Skylights · Maintenance

Skylight maintenance

Skylight maintenance is mostly inspection, and most of the useful inspection happens from inside your house. Twice a year, look at the ceiling and light shaft for stains, check the glass for fogging between panes, and look in the attic around the skylight opening for damp sheathing or matted insulation. Everything on the roof — clearing debris off the head flashing, checking sealant, checking the roof covering around the curb — should be done by a contractor with proper fall protection during a normal roof inspection.

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Debris is the underrated killer. Leaves and pine needles pile up on the uphill side of a skylight, hold water against the flashing, and shorten the life of everything they touch. If you have trees over the roof, that pile-up needs clearing more than once a year — and it's a reason to have the skylight looked at whenever the gutters are done.

Inside, keep the humidity down in rooms with skylights. Persistent condensation on the glass isn't just annoying; it drips onto the shaft, feeds mold in the drywall, and gets misdiagnosed as a leak. A working exhaust fan in a bathroom with a skylight does more for it than any product you can buy.

For operable units, exercise the mechanism a few times a year and keep the tracks and weep channels clear. Motors, chains and rain sensors on venting skylights are the parts most likely to need service long before the glazing does.

VELUX suggests having skylights professionally inspected around the 30-year mark and treats persistent between-pane condensation, cracks and staining as replacement signals. If yours are that old and you're planning any roof work, that's the moment to deal with them.

How to choose

Inspect from inside, twice a year: Ceiling, shaft corners, glass, and the attic side of the opening. Stains and damp insulation show up there first.
Bundle roof-side checks with other roof work: Ask whoever cleans your gutters or inspects your roof to photograph the skylight flashing while they're up there.
Keep the uphill side clear: Debris dammed above a skylight holds water against the flashing. Under trees, that's the number one maintenance item.
Fix the humidity, not the glass: Recurring condensation in a bath or kitchen skylight is a ventilation problem. Run the fan longer before you spend money on the skylight.
Log what you find: Date-stamped photos each year make it obvious when something is changing, and they help enormously if you ever file a claim.

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FAQ

Skylights maintenance — common questions

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How often should skylights be inspected?

Look from inside at least twice a year, and have the flashing checked whenever a contractor is on the roof for anything else. VELUX recommends a professional inspection around 30 years of age.

Can I clean the outside of my skylight?

Not from the roof, no. Clean the interior face yourself and leave exterior cleaning to whoever is already up there with fall protection.

Does resealing a skylight every few years help?

Not really, and it can hurt. Skylights are meant to be kept dry by flashing, not sealant. Routine caulking hides flashing problems instead of fixing them.

What's the single most useful maintenance habit?

Keeping debris from damming above the unit, and keeping indoor humidity in check. Those two prevent most of the problems that get blamed on the skylight.

Sources

Where these figures come from

VELUX — How Often Do Skylights Need to Be Replaced? · retrieved 2026-07-26