Skylight Leaking? Causes, Fixes and When to Replace It

Short answer: most skylight leaks come from the flashing and seals around the skylight, not from the glass. If water only appears on cold winter mornings, it may be condensation, not a leak. If your skylight is 15 to 20 years old, foggy between the panes, or keeps leaking after patches, replacing it with a new flashing kit is usually the fix that lasts. According to Angi, a skylight replacement costs about $1,500 on average, and more for larger, vented or hard-to-reach units.

Is it a leak or condensation? How to tell

Before anyone climbs on the roof, figure out when the water shows up. That one detail usually points to the cause.

When you see water	Most likely cause	What to do
During or right after rain	Failed flashing, cracked seal, or damaged shingles around the skylight	Roof inspection and repair or replacement
Cold winter mornings, drops on the inside of the glass, no rain	Condensation from indoor humidity	Run bath and kitchen fans, lower humidity; older single-pane units may need replacing
After snow, at the bottom edge of the skylight	Snow melting above the skylight and refreezing below it (a small ice dam)	Check flashing, insulation around the shaft, and ice barrier
Fog or moisture between the glass panes	The glass seal has failed	Replace the unit; the seal can’t be repaired
Stains on the drywall around the shaft, no visible drips	Slow leak or condensation inside the light well	Inspect both the roof side and the attic side

What causes skylights to leak?

Worn or badly installed flashing

The metal flashing around a skylight is what keeps water out. It fails when it’s old, when it was installed without the manufacturer’s flashing kit, or when it was “fixed” with roofing tar. Tar dries out and cracks after a few seasons of sun and freezing weather, and then the leak comes back.

Aging seals and cracked domes

Seals between the glass and the frame break down over time. Older plastic “bubble” skylights also turn brittle, yellow and crack. Angi puts the typical skylight lifespan at about 15 to 20 years.

Damaged shingles around the skylight

Shingles right next to a skylight take extra water and debris. When they curl, crack or lift, water gets under the flashing.

Leaves, debris and snow

Debris piles up on the uphill side of a skylight and holds water against it. In winter, heat escaping through the skylight melts snow that refreezes just below it. UMass Amherst notes that ice dams often form below skylights for exactly this reason. More on that in our ice dam guide.

Can a leaking skylight be repaired?

Sometimes. A repair makes sense when:

• The skylight itself is in good shape and less than about 15 years old.
• The glass is clear, not fogged between the panes.
• The leak comes from one clear spot, like a lifted shingle or a loose piece of flashing.

Replacement is the better call when:

• The unit is 15 to 20+ years old, fogged, cracked or yellowed.
• It has been patched before and is leaking again.
• You’re replacing the roof now or in the next few years.
• You want better glass that keeps out heat in summer and holds it in winter.

Replacing your roof? Replace the skylight at the same time

A skylight’s flashing kit is designed for one installation. If an old skylight stays in place under a brand-new roof, the new shingles have to be worked around old flashing, and that spot becomes the weakest point on the roof. It also means paying to open that area again when the skylight fails a few years later.

Doing both together costs less than two separate jobs, gives you a new skylight warranty, and lets the crew wrap the opening with fresh underlayment and ice barrier. See what a roof replacement costs in NJ.

How much does skylight repair or replacement cost?

Angi reports an average of about $1,500 to replace a skylight and $1,000 to $3,000 to install a new one. Your price depends on:

• Size and type: fixed skylights cost less than vented or electric ones.
• Roof pitch and height: steep or second-story roofs take more time and safety equipment.
• Curb or deck-mounted: some older curb-mounted skylights need the curb rebuilt.
• Hidden damage: wet decking, insulation or framing around the opening.
• Inside repairs: stained or soft drywall in the shaft is a separate fix.

Resealing or re-flashing a skylight that’s otherwise sound costs less than replacement. The inspection will tell you which one you need.

What to do right now if your skylight is leaking

1. Put a bucket and towels under the drip, and move furniture and electronics away.
2. Take photos of the water and any stains, with the date.
3. If there’s a bulge in the ceiling, keep people away from it; it can be holding water.
4. Don’t go up on a wet roof. From the ground or a window, look for missing shingles or debris near the skylight.
5. Call a roofer. If water is coming in fast, we offer 24/7 emergency roof repair.

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Sources: Angi, “What Are Skylights?” (cost and lifespan); UMass Amherst Building and Construction Technology, “Preventing Ice Dams.”