Mould Growth

When excessive moisture or water accumulates indoors, mould growth will often occur, particularly if the moisture problem remains undiscovered or unaddressed. There is no practical way to eliminate all mould and mould spores in the indoor environment; the way to control indoor mould growth is to control moisture.

Mould growth on the drywall ceiling in a corner Mould growth on a drywall partition in a basement

Mould needs four things to Grow Indoors

Spores - these are always present in our environment whether indoors or outdoors. There is no such thing as a mould free environment.

Nutrients (food) - in the indoor environment these are normally the cellulose materials (paper, wood, cardboard, fabrics, dust, etc.)

Moisture - this is required to begin the decaying process of the cellulose material by the mould.

Time - growth typically begins between 24 hours and 10 days from the provision of the growing conditions.

Control Moisture

There is no means of controlling the presence of spores, the presence of nutrients or the passage of time. The only thing that can be controlled is the moisture.

Mould growth under a basement service stair from prolonged leakage from the laundry room located directly above. Mould growth due to condensation forming at the thermal bridge at wall stud locations due to elevated humidity levels

Sources of Moisture

Direct Water Penetration: e.g. Leaks in the basement, roof, around doors and windows, ice damming in winter, penetrations in the building envelope, wet building materials.

Flooding: e.g. Plumbing leaks, accidental spillage, storm flooding, sewer backup.

Condensation and humidity: e.g. drying of the structure, construction heaters, lifestyle, lack of insulation, lack of ventilation, design issues.

Why is Mould such a big problem

There are a number of reasons why mould contamination is becoming more common in our society. One of the main reasons is that more research has been done into the Health Effects of moulds and more links have been found to such things as Asthma. This has also prompted more media coverage and more people are aware of the dangers. Another reason is that there has also been a change in the way that buildings are constructed. Generally buildings are much more air tight today than they have ever been, insulation levels have been increased, but there is often little attention paid to the mechanical system and in particular to the supply of fresh air. This means that it is difficult to control humidity levels and condensation and this small amount of moisture is often all that it takes for mould growth to start. Once the growth begins, extreme colonization can occur very quickly if the conditions are optimized. One other reason is that general quality of construction in a booming economy often produces an inferior product because time and profit are paramount. Well designed, well built and well maintained buildings rarely have mould contamination problems.

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