How to Clean Window Sills and Tracks

Window sills are a perfect horizontal surface for dust to settle. Since anything near a window is highly visible, a dirty window sill catches your eye every time you glance outside. Window tracks are even harder to reach, so dust, bugs, and debris build up there. Unlike dirty sills, dirty tracks cause functional problems: they can make windows hard to open and close, which can strain the window hardware or trim.

Here’s how to clean window sills and tracks inside and out, including how to handle mildew and how to care for different sill materials.

What You’ll Need

• A vacuum with a crevice tool or brush attachment
• Microfiber cloths
• An all-purpose cleaner, or warm water with a few drops of dish soap
• An old toothbrush or small detail brush
• Cotton swabs or a butter knife wrapped in a cloth for corners
• Optional: white vinegar, baking soda, and hydrogen peroxide for tougher grime and mildew

How to Clean Interior Window Sills

Cleaning interior sills is simple and gives immediate results. You don’t have to bend over like you do for baseboards or floors.

1. Dust or vacuum first. Remove loose dust, dead bugs, and debris with a vacuum brush or a dry microfiber cloth. Wiping a dusty sill with a wet cloth just makes mud.
2. Spray and wipe. Lightly spray an all-purpose cleaner (or soapy water) and wipe with a microfiber cloth. Work from one end to the other.
3. Detail the corners. Use a toothbrush or cotton swab for the corners and the joint where the sill meets the window frame.
4. Dry it. Wipe with a dry cloth so water doesn’t sit on the surface, especially on wood.

For a quick weekly touch-up, a dry or barely damp microfiber cloth is usually all you need.

How to Clean Exterior Window Sills

Outside sills collect pollen, dirt, bird droppings, and spider webs. Start by brushing off loose debris with a soft broom or brush. Then wash with a bucket of warm, soapy water and a sponge or soft brush, and rinse with a hose on a gentle setting or a bucket of clean water. Avoid pressure washers near windows; the force can push water past seals and damage paint, caulk, or wood. For second-story sills, only clean what you can reach safely from inside or from stable footing.

How to Clean Window Tracks

Some window tracks get so gummed up that nobody bothers to open the window anymore. Follow these steps to get them gliding again:

1. Vacuum. Open the window and use the crevice tool to pull out loose dirt, bugs, and debris.
2. Loosen the grime. Sprinkle a little baking soda in the track, then lightly spray it with a mix of equal parts white vinegar and water. Let it fizz and sit for about 10 minutes.
3. Scrub. Use a toothbrush to scrub the track and corners.
4. Wipe out the residue. Wrap a cloth around a butter knife or flat tool and run it through the track to pull out dirt. Repeat with a clean damp cloth.
5. Dry and check the weep holes. Dry the track and make sure the small drainage holes along the outside of the track are clear so rainwater can drain.

Skip the vinegar step on aluminum tracks with a damaged finish or on stone; soapy water works fine there.

How to Remove Mold and Mildew From Window Sills

Black or gray spots on sills and in tracks usually come from condensation, which is common on cold winter mornings. For small surface spots:

• Wear gloves and open the window for ventilation.
• Spray undiluted white vinegar or 3% hydrogen peroxide on the spots, let it sit for 10 to 15 minutes, then scrub with a brush and wipe clean.
• Dry the area completely.

If you prefer a diluted bleach solution on vinyl or painted surfaces, follow the product label, ventilate well, and never mix bleach with vinegar or ammonia; the combination releases toxic gases. Avoid bleach on unfinished or stained wood. To prevent mildew from returning, wipe away condensation, run bathroom and kitchen fans, and keep indoor humidity moderate. If mold covers a large area, keeps coming back, or the wood is soft, the problem may be a leak or rot that needs a professional.

Cleaning Window Sills by Material

Wood Window Sills

Painted wood sills handle mild soapy water well. Use a damp, not wet, cloth and dry right away, since standing water can lift paint and swell wood. For stained or varnished wood, use a cleaner made for wood and avoid harsh scrubbing. Many older homes have original wood sills with layers of old paint; homes built before 1978 may have lead paint, so avoid sanding or aggressive scraping of chipped paint.

Vinyl Window Sills

Vinyl is the easiest to clean. All-purpose cleaner, soapy water, or a 50/50 mix of water and vinegar all work. For scuffs, a paste of baking soda and water on a soft cloth helps. Avoid abrasive pads and solvents, which can dull or scratch vinyl.

Stone, Marble, and Granite Sills

Skip vinegar and other acidic cleaners on natural stone, since acid can etch the surface. Use a pH-neutral stone cleaner or mild dish soap and water, then dry with a soft cloth.

Finish With the Glass

Once the sills and tracks are clean, the glass is the natural next step. Our guide to cleaning glass windows walks through a streak-free method.

How Often to Clean Window Sills

Dust interior sills weekly or every other week, and give sills and tracks a deeper clean each season, especially in spring when pollen is heavy and in fall before windows stay closed for winter.

Let Us Handle the Details

Window sills are just one of the details on our written checklist. If you’d rather spend your weekend elsewhere, our bonded and insured housekeepers can take care of sills, baseboards, and more with a one-time deep cleaning. Request a free written estimate anytime.