Glass-Only Replacement: When You Can Replace Just the Glass Unit

Between defogging and full window replacement, there's a middle option: replacing just the insulated glass unit (IGU) while keeping the frame.

What Glass-Only Replacement Involves

According to FGIA, glass-only replacement means:

1. Removing failed IGU from existing frame
2. Installing new IGU with fresh seals and gas fill
3. Re-glazing and weatherstripping as needed

The frame, sash, and hardware stay in place.

When It Works

According to GANA, glass-only replacement makes sense when:

Frames are in good condition: Vinyl, fiberglass, or aluminum frames with no warping, cracking, or deterioration

Hardware functions properly: Locks, hinges, and operators work correctly

Windows are relatively recent: Frames from the 1990s or later are typically compatible with current IGU sizes

Only glass has failed: No structural issues, water damage, or air infiltration around frames

Cost Comparison

| Approach | Typical Cost | Performance Result |
|----------|--------------|-------------------|
| Defogging | $75-150 | Reduced (cosmetic only) |
| Glass-only replacement | $200-400 | Like-new or better |
| Full window replacement | $400-800 | Current technology |

Advantages

According to FGIA:

• 40-60% less expensive than full replacement
• Faster installation
• No frame/trim rework needed
• Can upgrade to better glass than original

Limitations

According to NFRC:

• Frame efficiency unchanged
• Limited by frame's glass pocket dimensions
• May not be possible with older or custom windows
• Some frames not designed for field replacement

Getting Better Glass Than Original

According to GANA, glass-only replacement can actually upgrade your windows:

• New Low-E coatings are better than 15-year-old ones
• Can switch from argon to krypton fill
• Upgraded spacer systems available
• May improve U-factor even with same frame

The Bottom Line

If your frames are sound but glass has failed, glass-only replacement offers a sensible middle ground—better performance than defogging at lower cost than full replacement.

*For complete guidance, see: [Foggy Windows: Repair vs. Replace](/guides/foggy-windows-repair-vs-replace)*