Questions about replacing glass units

Questions about replacing glass units

Replacing a glass unit (insulating glass unit, IGU) is a common task when renovating windows or improving energy efficiency. A correctly chosen and professionally installed glass unit restores warmth, improves sound insulation and extends the life of a PVC window. This guide explains when replacement is needed, what types of units exist, and practical advice for ordering and installation.

When do you really need to replace an IGU?

• Moisture or condensation appears between panes — a clear sign of lost hermetic seal.
• Cracks or chips in the glass reduce strength and insulation.
• Noticeable drafts or worsening sound insulation with closed sashes.
• Old spacer bars causing thermal bridging — consider a warm spacer.
• Aesthetic reasons: faded glass or different light transmission needs.

Types of glass units and their purpose

• Single-chamber (double-glazed) units — budget choice for moderate climates.
• Double-chamber (triple-glazed) units — better thermal and acoustic performance for cold regions.
• Low-emissivity (Low-E) units — reduce heat loss with special coatings and gas fills (argon, krypton).
• Acoustic units — different glass thicknesses and interlayers to reduce noise.
• Safety/impact-resistant units — for enhanced security.

How to diagnose the condition

• Inspect seals and edges for moisture or frost between panes.
• Check for cold spots around the perimeter in windy weather — use touch or a thermal camera.
• Look for fogging, bubbles or milky stains between glasses — indicates seal failure.
• Verify hardware operation — often drafts are due to misadjusted fittings, not the IGU.

Replacement process (step-by-step)

1. Remove sash from hinges if necessary.
2. Remove decorative trims and glazing beads.
3. Carefully remove old glass unit.
4. Prepare the frame: clean the groove, inspect and replace seals if needed.
5. Install new IGU with shims and level it correctly.
6. Refit glazing beads, adjust hardware and test the seal.

Tip: To maintain warranty and quality, have certified installers perform the work.

Cost and timing

• Price depends on size, type of glass, Low-E coatings, gas fill, and complexity of removal.
• Replacing a standard single-chamber unit usually takes 1–3 hours per window; for double-chamber units allow up to 3–5 hours.
• Consider charges for measuring visit, custom manufacturing and installation.

Selection tips

• In cold climates choose double-chamber IGUs with Low-E coating and argon fill.
• For noise reduction use different glass thickness and acoustic spacers.
• Warm spacer bars reduce thermal bridges along the perimeter.
• Check certificates and warranty for both glass units and installation services.

Frequently Asked Questions

Do I have to replace the whole frame if the IGU is damaged?

Not necessarily. Often replacing only the IGU is sufficient if the profile and hardware are in good condition. Frame replacement is required if the profile is deformed, severely damaged, or you want a different opening type.

Can I replace the IGU myself?

Technically possible, but without experience you risk damaging glazing beads, seals or the profile. Incorrect installation leads to heat loss and may void warranties. We recommend professional installers.

How long does a new IGU last?

With proper installation and maintenance, 15–30 years depending on materials and conditions.

Is it better to replace the IGU or add an internal secondary glazing?

Generally, modern IGU replacement is more efficient and long-term. Secondary glazing can be a temporary or niche solution but is often less convenient.

Do I need permission from the building management?

If you replace IGUs inside your apartment, usually no special permits are needed, but check building rules. External or façade work may require approvals.

Conclusion

Replacing an IGU is an effective way to increase comfort and reduce heating costs. Proper diagnosis, selecting the right type of unit and professional installation are critical. When in doubt, order a site inspection and specialist consultation to choose the optimal solution for your windows.