Direct answer: A leaking skylight is usually caused by failed flashing, a bad seal where the skylight meets the roof, or water entering higher up and showing up at the skylight opening. Just as often, what looks like a leak is heavy condensation running down the glass or frame.
Most likely: Start by separating rain-related leaking from indoor condensation. If the water shows up only during or right after rain, suspect flashing or roof-path water first. If it shows up on cold mornings or after showers, suspect condensation before you touch the roof.
Skylights fool a lot of homeowners because the stain is obvious but the source often is not. Water can enter above the unit, ride the roof deck, and drip at the skylight opening. Reality check: the wet spot is not always the entry point. Common wrong move: sealing the visible crack line indoors and assuming the roof side is handled.
Don’t start with: Do not start by smearing caulk around the interior trim or the outside frame. That usually hides the path for a week or two and makes the real repair messier.
Water shows up during a storm or within a few hours after rain, often at one corner of the skylight trim or along the shaft drywall.
Start here: Treat this as a roof-entry problem first. Check the ceiling and attic side for a water trail above the skylight before sealing anything.
Moisture beads on the inside glass, then runs down onto the frame or trim, especially in the morning or after showers.
Start here: Treat this as condensation until proven otherwise. Improve ventilation and humidity control before assuming the roof is leaking.
The drywall around the skylight shaft is yellowed, bubbled, or soft, but active dripping is hard to catch.
Start here: Look above the stain path, not just at the worst spot. Old stains can spread from a roof leak that starts higher up the roof.
The skylight looks cloudy inside the glass unit and never fully clears, even when the room is dry.
Start here: That points to a failed skylight insulated glass seal, not a roof flashing leak. The unit or sash usually needs replacement service.
Rain-related leaking at the skylight curb or frame is most often tied to flashing that has lifted, corroded, loosened, or was never integrated well with the roofing.
Quick check: After rain, inspect the attic or ceiling cavity above the skylight for a water trail on the roof deck or framing near the uphill side of the skylight.
Water often enters from shingles, fasteners, or another roof detail uphill from the skylight and then runs down until it finds the skylight opening.
Quick check: Look for staining or damp roof sheathing above the skylight, not just around the skylight frame itself.
Bathrooms, kitchens, and tight homes can load the air with moisture. Cold skylight glass then sweats and drips enough to mimic a leak.
Quick check: If moisture forms on the room side of the glass during cold weather and not during rain, lower indoor humidity and improve exhaust use.
If moisture is trapped between panes or the frame gasket is visibly deteriorated, the skylight unit itself may be failing even if the roof is sound.
Quick check: Check whether the water is inside the glass assembly, at the sash edge, or only on surrounding drywall after rain.
This separates the two lookalike problems early and keeps you from chasing roof repairs when the issue is indoor moisture.
Next move: If the dripping stops when indoor humidity drops and there is no rain connection, you are dealing with condensation, not a roof leak. If water appears during storms or the drywall stays wet regardless of indoor humidity, move to roof-path checks.
What to conclude: Timing tells you more than the stain does. Condensation usually tracks weather and indoor moisture load, while true leaks track rain or melting snow.
Skylight openings are common collection points, but the actual entry point may be higher on the roof.
Next move: If you find a clear trail starting above the skylight, focus on the roof area uphill and nearby penetrations. If the only wet area starts right at the skylight curb or frame, flashing or skylight seals move higher on the list.
What to conclude: Water follows gravity, but not always straight down. The highest wet evidence usually points closer to the real entry point.
A lot of skylight leaks come from failed roof integration, not from the glass itself.
Next move: If you see roof damage or obvious gaps around the skylight perimeter, the leak source is likely outside at the roof-to-skylight connection. If the roof looks intact from what you can safely see, but rain still causes leaking, the flashing may be hidden under roofing and need closer roof-level inspection.
A careful hose test can separate a skylight-frame leak from a roof-above leak, but only if done slowly and safely.
Next move: If water shows up only when the uphill side or perimeter is wetted, flashing or roof integration is the likely repair path. If it appears only when the glass/frame area is wetted, the skylight unit seals may be failing. If you cannot reproduce the leak, the problem may depend on wind-driven rain, ice backup, or a roof entry point farther away than expected.
Once you know whether this is condensation, flashing, or a failing skylight unit, the next move gets much clearer.
A good result: If the leak stops after humidity control or after a targeted roof/skylight repair, dry the area fully and watch through the next storm or cold snap.
If not: If water keeps returning after a roof-side repair, widen the search uphill on the roof or in the attic because the skylight may only be where the water exits.
What to conclude: The durable fix matches the source: moisture control for condensation, roof repair for flashing leaks, and skylight service for failed glass or frame seals.
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That usually points to flashing trouble, wind-driven rain getting under roofing, or a roof leak uphill from the skylight. Hard rain exposes weak roof details that may not leak in a light shower.
Yes. In a humid room, cold skylight glass can collect enough moisture to run down the frame and drip onto trim or drywall. It is common in bathrooms, kitchens, and homes with high winter humidity.
Not until you know exactly where water is getting in. Blind caulking often traps water, hides the source, and delays the real repair. It helps only when you have confirmed a small exterior seal gap and the surrounding flashing is still sound.
Fogging or droplets trapped between glass panes are strong signs the skylight glass seal has failed. Repeated leaking right at the frame with no roof-path evidence can also point to a failing skylight unit or sash seal.
Call when the leak happens in rain, the roof is unsafe to access, the drywall is sagging, water is near wiring, or you suspect flashing or roof damage around the skylight. Those repairs are usually roof-side work, not interior patch work.