How Fast Does Mould Grow On Building Materials?

Under experimental conditions moulds are found to cover artificially inoculated building materials in 4-10 days. For example, fast growing strains of Stachybotrys chartarum produce visible mould growth on new water-damaged gypsum boards in 5 days. Slow growing strains of Stachybotrys take 14 days to completely cover the test materials. These observations suggest that visible mould growth could appear within 1-3 weeks after water damage. Under natural conditions mould growth is influenced by a … [Read more...]

Water Damaged Homes: The Primary, Secondary and Tertiary Colonizers.

If a water problem in a building is not repaired and the water dried out within 48 hours, growth of mould and other microorganisms would naturally occur. The types of moulds predominant at anyone time would be determined by the level of moisture in the building material. This level of moisture is usually referred to as the water activity and it determines the order in which different categories of moulds appear. The first group of moulds to appear (at water activities less than 0.85) is referred … [Read more...]

What Are Some Of The Mycotoxins Producing Indoor Moulds?

Growth of mould on building materials is determined by the water activity (aw) among other factors. The aw is a measure of the moistness of the material. Some moulds are capable of growing over a wide range of aw but there is always an optimal range. While these moulds grow, they reach a stage when they produce mycotoxins depending on the growth conditions. Some of the indoor moulds that produce mycotoxins are discussed below. Stachybotrys chartarum Stachybotrys chartarum is cosmopolitan and … [Read more...]

Which Moulds Grow in Buildings And Why Do They Grow?

The level of moisture (usually referred to as water activity) in building material determines not only whether mould will grow or not but also the types that colonize the material. Damp materials with a water activity value equal to or greater than 0.90 are usually colonized by strains of Aspergillus fumigatus, Trichoderma spp., Exophiala spp., Stachybotrys spp., Phialophora spp., Fusarium spp., Ulocladium spp., and yeasts such as Rhodotorula spp. Materials with a water activity value ranging … [Read more...]