Why is there mold on the cathedral ceiling?
I have a customer on the eastern shore of MD. They spend the winter away from here and the house is closed up. 3-4 years ago they had a remodel done which included batt insulating and drywalling a cathedral ceiling and a new roof. As they entered the home this season they found black mold on the cathedral ceiling.
They believe that when the work was done 3-4 years ago that a ridge vent was installed but no soffit vents and no baffles between the ratfters and with the particularly bad winter we had that ice dams formed and somehow moisture got in the bays and trapped and caused mold and ruined insulation. This mold is at the flattened section near the peak of this ceiling.
After further discusssion I learned that their sump pump had failed also and that the area of the crawl space below the cathedral ceiling is without a vapor barrier. I believe that the failed sump punp and lack of vapor barrier is a more likely cause of this mold.