Window condensation is a fairly common occurrence, and one every homeowner has observed at some point. It can range from barely noticeable to covering the entire pane. This can certainly be an annoyance, is it a cause for concern? That depends on where the condensation is. Droplets that form on the inside or outside surface of a window are a result of humidity levels and glass temperature. This type of condensation is harmless. There’s not much that can be done to prevent outside window fogging unless you want to make the temperature inside your home the same as the temperature outside your home. For most people, that’s an extreme solution to a very minor issue. Condensation on the inside of a window is the result of high humidity levels. In colder climates, this is more noticeable in the winter. In southern states, it’s more common in the summer when HVAC units are running 24/7. Investing in a dehumidifier, occasionally opening the windows to release moist air, and upgrading weatherstripping can help reduce inside window condensation. Although condensation on the inside or outside of window glass is nothing to worry about, that’s not the case with condensation inside the windows.
Why Windows Fail
First a caveat. It’s obviously not possible to have between-the-panes condensation with a single-pane window. Everything discussed here applies to double- or triple-pane models. So, what causes condensation inside the glass? It’s a one-two punch of seal failure followed eventually by desiccant saturation. Let’s examine each in a little more detail.
All double- and triple-pane windows have seals to protect against moisture incursion. In fact, most premium windows have two sets of seals. The inside seal is between the glass panes and the outside seal is between the frame and the sash. These seals are usually made with a flexible caulk that is pliable when first installed. This means they can flex when the window frames expand or contract due to normal daily heating variations, thus preventing gaps from forming. As window seals age, however, they begin to stiffen, which inevitably leads to seal failure. Despite its rather ominous sound, seal failure is not something that greatly affects window performance. At least, not at first. The amount of moisture infiltration is small, and modern windows have a backup component to compensate: desiccant.
Window desiccant is an absorbent material installed between the glass. Its purpose is to draw excess moisture from the atmosphere between the panes (in energy-efficient windows, that’s either argon or krypton gas used as fill) and “lock” it away. Desiccant can be in the form of clay, silica gel, or aluminosilicate depending on the type of window, with clay being the least expensive and aluminosilicate the most. Window desiccants can soak up a lot of moisture and usually last for years. But they are not a permanent solution and will become saturated at some point. When this happens, they can no longer prevent condensation from forming inside the glass.
When you take into account both the seals and desiccant, by the time you notice condensation the window’s primary and secondary moisture defense systems have failed. And if the inside seals are broken, chances are the outside seals between the frame and the sash are as well. This can allow moisture inside your house, either in the form of vapor (humidity) or leaks.
How to Eliminate Condensation Between Window Panes
In some cases, between-the-panes condensation can be fixed with a window restoration. This involves removing the glass and recaulking the seals. This process is mostly used on historic windows that are of significant architectural value. For most homeowners, the better option is usually to upgrade the windows entirely with new models that are more energy efficient and easier to operate while requiring minimal maintenance.
At The Window Depot, we are the company to turn to for all your window replacement needs. We proudly offer options from PGT, Simonton, and Custom Window Systems (CWS). If you are a homeowner in the Tampa Bay, Sarasota, or Venice area, we’ll be happy to provide a complimentary consultation to review all of the windows we offer and install. You can also visit our showroom in Palm Harbor to see examples of our models.