A dripping skylight can come from condensation, glazing, the skylight unit, or the roofing and flashing around it. The visible drip is not reliable proof of the entry point, so a professional diagnosis should follow the water path rather than guessing from one stain.
Protect the interior first
- Move furnishings and catch active drips without climbing on the roof.
- Photograph stains, drips, and the weather conditions when they occur.
- If a ceiling is bulging, keep clear of it and contact a qualified professional promptly.
Condensation or an exterior leak?
Condensation often appears on the room-side glass during cold weather when indoor humidity meets a cold surface. A leak that follows rain, wind-driven rain, ice buildup, or roof debris needs an exterior inspection. Both can occur at once.
| What you observe | Possible explanation | Useful detail to record |
|---|---|---|
| Moisture on the room-side glass in cold weather | Indoor condensation may be contributing. | Indoor humidity, outdoor temperature, and whether moisture clears later. |
| Drips only during wind-driven rain | Flashing, roofing, glazing, or a nearby penetration may admit water under that exposure. | Wind direction, rain intensity, and the first place moisture appears. |
| Stain grows after snow or ice melts | Water may be entering around the skylight or elsewhere upslope. | Snow conditions, timing, attic observations, and photos. |
| Clouding or moisture between panes | The insulated glass seal may have failed. | Whether the moisture is between panes rather than on a cleanable surface. |
Common leak paths
Roofing professionals inspect the skylight curb, flashing sequence, underlayment, nearby shingles, fasteners, glazing, and drainage path. Caulk may temporarily cover a symptom, but it is not a dependable substitute for correctly integrated flashing and roofing materials.
Water can enter above the skylight and travel along underlayment, framing, or drywall before it becomes visible. That is why a stain at the lower corner does not prove the lower flashing failed. Leaves and debris can also interrupt drainage around the unit. The inspection should consider the skylight, surrounding roof, attic side when safely accessible, and the conditions that trigger the leak.
What a leak inspection should include
- Homeowner history: when the symptom started, which weather triggers it, prior repairs, and the approximate skylight and roof age.
- Interior review: stain pattern, glazing, frame, shaft, finish damage, and signs that moisture may be recurring.
- Exterior roof review: roofing condition, flashing components, curb or deck mount, penetrations, fasteners, and drainage paths.
- Documented options: the observed evidence, limits of the inspection, and whether a targeted repair or coordinated replacement makes more sense.
Repair or replace?
The decision depends on the skylight age and condition, compatible replacement parts, flashing condition, and whether the surrounding roof is nearing replacement. An inspection should explain what was observed, what remains uncertain, and the options before work begins.
Repair may be reasonable when
The skylight and glazing remain serviceable, compatible parts are available, the surrounding roof has useful life left, and the problem is isolated to a repairable roofing or flashing detail. The written scope should say whether materials around the unit must be removed and restored.
Replacement may be more practical when
The insulated glass or frame has failed, compatible parts are unavailable, repeated patches have not solved the problem, the unit is being removed during a roof replacement, or correction would require dismantling most of the existing assembly. Replacing a skylight during roof replacement can avoid disturbing a new roof later, but the condition and budget still control the decision.
Drying and follow-up
Stopping exterior water entry is only part of the job. Wet finishes and concealed materials may need drying or further evaluation. Avoid broad mold claims based on appearance alone; qualified remediation or indoor-environment professionals can advise when the affected area or occupant circumstances warrant specialized review. Keep photos and invoices, and monitor the repaired area during the weather conditions that previously triggered the leak.
Request a roof and skylight leak inspection if water appears after rain, stains spread, or the roof around the skylight is damaged. Related planning help: roof repair versus replacement and storm damage next steps.
Sources and safety review
- VELUX mounting and flashing systems—manufacturer explanation of integrated underlayment and flashing designed to shed water without relying on sealants.
- OSHA residential fall-protection guidance—roof access and fall hazards.
A visual check cannot guarantee the leak source; water can travel before it becomes visible indoors.
