Condensation between the panes of a double-glazed unit signals a seal failure that requires attention. This guide helps you identify the problem and choose between repair and replacement.
Types of Window Condensation
1. Interior Condensation (on the room-side pane)
Cause: Excessive humidity in indoor air Severity: Low - ventilation problem, not a window defect
2. Condensation Between the Panes
Cause: Seal failure in the double-glazed unit Severity: High - the double glazing has failed
3. Exterior Condensation (on the outer pane)
Cause: Excellent thermal insulation of the glazing Severity: None - this is a sign of good thermal performance
Repair or Replace?
Option 1: Replace the Glazing Unit Only
When to choose this:
- The frame is in good condition
- The windows are less than 15 years old
- Budget is limited
Cost:
- Standard double glazing: €150-300/m²
- Labour: €80-150 per window
- Total for a standard window: €300-650
Option 2: Full Window Replacement
When to choose this:
- Windows are more than 20 years old
- Frame is deteriorated
- Wish to improve insulation performance
Cost:
| Window Type | Price including installation |
|---|---|
| PVC double glazing | €500-900 |
| Timber double glazing | €700-1,200 |
| Aluminium double glazing | €800-1,400 |
| PVC triple glazing | €700-1,100 |
Pros and Cons
Glazing-Only Replacement
Pros:
- Lower cost (30-50% cheaper)
- Quick intervention
- Keeps the existing frame
Cons:
- Performance limited by the old frame
- Potentially shorter lifespan
Full Window Replacement
Pros:
- Optimal performance
- Full manufacturer guarantee (10 years)
- Adds to property value
- Significant energy savings
Cons:
- Higher cost
- Manufacturing lead time (2-6 weeks)
Financial Grants in Luxembourg
Window replacement may be eligible for Klimabonus grants:
Conditions:
- Uw coefficient ≤ 1.3 W/m²K (high-performance double glazing)
- Uw coefficient ≤ 1.0 W/m²K (triple glazing)
- Installation by a certified professional
Find a Joiner on tack.lu
More than 60 professional joiners and window fitters are listed on tack.lu in Luxembourg.
FAQ
How long does double glazing last?
Good-quality double glazing lasts 15-25 years. The first signs of seal failure often appear after 15-20 years.
Can condensation between panes clear by itself?
No. Once the seal is compromised, the problem only worsens over time.
Is triple glazing always better?
Triple glazing offers better thermal insulation but is heavier and more expensive. It is mainly recommended for north-facing windows or passive houses.
