Choose the closest starting point.
You do not need the technical name. Pick the closest observation and the engine will ask for the evidence that separates competing explanations.
SeeBrown or yellow ceiling stain→SmellMusty or damp smell→SeeCondensation on or inside windows→SeeBlack spots around a window→SeeWhite powder on a basement wall→SeeFrost or ice inside the attic→FeelCold floor near an exterior wall→HearGurgling drain or toilet→HearClicking or ticking pipes→HearBuzzing, hot or discolored outlet→SeeDiagonal crack above a door or window→SeeWater or staining around a window→