1. Stop at the safety boundary
Do not drill the glazing unit or use temporary vent holes as a durable repair.
2. Capture the baseline
Take one context photo, one close view and a short note describing location, date, weather, recent water use, equipment state and occupancy.
3. Track the trigger
Temperature changes and aging seals.
4. Compare, do not assume
Supports this pathway
- The fog cannot be wiped from either side
- It changes with sun and temperature
- Only the sealed unit is affected
Weakens this pathway
- Moisture is on the room surface
- The frame leaks during rain
- A removable storm panel is involved instead
5. Repeat only safe checks
- Confirm which surface holds the moisture
- Photograph under changing light
- Check whether the frame also has separate leakage symptoms
6. Decide the next step
If the pattern is active, expanding, safety-related or requires opening inaccessible construction, stop self-help testing and prepare an evidence-based handoff. A glazing professional can assess unit replacement while preserving a serviceable frame.
7. Verify the outcome
After any action, repeat the same observation under a comparable trigger. A dry surface immediately after work is not sufficient proof when the original symptom was intermittent.
Observe→Compare triggers→Repair source→Verify outcome
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