Skylight Leak Repair or Replacement?
A skylight leak can start at the flashing, the roofing around the opening, the skylight frame, or the glass seal. Condensation can create similar stains even when rain is not entering from outside.
The right fix depends on the source and the age of the unit. A bead of caulking may hide the problem for a season, but it rarely replaces a proper diagnosis.
Confirm whether the moisture is rain or condensation
Track when the stain or drip appears. Water during wind driven rain points toward flashing, roofing, or an exterior seal. Moisture during cold weather without rain may come from indoor humidity condensing on the glass or frame.
Clues worth recording
Which direction the rain came from
Where the first drop appears
Whether moisture forms on the glass surface
Any fogging between panes
Staining around the shaft or ceiling opening
When a skylight can often be repaired
A sound, reasonably young skylight may only need corrected flashing, replacement roofing around the opening, or a focused exterior repair. The contractor should remove enough material to see the actual water path and rebuild it correctly.
Flashing matters most
Skylights interrupt the roof drainage plane. Head flashing, side flashing, sill flashing, underlayment, and shingles must direct water around the opening. Surface sealant cannot compensate for missing or badly layered flashing.
Learn how a complete Oakville skylight installation integrates the unit with the roof.
When replacement is the better choice
Replacement usually makes more sense when the insulated glass seal has failed, the frame is cracked or distorted, the unit has repeated leaks, replacement parts are unavailable, or the skylight is near the end of its useful service life.
Coordinate with roof replacement
If the roof will be replaced soon, compare the cost and risk of reinstalling an older skylight with installing a new matched unit and flashing kit. Replacing both at once gives the contractor full access to the deck and drainage layers.
Check the opening below the skylight
Water can damage the shaft, insulation, vapour control layers, drywall, and framing before it becomes visible. The inspection should include accessible interior areas, not only the glass and exterior frame.
Do not ignore fog between panes: Moisture trapped inside an insulated glass unit indicates a failed glass seal. Exterior caulking will not remove it.
Ask for a repair scope you can verify
The written estimate should name the suspected cause, the materials being removed, the flashing or unit being installed, interior work included, and the workmanship warranty.
If water has spread beyond the skylight, arrange a broader roof inspection. For active entry, review Oakville roof leak repair options.
Frequently asked questions
Can a leaking skylight be repaired without replacement?
Yes, when the unit is sound and the leak comes from flashing or nearby roofing. The repair must restore the complete drainage path.
Why does my skylight leak only in winter?
Condensation, snow melt, ice, or an exterior flashing issue can create winter moisture. The timing and location need inspection.
What does fog between skylight panes mean?
It usually means the insulated glass seal has failed and moisture has entered between the panes.
Should I replace a skylight during roof replacement?
It is often the best time, especially for an older unit, because the deck and flashing are fully accessible.
Will caulking stop a skylight leak?
It may temporarily slow a surface opening, but it will not correct failed glass, damaged roofing, or improperly layered flashing.
Stop the leak at its real source
Get the skylight, flashing, roof, and interior opening checked together. Call (905) 484-7785 or request a skylight leak assessment.