★★★★★
It's an ideal environment and situation!
When a crack runs across a windshield, the first question is repair or replacement. Forums and friends' advice run the full range from "any crack can be filled" to "crack repair doesn't work, replace only". Neither is right: crack repair has clear limits, and they depend not just on length but on position, direction of propagation, presence of sensors, and even whether the crack runs straight or wanders. Below: the industrial line between repair and replacement, how it works at our studio in Tbilisi, Georgia, and why Georgian inspections are stricter in the driver's zone than many drivers expect.
Three length zones: repair, complex repair and replacement
Our studio uses a three-tier size grading.
Up to 15 cm — simple repair, from 95 ₾. A fresh crack up to 15 centimetres, not reaching the edge of the glass and not in the driver's zone — repairs with a vacuum-assisted polymer resin injection in 45-60 minutes. After UV curing, the crack stays as a thin line against daylight but is structurally closed: propagation stopped, strength restored.
15-30 cm — complex repair, from 140 ₾. A long crack with several potential propagation points. The repair runs in 2-3 passes: the technician breaks the crack into segments, positions the injector over each in turn, fills with resin and cures. Work time: 90-120 minutes. The optical uniformity is slightly less than on short cracks, but structural strength is restored.
Over 30 cm — replacement only. Past this length the crack enters territory where resin can no longer guarantee continuous fill, the UV lamp can't cure evenly, and structural integrity is too compromised. Attempts to "fill" a 40 cm crack end the same way — within 2-4 months the crack continues from the same point, and the whole windshield is eventually replaced anyway.
Current prices for crack and chip repair are on the windshield crack repair service page. The final figure for a specific case is set at in-person inspection, where we measure length, assess direction and position relative to the driver's zone.
Why these specific limits — three reasons
The limits are not arbitrary. Three physical and regulatory factors sit behind them.
Structural integrity. A windshield is laminated glass: two panes with a polymer interlayer. Strength depends on continuity of both layers. A short crack filled with resin restores up to 90% of original strength. A 30+ cm crack compromises the glass in a crash — when the passenger airbag fires, a weakened windshield pops out instead of reflecting the airbag.
Risk of further propagation. Every crack tip is a stress concentrator. On short cracks, resin relieves that stress. On long cracks the effect is incomplete: tip stress stays high, and any thermal shock produces new growth. The numbers: a 10 cm crack holds 5+ years in 95% of cases; a 25 cm crack in 70%; a 35 cm repair in 30%. The "repair / replace" line sits where success probability drops below 80%.
Driver visibility. Even a perfect repair leaves a thin optical line. Short cracks at the edges don't interfere. Long cracks through the central field of view produce rainbow fringes under oncoming headlights — distracting at night.
Even if a studio is technically capable of a 40 cm repair, a responsible technician won't sign up for it — the risk of a call-back with further propagation is too high.
The driver's zone: why Georgian standards are stricter
Georgian inspection and international practice recognize a separate zone: the driver's primary viewing area (PVA). It is a rough 50×60 cm rectangle in front of the steering wheel, matching the driver's line of sight.
Under Georgian standards (and ECE R43, which Georgia follows as part of its European framework), damage in this zone is treated more strictly. Any chip or crack in the PVA is grounds for a "repair or replace" notice at inspection. A repaired damage in the PVA is only permitted if optical distortion stays within defined norms. In practice a 5 cm PVA crack typically goes to replacement — distraction and glare outweigh the savings.
This isn't Georgia-specific — it's the European standard. The US is more permissive, but we work in Tbilisi and follow local norms.
To tell whether your crack sits in the driver's zone: stand outside the car in front of the driver's seat. What you see through the glass at eye level is the PVA. Everything outside that — top of the glass, bottom near the wipers, side edges — can be repaired at much larger sizes.
How to measure the crack yourself properly
A common self-measurement mistake is straight-line length. You run a ruler from one end of the crack to the other and read the number. But cracks are rarely straight — they meander, with branches.
The right way: use a flexible tape or a piece of string. Run it along the crack from start to end, following every bend. What you read is the true length. If the crack has a branch, measure the main line and the branch separately; repair length goes by the longer of the two.
A typical case: straight-line length of 12 cm, true length with bends of 18 cm. That moves the crack from "up to 15 cm" into "15-30 cm" category and changes the repair price from 95 ₾ to 140 ₾. That is why the final measurement is done by the technician at intake.
Second — direction of the crack. If the crack runs straight up or down from the impact point (vertical), one situation. Horizontal — another. Reached the edge of the glass — a third (replacement straight away). At inspection we check all three parameters.
The first 24-48 hours — why going in right away matters
A crack, unlike a chip, is a dynamic process. A chip can "sleep" for weeks. A crack sits in a state where any external influence — temperature, vibration, pressure — gives it room to extend.
In the first 24-48 hours, the crack is still clean of dust and moisture, the tips are uncontaminated, and the glass hasn't been thermally cycled with the new configuration. In that window, a 10-15 cm crack repair produces a near-defect-free optical result, and structurally holds 95% of original strength.
A week in, dust inside the crack leaves a dark shadow even after filling, and moisture demands extra drying. A month in, after temperature swings, the crack is often longer — and what could have been a 95 ₾ repair becomes 140 ₾ or a replacement.
