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What Causes Discoloration in Double-Pane Windows?

Double-pane windows, also known as insulated windows, help you save on your energy costs by limiting the amount of heat that can pass through into your home. Sometimes, though, you might notice discoloration on your windows. Here’s what causes this discoloration and what can be done to fix it.

What Causes Discoloration in Double-Pane Windows?

How Double-Pane Windows Work

Every home has an energy enclosure, which is comprised of the attic, exterior walls and fenestrations (entry doors, skylights and windows). These components are insulated in one way or another. The walls may have batt or expanding foam insulation, and the attic may have loose-laid or blown-in insulation while entry doors may have foam cores. A well-insulated energy envelope should maintain consistent indoor temperatures, which should make the indoor space more comfortable and energy-efficient.

Windows (and patio doors) are mostly made of glass, a naturally conductive material. The aforementioned types of insulation are not suitable because they’re opaque. The solution is double-pane windows. Inserting a space between interior and exterior glass surfaces minimizes heat conduction through the glass. When set into an insulated sash or frame, double-pane windows complement the rest of the energy envelope in providing comfortable indoor spaces. This has proven to be so effective that all Renewal by Andersen® replacement windows feature double-pane glass as a standard component.

Double-Pane Window Discoloration

Indoor moisture problems can cause discoloration on double-pane windows. It may appear as black or similarly dark-colored streaks on the window surface, but the cause is the same. Fortunately, window discoloration is preventable. You simply need to control your home’s relative indoor humidity. Most residential HVAC systems already have humidifier/dehumidifier systems built in, which means you only need to consult your HVAC technician on how to adjust its settings.

Repair or Replace?

How about windows that are already discolored? The first thing you should check is your window warranty coverage, especially if the window is still relatively new. You can also ask your window contractor if repairs are possible as some double-pane glass assemblies are designed as a single unit. If the windows will ultimately require replacement, ask your replacement window provider if an insert window replacement is possible. Instead of replacing everything, insert window replacements retain the original frame, which may cost less and take less time to install.

Renewal by Andersen of St. Louis is your leading provider of replacement windows. Give us a call at (314) 332-2364, or fill out our contact form. We serve customers in Chesterfield, MO and nearby areas.

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