Skylights look like ordinary windows, but they sit on a slope, and the glazing is not built to carry your weight. Here is a safe, inside-first method, what to use on glass versus acrylic, and the point where the job belongs to a crew.
In This Article
Why a skylight is the riskiest window in the house
Two hazards meet at a skylight. The roof slopes, and shingles turn slick when they are wet, frosty or furred with moss. And the glazing, whether glass or a plastic dome, can break under body weight even when it looks solid. Dust, leaves and a skin of snow can hide the edge entirely.
The rule that follows is simple: never step, kneel or lean on a skylight, and stay off the roof unless you are trained and equipped for roof work. Ontario has Working at Heights training for workers. It is not a homeowner requirement, but it shows how seriously the trade treats a roof. Everything below works from a room, the ground or the eave.
Start inside, where the floor is flat
- Protect the space. Move furniture from under the opening and lay drop cloths. Water and grit will drip.
- Choose stable reach. Use a step ladder on level floor, or an extension pole with a microfibre pad if the ceiling is high. Keep your hips between the rails and never overreach.
- Dust before you wet. Lift loose grit with a dry, soft cloth or a vacuum brush, so nothing gritty gets dragged across the surface.
- Wipe with mild soapy water. Use a damp microfibre cloth, then wipe the frame and the light shaft walls.
- Dry and look. Buff with a clean cloth, then check the shaft for stains, peeling paint or damp patches. Photograph anything odd, with the date.
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The outside, without climbing onto the roof
Choose a mild, overcast day above freezing, with a dry roof. Direct sun heats the glazing and dries water before you can clear it.
- From the ground. If the skylight is visible and within reach of a pole, use a telescoping pole with a soft brush, or a hose, after pre-rinsing to float grit away.
- From a ladder at the eave. Only if you can reach the glass from the ladder without stepping onto the roof. Set the ladder on firm, level ground with a standoff, keep three points of contact, and stay well away from wires. The Electrical Safety Authority says to keep ladders and tools at least 3 metres (about 10 ft) from overhead powerlines.
- If you cannot reach it from either. Leave it. A dirty skylight is a small problem. A fall is not.
Glass or acrylic: match the cleaner to the glazing
| Glazing | What to use | What to avoid |
|---|---|---|
| Glass | Soapy water, microfibre and a squeegee, as for any window. | Razor blades on coated or tinted glass. |
| Acrylic or polycarbonate dome | Mild soap, plenty of water and a soft cloth. | Ammonia-based cleaners, solvents and abrasive pads, which can craze or scratch plastic. |
| Tubular skylight dome and diffuser | The same as an acrylic dome outside, and a soft damp cloth on the diffuser from inside. | Dry wiping grit off the dome. |
| Low-E or tinted glazing | Gentle wash, no abrasives. | Steel wool, scrapers and gritty cleaners. |
If you have the maker's care sheet, follow it over any general advice here.
Check the curb and flashing while you are looking
Cleaning is a good excuse to inspect. Fall leaves, needles and maple seed pods pile against the upslope edge of a skylight and hold water there. Moss on the shingles nearby suggests that moisture is lingering. From the ground or a ladder, look for these signs.
- Debris packed along the curb, or granules and moss on the surrounding shingles.
- Cracked, shrunken or missing sealant, or lifted flashing.
- Rust-coloured or brown stains on the shaft inside.
- Condensation between panes of a sealed glass unit, or a dome that has yellowed or crazed.
Any of those points to a roofer or skylight installer, not a window cleaner.
When the job needs someone on the roof
If the only way to the glass is over the shingles, hand it to a crew. D&D Home Services' crew members are Working at Heights certified and its window cleaning starts from $125 for typical Kitchener-Waterloo homes. Ask any company whether skylights are part of the quote and exactly how they will reach them. Read ladder safety for exterior home maintenance before you set up anything yourself, and see window cleaning for what a professional visit covers.
Key Takeaways
- Never step, kneel or lean on a skylight, and stay off the roof unless you are trained and equipped.
- Clean from inside first, then reach the outside from the ground or a ladder at the eave, keeping 3 metres from powerlines.
- Use plain soapy water and soft cloths on acrylic domes, and avoid ammonia, solvents and abrasives.
- Debris on the curb, cracked sealant or brown stains inside are jobs for a roofer or installer.
Sources & References
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