How to Clean Skylights, Inside and Out

Skylights get dirty on both sides and are awkward to reach from either one. The inside usually sits over a stairwell or a vaulted ceiling. The outside is up on the roof collecting dust, pollen, pine needles and whatever the last storm blew in. And because skylights here take a lot of direct sun, a dirty one is hard to miss.

Before you start, work out what kind you have, because it changes how you clean it.

Glass or plastic?

Flat skylights on most newer homes are glass, usually double paned. Bubble or dome skylights, more common on older homes, are usually acrylic or polycarbonate. Glass feels cold and hard and sounds solid when you tap it. Plastic sounds hollower.

It matters because plastic scratches easily. On an acrylic or polycarbonate dome, skip paper towels, abrasive pads, razor blades and ammonia-based glass cleaners, which can scratch or cloud the surface. Mild soapy water, a soft microfiber cloth and a rinse are all it needs.

Cleaning the inside

1. Put a drop cloth over the floor or stairs underneath.
2. Use an extension pole with a microfiber pad instead of climbing. Hardware stores sell poles that reach well past 12 feet.
3. Dust the frame and the shaft between the ceiling and the skylight first. Dead bugs and cobwebs collect there.
4. Wipe the glass with a pad barely damp with mild soapy water. Damp, not dripping, since anything extra runs back down the pole at you.
5. Go over it again with a dry pad.

If you do need a ladder, it has to stand level. A ladder on a staircase needs a proper leveler or a stair platform, and propping one leg on books or boxes is how people get hurt.

Check for one thing before you spend an hour up there. If the haze or condensation is between the panes rather than on the surface, the seal on the double-paned unit has failed and moisture has got inside. No amount of cleaning reaches it, and the glass unit needs repair or replacement.

Cleaning the outside

This part is roof work. Don’t go up if the roof is wet, frosty, steep, or covered in needles. Pine needles on shingles are slicker than most people expect, and a lot of foothills roofs sit under exactly that kind of cover.

If the roof is safe to walk on:

1. Clear the debris around the skylight by hand, especially on the uphill side, where needles pile against the curb and hold water.
2. Rinse the skylight with a hose on a gentle setting.
3. Wash it with soapy water and a soft brush or microfiber. Glass can take a squeegee. Plastic domes get a soft cloth only.
4. Rinse again and dry glass with a squeegee, because water drying in strong sun leaves hard water spots.
5. Look over the flashing and seals while you’re there. Cracked caulk or lifted flashing is how skylights start to leak.

Leave the pressure washer on the ground, since it can force water past the seals and flashing.

Snow and ice

Let snow melt off on its own. Shoveling or scraping snow off a skylight can crack a plastic dome and scratch glass, and chipping at ice around the edges can damage the flashing.

How often

Once or twice a year suits most homes, which lines up with a regular window cleaning. A skylight under pines, or on a low-pitched roof where debris sits instead of sliding off, needs attention more often than one under open sky.

Having them done

We clean skylights along with windows, and foothills homes with skylights over the great room or the stairs are a normal part of the job. Send the quote form and tell us how many skylights you have and roughly how high they are. Ceiling fans, light fixtures and chandeliers can go on the same visit, and the services page covers what else we do from the ladder.