First, work out exactly where the moisture is forming — that determines whether any repair is needed at all.
Where is the moisture?
- On the room side — ordinary condensation. Not a window defect, but a ventilation and humidity issue in the room.
- On the outside — dew on energy-efficient glass on cool mornings. This is normal and even indicates good insulation.
- Between the panes — the unit has lost its seal. This can only be fixed by replacing the unit.
Why a unit loses its seal
A glass unit is a sealed chamber filled with dried air or argon. The spacer’s desiccant saturates over the years, the sealant ages, and micro-cracks let humid air in. A unit’s average life is 15–25 years; less with poor installation or thermal stress.
A fogged unit is not just cosmetic: moisture between the panes means the argon is gone and the unit’s insulation has degraded significantly.
What the technician does
The technician measures the old unit, orders a new one with the same or better glass (e.g. energy-efficient Low-E) and replaces it without touching the frame or sash. Replacement takes 30–60 minutes per window. The price — from €80 depending on size and glass type.
Can a unit be “dried out”?
Offers to drill the unit and dry it are a short-lived cosmetic fix: the seal is not restored, the argon is gone, and the fog soon returns. The only lasting solution is unit replacement.
Conclusion: A fogged unit does not mean a new window — the frame and hardware stay, only the glazing changes. Replacement from €80 restores both the view and the insulation.