Growth in Buildings
Mould (mold) and moisture damage to the building is caused by a number of factors:
- Moisture and condensation in the HVAC System.
- Leaks in the building envelope from the foundation up to the roof.
- Leaks caused by faulty plumbing or poor workmanship.
- Moisture existing in the building materials before construction and sealed into the envelope.
- Moisture caused by occupant activities such as showering or bathing.
- Moisture caused by combustion sources particularly open flame cooking and heating appliances such as stoves and water heaters.
- Poor site drainage.
Principles of Mould Assessment
Based on this protocol, Sterling IAQ Consultants Ltd. conducts inspections of HVAC systems and buildings for signs of moisture and/or visible mould growth. Sometimes baseboards and carpet are pulled back and other times a boroscope is used to inspect wall cavities or inside ductwork.
Based on the results of our visual inspections, there may be a need for sampling. There are three basic sampling methods used to assess mould contamination in buildings:
- Bulk sampling
- Surface sampling
- Air sampling
Bulk sampling involves aseptically cutting a sample of material such as wallboard, insulation, settled dust, or carpet; and determining contamination of viable organisms. This method produces qualitative rather then quantitative results by detecting the presence of a mould on or in the sample.
Surface sampling involves aseptically collecting a sample from the surface of a material such as shelves, walls or pillars. There are various methods used to collect the sample including: wetted swab, tape lift, contact plate, or a suction device such as a micro vacuum.
Again this method produces qualitative rather than quantitative results identifying the presence of a mould.
Air sampling is a method used to sample air in the occupied space of a room, in the building envelope or in the ventilation air provided by the HVAC system serving a building to determine biological contamination. There are two commonly used sampling methods:
- Total (viable + nonviable) spores – generally called spore trap sampling and has become the primary method for air sampling
- Viable (culturable) spores – was once the gold standard of testing but has decreased in popularity