Skylight leaking

Symptoms

• Water stains on the ceiling around the skylight
• Drips during or after rain
• Musty smell in the room below
• Visible gap or cracked sealant around the frame from outside

Likely causes

• CommonFailed flashing where the skylight meets the roofFlashing seals age, corrode, or shift, letting water track along the roofline into the ceiling.
• CommonCracked or dried-out exterior sealant/caulkUV exposure breaks down sealant faster on a roof than on walls.
• PossibleCondensation mistaken for a leakEspecially in winter, condensation on the inside of the skylight can drip and look like a roof leak.
• PossibleCracked skylight glazing or domeImpact or age can crack the glass or plastic dome itself.
• Less commonClogged skylight drainage channel (on curb-mounted units)Debris can block the small channels designed to shed water away from the seal.

What to do

1. Check inside first: if moisture appears only in cold weather without rain, it may be condensation rather than a leak.
2. Look at the ceiling drywall pattern of the stain; water often travels before dripping, so the leak point may not be directly above the stain.
3. From the ground or with binoculars, look at the flashing and caulk line around the skylight for visible cracks or lifted edges.
4. Do not climb onto the roof yourself if it's steep, wet, or you're not experienced with roof work.
5. For accessible ground-level or single-story skylights, a small bead of roofing sealant over an obviously cracked caulk line can be a stopgap.
6. Photograph any interior staining and note when leaks occur (during rain, after snow melt, etc.) to help a roofer diagnose it.
7. Schedule a roofer to inspect and reflash or reseal the skylight, since improper flashing repair often leads to repeat leaks.

Tools and parts

• Flashlight
• Binoculars (for inspection only)

When to call a pro

Call a roofer for any skylight leak, since proper flashing repair requires roofing experience and the right materials.

Safety