Industry rule: crack spotted — into the studio within 48 hours. While the car just sits still, book online, and the next day resolves it.
When repair isn't an option — straight to replacement
Four scenarios where we recommend replacement without attempting a repair.
Crack from the edge. Any crack that has already reached the edge of the glass (even if its total length is 8 cm). The edge is a stress concentrator from body deformation during movement, and a crack from there will keep growing regardless of how much resin is filled. It can be stopped only by drilling a "stop drill" — a tiny hole at the end of the crack that disperses stress. But this technique doesn't always work at the edge, and on many marques it's worth going to replacement straight away.
PVA crack longer than 10 cm. In the driver's zone, short 5-7 cm cracks can be repaired with acceptable optical results. More than 10 cm in the PVA — replace: a perfectly filled line will distract on the highway, and Georgian inspection may flag it.
Crack + missing fragment. If the crack starts from a point where a piece of glass has broken out (deeper than the laminate), a repair cannot give continuous fill. Resin has nowhere to go in the "empty" spot. Glass replacement is more expensive but the only working option.
Crack on an ADAS-equipped car passing through the camera's field of view. Modern cars with level 2-3 autopilot and driver-assist systems (adaptive cruise, lane keeping, autonomous braking) have a camera at the top of the windshield. Even a correctly filled crack in the camera's field of view can throw off system calibration. Most manufacturers (Mercedes, BMW, Lexus, Volvo) require glass replacement and recalibration after any repair in this zone.
In all other cases, repair is a working option. Even a 25 cm crack, if it's not in the PVA, not from the edge, and away from the ADAS zone, can be repaired with a long-term result.
FAQ
What length of windshield crack can still be repaired?
The industry standard line runs at 30 cm. Up to 15 cm is a simple resin-injection repair from 95 ₾; 15-30 cm is a multi-pass complex repair from 140 ₾. Over 30 cm — replacement only. The limit isn't arbitrary: beyond 30 cm, resin can't guarantee continuous fill and the crack usually keeps growing within 2-4 months.
Is crack length measured on a straight line or along the curve?
Along the curve — that is, along the actual path of the crack from start to end. A straight-line self-measurement usually underreads — a crack that looks 10 cm can actually be 15. The final measurement is taken by the technician at intake with a flexible tape along the crack, following every bend. Category and price depend on that number.
Crack directly in front of the driver — repair or replacement?
In the primary viewing area (a rough 50×60 cm rectangle in front of the wheel), we typically recommend replacement already at 5-7 cm of crack length. Reason — even a perfectly filled line leaves 1-2 mm of optical distortion, which in the driver's central field of view distracts and creates glare from oncoming headlights at night. Under Georgian inspection norms a PVA crack is grounds for a formal notice. Outside the driver's zone (top of the glass, bottom near the wipers, side edges), repair is acceptable at much longer crack lengths.
How long does a crack repair hold?
A properly executed short-crack repair (up to 15 cm) done in the first days after the crack appears holds for the rest of the glass's service life without re-emerging. A long-crack repair (15-30 cm) holds 5+ years in 70% of cases; in 30% of cases, new growth starts from the edge of the repaired zone within 2-3 years. Repair of a stale crack (older than a month) — the numbers are worse, 20-30% shorter service life. Hence the right sequence: spotted — into the studio within 48 hours.
Can I drive with a crack before replacement or repair?
Short city distances in dry weather — yes. But every trip is a growth risk: vibrations from rough tarmac, thermal swings from winter heater or summer AC, air pressure under motion. A typical crack grows 1-3 cm per week in normal city driving, 5-10 cm after one trip on a rough road. If you need to drive to the studio, go gently — no hard braking, no heater at max. Better to book today and close the issue than rack up kilometres on an already damaged windshield.
Conclusion
The line between windshield repair and replacement isn't an arbitrary number — it reflects the physics of laminated glass and regulatory norms. Up to 15 cm, a crack is reliably closed by vacuum-injected resin with UV curing; 15-30 cm requires a multi-pass complex repair with a slightly weaker result; over 30 cm means replacement, because resin can't fully fill that length.
Crack position often matters more than length. A short crack in the driver's primary viewing area may require replacement, while a long crack at the bottom of the glass near the wipers is a simple repair. The first 48 hours after a crack appears is the window for the best repair result — later, dust and moisture enter and optical quality drops.
Key takeaways:
- Up to 15 cm — simple repair from 95 ₾; 15-30 cm — complex from 140 ₾; over 30 cm — replacement only
- Length is measured along the curve of the crack, not on a straight line
- A crack in the driver's primary viewing area typically goes to replacement already at 5-7 cm
- Crack from the edge, with a missing fragment, or in the ADAS camera zone — always replacement
- Repair within 48 hours of the crack appearing gives the best optical result and longest service life
Book windshield repair at BESTAUTO via the form on the service page, or call whichever studio is more convenient in Tbilisi, Georgia:
- BESTAUTO Guramishvili — Guramishvili Ave. 78, tel. +995 550 000 299
- BESTAUTO Politkovskaya — Anna Politkovskaya St. 51, tel. +995 550 000 199
Both studios are open Monday to Saturday, 10:00–20:00. A free crack inspection comes first — the technician measures length along the actual line, assesses position relative to the driver's zone, and says whether a repair is enough or a replacement is the right call.
