Florida Certified Roofing Contractor CCC 1334537
What does it mean when my skylight looks foggy between the panes?
A straight answer from a Florida certified roofing contractor — then what you can check yourself and when to call. Free quote: (954) 775-8990.
Fog between the panes almost always means the airtight seal around the double-pane glass unit has failed. Humid air has gotten into the gap, and moisture now condenses on the inside faces of the glass where you can't wipe it away.
The fog itself is not a roof leak, and it doesn't mean the skylight is about to fall apart. But a failed seal doesn't repair itself, and the fix is replacing the glass unit or the whole skylight, not cleaning. It is also worth checking whether the flashing around the skylight is leaking, since the two problems can show up together.
Why a skylight fogs inside
A sealed skylight unit is two layers of glazing with a sealed gap between them, usually with a drying agent built into the edge. When the edge seal breaks down, that gap starts trading air with the outside. The drying agent eventually can't keep up, and moisture shows up as fog, haze, droplets or a mineral film.
Skylights take a lot of punishment. Direct sun heats the glass and frame, then a summer thunderstorm cools it quickly. In Florida's hot, humid climate, that repeated expansion and contraction can wear down edge seals over time. Water that gets past the flashing and sits against the frame can also attack the seal from the outside.
Fogging is different from ordinary condensation on the room-side surface, which comes from indoor humidity and wipes away. If the haze is inside the glass sandwich, the unit has failed. If the fog is on the surface you can touch, look at indoor humidity and ventilation first.
What you can check yourself (from the ground and indoors)
Wipe the room-side glass
Wipe the underside of the skylight with a dry cloth. If the haze stays, it is between the panes and the seal has failed. If it wipes off, you're dealing with indoor condensation.
Look at the pattern over a few days
Fog that comes and goes with the weather but never fully clears points to a failed seal. Droplets, streaks or a chalky film inside the glass point the same way.
Check the ceiling and light well
Look for stains, bubbling paint, drips or soft drywall around the skylight opening, especially after a rainstorm. These suggest water is getting in at the flashing, not just through a failed seal.
Peek into the attic if it is accessible
From a safe spot at the attic access, look for damp insulation, dark stains or wet wood near the skylight shaft. Don't walk on the roof or climb a ladder to inspect it.
Take photos
Photograph the fog and any stains, with the date. They make it easier to get an accurate quote and to show whether things are changing.
When to call a pro
A fogged unit is worth having looked at, because the fix means removing glass or the whole unit and working at the roof flashing. If you also see stains, drips or damp insulation, the flashing is a likely suspect and should be diagnosed along with the glass. Sealant smeared around a skylight in place of proper flashing can dry out in the Florida sun and stop doing its job.
Skylight replacement generally involves the roof, so the licensing rule applies. Here is the exact wording from our site facts: "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." A permit is typically needed for skylight replacements as well, since flashing and pressure or impact ratings are inspected. Confirm the details with your local building department.
We can look at it with you. Call (954) 775-8990; the phone is answered around the clock, and the office keeps weekday hours, Monday to Friday, 8am to 6pm.
What a pro will do
- Diagnose the fog and any leakWe check whether the glass seal alone has failed or whether the flashing, curb or surrounding roofing is also letting water in.
- Replace the failed unitDepending on the skylight, that means a new glass unit or a full replacement. Curb-mounted and deck-mounted units each get the correct flashing kit.
- Choose a rated replacementFlorida Building Code glazing rules for wind-borne debris regions apply, and skylight units need Florida Product Approval with ratings suited to the site. In Broward and Miami-Dade, Miami-Dade NOAs are generally required.
- Handle the permit and repair damageWe pull the permit under our own license, schedule and pass the inspection, and close out the permit. Rotten plywood found around the opening is replaced as part of the scope.
- Clean upThe old unit and debris are hauled away. If a re-roof is coming, the skylight can be done at the same time.
Related questions
- Can a fogged skylight be fixed without replacing it?
- Not reliably. Once the seal has failed, the gap can't be cleaned or resealed from the outside in any lasting way. The sealed unit generally needs to be replaced, either alone or with the whole skylight.
- Does a foggy skylight mean my roof is leaking?
- Not necessarily. Fogging comes from a failed glass seal, while a leak comes from the flashing or the roof around it. Check the ceiling and attic for stains, and have someone diagnose both at once if you see them.
- How much does it cost to replace a fogged skylight?
- It depends on the skylight size, the type of mount, roof access, the material and rating of the new unit, permit requirements, and what we find once the old unit is out, such as damaged decking. We give a free estimate and a written flat rate quote that says what is included.
- Should I wait for the dry season to replace it?
- Fogging alone is not usually urgent, and replacements are often bundled with dry-season reroofing. If you see staining or drips, though, don't let a leak sit through the rainy season. Call us and we'll sort out what is going on.
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