Leaking Skylight: Repair or Replace?

Is it condensation or a real leak?

Condensation on skylight glass or framing can resemble a roof leak. Warm indoor air hitting a cold skylight can condense and run down the frame — especially in cold, humid weather and on units without a thermal break. Timing and location are useful clues, not a diagnosis: condensation often appears in cold conditions without recent rain and concentrates on the glass or frame, while a real water-entry leak usually tracks with rain or wind and shows up around the perimeter where the skylight meets the roof. Because those patterns can overlap, an inspection is what separates the two rather than the symptom alone.

What does an integrated skylight inspection check?

A skylight isn't a standalone part — it's integrated with the roof, so an inspection looks at the whole assembly rather than the unit alone.

• Flashing — step flashing, head flashing (uphill), and sill flashing (downhill), and whether they're properly lapped into the roofing.
• Surrounding roofing and cladding — shingles or membrane around the opening, and the siding or cladding above it.
• The unit itself — the frame, gaskets, glazing seals, and any visible cracks or failed seals.
• Decking and the rough opening — soft or water-damaged wood around the curb that needs repair.
• Curb and insulation — whether the curb is sealed and insulated and whether the unit matches the curb it sits on.

When can a skylight be repaired vs. replaced?

Repair makes sense when the unit is sound and compatible — the glass and frame are in good condition, the seals are intact, and the problem is the flashing or the roofing integration around it. Replacing or re-integrating the flashing, repairing the surrounding shingles, and fixing the curb can stop the leak without a new unit. Replacement is the better call when the unit itself is damaged — failed seals, a cracked frame, rotting wood, or a model that no longer matches the opening or the roofing system — or when the roof around it is being replaced and the skylight is the weak link. Coordinating a skylight assessment with a reroof is the right time to decide, because the flashing can't be done correctly without access to the unit.

Why isn't caulk a fix?

Sealant has a role, but it isn't a repair strategy. Applying sealant without identifying the entry path can hide the underlying problem; repairs should follow the unit manufacturer's instructions and proper flashing integration. A proper repair addresses the actual entry path — re-flashing, replacing damaged components, or replacing the unit — so the roof assembly sheds water the way it was designed to.