Window Condensation

Condensation on My Windows: What’s the Cause?

Condensation is one of the most frequent window issues homeowners face. Whether you call it condensation, moisture, sweating, fog, frost, or ice, it’s all the same thing. But why does it happen and how do you stop it?

Unfortunately, condensation can be caused by a number of different factors, and it’s next to impossible to come up with a one-size-fits-all solution. But here are a number of different situations that may help you zero in on the problem.

Condensation on the Outside

Let’s start with the good news. Frost or ice on the outside of your windows is not a problem. It’s a sign that your windows are doing the job of keeping much of the cold air outside, where it belongs. The windows are warmer than the outside temperature and cause frozen condensation.

Condensation on the Inside

It’s a different story if there’s condensation on the inside of your home, particularly if it’s on your windows.

Condensation is simply what happens when the warm, moist air inside your home contacts your cold windows. The moist air cools upon contact and changes into moisture, or even frost or ice, on your windows. In older, poorly insulated homes, moisture can even develop on walls. But it usually settles on your windows because they’re the coolest part of a room.

Condensation problems are typically much worse with older windows. Glass units over 10 years old were not built as well as they are today. Older sealed glass systems have very poor insulating value. As a result, the inside surface of the windows is much colder, causing worse condensation problems. Old windows need a lot of warm airflow to help warm them. This is why hot air registers are usually found under windows.

Condensation may not be a major problem if it only happens once in a while, like during a real cold spell. But if you’re faced with moisture on an ongoing basis, it’s definitely something to be concerned about.

Condensation Between the Panes

Most modern windows are double-glazed, with a seal separating the two panes. When moisture appears between the panes, it’s a sure sign that the seal has failed and your windows are no longer able to do their job properly. If you’ve been trying to clean your window without any luck, that’s a sure sign that you have moisture between the panes. And if that’s the case, your only options are to either completely replace the sealed units or consider replacing the windows.

The Effects of Condensation

You can clean excess moisture off your windows on a regular basis, but what you don’t see may be causing a lot of damage. No matter how often you wipe off the water, it can be rotting the windowsills, peeling the paint around the windows, and rotting the drywall, insulation, and window casing, and even the framework below and beside the windows. Worse, the constant presence of moisture creates the perfect situation for mold to develop. All these things happen without you even noticing them, but the damage to your home (and to your health, in the case of mold) can be severe.

How To Stop Condensation

There are a few things you can do to stop or reduce the amount of condensation on your windows:

Reduce humidity levels. Lower the settings on your humidifier, or turn it off completely, and try to reduce other causes of humidity, like cooking or long showers.
Improve ventilation and air circulation. Use bathroom and kitchen fans as much as possible. Open blinds and drapes, and remove any objects that might interfere with the airflow around your windows.

What Not To Do

You might consider using window films or caulking to prevent condensation. These may seem to stop the problem but they only make it worse by forcing the moisture into areas you can’t see, potentially causing major damage.

When Nothing Else Works

If you’re lucky, your problems were minor and the solutions above worked to eliminate the condensation. But if that’s not the case, your only option is replacing your windows. You’ll stop the condensation problem, and you’ll end up with a more comfortable and safer home while lowering your energy bills.