What Window Condensation Really Means
Not all window condensation is a problem – sometimes it’s a good thing. Here’s how to tell what causes window condensation or fogging, and what to do about it.
What causes window condensation?
Window Condensation occurs when moisture in the air settles on a cooler surface. We see condensatin happen normally every day, in situations like:
- Steam from your shower condensing on your bathroom mirror
- Humid air condensing on your glass of iced tea on a hot day
- Eyeglasses fogging up when you walk into a warm house on a cold day
Condensation isn’t caused by glass; the glass is simply the landing place for moisture in the surrounding air.
Your home’s windows are another cool surface that allows for condensation.
And with two panes of glass in most windows, including Improveit’s Performax54 windows, you might see condensation on the room-side of the window, on the window glass on the exterior of your home, or possibly between the panes, depending on the conditions.
Is Condensation On Windows Bad?
More often than not, condensation or fogging on your windows does not indicate a problem with your windows. In some cases, it may actually indicate that your energy-efficient windows are doing their job! Identifying the cause of window condensation can also help you manage your home’s performance and energy efficiency.
Here are three scenarios to watch out for:
Window Condensation from Excess Indoor Moisture
The next time you notice window condensation or fogging inside your home, swipe your finger across the foggy area. If the glass feels wet and your finger leaves a trail, you have moisture collecting on room-side of your window glass. This is an indication that your home’s indoor humidity is too high.
What does that mean? In some cases, excess indoor humidity is normal. But constant high humidity can lead to mold growth on wood framing and drywall, and cause poor indoor air quality, both of which can lead to health problems.
Here are a few causes of excess indoor humidity and what you can do about it:
This condensation is normal and temporary; it will evaporate on its own as the space returns to a normal humidity level. Running an exhaust fan in the bathroom or the range hood in your kitchen can keep this condensation at bay.
During dry winter months, it’s common to run a humidifier in your home. Some HVAC systems even have offer whole-house humidification. The ideal indoor relative humidity level is 30-50% depending on the outdoor air temperature. Refer to your humidifier’s manual for the best way to set and run the unit to achieve this.
Outdoor air finds its way into your home through all kinds of gaps and cracks, especially around older, uninsulated windows and doors. When outdoor humidity levels are high, that excess moisture enters your home with the rest of the outdoor air. If you notice indoor condensation on windows that aren’t otherwise affected by steam or humidity from other sources, it may be time to air-seal your home or replace your windows. (Take our one-question quiz to see how much longer your current windows will last.)
Excess Outdoor Moisture Causing Window Condensation
If the same swipe test reveals condensation on the exterior side of your windows, it’s a positive indication that your windows are working the way they should. The best dual-paned, energy-efficient windows are designed to reduce heat transfer through the glass. What does that mean?
Just like in your steamy bathroom, moisture in outside air will condense on cooler surfaces. If the surface temperature of your window glass is lower than the dew point, you’re likely to see condensation on the outside of the window. This means your energy-efficient windows are keeping the warm air inside your house, and not transferring it to the exterior pane of glass – exactly how they should work! As the sun warms the exterior of the window, the condensation will evaporate.
Condensation Between Window Panes
Here’s the tricky one. If you try the swipe test and can’t feel or remove the condensation from the surface of your window glass, the problem could be moisture trapped between the window panes. Unfortunately, this problem has no easy solution.
As we mentioned, most energy-efficient windows have two panes of glass. The space between the panes is filled with an insulating gas such as argon. Over time, the seals keeping the argon in place can deteriorate. Most windows seals break within 5 to 7 years.
Here are the three things that happen next:
FIRST: The argon gas escapes. The reduces the window’s energy efficiency because it can no longer keep heat from moving through the glass.
SECOND: Surrounding air fills the void. As the insulating gas escapes, it’s replaced by “regular” air, which contains moisture, dust particles, mold spores, etc.
THIRD: Moisture condenses on the interior face of the glass. This causes inaccessible fogging and condensation that can’t be removed.
Once seals break, the problem will only get worse and lead to more issues:
- Excessive fogging or condensation will make it impossible to see through the window glass.
- Moisture can cause rusting of internal metal components, such as metal window spacers
- When the window gets hot, trapped moisture can expand, threatening the structural integrity of the glass, sash and window frame.
How to Fix Window Condensation
Once moisture starts condensing between the window panes, there’s no easy or inexpensive way to remove it. If the fogging is minimal or unobtrusive, you can try sealing the edge of the glass with clear silicone. This might help prevent more moisture from getting in. However, doing this could void the warranty on your windows, and does nothing to recover the lost energy efficiency.
The only option to eliminate condensation trapped between your window panes is to replace the affected sash. A new sash with an intact seal will help the window perform at its best and maintain the structural integrity of the entire window unit.
What to Do if You See Condensation Between Window Panes
If your windows are already experiencing condensation between the glass, reach out to your window installer or manufacturer to discuss replacing the sash. Unfortunately, broken window seals are usually not covered by window warranties, so the replacement can cost several hundred dollars for a sash by itself, or much more for an entire window replacement, including the cost of labor.
Improveit window customers don’t have to worry about this extra expense! All Improveit Performax54 windows come with a complete, transferable lifetime warranty that covers everything – including broken seals. Our No Seal Failure Guarantee means that if any window installed by Improveit experiences a broken window seal, we’ll solve the problem at no cost to you.