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How to Tell If Your Window Seal Has Failed

Nearly all modern windows sport a type of sealed glazing. Commonly known as IGUs or insulated glass units, these windows are also referred to as insulated windows or thermopanes. After quite some time, the seals on IGU windows may deteriorate and eventually fail, compromising the insulating ability and diminishing the transparency of the window unit. In this article, Renewal by Andersen® of Long Island, a leading provider of energy-efficient sliding windows, explains how you can tell if a sealed window has failed.

Tell If Your Window Seal Has Failed

Composition of IGU Windows

Only two or three panes of glass assembled together form an IGU. The glass panes of these windows are separated by a specific kind of spacer material and sealed tightly at the edge. The space between glass is often filled with inert gas, either argon or krypton. This innovative technology minimizes heat transfer so that IGU windows remain airtight, keeping your home cool in the summer and warm in the winter.

How Seals Fail

Over time, the inert gas inside sealed windows can leak out, prompting moisture from outside air to trickle into the space between panes. It has been said that even when an IGU is perfectly constructed, the gas will escape at a rate of approximately one percent per year, and that rate is much quicker when the sealed window installation unit is poorly made.

How to Determine Seal Failure

Knowing if the seals of your windows have failed is not always a cakewalk. Here are some tips:

•  Clean the glass. Look for fogging between panes. Be sure to thoroughly clean the interior and exterior surfaces of the window to be certain that you are not looking at external moisture.

•  Look for distortion. Stand at a distance away from the window unit and see if the glass appears distorted in the center. It likely indicates that seal failure has occurred.

Renewal by Andersen of Long Island is a premier source of energy-efficient replacement windows and doors. Our team is committed to providing a cozier and more pleasant living space for you and your family through industry-leading products and expert installation skills. Call us today at (631) 843-1713 or fill out our contact form to set up an appointment. We work with homeowners in Massapequa, New York and the surrounding areas.


"I was very impressed with Renewal by Andersen. They showed up in time and we received several follow up phone calls as the installation was being done as well as the sales representative stopping by to check in on the installation. The delivery/ installer was very professional. I would highly recommend Renewal By Andersen."

February, 18

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