06/01/2026
Noticing fog between the panes and wondering if you really need a whole new window?
Here’s the simple truth: if the moisture is trapped inside the glass unit, the seal has failed. That means the insulated glass unit, or IGU, is no longer doing its job.
What to know:
1. A glass-only replacement can save you money
If the frame is still in good shape, replacing just the glass unit can cost 50 to 70% less than replacing the entire window.
2. The frame matters just as much as the glass
Before choosing repair, check whether the frame is square, the sash opens and closes properly, and the weep holes are clear. If the window is warped or damaged, a full replacement may be the smarter fix.
3. Fog is not just a cosmetic issue
Once the seal fails, insulation performance drops. That can mean less comfort and more energy loss over time.
4. Replacement is not always the best answer
A lot of homeowners are told to replace the whole window right away, but that is not always necessary. Sometimes the honest solution is the smaller one.
Practical takeaway: if you see fog between panes, ask a pro to inspect the frame first. If the structure is sound, a glass-only swap may be the most cost-effective repair.