The proper technique for replacing a broken window pane depends on the type of window you have. Traditional divided-light windows have individual panes set into a framework of wood muntin bars and are secured with glazier’s points and putty called glazing compound. Most older windows have a similar construction. Modern divided-light windows often have a single, large pane with a faux muntin frame that overlays the glass, or in some cases is installed between the glass panes. Replacing panes in sealed, insulated windows should be done by a professional to maintain the window’s thermal performance.
To replace a glass pane on a traditional window, first remove any shards of broken glass, then follow the steps below, being careful not to break glass as you work.
Improving Older Windows
You don’t have to replace your older windows to save hundreds on energy costs. Over time, glazing putty can crack, which allows for great thermal transfer between inside and out, bumping up your heating and cooling costs in the process. Simply re-glazing existing window panes (and re-caulking the window frames) in older homes can radically affect energy efficiency and save you a bundle of cash with very little effort.
How to Replace a Glass Pane
Step 1 Soften old glazing putty with a heat gun set on medium or low, being careful not to scorch the wood. If the heat doesn’t work, coat the compound with linseed oil and let sit. The oil will eventually soften the putty.
Step 2 Remove softened putty with a putty knife. Repeat in small sections until all the putty is removed, and remove any old glazier points still in the frame. Scrape the edges clean and coat the bare wood with primer.
Step 3 Measure the inside dimensions of the frame and order a replacement pane about ‘Is” smaller in width and height than the opening. Make a bed for the pane with a thin bead of glazing putty inside the frame, and seat the glass securely in it to ensure a good seal. Drive glazier’s points into each side of the frame with a putty knife blade to secure the new pane.
Step 4 Lay another, thicker bead of putty along the pane’s edges, then smooth it into a clean bevel with a putty knife. Clean off any excess and let dryas directed. Prime and then paint the putty and frame edges to match the rest of the window.
