Skylights put a hole in the roof on purpose, so every one depends on flashing and seals to stay dry. Start by finding out whether you have a leak at all.
Is it a leak or condensation?
Watch when the water shows up.
| What you see | Likely cause |
|---|---|
| Drips during or right after rain, worse in wind-driven storms | Leak at the flashing, curb or seal |
| Water on the glass on cool mornings, with no rain | Condensation |
| Stain on the ceiling around the light well, growing after storms | Leak, often at the upslope side of the curb |
| Water between the panes of a double-glazed unit | Failed glazing seal |
| Visible crack or crazing in a plastic dome | Lens failure |
Condensation forms when humid indoor air meets the cooler glass. Running a bathroom fan or lowering indoor humidity reduces it. A leak needs a roof repair.
Where do skylights leak?
Check these four spots, in this order.
- The upslope side of the curb. Water running down the roof hits the skylight first here. Debris and leaves collect behind the curb and hold water against the flashing.
- Step or counterflashing along the sides. Rusted, lifted or short metal lets water past.
- The seal between lens and frame. Older dome units rely on gaskets and sealant that harden and crack in UV.
- The lens. Plastic domes can craze and crack with age, and glass can break from impact.
On a tile roof, the surrounding tiles have to come off to reach the flashing and the underlayment beneath it. See our tile roof underlayment guide for why the layer under the tile matters.
Which code sections cover a skylight repair?
Several sections apply, and a correct repair should meet them.
- Curbs on low slopes. Florida Building Code section R308.6.8 requires unit skylights on roofs flatter than 3 in 12 to be mounted on a curb at least 4 inches above the roof plane, unless the manufacturer's instructions say otherwise.
- Testing and labels. Section R308.6.9 requires unit skylights and tubular daylighting devices to be tested by an approved independent laboratory and labeled for compliance with AAMA/WDMA/CSA 101/I.S.2/A440.
- Flashing. Section R903.2.1 requires flashing around roof openings. Section R903.2.2 lets unit skylights skip a cricket or saddle if they are flashed according to the manufacturer's instructions.
- Reroof rules. Section R908.5 bars reinstalling metal counterflashings, collars and similar flashing that is rusted, damaged or deteriorated. Section R908.6 requires flashings to be reconstructed according to approved manufacturer's installation instructions.
- Product approval. Florida Statutes section 553.842 puts skylights on the list of products that need approval before they go on a Florida home.
Should I reflash, repair or replace the skylight?
Match the fix to what failed.
| Situation | Best fix |
|---|---|
| Unit is sound, water enters around it, flashing is rusted or loose | Reflash with a flashing kit made for that unit |
| Leak at the lens seal on an otherwise solid unit | Reseal or replace the gasket if the manufacturer offers one |
| Cracked or crazed dome, fogged glass, rotted frame | Replace the skylight and its flashing together |
| Roof is being replaced and the skylight is aging | Replace during the reroof |
| You no longer want the skylight | Remove it, frame the opening, and deck and roof over it |
Reflashing a good unit is the smaller job. Replacement makes more sense when the unit is old enough that its seals will fail soon after the new flashing goes on. Flashing work falls in our common repair range of $350 to $1,500, which covers leaks, flashing and pipe boots. A full skylight replacement depends on the unit, so we quote it after seeing the roof and the light well.
Is it worth replacing a skylight during a reroof?
Usually, if the unit is aging or its lens is cloudy. The flashing comes off during the reroof anyway, and the code will not let rusted or deteriorated metal go back on. Paying for new flashing around an old unit, then opening the roof again later to replace that unit, means doing the flashing twice.
If the skylight is newer and in good shape, it can stay. Ask your roofer to confirm the replacement flashing matches the skylight maker's instructions.
What should I do while the skylight is leaking?
Set a bucket or towels below the light well and shift furniture or rugs out of the way. Photograph the ceiling and, if you can safely look, the attic side of the light well. Do not climb onto a wet roof. Our roof leak guide walks through the first hour, and roof repair vs replacement helps if the skylight is one of several problems.
Book a roof leak repair visit and we will find where the water is getting in before recommending a fix.
