02.The cause of mould
Moisture is a vital element in the development of mould. There are several ways in which moisture can enter the home and create a mould problem.
A leaky roof, broken pipes, or water from a flood can be external causes of moisture in the house. “Mould can grow very quickly and rapidly becomes a problem in areas that have been flooded – Hurricane Katrina, the Brisbane floods and the Japanese tsunami all saw serious mould issues emerge very rapidly once the flood waters had subsided,” says Prof Carter.
Moisture can also be created within the building itself: through the overcrowding of rooms (people breathing and sweating creates moisture), air drying of clothes indoors, appliances such as stoves, washing machines and dishwashers with no exhaust systems, and poor temperature control, leading to condensation on windows and walls.
“When it’s 40 degrees outside and you set your thermostat to icebox inside, if there’s a gap in the window or you open the door, hot, moist air will enter the home and condense on interior surfaces. This also happens if it’s very cold outside, but you inconsistently heat the inside of the house,” says Cheong. “In our experience, that is the main issue that people have – it’s moisture.”
Mould also needs organic matter, such as dust, to thrive. “We have dust everywhere, and mould feeds on dust. Trying to get rid of it is difficult. It’s important we keep up our housekeeping, cleaning our homes to reduce the amount of food source in the building,” says Cheong. Dust and other organic material, such as dead skin flakes, accumulates in areas with carpeting, or in closets or other areas with poor ventilation.
Prevention is better than cure
Bathrooms are mould havens. To keep mould to a minimum, install a good exhaust fan and prevent moisture build-up on surfaces. Squeegee or towel-dry your tiles and floors immediately after showering, and make sure you clean up scum, which mould feeds on.
Cheong says that once mould takes hold on grout, getting rid of it is almost impossible. “There’s not much we can do about mould in grout and silicone. When mould grows, it develops hyphae, which are roots, which grow into the grout or silicone. You can clean the surfaces of the grout or silicone, but not deep into it. In those cases you have to replace the silicone or re-grout your bathroom.”
Building ventilation is vital in homes. Cheong says inadequate ventilation is one of the main reasons homes become vulnerable to mould growth. “When the air stops moving, you can get a build-up of humidity and moisture in those areas,” he says.
Australians need to make informed heating and cooling choices to ensure mould doesn’t develop. Several of our experts warned against the use of unflued gas heaters, which release moisture into the air, and said temperature changes indoors, as well as a reluctance to open windows to promote air flow, can lead to problems. “Australian houses used to be designed well… but the use of air conditioning and central heating and the desire for more insulation have reduced this,” says Prof Carter.
Cheong says: “Environments like Darwin or Tasmania, they have moisture issues because they face wet conditions. If you look at the architecture of Darwin in the old days, there used to be high ceilings, ceiling fans on all the time, large windows. That stopped the moisture from accumulating. But now we stick an air conditioner in, we shut our home up, we’re too busy working so don’t vacuum or clean and we don’t get the dust out of our rugs, which results in more and more buildings getting moisture in them, and of course mould is going to grow.”