Two-part epoxy can be used to repair minor chips on a glass window edge, but it's not always the right solution — and in some cases it's not safe to attempt at all. Whether epoxy is appropriate depends on the size and location of the chip, the type of glass, and what the window is used for. Here's a practical guide to help you make the right call.
What Kind of Chip Can Epoxy Actually Fix?
Epoxy adhesive works best on small cosmetic chips — typically less than 5–10 mm — on the edge of a single-glazed window where the glass is otherwise structurally sound. The goal is to stabilise the chip, prevent it from spreading, and improve the appearance slightly. Don't expect an invisible repair; glass-clear epoxy will still show under certain lighting.
Epoxy is not suitable for:
- Chips or cracks that extend across the face of the glass
- Any damage to toughened (tempered) or laminated safety glass — these must be replaced
- Double-glazed (IGU) units where the seal or inner pane is affected
- Chips near a corner, which are prone to further cracking under thermal stress
- Any window in a wet area, fire-rated wall, or high-impact zone (e.g. beside a door)
If you're unsure what type of glass you have, check for an etched or printed mark in the corner of the pane. Toughened glass is usually marked "AS/NZS 2208" — and if it's chipped, it needs replacing, full stop.
Understanding NZ Building Code Obligations
Under the NZ Building Code, glazing in certain locations must meet specific safety standards. Clause F4 (Safety from Falling) and the glazing standard NZS 4223 set out where safety glass is required — for example, in low-level panels, beside doors, and in bathrooms. If your chipped window is in one of these locations, a DIY epoxy patch does not bring it back into compliance. You'll need a licensed glazier to assess and likely replace the pane.
For general guidance on the Building Code and what work requires a building consent, visit MBIE Building Performance. Minor repairs to existing glazing typically don't require consent, but always confirm with your local council if you're unsure.
What You'll Need for a DIY Epoxy Repair
If the chip is genuinely minor and the glass is standard annealed (float) glass in a low-risk location, here's how to approach it:
Materials:
- Two-part clear epoxy adhesive (available from Bunnings or Mitre 10)
- Isopropyl alcohol or methylated spirits for cleaning
- Cotton buds or a fine applicator
- Masking tape
- A razor blade or fine craft knife for trimming cured excess
Steps:
- Clean the area thoroughly — any grease, dust or moisture will prevent adhesion. Use isopropyl alcohol and allow to dry completely.
- Mix the epoxy exactly as directed on the pack. Most two-part epoxies require equal parts resin and hardener mixed for 1–2 minutes.
- Apply sparingly into and around the chip using a fine applicator. Overfilling is easier to fix than underfilling once cured.
- Tape off surrounding glass to protect it from smearing.
- Allow full cure time — typically 24 hours, though this varies by product. Don't rush it.
- Trim any excess carefully with a razor blade once fully cured.
Safety note: Work in a well-ventilated area. Wear gloves and eye protection — epoxy resins can irritate skin and eyes. Handle any loose glass fragments with care and dispose of them safely wrapped in newspaper.
Limitations to Be Honest About
Even a well-executed epoxy repair on a glass edge is a temporary or cosmetic fix, not a structural one. Glass is under constant stress from wind loading, thermal expansion and contraction (particularly relevant in NZ's variable climate), and frame movement. A chip can continue to propagate even after repair, especially through a NZ winter with significant temperature swings.
For windows in older NZ homes — villas, bungalows, or 1970s–80s aluminium-joinery houses — it's worth considering whether the whole pane or unit is due for an upgrade anyway. Modern double-glazed units significantly improve thermal performance, which Energywise notes is one of the most effective ways to improve home warmth and energy efficiency.
When to Call a Professional
Call a licensed glazier if:
- The chip is larger than about 10 mm, or you can feel a sharp edge or crack extending from it
- The glass is toughened, laminated, or part of a double-glazed unit
- The window is in a safety-glazing location under NZS 4223
- You're a landlord — under the Healthy Homes Standards, rental properties must be maintained in a reasonable state of repair, and damaged glazing could be a compliance issue
- You simply want a lasting, professional result
Glaziers are not licensed under a statutory board the way electricians or plumbers are, but they are skilled tradespeople with access to the right glass types, cutting equipment, and sealants. You can find a qualified local glazier on tradedirectory.co.nz.
As a rough guide, replacing a standard single pane in a small window can cost anywhere from around $150 to $400+ depending on size, glass type, and your location — but get quotes from local glaziers for an accurate figure.
Window & Glass Association
