need to be done and who is responsible. The steps detailed below aim to make this possible, and in doing so, make sure there are no gaps along the way. ![]() Fig 10: Step-by-step termite management process
Step 1: Assessing Site RisksAs previously discussed, high risk sites require special attention. This needs to be done at the very start of the project. AS3660.1 calls for an investigation within the property for active termite nests up to 50 m from the proposed building. If found, action should be taken to eliminate the colony before construction of the building commences. Though this goes some way to handling obvious risks, nests are hard to find – especially where located beneath the ground or on a neighbouring property. Time may also change circumstances. To deal with these issues other indicators based on the earlier discussion about termite behaviour are useful. Map 2 followed by Decision Chart 1 apply the main points by way of key questions that aim to provide a ready reckoner for identifying high risk sites. Check Map 1 to determine in which category your building site is located. Use this information to determine the path to be taken in Decision Chart 2. For ‘high’ and ‘very high’ risk sites, extra precautions to minimum BCA and AS3660.1 requirements are recommended. Take this into account when undertaking Step 2 (assessing and acting upon design risks) and Step 3 (selecting an appropriate termite management system). ![]() Map 2: Termite map of Australia (Source: Leicester et el., 2003) ![]() Decision Chart 1: Assessing if the site has a high risk of attack
Step 2: Assessing and Acting Upon Design RisksSubject to the site risk assessment, choose a building design that suits. Of note, suspended timber floors with high ground clearance and good sub-floor ventilation are known to perform well in resisting termite attack. It is also important to check the design for problems that may compromise the effectiveness of the termite management system, and act accordingly. The following questions and answers cover problematic areas:
Will the building be accessible for inspection and maintenance – especially if building close to the boundary or another
Will the building have access to all areas under the floors?
Will the building have attached structures such as steps, porches, verandahs, hot water systems, air conditioning units and trellises?
Does the project involve connections between new and existing work?
Does the building involve split level or different floor types?
Does the building involve dividing walls between units and/or garages?
Does the building involve a basement?
Does the construction involve infill slabs?
How will excessive moisture in dark subfloor spaces be avoided?
Does the project include landscaping and paving works?
Step 3: Selecting an Appropriate Termite Management SystemSelecting a Termite Management System should be fine tuned according to site needs and design issues (i.e. Steps 1 and 2). Such needs must be acted upon in accordance with BCA regulations, statutory and local council requirements, legal requirements, and use of AS3660.1. The decision chart below aims to assist. ![]() Decision Chart 2: Selecting an appropriate termite management system
Step 4: Quality of System InstallationA system is only as good as the quality of its installation. The following points highlight some
Step 5: Preventing Problems During Landscaping, Paving and Site WorksBarriers can easily be rendered useless if hidden, damaged or bypassed by landscaping, paving or site works. This same construction can also hamper sub-floor ventilation. It is best to design landscaping, paving and site works at the same time as selecting the barrier system. Frequently asked questions associated with problematic issues are dealt with in this section. ![]() For landscaping, use only treated or naturally termite resistant timbers The plans call for exterior paving, planter boxes and garden beds next to the building. Does this pose a problem? Do not let paving, planter boxes, mulch or garden beds cover physical barriers, weep holes or inspection zones such as slab edges. Barriers must be visually inspectable. For chemical barriers be particularly careful not to disrupt treated soil during excavations. Also do not cover these barriers with garden beds as this will create a hidden pathway around the barrier. Seek additional advice for paving in the Northern Territory and Queensland as paving is required to protect chemical soil barriers but must be positioned correctly. ![]() Fig 11: Proper treatment of paving and planter boxes (left) :: Don't allow garden beds to cover chemical barriers (right)
What type of timber can I use for landscaping? Use only treated timber or naturally termite resistant timber. Other timbers only encourage termite attack. For appropriate timbers refer to AS3660.1 or to Appendix A for a summarised list. ![]() Fig 12: Decks should be isolated from the building
What do I need to look out for when adding a deck or balcony to the house? Ensure the structure is either isolated from the main house or has a barrier system that integrates with the house barrier. It must not breach the existing system. Ensure that stairs, posts, landings and porches can be inspected for termites.
Does rendering or painting the exposed edge of a concrete slab pose a problem? These treatments potentially allow hidden termite entry behind the paint film or render. It is best to avoid these practices if at all possible.
Step 6: Handing Over to the Building OwnerBarrier systems are essentially detection systems not prevention systems. Effectiveness is entirely dependent on regular inspection and maintenance organised by the building owner. Providing information to building owners on this subject is important. It helps owners know what they must do and delineates this from the builder’s responsibilities. Many industry associations provide home owner brochures covering the main issues. It is also useful to have the building owner sign an acknowledgement stating that they understand their responsibilities for the system installed – an example is provided in Appendix C . Further to this, it is important they know that:
Builders can assist in helping owners meet their responsibilities by using installers who provide ongoing maintenance and inspection services.
What is the Risk of Major Damage from Termites?Major damage to buildings from termite attack is rare – fences and landscaping timbers have a higher risk of attack. The issue of termite damage to houses is placed in perspective by a nationwide survey of households carried out by the Australian Bureau of Statistics (1999). It questioned householders on the causes of major structural damage including an option to select termite and wood rot damage. To further investigate the severity of termite damage, the Australian Bureau of Statistics was asked to undertake a special data request by looking specifically at houses built since the inception of termite construction standards in 1967. Other research was used to determine the separate proportions of termite and rot damage (Tyrrells Property Inspections, 1995). From the combined data it was found that major structural damage from ‘termites’ was only present in 0.3% of households in Australia and this occurred over a 9.1 year period of ownership. Comparative findings are shown in Table. 2.
It can be seen that major termite damage is less common than most other problems identified in the survey. For instance cracks in walls and floors were 8 times more likely to occur than termite damage. All other categories (except ‘major electrical problems) are at least twice as likely to occur.
The risk of major structural damage from termites is very low. Maintaining barriers and regular inspections organised by building owners are critical. This can only happen if the building is prepared correctly. The BCA and AS3660.1 provide the underlying principles to do this. Six important steps help convert these requirements to a manageable process on-site:
Appendix A – Termite Resistant TimbersThe timbers listed below represent a summarised account of those in AS3660.1 (2000) and have been guided by commercial availability in different locations iin Australia.
Timbers treated against termite attack must attain appropriate levels of treatment to suit the application involved. Further details are in AS1604 but a selection guide is shown below:
NOTES: Appendix B – State Variations to the BCAQueensland variations to BCA requirements
Northern Territory variations to BCA requirements
Appendix C – Termite Management System Handover Form![]() Fig 13: Typical Handover Form References
AcknowledgementsThanks to the following associations for assistance and input to this guide: DisclaimerLimitations. The information and advice provided in the publication is intended as a guide only. As successful design and construction depends upon numerous factors outside the scope of this publication, the Timber Development Association accepts no responsibility for specifications in, nor work done or omitted to be done in reliance on this information sheet.
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