Window Repair

What can you do if your window to the world is broken? You can often easily fix it! This Fix-It Guide on window repair tells how a window works, what often goes wrong, how to identify a window problem, and what parts and tools you will need to fix it. It then gives instructions for how to clean and lubricate a window, how to service a casement window or skylight opening mechanism, how to weatherstrip a double-hung window, and how to replace a window pane. After your window repair, you may also need paint repair. If you need skylight repair, also see roof repair.

How Does a Window Work?

A window is an opening in a wall of a building for admission of light and air. A window typically has casements or sashes that contain transparent glass or plastic. Many newer windows are double paned, offering increased energy efficiency.

Window Repair

Popular types of windows.

The main types of windows are double hung, casement, awning, sliding, and stationary. Double-hung windows are the most common in homes. A double-hung window is designed so that the lower portion of the window opens up in front of the upper portion. A casement window has hinges on one side that allow the window to swing out. An awning window is hinged hear the top and swings out at the bottom so it can be open even in rain. A louvered window is similar to an awning window except it has more panes and hinges. A sliding window slides from side to side on metal or plastic rollers that sit in channels along the top and bottom of the window frame. A stationary window does not open.

What Can Go Wrong with a Window?

The two most common problems with windows are sticking casements and broken glass. Casement window mechanisms get dirty and sometimes break. Older windows often let in too much air from outside and need weatherstripping. The biggest problem with skylights is leaks.

How Can I Identify a Window Problem?

  • If a window sticks, cleaning and lubricating (see below) may be all it needs, especially if it has an aluminum frame.
  • If a casement window or skylight opening mechanism does not operate easily or at all, you can replace it (see below).
  • If a window lets drafts in, you can add weatherstripping (see below).
  • If a window pane breaks, you can replace it (see below).
  • If a double-pane window is broken or the airtight seal between panes has moisture in it, the window will probably require professional repair, but it may still be under warranty.
  • If a skylight leaks, check for leaks around the flashing (see the Roof Fix-It Guide) and use roofing cement to plug any cracks where the roof and skylight meet.

What Do I Need for Window Repair?

Replacement parts are available from glass shops, hardware stores, home centers and other local retailers. The tools you will need to fix a window include these:

  • Hammer
  • Nail set
  • Silicone lubricant
  • Paraffin wax
  • Mineral spirits
  • Screwdrivers
  • Roofing cement
  • Weatherstripping
  • Small wire brush
  • Putty knife or chisel
  • Vacuum
  • Glazing points
  • Glazing compound


For safety, wear leather work gloves when handling broken glass.

What Are the Steps to Window Repair?

Clean and lubricate a window:

  1. Clean the bottom, side, and top tracks or channels with a rag, small wire brush, and/or vacuum.
  2. If rollers, glides, and other small parts are dirty, clean them with mineral spirits.
  3. Spray the tracks with a silicone lubricant or rub them with paraffin wax, cleaning up any excess.

Service a casement window or skylight opening mechanism:

  1. Open the window halfway and remove the screws that hold the mechanism to the frame or the sill.
  2. Remove the extension arm from the sash by sliding it along the sash until the tip reaches the access slot.
  3. Push down the extension arm and pull the tip through the slot.
  4. Pull the mechanism out of the slot, loosen the handle setscrew and remove the handle.
  5. Check the teeth under the handle and replace the operating mechanism if the teeth are stripped.
  6. Reinstall and test the mechanism.

Weatherstrip a double-hung window:

Fix-It Tip

Weatherstripping requires a clean surface for it to adhere. Before applying self-stick weatherstripping, wash, rinse, and dry the surfaces to which it will be applied.

  1. Cut a length of weatherstripping equal to the width of the window sash.
  2. Remove the backing and apply the weatherstripping to the bottom of the lower sash as directed by the manufacturer.
  3. Cut two lengths of weatherstrip an inch longer than the height of the lower sash.
  4. Apply those strips to the lower half of the interior side channels in the window frame as directed by the manufacturer.
  5. Drop the sash halfway so its bottom rail is exposed.
  6. Apply the weatherstrip to the inside edge of its bottom rail.
  7. Lower both sashes and apply weatherstrip to the top of the sash.
  8. Cut two lengths of weatherstripping an inch longer than the height of the upper sash, and apply the strips to the upper half of the exterior side channels in the frame.

Replace a window pane:

  1. Carefully remove the broken glass from the pane.
  2. Use a putty knife or chisel to remove any putty left in the channel.
  3. If you are installing glass in a wood window pane, first clean the channel and coat it with linseed oil. Apply a small amount of glazing compound to cushion the glass.
  4. Place the new glass in the pane and carefully seal it into the glazing compound.
  5. Place a glazier point every 3 inches along the pane to retain the glass.
  6. Apply a small amount of glazing compound around the pane to hold the glass to the wood. If you are replacing glass in an aluminum frame you will use a rubber gasket (available from hardware stores) to hold the glass in place.
  7. Remove any excess compound with a putty knife. Allow the compound to dry for seven days and paint (see the Paint Fix-It Guide) as needed.

Fix-It Tip

Clean a glass skylight in the same way you clean any glass window. Clean a polycarbonate plastic skylight with a mild soap or detergent solution. Use a weak ammonia solution to clean an acrylic plastic skylight.