Removing Mold from Your Windows


Winter brings many joys … the holidays, time with family and friends, fresh baked cookies, snow and roaring fireplaces.  Unfortunately, winter also brings some things that are not so wonderful including a brand new crop of indoor mold growth which can be found in any corner of your house.  Keeping mold at bay takes vigilance but one place where it is fairly easy to eradicate is on the surfaces of your windows.

Mold growth on the surface of your windows is an aesthetically unpleasant reality of winter.  Ugly black spots form on your windows because the warm indoor air and the cold outdoor air meet there and form condensation which, when it is unable to evaporate quickly, invites mold to take root and grow there.  It is important to note that mold does not actually grow on the inorganic surface of your window; mold grows on the organic material that settles on your window – dust, animal dander, dead skin cells and other flotsam of our human life creates a hospitable bed for mold to grow in.  Just add condensation and still air and voila!  You’ve got mold.

What to Do About Removing Mold from Your Windows?

Window Mold

Mold that grows on your windows is rarely of the most toxic “black mold” variety – constant temperature changes and poor quality of the food source make sure of that.  But that doesn’t mean you shouldn’t be careful when removing mold from your windows.  Non-porous gloves and a simple face mask to protect you from proliferating mold spores are still recommended.


. Wash windows with detergent, hot water and a brush or scratchy sponge.  Don’t bother with the chlorine bleach.  It’s bad for you and the environment and is like bringing a bazooka to do a popgun’s job.

. Rinse, then sterilize with water and white vinegar or rubbing alcohol.  This step will only prevent regrowth until there is a build-up of new food sources (again, dust, animal dander, dead skin cells, pollen, etc.) so make sure to clean your windows and window sills often with a damp rag rather than a feather duster (which simply redistributes the nasty stuff).

. Take steps to manage the inevitable regrowth of mold in the exact same spot.


Moldy Window

Simple Ways to Keep Mold Away

Unfortunately, unless you live someplace where the humidity is always around 50% both indoors and outdoors, mold will happen in your house.  Another unfortunate reality is that mold on and around your windows can happen in a brand new, energy efficient house (sealed too tightly) or an old, drafty, energy inefficient house (too leaky).  So, since there is no perfect house, what can you do?

. Any mold is a sign of too much moisture.  Invest in a dehumidifier and use it to keep the humidity between 40% and 60%.

. Allow some airflow.  Open some doors or windows, or run a ceiling fan or a tabletop fan.

. If it’s practical, add some insulation around your windows.

. Dry condensation off your windows with a clean rag.  This will remove both the water that mold needs and the food source that it loves … plus, your windows will be clean!

. Invest in a vacuum with a HEPA filter which will remove the microscopic “future food source” particles instead of launching them into the air to settle somewhere else.

. Clean all window sills and windows in the spring.  If mold is allowed to sit on your window surfaces through summer, they will dry and be harder to clean.

. Check the caulking around your windows and window sills to make sure moisture from your window surface is not getting into the walls where it will take much longer to dry.

. Finally, always check to see if your window mold is a sign of something bigger and more sinister happening in your walls or elsewhere.  Mold on your windows may simply be an ugly side effect of a larger – but hidden – moisture problem.


Mold On The Window

While it’s a normal part of winter to find mold growing on your windows, it’s ugly and should be removed as soon as practicable.  It’s easy to do so … and even easier to invest in a few preventative techniques like maintenance, proper care and appropriate cleaning to avoid a major mold problem that won’t be so easy to handle.

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