Why Window Condensation Happens

Are your new Marvin windows creating more condensation than your old windows? Here are some common questions you may have.

Why does condensation happen?

Steam or condensation occurs on your windows when invisible water vapor in the air condenses on the cool glass. Think of when your glass of iced tea ‘sweats’ on a warm summer day. Windows are the coolest surfaces in the home during the winter months, so when your heat is on, window glass is the most likely surface for condensation to form.

Is condensation bad for my new windows?

Not necessarily- Condensation is actually a sign that your windows are doing their job by preventing air exchange from inside to outside. You may see more condensation on your new windows, but that’s because your old windows were less energy efficient. Your old windows allowed warm air to pass around them to the cooler air outside. Your new windows are preventing air exchange, keeping humid air in your home.

Could anything else in my home be causing condensation?

Definitely. Some things on this list may even surprise you!

  • A new house or renovation- many materials (especially wood) are still releasing moisture
  • Unseasoned fire wood stored in the home
  • Indoor plants
  • A lot of people in the home- normal talking, breathing, and perspiration of four people can add about half a pint of water to the air each hour.
  • A lot of home cooking
  • A hot bath or shower can cause extra condensation in the bathroom, and eventually throughout the house (the more people, the more showers!)
  • Bathrooms and/or kitchens that are not vented to the exterior of the home

How can I fix condensation on my windows?

If condensation on your windows & doors is an issue because of any of the above reasons, you can start by controlling and maintaining proper humidity levels in your home. Run a dehumidifier if it’s too high. Increasing ventilation in your home is also a way to manage condensation. Keeping kitchen and bathroom fans running a little longer, or simply cracking a window while cooking or bathing is a great start.

Okay, but when is condensation on my windows a problem?

Condensation on your windows or doors may be a problem, and is worth reaching out to your Windows & Doors By Brownell or Marvin sales representative, if one or more of the following applies:

  • Condensation occurs only on one window in the home (and not because of any of the above reasons)
  • Condensation stays on the window throughout the entire day, even after it warms up outside
  • Condensation forms between the panes of glass- this may indicate a seal failure
  • Condensation forms on walls
  • The air smells musty
  • Mold or mildew is visible on walls, ceilings and windows

Understanding where moisture comes from is the best way to help prevent condensation from forming in the first place.