What this video covers
The clip covers an attic that went unchecked for five years.
Poor roof ventilation trapped moist air against the underside of the sheathing through every heating season. Nothing about the situation was visible from the living space below.
The takeaway
Attics fail through ventilation rather than leaks. If yours has blocked soffit vents or insulation pushed over them, that is the condition to fix before anything else.
Read the full written guide: Attic Mold Removal.