Weep Holes, Ant Caps and the 75mm Rule: The Small Gaps That Let Termites In

Termite inspections aren't only about finding termites. Most of the job is checking whether a house is set up to hide them. Three small, unglamorous building details do most of that work: the slab edge inspection zone, weep holes and ant caps. Get familiar with these and you'll understand more about your home's termite risk than most homeowners ever do. It's the core of what a proper timber and pest inspection actually checks.

Three Small Details, One Big Job

None of what follows is complicated. That's the point. These are all simple, visible, physical gaps built into a house on purpose. When they're left alone, they work. When they get covered up (usually by landscaping, storage, or a garden bed nobody thought twice about), they stop doing their job, and that's when conditions turn conducive to termite attack.

The 75mm Slab Edge Gap

On a brick veneer home, AS 3660 calls for a minimum 75mm clear gap between the bottom row of bricks and the finished ground or paving level. That strip of exposed slab edge is the termite inspection zone. It's the one place termites can't tunnel through unseen, because there's no cover for them, and it's the one place an inspector can quickly check for the mud tracking that signals termite activity.

We see this gap built over constantly: new builds especially, but established homes too, wherever paving or garden beds have crept up over the years. Once it's gone, both the termites and the evidence of them disappear from view together.

Weep Holes: Small Holes, Big Job

Weep holes are the small gaps left unmortared in the brickwork, usually just above ground level. Their job is ventilation: letting moisture that gets into the wall cavity escape, and letting air circulate through the cavity so it dries out. Simple mechanism, does exactly what it needs to.

What Blocks a Weep Hole

Soil banked up against the wall. Mulch piled too high in a garden bed. Pavers laid without clearance. Firewood or pots stacked against the brick. Any of these will block a weep hole, and once it's blocked, moisture that should be escaping gets trapped inside the wall cavity instead. That's a genuinely damp, dark, undisturbed environment, which the standard describes, accurately, as highly conducive to termite activity. The fix is almost embarrassingly simple: keep at least 75mm of clear space below every weep hole, always.

Ant Caps: The Subfloor's Early Warning System

In subfloor construction with timber stumps or piers, ant caps are the metal caps fitted at the top of each stump or pier, right where it meets the bearer. They're not there to stop termites physically. Termites can get around a cap easily enough. They're there so a termite entering the subfloor from the ground has to cross an exposed metal surface to reach the timber above, and that's where they leave visible mud tracking. It's a deliberate inspection point, built into the structure specifically to make our job easier.

Where ant caps are missing (and we do find this, particularly in older subfloor construction), that early warning sign is gone. It doesn't mean termites are more likely to get in. It means if they do, nobody's going to know until the damage is well underway. Missing ant caps mean we recommend more frequent monitoring, simple as that.

Why These Three Show Up Everywhere We Inspect

What's notable is how consistently these three issues turn up, regardless of the suburb or the age of the house. We see obscured slab edges on new builds in Officer as often as on established homes in the older bayside suburbs. We see blocked weep holes on properties with tidy, recently landscaped gardens just as often as on neglected ones, sometimes more, because a fresh landscaping job is exactly when someone banks soil up too high without thinking about what's behind the brick.

What You Can Check Yourself This Weekend

You don't need a trade qualification for this. Walk the perimeter of your house. Look at the base of the brickwork. Is there a clear, visible gap between the bricks and the ground or paving (roughly three finger-widths, which is about 75mm)? Can you see weep holes, and are they clear, not choked with mulch, soil or garden edging? If you've got subfloor access, take a torch down and check the tops of the stumps or piers for caps, and look for any mud-like tracking on the ant caps that are there.

None of this replaces a proper inspection, but it's a genuinely useful five-minute check any homeowner can do, and it costs nothing beyond a bit of time and a torch.

Book a Timber and Pest Inspection That Checks the Small Stuff

These three details are exactly what we're trained to check first, every time, because they tell us more about a property's real termite risk than almost anything else on site. If you're buying, selling, or just haven't had your home looked at in a while, book a timber and pest inspection with Littlefire Building Inspections. We inspect to AS 4349.3, we photograph everything we find, and we'll tell you plainly whether your slab edge, weep holes and ant caps are doing their job. Book online at www.littlefire.com.au.