1. Freeze the current evidence
Photograph the full area and a close view with scale. Record date, weather, recent water use and equipment state.
2. Mark fixed comparison points
Use the same edges, fasteners, corners or measurement points on every return visit.
3. Change one condition at a time
Separate rain, fixture use, fan operation, heating and occupancy where practical. Never create an unsafe test.
4. Record negative evidence
Conditions that do not reproduce the symptom are valuable because they weaken competing causes.
5. Stop at the right boundary
Do not open energized equipment, disturb suspected hazardous material or enter unsafe roofs and confined spaces.
Observe→Compare triggers→Repair source→Verify outcome
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