Florida Certified Roofing Contractor CCC 1334537
Why does my skylight only leak during heavy wind-driven rain?
A straight answer from a Florida certified roofing contractor — then what you can check yourself and when to call. Free quote: (954) 775-8990.
A skylight that leaks only in wind-driven rain almost always has a small gap in its flashing, sealant or roof tie-in that ordinary rain never reaches. Wind pushes water sideways and even upward, past the head and side flashings, into spots that gravity normally keeps dry.
The leak is not always the skylight itself. Water can enter the roofing around or above the unit and show up at the skylight's edge or light shaft, so the diagnosis has to follow the water path, not just the stain.
Why it happens
In a normal downpour, water runs down the roof and around the skylight. Flashing is built to shed that flow. In a strong storm, gusts drive water against the upslope (head) and side edges, and it can travel sideways under shingles or tile and past overlaps that are fine in calmer weather.
Sealant is a common culprit. Skylights flashed with caulk or roof cement instead of a proper flashing kit can hold up for a while, but Florida sun dries and cracks that sealant. The hairline gaps stay tight enough for light rain and open up only when water is pushed at them. Salt air near the coast can also corrode fasteners and metal flashing, and a loose or corroded piece creates the same kind of gap.
Other causes include a worn or shifted glazing gasket, a curb that is too low for the roof pitch, flashing that was never lapped correctly at the head, and debris trapped upslope that diverts water toward the unit. Because the leak needs wind from a certain direction, it can seem random for months. Noting which storms trigger it helps narrow down the cause.
What you can check yourself
Note the wind direction
Next time it leaks, write down which way the wind was blowing and which side of the skylight dripped. A pattern points to the flashing on that side.
Look from the ground
With binoculars, look for blobs of sealant, lifted or cracked flashing edges, or debris piled above the skylight. Stay off the roof.
Inspect the attic after a storm
With a flashlight, look at the framing around the skylight shaft for damp wood, water trails or stained insulation. Trails often start higher than the skylight, which suggests a roof-covering entry point.
Tell fogging from leaking
Moisture between the panes of glass means a failed seal in the unit. Water at the frame or ceiling only during storms points to flashing or the roof around it.
Check the ceiling and shaft
Look for stains on the drywall or the light shaft. Rings, bubbling paint or soft drywall mean water has been getting in for a while, even if it only shows up occasionally.
When to call a pro
Call a pro if you see stains that keep returning, soft or darkened drywall, wet framing in the attic, or sealant that has already been re-applied more than once. Repeated caulking rarely fixes a flashing problem. A leak left alone can also soak the roof deck and framing around the opening.
Here is what Florida requires: "Roofing work in Florida legally requires a licensed roofing contractor and generally a permit from the local building department; a contractor's license is verified on the Florida DBPR website." Skylight replacements usually involve a permit as well, so confirm the details with your local building department. We are roofing specialists, and you can reach us at (954) 775-8990 for a free estimate.
What a pro will do
- Diagnose the actual water pathWe check the flashing, curb, glazing seals and the roof covering above the unit, so the repair fixes the entry point rather than the visible stain.
- Replace sealant-only fixes with proper flashingA correctly sized flashing kit for a curb-mounted or deck-mounted unit, lapped properly at the head and sides, replaces dried-out caulk.
- Replace failed units when neededA cracked, fogged or worn-out skylight is replaced with a unit suited to the site, including impact-rated options where required.
- Repair the damage underneathRotten plywood and fascia replacement is included in our scope. Permits are pulled under our license, inspections are scheduled and passed, and the job is cleaned up. The written flat rate quote says what is included.
Related questions
- Can I just add more sealant around the skylight?
- Extra sealant may stop a drip briefly, but it is the same material that tends to dry and crack in Florida sun. If the flashing is the problem, a proper flashing kit is the lasting fix.
- Does a replacement skylight need to meet wind or impact requirements?
- Florida Building Code requirements for glazing in the wind-borne debris region generally apply, and units need a product approval with ratings suited to the site. As the rule reads: "Miami-Dade and Broward are Florida's High-Velocity Hurricane Zone. Roofing products used there need a Miami-Dade Notice of Acceptance (NOA) for that use; elsewhere in Florida they need a Florida Product Approval (or local approval). Either way the product is installed per its approval."
- Is the leak from the skylight or from the roof around it?
- It can be either. Water often enters through the shingles, tile or flashing near the unit and then follows framing to the skylight shaft. That is why a diagnosis traces the water path before anything is replaced.
- Why do skylight leaks seem to show up in summer?
- Summer thunderstorms often bring gusty wind with heavy rain, which tests flashing in ways calm rain does not. Leaks can also show up after tropical storms.
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