A windshield chip can sit harmlessly for months — or it can spider into an 8-inch crack overnight. Whether your chip spreads depends on a handful of factors, most of which are within your control right now. Here is what determines spread speed and what to do immediately to stop it.
Some chips never spread. A small bullseye chip less than an inch across, located in the upper corner of the windshield, away from edges, can stay stable indefinitely. But a star crack near the edge of the glass, or any chip that gets hit by extreme temperature change, can spread within hours. The most common cause of sudden spreading: driving on a freeway in cold weather right after running the defroster. The thermal shock combined with highway vibration is what turns chips into cracks.
Temperature extremes: sudden heat (defroster, direct sun on cold glass) or sudden cold causes the glass to expand and contract unevenly, putting stress on the chip. Location: chips within 2 inches of the windshield edge are under more tension and spread faster — these often cannot be repaired even if caught early. Chip type: star cracks and combination chips spread faster than bullseye chips. A single clean bullseye is more stable than a star with multiple fracture lines extending outward. Vibration: pothole impact, highway driving, bass-heavy music with subwoofers — all vibrate the glass and can advance a crack. Dirt in the chip: dirt or moisture in the fracture prevents clean resin bonding and can freeze and expand the crack in cold weather.
1. Put a small piece of clear tape over the chip. This is not a repair — it keeps dirt and moisture out of the fracture until you can get it repaired. 2. Do not use the defroster. Avoid parking in direct sun. Temperature stability is your friend. 3. Do not pressure wash or run through a car wash — the water pressure will enter the fracture. 4. Avoid rough roads if possible. 5. Call Auto Renu at 1-800-684-3629 within 24–48 hours — chip repair takes 20 minutes and costs $50–80. Waiting until it spreads turns a $70 repair into a $250+ replacement.
A chip can no longer be repaired when: the crack has extended longer than 6 inches, the damage is in the driver's primary line of sight (California law prohibits repairs in this zone), the chip has multiple fracture lines extending more than 3 inches, or the chip has dirt or moisture deeply embedded. At this point you need replacement. Under California comprehensive insurance, the replacement is covered at no cost to you in most cases — call us and we verify your coverage before you spend anything.
Send us a photo — text or email a close-up to schedule a repair. As a quick self-check: if you can cover the entire damage with a quarter, it is likely repairable. If any crack extends past 6 inches, or the damage is directly in front of the driver's face, it needs replacement. Auto Renu does free chip repair assessments — call 1-800-684-3629 or send a photo and we will tell you honestly whether repair or replacement is the right call.
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