MOULD ASSESSMENT | MOULD REMEDIATION | CONSULTING 

According to the Canadian Construction Association Mould Guidelines for the Canadian Construction Industry,  "The term “mould” applies to a large group of microorganisms, which, together with mushrooms and yeast, form the Fungi Kingdom of living matter. Over 100,000 individual species of mould have been identifi ed and biologists estimate there may be over 1.5 million species worldwide. Mould organisms grow by degrading nutrients from organic substrates such as wood and wood products, fabrics, foodstuffs, plants and plant debris, and soil. They play an essential role in the natural world. Mould is one of the principal decomposers of organic matter and through the decomposition process, essential nutrients are made available to other organisms. Mildew is a common term applied to a variety of moulds that grow on plants or household items under damp conditions.

The term "mould" describes more than a million species of microscopic fungi that grow on wet or damp organic matter; for example, paper, fabric, wood, cellulose-containing materials, insulation or ceiling tiles. Several hundred of these organisms may be present in indoor environments. The growth requirements for most indoor moulds are relatively simple: oxygen (usually), suitable temperature range, a supply of nutrients and excess moisture. Moisture is the factor that is most controllable and should be the focus of mould prevention and initial remedial efforts. Moulds typically grow in buildings affected by water damage and are a potential cause of many health problems including asthma, sinusitis, and infections. Moulds may also play a major role in cases of sick building syndrome and related illnesses. Allergic reactions can be caused by moulds.

Most moulds reproduce by forming large numbers of spores. Mould spores are always present outdoors and in buildings, and are distributed by wind, insects, fl oods, animal and human activity. All buildings have a background concentration of settled spores. However, these spores do not pose a hazard until the three essential conditions for mould growth are present, namely, a suitable temperature, appropriate substrate and adequate moisture. Some species of mould grow even in extreme temperatures, for example, just above the freezing point of water and up to temperatures of at least 40oC. Moulds will colonize on a wide variety of construction materials and building contents, the most common being drywall, wood and wood products, ceiling tiles, wallpaper, and carpets. Exposed soil within a building (e.g., a dirt crawlspace) is another area of potential mould growth. While some inorganic materials such as fibreglass insulation or plaster and other masonry products may not themselves support mould growth they may contain dirt or have surface coatings that support growth. The presence of moisture may be due to either flooding(e.g., a rain storm or broken pipe), or conditions of relative humidity and condensation which can result in trapped moisture in a wall cavity, cold sections of air conditioning equipment and ductwork, or cool surfaces in unventilated, unheated areas. By their very nature, construction sites are prone to wetness or uncontrolled humidity.

Under the appropriate conditions, mould grows rapidly. The spores develop a root-like structure within hours of wetting and many common mould species produce visible colonization and masses of spores within 3-5 days. Mould growth on building fi nishes and contents normally appears as a pattern of black, green or grey spotty circular growth or as masses of fi ne, white, fl uffy growth. Generally, once the conditions of adequate moisture have been established, many types of mould may colonize a surface. A musty, earthy odour, which results from the release of metabolic by-products, is often present as the mould grows. Mould growth may produce billions of spores per square metre of visible growth which, when airborne, may pose a potential health risk.

The wet conditions in buildings that promote mould growth can also foster the growth of other microorganisms, some of which may also pose a health risk. For example, actinomycetes are a class of bacteria that form long fi laments of powdery growth of various colours on soil and other organic materials and may be mistaken for mould growth. Gramnegative bacteria are a class of bacteria that may also colonize building materials. Bacterial growth often produces a sour or rank odour. Generally, the measures outlined in these guidelines to prevent and remediate mould growth are also suitable for preventing and controlling environmental bacterial growth."

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