Why Are My Windows Fogging Up Between the Panes
Fog or condensation trapped between two panes of glass means the seal on that insulated glass unit has failed and moist air has entered the gap — this is not a surface cleaning issue, and it isn’t cleanable. The sealed unit needs to be replaced.
See full window replacement options and cost if this is happening on multiple windows.
How to Tell Which Path You’re On Before Calling Anyone
Check for a manufacturer sticker or etching in the corner of the glass, which often includes a date code. If you have that, a window company can usually tell you over the phone or from a photo whether a matching sealed unit is still available, saving you an in-person visit just to get that answer. If there’s no visible marking and the window is more than 15 years old, it’s reasonable to assume full replacement is the more likely outcome and plan the conversation accordingly.
Sealed Unit Replacement vs. Full Window Replacement
If the frame is otherwise sound, many window brands allow just the glass unit to be swapped without replacing the whole window — this runs less than a full replacement, if the manufacturer still supports that part for your window’s age and model. Windows older than about 15-20 years often can’t get a matching replacement unit, which pushes the repair toward full window replacement instead.
What Not to Do in the Meantime
Don’t attempt to drill a small hole to “let the moisture out” as a temporary fix — this is sometimes suggested online, but it permanently damages the sealed unit’s insulating performance and doesn’t solve the underlying seal failure.
Why This Happens More in Wilson’s Climate
The argon or air gas between panes is meant to stay sealed for the window’s lifespan, but Wilson’s summer humidity and heat cycling puts more stress on that seal than a drier, milder climate would. Once even a microscopic gap develops in the seal, humid outside air gets pulled into the temperature-differential gap between panes and condenses — you’ll typically see it worst on hot, humid afternoons and it may partially clear on cooler, drier days, which confuses people into thinking it’s intermittent rather than a permanent failure.
Warning: Don’t confuse pane-gap fogging with condensation on the inside surface of the glass, which is a completely different (and usually easy) fix related to indoor humidity and ventilation, not the window itself. If you can wipe the moisture away with a cloth on the inside, that’s not a seal failure.
Common Questions
Why is there fog trapped between my window panes?
The seal on that insulated glass unit has failed and let moist air into the gap. This isn’t a cleaning issue — it’s permanent, and the sealed unit needs replacement.
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Wilson Exteriors Pro is an independent local information and referral service. We are not a licensed contractor and do not perform siding or window installation ourselves. Project requests submitted through this site may be shared with an independent, licensed local contractor for a free estimate.
