How to Repair a Dual Pane Window

Gray or foggy glass between the panes of dual pane insulated windows is an issue that leads many home owners to have their windows completely replaced. The money saved in energy usage reduction can quickly be spent on expensive replacements. You can order sealed replacement panes to replace the damaged glass and make the repairs yourself, adding up to major savings. There are three basic styles of insulated pane: gasket seal, adhesive tape seal and caulk seal. Each has its own repair procedure.

Adhesive Tape and Caulk Seals

Over time, dual pane windows can lose their air tight seal.
  1. Remove the sash from the window. Use a pry bar to pry the stop trim away from the jamb at either side of the window. Lift the sash from the window and release the ropes or springs connected to the top corners of the sash frame. They will either be clipped in place, or set into a special groove.

  2. Lay the sash flat and locate the seam between the glass stop and the frame around the edges of the window. Insert a stiff scraper or the tip of a sharp chisel into the seam and gently pry the stop away from the frame. Repeat this on all four edges of the glass. Lift the original damaged pane from the frame. Pry gently with the scraper if needed to lift the glass out of the frame. Scrape the remaining caulk or adhesive tape from the sash frame.

  3. Apply a continuous line of sealing tape around the lip of the sash where the glass will rest for adhesive tape sealed panes, or a continuous bead of caulk for caulk sealed panes. Position the new glass into the frame. Press it in firmly and make sure the pane presses up against the outside face of the sash frame.

  4. Reinstall the stop around the glass. For vinyl, aluminum or plastic stop, press down firmly with the edge of the scraper to snap it into place. For wooden stop, pull the old nails out through the back to preserve the face using locking pliers and nail in place with ¾ inch brads.

  5. Reattach the sash ropes or springs in the reverse of the detaching procedure. Set the sash back into the window. Pull the nails through the back of the window stop with locking pliers to preserve the face. Realign the stop on the jamb and nail in place with one finish nail every 8 to 10 inches.

Gasket Seal

  1. Remove the sash from the window as described in Section 1. Lay the sash flat and remove the corner screws from two opposing corners. Leave the remaining corners intact to keep the frame square.

  2. Slide the original pane from the frame, separating the frame into two L-shaped halves. Be careful not to tear the seal. Remove the seal from the pane gently.

  3. Install the original seal along the outside edge of the new pane. Pressing it firmly against the edges of the pane. Fit the corner of the pane into one of the sash halves. Fit the remaining half to it and press them together to fit the corner joints. Reinstall the corner screws.

  4. Refit the sash into the window jamb and reinstall the stop molding as outlined in Section 1.

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