How To Replace A Single Pane Of Glass In A Metal-Framed Window

Anything from a flying baseball to a confused bird can wreak havoc on your windows. If a single pane of glass gets broken in your metal-framed window, you should fix it right away not only for appearance's sake, but for safety sake as well. The good news is you don't have to replace the whole window. Here are some tips on replacing a single broken glass pane in metal-framed windows.

Make Preparations

To make this repair, you need:

  • replacement glass
  • rope
  • towel
  • masking tape
  • steel wool pad or cloth
  • fine-grade sandpaper
  • hammer
  • safety gloves and glasses
  • putty knife
  • paper bag
  • tape measure
  • window glaze putty

Rope off the area to prevent injuries from someone walking barefoot in the area, or place tarp.Wearing safety gloves and glasses, remove all pieces of broken glass off the floor, and place the broken pieces in the paper bag.

For a window pane with a crack, make a criss-cross with masking tape over each side of the glass to keep it from shattering, cover the glass with a towel. Tap the glass with a hammer, remove glass, and discard it.

Remove Old Putty and Spring Clips

Scrape any old glazing putty left on the window frame with the putty knife or screw driver, using a heat gun, if needed, to soften the putty. If the frame has rusty areas, clean dirt with steel wool pad or cloth, sand the spots with fine grade sandpaper to smooth the surface.

Paint the frame with rust-inhibiting paint, and let it dry. Metal window frames are secured with clips. Remove the clips with pliers, or pinch them on the end to disengage them, and replace the springs if they are broken.

Insert the New Glass

Get measurements of the frame opening, and deduct ¼ from the measurements to allow for clearance. Use these measurements when you buy the replacement pane so the glass can be cut to the right size. Pinch off some window glaze putty, and roll it in your hands until it forms a ¼ inch thick rope. Press the putty rope with the putty knife into the seam between the window frame and window pane beginning at the lower edge, and working around the perimeter.

Insert the springs in the holes, and carefully place the new glass in the frame grooves, pressing it down on the putty. Tilt the knife at a 45-degree angle, and move it from corner to corner to smooth the putty, scrape excess putty, and let it dry for several days. 

Your metal-framed window should look as good as new. If you don't trust your window installation skills, or you have seriously damaged windows, call a window replacement service.