Single pane windows are, for the most part, a thing of the past. But there are still older homes that have single pane windows. It is inevitable that at some point a single pane window will be broken. Glazing is a term that describes replacement of a windowpane, or more properly, setting glass in a frame. Single windowpanes were usually held in place in a wooden frame with glazing points (small triangular pieces of metal) and made air and weather tight with glazing putty. Panes were held in place in metal frames with small spring steel glazing clips in place of glazing points.
Removal of the broken pane
- The glazing putty may be cracked or hard and crumbling. Remove it carefully with a razor knife and putty knife.
- If the glazing putty is too hard to remove with a putty knife, you can heat it carefully with a propane torch and scrape away the softened putty.
- Once you have removed the softened putty, slide the edge of your putty knife around the wooden window frame where the glass meets the frame. You can feel the glazing points with the edge of the putty knife, even if you can’t see them.
- Starting at the top of the glass pane, work the glazing points out with the putty knife.
- Finally, remove the broken glass pieces from the window frame itself.
Installation of the new glass pane
- It is imperative that you thoroughly clean the rabbited edge of the window frame where the new glass pane will be seated. If even the smallest piece of debris, like putty or an undiscovered glazing point is left on the edge, when you install the new glass pane it may break. Almost certainly, it will leak when it rains.
- Clean the window frame with a small wire brush or scraper.
- Make sure that the new pane is cut slightly smaller than the actual size of the windowpane opening.
- Set the new pane in place in the window opening.
- Install the glazing points using a glazing point tool. Push the points into the wood far enough to hold the pane in place securely but not too far.
- Purchase a can of glazing putty from the hardware store or home center. Mix the putty thoroughly in case any of the oils have settled out.
- Using a small putty knife, apply the glazing putty to the window frame in front of the glass. The putty should be applied in a thickness equal to the depth of the rabbit cut in the wood or metal frame.
- Trim the glazing putty from the inside edge of the frame rabbit to taper down to the outer edge of the window frame with your putty knife.
- Where edges of the window frame meet from vertical to horizontal, or vice versa, use your putty knife to form a nice forty-five degree joint.
When applying the glazing putty, use enough force on the putty knife to push the glazing putty tightly against the glass and into the joint formed by the glass and the wood or metal frame to make a tight seal. Smooth the glazing putty with your putty knife. You can dip it in a light oil like 3-in-one to make an even smoother, more professional looking joint.
Space the glazing points around the glass pane. Use enough points to hold the pane securely in its frame.
Wait to clean the window pane of oily fingerprints until after the glazing putty has set up completely.
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