Attic mold is a winter issue – When an attic stays warm, or has visible icing, no snow is showing on the roof and your neighbors have snow on their roof; This isn’t necessarily an insulation issue.  It could be the result of  a venting and humidity issue. Check to see if your home’s furnace humidifier is set too high.  A rule of thumb, if you’re noticing moisture on the inside of the windows throughout the home (not just the kitchen or bathroom) then you are adding too much moisture into the air.  Each person in a household produces 75 gallons of water per day thru breathing, perspiring, cooking and bathing. Pets also add to the humidity of the home, especially fish tanks.  All the moisture travels to the relatively cold attic and condenses on the attic roof decking.  Attics in Northern Ohio have areas that stay colder than other parts.  It’s common for the north side of the attic to have more mold damage then the rest of the attic. This happens because  the north side receives less direct sun on the exterior of the roof.   Attics with bath venting directed into the attic may have dark mold staining near the bath fan discharge.