Penicillium has several different molds in its family. These species adapt easily to the growth conditions inside a building and develop well on wet building materials.

Penicillium is most commonly found in soil, indoor air, decaying plants and compost, as well as wood, dry food, spices, cereals, fresh fruit and vegetables.

They are also found growing on construction materials in water-damaged environments, such as gypsum board, insulation materials, fiberglass liners and carpets.

All of these molds can grow in cooler environments, up to 5 degrees celcius.