How long does a skylight last?
Updated August 2026
A skylight lasts 10–20 years, and the glass seal usually surrenders first, at 10–15. Two separate things are aging up there. The insulated glass unit is sealed like a window, so a failed seal means permanent fog between the panes and a colder inner surface every winter. The flashing kit around the curb is the other half, and it is where nearly every skylight leak actually starts: not through the glass, but through a flashing detail that got shortcut at install or left unsealed at year 15. Manufacturers warrant the seal for 10 to 20 years and the flashing for about 10, which is an honest map of what fails when.
Lifespan by type and situation
| Type or situation | Typical lifespan | Why |
|---|---|---|
| Fixed (non-opening) unit | 15–20 years | Fewest moving parts, so it lasts longest; still bounded by the glass seal |
| Venting or motorized unit | 10–15 years | The hinge, gasket, and motor each add a failure point |
| Acrylic or plastic dome | 10–15 years | Yellows, crazes, and grows brittle under years of UV |
| Insulated glass seal | 10–15 years | The usual first failure, showing as fog trapped between the panes |
| Flashing kit and sealant | 10–20 years | The real leak source; replace it with the roof, never reuse it |
Signs yours is near the end
- Fog, haze, or droplets trapped between the panes that never clear up
- Water stains or bubbling paint on the ceiling around the light shaft
- Cracked, dried, or missing sealant at the flashing and along the curb
- A plastic dome that has yellowed, crazed, or split
- A venting unit that no longer seats tight, or a motor that stalls partway
How to add years
Skylights die of water, and the water gets in at the edges. Renewing the sealant around the flashing every 2 to 3 years is the single habit that pushes a unit past 20 years, and it costs a $12 tube of roof-grade sealant. Keep the shingles above and around it clear of leaves and pine needles, since debris dams water against the curb, and pull snow off a low-slope skylight before an ice dam forms uphill of it. Clean the glass once a year and look at the gasket while you are there. Do not caulk over a leak and hope: a skylight that drips for a season rots the shaft framing and ruins drywall and insulation, $2,000 to $6,000 of interior repair against a $300 flashing fix. Always install a fresh flashing kit when the roof is replaced. The repair-or-replace guide weighs a $200–600 glass swap against a new unit, and the routine sits on the skylight maintenance checklist.
What it costs to replace: plan on $1,000–2,500 installed. Replacing on your own schedule, before it fails, is almost always cheaper than the emergency version. The home maintenance cost calculator helps you set the money aside before it comes due.
OnOtto tracks your skylight seal checks age and service history, and warns you before end of life instead of after the flood.
Track your home's systems, free for 30 daysFrequently asked questions
Why is my skylight leaking?
Nine times in ten, the flashing rather than the glass. Water running down the roof hits the upslope side of the curb and needs step flashing plus a head flashing to route around it; any shortcut there leaks the first time rain comes in sideways. The other frequent source is condensation, which drips off the glass in a humid bathroom or kitchen and gets mistaken for a leak. Timing separates them: a flashing leak shows up during or right after rain, condensation shows up on cold mornings with no rain at all.
Should you replace a skylight when you replace the roof?
If the unit is more than about 10 years old, yes. The flashing has to come off and be replaced regardless, and installing a new skylight while the roof is already open costs a few hundred dollars in labor instead of $1,000 or more as a standalone job later. A skylight that outlives its flashing by a decade is the classic way a brand new roof develops its first leak. If the unit is under 5 years old, keep it and buy a fresh flashing kit sized to it.
Can a foggy skylight be fixed without replacing it?
Partly. If the frame and flashing are still sound, many manufacturers sell a replacement glass unit for the existing frame at $200 to $600 installed, which clears the fog and restores the insulating gas fill. Defogging services that drill and vent the pane cost less but never bring back the energy performance. Neither move pays on a 20-year-old assembly with tired flashing, since you would be spending on the one component that still works. The age of the whole unit drives the call.
Do skylights make a room too hot?
An older one will. Clear glass on a south or west roof face throws real heat into the room, and single-pane or acrylic domes are worse. Modern units with low-E coatings and argon fill cut solar gain substantially, and tinted or laminated glass cuts more. An interior blind, manual or motorized, runs $150 to $400 and gives you control on the worst afternoons. If a room already bakes, put the unit on a north-facing slope or size the glass to about 5% of the floor area.