Typical signs
- Fog, deposits or droplets that cannot be wiped from either side.
Where it is often found
- Double- or triple-glazed windows and glazed doors.
What it can mean
- Perimeter seal failure, ageing, heat or frame stress.
What to check next
- Confirm condensation is between panes.
- Check frame drainage and separate signs of water intrusion.
Reasonable immediate actions
- Document for warranty and temporarily improve humidity control.
When to stop and call a professional
- Rotten frame, cracked glass, water intrusion or high-elevation replacement.
Prevention
- Clear frame drainage, maintained seals and stress-free installation.