01
Record the weather conditions
Note wind direction, rainfall intensity, duration and when interior moisture begins. Photograph the stain and mark its position relative to roof features.
02
Inspect upslope transitions
Water may travel along decking or framing before appearing indoors. Examine valleys, sidewalls, chimneys, penetrations and built-in gutters upslope—not only the slate directly above the stain.
03
Use controlled testing carefully
Qualified professionals may isolate roof sections with a controlled water test. Work from low to high and allow time between zones so results are not confused.