My Double-Pane Windows Leak Air

Identifying Double-Pane Windows

• Double-pane or double-glazed windows are composed of two parallel panes of glass, with a small area of gas between. The sandwiched space between provides insulation, serving as a buffer between the indoor and outdoor temperatures. In some cases, the space is filled with a particular gas, such as argon, while in other cases it is simply filled with air.

Double-Pane Windows and Air Leaks

• Just a pinhole-sized opening in either pane of your double-pane windows can jeopardize the window's ability to insulate your home efficiently. Double-pane windows, like single-pane windows, typically develop leaks around their edges, where the window pane meets with the window frame. In the case of a double-pane window, it's possible for a leak to form along either the outer or inner pane, so leak detection can take somewhat longer. Other common leakage spots include the area where one section of the window meets another or where the window frame meets the wall.

Remedying Air Leaks

• To repair a window that leaks air, you first need to identify the source of the leak. Hold a lit candle next to the window, slowly passing it along the edges of each window pane and along each side of the window frame. Wherever your window has an air leak, the moving air will cause the candle flame to flicker or even go out. Once you identify the leaks, use weather stripping or foam sealant to close the gaps. Once the stripping or sealant has set, repeat the candle test.

Follow-Up Measures

• After repairing any leaks in your double-pane windows, it's likely that you'll see a considerable improvement in your heating or cooling bills. If the cost of heating and cooling your home is unchanged, consult with an contractor who specializes in energy-efficient building. Switching to double-pane windows with low-e glass, low-solar-gain windows or high-performance glass may improve your energy efficiency even beyond eliminating air leakage. Replacing old windows may also reduce the risk of future air leaks, common along old window frames.