What do moulds need for growth?
Two things, and two things only: food and moisture. As just discussed, there are moulds that specialize in eating just about every possible type of organic material. The most commonly found moulds indoors are Aspergillus, Alternaria, Cladosporium, and Penicillium. When provided with suitable food (e.g., a ceiling tile or some drywall) and moisture (in the form of very high humidity, condensation, or water from a leaking pipe), these genera of fungi will gladly setup housekeeping and begin to grow.
