Removing window glass

Although double glazing is widely used in modern houses, there are still some single glazed windows around and this article deals with removing broken glass in these single glazed windows.

Safety when working with glass:

Pieces of broken glass can be sharp and dangerous, so wear suitable safety protection (thick gloves and eye protection) and a garment with long, thick sleeves.

Also consider your surroundings; if the window is at first floor (or above), it is often better to remove the sash so it can be worked safely - if the window is non-opening, this won't be an option so you will need to take additional precautions to prevent anyone from walking underneath while you are working.

When working with glass at height, always use a work platform, don't try to work from a ladder.

Removing the old glass.

The amount of damage to the original glass will affect how it can be removed:

  • Removing glass by handIf the original glass is shattered, most of the large pieces of glass should be quite easy to remove from the frame by gripping one broken piece at a time and working it backwards and forwards through the frame to loosen the grip of the putty.

    Start by removing the pieces of glass from the top of the frame and work down to the bottom - this will remove the danger of shard dropping down on your hand as you work.

    Once each piece of glass is loose, it can be lifted out.

    Any small pieces left around the frame can be carefully gripped with piers and worked backwards and forwards to remove them.

  • If the glass is only cracked, the pane will need to be broken (don't try to remove the old glass by removing the putty). You first need to decide which side of the window to work from.
    • Use a glass cutter to score the glass about 50mm (2 inch) in from the frame. Also score diagonally across the glass between the corners.
    • Apply some masking tape across the window (to help hold the pieces in place).
    • Place thick plastic sheeting across the window frame on the opposite side to that scored by the glass cutter - fold it under the sash and attach it to the lower edge of the frame - this will retain the pieces of broken glass so they can more easily be collected/removed.
    • Give the glass a few sharp hits with a hammer around the window on the scored side adjacent to the scored lines (away from the frame) - the glass should break more or less along the scored lines. Carefully lift out the larger pieces of broken glass. As some glass is removed, it will become easier to grip those pieces left and to wriggle them to loosen them from the putty or break them at the scored lines.
    • Any small pieces left around the frame can be carefully gripped with piers and worked backwards and forwards to remove them.

Cleaning the rebates.

Wooden frames:

Chipping out the puttyChop away the remaining putty from the rebates using a glazier's hacking knife or old chisel.

You will come across glazing sprigs (small, headless nails used to hold the glass) in the putty, pull this out using pincers.

Clear the putty from both sides of the rebates, take care not to damage the timber sides of the rebate. If necessary, use a rasp or sandpaper to clean off any small last remains of putty.

Seal the timber before reglazing using either a wood primer paint or a 50/50 linseed oil/turpentine mixture.

Metal frames:

Removing the old putty is more or less the same as for wooden frames, the main difference is that clips are used to hold the glass rather than sprigs - try not to damage these clips so they can be reused.

With a steel frame, remove and treat any signs of rust in the rebates.

Apply an appropriate primer to the rebate surfaces before reglazing.