A temporary cosmetic fix. Defogging removes the cloudiness, but it does not restore the inert gas . You’ll still have poor insulation. Worse, the seal is still broken, so fog usually returns within 1–3 years. We do not recommend this for energy savings. Option 2: Seal Replacement (Partial repair) In rare cases, if the frame is perfect and only the sealant failed, a glazier can remove the glass unit, clean the spacer, and apply new sealant.
This is almost as labor-intensive as full replacement and often fails again quickly. Most professionals won't offer this. Option 3: Glass Unit Replacement (The real fix) This is the gold standard. You keep your existing window frame (sash) but replace only the insulated glass unit. A glazier removes the old IGU, orders a new one custom-sized, and installs it. double paned window repair
When the seal is perfect, the window keeps warm air out in summer and heat inside in winter. The most common issue isn't broken glass—it's a broken seal . Over time, sun exposure, building settlement, and temperature swings cause the seal to fail. Moisture from the outside air enters the space between the panes. A temporary cosmetic fix
| Repair Type | Average Cost per Window | Energy Savings Restored? | | --- | --- | --- | | Defogging | $60 – $100 | No | | IGU Replacement (glass only) | $200 – $400 | Yes | | Full window replacement | $600 – $1,200+ | Yes | Worse, the seal is still broken, so fog
If you have 10 foggy windows, IGU replacement at $300 each = $3,000. Full replacement could be $8,000+. You can see why glass replacement is appealing. Do not try to separate the glass panes yourself. A broken seal exposes the sharp edges of the spacer and glass. Moreover, if your window was made before 2000, the spacer may contain desiccant (silica gel) that is caustic. And if the unit ever had a lead-based coating? You’ll create a toxic dust.