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Weep Holes
Weep holes have had a lot of media attention, with us all being encouraged to ensure our weep holes are not compromised by an external soil or concrete height. Time for the real story.
Weep holes can be compromised by effectively treated soil, and termites cannot enter the home. On the other hand, the brick courses laid below ground level aren't laid with the same attention to detail that the face bricks are, and as a consequence, there are usually some pretty good termite freeways through the below ground mortar joints. Mortar joints are also not termite proof. If your weep holes are compromised by treated soil, by removing the soil to below the weep holes, you can be removing the chemical barrier. This is especially true of the earlier (pre July 1995) chemical treatments that weren't typically installed by trenching techniques.
If you have a home protected using chemical barriers, you must always ensure that the barriers are kept within the labelled expected protection period of the termiticide used. This is absolutely critical with modern (post June 1995) termiticides.
Current labelled expected protection period for the termiticides on the market are
Biflex (Bifenthrin)
250ml/100 litres = 3 years
500ml/100 litres = 10 years
1 litre/100 litres = at least 10 years
Termidor
At least 5 years
Premise (Imadacloprid)
At least 2 years
Dursban (Chlorpyrifos)
10 years under slab and 5 years as a soil perimeter
Be aware that there are some within our industry who will make re-treatment recommendations based on their own hip pocket and not yours. If your contractor wants to re-treat ahead of the labelled expected protection periods, please ask why! © Mark Porter 2002
Get it right the first time!
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