What Does Condensation on Windows Mean for Me?

Is window condensation dangerous? Could a condensation build-up lead to necessary window repair or replacement?

We are probably all familiar with condensation on windows. Whether it’s droplets of water on our drinking glasses, car doors or house windows, condensation seems pretty unimportant. But, what exactly is it? Is window condensation dangerous? Could a condensation build-up lead to necessary window repair or replacement?

Condensation is more complicated than you thought. In this article, you’ll learn when to be concerned about condensation and what steps you need to take if necessary to protect your home.

What Is Condensation on Windows?

Tracking down the root cause of window condensation can sometimes be tricky, but in general, condensation on windows happens when warm, moist air collides with the cool surface of the window. Because glass is one of the coldest materials in your house, excess water vapor condenses there first, causing a fog effect and water droplets to form. 

Types of Condensation

If you live in an old house with old windows, make sure to take note of where on your window condensation appears. It can appear in one of three places: the outer side of the window, the inner side of the window or in between the panes.

For double or triple-pane windows, moisture between your glass panes is usually caused by a faulty seal. If you see this happening, it’s time to get concerned.

When Condensation Is Harmless

When there is condensation every now and then on the inside of your window, you can just grab a rag and wipe the window down. If this happens on rare occasions, you don’t need to worry, as moisture buildup isn’t a huge issue on its own.

But, if it is happening frequently and it is left untreated, it can lead to serious problems like mold, mildew and water damage. Frequent condensation means it’s time to get some help.

When Condensation Is Concerning 

When condensation appears between your glass panes, it usually means the seal is broken or damaged. If it’s not fixed, mold or mildew could begin to grow. The good news? It’s a fairly simple fix. You can correct the problem by replacing the insulated glass panel.

A hidden effect of condensation on windows, often not talked about, is rising humidity levels. When the sun comes up in the mornings, sunlight should just be heating our high performances home in the winter months. 

Instead, with condensation, the sun’s heat is being used up to evaporate the window condensation while also putting all that moisture back into the home’s exterior and raising the humidity level to uncomfortable levels. Our homes aren’t made to deal with moisture like that.

Even minor water damage can leave your home with severe stains and damage to your drywall. If it becomes affected by mold and mildew, you may find yourself with thousands of dollars in damages and have to replace your drywall, wallpaper, paint or even in severe cases, your furniture. And there’s also your health to consider, as there are many issues that can be caused by mold.

Steps to Take

Check for Ventilation Issues

Just like water won’t collect on an empty glass, condensation won’t be able to form on windows in a house that can’t hold humid hair. The solution? Make sure your house is ventilated! Confirm your dryer’s vent hose runs to the outside of your house. 

Next, check around your fireplace and inspect around your hearth for beading water. If your sealed fireplace goes unused, it can limit air circulation and create the perfect opportunity for mildew and mold to move on in. If you notice your home has a musty smell or discolored spots on the walls, your home may already have fungi running rampant. Make sure to get it checked by a professional.

You can enlist exhaust fans to ventilate excess moisture. Your bathroom and kitchen are high humidity spots and using an exhaust fan to send some of that excess moisture back outside can help dry out the air. Whenever you take a hot shower or decide to go crazy in the kitchen cooking, just flip the exhaust fan switch on.

Winterize Your Windows

Move any of your plants from the windowsill to further inside during the winter months because plants release moisture into the air as they grow. If you use a humidifier at home, consider turning it off in the winter or at least running it less frequently to protect your windows.

If the humidity in your home is causing issues, consider investing in a hygrometer to test your humidity levels.

And if your home is a few decades old, you can add weatherstripping around your windows to insulate your home. This accomplishes much of what newer, high-tech windows do at a fraction of the cost. 

Check If the Seal Is Broken

On older window units, the sealant used to create the window seal (around the windows) may age faster than the glass or frame of the window. If the seal and bead that is supposed to be holding the glass in the frame deteriorate, you will get moisture and water build-up in your frame. 

After a long amount of time, this will affect your ‘air gap’ seal surrounding your glass, and if your frame is made of wood, it will cause rot to occur. Check your seal, and if condensation is present between the panes, you are going to need to reseal or replace.

Hire a Reliable Window Repair or Replacement Contractor

If you get done winterizing your windows, checking your seals, and checking for ventilation problems and find yourself STILL having condensation problems, there’s no shame in hiring a professional. We at King County Windows & Glass are trained to look for other hidden sources of moisture, like rainwater seeping into your foundation or crawl space. 

Sometimes your best bet to prevent damage to your home (and avoid spending excess amounts of money) is to invest in a specialist, sooner rather than later. KC Window & Glass can provide you with the perfect solution to your condensation problems. 


When you’re dealing with broken glass, time is not on your side. That’s why we turn around quotes within 2 business days. All we need is a little information and a few rough measurements. What are you waiting for?