A skylight that drips is either leaking through its flashing or collecting condensation on cold glass, and the two need opposite fixes. Drips during rain or snowmelt point to flashing: a kit that does not match the roof, too little flange on the uphill side, debris piled behind the curb, or sealant that blocks the path water is meant to take. Drips on cold, dry days point to indoor humidity meeting cold glass. This page is general information; your roofer and building department make the final call.
On this page: Leak or condensation? · Causes · Safe checks · Repairs · Code basis · When to call
Leak or condensation?
| Clue | Points to a flashing leak | Points to condensation |
|---|---|---|
| When it drips | During or after rain or snowmelt | Cold mornings with no rain |
| Where it shows | Staining on one side of the light shaft, often uphill | Water on the glass and frame, dripping evenly |
| Which room | Any room | Bathrooms and kitchens most often |
| What helps | Reflashing | Running the exhaust fan, lowering indoor humidity |
Why skylight flashing fails
- Wrong flashing kit. A kit made for a different roof covering, or a generic kit on an old unit.
- Self-flashing units with a short uphill flange, so the backer flashing cannot tuck far enough under the shingles above.
- Low curbs on flatter roofs, where water and snow sit against the frame.
- Sealant used as a dam. Caulk that blocks the channels water is meant to drain through.
- Blocked weep holes and leaves or needles packed against the uphill side.
- Failed glass seals, which show as fog between the panes.
What you can check yourself
Do it from inside and from the ground; stay off the roof.
- Keep a log. Note the weather each time it drips. That one habit separates leaks from condensation better than anything else.
- Look at the glass. Fog between the panes means the seal has failed. Beads of water on the room side on a cold day mean condensation.
- Check the light shaft. Stains on drywall around the shaft, especially on the uphill side, suggest water getting past the flashing.
- From the ground, with binoculars, look for leaves or needles piled behind the skylight and for caulk smeared around the curb.
Repair options, from small to full
| Repair | When it fits |
|---|---|
| Clear debris and weep holes; remove sealant that dams drainage | Recent drips, unit in good shape. |
| Reflash with the manufacturer’s matched kit, including side step flashing and an uphill backer or cricket | Flashing is generic, damaged or installed wrong. |
| Replace the unit and its flashing together | Fogged or cracked glass, an aging frame, or a reroof. |
| Improve room ventilation | The problem is condensation, not a leak. |
Fixes that fail: caulking the glass-to-frame joint or the curb, reflashing an old skylight with a generic kit, and adding a bead of sealant along the uphill side to “hold back” water.
Code and industry basis
NRCA’s Professional Roofing guidance on skylights says steep-slope units should be flashed like chimneys, with apron, step, cricket or backer, and counterflashing pieces, and that self-flashing units often need added step flashing and a properly sized backer. It suggests about a 4-inch curb on steep slopes and enough curb for an 8-inch base flashing on low-slope roofs, and it explains that condensation forms when the glass or frame falls below the dew point of the room air.
The 2024 IRC, section R903.2.2, exempts unit skylights flashed per the manufacturer’s instructions from the cricket rule that applies to wide penetrations, which is why the manufacturer’s kit matters. A 2024 Roofing magazine summary of the AAMA 1607 installation guide warns that sealant used to dam water paths makes leaks worse.
When to call a roofer
Call if drips match the rain, if you see stains around the shaft, or if the glass is fogged and the roof is getting older. A skylight problem caught early is usually a reflash. Left alone, it can rot the curb and the deck around it. If your log points to condensation, you may not need a roofer at all. Related guides: chimney flashing, pipe boots, and attic frost. The roof problems guide lists the rest.
Schedule a skylight inspection
Integrity Roofing and Painting is veteran-owned and family-run since 1990, an Owens Corning Platinum Preferred contractor with 650+ Google reviews. We tell you whether the skylight is worth reflashing or ready to be replaced, with photos of the curb and flashing. Call (719) 488-2800 in the Colorado Springs area or book a free inspection; (303) 209-0152 in the Denver metro or book a free Denver inspection; or (512) 610-5897 in Austin for a free Austin inspection. Expect a reply the same business day.
Sources: Professional Roofing (NRCA), Shedding some light on skylights (2002); 2024 IRC Chapter 9, section R903.2.2 (UpCodes); 2024 IRC Chapter 3, section R324.6.8 (UpCodes); Roofing magazine, A roofer's guide to installation best practices (2024).
