You have probably seen a cloudy window in your home or someone else's home. Sometimes, it’s only cloudy when the sun shines on it, or perhaps it looks cloudy all the time. You try wiping it away from both sides of the window, but you discover that the cloudiness is on the inside, between the panes of glass. That cloudiness is the result of a damaged thermal seal, and the inspectors at HomePro Inspections often come across this type of window problem during our home inspections.
A cloudy window with a damaged or failed thermal seal
Thermal Seals
Modern windows typically have two panes of glass, and sometimes three. These windows are designed to be more thermally efficient and are referred to as Insulated Glazing Units (IGU). An IGU consists of two or more panes of glass separated at the perimeter by a thermal seal, with an inert gas such as argon or krypton injected between the panes. The thermal seal is airtight and keeps the inert gas from escaping.
Over time, these seals can fail due to deterioration, damage, improper installation, or factory defects. Once a seal fails, the inert gas can leak away, allowing ambient air to enter the space between the glass panes. The IGU will expand and contract due to temperature changes and exposure to sunlight. This can be likened to a bellows, drawing ambient air in and blowing it out. The ambient air contains moisture that will deposit on the interior surfaces of the IGU. Over time, the moisture builds up on the inner glass surfaces, resulting in a cloudy window.
Moisture condensation between the glass panes of a window
Depending on the extent of the thermal seal leak, we see windows that vary in severity from light to heavy condensation and different levels of fogginess. This is an aesthetic issue, as no one wants to see cloudy windows.
Repairing a damaged thermal seal
The first thing to do is to refer to your window manufacturer's warranty. Many window companies warranty their products with 10- to 20-year or lifetime warranties that may cover partial or complete replacement costs.
If a warranty no longer covers your windows, it’s time to call a door and window specialist. These folks can determine the extent of the damage and recommend a proper course of action for the required repairs.
A complete window replacement is usually unnecessary if the only defect is a cloudy window due to a damaged thermal seal. Many windows are designed with the ability to replace only the IGU. The defective IGU is removed from the window unit and replaced with a new one. This is far less expensive and less labor-intensive.
Diagram of an Insulated Glazing Unit (IGU)
Source: www.thearchitectsdiary.com
Can I fix it myself?
If you have the required DIY skills, you may be able to replace an IGU yourself. There are resources online that can walk you through the process step-by-step. This can save you a lot of money, but there is no room for error. An improperly replaced IGU can result in wasted energy, time, and expenses. If you have an IGU with damaged thermal seals and you’re not sure if you can properly handle the repairs, your best bet is to hire a professional.
Defogging
Although not very common, some companies may be able to defog a cloudy window. This process is done by drilling one or more tiny holes in the glass to remove moisture between the IGU windowpanes. This process can remove the moisture and cloudiness but does not restore the thermal efficiency of the IGU because the inert gas cannot be added back.
Summary
Windows are inspected inside and out during your home inspection. Our home inspectors come across cloudy windows with thermal seal issues quite frequently. In most cases, the home inspector will document these issues as maintenance items. Other than aesthetics, a cloudy window is not a huge concern. It’s still a window doing what a window does; it’s just not as thermally efficient.
At HomePro Inspections, our home inspectors are trained to inspect all areas of the home. Any issues found are documented in your home inspection report and recommended for resolution by yourself or a qualified professional.
Visit our website to learn more or to schedule your home inspection in the Rochester, Owatonna, and Faribault, MN areas. You can contact us today at (507) 202-8942 or use our online “Schedule Now” feature to schedule an appointment.