Mold is a fungus. The fungus most people are most familiar with are mushrooms. Unlike mushrooms with produce mushroom caps that rise out of the ground to produce spores, molds produce little hair like structures that grow up off of the mold’s food source and release spores. Molds live on and eat any dead organic matter. Unfortunately, that means that molds can live on and eat the wood that makes up a building and anything in the building that contains organic matter, like drywall which usually has a paper outer surface. If allowed to grow for an extended period of time, mold can actually damage the structure of a building.
Molds also create a health problem for building occupants. The spores molds release into the air can cause people to have an allergic reaction including congestion and sneezing, can trigger and aggravate asthma, can cause skin rashes, and can cause flu-like symptoms. In some cases, mold can cause fungal infections, hypersensitivity pneumonitis, allergic bronchopulmonary aspergillosis, or allergic fungal sinusitis.
Molds can only grow in a building if there is sufficient moisture (water). As a result, if excessive mold is growing in a home, there is likely a water problem in the building, often water leaking into the building somewhere. Mold growth is a good sign that there is a larger problem and that the building should be evaluated by a professional.