How to Clean Window Sills

Window sills collect dust, pollen, dead insects, water stains, and mold faster than almost any other surface in the home. Regular cleaning keeps them looking fresh and prevents moisture damage. Here's how to clean them properly.

Why Window Sills Get So Dirty

Window sills sit at the junction of inside and outside air. They collect dust blown in from outside, condensation from the glass, pollen in spring, and debris from the window tracks. In humid climates, mold and mildew are common on painted sills.

What You'll Need

• Microfiber cloth or soft sponge
• All-purpose cleaner or dish soap and water
• White vinegar (for mold and mineral deposits)
• Old toothbrush (for corners and crevices)
• Dry cloth for finishing

• Window Squeegee Cleaner with Extension Pole and Microfiber Scrubber — the microfiber scrubber pad works perfectly for wiping down window sills and frames

Step 1: Remove Loose Debris

Use a dry cloth, brush, or vacuum to remove all loose dust, dead insects, and debris from the sill. Do this before adding any liquid — wet dust turns into mud and is harder to clean.

Step 2: Apply Cleaning Solution

For general cleaning, spray with an all-purpose cleaner or a solution of dish soap and warm water. For mineral deposits or water stains, use undiluted white vinegar. For mold, use a solution of 1 part bleach to 10 parts water.

Step 3: Scrub the Sill

Wipe the sill with a damp microfiber cloth or sponge. For stubborn stains, let the cleaning solution sit for 2 to 3 minutes before scrubbing. Use an old toothbrush to get into corners and the joint between the sill and the window frame.

Step 4: Remove Mold (If Present)

Apply the bleach solution to moldy areas and let sit for 5 minutes. Scrub with a toothbrush and wipe clean. Rinse with a damp cloth. Ensure the area dries completely — mold returns if moisture remains.

Step 5: Rinse and Dry

Wipe the sill with a clean damp cloth to remove all cleaning solution residue. Dry thoroughly with a clean dry cloth. Leaving moisture on painted sills causes paint to peel and mold to return.

Step 6: Inspect the Paint and Caulk

While the sill is clean and dry, inspect the paint for peeling or chipping and the caulk joint for cracks. Touch up paint and recaulk any gaps to prevent future moisture damage.

• GE Advanced Silicone Caulk Window & Door Clear — recaulk any cracked joints on the sill to prevent water infiltration

Cleaning Different Sill Materials

• Painted wood: Dish soap and water; avoid abrasives that scratch paint
• Vinyl: All-purpose cleaner; magic eraser for scuffs
• Marble or stone: pH-neutral cleaner only; never use vinegar or bleach
• Aluminum: Dish soap and water; dry thoroughly to prevent oxidation

How Often to Clean Window Sills

• Dust weekly with a dry cloth
• Wipe down monthly with a damp cloth
• Deep clean quarterly or when visibly dirty
• Inspect for mold and paint damage twice a year