How to Remove Mold from Window Sill & Window Frame
What You'll Need
- Spray bottle
- 2 tbsp
- 1
- 2
- 1 pair
Step-by-Step Method
Wear rubber gloves. Open the window for ventilation.
Spray undiluted white vinegar on all moldy areas of the sill and frame. Let sit 10 minutes.
Make a paste of baking soda and water. Apply to moldy areas and scrub with a toothbrush. The baking soda provides gentle abrasion while vinegar handles the mold.
Wipe all surfaces with a clean damp cloth. Dry thoroughly with a dry cloth. Moisture left behind feeds regrowth.
Window sill mold is caused by condensation. Improve air circulation near windows, use a dehumidifier in winter, and wipe condensation from windows daily during cold months.
- Do not ignore window sill mold (condensation mold indicates humidity is too high in the room)
- Do not paint window sills without removing mold first
- In winter, wipe window condensation every morning. This 30-second habit prevents mold entirely.
- If condensation is severe, the indoor humidity is too high. Use a dehumidifier or improve ventilation.
- Keep curtains slightly open near windows to allow air circulation and prevent moisture trapping.
Frequently Asked Questions
Warm indoor air holds more moisture than cold outdoor air. When warm, humid indoor air contacts the cold window surface, the moisture condenses. This condensation sits on the sill and feeds mold. The fix: reduce indoor humidity (dehumidifier, ventilation) and wipe condensation daily.
Sources & Methodology
Window condensation occurs when indoor humidity exceeds the dew point at the window surface temperature. ASHRAE recommends indoor relative humidity of 30-50% to prevent condensation.
Last reviewed: March 20, 2026