Broward County Certificate of Competency 20-WD-21968-X
What causes condensation or fog between the glass panes in an impact door?
A straight answer for Broward County homeowners, then what you can check yourself and when to call. Free estimate: (954) 906-1715.
Fog or condensation between the panes almost always means the perimeter seal of the insulated glass unit has failed. Humid outside air has gotten into the sealed gap, and the moisture-absorbing material inside is saturated. In Broward's heat, humidity and sun, that seal is under constant stress.
One nuance matters: moisture on the room-side or outdoor-side surface is a different problem. That is ordinary condensation from humidity and temperature differences, and it wipes off. Fog you cannot wipe away, because it sits inside the glass, is a seal failure.
Why the seal fails
Many impact doors use an insulated glass unit: two lites separated by a spacer, with a sealant around the edge and a drying agent inside. One or both lites are typically laminated glass, which is what gives the door its impact rating. Daily cycles of heat and cooling make the glass and frame expand and contract, and over time the edge sealant can crack or pull away. Intense UV speeds that aging.
Standing water is another cause. If a sliding door's sill or track drains clog, rain can sit against the bottom edge of the glass and work its way past the seal. Salt-air corrosion, a poorly set glass unit, or a manufacturing flaw can also open a path for moisture. Once the drying agent is used up, fog appears, usually first along the lower edge.
A hazy or cloudy look can also come from the laminated layer itself, such as edge delamination after long moisture exposure. That is a different failure from a seal leak, and a pro can tell the two apart on site. Since the glass is part of an opening-protection system, it is worth getting looked at rather than ignored.
What you can check yourself
Find which surface the moisture is on
Wipe the inside and outside faces with a dry cloth. If the fog stays, it is between the panes and the sealed unit has failed.
Note when it shows up
Fog that appears and clears with weather changes points to a leaking seal that is still partly working. Permanent haze suggests the drying agent is spent.
Look at the sill and track drains
Gently clear leaves and debris from sliding-door tracks and visible drain openings so rain is not pooling against the glass edge. Do not pry at the frame or glazing.
Check for cracks or edge damage
Look along the edges for chips, cracks, or separation between the glass and frame. Take photos for your records.
Gather the product details
Note when the door was installed and who installed it, and check for a manufacturer label. That helps determine what coverage the manufacturer or installer may offer.
When to call a pro
Fogged glass cannot be fixed with a household product. Do not drill into the glass or try to reseal it yourself. Call a pro if the fog is permanent, if you see cracks or delamination, or if the door also leaks at the sill, sticks, or won't lock. Doors serving a pool area should be checked too, since self-closing and self-latching hardware may be required under the pool barrier rules.
Because Broward is entirely in the High-Velocity Hurricane Zone, a replacement glass unit or door has to match an approved product, usually a Miami-Dade NOA, and be rated for the opening's design pressure. Whether a glass-only replacement needs a permit varies, so verify with your city's building department. Replacement of entire doors needs a permit, final inspection, and often condo or HOA approval. Our impact door and sliding door work falls under our Broward County Certificate of Competency 20-WD-21968-X. For a free estimate, call (954) 906-1715.
Impact Entry & Sliding Doors work is done under Broward County Certificate of Competency 20-WD-21968-X (windows, doors, shutters & garage doors).
What a pro will do
- Confirm the causeWe check whether it is a failed seal, laminate delamination, or surface condensation, and look for water pooling or frame damage.
- Identify the approved productWe find the door's approval and design-pressure rating so any replacement glass or door matches an approved assembly for the HVHZ.
- Repair or replaceDepending on the product and condition, that may mean replacing the glass unit or the whole door, with sill pans and flashing handled correctly.
- Handle the permitWhen the work needs a permit, we pull it, schedule the inspections, and close it out.
Related questions
- Does foggy glass make my impact door less safe in a storm?
- A fogged unit can still hold its laminated layer, but the failed seal means the assembly is no longer performing as approved. If the glass is also cracked or the frame is damaged, protection could be reduced in a strong storm. Have it inspected rather than assuming.
- Will foggy glass affect my wind-mitigation form?
- Opening protection is one category on form OIR-B1-1802, and a licensed inspector evaluates it across all openings. Florida law (s. 627.0629) requires insurers to offer wind-mitigation discounts, but what applies depends on your insurer and the inspector's findings. Our Wind Mitigation Credit Checker is a free place to start.
- Can the glass be replaced without replacing the whole door?
- Sometimes, if the frame is sound and an approved replacement unit exists for that product. Older or discontinued products may not have one. A pro can tell you after identifying the door's approval.
- Could the foggy glass be caused by a leaking sill?
- It can contribute. Water pooling at the bottom of the glass or in clogged track drains may speed seal failure, so the sill and flashing should be checked as part of any repair.
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