Most vehicle auto glass repair work is one of a handful of recognisable failures: star breaks, bullseye chips, long cracks, edge cracks, stress cracks and shattered tempered side glass. Type and position decide whether auto glass repair for cars is possible, and whether the job is auto glass replacement repair instead; length alone rarely does.
Windshield Brief connects you with licensed local auto glass companies. We are not an auto glass contractor.
What the numbers are
| Damage type | Usually repairable? | Why |
|---|---|---|
| Bullseye chip (under ~a quarter) | Yes | Regular cone fills predictably with resin |
| Star break with short legs | Yes | Repairable while legs stay short and central |
| Crack up to ~3 in | Yes | Within the general repair threshold |
| Crack 3–6 in | Depends | Judgement call on depth and position |
| Crack over 6 in | No | Past the general threshold |
| Any damage at the glass edge | No | Edge carries the structural bond |
| Damage in driver’s line of sight | No | Repair leaves slight optical distortion |
| Shattered tempered side glass | No | Tempered glass fails completely; cannot be filled |
What is a star break, and can auto car glass repair stop it spreading?
A star break is an impact point with short legs radiating out. Resin repair stops the spread while the legs are short and away from the edge — and it spreads readily if left, because the legs concentrate stress and thermal cycling extends them.
A defroster blasted onto cold glass is a common way to turn a small star into a long crack overnight.
Why is a bullseye the easiest glass repair auto glass repair case?
Because the geometry is regular. A bullseye is a clean circular cone of separated glass around the impact point, so resin fills it predictably and a finished repair is often hard to find.
Under about the size of a quarter, away from the driver’s view and away from the edge, this is the clearest case for repair over replacement.
Why does edge damage mean replacement rather than auto glass replacement repair?
Because the perimeter is where the urethane bond carries structural load. The windshield helps retain the roof in a rollover and gives the passenger airbag a surface to deploy against, and both depend on the bond at the edge.
Edge damage compromises that, which is why it means replacement regardless of how short it looks.
What is a stress crack with no impact point?
A crack that appears without anything striking the glass, usually from a rapid temperature change or flex on an already-stressed pane. There is no chip for resin to bond into, so it is a replacement case.
It is also a signal: glass that cracks without impact was often already carrying stress from a poor previous fit.
Why does side glass shatter instead of cracking?
Because side and quarter glass is tempered, not laminated. Tempered glass is heat-treated so it fails all at once into small blunt fragments — safer in a collision, but it means repair is not possible.
The windshield is laminated: two plies bonded to a plastic interlayer, which is why it cracks and holds together.
Sources
5 cited- Replacement cost: UseCalcPro 2026 windshield replacement cost calculator (checked 2026-08-17).
- ADAS recalibration: glassandauto.com ADAS calibration cost guide 2026; Car Talk; Affordable Auto Glass WI 2026-02-04 (checked 2026-08-17).
- Repair thresholds: Affordable Auto Glass; GlassFixit; Complete Auto Glass; Ultra Bond (checked 2026-08-17).
- Safe drive-away time: National Auto Glass Authority; Windshield Advisor; AGSC AGRSS Standard; I-CAR RTS CRN-125; FMVSS No. 212 (checked 2026-08-17).
- Deductible rules: Policygenius; Progressive; carinsurance.com; Glass.NET (checked 2026-08-17).