When mold grows in an attic, it’s caused by a moisture problem. Some moisture sources are obvious and have a huge impact – bathroom exhaust fans, kitchen exhaust fans, clothes dryers… they all pump moisture out of the house, and they should never be vented in to the attic.
The less then obvious moisture sources are attic bypasses; air leaks that allow relatively warm, moist air from the house to get in to the attic. To reduce the amount of moisture getting in to an attic, the attic air leaks need to be sealed off.
Q) Can a home inspector tell me if there is mould in my attic?