Moulds are organisms that are found indoors and outdoors. They are part of the natural environment and play an important role in our ecological system by breaking down and digesting organic material. Moulds are neither plants nor animals. They are Fungi.
Fungi do not make their own food the way that green plants do. Fungi get nourishment from other living organisms. The main role of fungi in the ecosystem is to break down dead materials, such as fallen leaves, trees, insects and animals carcasses. The same enzymes that assist fungi in breaking down dead materials are what help fungi to damage wooden components in a building. Molds can damage food, stored goods, and building materials of houses.
What mould needs to grow?
Most of the mould found indoors comes from the outdoors because mould spores can easily float on gentle air currents. If the spores land on suitable organic material inside a building, mould can begin to grow. But mould needs two things in order to grow and survive: moisture and food.
Moisture
Mould does not need a lot of moisture to grow. A little condensation in a bathroom or around a window sill, for example, can be enough. Common sites for indoor mould growth include bathroom tile and grout, basement walls, and areas around windows and sinks. Common sources of water or moisture include roof leaks, condensation due to high humidity or cold spots in a building, slow leaks at plumbing fixtures, humidification systems, sprinkler systems, and floods. Moisture is the most important factor influencing mould growth indoors. Controlling indoor moisture helps limit mould growth. Moisture control is the key to mould control.
Food
Besides moisture, mold needs nutrients, or food, to grow. Mould can grow on virtually any organic substance. Buildings are full of organic materials that mold can use as food, including paper, cloth, wood, plant material, and even soil. Moulds secrete digestive enzymes that decompose the substrate, making nutrients available. Some moulds can even digest synthetic materials such as adhesives, pastes and paints.
Mould requires moisture to survive, so protecting lumber and wood structures from moisture will help prevent mould growth. Mould growth can be limited if the MC of wood can be kept below 20%. An MC below 17% means that virtually no microbial growth will occur on even the most susceptible materials. Southern pine dimensional lumber is typically kiln-dried to a maximum 19% MC or less. The moisture content is indicated on the grade stamp. Moisture content is related directly to particular substrates or materials.
Remediation
Significant mould growth may require professional mould remediation and removal of affected building materials. A conservative strategy is to discard any building materials saturated by the water intrusion or having visible mould growth. New technology also allows some mould remediation companies to fill a room with a dry fog that kills the mould and stops its growth. This fog uses a chemical that is EPA approved and does not harm or damage the physical well being of persons or animals. Recently, some companies have begun using dry ice freeze blasting to remove mould from suitable surfaces, such as wood and cement. Damp wipe is the removal of mold from non-porous surfaces by wiping or scrubbing with water and a detergent. Care must be exercised to make sure the material is allowed to quickly dry to discourage any further mold growth. With surfaces such as metal, glass, hardwood, plastics, and concrete, mould should be scraped off as much as possible. Then, scrub the surface with a moldicide or fungicide cleaner.
