Window Condensation in Winter: Normal or a Problem?

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It's a cold North Texas morning. You pour your coffee, look out the window, and the window looks back at you, dripping. Your windows are sweating.

Is that normal? Should you worry? Is your house trying to tell you something? Let's figure it out.

Why Do Windows Sweat?

It's the same reason your glass of iced tea sweats on the porch in July. When warm, moist air touches a cold surface, the moisture in the air turns into water droplets. In winter, the inside of your window glass is usually the coldest surface in the room, so that's where it shows up.

Things that add moisture to your house:

• Cooking, especially boiling pasta for a crowd
• Long hot showers
• Laundry and drying clothes inside
• Lots of houseplants
• A lot of people in the house, like a holiday gathering
• Humidifiers running full blast
• Aquariums

Where Is the Condensation?

This is the important question. There are three places it can be, and they mean three different things.

1. On the inside of the glass (the room side). This is the most common. It's about humidity in your house meeting cold glass. A little on a cold morning is normal. A lot, every day, is worth paying attention to.

2. On the outside of the glass. This happens on cool, humid mornings, especially with newer energy-efficient windows. It's usually a sign the glass is insulating well, because the outside pane stays cool. It burns off as the day warms up. Nothing to worry about.

3. Between the panes. This is the one that isn't normal. It means the seal on a double-pane window has failed. You can't wipe it off. Read our guide to foggy windows and broken seals.

When Is Inside Condensation a Problem?

A little fog that clears up by mid-morning is fine. It becomes a problem when:

• Water runs down the glass and pools on the sill
• The sills or frames stay wet
• You see black spots, mildew or mold on the frame, sill or caulk
• Paint is peeling or wood is soft around the window
• Drywall below the window is stained

Water sitting around windows day after day can lead to rot and mold. That's not something you want to discover in spring.

How Do I Cut Down on Condensation?

The fixes are mostly about lowering humidity and moving air:

1. Run the bathroom exhaust fan during and after showers.
2. Use the kitchen vent hood when cooking, and make sure it vents outside.
3. Open the blinds and curtains during the day so warm room air reaches the glass.
4. Turn down the humidifier if you're running one.
5. Keep air moving. Ceiling fans on low can help.
6. Make sure the dryer vents outside.
7. Wipe the sills on really cold mornings.

Could the Windows Be the Problem?

Sometimes. Older single-pane windows and aluminum frames get much colder than modern insulated windows, so they sweat more. Drafty windows can make it worse. If you're fighting condensation every day and the windows are old, it may be time to talk about options. See signs you need new windows.

What If I Find Mold?

Small spots of mildew on a sill can be cleaned. If you see mold on drywall, soft wood or stains spreading below the window, it could mean water has been getting into the wall. That's a call to our team. CMDR Restoration (TDLR RCO #1801), our mitigation partner, handles mold and water, and G3 repairs the windows and walls.

What Does G3 Do?

We'll look at the windows, the frames and the walls around them and tell you whether you're dealing with humidity, a failed seal, a leak or just a cold morning. No high-pressure pitch. See our windows and exteriors page.

Frequently Asked Questions

Windows sweating more than you are? Call (945) 300-9018 or use the button below to get a window quote.

Keep learning: see our Windows & Exteriors page, read Window Leaks and Hidden Water Damage in North Texas.