Florida Certified Roofing Contractor CCC 1334537
Why is there condensation on the inside of my skylight every morning?
A straight answer from a Florida certified roofing contractor — then what you can check yourself and when to call. Free quote: (954) 775-8990.
Condensation on the room-side surface of a skylight in the morning is usually humid indoor air meeting glass that cooled overnight. A skylight is often the coldest surface in the room, so moisture in the air settles there first. It is common and is not always a sign that the skylight is leaking or failing.
The nuance is where the moisture sits. If it forms on the inside face and wipes away, it is a humidity issue. If it is trapped between the panes and you cannot wipe it off, the sealed glass unit has failed and the unit usually needs replacing. Water stains, drips or damp drywall around the frame point to a leak, which is a different problem.
Why it happens
Air holds moisture, and cooler surfaces make that moisture turn to droplets. Overnight the glass drops below the temperature of the room air, and the moisture shows up as a film or beads by morning. It usually clears as the sun warms the glass. Florida's high year-round humidity gives indoor air plenty of moisture to release, and showers, cooking, drying laundry and many people sleeping in a closed room add more.
A skylight in a bathroom, kitchen or stairwell sees more of this than one in a dry hallway. Poor ventilation makes it worse. So can a bath fan or dryer vent that discharges into the attic instead of outdoors, which can also push damp air back toward the ceiling opening.
Condensation between the panes is a separate cause. Modern skylight glass is a sealed unit, and over time the seal can fail. Humid air gets in, and you see fogging, haze or droplets inside the glass that no cleaning reaches. Once the seal has failed, the unit's insulating performance is reduced and the condensation will keep coming back.
What you can check yourself
Try the wipe test
From inside, wipe a damp spot with a dry cloth. If it comes off, it is on the room-side surface. If the fog stays, it is likely between the panes.
Note when it appears and clears
Condensation that shows up early and fades as the sun hits the glass points to indoor humidity. Fogging that is there all day suggests a failed seal.
Look at the ceiling and shaft
From below, check the light shaft, the drywall around the opening and the frame for stains, bubbling paint, mildew or soft spots. These suggest water getting in, not just condensation.
Check your ventilation
Make sure bath and kitchen fans run during and after use and vent outdoors. A ceiling fan or the air conditioning running overnight can lower indoor humidity.
Check the attic side if you can reach it safely
From the attic access, look at the skylight's shaft and nearby decking for damp insulation, dark staining or drip marks. Do not go on the roof.
When to call a pro
Call us if the fog is trapped between the panes, if there are stains or drips around the frame, or if the moisture keeps coming back after you have improved ventilation. Sealant used in place of proper flashing can dry out in the Florida sun, and wind-driven rain can find the head and side flashings. A leaking skylight that gets only a cosmetic fix can let moisture reach the framing and decking over time.
Skylight work tied into the roof is roofing work. Florida's rule is: "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 required for skylight replacements as well, because framing, flashing and ratings are inspected, so confirm the details with your local building department.
What a pro will do
- Diagnose the causeWe look at whether this is room-side condensation, a failed sealed unit or a leak at the flashing, so you are not replacing a unit that only needs better ventilation.
- Replace failed or fogged unitsIf the glass seal has failed, we replace the unit, using the correct flashing kit for a curb-mounted or deck-mounted skylight, and consider impact-rated units where they suit the site.
- Repair or rebuild the flashingWhere sealant has been used in place of proper flashing, we replace it with a proper flashing assembly instead of adding more sealant.
- Handle permits and cleanupWe pull the permit under our own license, schedule and pass the inspections, close out the permit and clean up. Rotten plywood and fascia replacement is included in the scope.
- Coordinate with a re-roofIf a roof replacement is already planned, the skylight can be done at the same time so the new roof is flashed in around it.
Related questions
- Is skylight condensation harmful?
- A little morning condensation that clears on its own is mostly a sign of humid indoor air. If it runs onto the frame or drywall regularly, it can stain paint and encourage mildew, so it is worth fixing the cause.
- Can a fogged skylight be cleaned?
- Not if the fog is between the panes. That moisture is inside the sealed unit, so cleaning the surfaces will not remove it. The unit generally needs replacing.
- How do I tell condensation from a leak?
- Condensation tends to appear as a film or droplets over the glass at certain times of day. A leak usually shows up as drips, staining or damp material at the frame or light shaft, often after rain.
- What does a skylight quote from you include?
- We give a free estimate and a written flat rate quote that says what is included. To get one, call (954) 775-8990 or use the estimate form on the page. The phone is answered around the clock, and the office keeps weekday hours, Monday to Friday, 8am to 6pm.
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