How to Remove a Broken Window Pane from a Metal Frame

Removing a broken window pane from a metal frame is a job many NZ homeowners can tackle themselves — but safety comes first. Broken glass is razor-sharp, and working at height adds extra risk. Follow these steps carefully, and don't hesitate to call a qualified glazier if you're unsure.

Safety First

Before you touch anything, gear up properly:

• Heavy-duty leather or cut-resistant gloves — standard garden gloves won't protect you
• Safety glasses or goggles — glass fragments fly unpredictably
• Sturdy closed-toe footwear — no jandals
• Long sleeves to protect your arms
• Lay a drop sheet or thick cardboard on the floor below the window to catch falling shards

If the window is above ground level, use a stable ladder and have a second person to assist. Working at height carries serious risks — refer to WorkSafe NZ guidelines before proceeding.

Identify Your Metal Frame Type

Metal window frames in NZ homes are most commonly one of two types:

Knowing your frame type determines how you remove the glass. Aluminium frames use a rubber gasket or glazing strip, while older steel frames typically use linseed oil putty that hardens over time.

Tools and Materials You'll Need

• Heavy-duty gloves and safety glasses
• Pliers or locking pliers
• Putty knife or stiff-bladed scraper
• Utility knife
• Flathead screwdriver
• Masking tape or duct tape
• Rubbish bag or cardboard box for glass disposal
• Drop sheet

Step-by-Step: Removing the Broken Pane

1. Tape the Broken Glass

If the pane is cracked but still largely in place, apply masking tape or duct tape in a crosshatch pattern over the surface. This holds loose shards together as you work and reduces the risk of pieces falling unexpectedly.

2. Remove Loose Shards Carefully

Using gloved hands or pliers, carefully remove any large loose pieces of glass from the frame. Work from the top of the pane downward, placing shards directly into a sturdy cardboard box or thick rubbish bag. Never drop glass — lower each piece gently.

3. For Aluminium Frames — Remove the Gasket or Glazing Strip

Aluminium frames hold glass with a rubber gasket (also called a glazing bead or rubber seal) that clips or presses into a channel around the frame.

• Use a flathead screwdriver to gently prise the rubber gasket out of its channel, starting at a corner
• Work around the perimeter, pulling the gasket free
• Some aluminium frames also have removable aluminium beading (thin strips screwed or clipped in place) — unscrew or unclip these first
• Once the gasket and/or beading is removed, the remaining glass should slide or lift free

Keep the gasket if it's in good condition — you may be able to reuse it with the new pane.

4. For Steel Frames — Remove the Old Putty

Older steel-framed windows use hardened glazing putty to seal the glass into a rebate (a small groove or ledge in the frame).

• Use a putty knife or stiff scraper to chip away the old putty from around the perimeter
• Old putty can be very hard — a heat gun on a low setting can soften it, but take care not to overheat the frame or surrounding surfaces
• Small glazing sprigs (tiny metal pins) may be embedded in the putty to hold the glass — remove these with pliers
• Once the putty is cleared, the remaining glass can be lifted out

5. Clean Up the Frame

Once all glass is removed, clean the rebate or channel thoroughly:

• Remove all old putty, gasket remnants, and debris
• For steel frames, check for rust and treat with a rust converter if needed before re-glazing
• Wipe the channel clean and dry before fitting new glass

6. Dispose of Broken Glass Safely

Wrap glass shards in several layers of newspaper, place in a sturdy box, and label it "BROKEN GLASS" before putting it in your general rubbish bin. Check with your local council if you have a large quantity — some councils have specific requirements.

Measuring for a Replacement Pane

Measure the opening (rebate) width and height carefully, then subtract 3–4 mm from each dimension to allow for clearance. Take your measurements — and ideally a piece of the old glass — to a glazier or glass supplier. They can cut a replacement pane to size. Standard clear float glass is the most common replacement, but check whether your window requires safety glass under the NZ Building Code (particularly for low-level glazing, bathrooms, or near doors).

When to Call a Professional

Call a qualified glazier if:

• The window is above ground level and you're not confident working at height
• The frame is warped, corroded, or damaged and needs repair before re-glazing
• The window requires safety glass (toughened or laminated) — this is a Building Code requirement in certain locations and must be correctly specified
• You're dealing with double glazing — sealed double-glazed units cannot be repaired DIY and must be replaced as a complete unit
• You're simply not comfortable handling broken glass

A licensed glazier will have the right tools, glass, and knowledge of NZ Building Code requirements. You can find qualified local glaziers on tradedirectory.co.nz.

Sources & Further Reading

• MBIE Building Performance — NZ Building Code
• WorkSafe NZ — Working Safely
• BRANZ — Building Research
• Licensed Building Practitioners
• Bunnings — Tools and Glazing Supplies
• Mitre 10 — Hardware and Safety Gear