How to Fix a Bifold Door with a Cracked Glass Panel

A cracked glass panel in a bifold door is more than just an eyesore — it's a safety hazard and a security risk that should be addressed as soon as possible. In most cases, the glass will need to be professionally replaced rather than repaired, but there are safe steps you can take in the meantime. Here's what NZ homeowners need to know.

Assess the Damage First

Before touching anything, take a close look at the crack. Ask yourself:

• Is the glass still in one piece, or are there loose shards?
• Is the crack a simple hairline fracture, or has the panel shattered?
• Is the glass toughened (tempered), laminated, or standard float glass?

In New Zealand, glazing in doors — including bifold doors — is typically required to be safety glass under NZS 4223 and the NZ Building Code. Toughened glass will craze into small, relatively safe cubes when it fails, while laminated glass tends to hold together. If your bifold door was installed to code, it should have one of these safety glazing types. If you're unsure what type of glass you have, a qualified glazier can identify it.

Make the Area Safe Immediately

Your first priority is safety:

• Keep children and pets away from the area.
• If there are loose shards, wear heavy-duty gloves and carefully collect them in a thick cardboard box or newspaper — never a plastic bag that could be punctured.
• Do not attempt to remove the cracked panel yourself unless you have glazing experience. Bifold door panels can be heavy and awkward, and broken glass edges are extremely sharp.
• Apply clear packing tape across both sides of a hairline crack as a very short-term measure to hold the glass together and reduce draughts. This is a temporary fix only.

Secure the Opening

If the panel is badly damaged or missing glass, you'll need to temporarily secure the opening:

• Use a sheet of plywood or polycarbonate cut to size and taped or screwed over the frame opening.
• This keeps the weather out and maintains basic security until a glazier can attend.
• In NZ's variable climate — especially in coastal or high-wind areas — leaving an unsecured opening even overnight can cause further damage to your home's interior.

Can You Replace the Glass Yourself?

Replacing glass in a bifold door is not a simple DIY job for most homeowners. Here's why:

• Bifold door panels often use double-glazed units (IGUs — insulated glass units), which must be factory-sealed and cannot be repaired on-site.
• The replacement glass must meet NZS 4223 safety glazing requirements for door panels — standard float glass is not compliant.
• Bifold door frames (aluminium, timber, or uPVC) require specific glazing beads, setting blocks, and sealants to hold the glass correctly and maintain weathertightness.
• Incorrect installation can void your door manufacturer's warranty and may create issues with your home insurance.

If you are a confident DIYer and the door uses a simple single-glazed panel in a timber frame, it may be possible to source compliant safety glass from a glass supplier and reglaze it yourself — but you must ensure the replacement glass meets the required thickness and safety standard for the opening size. When in doubt, leave it to a professional.

What a Glazier Will Do

A qualified glazier will:

1. Measure the panel accurately, accounting for frame tolerances.
2. Source the correct glass — toughened, laminated, or a new IGU — to meet NZS 4223.
3. Remove the broken panel safely using proper tools and PPE.
4. Install the new glass with correct setting blocks, glazing tape or putty, and beads.
5. Check the bifold hardware (rollers, hinges, pivot pins) while the panel is out, as a cracked panel can sometimes indicate the door has been racked or a roller has failed.

Turnaround time varies — standard toughened glass is often available within a few days, but custom-sized IGUs may take longer to manufacture.

Cost to Replace Bifold Door Glass in NZ

As a rough guide only, glass replacement costs in NZ vary significantly depending on:

Get at least two quotes from local glaziers. You can find qualified glaziers in your area on tradedirectory.co.nz.

Check Your Insurance

Before paying out of pocket, check your home and contents insurance policy. Accidental glass breakage is covered under many NZ policies, sometimes with no excess. Contact your insurer before arranging repairs, as they may have preferred suppliers or require an assessment.

When to Call a Professional

Call a qualified glazier if:

• The panel is shattered or has missing glass — this is not safe to handle without proper PPE and experience.
• The door uses double glazing (IGU) — these must be factory-made and professionally installed.
• You are unsure whether the existing or replacement glass meets NZS 4223.
• The bifold frame or hardware appears damaged alongside the glass.
• The door is part of a fire-rated assembly — fire-rated glazing is highly specialised.

Glazing work in NZ does not fall under the restricted electrical or plumbing trades, but it does require skill, correct materials, and knowledge of the Building Code. For anything beyond a very straightforward single-glaze reglaze, a professional glazier is strongly recommended. Find a local glazier on tradedirectory.co.nz.

Sources & Further Reading

• MBIE Building Performance — NZ Building Code
• Standards New Zealand — NZS 4223 Glazing in Buildings
• WorkSafe NZ — Safe handling of glass
• BRANZ — Glazing guidance
• Consumer NZ — Home insurance tips