Step 2: Assessing and Acting Upon Design Risks

Subject 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
building? If not accessible:
Use reticulated systems for chemical barriers. Consider removable skirtings to allow inspection of physical barriers or incorporate inspection holes. Use termite resistant materials where barriers are not viable/visible, or where elements occur below barrier systems (refer Appendix A for timber options).

Will the building have access to all areas under the floors?
Patios and similar structures poured on fill often pose problems. Consider pouring continuous suspended slabs where patios are attached to floor slabs.

Will the building have attached structures such as steps, porches, verandahs, hot water systems, air conditioning units and trellises?
Make sure these are included in the barrier system or incorporate a 25 mm gap (min) to allow clear and uninterrupted inspection at the same height as the main barrier. Or use a monolithic slab to include these additional areas

Does the project involve connections between new and existing work?
If yes, check joints between old and new work. AS3660.1 requires a barrier although alternative courses of action are also possible. Involvement from a termite expert is recommended at design stage where difficulties are likely to be encountered.

Does the building involve split level or different floor types?
Check these locations for potential problems in barrier continuity. Amend the design using standard design details from system suppliers (if possible).

Does the building involve dividing walls between units and/or garages?
These situations often pose problems to barrier continuity. Consider pouring continuous slabs beneath the walls or amend the design using standard design details from system suppliers.

Does the building involve a basement?
Barrier locations require careful consideration at design stage – especially placement of vertical barriers. The choice of basement construction and fitout materials is also important – expert advice is recommended.

Does the construction involve infill slabs?
Infill slabs often cause problems. Edges are hidden from view, and it is hard to avoid inconsistencies in the overall barrier system. Lack of access for inspection means chemical barriers must be re-treatable. Applying chemicals through drill holes is also possible but is rarely a viable option. Avoid infill slabs or seek specialist advice.

How will excessive moisture in dark subfloor spaces be avoided?
Moist soil under the house allows termites to make the mud shelter tubes they use to advance up the subfloor structure and into the house. Consider effective perimeter drainage, especially at the base of cut areas. Consider using impervious ground membranes or open sub-floor construction to keep the sub-floor dry and naturally lit.

Does the project include landscaping and paving works?
Plan finished ground and paving heights so as not to disrupt or bypass barriers. Also make sure that construction does not obstruct sub-floor ventilation.