12 Considerations For Repairing or Replacing Glass in a Dual Pane Window

March 23, 2010

If you have a broken pane of glass in a dual pane window, or if you have a leaking dual pane window, you have two options about how to remedy the situation: repair or replace. Here are some points to consider to help you decide what to do.

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Repairing Broken Glass in a Dual Pane Window

  1. The most important consideration in repairing dual pane windows, whether you are repairing one or both panes of glass, or replacing a whole Insulated Glass Unit (IGU) is to measure accurately.
  2. When measuring to replace a single broken glass pane you will need the measurements of the pane including height, width, and thickness.
  3. If both panes are broken, you will need to measure the dimensions of the glass as well as the spacer.
  4. Working within the overall opening, you may be able to replace thinner glass with thicker by using a narrower spacer.

Repairing a Leak in a Dual Pane Window

  1. Condensation on the inside of dual pane windows can be caused by cracks in the glass or by a leaking seal. If the glass is marred, you will need new glass. If the glass is intact, you will need to repair the seal.
  2. Repairing a leaking seal is somewhat easier than repairing broken glass because there is no need to measure for new glass; the existing glass can be reused. However, care must be exercised when loosening the glass from the seal so as not to break the glass.

Procedures and Tools Required for Repairing Dual Pane Windows

  1. Whether repairing the glass or seal, or replacing an Insulated Glass Unit, you will need to remove the window from the window frame, and you will need to remove the glass from the sash.
  2. Tools and materials needed include a screwdriver, a utility knife with a fresh blade, a putty knife, silicone caulking gel, and if the panes are broken, the replacement glass.


  1. Be sure to remove all finger marks from the inside surfaces of both panes of glass before applying the seal.
  2. Allow 24 hours for the seal to set before replacing the window in the frame.
  3. Vinyl windows, because of the deep set of the glass into the frame are more difficult to repair than are aluminum dual pane windows.
  4. In order to avoid the problems in points nine, ten and 11, consider purchasing an Insulated Glass Unit, rather than repairing the individual glass panes and restoring the seal.

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