How to Replace a Broken Window Pane

Remove the old glass and glazing putty, measure and cut new glass to fit, then secure it with fresh glazing compound and glazier points.

  1. Clear Broken Glass First. Put on safety glasses and work gloves. Carefully remove loose glass pieces by hand, then use pliers to wiggle out stubborn shards stuck in the putty. Work from the outside of the window frame. Tape newspaper inside the window to catch falling glass pieces.
  2. Strip the Frame Bare. Use a putty knife or chisel to scrape away all the old, hardened glazing compound from the window frame. Pull out any metal glazier points with pliers. Sand the bare wood groove lightly and wipe clean with a damp cloth. If the wood is bare, apply a thin coat of linseed oil or primer to prevent the new putty from drying out too quickly.
  3. Get Your Measurements Right. Measure the opening width and height at multiple points, then subtract 1/8 inch from each dimension to allow for expansion. Take these measurements to a glass shop or hardware store. Standard window glass is usually 3/32 inch thick, but double-check by measuring a remaining piece of the old glass.
  4. Lay the Putty Bed. Knead the glazing putty until it's pliable and warm. Roll it into thin snakes about pencil thickness and press it into the groove around the entire frame. This creates a bed for the new glass to sit on and prevents rattling.
  5. Set the New Glass. Carefully position the new glass into the frame, pressing it gently into the putty bed. The glass should sit evenly with consistent gaps on all sides. Don't press too hard or you'll push out all the bedding compound.
  6. Lock It in Place. Push glazier points into the wood frame every 6 to 8 inches around the perimeter. Position them against the glass surface and tap them in with a putty knife or small hammer. The points should be flush with the glass surface but not crack it.
  7. Seal the Perimeter. Roll more glazing putty into ropes and press it around the entire perimeter of the glass. Use a putty knife held at a 45-degree angle to smooth the compound into a neat, angled bead that covers the glazier points. The putty should extend from the glass surface down to the wood frame.
  8. Wait, Then Paint. Clean any putty smears off the glass with a razor blade. Allow the glazing compound to cure for at least a week before painting. Once cured, apply primer and paint to match the existing window trim.