If you’ve watched a crack in your Wagga Wagga home widen through a hot February and then partly close up again by July, you’ve noticed one of the most common patterns in the whole region: seasonal crack movement driven by reactive clay. It’s a genuine phenomenon, not something you’re imagining, and understanding why it happens is the difference between reasonably monitoring a crack and either ignoring a real problem or panicking over a normal one.
Why the seasons drive crack width at all
Wagga Wagga sits on some of the more reactive clay soil found in inland NSW. Reactive clay is exactly what it sounds like: it reacts to moisture, swelling as it absorbs water and shrinking as it dries out. Across a typical Riverina year, that soil goes through a genuine wet-dry cycle: a hot, often dry summer that pulls moisture out of the ground to a meaningful depth, followed by cooler, wetter months (helped along by autumn and winter rain, plus the occasional wet spell off the back of a La Niña pattern) that let the clay rehydrate and expand again.
Footings sit directly on, or close to, that moving clay. As the soil shrinks away from a footing edge in a dry summer, the ground underneath loses some of its support, and the footing can settle slightly at that point. As the same clay swells back with autumn and winter moisture, it pushes back up against the footing, and some or all of that summer settlement is recovered. The wall above rides along with the footing through this whole cycle, and a crack that formed as the footing dropped in summer will often visibly narrow as the footing is pushed back up in winter. That’s the seasonal breathing homeowners across Wagga notice year after year.
What this looks like in a real Wagga home
The pattern shows up most clearly on brick veneer and full-brick homes, where a rigid masonry skin makes even small amounts of footing movement visible as a crack. A homeowner in a suburb like Kooringal, Turvey Park or Estella might notice:
- A diagonal crack at the corner of a window frame that’s barely visible in June, then clearly open by late January or February
- A stepped crack through mortar joints on an external wall that seems to “grow” every summer and then partially disappear by winter
- A gap along a cornice line, at the wall-ceiling junction, that opens in the driest months and tightens up again once the weather turns
- Doors that stick in summer and swing freely again in winter, moving in step with the same footing behaviour driving the wall cracking
This isn’t unique to any one construction era. Older strip-footing homes from the 1960s and earlier are especially prone to it because their footings are shallower and closer to the zone of soil that dries out fastest, but even slab-on-ground homes built more recently can show a milder version of the same seasonal pattern at the perimeter, where the edge of the slab is most exposed to moisture swings.
Seasonal movement isn’t automatically a problem, but it isn’t automatically nothing either
The honest, non-alarmist version of this is: seasonal opening and closing tells you the crack is being driven by moisture-related soil movement rather than, say, a corroding lintel or a one-off event like a nearby tree root or a leaking pipe. That’s useful diagnostic information on its own. But “seasonal” doesn’t automatically mean “harmless,” and there are two different long-term trajectories a seasonal crack can take.
The genuinely stable pattern. Some cracks open every summer and close by the same amount every winter, cycling back to roughly the same baseline width year after year. This is essentially the footing (and the house above it) breathing with the clay without any net loss of ground support over time. Our guide to foundation crack types: serious vs cosmetic covers how width and pattern combine to sort cosmetic cracking from cracking that needs attention, and a genuinely stable seasonal crack most often falls on the cosmetic or minor end of that scale.
The ratcheting pattern. In other cases, a crack opens further each summer than it closed the previous winter, so the baseline width creeps upward year over year even though the seasonal swing looks similar each cycle. This is the pattern that matters, because it means the footing isn’t fully recovering, some component of each summer’s movement is becoming permanent. Left long enough, this kind of ratcheting settlement is exactly the mechanism that eventually shows up as a genuinely dropped corner, a visibly sloping floor, or brickwork displaced enough that a professional recommends underpinning to fix it properly.
The only way to tell these two patterns apart is to measure, not eyeball. Photographing a crack with something for scale, in the same month each year if possible, and ideally applying a simple tell-tale gauge across it, turns “it looks about the same” into an actual record you can compare. Our guide to cracks in walls: when to worry sets out the width thresholds and warning signs that suggest a crack has moved from ordinary seasonal breathing into something worth a professional look.
What to do about a crack that opens and closes with the seasons
- Don’t fill it while it’s still cycling. Patching a crack mid-cycle, especially in summer when it’s at its widest, means the repair is likely to crack again as the clay rehydrates and the wall moves back through winter. Filling is best done once you understand the crack’s actual behaviour, not on whatever day you happen to notice it.
- Photograph and date it, ideally at the same time each year. Comparing a dry February to the previous dry February, rather than to a wet July, is the fair comparison that actually tells you whether the baseline is drifting.
- Check moisture sources around the footing. Downpipes discharging near the wall, garden beds watered right against the house, and mature trees close to the footing line can all exaggerate the normal seasonal swing, sometimes enough on their own to turn a mild pattern into a more pronounced one. Our drainage and moisture correction service covers the common fixes.
- Watch for a ratcheting baseline over two or three years, not just one summer. One season of extreme heat or drought can produce a wider-than-usual crack that still recovers over the following wet season; it’s the multi-year trend that tells you whether the movement is settling into something permanent.
- Get a foundation inspection if the crack is widening beyond about 5 mm, isn’t fully recovering each winter, or is turning up alongside other symptoms like sloping floors or sticking doors. A foundation inspection can also include a floor level survey, giving you a millimetre-level record of movement rather than a visual impression.
Frequently asked questions
My crack closes almost completely every winter. Does that mean it’s fine?
It’s a reasonably good sign, since it suggests the footing is recovering most of its summer movement rather than settling permanently. It’s still worth keeping a dated photo record over a couple of years to confirm the baseline isn’t slowly widening, particularly if the crack is more than a few millimetres at its summer peak.
Why does this happen more in Wagga than in other parts of NSW?
Wagga Wagga and the wider Riverina sit on some of the more reactive clay found in the state, combined with a climate that swings between genuinely hot, dry summers and wetter cooler months. That combination of soil type and climate produces a stronger seasonal signal here than in areas with sandier soil or a less pronounced wet-dry cycle.
Should I water my garden near the house to try to stop the crack opening in summer?
Deliberately watering right against a footing to counter clay shrinkage can help even out the extreme swings some homeowners see, but it needs to be done evenly around the whole perimeter, not just near a visible crack, otherwise you can create a new uneven moisture pattern rather than solving the existing one. It’s worth discussing with a professional as part of a broader drainage and moisture assessment rather than guessing on your own.
Is a crack that opens and closes with the seasons ever an emergency?
Rarely on its own, but width matters more than the seasonal pattern. A crack that’s opening past around 15 mm at its widest, showing a vertical step you can feel with your hand, or paired with a wall that looks like it’s bulging or bowing, warrants prompt professional attention regardless of whether it also partially closes in winter.
Get a proper read on your crack’s pattern
If you’ve been watching a crack open and close with the seasons and aren’t sure whether it’s settling into a stable rhythm or slowly getting worse, get a free quote and an independent licensed contractor can inspect it properly, including a floor level survey where it’s warranted, and tell you honestly what the pattern means for your home.