Roof drainage observations: trace where water is meant to go

Make a simple drainage map

From safe ground-level and interior positions, note roof sections, valleys, visible gutters or drains, downspouts and where discharge appears to go. Add overflow, ponding or staining only as observations with dates and conditions.

Do not climb onto the roof, open drains or assume a visible low point explains an interior leak. The map is a briefing for a qualified inspection, not a hydraulic calculation or diagnosis.

Record the conditions around each observation

Note whether the observation occurred during rain, after a storm, during snowmelt or in dry weather. Photograph wide context before closer safe views and retain the original date.

Department of Energy guidance for roof-based rainwater collection recommends keeping roof and gutter components clear of excessive debris and checking that water flows and drains as intended. Ask the inspector to distinguish routine debris, damaged components and system-design questions.

Ask what was actually inspected

Request a written list of accessible drainage components and areas not reached. Ask whether the provider observed attachments, seams, transitions, discharge locations and adjacent roof or wall conditions relevant to its recommendation.

If cleaning, repair or redesign is proposed, ask what condition each item addresses, what work is included and which trade is responsible for below-grade, structural or site-drainage questions outside the roofing scope.

Define the follow-up evidence

For completed work, retain before-and-after photos, the exact component locations, the accepted scope and any maintenance instructions. Ask what safe observation would trigger a return visit.

Continue the map as part of the roof maintenance record. If water appears in a new location or the pattern changes, record the difference and request reassessment instead of assuming the earlier cause applies.

Related guides

• Build a roof maintenance record that stays useful
• What to ask for in a roof inspection report
• Roof leak checklist: what to record before the inspection