Skylights and Skylight Leaks
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Roof windows and why they leak: failed flashing kits, cracked seals, and condensation — plus why most leaking skylights are reflashed rather than replaced.
What Is Skylights and Skylight Leaks?
A skylight is a glazed unit set in a curb or deck-mounted frame, waterproofed by a manufacturer flashing kit that laces into the surrounding shingles. When one 'leaks,' there are three distinct failure modes to separate. Flashing failure — aged, improperly layered, or sealant-patched flashing — is the true roof leak, and it is the most common. Unit failure — a cracked dome, a failed insulated-glass seal that fogs between panes, or perished gasket seals — is a window problem on the roof. Condensation — interior moisture hitting cold glass, common over kitchens and baths — is a ventilation problem that drips convincingly without any breach. Because flashing failure is the usual cause, most leaking skylights are reflashed rather than replaced. Replacement is warranted when the unit itself is cracked or failing, and is decided on the skylight's condition and the agreed scope. During a reroof the flashing is redone with the new roof, which is also the time to check the unit's condition. Hail commonly cracks acrylic domes, making skylights routine line items on hail claims.
Important Distinction
Note: Not every wet skylight is a leak: condensation on cold glass and failed insulated-glass seals (fogging between panes) both mimic roof leaks and have different fixes.
Dealing with this on your own roof? Call (512) 893-7663 or get an instant online quote — Zilker Roofing inspects before recommending. Honest assessment.
Also Known As
These are the search terms and phrases that commonly refer to this topic, so you can find it however you describe it.
What this topic can lead to
A skylight leaks as a roof only when its flashing fails — aged, improperly layered, or sealant-patched flashing is the true roof leak — while a cracked dome or failed glass seal is a window problem on the roof and condensation on cold glass drips convincingly without any breach.
Topics related to this one
Most skylight leaks are flashing failures, not glass failures — which is exactly why VELUX conditions its 10-year installation warranty on its own flashing kit being installed.
Understanding which VELUX system is on the roof — deck- or curb-mounted, fixed or venting — is the first step in diagnosing why an existing skylight leaks or planning its replacement at reroof time.
Skylight repair begins with the three distinct failure modes to separate — flashing failure, unit failure, and condensation — because only flashing failure is the true roof leak, and the three have different fixes.
Questions about Skylights and Skylight Leaks?
Zilker Roofing inspects before recommending. Honest assessment.