Problems
Foggy or Failed Insulated Glass (IGU)
Foggy glass between the panes usually means the insulated glass unit, or IGU, has lost its seal. We help you understand what that means and connect you with a licensed commercial glazing contractor at no cost.
What a failed IGU means
An insulated glass unit is two or more panes of glass sealed together with a space in between. That space is usually filled with air or gas to help with insulation and comfort.
When the seal fails, moisture can get inside the unit. That often creates fog, haze, or water droplets between the panes. The glass may still be in place, but its performance is reduced.
This is common in commercial windows, storefronts, curtain wall systems, and other architectural glazing. It is not the same as surface dirt or outside condensation.
Why it happens
IGU seals can break down over time because of age, sun exposure, weather, building movement, or prior installation issues. Temperature swings can also stress the edge seal.
If the unit has low-E coatings, gas fill, or specialty glass, the failure may affect energy performance as well as appearance. In some cases, the problem is limited to one pane; in others, the whole IGU needs replacement.
A licensed commercial glazing contractor can inspect the unit and determine whether the glass can be replaced as a unit, whether hardware or framing is contributing to the problem, and what scope is appropriate for the building.
Signs it may be a seal failure
Fog or moisture between the panes is the most common sign. The haze may come and go at first, then remain visible.
You may also notice mineral spots, streaking, or a milky look that cannot be wiped off from either side. If the unit is damaged, you may see cracked glass, failed edge seal material, or other visible wear.
Important: if the glass is cracked, loose, or unsafe, treat it as a building issue that should be reviewed promptly by a licensed, insured glazing contractor.
Repair, replace, or reseal?
In most commercial projects, a failed IGU is not repaired by cleaning or patching the fog. The sealed unit usually needs to be replaced.
The right scope depends on the system type. Storefront glass, curtain wall, and window wall assemblies are built differently, and replacement can vary by frame, size, access, and glass make-up. Safety glass rules may also apply.
If you need a clearer picture of the process, see our services page for the kinds of commercial glazing projects we help coordinate, or review typical costs to understand common pricing factors.
How our free matching service works
Paneworks is not a glazing company. We do not inspect, fabricate, install, or repair glass ourselves.
We help you find a licensed, insured commercial glazing contractor for the job at no cost to you. Share the project basics, and we connect you with a contractor who can review the scope and provide a bid.
To get started, use our get matched page and send the project location, type of glazing system, approximate size, and your contact details. If you prefer, you can include an email or language preference.
If the fog is between the panes, the insulated glass unit has likely failed and usually needs replacement by a licensed commercial glazing contractor.
Common questions
Can foggy glass between the panes be cleaned?
Usually no. If the fog is inside the insulated glass unit, the seal has likely failed and the moisture is trapped between the panes. A commercial glazing contractor can confirm whether the unit needs replacement.
Is a failed IGU a safety issue?
Not always, but it can become one if the glass is cracked, loose, or part of a high-traffic area, railing, or overhead condition. Heavy glass and code requirements make it important to have a licensed pro review it.
Do I need to replace the whole window system?
Not necessarily. In many cases, only the insulated glass unit is replaced. The frame, gaskets, and surrounding system should still be checked to make sure they are in good condition.
How much does commercial IGU replacement cost?
Costs vary by size, access, glass type, coating, and system. Typical pricing can differ a lot by jurisdiction and project conditions, so a contractor bid is the best way to get an accurate number.
How fast can I get help?
That depends on your project details, location, and contractor availability. We can help you start the matching process quickly, but we do not guarantee a timeline or outcome.