1. Stop at the safety boundary
Do not smear sealant across every visible joint; that can trap water and obscure the failed layer.
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
Rain, wind exposure and chimney orientation.
4. Compare, do not assume
Supports this pathway
- Staining aligns with the chimney side or upslope corner
- Wind direction changes severity
- Attic evidence follows framing away from the chimney
Weakens this pathway
- The symptom follows fireplace use rather than rain
- The chimney area stays dry through repeated storms
- A plumbing line directly above reproduces the mark
5. Repeat only safe checks
- Map which chimney face received the weather
- Photograph flashing from the ground with zoom rather than climbing
- Compare attic marks before and after one documented storm
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 roofer or chimney specialist should inspect inaccessible flashing, masonry movement and cap details.
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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