After the Rain — What Sydney Homeowners Should Check for Termite Risk

Sydney gets wet. The east coast gets La Niña cycles that dump rain for weeks; summer storms stack up; gutters overflow. Most homeowners think about water damage in terms of ceilings and carpets — the visible stuff. What they don't think about is what happens underneath the house and inside the walls after the rain stops.

Moisture doesn't have to pool visibly to change the risk profile of your home. Water that tracks in quietly — through a blocked downpipe, a slipping roof tile, an AC condensate pipe draining against the wall — changes the moisture level in the soil, in the timber, and in the subfloor. That's not just a water-damage problem. That's a termite-invitation problem. Here's what to look for.

Where water gets into Sydney homes

Most water entry in Sydney homes isn't dramatic. It's slow and hidden, and it often goes unnoticed until something else — a soft floorboard, a hollow-sounding skirting board — prompts someone to look harder.

The common entry points:

Gutters and downpipes. A blocked or detached downpipe dumps water against the wall or at foundation level. On a home with a subfloor, that means constantly wet soil under the bearers and joists — exactly where subterranean termite colonies build their galleries.

Roof tile slippage. Sydney's older terracotta tile roofs shift with age. A slipped tile in the right spot lets water into the roof cavity undetected — causing timber degradation and mould that only surfaces at the next inspection.

AC condensate pipes. A common one. The condensate drain from a split system is often left hanging beside the house, dripping against the wall or onto soil adjacent to the subfloor. Over a Sydney summer that can be 20–50 litres a day running against a weatherboard or a slab edge. It adds up quickly.

Ground slope toward the house. Houses that have had garden beds, pavers, or raised soil levels added since original construction often end up with finished ground that slopes toward the house instead of away. Water that can't drain outward soaks in and sits under the slab.

Why moisture attracts termites

Subterranean termites — the species responsible for most structural damage in Sydney — can't survive without moisture. They're soft-bodied insects; without the humidity they get from soil and timber, they desiccate and die. Their whole foraging strategy is built around staying connected to moist conditions.

When rain changes the moisture profile of soil near or under a house, it doesn't just rot timber. It creates the conditions that let a colony forage farther and faster. Wet soil under a subfloor, high humidity in a wall cavity, water sitting at slab edge — these aren't just maintenance issues. They're the on-ramp.

Moisture doesn't guarantee termites will show up. But persistently elevated moisture near timber is a consistent risk factor we see on jobs.

What to check after heavy rain

You don't need specialist equipment for a basic post-rain check. Here's what's worth doing:

Walk the perimeter. Are gutters overflowing? Is water pooling at the base of the walls? Is the ground sloping toward the house anywhere? These are the first things to look at.

Check the subfloor if you can access it. If your home has a subfloor access hatch, look in. Is the soil visibly damp? Water marks on the bearers? Any standing water or loose timber offcuts that have found their way in? Timber debris on the subfloor soil is one of the worst things to leave there — it draws termites in and they move straight to the structure.

Redirect the AC condensate pipe. Where does it drain? If it's dripping against the wall or onto soil near the foundation, clip a length of flexible hose onto the outlet and run it well clear of the house — to a path or garden bed at least a metre away.

Keep mulch away from the structure. AS3660.1 — the Australian termite-management standard — requires a 75mm minimum inspection zone between soil or mulch and the timber of your house. Don't put mulch in that zone at all. If you want ground cover hard up against the structure, use pebbles, gravel, or lava rocks — they don't feed termites and they drain well. Keep any organic mulch at least 30–45cm back from the foundation, under 75mm deep, and use termite-resistant timbers (cypress, cedar, eucalyptus) if you have a choice — though even those lose their natural repellent oils over time. Mulch doesn't get eaten by termites, but they get attracted to it — once they're at the structure they go straight for the joists and bearers.

Listen for hollow timber near wet areas. Run your knuckle along skirting boards near bathrooms, laundries, and anywhere regularly exposed to moisture. A hollow or papery sound is an early homeowner warning sign — worth flagging for an inspection.

What a professional inspection picks up that you can't

A visual check covers the obvious. What it misses is moisture trapped behind walls, inside roof cavities, or under slab edges where you simply can't look.

Two pieces of equipment make a professional inspection more thorough than a walk-through:

Thermal imaging. A thermal camera reads temperature differentials across surfaces. Moisture behind plaster shows as a cool patch. Termite activity in timber — which retains heat differently from sound wood — shows as a distinct warm or cool zone depending on the situation. You can't see this with the naked eye.

Moisture meter. A direct measurement of moisture content in timber and surfaces. Post-rain, elevated readings tell the story before any rot or termite activity becomes structural. It routinely surfaces localised damp pockets — behind tiles, inside wall cavities, in subfloor timbers — that would never show on a visual inspection.

Both come on every termite inspection — not as add-ons, just as how the job gets done properly.

When to call

There's no fixed threshold, but here's the honest version:

If there's been significant rain AND you've found any of the above — overflowing gutters, a wet subfloor, water tracking down internal walls, hollow-sounding timber near a wet area — it's worth booking a professional termite inspection. Not because something is definitely wrong, but because the combination of recent moisture and older construction is a reliable risk combination.

If your home came through cleanly and everything looks right: an annual inspection still makes sense. Some things you can't see from outside. The job of the inspection is to catch the ones you can't — before they become structural repairs — and if termites are found, our termite treatment options are matched to the situation.

Book an inspection

If you're not sure whether your home came through the recent weather cleanly, I'm happy to come have a look. I bring the thermal camera and moisture meter on every inspection — it's how I work, not an extra. Every house is different, and a post-rain check often turns up things that have been developing quietly for a while. Book an inspection at activetermitecontrol.com.au or call 0405 790 927. I'll give you a straight quote and tell you exactly what I find.