Summer Road Trips: Fix That Windscreen Chip Before It Cracks in the Heat
You've had a small stone chip in your windscreen for a while. It hasn't bothered you much — it's off to the side, it doesn't affect your vision, and you've been meaning to deal with it but haven't quite gotten around to it.
Then the Geelong summer arrives. You park the car in the sun at Torquay while you're at the beach. You come back two hours later and that small chip has a crack running from it — sometimes halfway across the screen.
This is one of the most predictable and entirely preventable vehicle damage scenarios in the summer months. Understanding why it happens will convince you to deal with the chip before your next road trip down the Surf Coast.
Why Heat Turns Chips Into Cracks
A windscreen is laminated safety glass — two layers of glass with a plastic interlayer bonded between them. When a stone chip hits the outer layer, it creates a stress point in the glass. The glass around the chip is structurally weakened, and the crack that's waiting to happen is held in check by the existing stress equilibrium.
Summer heat destroys that equilibrium.
When you park in direct sun, the outer surface of the windscreen heats rapidly. The interior of the car heats even more rapidly due to the greenhouse effect — temperatures inside a parked car can reach 60–80°C on a hot Geelong summer day. The glass expands differentially — outer surface, inner surface, and edges expanding at slightly different rates.
That differential expansion creates new stress at the chip site. If the chip is already compromised, the new stress is enough to propagate the crack. A chip that survived winter, spring, and 28-degree days can fail spectacularly on the first 35-degree day.
The crack doesn't stop at the chip. Once it starts propagating, it follows the path of least resistance through the glass — often running to the edge of the screen in minutes.
The Repair vs. Replace Threshold
The good news: a chip caught before it cracks is almost always repairable. Chip repair involves injecting a clear resin into the chip under vacuum, filling the void and restoring structural integrity. When done correctly, the repair is nearly invisible and the structural integrity of the glass is restored.
The threshold for "repairable chip" versus "replace the whole screen" depends on:
Size. Most chips smaller than a 10-cent piece are repairable. Larger chips may not hold the resin correctly.
Location. Chips directly in the driver's line of sight — within the wiper sweep area directly in front of the driver — are typically not repairable because even a successful repair leaves a slight optical distortion that creates a safety concern. These require replacement regardless of size.
Age. Fresh chips repair better than old ones. Over time, moisture, dirt, and road grime contaminate the chip void, making it harder for the resin to bond correctly. A chip you've had for three months will repair less cleanly than one you got last week.
Whether it's already cracked. Once a crack has run from the chip, the calculus changes. Short cracks (under 5–6cm) can sometimes be repaired. Longer cracks, cracks running to the edge of the glass, or cracks that have branched typically require full replacement.
Before Your Surf Coast Road Trip
If you're planning summer drives down the Surf Coast Highway, the Great Ocean Road, or anywhere on the Bellarine Peninsula, a windscreen chip is worth dealing with before you go — not because a chip alone creates immediate danger, but because the combination of heat and road vibration on regional highways is exactly the environment that turns chips into cracks.
A crack that starts on the Great Ocean Road puts you in an awkward position: you either continue the trip with compromised glass (the crack will likely spread further), or you're stuck waiting for a mobile replacement service in a location that isn't convenient.
Deal with it before you leave. The repair takes less than an hour.
Insurance and Windscreen Chips
Most comprehensive car insurance policies in Australia include windscreen cover — either within the standard policy or as an inexpensive add-on. Many windscreen policies have no excess for chip repairs (only for full replacement). Check your PDS for the specific terms.
If your policy covers chip repair with no excess, there is literally no financial reason to delay. Call your insurer, confirm the no-excess arrangement, and get the chip repaired immediately.
Don't Park in Direct Sun If You Have a Chip
In the meantime, if you have a chip and can't get it repaired immediately: park in shade wherever possible, avoid temperature extremes like car washes with hot water jets, and if you park in sun, crack a window slightly to reduce the greenhouse pressure differential inside the car.
These are mitigation measures, not solutions. The chip needs to be repaired.
Call 03 4244 8938 for an assessment or get a quote online.
6 Freedman St, North Geelong VIC 3215 | Mon–Fri 8AM–5PM