Start with what it resembles.
Choose the closest visual fingerprint. Then add location, timing and weather in the Clue Engine. Resemblance alone never confirms a cause.
Droplets on room-side glass
Accessible droplets are surface condensation, not sealed-unit fog.
Match this pattern →Fog trapped between panes
Inaccessible haze strongly supports a failed insulated-glass seal.
Match this pattern →Wet window head after storm
Water at the top of an opening after wind-driven rain points to flashing.
Match this pattern →