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How to Clean Moldy Window Sills and Frames

How to Clean Moldy Window Sills and Frames

Finding mold anywhere in your home is unsettling, to say the least. So, what do you do if your window sills and frames have mold? Review our detailed, two-step process to naturally and effectively remove mold and prevent it from re-growing below.

        • Protective Gear: Rubber Gloves, Mask, Goggles.
        • Disposable Cloths
        • Undiluted white vinegar or Hydrogen Peroxide
        • Baking Soda
        • Scrubber

Always dispose of the cloths in a zip lock bag or garbage bag and tie it securely.

Step-by-Step Guide to Removing Mold From Windows

Damp conditions such as humidity and condensation are the main reasons why mold forms on your window sills and frames. When moisture collects and is left unintended, it is a perfect environment for mold to form. Dirt also contributes to the growth of mold because it provides nutrients for the mold to feed from.

Step One: Removing Excess Mold

Before you start make sure you open the window for extra ventilation. Dampen the area by spraying it with water. The goal of this is to ensure the mold spores don’t spread while you are cleaning. Then wipe with a dry disposable cloth (we recommend microfiber, more on this below). The goal here is to not scrub and remove all the mold, but just get rid of what is easily wiped away.

Step Two: Deep Cleaning Mold with Bleach, Vinegar, or Hydrogen Peroxide

When researching the best ways to remove mold from windows, bleach was the most commonly mentioned. However, according to this article by Mold Help for You, you should never use bleach to kill mold because it only kills surface mold, thus will grow back. They recommend using vinegar instead.

Pour undiluted distilled white vinegar into a spray bottle and spray the affected area generously. Let the vinegar sit for about 60 minutes before wiping the area clean with warm water and a disposable cloth. Spray the affected areas one more time and let them air-dry to ensure you have fully killed the mold.

If you don't have vinegar, hydrogen peroxide is another great, natural alternative to bleach. Fill a spray bottle with at least a 3% concentrate of hydrogen peroxide. For non-porous surfaces like glass, mix it with equal parts hot water and spray the mold and let it sit for 15 minutes. Then rinse and wipe away with your cloth.


For harder to remove mold, use a baking soda solution with a scrubber to scrub it off. Baking soda works well because it is a natural abrasive. Combine one teaspoon baking soda with two cups of water. Pour it into a spray bottle, shake and spray it onto the mold. Scrub with a brush or scouring pad.

Then, wipe the area clean with warm water and a disposable cloth. Spray the affected areas one more time and let air-dry to ensure you have fully killed the mold.

How to Prevent Mold on Windows

Now that you know how to clean moldy windows, here’s how to prevent it from becoming a problem again, according to

“Keep mold away by removing condensation from your windows regularly. Wipe away any moisture that comes into your casings with a dry cloth. Whenever possible, keep your windows open so the wells are properly ventilated on days after rainfall. Continue to clean out the window wells at least once per 1-2 months to prevent any mold from developing.”

Microfiber and Mold Removal

When removing a potentially high risk substance like mold from windows and window sills, it’s extremely important to use tools that will do the best job. That’s why we recommend microfiber. Not only is it super absorbent, but more importantly, microfibers are smaller than mold spores, thus able to effectively pick them up! Here’s a size breakdown: A human hair has a diameter of 100 micrometers (microns), a microfiber is 1/100th the diameter of that (1 micron), and mold spores typically range from 3-40 microns.  

To prevent cross-contamination or accidental spread to other areas, you should be using disposable microfiber when tackling tasks with mold. Check out our Disposable Microfiber Cloths below.

Please note, if you have a mold issue that goes beyond isolated growth on windows, sills, shower or bathtub grout or caulking, we strongly urge your to contact an expert in mold remediation as patches on walls, flooring, woodwork, or other surfaces in your home may be indicators of a larger problem.

Our curated cleaning kit for homeowners

We’ve curated a cleaning kit of our favorite must-have products to keep a home in top shape. It contains two types of microfiber towels, a microfiber duster, and a heavy duty mop. Check it out!


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