Solution for Cleaning Window Mold

Mold is all around us, but a damp environment can create significant mold growth. Windows are designed to keep most moisture out of the house, but we see a different source of moisture in Minnesota and Wisconsin than rain and snow. Relative Humidity gradients from big changes in temperature can create moisture to form on the interior of the bottom edge of glass. If the moisture is left alone, it can become the perfect place for prolific mold growth.

Black Mold On Windows

It’s not difficult to remove black mold from window frames or glass, but you do need to wear personal protective equipment (PPE) to keep the mold and cleaning solution off your skin and out of your airways. Open the window as you work to provide fresh air and make sure you are running a fan in the home to circulate air throughout the home.

Process for Cleaning Moldy Windows

Dislaimer: Before cleaning any surface, test a small area to make sure the solution won’t cause permanent damage. If you have concerns about wood, vinyl, or aluminum products, consult the manufacturer before proceeding.

1. Put on protective gloves, safety glasses and a face mask.

2. Wipe the glass and any other affected areas on the windows with a dry cloth, we like to use Norwex antibacterial microfiber cloths.

3. Mix a few drops of dish detergent with some warm water. Use this mixture to clean mold off the surface of the window frame or glass with clean cloth. If the area has a heavy amount of mold, use paper towels and dispose of the soiled paper towels in a plastic bag. Seal the bag tightly when you finish and dispose of it in the trash. If the mold doesn’t wipe off the windows, use a plastic scraper to loosen and remove it.

4. Mix 1/4 to 1/2 cup bleach in a gallon of water. Scrub the window frame and glass with this mixture using a clean rag. Allow the bleach to sit on the casings for 15 minutes to disinfect and kill any mold spores that remain. Other products people have had success with include Simple Green and Concrobium.

5. Rinse the window frame and glass well with clean water. Dry thoroughly. If there isn’t a breeze through the window to dry things quickly, set up a fan to help speed the drying process. In the alternative, use a hair dryer to dry the window completely.

Things You Will Need

  • Gloves
  • Safety glasses
  • Face mask
  • Spray bottle
  • Dish detergent
  • Microfiber cloths
  • Paper towels
  • Plastic bag
  • Plastic scraper
  • Bleach
  • Fan or hair dryer


  • Take steps to prevent mold from reoccurring. Raise your blinds, run exhaust fans, make sure your windows are properly insulated and have access or moving air.
  • Reduce the humidity in your home including by utilizing a whole house humidity controller like April-aire, reduce the number of plants in the house.
  • Install exhaust fans in rooms with high humidity such as the kitchen and the bathroom.
  • If refinishing is required use a Kilz primer followed by a high quality interior paint like Pro Classic from Sherwin Williams.
  • To help determine if mold is due to humidity or air infiltration, utilize a humidistat or thermal leak detector.


  • Disinfect any reusable items from this project by immersing them in the bleach and water mixture when you finish.
  • Keep children and pets out of the room where you are cleaning up the moldy window casings as a precaution. Once the windows dry, they can re-enter the room.
  • Wash the clothing you wear for the project in hot water as soon as possible to keep from spreading any mold spores that settled on your clothes. Use bleach in the wash cycle, if possible.


At Great Plains Windows and Doors, We are All Andersen Windows, All the time. And we’re the only ones doing it this way in the Twin Cities. Come check out our amazing showroom in Oakdale for more information.

If you need some help navigating a window service question, the window replacement process or looking to replace your entry door in the Twin Cities, look no further than Great Plains Windows and Doors. Our residential window experts are here to help. Find out more at or call us today at 651-207-4571.