How to Replace a Broken Single-Pane Window

Two windows with a broken window pane in each window

1) Prep the area (remove glass, old glazing and caulk)

2) Measure and test-fit the new glass

3) Install the new glass pane (with caulk and glazing points)

4) Apply glazing

Broken windowpane? Replacing single-pane window glass is easy with a few tools and easy-to-find materials from your local hardware store. Check out these step-by-step instructions for replacing single-pane window glass that is held in place with glazing.

Window Pane Replacement Tools & Materials

  • Putty knife
  • Pliers
  • Glazing
  • Caulk
  • Leather gloves & eye protection
  • Carpenter’s knife
  • Glazing points
  • Sandpaper

Replacing a Single-Pane Window

1) Prep the Area – Wear leather gloves while you remove the broken glass. Use a putty knife to scrape away the old glazing, which is pliable putty that hardens to hold the windowpane in place. If it’s difficult to remove, use a heat gun to soften the old glazing compound. Use pliers to remove old glazing points (if they were used). Smooth out rough edges or remove old caulk with sandpaper.  

2) Measure and Test-Fit the New Glass – Once the old glazing material is removed, you should have a nice, clean opening for the new glass. This is a good time to measure the opening to find the correct size of glass pane replacement. Your local hardware store will be able to cut a glass pane that is slightly smaller than this opening – about 1/8 inch less than your measurements. Take a shard of old glass with you to match the thickness and type. When you have your new pane, dry-fit it in the frame to be sure it’s snug.

3) Install the New Glass Pane – Lay a small bead of latex caulk around the perimeter of the opening for a good weather seal. Install the new glass pane, and insert glazing points into the frame to hold the glass in place. You should only need two points on each edge for standard sizes of window glass.

4) Apply Glazing – Use a putty knife to smear the new glazing compound around the perimeter of the glass. Glazing compound also comes in tubes and can be applied like caulk. Make sure it fills all cracks and gaps around the glass for a weather-tight seal. If you’re working with an oil-based glazing compound, heat the container up in a bowl of warm water so it’s easier to work with. Latex-based glazing compounds dry quickly, so don’t wait too long before smoothing it out.

Smooth out the glazing compound with your putty knife. Once it’s smooth, cut or drag away the ridge of excess glazing compound. Oil-based glazing compounds need a few days to set and dry before the glazing is firm and can be painted. Latex glazing compounds dry quicker and are ready for paint after a few hours. Follow the directions on the packaging for cure times.

Hire the Wndow Pane Repair Experts

Replacing and glazing a single-pane window is easy, but it’s a serious time commitment if you have to repair a lot of windows. Glass Doctor can replace single-pane windows for you or upgrade you to more energy efficient IGUs. Call 833-974-0209, or schedule an appointment online for professional glass and window repair.

Glass Doctor is here to help you decide whether to repair or replace your windows. But when does it make sense to replace other broken household features and items instead of repairing them? Mr. Handyman can help you decide if you should repair or replace certain items around the house. Mr. Handyman is a trusted home service provider in Neighborly's network, so you can expect great advice and service from experts who care.