Termite collars in the wrong place on a Clyde North slab
Why the position of a termite collar on a conduit matters, and why it can only be checked before the concrete goes in.
In short: Termite collars belong inside the slab where pipes pass through it. On one Clyde North pre-pour we found them fitted at the top of the conduits, where they protect nothing.
What a collar is for
Every pipe and conduit that passes through a slab leaves a small gap around it as the concrete shrinks. Termites can use that gap to come up inside the house, out of sight. A collar is a fitted barrier that closes the gap, and it only works when it sits within the slab at the point of penetration.
What we found
At a Clyde North slab pre-pour in April 2026 the collars had been placed at the top of the conduits, above where the finished slab would be. Once poured, the gap through the concrete would have had no barrier at all, and nobody would ever have seen it again.
Why it happens
Collars are fitted by a different trade from the concretor and the plumber, often on a tight program. A collar slid to the top of a conduit to keep it out of the way during set-out is easy to forget. It is a sequencing slip, not a design fault.
What else we checked that day
The same slab had splices in the internal ribs left untied and vapour barrier punctured by pipes without tape or sleeves. Each is minor alone. Together they are the difference between a slab that performs as designed and one that does not.
What to ask your builder
Ask that termite components are installed and photographed before the pour, and that the termite management notice records the system. If you book a pre-pour inspection, collars are one of the items we look at hole by hole.
Written by our local inspection team from work carried out in Clyde North. Licensed building practitioners, Building & Plumbing Commission registration CDB-U 53425.
