Why Do I Have Moldy Basement Windows?

Why Do I Have Moldy Basement Windows?

Are your basement windows moldy? You might be wondering why. Moldy basement windows can be caused by a number of sources. It’s our job, as your local waterproofing company, to help you find out what it is and put a stop to it.

Leaky Windows

One of the most common causes of moldy basement windows is the windows leaking. If the windows in your basement are old and seem of dubious quality, they’re probably leaking. To find out if this is the problem plaguing your basement, follow these steps:

  1. Clean the window thoroughly. Remove any mold with chemical cleaners.
  2. Dry the window thoroughly. Make sure all moisture from cleaning is completely wiped away.
  3. Wait for it to rain
  4. Check the windows for moisture. You should check after it’s been raining for a few hours at least. If it’s dark, bring a flashlight and shine it on the window along where it meets the window frame. Also, shine it along where the frame meets the sill. If you don’t see any visible leaks, touch the frame to see if it feels slightly moist with condensation.

If your windows are leaky, you’ve found the cause of your moldy basement windows. The windows will need to be replaced entirely. If the leaking is around where the window is installed against the wall, check for water damage during the installation of new windows.

Window Well Flooding

If your basement windows are located at the bottom of window wells, there’s a good chance they’re moldy from window well flooding. Window wells that don’t have any kind of drain system are just a collection point for water. Whenever it rains, the water will gather at the bottom of the wells and sit against the basement windows. 

While windows should, generally, be waterproof, most aren’t meant to withstand pooled water sitting against them. They will leak, even if they’re decent windows. So, if your window wells are flooding when it rains, invest in window well waterproofing before worrying about the windows themselves. If there’s still a mold issue after window well waterproofing and thorough removal of the previous mold, you may want to revisit item #1.

Interior Condensation

Sometimes the source for mold is actually coming from inside. Interior condensation is incredibly common and leads to moldy basement windows all the time. Different temperatures on either side of a barrier pull water from the air on the warm side. This is why a glass of ice water collects moisture on its surface. The moisture from the warm air touches it and goes from gas form to liquid form.

If you keep your interior nice and warm and the air has any level of humidity in it, cold temperatures outdoors can pull moisture to the cold windows. The condensation then drips down to collect in the window frame or sill, leading to mold issues.

To solve interior condensation issues, you can opt to replace your windows with some that are better insulated, or buy a dehumidifier. A dehumidifier will pull the moisture from the basement’s air and prevent it from settling on the windows.

If these options are too pricy for you, the only solution left is to regularly take a trip down to the basement to dry and clean the windows, frame, and sill.