A leaking skylight is most often a flashing or seal problem around the unit rather than a failure of the glass itself. Repair can mean re-sealing, replacing the flashing or, if the unit is old or damaged, replacing the skylight.
First question: is it really a leak?
Not every drip near a skylight comes from the roof. Condensation forms when warm, moist indoor air hits the cold surface of the glass, and it can run down the frame and look a lot like a leak. The difference is timing:
| Clue | Likely a leak | Likely condensation |
|---|---|---|
| When it happens | During or shortly after rain | On cold mornings, even when it hasn’t rained |
| Where the moisture is | Around the frame, drywall edges or in the light shaft | On the glass or inner frame surface |
| After a dry spell | Stains are still there but not growing | Recurs with indoor humidity and temperature changes |
Where skylights leak
- Flashing. The most common cause. Metal or rubber flashing around the frame fails, lifts or is incorrectly layered with the roofing.
- Sealant. Caulk or glazing seals dry and crack with sun exposure.
- Cracked or crazed glazing. Often from age, impact or thermal stress.
- The curb. On curb-mounted units, the raised frame can leak at its corners or where it connects to the roof.
- Roofing around it. Damaged shingles or underlayment close to the skylight can allow water to travel in.
Repair or replace?
If the skylight itself is in good shape, repairing the flashing and resealing is usually the lower-cost approach and often the right one. Replacement makes sense when the unit is cracked, its seals have failed between panes (visible as fogging inside the glass), it is very old, or it has leaked repeatedly despite repairs. A roofer can explain the options, and you can ask for both approaches to be priced.
What happens during repair
- Assess from inside and outThe roofer checks the light well, ceiling, and roof around the skylight, looking for water paths.
- Remove surrounding roofingShingles around the skylight are lifted so the flashing and underlayment can be examined.
- Re-flash or replaceNew flashing pieces are layered correctly, or the skylight is lifted out and replaced with a matching unit.
- Reinstall roofing and sealShingles are restored and sealant applied where needed.
- Check the interiorWet insulation, drywall stains and mold risk are discussed. Interior repair is separate from roof repair.
A ceiling stain that has been painted over can hide an ongoing leak. If a stain reappears or you see bubbling or a soft spot, assume water is still getting in.
Skylights share many failure points with other roof penetrations. For a broader look at how flashing fails around chimneys, walls and valleys, see the roof flashing leak repair page, and for how an active leak is dealt with, see same-day roof leak repair. If you’d like to understand how the whole call-to-repair process works, check our overview of roof leak repair services in Walnut Creek. Condo and townhome owners with a skylight in a shared roof will find extra context on the Diablo Hills page.
Skylight leak questions
Why does my skylight leak only in heavy rain?
That usually points to a flashing or seal gap that only lets water through when it’s pushed or arrives in volume. Wind-driven rain makes it worse.
Can I re-caulk the skylight myself?
Ground-level or interior touch-ups are one thing, but working on the roof is dangerous and caulk alone seldom fixes flashing problems. A professional should handle it.
How long do skylights last?
It varies with the model, installation and exposure. Many are replaced because of failed seals or flashing before the unit itself wears out.
What about a skylight leak that has damaged my ceiling?
The roofer addresses the cause of the leak. Drywall, insulation and paint are interior repairs, usually handled separately.
Related services
Skylight dripping?
Call to be connected with an independent roofer who can tell whether it’s a leak, a seal or condensation.