Can you replace only the glass unit without the frame

Can you replace only the glass unit without the frame?

Summary:

• In many cases you can replace only the sealed glass unit if the frame is sound.
• Typical reasons: condensation inside the unit, cracked glass, or wanting better insulation.
• A professional must check beads, seals, and sash geometry before work.
• Replacing only the glass unit is usually quicker and cheaper than full frame replacement.
• There are limits on unit thickness and fitting tolerances.
• After replacement, check hardware adjustment and airtightness.

Overview

Many homeowners ask whether it's possible to keep the existing frame and change only the insulated glass unit (IGU). The answer is: often yes — but only when the existing frame and sash are in good condition and compatible with the new unit.

When replacing only the glass unit makes sense

• The IGU has lost its hermetic seal and shows fogging or moisture between panes.
• One pane is cracked or broken while the frame remains square and intact.
• You want to upgrade to low‑E glass, thicker units, or inert gas fill for better thermal or acoustic performance.

If the frame is warped, rotted (in timber), corroded (in aluminium) or the PVC profile is deformed, a full replacement of the sash or entire frame is usually recommended.

Technical checks a fitter will perform

• Beads and glazing stops: they must be removable and able to hold a new unit securely.
• Depth and width of the glazing rebate: the frame must accommodate the new IGU thickness (common ranges 24–44 mm).
• Seals and gaskets: old seals may need replacement to restore airtightness.
• Sash geometry and hardware: a deformed sash will prevent proper sealing even with a new unit.

Typical replacement workflow

1. Inspection and precise measurements.
2. Careful removal of glazing beads and extraction of the old IGU.
3. Cleaning and preparation of the rebate, replacement of damaged beads or blocks.
4. Installation of the new IGU, setting blocks and gaskets, sealing.
5. Adjustment of hardware and final airtightness check.
6. Clean-up and handover.

Pros and cons

• Pros:
  • Lower cost compared to full frame replacement.
  • Faster: often completed in hours or a single day for one window.
  • Possible performance upgrade (thermal/sound) without changing frames.
• Cons:
  • Not all frames accept thicker or specialty IGUs.
  • Old frames with poor condition will limit the benefit.
  • Some warranties may not cover partial repairs if work is done by third parties.

Timing, warranty and cost

Work usually takes from a few hours up to 1–2 days depending on quantity and complexity. Manufacturers/installers provide warranty on the IGU and seal, but check whether accompanying parts (beads, gaskets) are included.

When you should replace the entire window

• Frame is deformed, soft, or damaged beyond repair.
• Hardware is obsolete or irreparable.
• You need a different opening type or improved ventilation features.

FAQ

Q: Can I install any IGU in the old frame?
A: No. The IGU must match the rebate dimensions and allow for gaskets and beads. Oversized or undersized units will cause problems.

Q: How do I recognize a failed IGU?
A: Persistent fogging/condensation between panes and reduced insulation performance are common signs.

Q: Should seals and beads be replaced too?
A: It is recommended: new seals restore airtightness and prolong the lifespan of the new IGU.

Q: Is DIY replacement safe?
A: DIY risks include damaging beads or frame, incorrect setting of support blocks, and poor sealing. Professional installation is advisable.

Q: How much will it cost?
A: Cost varies by region, glass type and complexity. A site visit and measurement are required for an accurate quote.

Recommendations

• Book a professional inspection before ordering an IGU.
• Replace seals and check hardware when installing a new unit.
• Keep documentation and warranties from the installer.

If you want, we can arrange a site visit for measurement and a no‑obligation quote — tell us your city and window type.