attic condensation

https://kilo-wiki.win/index.php/How_to_Tell_Attic_Condensation_from_a_Roof_Leak_Before_Calling_for_Repairs

Attic condensation forms when warm, moist air from the house rises into the cold attic space, then hits the underside of the roof deck and cools, releasing its moisture. This can lead to water droplets forming on the roof sheathing, especially in winter. If left unchecked, it causes wood rot, mold, and ruined insulation, so proper ventilation and sealing air leaks are essential.