If you see fog or moisture trapped between the panes, the insulated glass unit (“thermos”) may have failed. In many cases, replacing the glass unit can restore clarity and insulation without changing the entire frame.
Most modern windows use an insulated glass unit (IGU) — two (or more) panes sealed together to improve insulation. When that seal fails, moisture can get trapped between the panes, leading to fogging, streaks, or a cloudy appearance.
Common Signs of Failure
Fog, haze, or moisture trapped between the panes
Cloudy appearance that you can’t wipe off from inside or outside
Visible streaks or “milkiness” inside the glass unit
Reduced comfort near the window (drafts can also be a sealing issue)
Condensation Between Panes vs. On the Surface
Not all condensation means the thermos has failed. If the condensation is between the panes, it often indicates a failed seal. If it’s on the interior surface, it can be related to indoor humidity or ventilation.
We’ll inspect your situation and recommend the most practical fix.
Repair or Replace?
We’ll explain both options clearly so you can choose what’s best for your home and budget.
Smart Option: Thermos Replacement
Cost-effective solution when the window frame and overall structure are in good condition, and the main issue is just the sealed glass unit.
Frame is solid and not damaged
Operation hardware works well
Primary issue is fogging/haze
Restore clarity without construction mess
Full Window Replacement
In some cases, replacing the entire window makes more sense to ensure long-term performance and fix underlying issues.
Damaged or deteriorated frames
Draft or water leaks related to structure
Hardware is broken or hard to operate
Need for style or energy upgrade
Thermos Replacement — FAQ
Can you fix foggy windows?
In many cases, yes. Fogging between panes often points to a failed sealed unit (“thermos”), and replacing the insulated glass unit may restore clarity and insulation.
Do I need to replace the entire window?
Not always. If the frame and overall window condition are good, thermos replacement can be a practical option. We’ll assess and recommend the best approach.
How do I know if condensation is between the panes?
If the cloudiness can’t be wiped off from inside or outside and looks trapped within the glass, it may be between the panes. An inspection confirms it.
Will thermos replacement improve comfort?
It can help restore insulation performance when the sealed unit has failed. Overall comfort also depends on installation, sealing, and window condition.
Do you offer repair, sales, and installation?
Yes — we provide repair, sales, and installation depending on your needs.
Are you RBQ licensed?
Yes — RBQ 5799-3610-01.
Get a Free Thermos Replacement Quote
Send us a photo of the fogging and tell us how many windows are affected. We’ll respond quickly with the next steps and a clear recommendation.
