Construction Improvements for Termite Protection
There are many ways to reduce the risk of termite attack in new constructions.
Here are some of the common building faults that allow termites easy and concealed access into a building.
Exterior paving too high against building wall
This is the most common fault and is probably the worst. External paving or garden beds should be finished at least 150mm below floor level. This means you should step up into a building. In Melbourne’s housing this usually means your finished ground level should be two brick courses below your air vents.
Timber in contact with soil
This is asking for trouble. Often weatherboards are touching the garden bed, or old timber formwork may be left in-situ. It has to be removed.
Timber at risk can be reduced by controlling moisture, using resistant timbers below floor level, avoiding timber in ground contact or using non-timber elements such as concrete masonry and steel.
Photo above shows a timber house wall engulfed by soil and with zero subfloor ventilation. No surprise- it had termites!
Ventilation of sub-floor
Ventilation needs at least two opposite wall vents to be functioning so that a cross flow of air occurs. Termites get adventurous in still air conditions. Make sure those air vents are not obstructed by paving or garden beds.
Many new building as constructed in a way that creates a high termite risk. One example of bad design is the construction of an extension to a home using a different footing method. For instance, adding a concrete slab extension to the side of an existing home with a suspended timber floor. The slab prevents cross ventilation and the slab edge (in the dark of the sub-floor) give termites a large concealed highway on which to enter the extended area.
What about naturally resistant timbers?
Certain species of timber are naturally resistant to termite attack. However, not all timber of a resistant species will be equally resistant and so while these timbers may be used in ground contact or sub-floor, strip shielding is still needed to isolate them from the structure above. Re-growth timbers of resistant species are generally less resistant than old-growth timbers and plantation grown timbers may be even less so.
What about chemically-treated timbers?
Timber treated with CCA (copper, chromium and arsenic) is widely used, but has been tagged by the APVMA as a product to watch and may not be widely used for much longer. Other treatments, especially quaternary ammonium compounds are gradually replacing the arsenic components and have a similar green appearance.
Sometimes construction and environmental modification is all that is required to remedy a termite attack. However, it is more usual for some modification to be used together with other methods such as termite baits or chemical soil treatment.
To learn more about how you can reduce the risk of termite attack in your new construction, call our office during business hours on 1300 69 59 49 or ask your architect for advice.