What should you do when a skylight leaks?
Short answer. Catch the water, protect the floor and drywall, and note whether the drip happens during rain or on cool, dry mornings, because that separates a leak from condensation. If it is rain, clear debris from the uphill side, tarp over the skylight if needed, and have the flashing and glass seal inspected; most skylight leaks come from the flashing, not the glass.
Right away
- Put a towel or bucket under the drip and move furniture.
- Wipe the glass and frame dry, then watch where new drops form: on the glass surface (condensation or a glass seal), at the frame corners (flashing), or on the shaft walls (flashing or a roof leak above).
- If a heavy leak continues in a storm, a tarp over the skylight, secured well beyond it once it is safe to go up, will stop it.
- Take dated photos inside and out.
Why skylights leak
- Flashing installed without step pieces, or caulked instead of woven into the shingles.
- Debris dams of leaves and pine straw on the uphill side.
- Failed seals or gaskets on older units.
- Domes cracked by hail or age.
- Humid indoor air condensing on cold glass.
- A roof leak higher up, running down to the skylight.
Then fix it properly
Flashing leaks are fixed by pulling back the shingles and installing a new flashing kit with membrane around the frame. Fogged or cracked units are replaced, ideally at the same time as the roof if the roof is older. Smearing caulk around the frame usually makes the next repair harder.
If it is condensation
Run the bath or kitchen fan, lower indoor humidity, and crack a venting skylight on mild days.
See skylights and roof replacement and roof flashing explained.