Foggy Impact Windows in Florida: Why They Fog & How to Fix It (2026)
If your impact window looks cloudy or has moisture trapped between the panes that you can't wipe off, the sealed glass unit has failed. Here's why it happens in South Florida, whether you still have hurricane protection, and the cheapest correct way to fix it.
The short answer
Fog between the panes = a failed insulated glass unit (IGU) seal. The window isn't broken — but the sealed unit no longer works. The right fix is replacing the glass unit only (not the whole window), which is far cheaper. Often it's covered by warranty.
Why Impact Windows Fog Up Between the Panes
An impact window is built from an insulated glass unit (IGU): two panes of glass separated by a spacer, sealed around the perimeter, with dry air or argon gas in the gap. The seal keeps Florida's humid air out and the insulating gas in. When that perimeter seal fails, humid air seeps into the gap and condenses — producing the fog, haze, or water droplets you see inside the glass that no amount of cleaning removes.
Age & heat cycling
Florida's daily heat expansion and contraction slowly fatigues the perimeter seal. Most IGU seals last 10–20 years; coastal heat shortens that.
Manufacturing defect
A weak or incomplete factory seal can fail within a few years — usually covered by the glass warranty.
Lost argon / desiccant saturation
The spacer holds a desiccant that absorbs trace moisture. Once it saturates, humidity condenses inside the gap and fog appears.
Improper installation stress
Glass installed with the wrong shims or pressure can stress the seal corner and cause early failure — a workmanship issue.
Do You Still Have Hurricane Protection?
Mostly — but don't ignore it. The laminated impact pane still holds together and resists impact, so a foggy-but-uncracked window generally keeps its physical hurricane resistance. The problems a failed seal creates are slower:
- Trapped moisture can corrode the laminated interlayer bond over years.
- A failed seal usually voids the glass warranty if not addressed.
- You lose the insulating gas, so energy efficiency drops and AC bills rise.
Bottom line: it's not an emergency like a cracked pane, but plan the glass replacement before the seal failure spreads or hurricane season arrives.
How to Fix a Foggy Impact Window
Glass-only IGU replacement (the right fix)
Replace just the sealed glass unit while keeping the existing frame. Restores the seal, the gas fill, the energy rating, and the warranty path.
- • Possible when the frame is sound (almost always with fog)
- • Far cheaper than a whole new window
- • In-stock units install in days, not months
"Defogging" services (not recommended)
Some companies drill the glass, clean it, and add a vent. It may clear the haze temporarily but:
- • Does not restore the seal or argon fill
- • Does not restore the energy rating
- • Not appropriate for laminated impact glass
What Does It Cost?
| Option | Typical cost (South FL, 2026) |
|---|---|
| Glass-only IGU (unit + labor) | $250–$600 total, by size & glass type |
| Under manufacturer warranty | Often $0 for the unit — labor may apply |
| Full window replacement (if frame is bad) | $500–$900+ installed |
| In-stock glass via Windows Stock Market | 30–60% below custom factory price |
Send us the window size and a photo of the fog and we'll quote the exact replacement unit — free.
Frequently Asked Questions
Why are my impact windows foggy between the panes?
Fog between the panes of an impact window means the insulated glass unit (IGU) seal has failed. Impact windows use two panes of glass with a sealed air or argon gap between them. When the perimeter seal breaks down — from age, heat cycling, or a manufacturing defect — humid Florida air gets inside the gap and condenses into fog or moisture you cannot wipe away. The glass itself is not 'broken,' but the sealed unit no longer works. The fix is replacing the glass unit, not the whole window.
Do foggy impact windows still protect against hurricanes?
Mostly yes, but with a caveat. The laminated impact pane still holds together and resists impact, so a foggy window with no cracks generally retains its physical hurricane resistance. However, a failed seal can let moisture corrode the interlayer bond over time and may void your product warranty. It also signals the unit is aging. You should replace the glass before the seal failure spreads or the interlayer degrades — ideally before hurricane season.
Can you fix a foggy window without replacing the whole window?
Usually yes. When the frame is sound and only the seal has failed, you replace just the insulated glass unit (IGU) — a 'glass-only' replacement — which costs far less than a new window. 'Defogging' services that drill and vent the glass exist, but they do not restore the seal, the gas fill, or the energy rating, and are not recommended for impact windows. The proper fix is a new sealed IGU. Windows Stock Market supplies replacement impact glass units by size. Call (754) 303-7130 for a free assessment.
How much does it cost to replace a foggy impact window glass unit in South Florida?
A glass-only IGU replacement typically runs $150–$400 for the unit plus $100–$200 labor, depending on size and glass type — far less than $500–$900+ for a full window. Buying the replacement glass in-stock through Windows Stock Market cuts the material cost 30–60% versus a custom factory order. Send the size and a photo for a fast, free quote.
Is window fogging covered by warranty?
Often, yes. Seal failure (fogging) within the manufacturer's glass warranty period is one of the most commonly covered defects — PGT, ESW, and Mr. Glass all warranty their insulated glass units against seal failure for a set number of years. Contact the original installing contractor, who handles the warranty claim. If the window is out of warranty, a wholesale in-stock IGU replacement is the most affordable fix.
How long can I wait to fix a foggy impact window?
There is no immediate safety emergency from fog alone (unlike a cracked or broken pane), but you should not wait indefinitely. A failed seal lets in moisture that can fog permanently, grow mineral deposits between the panes, and slowly degrade the laminated interlayer. It also kills your energy efficiency. Plan the glass replacement within a few months, and before hurricane season if the unit is older.