The short answer
Safety First
Mold can irritate your eyes, skin, and lungs, so take precautions before you start. Put on rubber gloves, safety goggles, and an N95 mask to limit your exposure. Open windows or use a fan to keep the area ventilated while you work.
If you feel unwell during cleaning, stop and step outside for fresh air. See a doctor if symptoms persist. For large mold patches or mold in wall cavities, consider hiring a mold professional to handle the job safely.
Gather Supplies
You will need a few basic items: a spray bottle, mild dish soap, water, a soft sponge or cloth, a bucket, and a dry towel. Avoid mixing bleach with other cleaners, as this can create toxic fumes. For porous frames, a small brush can help scrub mold out of crevices.
For stubborn mold, a solution of one part bleach to ten parts water is effective on non-porous surfaces like glass. Never use bleach on wood without testing a small area first, as it can discolor the finish.
- Rubber gloves and safety goggles
- N95 mask or respirator
- Mild dish soap and water
- Soft sponge and dry cloth
- Spray bottle and bucket
- Small brush for crevices
Clean the Window
Start by spraying the window with your soapy water solution. Let it sit for a few minutes to loosen the mold, then scrub gently with the sponge. Work from the top down so dirty water does not drip onto clean areas.
Rinse the glass and frame with clean water using a separate cloth. Dry everything with a dry towel. Pay extra attention to the corners and the track where moisture often collects. If mold remains, repeat the process with the bleach solution.
Dry Thoroughly
Moisture is the main cause of mold, so drying is just as important as cleaning. Wipe down all surfaces, including the sill and frame, with a dry cloth. Leave the window open for an hour or two to let the area air out completely.
If your window has a condensation problem, use a dehumidifier or run a fan to reduce humidity. In a semi-arid climate with cold snowy winters and hot dry summers, indoor humidity can still spike from cooking and showers. Keep the area ventilated.
Prevent Regrowth
Mold will return if the moisture source is not fixed. Check for leaks around the window frame and seal any gaps with caulk. Wipe condensation off the glass regularly, especially during cold months. Use an exhaust fan in kitchens and bathrooms to lower humidity.
If mold keeps coming back despite your efforts, the window or the surrounding wall may be water-damaged. In that case, a water damage inspection can identify hidden moisture. If the window itself is old or damaged, window replacement may be a better long-term solution.
- Fix any leaks or gaps in the frame
- Wipe condensation daily
- Use exhaust fans in high-moisture rooms
- Keep indoor humidity below 50 percent
- Inspect for water damage regularly
- Consider replacing old windows
Water damage does not wait
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Call Now (801) 876-1119Frequently asked questions
Is bleach necessary to kill mold on windows?
Bleach is effective on non-porous surfaces like glass, but soap and water can remove surface mold. For porous frames, a mixture of vinegar and water may work better. Always test any cleaner on a small area first.
What should I do if mold is inside the window frame?
If mold is inside the frame, the frame may be water-damaged. Remove any loose material and clean as well as you can. If the frame is rotted or soft, you may need to replace the window. A water damage inspection can confirm the extent.
Why does mold keep coming back on my windows?
Mold returns when moisture and organic material are still present. Condensation from high indoor humidity is a common cause. Fix leaks, improve ventilation, and wipe condensation regularly. If the problem persists, consider a dehumidifier or window replacement.