1. Stop at the safety boundary
Do not enter a wet or icy roof valley.
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
Heavy rain, leaf fall, snowmelt or freeze-thaw cycles.
4. Compare, do not assume
Supports this pathway
- Only intense storms reproduce the mark
- Debris accumulates in the valley
- The interior path follows rafters downslope
Weakens this pathway
- Light rain causes the same response
- The valley remains clean and drains freely
- A nearby plumbing event is a stronger trigger
5. Repeat only safe checks
- Observe drainage from the ground during rain
- Record storm intensity and delay
- Inspect accessible attic framing for a directional track
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 should inspect the valley covering, underlayment and adjacent flashing.
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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