How to Replace Broken Window Glass

W**indows** are the eyes of your home, and a cracked or shattered pane is an immediate eyesore and a major security concern. Replacing a single pane of glass is a manageable task that saves you the cost of replacing the entire sash, provided you work with patience and respect for the sharp edges you are handling. Success in this project lies in the preparation. Removing the old, hardened putty without damaging the wood sash is the most critical step. Once you have a clean surface and a precise measurement, installing the new glass is straightforward work that restores both the insulating value and the integrity of your frame.

1. Protect Yourself First. Lay a heavy drop cloth below the window to catch falling shards. Wear thick, cut-resistant gloves and eye protection before you touch the broken glass.
2. Strip Away the Old. Use a pair of pliers to carefully pull out the shards from the sash. Once the large pieces are gone, use a stiff putty knife to scrape away the old, hardened glazing putty from the wood.
3. Free the Metal Tabs. Locate the small metal glazing points holding the glass in place. Use your putty knife or a flat-head screwdriver to pry them out of the wood frame.
4. Get the Numbers Right. Measure the width and height of the opening inside the sash rabbet. Subtract 1/8 inch from both measurements to ensure the new glass fits without binding.
5. Lay the Foundation. Roll a thin 'snake' of glazing putty and press it into the bottom of the frame where the glass will rest. This creates a cushion and a seal for the new pane.
6. Seat and Secure. Press the new glass gently into the bedding until the putty oozes slightly. Secure the glass by pushing metal glazing points into the frame every 4 to 6 inches.
7. Polish the Seal. Roll more putty into a long rope, press it into the gap between the glass and the wood, and smooth it at a 45-degree angle with your putty knife. Allow it to cure before painting to match the sash.