Leak detection in Hook: does a wall mark follow rain or plumbing use?

Fix the wall location

Photograph the room, exterior elevation and spaces above. Mark the stain boundary and note softness, odour and height.

Do not drill the wall or climb outside in wet conditions. Water may travel within cavities.

Create the weather sequence

Use official rainfall and wind information, recording delays before change. Take matched images after dry and wet periods.

Do not hose the wall or gutter to force ingress. Artificial direction and volume can mislead.

Create the plumbing sequence

Record shower, basin, toilet, heating and appliance use near the wall. Include events with no visible change.

Stop normal use if the mark repeatedly worsens. Do not run multiple fittings at once.

Present both routes

Give both timelines for leak detection in Hook. Plumbing and building-envelope assessment may need coordination.

Ask each contractor to state what they inspected and what remains possible. One negative check does not clear the other route.

Monitor the repaired condition

Photograph the repair and original mark before decoration. Follow drying advice.

Check through the relevant normal event and record which one occurred. Residual staining differs from new darkening or wetness and should not be confused in the handover.

Coordinate access on both elevations

Note shared alleys, locked gardens, neighbouring walls and high-level details that require safe equipment. Do not assume exterior inspection can be completed from inside a window.

If separate trades attend, give both the same plan and event record. Request written limits from each. A joined chronology reduces the chance that rainwater and plumbing explanations are passed back and forth without either being properly tested.

Use a matrix rather than a guess

Create four simple rows: rain with plumbing use, rain without it, dry weather with plumbing use, and dry weather without it. Add only observations that genuinely occurred; do not manufacture missing combinations.

This matrix can show which event consistently precedes change and which remains untested. Give it to the investigator with photographs. It clarifies uncertainty without pretending that correlation alone proves the physical route.

After repair, repeat only the naturally occurring row relevant to that route. Preserve the other untested possibilities in the report instead of marking the complete wall system as cleared.