How to Clean & Remove Mold from Windowsills

Mildew and mold on windows aren’t just unsightly — they can damage your home and potentially impact the health of sensitive family members and pets. Learning how to effectively clean mold off windowsills, window panes, and window frames is key to maintaining a healthy environment.

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Why clean mold on windows?

Windows are exposed to moisture and temperature changes, which creates an ideal environment for mold and mildew. Common problem areas include window sills, frames, and even spaces between window panes. Mold on windows can also spread to nearby areas, making it essential to tackle it early.

What you need

Steps to clean remove mold and mildew from windowsills and frames

  1. Prep the area

    Remove any window treatments and nearby rugs. Place a towel under the window to protect the floor.

    Tip

    For better ventilation, open a nearby window or use a fan to help circulate fresh air.

  2. Pre-clean the surfaces

    If mold buildup is heavy, start by wiping the area with a wet microfiber cloth to reduce the amount of organic matter. Place the used cloth in the plastic bucket to wash later.

  3. Mix the bleach and water solution

    Wearing safety glasses and gloves, fill the spray bottle with 3 cups of water, then add 3 teaspoons of Clorox® Disinfecting Bleach. Insert the spray nozzle and adjust it to a fine mist.

    Tip

    Make bleach and water solutions fresh each day as they lose potency over time.

  4. Apply the solution to clean mold from windows

    Hold a cotton washcloth under the area to catch drips, then spray the bleach solution onto the moldy areas. Keep surfaces wet for up to 10 minutes, spraying as needed. Use a microfiber cloth to wipe away mold and an old toothbrush for crevices.

    Tip

    Use multiple cloths, switching out dirty ones as you work to avoid spreading mold spores.

  5. Rinse the window

    Dampen a clean microfiber cloth with fresh water and wipe all treated areas to remove any leftover bleach solution.

  6. Dry the window

    Use a clean, dry microfiber cloth to thoroughly dry the window and prevent moisture buildup.

  7. Wash the cleaning cloths

    After finishing, wash all used microfiber cloths and washcloths on a hot, heavy-duty cycle with laundry detergent and 1/3 cup of Clorox® Disinfecting Bleach.

Never mix bleach with ammonia, vinegar, or other cleaning agents, as this can produce hazardous gases.

Alternative cleaning methods for moldy windows

If you don’t have bleach on hand, you can try these DIY cleaning methods. Use caution, however – if the mold problem is serious, use a specialty disinfecting product or call a professional:

  • White vinegar solution: Spray undiluted white vinegar on moldy areas and let sit for an hour before scrubbing.

  • Hydrogen peroxide spray: Use a 3% hydrogen peroxide solution to kill mold on windowsills. Spray, let sit for 10 minutes, then scrub and rinse.

  • Baking soda paste: Mix baking soda with water to form a paste, apply it to moldy areas, scrub, and rinse.

Tips for success

  • Time: Allow at least 15–20 minutes for the entire cleaning process, including drying.

  • Skill level: Moderate; requires basic cleaning skills and attention to safety precautions.

  • Routine: Check windows for mold regularly, especially during humid months.

For more tips and products, visit our cleaning solutions category page.