Cracked windshield: what kind of crack it is, why it spreads, and what to do today
Most cracked windshields start as a chip from a stone, and heat does the rest. A chip, a star break and a short crack away from the edge can often be filled with resin. A long crack, an edge crack or damage in front of the driver usually means new glass. Whatever the crack, it grows: the sooner it is looked at, the more likely a repair still works.
A windshield is laminated: two layers of glass with a plastic layer between them, which is why a cracked one holds together instead of falling apart the way a side window does. The crack can still grow. The exact limits our crew works to are on what a windshield crack repair can really fix.
The types of windshield crack
- Chip, or bullseye
- A small pit where a stone took a piece out of the outer layer, often with a round dark ring around it. The most common damage and the one most often repairable, depending on its size.
- Star break
- A chip with short cracks running out from the centre like the legs of a star. Small ones can usually be filled, though the shape may stay faintly visible. Each leg is a place for the break to grow.
- Combination break
- A chip and a star in one, or several kinds of damage together. The more types in one break, the less likely a repair is.
- Edge crack
- A crack that starts at, or runs to, the edge of the glass. Heat is the usual cause: the metal frame warms the edges faster than the middle. Edge cracks grow long and touch the seal, which is why they often mean a new windshield.
- Floater crack
- A crack that starts in the middle of the glass, away from the edge, often from a chip that was left alone. Caught before it reaches an edge, it may still be saved.
- Stress crack
- A crack that appears with no impact at all, usually starting at the edge. Covered in its own section below.
Why a crack spreads, especially here
- Heat. Glass expands as it warms and shrinks as it cools. A windshield parked in the midday sun is hot at the edges and cooler in the middle, and a chip is where that strain lets go.
- Cold air on hot glass. Getting into a car that has baked all afternoon and putting the aircon on full, aimed at the windshield, is the quickest way to turn a chip into a line.
- Rough roads. Potholes, speed bumps taken fast and unpaved roads flex the body, and the glass flexes with it.
- Slammed doors. The pressure and the jolt both travel into the glass.
- Water and dirt. Rain and wash water get into an open chip, and grit in the break makes it harder to fill cleanly later.
A chip left through weeks of hot afternoons and cold aircon is under that strain every day.
Why a windshield cracks with nothing hitting it
A stress crack is the one that appears overnight in a parked car. It usually starts at the edge of the glass, and the cause is one of these.
- A chip nobody noticed. Most cracks that appear from nowhere start at a pit too small to see from the driver’s seat.
- A sudden temperature change across the glass, as above, with no visible chip at all.
- Uneven pressure from the fitting. A windshield that was set badly after an earlier replacement sits under strain at one point.
- The body flexing. Age, earlier accident damage and heavy loads move strain into the glass.
- A flaw in the glass itself, which tends to show as a crack starting at the edge.
A stress crack that starts at the edge is harder to repair than a chip, and the chance falls as it lengthens.
What to do today, before it is repaired
- 1. Cover a fresh chip with a piece of clear tape on the outside, so dust and rain stay out of the break until it is filled.
- 2. Park in the shade where you can. If the car has been in the sun, let the cabin cool with the windows open before turning the aircon to full, and do not aim the vents at the glass.
- 3. Close the doors gently, and take the bumps slowly.
- 4. Keep a pressure washer away from the damaged area when the car is washed.
- 5. Measure it, or hold a coin against it, and note where it is. Size, shape, distance from the edge and whether it is in the driver’s line of sight decide between repair and new glass.
Scratches are a different problem from cracks, and fine ones can be polished out. Which is which is on windshield scratches.
Have the crack looked at where the car is parked
Our windshield crack repair is done at your address: the crew checks the size, shape and position first, says whether it can be filled, and if it can, injects resin into the break and hardens it in place. The crew works in Pampanga, Bulacan, Bataan, Tarlac and Olongapo, and in Pasig, Cainta, Taytay, Antipolo and Marikina. See every area we cover.
Put the town in the form and say how big the damage is and where it sits on the glass. A photo helps if you have one.
Sources
- Novus Glass, five types of windscreen cracks: stress, edge and floater cracks, chips, bullseyes, stars and combination breaks, and the heat, rough roads and slammed doors that make them worse. novusglass.com
- Ceramic Pro, what causes windshields to crack without impact: temperature extremes, faulty installation, body flex and manufacturing defects, with stress cracks starting at the edges. ceramicpro.com
- AutoDeal Philippines, how to repair a chipped or cracked windshield: laminated safety glass that does not shatter into shards, and why chips should be fixed straight away. autodeal.com.ph