What is mould?
Mould is a type of fungi. Approximately 69,000 species of fungi have been documented in scientific literature and estimates for the total number exceed 1.5 million. Fungi are a necessary part of nature’s recycling system. They break down natural organic matter such as, leaves, wood and plants. Hence when conditions are favorable for growth, i.e. appropriate moisture levels are present, mould may grow on building products such as lumber, wood paneling, insulations, adhesives, and gypsum board, all of which contain or are organic material. Moulds will also grow on dust and coatings, both which may be present on non-organic materials, examples are glass or steel.
Mould spores exist in our normal environment and the potential for mould growth exists when and where the conditions are ripe for its growth. Gypsum board is not the cause of mould growth. Stored, handled, installed and maintained properly (within Gypsum Association recommended guidelines), gypsum board will perform for its intended application.
GYPSUM BOARD MUST ALWAYS BE KEPT DRY to prevent the growth of mould. Note: If issues relating to mould arise in the field that you feel are beyond the scope of your knowledge or authority to act upon, please consult with your CertainTeed representative.
How does mould spread?
Airborn mould spores land on a food source and when the appropriate conditions are present, the spore produces root like filaments that spread along the surface. As the mould grows it can then release new spores into the air, like seeds, to propagate. It is important to note that mould spores exist naturally and are everywhere in the indoor and outdoor environment. Once the appropriate conditions for mould growth are removed, then moulds will go dormant until favorable conditions are re-introduced and they will renew their growth. There is no practical way to eliminate all mould and mould spores in the indoor environment.
What are the appropriate conditions for mould to grow?
Moulds require moisture, oxygen, appropriate temperature conditions, a food source and the presence of spores in order to grow. Most moulds prefer a temperature range that humans find comfortable. Since we cannot control the presence of oxygen, spores, nor a food source, moisture is the only condition we can control
GA-231-03: ASSESSING WATER DAMAGE TO GYPSUM BOARD
Where does mould grow in buildings?
Anywhere where moisture and a food source exist are potential areas for mould growth. Examples of sources of moisture that may contact building materials are as follows:
• Freshly poured concrete
• Plumbing leaks
• Roof/building envelope leaks
• Problem windows or detailing
• Poor drainage planes or designs
How do I minimize the potential for mould growth during construction?
Job site handling and storage of building materials is essential to reducing the potential for mould growth. Store building materials in areas that are sheltered from moisture (rain and snow) and protect them from other moisture sources, such as fresh concrete and standing water. During application and finishing of gypsum board, the site conditions should be maintained as per ASTM C 840 and GA-216 requirements. In addition, it may be necessary to consider dehumidification of the site to reduce moisture load in the building.
GA-231-03: ASSESSING WATER DAMAGE TO GYPSUM BOARD
GA-238-03: GUIDELINES FOR PREVENTION OF MOULD GROWTH ON GYPSUM BOARD
How long does it take for mould to grow?
Moulds growth can occur within 48-72 hours from the initial wetting period. If the presence of moisture is noted, then drying should take place immediately in order to minimize the potential for mould growth.
What are the possible health effects of mould exposure?
We are exposed to mould and mould spores throughout our day in our natural environment. This does not mean that if you find mould that you should not take basic precautions such as gloves and a mask, but the concern is greater for people with compromised or suppressed immune systems where exposure can lead to problems with allergic reactions or infection. The type and concentration of mould and the method of exposure will have an effect.
How should mould growth be handled?
If the mould cannot be cleaned (if growth is on gypsum board then removal and replacement is recommended), then the affected area should be removed and replaced. Also, the source of moisture must be identified and corrected or the potential for reoccurrence of mould growth is very high. Precautions should be taken during the removal and cleaning of the effected area to minimize the exposure to the mould and the spread of spores (HEPA filter respirator, gloves and HEPA filter vacuum). An appropriate resource should be consulted to ensure that proper steps are taken, CertainTeed personnel are not qualified to consult in this area |
